后摩尔时代取代硅的微电子材料——碳纳米管和石墨烯     

翟译晨  翟冠杰 《南京气象学院学报》2011,(2):167-173

在硅电子材料即将发展到顶峰时,碳纳米管及石墨烯以其优良的导体和半导体性质将成为延续硅材料的主流微电子材料．详述了碳纳米管和石墨烯的结构与电学性质,从而说明其作为微电子材料的优势,列举了在微电子器件构建中已经取得的成果及构建器件的方法,并简述了相应碳纳米管和石墨烯的制备方法  相似文献   

Climate change diffusion: While the world tips, business schools lag     

Genevieve Patenaude   《Global Environmental Change》2011,21(1):259-271

The influence of business schools on business practitioners is considerable. An important proportion of corporate leaders hold a degree in business administration or an MBA, if not both. In the context of climate change, this influence matters: greenhouse gas (GHG) emissions from a selection of global 500 companies approximate that of the USA and the EU15 combined. Not only do corporations have a significant climate footprint, but the impact of climate change on the business landscape is already noticeable. Yet, meeting the managerial challenges that climate change brings requires knowledge only moderately addressed in business education and scholarship today. Climate change tends to be discussed in electives - hence reaching only a fraction of students - and tends to be treated alongside a myriad of other corporate social responsibility issues. Moreover, from 1992 to 2008, only seven articles with titles containing climate change or global warming were published in the top-30 peer-reviewed management journals (this paper, see also Goodall, 2008). In this paper, by mapping the diffusion of climate change within press media and academic peer-reviewed publications, I argue that understanding the existing lag in business scholarship engagement requires a fundamental understanding of processes that either hinder or lead to the diffusion of new ideas. To do so, I present a simple yet novel approach for the quantification of climate change or global warming (CCorGW) coverage relative to population size. My results on the diffusion of the climate change idea over time show: (a) an overall increase in proportional coverage in all databases (b) tipping points around the late 1980s and circa 2005 and (c) delays in adoption between press categories. I explicate the occurrence of these tipping points as well as the existence of delays by theoretically unifying my analyses with results from previous studies under the umbrella of the diffusion of innovation paradigm. I suggest that the following key factors have contributed in slowing the diffusion within business scholarship: (a) corporate values, beliefs and operational modes (b) social structures and incentives prevailing within academia and finally (b) academia's valued research communication channels. I conclude by elaborating key recommendations to facilitate the diffusion of this idea to business scholars and other influential audiences.  相似文献   

An International Relations perspective on the global politics of carbon dioxide capture and storage     

Heleen de Coninck  Karin Bäckstrand 《Global Environmental Change》2011,21(2):368-378

With the publication of the IPCC Special Report on Carbon dioxide Capture and Storage (CCS), CCS has emerged as a focal issue in international climate diplomacy and energy collaboration. This paper has two goals. The first goal is to map CCS activities in and among various types of intergovernmental organisations; the second goal is to apply International Relations (IR) theories to explain the growing diversity, overlap and fragmentation of international organisations dealing with CCS. Which international organisations embrace CCS, and which refrain from discussing it at all? What role do these institutions play in bringing CCS forward? Why is international collaboration on CCS so fragmented and weak? We utilise realism, liberal institutionalism and constructivism to provide three different interpretations of the complex global landscape of CCS governance in the context of the similarly complicated architecture of global climate policy. A realist account of CCS's fragmented international politics is power driven. International fossil fuel and energy organisations, dominated by major emitter states, take an active role in CCS. An interest-based approach, such as liberal institutionalism, claims that CCS is part of a “regime complex” rather than an integrated, hierarchical, comprehensive and international regime. Such a regime complex is exemplified by the plethora of international organisations with a role in CCS. Finally, constructivism moves beyond material and interest-based interpretations of the evolution of the institutionally fragmented architecture of global CCS governance. The 2005 IPCC Special Report on CCS demonstrates the pivotal role that ideas, norms and scientific knowledge have played in transforming the preferences of the international climate-change policy community.  相似文献   

Carbon input, production and turnover in the interstices of a Lake Tegel bank filtration site, Berlin, Germany     

