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251.
The continuous increase in world energy demand will lead to an energy crisis due to the limited availability of fossil fuels. Furthermore, the use of this energetic resource is responsible for the accumulation of greenhouse gases in atmosphere that is associated with several negative effects on environment. Therefore, it is worth to search for different energy supplies that are renewable and environmentally friendly—carbon neutral fuel. Microalgae are photosynthetic microorganisms that can achieve high oil contents. This oil is suitable for producing biodiesel; thus, microalgae are considered a promising sustainable energetic resource that can reduce the dependence on fossil fuel. Biodiesel production from microalgae includes several steps, such as cell cultivation and harvesting, oil extraction and biodiesel synthesis. Although several attempts have been made to improve biodiesel yields from microalgae, further studies are required to improve biodiesel production rates and to reduce the associated costs. This review shows the recent developments on biodiesel production from microalgae, emphasizing two process concepts: (1) indirect route, in which, after a facultative cell wall disruption method, microalgal oil is recovered in an appropriate solvent and then converted into biodiesel through transesterification and (2) direct route, in which biodiesel is produced directly from the harvested biomass. High biodiesel yields are obtained when both routes are preceded by a cell wall disruption method. In the indirect route, it is possible to apply three different types of solvents to recover microalgal oil. Although there are several concerns about the application of organic solvents, the most promising and cost-effective alternative for lipid recovery is n-hexane. Comparing direct and indirect routes, this study demonstrates that although further studies are required to optimize biodiesel production from microalgae, the available information proposes that the direct route is the most efficient. 相似文献
252.
Cañote Susan Johana Benites Barros Regina Mambeli Lora Electo Eduardo Silva dos Santos Ivan Felipe Silva Silva Ana Paula Moni Piñas Jean Agustin Velásquez Cañote Alexandra Lucitania Benites de Castro e Silva Hellen Luisa 《Journal of Material Cycles and Waste Management》2021,23(5):1810-1830
Journal of Material Cycles and Waste Management - This study aimed to carry out the Life Cycle Analysis (LCA) targeting to decide the better management system for sludge from both Activated Sludge... 相似文献
253.
Although the prevalence of employees working within the same workplace or occupation with their spouse has increased, relatively little research has examined their experiences. On the basis of the boundary and conservation of resources (COR) theories, we argue that higher levels of work–family role integration among work‐linked couples will lead to higher levels of spousal support resources and lower levels of work–family conflict. This will, in turn, lead to lower emotional exhaustion among employees in a work‐linked relationship. Among two samples of employees in a variety of occupations, we found that being in a work‐linked relationship was associated with both higher spousal instrumental support as well as different forms of work–family conflict. The interaction between spousal support and work–family conflict was associated with emotional exhaustion. We discuss the implications of these findings for boundary and COR theories in terms of movement of resources across work–family boundaries and resource relevance in the strain process. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
254.
255.
Biota as toxic metal indicators 总被引:4,自引:0,他引:4
Metal in the environment arises from both natural sources and human activities. Toxic metals in air, soil, and water have become a global problem. They are potential hazards to aquatic, animal, and human life because of their toxicity, bioaccumulative, and non-biodegradable nature. The major impacts of metal pollutants can be stated as ecosystem contamination and health problems of exposed human populations. Those problems have been a cause of increasing public concern throughout the world. Some trace metals are used by living organisms to stabilize protein structures, facilitate electron transfer reactions, and catalyze enzymatic reactions. But even metals that are biologically essential can be harmful to living organisms at high levels of exposure. An increasing concentration of heavy metals in the environment can modify mineral and enzyme functions of human beings. During the last two decades, the interest in using bioindicators as monitoring tools to assess environmental pollution with toxic metals has increased. Bioindicators are flora and fauna members, which are collected and analyzed to measure the levels of metal contaminants. Bioindicators therefore identify health hazards. Various living organisms, such as microbes, fungi, plants, animals, and humans, are used to monitor toxic metals from air, water, sediment, soil, and food chain. Here, we review recent bioindicators, toxicity assessment, and ecological effects. 相似文献
256.
