Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.421
Filtrar
1.
Barbarói ; (58): 8-29, jan.-jun. 2021.
Artículo en Portugués | LILACS, Index Psicología - Revistas técnico-científicas | ID: biblio-1150659

RESUMEN

O presente artigo resulta de uma pesquisa intervenção de cunho qualitativo, realizada com quinze adolescentes de uma instituição localizada litoral norte de Santa Catarina. Para coleta de dados foram realizadas oficinas musicais, nas quais os participantes escolheram letras de músicas para abordar questões a respeito de sua condição de vida, discorrendo sobre o território onde vivem, a percepção que têm de si e do tempo e sobre as suas redes sociais de apoio. Em um corte temático para efeitos deste artigo, as redes sociais de apoio foram eleitas como a temática a ser analisada e discutida por meio da análise temático-categorial. Os resultados apontaram para um espaço escolar com uma função indefinida, pautado na contestação das regras e normas que são impostas, onde ocorrem brincadeiras e intrigas. Quanto à rede de amigos, observou-se que essa relação é baseada nos sentimentos de confiança e de lealdade, se configurando como uma rede essencial nesse ciclo da vida, assim como a família que se apresenta como um fator de proteção, mesmo perpassando situações conflituosas, de violência, mortes e separações.(AU)


The proposal of this paper is a result from a qualitative intervention research conducted with fifteen teenagers from an institution located north coast of Santa Catarina. For data collection, music workshops were made and the participants chose music lyrics that address questions about their life condition, talking about the place where they live, their perception of themselves, their perception of the time and of the social support networks. In a cutting theme for the proposes of this article, the social support networks were chosen as the theme to be analyzed and discussed by thematic-categorical analysis. The results pointed to a school area with an undefined function, based on the contestation of the rules and regulations that are imposed, where the games and intrigues happen. Referring to the friends network, observed that this relation is based on feelings of trust and loyalty, setting up as a essential network in the life cycle, as well as the family that presents itself as a protective factor, even through conflict situations , violence, deaths an separations.(AU)


El presente artículo es el resultado de una investigación de intervención con enfoque cualitativo, realizada con quince adolescentes de una institución localizada en litoral norte de Santa Catarina. Para la coleta de dados fueron realizados talleres musicales, en los cuales los miembros preferirán letras de canciones que enfoquen cuestiones con respecto a su condición de vida, disertando sobre los lugares donde viven, la percepción que tienen de sí propio, del tiempo y sus redes de apoyo social. En un tema de corte para los efectos de este artículo, se eligieron las redes de apoyo social como el tema para ser analizado y debatido por el análisis de temáticas-categóricas. Los resultados apuntaron para un espacio escolar con una función indefinida, pautado en la contestación de las reglas y normas que son impuestas, donde hay juegos y chismes. Cuanto a la rede de amistades, se ha observado que esta relación se basa en los sentimientos de confianza y de lealtad, se perfila como una red esencial en el ciclo de vida, así como la familia es presentada como un factor de protección, incluso impregna situaciones contradictorias, con violencia, muertes y separaciones.(AU)


Asunto(s)
Humanos , Adolescente , Apoyo Social , Adolescente , Red Social , Música , Factores Protectores , Relaciones Interpersonales , Estadios del Ciclo de Vida
2.
Sci Total Environ ; 773: 145573, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33940733