Anja Hoffmann  Günter Gunkel 《Limnologica》2011,41(3):151-159

The sandy littoral zone of Lake Tegel (Berlin, Germany) was investigated during 2004–2006 down to sediment depths ≥26 cm to derive a scheme of seasonal carbon turnover under induced bank filtration conditions. Carbon turnover processes were quantified regarding external and internal sources of dissolved and particulate organic matter (DOM and POM), primary production, community respiration, redox potential as well as specific loads of soluble chemical compounds such as nitrogen, iron, manganese and DOC.Over the course of the year, infiltrating DOC decreased by about 13–20% within the upper 26 cm sediment of the infiltration stretch. Gradients of all observed soluble compounds that are highly cross-linked to biological activities were highest in the topmost centimetre. In this depth mass balances (output–input) were negative concerning NO₃-N (−1 mg dm⁻² d⁻¹, summer mean) and DOC (−2 mg dm⁻² d⁻¹, winter mean), respectively, while specific loads of cations such as manganese reached up to 0.2 mg dm⁻² d⁻¹ during summer. Carbon mineralization ranged between 3 and 7 mg C dm⁻² d⁻¹ and was nearly twice as high in summer as in winter. The turnover of the infiltrating DOC contributed maximally 25% in summer to 50% in winter to the entire organic carbon mineralization. Gross and net primary production differed up to a factor of >10, indicating very fast turnover reactions and the predominance of community respiration and mineralization, respectively. The POC in the upper sediment layer (10 cm) temporally varied around 1% sediment d.w.; benthic algae, organic seston input and autumnal leaf fall contributed similar percentages to the POC pool.  相似文献   

Seasonal distribution of the inorganic carbon system and net ecosystem production in the north eastern shelf of the Gulf of Cádiz (Southwest Iberian Peninsula)     

Mariana Ribas-Ribas  Abelardo Gómez-Parra Jesús M. Forja 《Continental Shelf Research》2011,31(18):1931-1942

There is scatter information of the inorganic carbon system in the coastal zones and it is important to increment our knowledge and understand the global carbon cycle. We investigated the distribution of inorganic carbon system parameters and its controls in the coastal waters of the north eastern shelf of the Gulf of Cádiz (GoC) during four cruises that took place in June 2006, November 2006, February 2007 and May 2007. The objectives of this study are: (1) to describe the spatio-temporal distribution of inorganic carbon system parameters in waters of the north eastern shelf of the GoC using four cruises, each undertaken in one of the four seasons, (2) to calculate net ecosystem production (NEP) and (3) to examine factors controlling these distributions. The distribution of inorganic carbon system parameters in the north eastern shelf of the Gulf of Cádiz showed temporal and spatial variability. River input, mixing, primary production, respiration, CO₂ air-sea exchange, and remineralization were factors that controlled such distributions. The coastal zone of the GoC is autotrophic on an annual scale at a rate of 1.0 mmol m⁻² d⁻¹. Further measurements are needed it to improve the NEP calculation and to evaluated to intra-annual variability.  相似文献   

遵义黄家湾Ni-Mo多金属矿床成矿流体特征:来自方解石流体包裹体、REE和C、O同位素证据     

冯彩霞  池国祥  胡瑞忠  刘燊  刘家军  罗泰义  齐有强 《岩石学报》2011,27(12):3763-3776

黄家湾矿床是近几年在贵州遵义地区寒武系底部黑色页岩中新发现的以Ni-Mo为主的多元素矿床,本文首次对该矿床成矿阶段方解石的流体包裹体、REE和C、O同位素组成特征进行了系统研究.研究结果显示:(1)该矿床成矿阶段方解石中含有3种类型的流体包裹体:富液相气液两相水溶液包裹体;富气相气液两相水溶液包裹体;纯液相包裹体.它们的气相分数变化较大,显示成矿过程中可能发生过沸腾作用.流体包裹体的显微测温结果显示,成矿流体的冰点温度为-11.6～-5.5℃,流体盐度变化范围为8.55％ ～ 15.57％ NaCleqv,均一温度为109.0 ～ 181.8℃,对应流体密度为0.97 ～ 1.44g·cm-3;(2)遵义黄家湾钼-镍多金属矿床中与成矿期有关的方解石的稀土总量高且变化范围宽(39.9×10-6～ 275×10-6),配分曲线为轻稀土富集((La/Yb)N=29.6 ～63.3)的右倾型,且铕正异常明显(Eu/Eu*为2.14～14.8),与现代海底热液矿床中方解石的稀土特征类似;(3)同位素测定显示成矿流体的碳氧同位素组成分别为δ13C V-PDB=-6.3‰～-5.7‰,δ18OV-SMOW=15.6‰ ～16.0‰,计算得到流体水的δ18OV-SMOW-H2O‰平均值变化于-0.97‰～ +5.16‰之间.上述综合研究表明:黄家湾Ni-Mo多金属矿床成矿流体主要为海水和地层中的建造水(盆地热卤水),同时由海水演化来的海底热液也参与了成矿过程.成矿流体中的碳可能由深源碳与海相碳酸盐岩共同提供.  相似文献   

