排序方式: 共有33条查询结果,搜索用时 421 毫秒
1.
Male and female weanling rats that were born to dams fed a diet low in linolenic acid received diets of 15% lipids by weight
containing 45% elaidic acid (as trielaidin) and 8.5% or 0.1% linolenic acid for 10 weeks. Four other groups, in which palmitic
or oleic acid replaced elaidic acid in the diet, served as controls. The fatty acid profiles of several lipid classes were
determined in adipose tissue, adrenals, testes, heart and brain. Elaidic acid was incorporated into tissue lipids in varying
degrees, depending on the organ and on the lipid class. Feeding elaidic acid induced no changes in the polyunsaturated fatty
acid (PUFA) profiles of testes lipids but resulted in definite modifications of the PUFA patterns of heart phosphatidylcholine
(PC) and phosphatidylethanolamine (PE). In linolenic acid-deprived rats, arachidonic acid was decreased in PC and linoleic
acid was increased in both PC and PE; 22∶5n−6 was strongly depressed in both PC and PE. In linolenic acid-fed rats, 22∶6n−3
was decreased in PC and PE. These changes, on the whole, were more evident in females, and some also were observed in adrenal
cholesteryl esters but only slightly in brain phospholipids. the apparent inhibition of the biosynthesis of PUFA induced by
dietary elaidic acid appeared to be complex and of greater intensity in the n−6 fatty acid series than in their n−3 homologues. 相似文献
2.
Mourad Ben Amor Pascal Lesage Pierre-Olivier Pineau Réjean Samson 《Renewable & Sustainable Energy Reviews》2010,14(9):2885-2895
Renewable distributed electricity generation can play a significant role in meeting today's energy policy goals, such as reducing greenhouse gas emissions, improving energy security, while adding supply to meet increasing energy demand. However, the exact potential benefits are still a matter of debate. The objective of this study is to evaluate the life cycle implications (environmental, economic and energy) of distributed generation (DG) technologies. A complementary objective is to compare the life cycle implications of DG technologies with the centralized electricity production representing the Northeastern American context. Environmental and energy implications are modeled according to the recommendations in the ISO 14040 standard and this, using different indicators: Human Health; Ecosystem Quality; Climate Change; Resources and Non-Renewable Energy Payback Ratio. Distinctly, economic implications are modeled using conventional life cycle costing. DG technologies include two types of grid-connected photovoltaic panels (3 kWp mono-crystalline and poly-crystalline) and three types of micro-wind turbines (1, 10 and 30 kW) modeled for average, below average and above average climatic conditions in the province of Quebec (Canada). A sensitivity analysis was also performed using different scenarios of centralized energy systems based on average and marginal (short- and long-term) technology approaches. Results show the following. First, climatic conditions (i.e., geographic location) have a significant effect on the results for the environmental, economic and energy indicators. More specifically, it was shown that the 30 kW micro-wind turbine is the best technology for above average conditions, while 3 kWp poly-crystalline photovoltaic panels are preferable for below average conditions. Second, the assessed DG technologies do not show benefits in comparison to the centralized Quebec grid mix (average technology approach). On the other hand, the 30 kW micro-wind turbine shows a potential benefit as long as the Northeastern American electricity market is considered (i.e., oil and coal centralized technologies are affected for the short- and long-term marginal scenarios, respectively). Photovoltaic panels could also become more competitive if the acquisition cost decreased. In conclusion, DG utilization will represent an improvement over centralized electricity production in a Northeastern American context, with respect to the environmental, energy and economic indicators assessed, and under the appropriate conditions discussed (i.e., geographical locations and affected centralized electricity production scenarios). 相似文献
3.
Regional and global integration initiatives push for more electricity sector integration everywhere in the world, including West Africa. The creation of the West African Power Pool (WAPP) in 2000 and important investments under this new structure in 2006 are concrete actions that will result in a more integrated West African electricity sector. But will this integrated sector be more functional than the previous ones? Will the identified electricity sector problems be solved with the new power pool? This paper analyzes how power sector integration is presented by international institutions (the UN Economic Commission for Africa, World Energy Council and World Bank) and identifies three problematic issues with the current integration approach: lack of African ownership, unclear and conflicting reform objectives and uncertainty of integration outcomes. 相似文献
4.
