2,997 research outputs found
Kinetic Modeling of 1‐G Ethanol Fermentations
The most recent rise in demand for bioethanol, due mainly to economic and environmental issues, has required highly productive and efficient processes. In this sense, mathematical models play an important role in the design, optimization, and control of bioreactors for ethanol production. Such bioreactors are generally modeled by a set of first‐order ordinary differential equations, which are derived from mass and energy balances over bioreactors. Complementary equations have also been included to describe fermentation kinetics, based on Monod equation with additional terms accounting for inhibition effects linked to the substrate, products, and biomass. In this chapter, a reasonable number of unstructured kinetic models of 1‐G ethanol fermentations have been compiled and reviewed. Segregated models, as regards the physiological state of the biomass (cell viability), have also been reviewed, and it was found that some of the analyzed kinetic models are also applied to the modeling of second‐generation ethanol production processes
Electricity generation from biogas on swine farm considering the regulation of distributed energy generation in Brazil: a case study for Minas Gerais
The objective of this study was to analyze the feasibility of using agricultural waste from a swine farm to produce biogas, which can be used to generate electricity. For this purpose, the waste production potential was evaluated to determine the biogas production capacity of the farm. This measurement allowed scaling the size of the generator used to the electricity production to meet the needs of the farm as well as surplus electricity. The surplus electricity may be used on the farm when the generator is under maintenance or the electricity consumption is larger than the energy generated. This process is regulated by Normative Resolutions 482 and 687 in Brazil. The results of the analysis of the net present value, internal return rate, payback period and benefit cost ratio indicated that the project was feasible
Use of natural rubber membranes as support for powder TiO2 and Ag/TiO2 photocatalysts
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The purpose of this study was to synthesize TiO2-polymer composites able to act as photocatalyst membranes. TiO2 catalysts were prepared using the sol-gel method to contain 0.0, 0.5, 1.0, and 2.0 wt.% of embedded Ag particles, subsequently incorporated into natural rubber latex at a weight fraction of 15%. Samples of these ceramic powders were suspended in a latex emulsion (natural rubber), cast in Petri dishes and slowly dried in an oven. The resulting materials were evaluated by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, diffuse reflectance spectroscopy, differential scanning calorimetry, thermogravimetry, and photocatalytic assaying using methylene blue as an organic pollutant reference. All composite membranes exhibited good photoactivity conferred by TiO2 powder, with 98% dye fading after 300 min of ultraviolet irradiation.The purpose of this study was to synthesize TiO2-polymer composites able to act as photocatalyst membranes. TiO2 catalysts were prepared using the sol-gel method to contain 0.0, 0.5, 1.0, and 2.0 wt.% of embedded Ag particles, subsequently incorporated in273575583CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFUNDECT - FUNDAÇÃO DE APOIO AO DESENVOLVIMENTO DO ENSINO, CIÊNCIA E TECNOLOGIA DO ESTADO DE MATO GROSSO DO SUL |Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)sem informaçãosem informaçãosem informaçãosem informaçãoThe authors wish to thank the Brazilian funding agencies Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and Fundação de Apoio ao Desenvolvimento do Ensino, Ciênci
Automatic subject-based contextualisation of programming assignment lists.
As programming must be learned by doing, introductory
programming course learners need to solve many problems,
e.g., on systems such as ’Online Judges’. However, as such
courses are often compulsory for non-Computer Science (nonCS) undergraduates, this may cause difficulties to learners
that do not have the typical intrinsic motivation for programming as CS students do. In this sense, contextualised
assignment lists, with programming problems related to the
students’ major, could enhance engagement in the learning
process. Thus, students would solve programming problems
related to their academic context, improving their comprehension of the applicability and importance of programming.