Carbon isotope composition of graptolite periderm and whole-rock from the Aeronian (Silurian, Llandovery) in Wales and Scotland and its use in chemostratigraphy     

Andrea M. Snelling  Melanie J. Leng  Christopher C. Kendrick 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(1):82-91

Here we show the use of graptolite periderm for chemostratigraphic study. Using material from the Aeronian (Silurian) interval from Wales and Scotland as examples, we show that the carbon isotope composition of the periderm (δ¹³C_grap.) provides a signal that is locally different but not consistently so from surrounding whole-rock samples (δ¹³C_whole-rock). Graptolite periderm δ¹³C seems not influenced by astogenetic stage of development or gross rhabdosome type and differences between δ¹³C_grap. from different metamorphic grades are minimal. Taken as a whole, the Aeronian interval examined shows little overall change, but large variations are seen on the small scale, possibly reflecting very local carbon cycling. For carbon isotope stratigraphy in such rocks, therefore, large-scale bulk sampling will likely reduce inhomogeneities and give more reproducible results. Furthermore, in situations (for instance associated with sea level fluctuations) where terrestrial organic matter has been incorporated into the sediment, then graptolite carbon may more faithfully reflect bulk marine organic matter.  相似文献   

Cretaceous climate oscillations in the southern palaeolatitudes: New stable isotope evidence from India and Madagascar     

Yuri D. Zakharov  Yasunari ShigetaOlga P. Smyshlyaeva  Alexander M. PopovTatiana A. Velivetskaya  Tamara B. Afanasyeva 《Cretaceous Research》2011,32(5):623-645

Palaeotemperatures for the Cretaceous of India and Madagascar have been determined on the basis of oxygen isotopic analysis of well-preserved Albian belemnite rostra and Maastrichtian bivalve shells of from the Trichinopoly district, southern India, and Albian nautiloid and ammonoid cephalopods from the Mahajang Province, Madagascar. The Albian (possibly late Albian) palaeotemperatures for Trichinopoly district are inferred to range from 14.9 °C to 18.5 °C for the epipelagic zone, and from 14.3 °C to 15.9 °C for the mesopelagic zone, based on analyses of 65 samples; isotopic palaeotemperatures interpreted as summer and winter values for near-bottom shelf waters in this area fluctuate from 16.3 to 18.5 °C and from 14.9 to 16.1 °C, respectively. The mentioned palaeotemperatures are very similar to those calculated from isotopic composition of middle Albian belemnites of the middle latitude area of Pas-de-Calais in Northern hemisphere but significantly higher than those calculated from isotopic composition of Albian belemnites from southern Argentina and the Antarctic and middle Albian belemnites of Australia located within the warm-temperate climatic zone. Isotopic analysis of early Albian cephalopods from Madagascar shows somewhat higher palaeotemperatures for summer near-bottom shelf waters in this area (20.2-21.6 °C) in comparison with late Albian palaeotemperatures calculated from southern India fossils, but similar winter values (13.3-16.4 °C); however, the latter values are somewhat higher than those calculated from early Albian ammonoids of the tropical-subtropical climatic zone of the high latitude area of southern Alaska and the Koryak Upland. The new isotopic palaeotemperature data suggest that southern India and Madagascar were located apparently in middle latitudes (within the tropical-subtropical climatic zone) during Albian time. In contrast to the Albian fossils, isotope results of well-preserved early Maastrichtian bivalve shells from the Ariyalur Group, Trichinopoly district, are characterised by lower δ¹⁸O values (up to −5.8‰) but normal δ¹³C values, which might be a result local freshwater input into the marine environment. Our data suggest that the early Maastrichtian palaeotemperature of the southern Indian near-bottom shelf waters was probably about 21.2 °C, and that this middle latitude region continued to be a part of tropical-subtropical climatic zone, but with tendency of increasing of humidity at the end of Cretaceous time.  相似文献   