Chossegros L Hours M Charnay P Bernard M Fort E Boisson D Sancho PO Yao SN Laumon B 《Accident; analysis and prevention》2011,43(1):471-477
Background
This study sets out to identify risk factors for post-traumatic stress disorder (PTSD) after a road traffic accident with a view to improving prevention.Methods
The study used a prospective cohort of road traffic accident casualties. All subjects over 15 years of age were recruited in the course of an interview conducted while they were receiving care in a hospital of the Rhône area administrative département. Six months after their accident, they answered a self-administered postal questionnaire that included the Post-traumatic Check-List Scale (PCLS) in order to evaluate PTSD. Multivariate logistic regression analysis was conducted to compare those subjects with a PCLS score of 44 or over with those with a lower score, in order to identify factors that might be associated with PTSD.Results
592 subjects (out of 1168) returned the 6-month questionnaire and 541 completed the PCLS test. One hundred subjects had a PCLS score ≥44, suggesting PTSD, and 441 subjects did not. The factors associated with PTSD were initial injury severity, post-traumatic amnesia, the feeling of not being responsible for their accident and persistent pain 6 months after it. A lower odds-ratio was associated with users of two-wheel than four-wheel motor vehicles (OR = 0.4; 0.2–0.9).Conclusion
Besides predictive factors for PTSD (injury severity, post-traumatic amnesia and the feeling of not being responsible for their accident), our study suggested a reduced risk of PTSD among two-wheel motor vehicle users. 相似文献5.
Eva Ogire Olivier Diaz Pierre-Olivier Vidalain Vincent Lotteau Philippe Desprs Marjolaine Roche 《International journal of molecular sciences》2021,22(4)
La Reunion island in the South West Indian Ocean is now endemic for dengue following the introduction of dengue virus serotype 2 (DENV-2) cosmopolitan-I genotype in 2017. DENV-2 infection causes a wide spectrum of clinical manifestations ranging from flu-like disease to severe dengue. The nonstructural glycoprotein 1 (NS1) has been identified as playing a key role in dengue disease severity. The intracellular NS1 exists as a homodimer, whereas a fraction is driven towards the plasma membrane or released as a soluble hexameric protein. Here, we characterized the NS1 glycoproteins from clinical isolates DES-14 and RUN-18 that were collected during the DENV-2 epidemics in Tanzania in 2014 and La Reunion island in 2018, respectively. In relation to hepatotropism of the DENV, expression of recombinant DES-14 NS1 and RUN-18 NS1 glycoproteins was compared in human hepatoma Huh7 cells. We observed that RUN-18 NS1 was poorly stable in Huh7 cells compared to DES-14 NS1. The instability of RUN-18 NS1 leading to a low level of NS1 secretion mostly relates to lysine residues on positions 272 and 324. Our data raise the issue of the consequences of a defect in NS1 stability in human hepatocytes in relation to the major role of NS1 in the pathogenesis of the DENV-2 infection. 相似文献
6.
Assessing the economic value of renewable distributed generation in the Northeastern American market
Mourad Ben Amor Pierre-Olivier Pineau Caroline Gaudreault Réjean Samson 《Renewable & Sustainable Energy Reviews》2012,16(8):5687-5695
Incentive programs and tax rebates are commonly offered to offset the high initial costs of small-scale renewable energy systems (RES) and foster their implementation. However, the economic costs of RES grid integration must be fully known in order to determine whether such subsidies are justified. The objective of this paper is to assess the economic value of RES, including their environmental benefits, using hourly generation information in conjunction with hourly wholesale price data. Reaching the paper′s objective will provide a better estimate of the bias that could result from neglecting 1) the time pattern of the hourly wholesale price, 2) the impacts of carbon taxes on the hourly wholesale price and 3) the value of the marginal hourly GHG emissions. Selected RES include two types of grid-connected photovoltaic panels (3 kWp mono- and poly-crystalline) and three types of micro-wind turbines (1, 10 and 30 kW) modeled for different climatic conditions in the province of Quebec (Canada). The cost of electricity is based on the technical performance of these RES using a life cycle costing methodology. The economic value of RES electricity is estimated using the hourly wholesale electricity price in Northeastern American markets in 2006–2008. Results show that distributed generation (DG) has no economic benefits using the selected RES, even with a US$100/tonne of CO2-equivalent carbon tax. This finding remains the same when the value of the avoided GHG emissions is fully internalized, except for one scenario (micro-wind 30 kW). Our results are key to understanding the extent to which subsidies for distributed RES can be economically sustainable when the latter are integrated into regional networks driven by centralized electricity production. 相似文献
7.
Cuffe J Chávez E Shchepetov A Chapuis PO El Boudouti el H Alzina F Kehoe T Gomis-Bresco J Dudek D Pennec Y Djafari-Rouhani B Prunnila M Ahopelto J Sotomayor Torres CM 《Nano letters》2012,12(7):3569-3573
We report the changes in dispersion relations of hypersonic acoustic phonons in free-standing silicon membranes as thin as ~8 nm. We observe a reduction of the phase and group velocities of the fundamental flexural mode by more than 1 order of magnitude compared to bulk values. The modification of the dispersion relation in nanostructures has important consequences for noise control in nano- and microelectromechanical systems (MEMS/NEMS) as well as opto-mechanical devices. 相似文献
8.
