Bio-based synthesis of oxidation resistant copper nanowires using an aqueous plant extract

Copper nanowires have recently emerged as promising nanomaterials for transparent conducting electrodes applications, however, their production commonly involves the use of harmful reagents. In this study, we describe for the first time a simple and cost-effective bio-based synthesis of copper nanowires using an aqueous plant extract (Eucalyptus globulus) as the reducing/stabilizing agent and oleic acid and oleylamine as surfactants. Well-dispersed crystalline copper nanowires (λmáx = 584–613 nm) were obtained with average diameters in the nanometric range (44 and 145 nm) and lengths in the micrometric range (from 5 to dozens of micrometres) using extract concentrations between 10 and 50 mg mL−1. Moreover, the aspect ratio of these nanowires can be adjusted (from around 14–20 to 160–400) by changing the experimental conditions, namely the use of oleic acid. Phenolic compounds were found to have a key role in this bioreduction process allowing to obtain practically only nanowires (without other morphologies). Nevertheless, the use of oleic acid/oleylamine is essential to manipulate their size and aspect ratio. Most importantly, these bio-based copper nanowires were found to be resistant under storage in ethanol and when submitted to air exposure, both for 2 weeks, certainly due to the adsorption of antioxidant biomolecules (phenolic) at their surface, thus avoiding the use of other polymeric protective layers. The conductivity of the CuNWs was found to be 0.009 S cm−1. As a result, this study opens a new standpoint in this field, “closing the door” to the use of hazardous reagents and synthetic polymeric protective layers, on the production of stable copper nanowires with potential application as conductive materials.publishe

Antioxidant and antimicrobial films based on brewers spent grain arabinoxylans, nanocellulose and feruloylated compounds for active packaging

In this study, brewers spent grain (BSG) arabinoxylans-based nanocomposite films were prepared by solvent casting of arabinoxylans (AX) suspensions containing different amounts of nanofibrillated cellulose (NFC, 5, 10, 25, 50 and 75% mass fraction). The obtained nanocomposite films were homogeneous and presented thermal stability up to 230 °C and good mechanical properties (Young's modulus up to 7.5 GPa). Additionally, the films with 50% NFC were loaded with ferulic acid or feruloylated arabinoxylo-oligosaccharides enriched fraction from BSG (75 mg per g of film). This combination enhanced the UV–Vis barrier properties and imparted additional functionalities to the films, namely (i) antioxidant activity up to 90% (DPPH scavenging activity), (ii) antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, and (iii) antifungal activity towards the polymorphic fungus Candida albicans. Therefore, these fully biobased nanocomposite films show potential for application as active food packaging systems.publishe

Estudos sobre a nutrição mineral do cafeeiro: XL. Fitomassa e conteúdo de macro e micronutrientes no material podado