RESUMEN

In Colombia, the beef production chain accounts for approximately 11.6 million cattle heads and annually produces 933 million kg of the beef carcass. There are no life cycle assessment (LCA) studies that have evaluated the environmental performance of Colombian beef systems. The present study aimed to estimate the carbon footprint (CF), non-renewable energy use, and land use of 251 cow-calf and 275 fattening farms in Colombia. The study also aimed to identify the main hotspots of adverse environmental impacts and propose possible mitigation options and their cost-effectiveness. The impact categories were estimated using the 2006 IPCC and the 2019 Refinement to 2006 IPCC guidelines, databases, and locally estimated emission factors. The functional units used were 1 kg fat and protein corrected milk (FPCM) and 1 kg live weight gain (LWG), leaving the farm gate. Three methods of allocating environmental burdens to meat and milk products were applied: economic, energy, and mass allocation. The adoption of improved pastures was considered a mitigation measure, and an economic assessment was performed to estimate the relative cost-effectiveness of its establishment. A principal component multivariate analysis and a Hierarchical Clustering on Principal Components were performed. The economic allocation method assigned a greater environmental burden to meat (83%), followed by energy content (80%) and mass production (73%). The largest sources of GHG emissions were enteric fermentation and manure deposited on pasture. Both cow-calf and fattening systems had a cluster of farms with better productivity, pasture and cattle management practices, and environmental performance. The CF for meat could be reduced by 33 to 56% for cow-calf and 21 to 25% for fattening farms, by adopting improved pastures. Therefore, our results suggest that GHG emissions can be reduced by adopting improved pastures, better agricultural management practices, efficient fertilizer usage, using the optimal stocking rate, and increasing productivity.


Asunto(s)
Huella de Carbono , Industria Lechera , Animales , Bovinos , Colombia , Femenino , Estadios del Ciclo de Vida , Leche
3.
Dis Aquat Organ ; 144: 143-150, 2021 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-33955852

RESUMEN

In this study, we describe in detail the life cycle of Tachaea chinensis (Isopoda: Corallanidae), a branchial ectoparasitic isopod that infests the freshwater shrimp Palaemonetes sinensis in China. We obtained 14 ovigerous T. chinensis females (8.22-11.92 mm in length) and observed the development of embryos through 5 sequential ontogenetic stages within the brood pouches (marsupium) of these females. The number of eggs or mancae (post-larval juveniles) held in the female marsupium ranged from 31 to 86, with a mean ± SD of 61.25 ± 16.16 eggs. Female T. chinensis were semelparous, i.e. individuals died following the release of mancae from the marsupium. Released mancae were non-planktonic and immediately infective to host shrimps. However, only a few mancae successfully established contact with a host, and it is thus assumed that the remainder were predated by shrimp. Attached T. chinensis fed on the host hemolymph, and subsequent to host death, these isopods typically searched for a new host. We also found that T. chinensis exhibits a host preference: most mancae attached to P. sinensis rather than to Neocaridina sp. or Macrobrachium nipponense. This study provides valuable empirical data that will support future research on the prevention and control of parasitic isopod infections.


Asunto(s)
Isópodos , Palaemonidae , Animales , China , Femenino , Agua Dulce , Interacciones Huésped-Parásitos , Estadios del Ciclo de Vida
4.
Nat Commun ; 12(1): 2395, 2021 04 22.
Artículo en Inglés | MEDLINE | ID: mdl-33888695

RESUMEN

The infraorder Brachyura (true or short-tailed crabs) represents a successful group of marine invertebrates yet with limited genomic resources. Here we report a chromosome-anchored reference genome and transcriptomes of the Chinese mitten crab Eriocheir sinensis, a catadromous crab and invasive species with wide environmental tolerance, strong osmoregulatory capacity and high fertility. We show the expansion of specific gene families in the crab, including F-ATPase, which enhances our knowledge on the adaptive plasticity of this successful invasive species. Our analysis of spatio-temporal transcriptomes and the genome of E. sinensis and other decapods shows that brachyurization development is associated with down-regulation of Hox genes at the megalopa stage when tail shortening occurs. A better understanding of the molecular mechanism regulating sexual development is achieved by integrated analysis of multiple omics. These genomic resources significantly expand the gene repertoire of Brachyura, and provide insights into the biology of this group, and Crustacea in general.