Emilien Buet Jean-Baptiste Dubois Patrick Olier Ludovic Thilly Florence Lecouturier Pierre-Olivier Renault 《International Journal of Material Forming》2012,5(2):121-127
The structure refinement is a challenge for conductors used for the winding of resistive coils producing non-destructive pulsed magnetic fields over 80T. These nanocomposite conductors composed of a conducting multiscale Cu matrix embedding Nb reinforcing nanofilaments are usually manufactured by using a Severe Plastic Deformation (SPD) process based on hot extrusion, accumulative cold drawing and bundling (ADB) steps [Thilly et al. Philos Mag A 82:925, 2002]. Equal-channel angular extrusion (ECAE) is investigated here as an alternative route since it may provide faster refinement to obtain the ultrafine structure needed for optimized electrical and mechanical properties of the conductors. Therefore, copper-niobium specimens obtained by hot extrusion were processed by ECAE at room temperature. The specific die of the ECAE tool used here is constituted by a round channel with three angles corresponding to a total equivalent strain of about 2.5. Deformed samples were examined by optical microscopy and characterized by hardness profiles and x-ray diffraction (texture pole figures). After one ECAE-pass, the shape of the samples is modified but no trace of damage appeared at the Cu-Nb interfaces. An increase of the hardness values localized in the copper matrix is revealed whereas the hardness of the niobium remains unchanged. Prior to ECAE, the hot extrusion process induced a fibre texture for both copper and niobium. Two fibre texture components were observed for copper: <111> and <200>. A single <110> fibre texture component is evidenced for the niobium. After ECAE a significant variation of the texture is observed in relation with the strong shear induced by this process. 相似文献
9.
Worldwide electricity sector reforms open up electricity markets and increase trades. This has environmental consequences as exports and imports either increase or decrease local production and consequently greenhouse gas (GHG) emissions. This paper's objective is to illustrate the importance of electricity trade's impact on GHG emissions by providing an estimate of the net GHG emissions resulting from these trades. To achieve this objective, Quebec hourly electricity exchanges with adjacent jurisdictions were examined over the 2006–2008 period. In order to associate a specific GHG emission quantity to electricity trades, hourly marginal electricity production technologies were identified and validated using the Ontario hourly output per power plant and information released in the Quebec adjacent system operator reports. It is estimated that over three years, imports into Quebec were responsible for 7.7 Mt of GHG, while Quebec hydropower exports avoided 28.3 Mt of GHG emissions. Hence, the net result is 20.6 Mt of avoided emissions over 2006–2008, or about 7 Mt per year, which corresponds to more than 8% of the Quebec yearly GHG emissions. When GHG emissions from all life cycle stages (resource extraction to end-of-life) are accounted for, the net avoided GHG emissions increase by 35%, to 27.9 Mt. 相似文献
10.
Bagnaninchi PO Dikeakos M Veres T Tabrizian M 《IEEE transactions on nanobioscience》2004,3(4):243-250
In in vitro tissue engineering, microporous scaffolds are commonly used to promote cell proliferation and differentiation in three-dimensional structures. Classic measurement methods are particularly time consuming, difficult to handle, and destructive. In this study, a new nondestructive method based on complex permittivity measurement (CPM) is proposed to monitor and track the osteoblast and macrophage differentiation through their morphological variation upon cell attachment and proliferation inside the microporous scaffolds. CPM is performed using a vector network analyzer and a dielectric probe under sterile conditions in a laminar-flow hood. A suitable effective medium approximation (EMA) is applied to fit the data in order to extract the parameters of the different constituents. Our data show that the EMA depolarization factor can be monitored to assess the variation of cell morphology characterizing cell attachment. Discrimination between two batches of scaffolds seeded, respectively, with 2 million and 1 million osteoblast cells is possible; the ratio of their CPM-derived cell volume fractions is in agreement with the ratio of their cell seeding numbers. In addition, cell proliferation inside scaffolds seeded with osteoblasts cultured in alpha minimum essential medium and inside scaffolds seeded with osteoblasts cultured in alpha minimum essential medium supplemented to induce the formation of extracellular matrix is monitored via CPM over several days. CPM-determined cell volume fraction is compared to DNA assay cell counts. Extracellular matrix formation and cell presence was confirmed by scanning electron microscopy. A set of three signature parameters (epsilon'mem, epsilon'cyt, kappa'cyt) characteristic of cell line is extracted from CPM. Distinct signatures are recorded for osteoblasts and macrophages, thus confirming the ability of CPM to discriminate between different cell types. This study demonstrates the potential of CPM as a diagnostic tool to monitor quickly and noninvasively cell growth and differentiation inside microporous scaffolds. Our findings suggest that the use of CPM could be extended to many biomedical applications, such as drug detection and automation of tissue and bacterial cultures in bioreactors. 相似文献