Transport of terrestrial organic matter in the Ogooué deep sea turbidite system (Gabon)     

Laurie Biscara  Thierry MulderPhilippe Martinez  François BaudinHenri Etcheber  Jean-Marie JouanneauThierry Garlan 《Marine and Petroleum Geology》2011,28(5):1061-1072

In order to define the nature and distribution of the organic matter (OM) preserved in the modern Ogooué deep sea turbidite system (Gabon), bulk geochemical techniques (Rock-Eval pyrolysis, elemental and isotopic analyses) and palynofacies were applied to three piston cores collected in the Cape Lopez Canyon and lobe and on the continental slope, north of the canyon.The hemipelagic sedimentation in the study area is characterized by high accumulations of well-preserved OM (∼2-3 wt. TOC %). Bulk geochemical and palynofacies analysis indicate both a marine and terrestrial origin of the OM. Contribution of the marine source is higher on the slope than in the canyon and lobe.OM accumulation in turbidites is strongly controlled by the combined influence of the Cape Lopez Canyon and littoral drift. In the canyon and lobe, turbidites show generally low TOC content (0.5 wt. %) and OM is oxidized. The origin of the OM is interpreted as both marine and terrestrial, with a higher contribution of continental source versus marine source. The low TOC contents are due to the large siliciclastic fraction transported by the littoral drift and diverted in the Cape Lopez Canyon during high energy processes (e.g. storms) which tend to dilute the OM in the turbidites. Transport by long-shore currents and/or turbiditic flows leads to oxidation of the OM.On the continental slope located north of the Cape Lopez Canyon, large amounts of OM are deposited in turbidites (up to 14 wt. %). The OM is predominantly derived from terrestrial land plants and has not been subjected to intense oxidation. These deposits are characterized by high hydrocarbon potential (up to 27 kg HC/t rock), indicating a good potential as gas-prone source rock. Because Cape Lopez Canyon captures a significant part of the sediment transported by the littoral drift, the siliciclastic sedimentary flux is reduced north of the canyon; OM is thus concentrated in the turbidites. Variation in TOC content within turbidite laminae can be explained by the burst and sweep deposition process affecting the boundary layer of the turbulent flow.This study confirms that gravity flows play a preponderant role in the accumulation and preservation of OM in deep water and that deep sea turbidite systems could be regarded as an environment where organic sedimentation occurs.  相似文献   

Mid-IR (8–13 μm) images of the 21 μm,carbon rich proto-planetary nebulae     

M. Meixner  J. R. Graham  C. J. Skinner  G. W. Hawkins  E. Keto  J. F. Arens  J. G. Jernigan 《Experimental Astronomy》1994,3(1-4):53-56

We present 9.7 and 11.8 m narrow band (/=10%) images of three carbon (C-) rich proto-planetary nebulae with an unusual 21 m feature: IRAS 07134+ 1005, IRAS 22272+5435, and IRAS 04296+3429. The images were taken at UKIRT using the Berkeley/IGPP/LEA mid-IR camera. All three objects have a bipolar shape adding to the existing evidence that C-rich PPNe are by nature bipolar. Furthermore, we find the same bipolar morphology in a previous study of the C-rich, young planetary nebula, IRAS 21282+5050. We believe these four objects form an evolutionary sequence which links the C-rich asymptotic giant branch (AGB) stars with the C-rich planetary nebulae (PNe). From this evolutionary sequence, we conclude that bipolarity in C-rich PNe begins on the AGB and that the dynamical ages of these PPNe are in fair agreement with theoretical ages for a 0.6 M hydrogen burning core star.  相似文献