Asunto(s)
Adaptación Fisiológica/genética , Braquiuros/fisiología , Regulación del Desarrollo de la Expresión Génica , Genoma/genética , Animales , Acuicultura , Mapeo Cromosómico , Femenino , Fertilidad/genética , Perfilación de la Expresión Génica , Genes Homeobox/genética , Genómica , Especies Introducidas , Estadios del Ciclo de Vida/genética , Masculino , Familia de Multigenes/genética , Osmorregulación/genética , Desarrollo Sexual/genética , Análisis Espacio-Temporal , Secuenciación Completa del Genoma
5.
Nutrients ; 13(3)2021 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-33803760

RESUMEN

The role of docosahexaenoic acid (DHA) and arachidonic acid (AA) in neurogenesis and brain development throughout the life cycle is fundamental. DHA and AA are long-chain polyunsaturated fatty acids (LCPUFA) vital for many human physiological processes, such as signaling pathways, gene expression, structure and function of membranes, among others. DHA and AA are deposited into the lipids of cell membranes that form the gray matter representing approximately 25% of the total content of brain fatty acids. Both fatty acids have effects on neuronal growth and differentiation through the modulation of the physical properties of neuronal membranes, signal transduction associated with G proteins, and gene expression. DHA and AA have a relevant role in neuroprotection against neurodegenerative pathologies such as Alzheimer's disease and Parkinson's disease, which are associated with characteristic pathological expressions as mitochondrial dysfunction, neuroinflammation, and oxidative stress. The present review analyzes the neuroprotective role of DHA and AA in the extreme stages of life, emphasizing the importance of these LCPUFA during the first year of life and in the developing/prevention of neurodegenerative diseases associated with aging.


Asunto(s)
Ácido Araquidónico/farmacología , Ácidos Docosahexaenoicos/farmacología , Estadios del Ciclo de Vida/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Nutrientes/farmacología , Envejecimiento/efectos de los fármacos , Encéfalo/efectos de los fármacos , Humanos , Enfermedades Neurodegenerativas/metabolismo , Neurogénesis/efectos de los fármacos , Transducción de Señal/efectos de los fármacos
6.
Artículo en Inglés | MEDLINE | ID: mdl-33808638

RESUMEN

This study attempted to explore the competitive advantage strategies of the medical consumables industry (MCI) from the perspectives of human resources, research and development (R&D) and the industry life cycle. As one of the essential branches of modern medical device industry, the MCI has developed rapidly in recent years as global demand for medical consumables has shown continual growth, but it also faces market uncertainty. This study took Taiwan's small/medium medical consumables enterprises (SMMCEs) as a sample, and used the translog revenue function to study the competitive advantage of the MCI through human resource and R&D investment strategies and the stage characteristics of the industry life cycle curve. The results showed that the various human resources and R&D expenses of the small/medium medical consumables industry (SMMCI) can interact with each other to influence total revenue and that the SMMCI needs more varied types of human resources to enhance its competitive advantage. The total revenue of the SMMCI decreased as education inputs rose, but it increased along with increases in the number of employee and R&D inputs. Observed from the life cycle curve of the SMMCI, total revenue increased rapidly during the startup and growth stages, increased slowly during the maturity stage, and decreased during the decline stage. Finally, we put forward competitive advantage strategies and management suggestions for medical consumables enterprises (MCEs). We are the first to document the life cycle curve and competitive advantage strategies of the MCI, thereby contributing to the related literature.


Asunto(s)
Industrias , Investigación , Animales , Humanos , Estadios del Ciclo de Vida , Estudios Longitudinales , Recursos Humanos
8.
Viruses ; 13(4)2021 04 09.
Artículo en Inglés | MEDLINE | ID: mdl-33918958

RESUMEN

Therapeutic options for coronaviruses remain limited. To address this unmet medical need, we screened 5406 compounds, including United States Food and Drug Administration (FDA)-approved drugs and bioactives, for activity against a South Korean Middle East respiratory syndrome coronavirus (MERS-CoV) clinical isolate. Among 221 identified hits, 54 had therapeutic indexes (TI) greater than 6, representing effective drugs. The time-of-addition studies with selected drugs demonstrated eight and four FDA-approved drugs which acted on the early and late stages of the viral life cycle, respectively. Confirmed hits included several cardiotonic agents (TI > 100), atovaquone, an anti-malarial (TI > 34), and ciclesonide, an inhalable corticosteroid (TI > 6). Furthermore, utilizing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we tested combinations of remdesivir with selected drugs in Vero-E6 and Calu-3 cells, in lung organoids, and identified ciclesonide, nelfinavir, and camostat to be at least additive in vitro. Our results identify potential therapeutic options for MERS-CoV infections, and provide a basis to treat coronavirus disease 2019 (COVID-19) and other coronavirus-related illnesses.


