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 $12$ 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

Biodegradable wet-spun fibers modified with antimicrobial agents for potential applications in biomedical engineering

Wet-spinning is a non-solvent induced phase inversion technique that allows the production of continuous polymeric microfibers, with a uniform morphology, based on the principle of precipitation. It allows the production of 3D fibrous constructs with an intricated architecture that facilitates cell infiltration, something that is very limited in electrospun nanofibrous mats, thus increasing its interest in biomedicine. Wet-spun scaffolds are also more easily processed and can be loaded with a variety of biomolecules of interest. Antimicrobial agents that display a broad spectrum of activity against bacteria, fungi and viruses have been combined with such constructs demonstrating great potential to fight infections. In the present work, we explore the use of wet-spinning to process both natural and synthetic biodegradable polymers in the form of microfibers, and the necessary processes to modify their surface to increase their antimicrobial profile. The synergistic potential of specialized biomolecules within wet-spun fibrous architectures are also highlighted.Authors acknowledge the Foundation for Science and Technology (FCT) of Portugal for funding the projects PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074) and UID/CTM/00264/2020 from 2C2T

Combinatory action of chitosan-based blended films and loaded cajeput oil against Staphylococcus aureus and Pseudomonas aeruginosa-mediated infections

Chronic wounds (CW) have numerous entry ways for pathogen invasion and prosperity, damaging host tissue and hindering tissue remodeling. Essential oils exert quick and efficient antimicrobial (AM) action, unlikely to induce bacterial resistance. Cajeput oil (CJO) has strong AM properties, namely against Staphylococcus aureus and Pseudomonas aeruginosa. Chitosan (CS) is a natural and biodegradable cationic polysaccharide, also widely known for its AM features. CS and poly(vinyl alcohol) (PVA) films were prepared (ratio 30/70; 9 wt%) by solvent casting and phase inversion method. Films’ thermal stability and chemical composition data reinforce polymer blending. Films were supplemented with 1 and 10 wt% of CJO in relation to total polymeric mass. Loaded films were 23 and 57% thicker, respectively, than the unloaded films. Degree of swelling and porosity also increased, particularly with 10 wt% CJO. AM testing revealed that CS films alone were effective against both bacteria, eradicating all P. aeruginosa within the hour (*** p < 0.001). Still, loaded CS/PVA films showed improved AM traits, being significantly more efficient than unloaded films right after 2 h of contact. This study is the first proof of concept that CJO can be dispersed into CS/PVA films and show bactericidal effects, particularly against P. aeruginosa, this way opening new avenues for CW therapeutics.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTMTEX/28074/2017 (POCI-01-0145-FEDER-028074). Authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTES

Sodium alginate/polycaprolactone co-axial wet-spun microfibers modified with N-carboxymethyl chitosan and the peptide AAPV for Staphylococcus aureus and human neutrophil elastase inhibition in potential chronic wound scenarios

In chronic wound (CW) scenarios, Staphylococcus aureus-induced infections are very prevalent. This leads to abnormal inflammatory processes, in which proteolytic enzymes, such as human neutrophil elastase (HNE), become highly expressed. Alanine-Alanine-Proline-Valine (AAPV) is an antimicrobial tetrapeptide capable of suppressing the HNE activity, restoring its expression to standard rates. Here, we proposed the incorporation of the peptide AAPV within an innovative co-axial drug delivery system, in which the peptide liberation was controlled by N-carboxymethyl chitosan (NCMC) solubilization, a pH-sensitive antimicrobial polymer effective against Staphylococcus aureus. The microfibers' core was composed of polycaprolactone (PCL), a mechanically resilient polymer, and AAPV, while the shell was made of the highly hydrated and absorbent sodium alginate (SA) and NCMC, responsive to neutral-basic pH (characteristic of CW). NCMC was loaded at twice its minimum bactericidal concentration (6.144 mg/mL) against S. aureus, while AAPV was loaded at its maximum inhibitory concentration against HNE (50 μg/mL), and the production of fibers with a core-shell structure, in which all components could be detected (directly or indirectly), was confirmed. Core-shell fibers were characterized as flexible and mechanically resilient, and structurally stable after 28-days of immersion in physiological-like environments. Time-kill kinetics evaluations revealed the effective action of NCMC against S. aureus, while elastase inhibitory activity examinations proved the ability of AAPV to reduce HNE levels. Cell biology testing confirmed the safety of the engineered fiber system for human tissue contact, with fibroblast-like cells and human keratinocytes maintaining their morphology while in contact with the produced fibers. Data confirmed the engineered drug delivery platform as potentially effective for applications in CW care.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTMTEX/28074/2017 (POCI-01-0145-FEDER-028074). Authors also acknowledge project UIDP/00264/2020 of 2C2T and UID/QUI/00686/2020 of CQ, funded by national funds through FCT/MCTES. C.S.M. and H.P.F. also acknowledge FCT for PhD funding via scholarship 2020.08547.BD and for auxiliary researcher contract via 2021.02720.CEEIND, respectively

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

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

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

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