An experiment has carried out in commercial coffee plantation (varie ty Mundo Novo, 7 years old, 1904 "covas" per ha, previous yield 3,180 kg cleancoffe, Ipanema Agro Indústria S.A., Alfenas, MG, Brazil) designed to estimate the quantities of biomass, macro and micronutrients there in, removed by different types of pruning, namely: (1) stumping at 0,40 m above ground;(2) capping at 1,00 m; (3) capping at 1,50 m; (4) capping at 2,00 m; (5) capping at 1,50 m and cutting of laterals at 15 cm from the main stem. Analyses of data and material allowed for the following conclusions to be drawn. (1) Biomass removed by pruning was higher when pruning was done by stumping (24.3 tons of fresh weight and 11.9 tons dry weight) and by capping at 1,00 m above ground (20.6 and 10.1 tons, respectively); these treatments were followed by capping at 1,50 m plus cutting off laterals which yielded 19.4 and 8.3 tons of fresh and dry weight; the fresh and try weight corresponding to capping at 1,50 and 2,00 m above ground were: 12.1 and 5.4, 5.6 and 2.5 tons por hectare. (2) Simple regression equations describe with a high degree of significance the relationship between height of pruning and biomass removed there off. (3) The amount of macro and micronutrients, as expected, relate well with the quantity of plant material which corresponds to each treatment. Total amounts for macronutrients were, according to the order of the treatments given above (in kg/ha): N - 320; 294; 162; 80 and 261; P - 18; 15; 10; 44 and 16; K - 286; 266; 168; 78 and 273; Ca - 149; 139; 63; 33 and 101; Mg - 30; 33; 16; 8 and 26; S - 10; 7; 6; 3 and 10. In the same order, the amounts of micronutrients were, in g/ha: B - 306; 337; 163; 83 and 268; Cu - 229; 219; 121; 51 and 191; Fe - 2783; 2328; 1367; 544 and 2088; Mn - 437; 779; 264; 142 and 412; Zn - 174; 152; 74; 28 and 121. (4) Simple regression equations were derived which express the relationship between quantities of macro and micronutrients removed and the heighth of pruning. (5) Recycling of the biomass curt off fy pruning could contribute to savings in the rates of fertilizer to be applied in the period of regrowth. Most of the nutrients, however, from two thirds to three fourths of the total, are found in branches and stems which is likely to more slonly released.Foi conduzido um ensaio numa plantação comercial de café de variedade Mundo Novo de 9 anos de idade, com uma população de 1904 covas/ha, destinada a avaliar a quantidade de biomassa e de nutrientes removidas por diferentes tipos de poda: recepa a 0,40m; decote a 1,00, 1,50 e 2,00 m; decote a 1,50m com esqueletamento. A análise do material e dos dados permitiu tirar-se as seguintes conclusões: (1) a biomassa removida pela poda foi maior na recepa (24,3 t de matéria fresca e 11,9 de matéria seca) e no decote a 1,00 m (20,6 e 10,1 t, respectivamente); seguia-se o decote a 1,50 m com esqueletamento que deu 19,4 e 8,3 t de matéria fresca e seca por hectare; os pesos da matéria fresca e seca correspondentes aos decotes a 1,50 m e 2,00 m foram: 12,1 e 5,4; 5,6 e 2,5 t/ha; (2) a relação existente entre a altura de poda e quantidade de fitomassa removida é descrita por equações de regressão simples; (3) as quantidades de nutrientes removidas são proporcionais as quantidades de material podado sendo as seguintes de acordo com a ordem dos tratamentos dado, em kg/ha: N - 320, 294, 162, 80 e 261; P - 18, 15, 10, 44 e 16; K - 286, 266, 168, 78 e 273; Ca - 149, 139, 63, 33 e 101: Mg - 30, 33, 16, 8 e 26; S - 10, 7,6, 3 e 10; as quantidades de micronutrientes removidas foram, em g/ha: B - 306, 337, 163, 83 e 268; Cu - 229, 219, 121, 51 e 191; Fe - 2783, 2328, 1367, 544 e 2,088; Mn - 437, 779, 264, 142 e 412; Zn - 174, 152, 74, 28 e 121; (3) foram derivadas equações de regressão simples que relacionam quantidade extraídas e altura da poda; (4) a reciclagem de fitomassa contribui com economia substancial de fertilizantes para a nova vegetação. Cerca de dois terços e três quartos de nutrientes, entretanto, estão contidos no material lenhoso de caules e ramos o que deve fazer que a sua disponibilidade seja mais lenta

Configural and featural information in facial-composite images

Eyewitnesses are often invited to construct a facial composite, an image created of the person they saw commit a crime that is used by law enforcement to locate criminal suspects. In the current paper, the effectiveness of composite images was investigated from traditional feature systems (E-FIT and PRO-fit), where participants (face constructors) selected individual features to build the face, and a more recent holistic system (EvoFIT), where they ‘evolved' a composite by repeatedly selecting from arrays of complete faces. Further participants attempted to name these composites when seen as an unaltered image, or when blurred, rotated, linearly stretched or converted to a photographic negative. All of the manipulations tested reduced correct naming of the composites overall except (i) for a low level of blur, for which naming improved for holistic composites but reduced for feature composites, and (ii) for 100% linear stretch, for which a substantial naming advantage was observed. Results also indicated that both featural (facial elements) and configural (feature spacing) information was useful for recognition in both types of composite system, but highly-detailed information was more accurate in the feature-based than the holistic method. The naming advantage of linear stretch was replicated using a forensically more-practical procedure with observers viewing an unaltered ¬composite sideways. The work is valuable to police practitioners and designers of facial-composite systems