Asunto(s)
Antivirales/farmacología , Coronavirus del Síndrome Respiratorio de Oriente Medio/efectos de los fármacos , Coronavirus del Síndrome Respiratorio de Oriente Medio/aislamiento & purificación , /efectos de los fármacos , Adenosina Monofosfato/análogos & derivados , Adenosina Monofosfato/farmacología , Alanina/análogos & derivados , Alanina/farmacología , Animales , Infecciones por Coronavirus/virología , Aprobación de Drogas , Evaluación Preclínica de Medicamentos , Reposicionamiento de Medicamentos , Sinergismo Farmacológico , Humanos , Estadios del Ciclo de Vida/efectos de los fármacos , Coronavirus del Síndrome Respiratorio de Oriente Medio/crecimiento & desarrollo , Bibliotecas de Moléculas Pequeñas/farmacología
9.
Parasite ; 28: 34, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33835020

RESUMEN

The coquina, Donax variabilis, is a known intermediate host of monorchiid and gymnophallid digeneans. Limited morphological criteria for the host and the digeneans' larval stages have caused confusion in records. Herein, identities of coquinas from the United States (US) Atlantic coast were verified molecularly. We demonstrate that the current GenBank sequences for D. variabilis are erroneous, with the US sequence referring to D. fossor. Two cercariae and three metacercariae previously described in the Gulf of Mexico and one new cercaria were identified morphologically and molecularly, with only metacercariae occurring in both hosts. On the Southeast Atlantic coast, D. variabilis' role is limited to being a facultative second intermediate host, and D. fossor, an older species, acts as both first and second intermediate hosts. Sequencing demonstrated 100% similarities between larval stages for each of the three digeneans. Sporocysts, single tail cercariae, and metacercariae in the incurrent siphon had sequences identical to those of monorchiid Lasiotocus trachinoti, for which we provide the complete life cycle. Adults are not known for the other two digeneans, and sequences from their larval stages were not identical to any in GenBank. Large sporocysts, cercariae (Cercaria choanura), and metacercariae in the coquinas' foot were identified as Lasiotocus choanura (Hopkins, 1958) n. comb. Small sporocysts, furcocercous cercariae, and metacercariae in the mantle were identified as gymnophallid Parvatrema cf. donacis. We clarify records wherein authors recognized the three digenean species but confused their life stages, and probably the hosts, as D. variabilis is sympatric with cryptic D. texasianus in the Gulf of Mexico.


Asunto(s)
Bivalvos , Trematodos , Animales , Cercarias , Estadios del Ciclo de Vida , Metacercarias , Trematodos/genética
10.
Braz J Biol ; 82: e237351, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33852649

RESUMEN

Cladocerans are a diverse group of species that show rapid responses to changes in environmental conditions. This adaptive capacity has important implications for egg production and life cycle, especially in transitory environments such as temporary waterbodies. The present study investigated the life history and egg production of Alona gutatta Sars, 1862 (Crustacea, Cladocera), an abundant and frequent species from a high-altitude temporary pond (Lagoa Seca, Minas Gerais, Brazil). Newly hatched neonates were monitored in relation to time of maturation, number of eggs produced per female and time of survival. Neonates required a mean of 8 days to mature. A. guttata survived for a mean of 30.9 ± 8.1 days and produced 2 eggs per brood, generating a mean of 10.95 ± 6.41 neonates during the entire life cycle. The rapid development, short time to produce eggs and long life cycle are important adaptations to the adverse environmental conditions of temporary aquatic environments, which can contribute to the rapid colonization of Alona guttata in transitory ecosystems.


