90 research outputs found
Formation energy and interaction of point defects in two-dimensional colloidal crystals
The manipulation of individual colloidal particles using optical tweezers has
allowed vacancies to be created in two-dimensional (2d) colloidal crystals,
with unprecedented possibility of real-time monitoring the dynamics of such
defects (Nature {\bf 413}, 147 (2001)). In this Letter, we employ molecular
dynamics (MD) simulations to calculate the formation energy of single defects
and the binding energy between pairs of defects in a 2d colloidal crystal. In
the light of our results, experimental observations of vacancies could be
explained and then compared to simulation results for the interstitial defects.
We see a remarkable similarity between our results for a 2d colloidal crystal
and the 2d Wigner crystal (Phys. Rev. Lett. {\bf 86}, 492 (2001)). The results
show that the formation energy to create a single interstitial is
lower than that of the vacancy. Because the pair binding energies of the
defects are strongly attractive for short distances, the ground state should
correspond to bound pairs with the interstitial bound pairs being the most
probable.Comment: 5 pages, 2 figure
Tomato seedling production in substrate containing coconut fiber and mushroom culture waste AB S TR ACT
Tomato seedling production in substrate containing coconut fiber and mushroom culture waste Revista Brasileira de Ciências Agrárias, vol. 3, núm. 3, julio-septiembre, 2008, pp. 237-241 Universidade Federal Rural de Pernambuco Pernambuco, Brasil Tomato seedling production in substrate containing coconut fiber and mushroom culture waste AB S TR ACT The objective of this research was to evaluate the ratio of coconut fiber and mushroom culture waste in the tomato seedling production. A greenhouse experiment was carried out in the randomized block experimental design, with seven treatments and four replications: T1 -Commercial Substrate Hortimix®; T2 -0% coconut fiber dry matter (CF) + 100% dry matter of mushroom culture waste (MW); T3 -20% (CF) + 80% (MW); T4 -40% (CF) + 60% (MW); T5 -60% (CF) + 40% (MW); T6 -80% (CF) + 20% (MW); T7 -100% (CF) + 0% (MW). Stem diameter, seedling height, emergence speed, germination percentage, shoot and root fresh matter and shoot and root dry matter were evaluated. It was evidenced, for all the studied characteristics, with exception of the speed of germination-aid seedling emergence and of the germination percentage, significant differences between substrate containing coconut fiber and mushroom culture residue and the commercial substratum, the best results presented by the last one. The increase in the proportion of mushroom residue in relation to the coconut fiber provided tomato seedling with better characteristics than the others. Key words: organic substrate, recycling, organic manure, germination Produção de mudas de tomate em substrato contendo fibra de coco e resíduo de cultivo de cogumelo RES UMO Visou-se, com o presente trabalho, avaliar proporções de fibra de coco e de resíduo proveniente do cultivo de cogumelo como substratos para a produção de mudas de tomate. O experimento foi conduzido em casa de vegetação, tendo-se utilizado o delineamento em blocos inteiramente casualizados, com sete tratamentos e quatro repetições: T 1 -Substrato comercial Hortimix ® ; T 2 -0% matéria seca de fibra de coco (FC) + 100% matéria seca de resíduo proveniente do cultivo de cogumelo (RC); T 3 -20% FC + 80% RC; T 4 -40% FC + 60% RC; T 5 -60% + 40% RC; T 6 -80% FC + 20% RC; T 7 -100% FC + 0% RC. Avaliaram-se o diâmetro do caule, a altura da planta, o índice de velocidade de emergência, a percentagem de germinação, a matéria fresca da parte aérea e da raiz, e a matéria seca da parte aérea e da raiz. Constataram-se, para todas as características estudadas, com exceção do índice de velocidade emergência e da percentagem de germinação, diferenças significativas entre os substratos contendo fibra de coco e resíduo do cultivo de cogumelo e o substrato comercial, em que este último apresentou os melhores resultados. O aumento da proporção de resíduo de cogumelo em relação à fibra de coco proporcionou a produção de mudas com melhores características que as demais
A linguagem literária do New Journalism em The Duke in His Domain
