4,256 research outputs found

    Functionalization of synthetic talc-like phyllosilicates by alkoxyorganosilane grafting

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    A range of talc-like phyllosilicates were prepared via a hydrothermal synthesis performed at five different temperatures from 160 to 350 °C. The organization of the lattice and the degree of crystallinity of the new materials were evaluated by different techniques such as XRD, FTIR, solid-state 29Si NMR, TEM, FEG-SEM and TG-DTA. When synthesized at low temperature the material presents high degree of hydration, low crystallinity and flawed structure. This was attributed to stevensite-talc interstratified product present in the samples. The stevensite/talc ratio and the hydration decrease in the talc-like phyllosilicate samples when the hydrothermal synthesis temperature increases and so the crystallinity becomes higher. A thermal treatment at 500 °C allowed a significant flaw reduction in talc-like phyllosilicate structure; the synthesized sample at 350 °C and heat treated presents a structure close to that of talc. The different talc-like phyllosilicates were grafted covalently by two organoalkoxysilane reagents, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole (IM2H) and 2-hydroxy-4-(3-triethoxysilylpropoxy)-diphenylketone (HTDK). The grafted amounts of the hybrids, determined by elemental analysis and confirmed by thermogravimetric data, are dependent on the hydrothermal synthesis temperature and organoalkoxysilanes; they become smaller when the synthesis temperature increases and when HTDK is used. FTIR and solid-state 13C CP MAS NMR were applied to characterize the grafted organic groups. So, in this work it is shown that by choosing the hydrothermal synthesis temperature or by performing an additional annealing it is possible to adjust the amount of defects in the structure of talc-like phyllosilicates which seems to be strongly correlated to the grafting performance

    Characterization of aromaticity in analogues of titan's atmospheric aerosols with two-step laser desorption ionization mass spectrometry

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    The role of polycyclic aromatic hydrocarbons (PAH) and Nitrogen containing PAH (PANH) as intermediates of aerosol production in the atmosphere of Titan has been a subject of controversy for a long time. An analysis of the atmospheric emission band observed by the Visible and Infrared Mapping Spectrometer (VIMS) at 3.28 micrometer suggests the presence of neutral polycyclic aromatic species in the upper atmosphere of Titan. These molecules are seen as the counter part of negative and positive aromatics ions suspected by the Plasma Spectrometer onboard the Cassini spacecraft, but the low resolution of the instrument hinders any molecular speciation. In this work we investigate the specific aromatic content of Titan's atmospheric aerosols through laboratory simulations. We report here the selective detection of aromatic compounds in tholins, Titan's aerosol analogues, produced with a capacitively coupled plasma in a N2:CH4 95:5 gas mixture. For this purpose, Two-Step Laser Desorption Ionization Time-of-Flight Mass Spectrometry (L2DI-TOF-MS) technique is used to analyze the so produced analogues. This analytical technique is based on the ionization of molecules by Resonance Enhanced Multi-Photon Ionization (REMPI) using a {\lambda}=248 nm wavelength laser which is selective for aromatic species. This allows for the selective identification of compounds having at least one aromatic ring. Our experiments show that tholins contain a trace amount of small PAHs with one to three aromatic rings. Nitrogen containing PAHs (PANHs) are also detected as constituents of tholins. Molecules relevant to astrobiology are detected as is the case of the substituted DNA base adenine

    Second-harmonic microscopy of unstained living cardiac myocytes: measurements of sarcomere length with 20-nm accuracy.

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    International audienceWe extend second-harmonic generation (SHG) microscopy to the measurement of sarcomere length in unstained living cardiac myocytes with 20-nm accuracy. We quantify individual sarcomere shortening in the presence of saxitoxin and find that it is in agreement with mechanical measurements of atrial tissue contracture. This functional application of SHG microscopy is generally applicable to quantify the physiological effects of drugs on contractile tissue. Our data also suggest that packed myosin heads in sarcomere thick filaments are responsible for the large second-harmonic endogenous signal in muscle tissue

    A survey of the transmission of infectious diseases/infections between wild and domestic ungulates in Europe

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    The domestic animals/wildlife interface is becoming a global issue of growing interest. However, despite studies on wildlife diseases being in expansion, the epidemiological role of wild animals in the transmission of infectious diseases remains unclear most of the time. Multiple diseases affecting livestock have already been identified in wildlife, especially in wild ungulates. The first objective of this paper was to establish a list of infections already reported in European wild ungulates. For each disease/infection, three additional materials develop examples already published, specifying the epidemiological role of the species as assigned by the authors. Furthermore, risk factors associated with interactions between wild and domestic animals and regarding emerging infectious diseases are summarized. Finally, the wildlife surveillance measures implemented in different European countries are presented. New research areas are proposed in order to provide efficient tools to prevent the transmission of diseases between wild ungulates and livestock

    Potential of multi-species livestock farming to improve the sustainability of livestock farms: A review.