Asunto(s)
Cladóceros , Animales , Brasil , Ecosistema , Femenino , Humanos , Recién Nacido , Estadios del Ciclo de Vida , Estanques
11.
Mem Inst Oswaldo Cruz ; 116: e200571, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33681890

RESUMEN

Leishmania infantum chagasi is the causative agent and Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the Americas. We investigated the expression of Leishmania genes within L. longipalpis after artificial infection. mRNAs from genes involved in sugar and amino acid metabolism were upregulated at times of high parasite proliferation inside the insect. mRNAs from genes involved in metacyclogenesis had higher expression in late stages of infection. Other modulated genes of interest were involved in immunomodulation, purine salvage pathway and protein recycling. These data reveal aspects of the adaptation of the parasite to the microenvironment of the vector gut and reflect the preparation for infection in the vertebrate.


Asunto(s)
Insectos Vectores/parasitología , Leishmania infantum/genética , Leishmania/aislamiento & purificación , Leishmaniasis Visceral/transmisión , Psychodidae/parasitología , Animales , Brasil , Expresión Génica , Leishmaniasis Visceral/epidemiología , Leishmaniasis Visceral/parasitología , Estadios del Ciclo de Vida , Psychodidae/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos
12.
Waste Manag ; 124: 314-324, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33647557

RESUMEN

Municipal solid waste (MSW) management is an important challenge in developing and emerging countries, where two realities co-exist. On the one hand, their metropolitan cities exhibit an integrated MSW system with a specialized fleet for the collection and landfills for the final disposal, concentrating on environmental initiatives such as municipal recycling programs. On the other hand, their regional cities show an MSW system based on adapted transports for collection and open dumps for final disposal. Besides, they face other environmental problems due to local conditions. This research proposes a life cycle assessment (LCA) approach to close the gap between these two realities. In particular, we study the city of Valdivia (Chile), one of the main regional capitals of South America, which shares similarities with other southern regional cities in the Global South. This city disposes 95% of its MSW in open dumps and presents one of the highest environmental pollution rates in Latin America. We analyze the greenhouse gas (GHG) emissions and energy performance of six scenarios, seeking a solution for these problems. The results obtained show that a waste-to-energy scenario would generate savings of GHG emission and particulate matter, reaching 11.3% and 21.8%, respectively. Using our LCA approach, we can provide environmental evidence to highlight the importance of improving MSW management in regional cities, closing the gap with MSW management in metropolitan cities, and contributing to national targets such as United Nations Sustainable Development Goals and Nationally-Determined Contributions.


Asunto(s)
Eliminación de Residuos , Administración de Residuos , Animales , Ciudades , Países en Desarrollo , Estadios del Ciclo de Vida , Residuos Sólidos/análisis , América del Sur
13.
Environ Sci Technol ; 55(8): 4324-4331, 2021 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-33760596

RESUMEN

Criticality and supply risk models seek to address concerns of potential disruption to global metal supply. These models need to incorporate disruption events that arise from within the mining industry's market structure. In this paper, we review what we refer to as events of "mine life cycle disruption". These include project abandonments, premature closures, care and maintenance, and ownership changes. Life cycle disruptions not only cause production disruptions but also embed social and environmental risks in global metal markets. They arise from the highly variable business environment in which the resources sector operates. Changing commodity prices directly influence mining revenues and drive decisions on whether to halt or push forward a project. While some disruptions are involuntary and induced by external economic conditions, others are purposefully triggered by certain mining companies that use them to their advantage. We examine the frequency of these disruptions based on a contemporary global inventory of 35,000 mining projects and present the findings against recent developments in the research literature. We conclude that life cycle disruption events are an important consideration in balancing the demand for metals and the social and environmental impacts of mining and propose pathways for managing these events and their effects.