O presente artigo possui o intuito de esclarecer como a linguagem literária foi atrelada à linguagem jornalística na categoria New Journalism (Novo Jornalismo, no português). Para isso, utilizamos trechos do artigo The Duke in His Domain, de Truman Capote, que se trata de um perfil-reportagem do ator hollywoodiano Marlon Brando, escrito em 1957 e publicado na famosa revista nova-iorquina, The New Yorker. A relevância para análise deste objeto de pesquisa não é somente em relação ao toque literário, mas também devido a sua importância histórica e jornalística, pois é sabido que tal texto é um precursor do New Journalism. O referencial teórico da pesquisa é embasado em um artigo de Cyntia Belgini Andretta, estudiosa da obra de Truman Capote, e em autores que se dedicam ao estudo do jornalismo-literário, como Eduardo Belo e Marcelo Bulhões. Com o resultado da pesquisa, a análise de trechos do artigo de Capote ajudará a esclarecer dúvidas em relação ao uso dos recursos literários dentro do jornalismo
Reducing the effects of Low Albedo of asphalt materials incorporating Polyethylene Glycol (PEG) 1000, 2000 and 4000 as Phase Change Materials (PCM)
Albedo plays a vital role in urban microclimates. Civil engineering structures usually absorb a high amount of energy in form of heat, for example asphalt pavements, which have a low albedo, thus contributing to the Urban Heat Island (UHI) effects. Modifying the physical characteristics of asphalt pavements, including reflectance and thermal properties, can help mitigate UHI. The literature points out that one alternative to thermoregulating asphalt materials is the incorporation of phase change materials. Thus, the main goal of this research is to present a systematic review regarding the effectiveness of the incorporation of polyethylene glycol (PEG) 1000, 2000 and 4000 as Phase Change Material (PCM) in asphalt materials. The results showed that incorporating PEG into asphalt materials can regulate heat storage, promoting stability and reducing UHI effects. PEG2000 was more frequently used. PEGs can reduce between of 3.5 and 4.2ºC of the asphalt materials when compared to the conventional ones.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of
the Strategic Funding UIDB/04650/2020 and the projectsMicroCoolPav project EXPL/EQU-EQU/1110/2021, and
NanoAir project PTDC/FISMAC/6606/2020
Bioeconomic efficiency of lamb finishing production systems.
Abstract: This study aimed to evaluate the production performance, quantitative carcass characteristics, and economic viability of lambs of genetic group Pantaneiro finished under four production systems: 1) Stockpiled Brachiaria brizantha cv piatã pasture; 2) Consortium of sorghum intercropped with Brachiaria brizantha cv piatã; 3) Feedlot based on sorghum silage and 2% body weight energyprotein supplementation, 4) Feedlot based on sorghum silage and 4% body weight energy-protein supplementation. Were used one hundred Pantaneiro lambs with an average body weight of 17.85 ± 2.50 kg and at 70 ± 15 days of age, approximately. The average final body weight and total body weight gain of the animals finished on the consortium of sorghum intercropped with Brachiaria brizantha cv piatã were higher than those obtained with feedlot based on sorghum silage and 2% body weight energy-protein supplementation. However, when this system were compared with sorghum silage and 4% body weight energy-protein supplementation, these characteristics did not differ (P > 0.05). Hot and cold carcass weights were lower when animals were fed sorghum silage and 2% body weight energyprotein supplementation as compared with the animals finished on the other systems. The greatest hot (48.20%) and cold (45.83%) carcass yields were observed in animals finished on sorghum silage and 4% body weight energy-protein supplementation. For the carcass compactness index, animals that received sorghum silage and 4% body weight energy-protein supplementation obtained higher values than those observed for 2% of supplementation. The economic evaluation showed a great return for the finishing systems, except for sorghum silage and 4% body weight energy-protein supplementation, and concluded that finishing lambs in a crop-livestock integration system presented a higher benefit/cost ratio (1.61). Therefore, based on the conditions under which this study was conducted, the croplivestock integration is the most viable system for finishing lambs. [Eficiência bioeconômica de