Nonetheless, preparing these contextually personalised programming assignments for classes for different courses is really laborious and would increase considerably the instructors’/monitors’ workload. Thus, this work aims, for the first
time, to the best of our knowledge, to automatically classify the programming assignments in Online Judges based
on students’ academic contexts by proposing a new context
taxonomy, as well as a comprehensive pipeline evaluation
methodology of cutting edge competitive Natural Language
Processing (NLP). Our comprehensive methodology pipeline
allows for comparing state of the art data augmentation,
classifiers, beside NLP approaches. The context taxonomy
created contains 23 subject matters related to the non-CS
majors, representing thus a challenging multi-classification
problem. We show how even on this problem, our comprehensive pipeline evaluation methodology allows us to achieve
an accuracy of 95.2%, which makes it possible to automatically create contextually personalised program assignments
for non-CS with a minimal error rate (4.8%)
Current status of the whitefly Aleurodicus dispersus as an invasive pest in the CapeVerte Islands
In the last three decades, the spiralling whitefly (Aleurodicus dispersus) has become an important international pest. The movement of plants and parts of plants (such as fruits) in international trade and tourism, and by natural dispersal, has favoured its introduction to new areas. In common with others whiteflies of economic importance, the immature and adult stages cause direct feeding damage by piercing and sucking of sap from foliage, and
indirect damage following the accumulation all over host plants of honeydew and waxy flocculent material produced by the insects. Spiralling whitefly is a pest of tropical and subtropical crops, and highly polyphagous. Up to the 1970s, it had been recorded on 44 genera of plants, belonging to 26 botanical families (Mound & Halsey, 1978). This situation changed with the dispersal of the pest to new areas. Nowadays, the spiralling whitefly is one of the major pest of vegetable, ornamental and fruit crops around the globe
(Lambkin, 1999). Important host crops include: banana (Musa sapientum), Citrus spp., coconut (Cocos nocifera), eggplant (Solanum melanogena), guava (Psidium guajava), Hibiscus rosa sinensis, Indian almond (Terminalia catappa), papya (Carica papaya), Rosa
sp. and tomato (Lycopersicon esculentum) (Saminathan & Jayaraj, 2001). Spiralling whitefly has its origin in the tropical Americas, including Brazil. Although the pest has been recorded only once in Brasil, in the 1920s in the state of Bahia (Bondar, 1923), it now
has official quarantine status because of its economic importance. In the Cape Verte Islands, on the West African coast, the pest was initially introduced in the first half of 2000;
it has since become established, reaching urban, natural and agricultural areas of the islands that constitute the archipelago. Since then, the pest has been causing damage to many
native plants, ornamentals and cultivated food crops (Anon., 2001; Monteiro, 2004). The present study was done in order to produce an inventory of the most common host plants of
spiralling whitefly in this new habitat
Correlação entre o conteúdo inorgânico e a polimerização da matriz orgânica das resinas compostas para restaurações dentárias: uma revisão narrativa
Introduction: In recent years, resin-matrix composite materials have revealed a fast technological improvement for dental applications. However, there are still some drawbacks related to the chemical composition, polymerization, and mechanical properties of resin-matrix composites with consequences in long-term clinical success. Objective: This study aimed to perform a narrative review regarding the effects of inorganic fillers on the organic matrix polymerization of resin-matrix composites. Materials and Methods: A search was performed in PubMed using relevant related key terms related to the chemical composition, properties and polymerization of resin matrix composites. Relevant studies published between 2001 and 2021 were selected. Results: The studies included in the present research provided relevant information on the chemical composition and properties of resin composites and polymerization factors, including the time, wavelength mode, and equipment. Studies have reported that silica and silicate nano-scale particles improve light transmission through resin-matrix composites and the degree of conversion of monomers in the organic matrix. Micrometric particles with a high refractive index can decrease the degree of conversion of monomers in the organic matrix. Conclusion: The polymerization of resin-matrix composites is affected by light scattering due to the type of inorganic particles and the differences in refractive indexes of inorganic and organic contents.Introdução: Nos últimos anos, as resinas compostas têm sido melhoradas em termos tecnológicos, permitindo o
alcance de melhores prognósticos na medicina dentária. Entretanto, subsistem algumas limitações relacionadas com
a composição química e as propriedades das resinas compostas com consequências no sucesso clínico a longo prazo.
Objetivo: O objetivo deste trabalho foi realizar uma revisão narrativa sobre a influência da componente inorgânica na
polimerização da matriz orgânica das resinas compostas usadas para restauração dentária. Materiais e Métodos: A
pesquisa foi realizada na plataforma PubMed utilizando termos de pesquisa relacionados com a composição química,
propriedades e a polimerização das resinas compostas, para seleção de artigos relevantes ao tema. Resultados:
Os estudos identificados reportam diferentes fatores relacionados com a polimerização incluindo modo, tempo,
equipamento e a composição química das resinas compostas. Os estudos indicam que partículas nanométricas à
base de sílica ou silicatos promovem uma maior transmissão de luz à matriz orgânica o que favorece a polimerização
do material. Por outro lado, partículas micrométricas com um alto índice de refração podem diminuir o grau de
conversão dos monómeros da matriz orgânica. Conclusão: A polimerização das resinas compostas é afetada pela
dispersão da luz, devido ao tamanho das partículas inorgânicas e aos índices de refração da componente orgânica e
inorgânica. De fato, um maior controlo da composição química e do tamanho de partículas inorgânicas aumenta o
grau de polimerização das resinas compostas
Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry
Objectives
The aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content.