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    Diversified farming systems are proposed as a major mechanism to address the many sustainability issues of today's agriculture. Multi-species livestock farming, i.e. keeping two or more animal species simultaneously on the same farm, is an option that has received little attention to date. Moreover, most studies of multi-species livestock farming are limited, usually focusing on selected dimensions of farm sustainability and addressing lower organizational levels (i.e. within the farm) and rather limited time horizons (e.g. a few weeks in a grazing season). Thus, a comprehensive assessment of multi-species livestock farming in terms of farm sustainability is lacking. In this context, we outline and discuss potential benefits and limitations of multi-species livestock farming for livestock farm sustainability from existing literature and list issues on multi-species livestock farming requiring further research. We show that multi-species livestock farming has the potential to improve the three dimensions of sustainability reviewed - economic viability for farmers, environmental soundness and social acceptability by being respectful of animals and humans - as long as locally relevant farming practices are implemented, especially an appropriate stocking rate during grazing. If relevant practices are not observed, multi-species livestock farming may produce undesirable effects, such as competition for resource acquisition during grazing, parasitic cross-infection and more intense work peaks. Therefore, we identify four focal research areas for multi-species livestock farming. First, characterizing the management of multi-species livestock farms. To do this, we suggest considering the integration of production enterprises (e.g. cattle and sheep enterprises) within the farm from three perspectives: farming practices (e.g. grazing management), work organization and sales. Second, exploring the complementarity of livestock species on multi-species livestock farms. This is especially true for species combinations that have been largely ignored (e.g. ruminants and monogastrics), even though they may have potential due to complementary diet compositions and resource-acquisition strategies. Third, assessing the sustainability of multi-species livestock farm scenarios (current or alternative) according to the management practices and production conditions, which requires adapting existing methods/models or developing new ones. Fourth, characterizing conditions for success and obstacles for multi-species livestock farming along the value chain from production to consumption, considering stakeholders' objectives, work habits and constraints. Increasing understanding should help prioritize actions and organize them to scale up multi-species livestock farming

    Living with an acquired brain injury. Barriers and facilitators to developing community supports as a basis for independent living: the experiences and perceptions of people with acquired brain injury

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    This study found that natural community supports were comprised of two distinct groupings; firstly immediate families, friends and peer support groups; secondly neighbours and local community groups such as sporting and activity- based organisations and groups. The findings of this study indicate that living with acquired brain injury involves a process where the person moves from acute high intensity health services onto rehabilitative services and then onto re-establishing independent lives. It is evident that smooth transitions and interconnectivity of services are essential in facilitating this recovery process. Instrumental to the recovery is the support of immediate family and close friends, who form people’s immediate natural support network and go a long way towards facilitating individuals in rebuilding their lives. A key finding of this study is that broader natural community supports do not appear to play as central a role in supporting individuals to live independent lives when compared to the role of family and friends. The lack of involvement of broader community groups, in many ways, prompted individuals to contact formal support services. For the majority of participants, independence is facilitated through the combination of immediate natural community supports and formal services. The role of formal support services is key to developing broader community support networks. This study found a blurred division between formal services and broader community support networks. The authors recommended that the role of formal supports services in acting as a bridge between the needs of the individual and the development of meaningful community networks, be formally recognised and further developed. Additionally, they argued that the importance of the role of broader natural community, supports such as those provided by community and sporting groups must be enhanced. Greater awareness of the issues faced by people living with acquired brain injury and its often invisible nature is necessary in this endeavour. The authors stated it is important to recognise that there are multiple issues impacting on independent living and these issues intersect, for instance with age, gender, employment, qualifications and so on. A lack of public awareness of acquired brain injury was found to be a key barrier to independent living, along with issues relating to socialising, access to employment and finances. The findings of this study reflect the complexities of living with acquired brain injury and the need for holistic support that is cognisant of the factors which impact on integration. It is vital that flexible, personalised services are developed which are fit for purpose and meet the needs of not only people with acquired brain injury but also their immediate natural community support network. Recognition of the intersection between immediate/ broader natural community supports and formal services is also key to developing the comprehensive and practical supports required to achieve an independent life. This was a qualitative study and all participants were sourced through Headway, a community based service provider for people with ABI. Data collection was divided into two stages: firstly focus groups, followed by individual interviews. Four focus groups were convened in Cork (2), Dublin (1) and Limerick (1). Each focus group was facilitated by at least two members of the research team and a total of twenty-six individuals participated in the focus groups. Thematic analysis of the data was undertaken to guide and inform the second stage of the study; the individual interviews. Ten interviews were undertaken with individuals who presented with ABI in the Cork and Limerick regions

    Report of IRPA task group on the impact of the eye lens dose limits

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    In 2012 IRPA established a task group (TG) to identify key issues in the implementation of the revised eye lens dose limit. The TG reported its conclusions in 2013. In January 2015, IRPA asked the TG to review progress with the implementation of the recommendations from the early report and to collate current practitioner experience. This report presents the results of a survey on the view of the IRPA professionals on the new limit to the lens of the eye and on the wider issue of tissue reactions. Recommendations derived from the survey are presented. This report was approved by IRPA Executive Council on 31 January 2017

    CONTRIBUTIONS DES PARTENARIATS POUR CONCEVOIR DES CONNAISSANCES AGRONOMIQUES SUR LA GESTION DE L'HERBE ET DEVELOPPER DES OUTILS ACTIONNABLES PAR DES CONSEILLERS FOURRAGERS

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    N° ISBN - 978-2-7380-1284-5International audienceCo-design of artifacts usable by extension services can be a long-lasting task. It partly depends on the developments of scientific knowledge. In addition, as we will show in this testimony, training and partnership with practitioners play a key role in the design of an artifact, here a tool to diagnose the opportunity of grassland management practices in a farm. Discussions between researchers and practitioners during training sessions led to the design of prototypes of articfact. Partnership between researchers and practitioners on the long term contributed to adjust the artifact, to simplify its procedure, and overall to improve its diagnosis capacity by capitalizing on researchers' and practitioners' knowledge. This experience has required adaptive capacity of researchers, leading them to adopt different research postures according to the stages in the interactions with practitioners. Researchers considered practitioners as knowledge providers by associating them to articfact co-design, or as experts to be equipped by involving them in participatory research projects
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