sistemas de terminação de cordeiros]. Resumo: Avaliou-se o desempenho produtivo, características quantitativas das carcaças e viabilidade econômica de cordeiros do grupamento genético Pantaneiro, terminados em quatro sistemas de produção: 1) Pastagem vedada de Brachiaria brizantha cv piatã; 2) Pastagem de Brachiaria brizantha cv piatã em plantio consorciado com sorgo; 3) Confinamento a base de silagem de sorgo e suplementação energéticoproteica fornecida na proporção de 2% do peso corporal; 4) Confinamento a base de silagem de sorgo e suplementação energético-proteica fornecida na proporção de 4% do peso corporal. Foram utilizados cem cordeiros Pantaneiros com peso médio de 17,85 ± 2,50 kg e 70 ± 15 dias de idade, aproximadamente. O peso corporal médio final e o ganho de peso corporal total dos animais terminados em consórcio de sorgo com Brachiaria brizantha cv piatã foram superiores aos obtidos com o confinamento a base de silagem de sorgo e suplementação energético-proteica na razão de 2% do peso corporal. No entanto, quando comparados com o confinamento a base de silagem de sorgo e suplementação energético-proteica na razão de 4% do peso corporal, essas características não diferiram (P > 0,05). Os pesos de carcaça quente e fria foram inferiores para os animais alimentados com silagem de sorgo e suplementação energética-proteica na razão de 2% do peso corporal em comparação com os animais terminados nos outros sistemas. Os maiores rendimentos de carcaça quente (48,20%) e fria (45,83%) foram observados nos animais terminados com silagem de sorgo e suplementação energético-proteica na razão de 4% do peso corporal. Para o índice de compacidade da carcaça, os animais que receberam silagem de sorgo e 4% de suplementação energético-proteica com relação ao peso corporal obtiveram valores maiores do que os observados com 2% de suplementação. A avaliação econômica mostrou que houve um ótimo retorno econômico para os sistemas de terminação, exceto para o sistema de terminação com pasto vedado, e concluiu que a terminação de cordeiros em integração lavoura pecuária relação de benefício/custo superior (1,61). Portanto, baseado nas condições em que foi conduzido o estudo, a integração lavoura pecuária apresenta-se como o sistema mais viável para terminação de cordeiros
Coaxial fibres incorporated with phase change materials for thermoregulation applications
Nowadays, the growing concern about improving thermal comfort in different structures (textiles, buildings, and pavements, among others) has stimulated research into phase change materials (PCMs). The direct incorporation of PCMs into composite materials can cause mechanical impacts. Therefore, this study focuses on the design of phase change coaxial fibres (PCFs), using commercial cellulose acetate (CA) or recycled CA obtained from cotton fabrics (CAt) as the sheath and polyethylene glycol (PEG) 2000 as the core, via the wet spinning method; the fibres vary in molecular weight, concentration and ejection velocity. The fibres were assessed for their optical, chemical, thermal, and mechanical properties. The presence of PEG2000 is confirmed in the core of the fibres. Thermal analyses revealed a mass loss at high temperatures, attributable to the presence of PEG2000. Notably, the fibres with CA (Mn 30,000) showed superior thermal and mechanical performance. The melting point of PEG2000 incorporated into these PCFs coincided with the melting point of pure PEG2000 (about 55 °C), with a slight deviation, indicating that PCFs were obtained. Finally, the results point to the application of the fibres in civil engineering materials requiring a phase change between 50 and 60 °C, providing promising prospects for their use in applications requiring thermoregulatory properties.This research was funded by the Portuguese Foundation for Science and Technology (FCT) under the projects MicroCoolPav EXPL/EQUEQU/1110/2021 and NanoAir PTDC/FISMAC/6606/2020 (https://doi.org/10.54499/PTDC/FIS-MAC/6606/2020) and within the framework of Strategic Funding UIDB/04650/2020, UIDB/04029/2020 (https://doi.org/10.54499/UIDB/04029/2020) and UID/QUI/0686/2020. I.R.S. and H.P.F. would like to thank FCT for their funding contracts 2022.00763.CEECIND (https://doi.org/10.54499/2022.00763.CEECIND/CP1718/CT0006) and 2021.02720.CEECIND (https://doi.org/10.54499/DL57/2016/CP1377/CT0098)
