Fracture of Polyjet 3D printed materials: a preliminary investigation

Additive manufacturing (AM), in particular 3D printing, gained a lot of interest in the past few years. This work is focused in particular on the Polyjet 3D process by means of which photo-curable polymers with strongly different physical and mechanical properties can be injected (in the form of liquid droplets) and cured through the use of a UV lamp. In previous works [1,2] we already highlighted the important influence that the interphase between different constituents can have on the viscoelastic properties of the 3D printed composite materials. In view of extending our research beyond small deformations and towards the determination of the fracture properties of Polyjet composites, a preliminary investigation was carried out to characterize the fracture behaviour of base constituents, and to verify the applicability of conventional fracture mechanics approaches to this particular class of AM materials/structures. As a first step, the effect of several parameters on the apparent fracture properties was determined: material composition (rubber content), printing orientation, presence of support material and ageing time. For this study, two polymers were considered: VeroWhitePlus (RGD835) and VeroGray (RGD850). They both share the same glassy matrix, but VeroGray also includes a secondary rubbery phase. Tensile and scratch experiments were performed to evaluate bulk and surface mechanical properties, later to be considered as a basis to analyze fracture data obtained on three point bending notched samples, tested according to ISO 13586 to determine apparent toughness and fracture energy values, KIC and GIC. The applicability of a fracture mechanics framework to these materials was discussed

Integrated control of two tortricid (Lepidoptera) pests in apple orchards with sex pheromones and insecticides.

The apple is attacked by a significant number of insect pests in Brazilian commercial orchards, including Bonagota salubricola and Grapholita molesta (Lepidoptera: Tortricidae). Sexual disruption of B. salubricola and G. molesta was evaluated in apple orchard using the flowable pheromone formulations, SPLAT Grafo+Bona (SG+B), SPLAT Attract and Kill Grafo+Bona (SAKG+B), and compared with the standard insecticides used for management in the Integrated Apple Production (IAP) system. Both formulations were applied at a rate of 1kg/ha on October 10, 2005 and December 13, 2005 using 300 and 1000 point sources/ha of SG+B and SAKG+B, respectively in experimental units of 7 ha. Adult male captures of B. salubricola and G. molesta were evaluated weekly in Delta traps with specific synthetic sex pheromone from October 10, 2005 to February 14, 2006. Damage to fruits was evaluated on November 21 and December 21, 2005, and January 25 and February 14, 2006. In the SPLAT treated experimental units a significant reduction was observed in the number of B. salubricola and G. molesta males caught in Delta traps compared to the experimental unit IAP. Damage by B. salubricola at harvest ranged from 1.63 to 4.75% with no differences between treatments, while damage by G. molesta was near zero in all experimental units. Mating disruption using SG+B and SAKG+B was sufficient to control B. salubricola and G. molesta with results equivalent to IAP guidelines. This technology is promising for management of both pests in Brazilian apple orchards with immediate reduction of 43% in the number of insecticide applications

Acompanhamento da eficiência de atrativos alimentares para o monitoramento de Anastrepha fraterculus na cultura da ameixeira.

Neste trabalho, avaliou-se a eficiência de atrativos alimentares na captura de adultos de A. fraterculus em ameixeira no ano agrícola 2013/14 buscando melhorias no sistema de monitoramento dessa praga, uma vez que o atrativo padrão (suco de uva 25%) não tem sido eficiente em identificar sua presença nos pomares, dificultando a tomada de decisão de controle

Effect of food lures for monitoring of Anastrepha fraterculus (Diptera: Tephritidae) in Acca sellowiana (Myrtaceae).