Asunto(s)
Minería , Propiedad , Animales , Ambiente , Estadios del Ciclo de Vida , Metales
14.
Ecotoxicol Environ Saf ; 215: 112143, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33740489

RESUMEN

Risk assessment of pesticides involves ecotoxicological testing. In case pesticide exposure to bees is likely, toxicity tests are performed with honey bees (Apis mellifera), with a tiered approach, for which validated and internationally accepted test protocols exist. However, concerns have grown regarding the protection of non-Apis bees [bumble bees (Bombus spp.), solitary and stingless bees], given their different life cycles and therefore distinct exposure routes. Larvae of solitary bees of the genus Osmia feed on unprocessed pollen during development, yet no toxicity test protocol is internationally accepted or validated to assess the impact of pesticide exposure during this stage of their life cycle. Therefore, the purpose of this study is to further validate a test protocol with two solitary bee species (O. cornuta and O. bicornis) to assess lethal and sublethal effects of pesticide exposure on larval development. Larvae were exposed to thiacloprid (neonicotinoid insecticide) mixed in a new, artificial pollen provision. Both lethal (developmental and winter mortality) and sublethal endpoints (larval development time, pollen provision consumption, cocoon weight, emergence time and adult longevity) were recorded. Effects of lower, more environmentally realistic doses were only reflected in sublethal endpoints. In both bee species, thiacloprid treatment was associated with increased developmental mortality and larval development time, and decreased pollen provision consumption and cocoon weight. The test protocol proved valid and robust and showed that for higher doses of thiacloprid the acute endpoint (larval mortality) is sufficient. In addition, new insights needed to develop a standardized test protocol were acquired, such as testing of a positive control for the first time and selection of male and female individuals at egg level.


Asunto(s)
Abejas/fisiología , Insecticidas/toxicidad , Neonicotinoides/toxicidad , Tiazinas/toxicidad , Animales , Femenino , Himenópteros , Larva/efectos de los fármacos , Estadios del Ciclo de Vida , Plaguicidas/toxicidad , Polen , Pruebas de Toxicidad
15.
Environ Sci Technol ; 55(8): 5248-5257, 2021 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-33719393

RESUMEN

CO2 capture and utilization provides an alternative pathway for low-carbon hydrocarbon production. Given the ample supply of high-purity CO2 emitted from ethanol and ammonia plants, this study conducted technoeconomic analysis and environmental life cycle analysis of several systems: integrated methanol-ethanol coproduction, integrated methanol-ammonia coproduction, and stand-alone methanol production systems, using CO2 feedstock from ethanol plants, ammonia plants, and general market CO2 supply. The cradle-to-grave greenhouse gas emissions of methanol produced from the stand-alone methanol, integrated methanol-ethanol, and integrated methanol-ammonia systems are 13.6, 37.9, and 84.6 g CO2-equiv/MJ, respectively, compared to 91.5 g CO2-equiv/MJ of conventional methanol produced from natural gas. The minimum fuel selling price (MFSP) of methanol ($0.61-0.64/kg) is 61-68% higher than the average market methanol price of $0.38/kg, when using a Department of Energy target renewable hydrogen production price of $2.0/kg. The methanol price increases to $1.24-1.28/kg when the hydrogen price is $5.0/kg. Without CO2 abatement credits, the H2 price needs to be within $0.77-0.95/kg for the MFSP of methanol to equal the average methanol market price. With a CO2 credit of $35/MT according to tax credit per metric ton of CO2 captured and used, the methanol price is reduced to $0.56-0.59/kg.


Asunto(s)
Efecto Invernadero , Hidrógeno , Animales , Dióxido de Carbono , Estadios del Ciclo de Vida , Metanol
16.
Environ Sci Technol ; 55(8): 5224-5235, 2021 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-33735568

RESUMEN

The transparent, flexible, and open-source Python library carculator_truck is introduced to perform the life cycle assessment of a series of medium- and heavy-duty trucks across different powertrain types, size classes, fuel pathways, and years in a European context. Unsurprisingly, greenhouse gas emissions per ton-km reduce as size and load factor increase. By 2040, battery and fuel cell electric trucks appear to be promising options to reduce greenhouse gas emissions per ton-km on long distance segments, even where the required range autonomy is high. This requires that various conditions are met, such as improvements at the energy storage level and a drastic reduction of the greenhouse gas intensity of the electricity used for battery charging and hydrogen production. Meanwhile, these options may be considered for urban and regional applications, where they have a competitive advantage thanks to their superior engine efficiency. Finally, these alternative options will have to compete against more mature combustion-based technologies which, despite lower drivetrain efficiencies, are expected to reduce their exhaust emissions via engine improvements, hybridization of their powertrain, as well as the use of biomass-based and synthetic fuels.