Naghmeh Soltani Behnam Keshavarzi Armin Sorooshian Farid Moore Christina Dunster Ana Oliete Dominguez Frank J. Kelly Prakash Dhakal Mohamad Reza Ahmadi Sina Asadi 《Environmental geochemistry and health》2018,40(5):1785-1802
Concentrations of total suspended particulate matter, particulate matter with aerodynamic diameter <2.5 μm (PM2.5), particulate matter <10 μm (PM10), and fallout dust were measured at the Iranian Gol-E-Gohar Mining and Industrial Facility. Samples were characterized in terms of mineralogy, morphology, and oxidative potential. Results show that indoor samples exceeded the 24-h PM2.5 and PM10 mass concentration limits (35 and 150 µg m?3, respectively) set by the US National Ambient Air Quality Standards. Calcite, magnetite, tremolite, pyrite, talc, and clay minerals such as kaolinite, vermiculite, and illite are the major phases of the iron ore PM. Accessory minerals are quartz, dolomite, hematite, actinolite, biotite, albite, nimite, laumontite, diopside, and muscovite. The scanning electron microscope structure of fibrous-elongated minerals revealed individual fibers in the range of 1.5 nm to 71.65 µm in length and 0.2 nm to 3.7 µm in diameter. The presence of minerals related to respiratory diseases, such as talc, crystalline silica, and needle-shaped minerals like amphibole asbestos (tremolite and actinolite), strongly suggests the need for detailed health-based studies in the region. The particulate samples show low to medium oxidative potential per unit of mass, in relation to an urban road side control, being more reactive with ascorbate than with glutathione or urate. However, the PM oxidative potential per volume of air is exceptionally high, confirming that the workers are exposed to a considerable oxidative environment. PM released by iron ore mining and processing activities should be considered a potential health risk to the mine workers and nearby employees, and strategies to combat the issue are suggested. 相似文献
257.
Vitor H. Paiva Pedro Geraldes Iván Ramírez Ana Meirinho Stefan Garthe Jaime A. Ramos 《Marine Biology》2010,157(6):1385-1399
Many breeding seabird species are central-place foragers and constrained to find productive prey patches within their foraging
ranges. We assessed how different populations of a pelagic seabird species, the Cory’s shearwater Calonectris diomedea, breeding in oceanic and neritic conditions, cope with these constraints in the North Atlantic, during both incubation and
chick-rearing periods. We analysed 237 foraging trips to study the movements and oceanographic characteristics of foraging
habitats of seven different populations of Cory’s shearwaters. Generally, oceanic populations exhibited higher foraging effort,
by travelling more time and to more distant areas, and larger home ranges and feeding areas, than the neritic population (i.e.
breeding on an island within the Portuguese continental platform). On their short trips (i.e. ≤4 days), birds from the different
populations fed mostly in shallower waters around the colony. During long trips (i.e. ≥5 days), feeding areas of both oceanic
and neritic populations were characterized by high concentration values of chlorophyll-a, low sea-surface temperature and shallower habitats, with oceanic populations of the Azores exploiting areas north of the
islands over known seamounts and frontal regions. Birds from other oceanic population (Selvagens) also exploited the African
continental shelf system on their long trips. The home ranges of the different populations overlapped widely, but there was
a general spatial segregation in terms of the core feeding areas at the population level. Core feeding areas and areas of
foraging overlap between different populations should be important to inform conservation management measures, such as the
definition of Marine Important Bird Areas for seabirds over the North Atlantic. 相似文献
258.
Pacific lion-paw scallops were collected from natural aggregations in Laguna Ojo de Liebre (Pacific Ocean), the Gulf of California,
and from aquaculture facilities for genetic diversity analyses. Mitochondrial DNA sequencing uncovered two highly supported
clades separated by 2.5% divergence. Data from ten microsatellite markers suggest individuals from these mitogroups are introgressed,
raising questions about the mitotype origin. Some evidence suggests gene flow between La Paz and Ojo de Liebre; otherwise
the Gulf of California and Ojo de Liebre are acting as two distinct populations. It is unclear whether translocations between
sites have influenced the observed genetic structure or whether gene flow has been facilitated by past geologic events. Finally,
scallops spawned for aquaculture are unique from the wild and have significantly less diversity. These results warrant the
attention of managers and producers who should work to monitor and conserve genetic diversity in both wild and aquaculture
populations. 相似文献
259.
Ana P. L. Batista Hudson Wallace Pereira Carvalho Gustavo H. P. Luz Paulo F. Q. Martins Maraísa Gonçalves Luiz C. A. Oliveira 《Environmental Chemistry Letters》2010,8(1):63-67
A photocatalyst based on CuO/SiO2 was prepared, and evaluated for the degradation of methylene blue in aqueous medium. The photocatalyst was obtained by calcination
method of copper salt, in the presence of silica. The characterization by XRD, FTIR, and TPR techniques confirmed the formation
of CuO as active phase. SEM studies showed CuO deposited on the surface of SiO2. By ESI-MS, it was demonstrated that the degradation of methylene blue occurs through successive hydroxylations. Photodegradation
assays showed that CuO/SiO2 was efficient for degradation, and that the material worked better in the presence of UV light. 相似文献
260.
António O. Soares Danny Haelewaters Olga M. C. C. Ameixa Isabel Borges Peter M. J. Brown Pedro Cardoso Michiel D. de Groot Edward W. Evans Audrey A. Grez Axel Hochkirch Milada Holecová Alois Honěk Ján Kulfan Ana I. Lillebø Zdenka Martinková J. P. Michaud Oldřich Nedvěd Omkar Helen E. Roy Swati Saxena Apoorva Shandilya Arnaud Sentis Jiri Skuhrovec Sandra Viglášová Peter Zach Tania Zaviezo John E. Losey 《Conservation biology》2023,37(1):e13965
Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations. 相似文献