LDPE/EVA Composites for Antimicrobial Properties

Composites with antimicrobial activity are of great interest nowadays and the development of titanium dioxide with these functional properties presents interest in academic and industrial sectors.An approach to develop PE composite containing silver microparticles to have an antimicrobial effect is presented. To obtain such antimicrobial composites, LDPE/EVA were processed with Ag particles on TiO2 particles as inorganic carrier substance. Titanium dioxide nanoparticles (P-25) were covered with silver particles using Turkevich Method or citrate reduction method. The Ag/TiO2 particles were dispersed at concentration of 0,8 wt% and 1% wt% in LDPE/ethylene vinyl acetate copolymer (EVA)-(50% w/w) at the melt state in a Haake torque Rheometer. Silver microparticles were characterized with UV-Vis Spectroscopy. The composites thus prepared were characterized through XRD, Ares Rheometer, Scanning Electronic Microscopy (SEM) and JIS Z 2801 antimicrobial tests to study the effects of the addition of particles on rheological properties, morphological behavior and antimicrobial properties. The results showed that incorporation of silver/titanium dioxide particles on composites obtained systems with differents dispersions. The Ag/TiO2 particles showed uniform distribution of Ag on TiO2 particles as observed by SEM-EDX and antimicrobial tests according to JIS Z 2801 shows excellent antimicrobial properties.

Translocação orgânica, produtividade e rendimento de óleo essencial de Mentha piperita L. cultivada em solução nutritiva com variação dos níveis de N, P, K e Mg

O estudo objetivou avaliar translocação orgânica, índices fisiológicos da análise de crescimento e rendimento do óleo essencial de Mentha piperita L. cultivada em solução nutritiva com variação dos níveis de N, P, K e Mg. Assim, foram avaliados os quatro tratamentos contendo 50% N, P, K, 25% Mg; 50% N, P, K, Mg; 65%N, 50%P, 25%K, 100% Mg e 100% N, P, K, Mg. A translocação orgânica foi avaliada por meio da determinação da razão de massa foliar (RMF) e da distribuição de massa seca para os diferentes órgãos. Os índices fisiológicos razão de área foliar (RAF), área foliar específica (AFE), taxa assimilatória líquida (TAL) e taxa de crescimento relativo (TCR) derivadas que compõem a análise de crescimento foram estimados pelo programa ANACRES, após ajuste exponencial quadrático da área foliar e massa seca de lâminas foliares e total da planta em relação ao tempo. O rendimento do óleo essencial, em porcentagem, foi calculado após extração da parte aérea por hidrodestilação. As plantas submetidas ao tratamento com nível completo de nutrientes (100%N/P/K/Mg) exportaram com menor eficiência o material orgânico a partir da folha e a RMF mostrou queda mais lenta, devido à retenção desse material por mais tempo no local de sua produção. Além disso, não apresentaram melhor produtividade e as curvas da TAL e TCR mostraram quedas mais lentas. As plantas submetidas ao tratamento com 65%N/50%P/25%K/100%Mg revelaram adequada exportação de matéria orgânica da folha para caule e pecíolos, conforme demonstra a RMF e a distribuição de massa seca para esses órgãos. Revelaram ainda a RAF mais elevada no inicio do desenvolvimento e mais baixa aos 94 DAT, indicando sombreamento das folhas como resultado de seu crescimento. A AFE dessas plantas mostrou menor variação durante o ciclo, refletindo espessura mais constante de suas folhas. A TAL e a TCR apresentaram curvas decrescentes, com quedas bem acentuadas em relação às demais plantas. Todos esses índices indicam melhor produtividade das plantas submetidas ao tratamento 65%N/50%P/25%K/100%Mg, que também apresentaram rendimento de óleo essencial, em média, maior durante o ciclo. Conclui-se que a redução de 35% de N, 50% de P, 75% de K (65%N/50%P/25%K/100%Mg) é indicada para o cultivo e extração de óleo essencial de M. piperita.

Alocação de biomassa de Brachiaria subquadripara sob diferentes concentrações de N, P e K

O presente trabalho objetivou avaliar a alocação de biomassa em plantas de Brachiaria subquadripara em função de diferentes concentrações de N, P e K em solução nutritiva. O delineamento experimental utilizado foi inteiramente casualizado, com seis repetições, e os tratamentos constituíram-se de cinco níveis de N, P e K (0, 25, 50, 75 e 100% da concentração na solução-base) durante cinco épocas (intervalos de sete dias). A solução-base utilizada refere-se à diluição de 20% da solução nutritiva para culturas agrícolas. A ausência de N propiciou maior alocação de biomassa em raízes do que em colmos até a quarta semana (28 DAT). A adição de 25 e 75% de fósforo na solução condicionou acréscimos de biomassa de 6,6 e 5,8%, respectivamente, em relação à ausência de fósforo. em condições de deficiência de potássio, as plantas apresentaram tendência a manter constante a proporção de colmos e raízes, porém decresceu a produção de folhas com a idade da planta.