The South American fruit fly, Anastrepha fraterculus (Diptera: Tephritidae) stands out for its polyphagous habit of damaging the production of several fruits in southern Brazil. This study aimed to evaluate the capture efficiency of A. fraterculus using grape juice at different periods of decomposition and aging as well as to test the capture efficiency of the enzymatic hydrolyzed protein Cera Trap® in feijoa crops. The work was conducted in a commercial feijoa orchard in São Joaquim, SC, Brazil during the 2014 growing season. Undiluted Cera Trap®, fresh grape juice and grape juice that had aged for 7 and 14 days were evaluated. All of the treatments with grape juice were used at the recommended concentration of 25 %. McPhail traps were used with 300 mL for each lure. On a weekly basis, the number of adults and the percentage of female fruit flies captured were evaluated, using identification and counting. Cera Trap® was the lure that captured the highest number of fruit flies, with a high percentage of females and with a higher frequency of captures during the season. Cera Trap® also showed the highest number of action thresholds compared to grape juice treatments. The 25 % fresh and aged grape juice showed a low number of captures and a low number of action thresholds. We conclude that fresh and aged grape juice were not effective for capturing and monitoring A. fraterculus in feijoa orchards. The Cera Trap® lure proves to be an alternative to improve monitoring of A. fraterculus in orchards in southern Brazil. Key words: Monitoring, fruit fly, control index, attractiveness, pest management. La mosca suramericana de las frutas Anastrepha fraterculus (Diptera: Tephritidae) se destaca por su hábito polífago, dañando la producción de diversas frutas en el sur de Brasil. El objetivo de este estudio fue evaluar la eficacia de la captura de moscas de la fruta utilizando jugo de uva en diferentes estados de descomposición y envejecimiento, así como evaluar la eficiencia de la captura de A. fraterculus con la proteína hidrolizada de origen animal Cera Trap® en un huerto de Acca sellowiana. El trabajo fue realizado en São Joaquim, SC, Brasil, durante la fructificación de 2014. Los tratamientos fueron: Cera Trap® sin diluir y jugo de uva fresco o envejecido durante 7 y 14 días. Los tratamientos con jugo de uva fueron utilizados a una concentración del 25 %. Se utilizaron trampas McPhail que contenían 300 mL de cada atrayente. Se evaluaron semanalmente el número de moscas adultas de las frutas y el porcentaje de hembras capturadas mediante el recuento e identificación de las especies. Cera Trap® fue el atrayente con el mayor número y mayor porcentaje de hembras de moscas capturadas, y de mayor frecuencia de capturas durante la estación proporcionando más posibilidades de control en comparación con los tratamientos que contenían jugo de uva. Se concluye que los jugos de uva fresca o envejecidos no fueron eficaces en la captura y monitoreo de A. fraterculus en huerto comercial de feijoa. El atrayente Cera Trap® demostró ser una alternativa para mejorar el monitoreo de A. fraterculus en huertos de feijoa. Palabras clave: Monitoreo, moscas de las frutas, instrucción de control, atracción, manejo de plagas

Feromônios sexuais no manejo de insetos-praga na fruticultura de clima temperado.

bitstream/item/95271/1/Feromonios-ULTIMA-VERSAO-08-07-2013.pdf; bitstream/item/95273/1/Capa-Feromonios.pd

Acompanhamento da eficiência de atrativos alimentares para o monitoramento de Anastrepha fraterculus (Diptera: Tephritidae) na cultura da macieira.

O objetivo do trabalho foi acompanhar a eficiência de atrativos alimentares para o monitoramento da espécie em pomar comercial em São Joaquim, SC no ano agrícola 2013/2014

Assessment of SPLAT formulations to control Grapholita molesta (Lepidoptera:Tortricidae) in a Brazilian apple orchard.

Mating disruption is a technique that uses synthetic copies of sex pheromones to control insect pests. We aimed to control Oriental fruit moth (OFM) Grapholita molesta (Busck) (Lepidoptera: Tortricidae) with formulations of SPLAT Grafo (SG) and SPLAT Grafo Attract and Kill (SGAK) in small (1 ha) apple (Malus domestica Borkh.) orchards. Our experiment was conducted in a commercial orchard with Gala trees (spacing 1.5 × 4.5 m) in Vacaria, Rio Grande do Sul State, Brazil. We evaluated the effect of four treatments on G. molesta population densities: a) SG at 1 kg ha-1 (300 point sources of 3.3 g each), b) SGAK at 1 kg ha-1 (1000 point sources of 1 g each), c) insecticides as recommended by Integrated Apple Production (IAP), and d) untreated control (no treatment). Specialized Pheromone and Lure Application Technology (SPLAT) treatments were applied on 1 August 2004 and reapplied after 120 d (1 December 2004). The treatment effect was evaluated by weekly counts of males captured in Delta traps baited with commercial synthetic sex pheromone lures (eight traps per treatment). We assessed fruit damage caused by G. molesta in eight replicates of 200 fruits each on 26 October, 30 November 2004, and 5 and 31 January 2005. Applying 1 kg ha-1 of SG and SGAK in August and December 2004 significantly reduced the number of male moths caught in Delta traps. Damage to fruits at harvest, however, did not differ significantly from the control. This indicates a decline in the efficacy of mating disruption when SG and SGAK are used to protect small areas (1 ha) under high Oriental fruit moth pressure

Diagnóstico dos serviços de polinização comercial em pomares de macieiras no Brasil.