Asunto(s)
Gases de Efecto Invernadero , Emisiones de Vehículos , Animales , Electricidad , Gasolina/análisis , Estadios del Ciclo de Vida , Vehículos a Motor , Emisiones de Vehículos/análisis
17.
J Environ Manage ; 288: 112361, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33756385

RESUMEN

Ecologically designed wastewater treatment systems (ex., Eco-Machines™) utilize a diverse ecosystem to treat wastewater to the same extent as conventional treatment, but require less energy and chemical inputs. The environmental benefits of Eco-Machines™ can be theoretically maximized by incorporating hyperaccumulating aquatic plants (ex., duckweed) to facilitate nutrient recovery and conversion into protein-rich biomass, which can then be harvested for a range of agricultural and bioenergy applications. Although it has been established that ecological wastewater treatment systems are more cost- and energy-efficient than conventional wastewater treatment systems, a systematic life cycle assessment (LCA) of an Eco-Machine™ coupled with its beneficial by-products has not been conducted. In this study, a series of LCAs were performed on different operational scenarios for a 1000 gallon per day, pilot-scale Eco-Machine™ that, in addition to producing irrigation-quality water, also produces duckweed biomass for aquaculture. The analysis revealed that Eco-Machines™ located in warm climates, which do not require a greenhouse or supplemental heating, use approximately a third of the energy and produce half of the greenhouse gas emissions compared to conventional wastewater treatment systems in similar locations, while also providing benefits to human health, ecosystem quality, climate change, and resources. In addition, increasing the growth area for duckweed using vertical farming techniques improves the overall impact of the system. This study suggests that with proper management, ecological wastewater treatment systems that upcycle nutrients and water into beneficial products can provide a net benefit to human health and the environment.


Asunto(s)
Ganado , Purificación del Agua , Animales , Ecosistema , Humanos , Estadios del Ciclo de Vida , Aguas Residuales , Agua
18.
J Environ Manage ; 288: 112358, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33770726

RESUMEN

This study examines which management methods are the most recent and advanced in managing rejected brine generated from desalination plants. It also provides up-to-date information regarding the most adequate technologies that generate a minimum quantity of rejected brine via the use of minimization techniques and analyzes the method of direct disposal that has lately received noticeable improvements. It further discusses the reuse of discarded brine to recover valuable goods and sequestration of carbon dioxide. Sustainability is an important parameter that needs consideration to achieve uninterrupted operation of the discarded brine management to achieve the least environmental, social, and economic aftermath. To properly deal with any environmental issues related to brine disposal, different methods are implemented so that, in the end, higher water recovery is achievable from the desalination processes, namely brine minimization and rejection technologies (pressure retarded osmosis, microbial desalination cell technology), membrane-based technologies (vibratory shear enhanced processing, forward osmosis, electrodialysis, electrodialysis reverse, and electrodialysis metathesis, pervaporation method, thermal-based technologies (wind-aided intensified evaporation, brine concentrators, ohmic evaporator, membrane distillation, multi-stage flash distillation. This review also critically examined the two conventional approaches commonly used in life cycle assessment (LCA), when evaluating the ecotoxic effect of discarded brine. It intends to discuss the currently available methods and propose an improved method for evaluating the toxicity potential of brine on the aquatic ecosystem originated from seawater desalination plants. The Group-by-Group method takes into consideration the demerits of the two methods of the traditional method of LCA or chemical-specific approach as it provides a more holistic coverage for complicated brine to be disposed of. Recently, attention has been focused on recovering valuable metals from the discharged concentrated brine waste. Certainly, attaining marketable products from the discharged concentrated brine would offer an economic benefit and reducing the whole desalination costs. Ion imprinting polymers have potential applications in metal recovery from brine. Finding selective, more efficient, and less expensive imprinted polymers for extraction/pre-concentration of valuable ions is a vital and challenging task. Lastly, the brine should be seen as a resource and not as a waste to attain sustainability in its management approaches. Hybrid processes would be highly recommended to get the absolute transformation of the discarded brine from desalination processes to more valuable constituents.


