958 resultados para crystal and ligand fields


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Graphene, with its unique electronic and structural qualities, has become an important playground for studying adsorption and assembly of various materials including organic molecules. Moreover, organic/graphene vertical structures assembled by van der Waals interaction have potential for multifunctional device applications. Here, we investigate structural and electrical properties of vertical heterostructures composed of C60 thin film on graphene. The assembled film structure of C60 on graphene is investigated using transmission electron microscopy, which reveals a uniform morphology of C60 film on graphene with a grain size as large as 500 nm. The strong epitaxial relations between C60 crystal and graphene lattice directions are found, and van der Waals ab initio calculations support the observed phenomena. Moreover, using C60-graphene heterostructures, we fabricate vertical graphene transistors incorporating n-type organic semiconducting materials with an on/off ratio above 3 × 10(3). Our work demonstrates that graphene can serve as an excellent substrate for assembly of molecules, and attained organic/graphene heterostructures have great potential for electronics applications.

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Thesis (Ph.D.)--University of Washington, 2016-08

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Thesis (Ph.D.)--University of Washington, 2016-08

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The strategy to control the noxious water hyacinth requires reliable data base on the magnitude of the weed problem. This report which presents up to date (1997) information on distribution, coverage and movement of the weed in Uganda is intended to provide this basis as suppliment to other inputs for control planning. The report is the first in a series being prepared by FIRI from results the "Water hyacinth. research project" whose major goal is to supply information needed to define and focus the scope of the control process for water hyacinth in view of the fact that the weed is to remain a permanent feature of the aquatic landscape of Uganda. Water hyacinth is firmly established in lakes Victoria, Kyoga Albert and along the River Nile, distributed in two distinct forms namely as stationary fringes the shoreline and as mobile mats and large "fields" usually found in sheltered bays.

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We revisit the visibility problem, which is traditionally known in Computer Graphics and Vision fields as the process of computing a (potentially) visible set of primitives in the computational model of a scene. We propose a hybrid solution that uses a dry structure (in the sense of data reduction), a triangulation of the type Ja
 1 , to accelerate the task of searching for visible primitives. We came up with a solution that is useful for real-time, on-line, interactive applications as 3D visualization. In such applications the main goal is to load the minimum amount of primitives from the scene during the rendering stage, as possible. For this purpose, our algorithm executes the culling by using a hybrid paradigm based on viewing-frustum, back-face culling and occlusion models. Results have shown substantial improvement over these traditional approaches if applied separately. This novel approach can be used in devices with no dedicated processors or with low processing power, as cell phones or embedded displays, or to visualize data through the Internet, as in virtual museums applications.

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Using our anholonomic frame deformation method, we show how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates and undergoing a phase of ultra-slow contraction can be constructed in massive gravity. In this paper, there are found and studied new classes of locally anisotropic and (in)homogeneous cosmological metrics with open and closed spatial geometries. The late time acceleration is present due to effective cosmological terms induced by nonlinear off-diagonal interactions and graviton mass. The off-diagonal cosmological metrics and related Stückelberg fields are constructed in explicit form up to nonholonomic frame transforms of the Friedmann–Lamaître–Robertson–Walker (FLRW) coordinates. We show that the solutions include matter, graviton mass and other effective sources modeling nonlinear gravitational and matter fields interactions in modified and/or massive gravity, with polarization of physical constants and deformations of metrics, which may explain certain dark energy and dark matter effects. There are stated and analyzed the conditions when such configurations mimic interesting solutions in general relativity and modifications and recast the general Painlevé–Gullstrand and FLRW metrics. Finally, we elaborate on a reconstruction procedure for a subclass of off-diagonal cosmological solutions which describe cyclic and ekpyrotic universes, with an emphasis on open issues and observable signatures.