Methods
Resin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation’s tests, while Vicker’s hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey’s test (p < 0.05).
Results
After polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78–80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content.
Conclusions
A high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites.
Clinical significance
The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation.Open access funding provided by FCT|FCCN (b-on). This work was supported by FCT (Portugal) in the subject of the following project: PTDC/EMEEME/4197/2021; by CAPES regarding the following projects: CAPES-PRINT/88881.310728/2018–01; and CAPESHUMBOLDT Program (grant number 88881.197684/2018–01). S.C. thanks FCT for her contract funding provided through 2020.00215. CEECIND
Impact of pulmonary rehabilitation on the social support of people with COPD
Social support improves general health (e.g., reduces hospitalisations and exacerbations) and well-being of people with COPD, but it has shown to be low in this population. Pulmonary rehabilitation (PR) has potential to improve social support of people with COPD, however, this needs to be investigated. This study explored the impacts of PR on the social support of people with COPD.
An observational study was conducted. Participants received community-based PR for 3 months, twice a week. Sociodemographic and lung function data were used to characterise the sample. Quantity and quality of social support were assessed with the 6-item short form Social Support Questionnaire (SSQ). For each item, participants listed all people or institutions who support them on a certain situation (range: 0-9 people; quantity) and indicated how satisfied they were with the support provided (range: 1 very dissatisfied to 6 very satisfied; quality). Total score for quantity and quality was computed using the mean scores from the 6 items.
Frequencies, median and interquartile range (IQR) were used to describe the sample. Wilcoxon test was used to explore pre-post differences.
Twenty-nine people with COPD (71 [65-77] years; 86.2% ♂; 54 [39.4-62.5] FEV1%pp) participated. No significant impacts were found for quantity (pre 1.5 [1-3.2] vs post 1.7 [1-2.2], p=0.135) nor quality (pre 6 [5.7-6] vs post 6 [5.4-6], p=0.299) of social support after PR. A ceiling effect seem to exist on quality.
PR seems to yield minimal impact on the social support of people with COPD assessed with the SSQ. Future work on how to improve social support of people with COPD is needed (e.g., identify determinants and social responses).publishe
Glycemic index and glycemic response of corn starch porridge with addition of oats, flaxseed or soluble fiber isolated
Indexación: ScopusIntroduction: Fibers are commonly known to contribute in the improvement of glycemic and lipid profile, exerting a beneficial effect on health, but its effect on the glycemic index of food is still controversial. Objective: To evaluate the effect of adding high-fiber foods (oats and flaxseed) and a supplement of soluble fiber isolated on the glycemic index (GI) and glycemic response of a porridge of corn starch. Methodology: The study was of crossover, where six healthy subjects ingested preparations based on a maize porridge added to different foods rich in fiber, the GI of the preparations was calculated according to the methodology of FAO. Results: The preparation of linseed added resulting in a lesser glycemic response times 45-90 min and with the addition of oat preparation showed the best results at times 60 and 90 minutes. The mean area under the curve of the glycemic response and GI of the preparations did not differ. Conclusion: Oatmeal linseed seem foods with beneficial properties reduce the glycemic response to food.http://revista.nutricion.org/revista.asp?id=4
Multifunctional silver-coated transparent TiO2 thin films for photocatalytic and antimicrobial applications
Transparent TiO2 thin films coated with Ag NPs were synthesized using two industrially applicable techniques,
pulsed laser ablation (PLAL) and spray pyrolysis without using high vacuum. These transparent thin films were
deposited on glass in order to generate glass materials with photocatalytic and antimicrobial properties and a
minimum loss of transparency. The structural, morphological and optical properties of the thin films were
examined using Grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, Scanning electron microscopy (SEM) and ultraviolet–visible spectroscopy. Transmission electron microscopy (TEM) was used to identify
the NPs on the TiO2 surface. The transmittance value for the thin films was greater than 80%.The thin films thus
synthesized were then assessed to determine their photocatalytic capacity by monitoring the degradation of
Rhodamine B (RhB) under UV light irradiation. Ag NPs on the TiO2 surface ensures an improvement in the
photocatalytic properties, with a 99% degradation of RhB in 210 min under UV light. In addition, these transparent thin films showed high antimicrobial activity on Gram-negative bacteria when irradiated by UV light for
4 h, killing 93% of these bacteria.Funding for open access charge: CRUE-Universitat Jaume
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