Asunto(s)
Purificación del Agua , Animales , Ecosistema , Estadios del Ciclo de Vida , Ósmosis , Sales (Química) , Agua de Mar , Tecnología
19.
Glob Chang Biol ; 27(9): 1721-1736, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33657680

RESUMEN

The global demand for beef is rapidly increasing (FAO, 2019), raising concern about climate change impacts (Clark et al., 2020; Leip et al., 2015; Springmann et al., 2018). Beef and dairy contribute over 70% of livestock greenhouse gas emissions (GHG), which collectively contribute ~6.3 Gt CO2 -eq/year (Gerber et al., 2013; Herrero et al., 2016) and account for 14%-18% of human GHG emissions (Friedlingstein et al., 2019; Gerber et al., 2013). The utility of beef GHG mitigation strategies, such as land-based carbon (C) sequestration and increased production efficiency, are actively debated (Garnett et al., 2017). We compiled 292 local comparisons of "improved" versus "conventional" beef production systems across global regions, assessing net GHG emission data from Life Cycle Assessment (LCA) studies. Our results indicate that net beef GHG emissions could be reduced substantially via changes in management. Overall, a 46 % reduction in net GHG emissions per unit of beef was achieved at sites using carbon (C) sequestration management strategies on grazed lands, and an 8% reduction in net GHGs was achieved at sites using growth efficiency strategies. However, net-zero emissions were only achieved in 2% of studies. Among regions, studies from Brazil had the greatest improvement, with management strategies for C sequestration and efficiency reducing beef GHG emissions by 57%. In the United States, C sequestration strategies reduced beef GHG emissions by over 100% (net-zero emissions) in a few grazing systems, whereas efficiency strategies were not successful at reducing GHGs, possibly because of high baseline efficiency in the region. This meta-analysis offers insight into pathways to substantially reduce beef production's global GHG emissions. Nonetheless, even if these improved land-based and efficiency management strategies could be fully applied globally, the trajectory of growth in beef demand will likely more than offset GHG emissions reductions and lead to further warming unless there is also reduced beef consumption.


Asunto(s)
Efecto Invernadero , Gases de Efecto Invernadero , Animales , Brasil , Secuestro de Carbono , Bovinos , Humanos , Estadios del Ciclo de Vida
20.
Environ Sci Technol ; 55(6): 3888-3897, 2021 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-33661618

RESUMEN

Electrofuels from renewable H2 and waste CO2 streams are of increasing interest because of their CO2 emissions reduction potentials compared to fossil counterparts. This study evaluated the well-to-wheel (WTW) greenhouse gas (GHG) emissions of Fischer-Tropsch (FT) fuels from various electrolytic H2 pathways and CO2 sources, using various process designs (i.e., with and without H2 recycle) and system boundaries. Two systems with different boundaries were considered: a stand-alone plant (with CO2 from any source) and an integrated plant with corn ethanol production (supplying CO2). The FT fuel synthesis process was modeled using Aspen Plus, which showed that 45% of the carbon in CO2 can be fixed in the FT fuel, with a fuel production energy efficiency of 58%. Using nuclear or solar/wind electricity, the stand-alone FT fuel production from various plant designs can reduce WTW GHG emissions by 90-108%, relative to petroleum fuels. When integrating the FT fuel production process with corn ethanol production, the WTW GHG emissions of FT fuels are 57-65% lower compared to petroleum counterparts. This study highlights the sensitivity of the carbon intensity of FT fuels to the system boundary selection (i.e., stand-alone vs integrated), which has different implications under various GHG emission credit frameworks.


Asunto(s)
Efecto Invernadero , Zea mays , Animales , Dióxido de Carbono , Etanol , Hidrógeno , Estadios del Ciclo de Vida
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...