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Naturally-occurring phytochemicals have received a pivotal attention in the last years, due to the increasing evidences of biological activities. Equisetum giganteum L., commonly known as “giant horsetail”, is a native plant from Central and South America, being largely used in dietary supplements as diuretic, hemostatic, antiinflammatory and anti-rheumatic agents [1,2]. The aim of the present study was to evaluate the antioxidant (scavenging effects on 2,2-diphenyl-1-picrylhydrazyl radicals- RSA, reducing power- RP, β-carotene bleaching inhibition- CBI and lipid peroxidation inhibition- LPI), anti-inflammatory (inhibition of NO production in lipopolysaccharidestimulated RAW 264.7 macrophages) and cytotoxic (in a panel of four human tumor cell lines: MCF-7- breast adenocarcinoma, NCI-H460- non-small cell lung cancer, HeLa- cervical carcinoma and HepG2- hepatocellular carcinoma; and in non-tumor porcine liver primary cells- PLP2) properties of E. giganteum, providing a phytochemical characterization of its extract (ethanol/water, 80:20, v/v), by using highperformance liquid chromatography coupled to diode array detection and electrospray ionisation mass spectrometry (HPLC-DAD–ESI/MS). E. giganteum presented fourteen phenolic compounds, two phenolic acids and twelve flavonol glycoside derivatives, mainly kaempferol derivatives, accounting to 81% of the total phenolic content, being kaempferol-O-glucoside-O-rutinoside, the most abundant molecule (7.6 mg/g extract). The extract exhibited antioxidant (EC50 values = 123, 136, 202 and 57.4 μg/mL for RSA, RP, CBI and LPI, respectively), anti-inflammatory (EC50 value = 239 μg/mL) and cytotoxic (GI50 values = 250, 258, 268 and 239 μg/mL for MCF-7, NCI-H460, HeLa and HepG2, respectively) properties, which were positively correlated with its concentration in phenolic compounds. Furthermore, up to 400 μg/mL, it did not revealed toxicity in non-tumor liver cells. Thus, this study highlights the potential of E. giganteum extracts as rich sources of phenolic compounds that can be used in the food, pharmaceutical and cosmetic fields.

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Background: Antibodies are essential part of vertebrates’ adaptive immune system; they can now be produced by transforming plants with antibody-coding genes from mammals/humans. Although plants do not naturally make antibodies, the plant-derived antibodies (plantibodies) have been shown to function in the same way as mammalian antibodies. Methods: PubMed and Google search engines were used to download relevant publications on plantibodies in medical and veterinary fields; the papers were reviewed and findings qualitatively described. Results: The process of bioproduction of plantibodies offers several advantages over the conventional method of antibody production in mammalian cells with the cost of antibody production in plants being substantially lesser. Contrary to what is possible with animal-derived antibodies, the process of making plantibodies almost exclusively precludes transfer of pathogens to the end product. Additionally, plants not only produce a relatively high yield of antibodies in a comparatively faster time, they also serve as cost-effective bioreactors to produce antibodies of diverse specificities. Conclusion: Plantibodies are safe, cost-effective and offer more advantages over animal-derived antibodies. Methods of producing them are described with a view to inspiring African scientists on the need to embrace and harness this rapidly evolving biotechnology in solving human and animal health challenges on the continent where the climate supports growth of diverse plants.

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To determine good ecological status and conservation of the Sub-Marine area of the Bay of Biscay, the implementation of a new rocky intertidal habitats monitoring is needed. A protocol has been adapted from the Brittany protocol for the water body FRFC11 "Basque coast" for the two indicators "intertidal macroalgae" and "subtidal macroalgae" under the Water Framework Directive to qualify the ecological. However no protocol has been validated for fauna in front of meridional characters of the benthic communities. Investigations carried out on macroalgae communities on intertidal area in WFD framework, since 2008, constitute an important working basis. This is the aim of the Bigorno project (Intertidal Biodiversity of the south of the Bay of Biscay and Observation for New search and Monitoring for decision support), financed by the Agency of Marine Protected Areas and the Departmental Council. To implement knowledge, a sampling protocol has been used in 2015 on the boulder fields of Guéthary. This site is part of Natura 2000 area "rocky Basque coast and offshore extension "It constitutes also a Znieff site and restricted fishing area. The sampling strategy considers the heterogeneity of substrates and the presence of intertidal microhabitats. Two main habitats are present: "mediolittoral rock in exposed area habitat" and "boulder fields". Habitat "intertidal pools and permanent ponds" is also present but, it is not investigated. Sampling effort is of 353 quadrats of 0.1 m², drawn randomly according to a spatially stratified sampling plan, defined by habitat and algal belts. Taxa identification and enumeration are done on each quadrat. The objective of this work is to expose results from data collected during 2015 sampling program. The importance of characterizing benthic fauna communities spatial distribution belonging to the Basque coast according to algal belts defines during the WDF survey was highlighted. Concurrently, indicators of biodiversity were studied.