Advancements in phase change materials in asphalt pavements for mitigation of urban heat island effect: bibliometric analysis and systematic review
This research presents a dual-pronged bibliometric and systematic review of the
integration of phase change materials (PCMs) in asphalt pavements to counteract the urban heat
island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt
research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably,
Chang’an University in China has emerged as a leading contributor. The systematic review
addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM
leakage prevention in asphalt, and effects on mechanical properties. The findings identify
polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCMs due to their
wide phase-change temperature range and significant enthalpy during phase transitions. While
including PCMs can modify asphalt’s mechanical attributes, such mixtures typically stay within
performance norms. This review emphasises the potential of PCMs in urban heat management and
the need for further research to achieve optimal thermal and mechanical balanceThis research was partially funded by the Portuguese Foundation for Science and
Technology (FCT) under the framework of the projects MicroCoolPav EXPL/EQU-EQU/1110/2021,
NanoAir PTDC/FIS-MAC/6606/2020, UIDB/04650/2020, and UIDB/04029/2020. This research was
also supported by the doctoral Grant PRT/BD/154269/2022 financed by the FCT, and with funds
from POR Norte-Portugal 2020 and State Budget, under MIT Portugal Program. I.R.S. would like to
acknowledge the FCT for funding (2022.00763.CEECIND). V.C.B. acknowledges the Fundação
Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (Funcap), MLC-0191-
00144.01.00/22 (Edital Mulheres na Ciência), and the National Council for Scientific and
Technological Development (CNPq), Process 404978/2021-5—Call CNPq/MCTI/FNDCT N°
18/2021—Faixa B—Consolidated Groups
Gas exchange, chemical composition and productive characteristics of tropical grasses deferred II: cultivars BRS Paiaguás and BRS Piatã.
Abstract: This study aimed to evaluate the physiological parameters, the productive characteristics, structural and chemical composition of Urochloa Brizantha cultivars BRS and BRS Piatã submitted to two deferment periods and three using times. The experimental design was randomized complete block design in a factorial scheme 2 x 2 x 3, being two grass cultivars (Paiaguás grass and Piatã grass), two deferment periods (rainy season and dryrainy transition) and three sealing times (40, 80 and 120 days). It was observed that, in the rainy season, the grasses had higher leaf transpiration rate when used for 40 days of deferment (1.66 ?mol m2/s). During the rainy season, the Stomatal conductance was detected only in the grasses used with shorter seal, with an average of 0.07 ?mol m2/s. In contrast, in the period of transition, the concentration decreased to 0.02 ?mol m2/s. In a general way, the BRS Paiaguás presented lower content of NDF. The shorter cycle provided greater biomass production of total forage during the period of rain, approximately 2.78 times more than the same pasture grass deferred during the transition period. Generally, the periods of deferment and moments of use cause effects on structural characteristics of pasture, being that the period of deferment of the transition period and used for 40 and 80 days may be a strategy for keeping animals in critical periods. [Trocas gasosas, características produtivas e composição química de gramíneas tropicais diferidas II: cultivares BRS Paiaguás e BRS Piatã]. Resumo: Objetivou-se avaliar os parâmetros fisiológicos, as características produtivas, estruturais e composição química da Urochloa Brizantha cultivares BRS Paiaguás e BRS Piatã submetidos a dois períodos de diferimento e três momentos de utilização. Utilizou-se o delineamento de blocos completos casualizados, em esquema fatorial 2 x 2 x 3, sendo duas cultivares de gramíneas (capim-paiaguás e capim- piatã), dois períodos de diferimento (período chuvoso e transição chuvoso-seco) e três tempos de vedação (40, 80 e 120 dias). Observou-se que, dentro do período chuvoso, as gramíneas tiveram maior taxa de transpiração foliar quando utilizadas aos 40 dias de diferimento (1,66 ?mol m2/s). Neste mesmo período, a condutância estomática foi detectada somente nas gramíneas utilizadas com menor tempo de vedação, apresentando