Desenvolvimento, trocas gasosas, rendimento e composição de óleo essencial de Mentha piperita L. cultivada em solução nutritiva com variação dos níveis de N, P, K e Mg

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Physiological indexese macro- and micronutrients in plant tissue and essential oil of Mentha piperita L. grown in nutrient solution with variation in N, P, K and Mg levels

Mentha piperita L. is an aromatic and medicinal species of the family Lamiaceae, known as mint or peppermint, and its leaves and branches produce essential oil rich in menthol. This study aimed to evaluate physiological indexes, macro- and micronutrients inthe shootsand essential oil of Mentha piperita L. grown in nutrient solution number 2 of Hoagland and Arnon (1950) with different N, P, K and Mg levels. Shoot length, dry mass of the different organs, total dry mass, leaf area, essential oil yield and composition, and macronutrient (N, P, K, Mg, Ca, S) and micronutrient (Mn, Cu, Fe, Zn) contents in the shoot were evaluated. Plants treated with 65%N/50%P/25%K/100%Mg had a tendency towards longer shoot, greaterroot and leaf blade dry masses, higher essential oil yield, higher menthol levels and lower menthone levels. The results showed that Mentha can be grown in nutrient solution by reducing 65% N, 50% P, 25% K and 100% Mg. This solution had better development compared to the other tested treatments. Therefore,we recommendMentha piperita L. to be grown with such nutrient levels.

Carlosbarbosaite, ideally (UO2)(2)Nb2O6(OH)(2)center dot 2H(2)O, a new hydrated uranyl niobate mineral with tunnels from Jaguaracu, Minas Gerais, Brazil: description and crystal structure

Carlosbarbosaite, ideally (UO2)(2)Nb2O6(OH)(2)center dot 2H(2)O, is a new mineral which occurs as a late cavity filling in albite in the Jaguaracu pegmatite, Jaguaracu municipality, Minas Gerais, Brazil. The name honours Carlos do Prado Barbosa (1917-2003). Carlosbarbosaite forms long flattened lath-like crystals with a very simple orthorhombic morphology. The crystals are elongated along [001] and flattened on (100); they are up to 120 mu m long and 2-5 mu m thick. The colour is cream to pale yellow, the streak yellowish white and the lustre vitreous. The mineral is transparent (as individual crystals) to translucent (massive). It is not fluorescent under either long-wave or short-wave ultraviolet radiation. Carlosbarbosaite is biaxial(+) with alpha = 1.760(5), beta = 1.775(5), gamma = 1.795(5), 2V(meas) = 70(1)degrees, 2V(calc) = 83 degrees. The orientation is X parallel to a, Y parallel to b, Z parallel to c. Pleochroism is weak, in yellowish green shades, which are most intense in the Z direction. Two samples were analysed. For sample I, the composition is: UO3 54.52, CaO 2.07, Ce2O3 0.33, Nd2O3 0.49, Nb2O5 14.11, Ta2O5 15.25, TiO2 2.20, SiO2 2.14, Fe2O3 1.08, Al2O3 0.73, H2O (calc.) 11.49, total 104.41 wt.%; the empirical formula is (square 0.68Ca0.28Nd0.02Ce0.02)(Sigma=1.00)[U-1.44 square O-0.56(2.88)(H2O)(1.12)](Nb0.80Ta0.52Si0.27Ti0.21Al0.11Fe0.10)(Sigma=2.01) O-4.72(OH)(3.20)(H2O)(2.08). For sample 2, the composition is: UO3 41.83, CaO 2.10, Ce2O3 0.31, Nd2O3 1.12, Nb2O5 14.64, Ta2O5 16.34, TiO2 0.95, SiO2 3.55, Fe2O3 0.89, Al2O3 0.71, H2O (calc.) 14.99, total 97.43 wt.%; the empirical formula is (square 0.67Ca0.27Nd0.05Ce0.01)(Sigma=1.00)[U-1.04 square O-0.96(2.08)(H2O)(1.92)] (Nb0.79Ta0.53Si0.42Ti0.08Al0.10Fe0.08)(Sigma=2.00)O-4.00(OH)(3.96)(H2O)(2.04). The ideal endmember formula is (UO2)(2)Nb2O6(OH)(2)center dot 2H(2)O. Calculated densities are 4.713 g cm(-3) (sample 1) and 4.172 g cm(-3) (sample 2). Infrared spectra show that both (OH) and H2O are present. The strongest eight X-ray powder-diffraction lines [listed as d in angstrom(I)(hkl)] are: 8.405(8)(110), 7.081(10)(200), 4.201(9)(220), 3.333(6)(202), 3.053(8)(022), 2.931(7)(420), 2.803(6)(222) and 2.589(5)(040,402). The crystal structure was solved using single-crystal X-ray diffraction (R = 0.037) which gave the following data: orthorhombic, Cmem, a = 14.150(6), b = 10.395(4), c = 7.529(3) angstrom, V = 1107(1) angstrom(3), Z = 4. The crystal structure contains a single U site with an appreciable deficiency in electron scattering, which is populated by U atoms and vacancies. The U site is surrounded by seven 0 atoms in a pentagonal bipyramidal arrangemet. The Nb site is coordinated by four 0 atoms and two OH groups in an octahedral arrangement. The half-occupied tunnel Ca site is coordinated by four 0 atoms and four H2O groups. Octahedrally coordinated Nb polyhedra share edges and comers to form Nb2O6(OH)(2) double chains, and edge-sharing pentagonal bipyramidal U polyhedra form UO5 chains. The Nb2O6(OH)(2) and UO5 chains share edges to form an open U-Nb-phi framework with tunnels along [001] that contain Ca(H2O)(4) clusters. Carlosbarbosaite is closely related to a family of synthetic U-Nb-O framework tunnel structures, it differs in that is has an (OH)-bearing framework and Ca(H2O)(4) tunnel occupant. The structure of carlosbarbosaite resembles that of holfertite.