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We discuss the concerns that the patenting activity in the new nanotechnologies could blur the line between what is considered a discovery and what can be considered as an invention. We find that the nature of nanotechnology products, research, and the development agendas in science and engineering fields that include biomimetics pose a challenge to the present practice of including chemicals as eligible patent subject matter. After revisiting the historical development of patent law and noting its divergence from the developments in science and technology, we introduce the distinction between simple and complex machines as these relate to chemistry and nanotechnology. This distinction poses the question of what is the logical category of inventions that fall within patentable subject matter given that patent law was conceived to cover simple machines, not complex ones.

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Reactive intermediates play an important the within the realm of chemical synthesis. Their high energy and transient nature make them difficult to observe and characterize, but it is these same properties that empower them to form bonds traditionally seen as difficult to prepare and unusual architectures quickly and efficiently. Herein, two reactive intermediates, arynes and transitient (2azaaryl)-cuprates, are exploited for their abilities to prepare important chemical motifs. Both serve as an avenue into the functionalization of arenes to provide products which hold value in a variety of fields including natural product total syntethis, pharmaseuticals and ligand design.

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This paper proposes a new framework for approaching Muslim women in sport, beyond the oft-utilised framework of sports development. In preference to a deficit model of sports participation, where marginalized groups and individuals are incorporated into mainstream culture as players of sport, we bring together three domains that remain under-investigated in terms of Muslim women and sport in Australia and internationally – participation, consumption and representation. By shifting the research focus toward the contribution of both active and passive sports participation to fostering pleasure, enjoyment and self-determination for Muslim women, possibilities emerge to expand on the narrow priority formulation and policy fields of ‘ethnicity’ and ‘well-being’ focused on physical health outcomes through which Muslim women and sports-based interventions are commonly framed.

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According to the DSM-IV- TR (American Psychiatric Association, 2000), one of the core deficits in autism is in the impairment of social interaction. Some have suggested that underlying these deficits is the reality that individuals with autism do not find social stimuli to be as reinforcing as other types of stimuli (Dawson, 2008). An interesting and growing body of literature supports the notion that symptoms in autism may be caused by a general reduction in social motivation (Chevallier et al., 2012). A review of the literature suggests that social orienting and social motivation are low in individuals with autism, and including social motivation as a target for therapeutic intervention should be pursued (Helt et al., 2008). Through our understanding of learning processes, researchers in behavior analysis and related fields have been able to use conditioning procedures to change the function of neutral or ineffective stimuli, including tokens (Ayllon & Azrin, 1968), facial expressions (Gewirtz & Pelaez-Nogueras, 1992) and praise (Dozier et al., 2012). The current study aimed to use operant and respondent procedures to condition social stimuli that were empirically shown to not be reinforcing prior to conditioning. Further, this study aimed to compare the two procedures in their effectiveness to condition social stimuli to function as reinforcers, and in their maintenance of effects over time. Using a multiple-baseline, multi-element design, one social stimulus was conditioned under each procedure to compare the different response rates following conditioning. Finally, the study sought to determine if conditioning social stimuli to function as reinforcers had any effect on the social functioning of young children with autism. Six children diagnosed with autism between the ages of 18 months and 3 years participated. Results show that the respondent procedure (pairing) resulted in more robust and enduring effects than the operant procedure (Sd procedure). Results of a social communication assessment (ESCS, Mundy et al., 2003) before and after conditioning demonstrate gains in all areas of social communication, particularly in the areas of initiating and responding to joint attention.

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Portugal is characterized by a significant asymmetry in the population distribution/density and economic activity as well as in social and cultural dynamics. This means very diverse landscapes, differences in regional development, sustainability and quality of life, mainly between urban and rural areas. A consequence coherent with the contemporary dynamics: urbanization of many rural areas that loose their productive-agricultural identity and, simultaneously, the reintegration in urban areas of spaces and activities with more rural characteristics. In this process of increasing complexity of organization of the landscape is essential to restore the continuum naturale (between urban and rural areas) allowing closer links to both ways of life. A strategy supported in the landscape, which plays important functions for public interest, in the cultural, social, ecological and environmental fields. At the same time, constitutes an important resource for economic activity, as underlined in the European Landscape Convention. Based on this assumption, and using a multi-method approach, the study aims to analyse a) the links between urban and rural areas in Portugal and b) the reasons why these territories are chosen by individuals as places of work and mobility, residence or evasion, culture and leisure, tranquillity or excitement – meaning overall well-being. Primary information was obtained by a questionnaire survey applied to a convenience sample of the Portuguese population. Secondary data and information will be collected on the official Portuguese Statistics (INE and PORDATA). Understanding the urban-rural links is essential to support policy measures, take advantage from the global changes and challenge many of the existing myths.