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In the present work we demonstrate the ultrasound assisted synthesis of gold nanoparticles (AuNPs) in an ecofriendly manner using Calothrix algae. The production of the AuNPs in the reaction mixture is significantly accelerated by inducing ultrasound irradiation. The optical property, size distribution, morphology and crystalline phase of the AuNPs were determined by visual, UV–vis spectroscopy, dynamic light scattering, transmission electron microscopy (TEM) and x-ray diffraction (XRD) technique. The appearance of a light pink color at λmax = 550 nm indicated the synthesis of AuNPs. TEM images showed the formation of anisotropic AuNPs with predominant truncated shape and particles are in the range of 30–120 nm. The XRD spectrum of the AuNPs exhibited a Bragg reflections peak at 38.23°, corresponding to elemental gold. Further, AuNPs showed significant catalytic efficiency (rate constant, k = 0.072 4752 min−1) in reducing 4-nitrophenol (2 mM) to 4-aminophenol. The advantage of using ultrasound relates to the ecofriendly and rapid synthesis of AuNPs and various biotechnological applications were suggested.

RESUMOQuando o homem deixou de ser nômade, teve de se adaptar às novas condições, passando a empregar a madeira para energia, instrumentos de caça e defesa e elementos construtivos diversos. Desde então, em função dos usos e do rápido crescimento, a importância da madeira vem se acentuando, principalmente porque sua exploração agride menos o ambiente quando comparada a outros materiais não renováveis. Embora existam várias pesquisas sobre Eucalyptus e Pinus, estudos com outras espécies são incipientes, principalmente quanto ao efeito dos extrativos na resistência natural das madeiras. Assim, o objetivo da pesquisa foi avaliar a influência do teor de extrativos na resistência natural das madeiras de Acacia mangium, Casuarina sp., Eucalyptus cloeziana, Corymbia torelliana e Tectona grandis ao térmita xilófago Nasutitermes corniger, espécie de ocorrência frequente em várias regiões no Brasil. De cada espécie foram retirados corpos de prova, com dimensões de 2,00 x 10,16 x 0,64 cm (radial x longitudinal x tangencial) em quatro posições no sentido medula-alburno (cerne interno, cerne intermediário, cerne externo e alburno). As madeiras foram expostas à ação dos cupins durante 45 dias em ensaio de preferência alimentar. Amostras não selecionadas para o ensaio com cupins foram transformadas em serragem e o teor de extrativos obtido ao empregar a fração que passou pela peneira de 40 e ficou retida na de 60 mesh. A resistência natural não esteve associada ao teor de extrativos presentes na madeira. A resistência das madeiras variou no sentido medula-alburno, com padrão variável para cada espécie. As madeiras mais resistentes foram Tectona grandis e Corymbia torelliana e a mais deteriorada a Acacia mangium. Palavras-chave: extrativos; térmitas xilófagos; preferência alimentar. ABSTRACTWhen man stopped being nomadic, he had to adapt to new conditions, and started employing wood for energy, hunting and defense instruments and miscellaneous constructive elements. Since then, in the light of usages and rapid growth, the importance of wood has been increasing, primarily by their exploitation assaults less the environment when compared to other non-renewable materials. Although there are several 1 Engenheiro Florestal, Dr., Professor do

The fullerene molecule belongs to the so-called super materials. The compound is interesting due to its spherical configuration where atoms occupy positions forming a mechanically stable structure. We first demonstrate that pollen of Hibiscus rosa-sinensis has a strong symmetry regarding the distribution of its spines over the spherical grain. These spines form spherical hexagons and pentagons. The distance between atoms in fullerene is explained applying principles of flat, spherical, and spatial geometry, based on Euclid’s “Elements” book, as well as logic algorithms. Measurements of the pollen grain take into account that the true spine lengths, and consequently the real distances between them, are measured to the periphery of each grain. Algorithms are developed to recover the spatial effects lost in 2D photos. There is a clear correspondence between the position of atoms in the fullerene molecule and the position of spines in the pollen grain. In the fullerene the separation gives the idea of equal length bonds which implies perfectly distributed electron clouds while in the pollen grain we suggest that the spines being equally spaced carry an electrical charge originating in forces involved in the pollination process.

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