média de 0,07 ?mol m2/s. Em contrapartida, no período de transição, a concentração diminuiu para 0,02 ?mol m2/s. De forma geral, a cultivar BRS Paiaguás apresentou menor teor de FDN. O menor tempo de vedação proporcionou maior produção de biomassa de forragem total durante o período da chuva, cerca de 2,78 vezes mais forragem que o mesmo pasto diferido durante o período de transição. De modo geral, ambos os períodos de diferimento e tempos de vedação causam efeitos nas características estruturais da pastagem, sendo que o diferimento no período de transição por um tempo de 40 e 80 dias pode ser uma estratégia para manutenção dos animais em períodos críticos
Performance Analysis of YOLO and Detectron2 Models for Detecting Corn and Soybean Pests Employing Customized Dataset
One of the most challenging aspects of agricultural pest control is accurate detection of insects in crops. Inadequate control measures for insect pests can seriously impact the production of corn and soybean plantations. In recent years, artificial intelligence (AI) algorithms have been extensively used for detecting insect pests in the field. In this line of research, this paper introduces a method to detect four key insect species that are predominant in Brazilian agriculture. Our model relies on computer vision techniques, including You Only Look Once (YOLO) and Detectron2, and adapts them to lightweight formats—TensorFlow Lite (TFLite) and Open Neural Network Exchange (ONNX)—for resource-constrained devices. Our method leverages two datasets: a comprehensive one and a smaller sample for comparison purposes. With this setup, the authors aimed at using these two datasets to evaluate the performance of the computer vision models and subsequently convert the best-performing models into TFLite and ONNX formats, facilitating their deployment on edge devices. The results are promising. Even in the worst-case scenario, where the ONNX model with the reduced dataset was compared to the YOLOv9-gelan model with the full dataset, the precision reached 87.3%, and the accuracy achieved was 95.0%
Alimentação popular em São Paulo (1920 a 1950): políticas públicas, discursos técnicos e práticas profissionais
This article discusses how the concept of lower-class eating habits came about and developed in the intellectual circles of São Paulo during the first half of the 20th century. It starts by reconstructing the elements of the debate around the income and ignorance of the underprivileged as the main reasons behind their bad eating habits. Then, it looks at the focal points for interventions and public policies proposed by the government to deal with the problem thus identified, namely: training methods to produce sanitation counselors capable of offering dietary guidance as well; popular educational campaigns and new learning sites in addition to schools (e.g. healthcare centers and households); lunch and other means of offering food at schools; and diagnostic studies about food intake and eating habits among laborers. Because they were translated into technical and scientific language, the proposals and policies implemented in São Paulo left traces in a variety of supporting documents and media (photographs, primers, posters, inquiry notebooks, and academic literature).O artigo discute a construção da idéia de alimentação popular nos meios intelectuais em São Paulo, na primeira metade do século XX. Para isso, reconstitui, como motivos da má alimentação, elementos do debate em torno da renda e da ignorância dos mais pobres. Identificado o problema, as propostas de intervenção e as políticas públicas concentraram-se em alguns setores, abordados neste trabalho: métodos para a formação de educadores sanitários aptos a atuar também na educação alimentar; campanhas de instrução popular e criação de novos lugares de aprendizado (além das escolas, os centros de saúde e os lares); merenda escolar e outras alternativas de alimentação nas escolas; e diagnósticos referentes ao conteúdo e à forma da alimentação dos operários. Traduzidas em discurso técnico-científicos, as propostas e políticas implementadas na cidade deixaram indícios em documentação de suporte e tipologia variados (fotografias, cartilhas, cartazes, cadernetas de inquéritos e textos acadêmicos).Universidade Federal de São Paulo (UNIFESP)UNIFESPSciEL
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