The pollination services performed by Apis mellifera are essential for the high-quality apple production. The aim of this study was to obtain information about the pollination services used in the municipalities of Vacaria-RS e São Joaquim-SC, the main apple-producing regions in Brazil. Semi-structured interviews were conducted with apple growers and technicians responsible for the orchards during 2013 and 2015. The obtained information was: a) cropping systems; b) use of pollination services; c) number of hives per hectare during flowering; d) renting value of hives; e) mortality of colonies; f) agrochemicals used on flowering; g) presence of native bees on flowering. In Vacaria and São Joaquim, respectively, 70% and 68.6% of the apple growers use the integrated apple production as their production model. The directed pollination is used by 100% and 90.0% of respondents respectively, from which, 80% and 47.1% opt for the hive rent. On average, three hives were used per hectare in both regions. The average cost is U$17.52 and U$ 17.74 per hive, respectively. During the flowering period, insecticides and fungicides are used by 100% and 97.2% of the apple growers. The highest mean percentage of mortality of colonies during flowering was reported in Vacaria, 11.8%. Native bees are often found in apple flowers. The development of management strategies for the conservation of domestic and wild pollinators is essential. Os serviços de polinização realizados por Apis mellifera são fundamentais para a produção de maçãs com qualidade. O objetivo deste estudo foi obter informações sobre os serviços de polinização utilizados nos municípios Vacaria-RS e São Joaquim-SC, principais regiões produtoras de maçãs no Brasil. Entrevistas presenciais com questionários semiestruturados foram realizadas junto aos maleicultores e técnicos responsáveis pelos pomares, entre 2013 e 2015. As informações obtidas foram: a) sistema de cultivo adotado; b) emprego de serviços de polinização; c) número de colmeias por hectare na floração; d) valor do aluguel de colmeias; e) mortalidade de colônias; f) insumos químicos utilizados na floração; e g) presença de abelhas nativas na floração. Em Vacaria e São Joaquim, 70% e 68,6% dos maleicultores utilizam a produção integrada de maçã como modelo produtivo. A polinização comercial é utilizada por 100% e 90,0% dos entrevistados, respectivamente, dos quais 80% e 47,1% optam pelo aluguel de colmeias. Em média, são utilizadas três colmeias por hectare em ambas as regiões. O custo médio é de R$56,60 e R$ 57,30 por colmeia, respectivamente. Durante a floração, agrotóxicos foram utilizados por 100% e 97,2% dos entrevistados. O maior percentual médio de mortalidade de colônias foi relatado em Vacaria, 11,8%. Abelhas nativas são frequentemente observadas na floração. É imprescindível o desenvolvimento de estratégias de manejo para a conservação de polinizadores domésticos e silvestres. Termos para indexação Malus domestica; Apis mellifera; Diagnóstico da polinização; entrevista

Antimicrobial activity of resveratrol-derived monomers and dimers against foodborne pathogens

Plant polyphenolic compounds are considered a promising source for new antibacterial agents. In this study, we evaluated the antimicrobial activity of a collection of resveratrol-derived monomers and dimers screened as single molecules against a panel of nine foodborne pathogens. The results demonstrated that two monomers (i.e., pterostilbene 2 and (E)-3-hydroxy-4\u2032,5-dimethoxystilbene 9) and three dimers (i.e., \u3b4-viniferin 10, viniferifuran 14 and dehydro-\u3b4-viniferin 15) were endowed with significant antibacterial activity against gram-positive bacteria. The exposure of gram-positive foodborne pathogens to 100 \ub5g/mL of 2, 9 and 15 induced severe cell membrane damage, resulting in the disruption of the phospholipid bilayer. The most promising dimeric compound, dehydro-\u3b4-viniferin 15, was tested against Listeria monocytogenes, resulting in a loss of cultivability, viability and cell membrane potential. TEM analysis revealed grave morphological modifications on the cell membrane and leakage of intracellular content, confirming that the cell membrane was the principal biological target of the tested derivative

Structural requirements of benzofuran derivatives dehydro-δ-and dehydro-ε-viniferin for antimicrobial activity against the foodborne pathogen listeria monocytogenes

In a recent study, we investigated the antimicrobial activity of a collection of resveratrol-derived monomers and dimers against a series of foodborne pathogens. Out of the tested molecules, dehydro-\u3b4-viniferin and dehydro-\u3b5-viniferin emerged as the most promising derivatives. To define the structural elements essential to the antimicrobial activity against the foodborne pathogen L. monocytogenes Scott A as a model Gram-positive microorganism, the synthesis of a series of simplified benzofuran-containing derivatives was carried out. The systematic removal of the aromatic moieties of the parent molecules allowed a deeper insight into the most relevant structural features affecting the activity. While the overall structure of compound 1 could not be altered without a substantial loss of antimicrobial activity, the structural simplification of compound 2 (minimal inhibitory concentration (MIC) 16 \u3bc\ub5g/mL, minimal bactericidal concentration (MBC) >512 \u3bc\ub5g/mL) led to the analogue 7 with increased activity (MIC 8 \u3bc\ub5g/mL, MBC 64 \u3bc\ub5g/mL)