Sol-gel TiO2 nanoparticles prompt photocatalytic cement for pollution degradation

TiO2 nanoparticles (TiO2NPs) prepared by the sol–gel method have been incorporated to cement paste with the aim of creating a photocatalytic system capable of compensating, through degradation of hazardous molecules, the envi- ronmental impact associated to the production of the clinker. Doping was carried out at different mass ratios with TiO2NPs precursor solutions within a fresh ce- ment paste, which was then characterized using scanning electron microscopy (SEM). The photocatalytic performance was evaluated by the degradation of Methylene Blue (MB) using a 125W UV lamp as irradiating source. Main cement properties such as hydration degree and C-S-H content are affected by TiO2NPs doping level. Cement containing TiO2NPs exhibited an increasing photocatalytic activity for increasing doping, while the pure cement paste control could hardly degrade MB. The kinetics of the system where also studied and their second order behavior related to microstructural aspects of the system.

The life and stories of the Jaina savior, Pārçvanātha,

On Pārśvanātha, 8th century B.C., 23rd Jaina Tīrthaṅkara.

Loading effect in copper(II) oxide cluster-surface-modified titanium(IV) oxide on visible- and UV-light activities

Cu(acac)2 is chemisorbed on TiO2 particles [P-25 (anatase/rutile = 4/1 w/w), Degussa] via coordination by surface Ti–OH groups without elimination of the acac ligand. Post-heating of the Cu(acac)2-adsorbed TiO2 at 773 K yields molecular scale copper(II) oxide clusters on the surface (CuO/TiO2). The copper loading amount (Γ/Cu ions nm–2) is controlled in a wide range by the Cu(acac)2 concentration and the chemisorption–calcination cycle number. Valence band (VB) X-ray photoelectron and photoluminescence spectroscopy indicated that the VB maximum of TiO2 rises up with increasing Γ, while vacant midgap levels are generated. The surface modification gives rise to visible-light activity and concomitant significant increase in UV-light activity for the degradation of 2-naphthol and p-cresol. Prolonging irradiation time leads to the decomposition to CO2, which increases in proportion to irradiation time. The photocatalytic activity strongly depends on the loading, Γ, with an optimum value of Γ for the photocatalytic activity. Electrochemical measurements suggest that the surface CuO clusters promote the reduction of adsorbed O2. First principles density functional theory simulations clearly show that, at Γ < 1, unoccupied Cu 3d levels are generated in the midgap region, and at Γ > 1, the VB maximum rises and the unoccupied Cu 3d levels move to the conduction band minimum of TiO2. These results suggest that visible-light excitation of CuO/TiO2 causes the bulk-to-surface interfacial electron transfer at low coverage and the surface-to-bulk interfacial electron transfer at high coverage. We conclude that the surface CuO clusters enhance the separation of photogenerated charge carriers by the interfacial electron transfer and the subsequent reduction of adsorbed O2 to achieve the compatibility of high levels of visible and UV-light activities.

Molecular And Biochemical Characterization Of Caffeine Synthase And Purine Alkaloid Concentration In Guarana Fruit.

Guarana seeds have the highest caffeine concentration among plants accumulating purine alkaloids, but in contrast with coffee and tea, practically nothing is known about caffeine metabolism in this Amazonian plant. In this study, the levels of purine alkaloids in tissues of five guarana cultivars were determined. Theobromine was the main alkaloid that accumulated in leaves, stems, inflorescences and pericarps of fruit, while caffeine accumulated in the seeds and reached levels from 3.3% to 5.8%. In all tissues analysed, the alkaloid concentration, whether theobromine or caffeine, was higher in young/immature tissues, then decreasing with plant development/maturation. Caffeine synthase activity was highest in seeds of immature fruit. A nucleotide sequence (PcCS) was assembled with sequences retrieved from the EST database REALGENE using sequences of caffeine synthase from coffee and tea, whose expression was also highest in seeds from immature fruit. The PcCS has 1083bp and the protein sequence has greater similarity and identity with the caffeine synthase from cocoa (BTS1) and tea (TCS1). A recombinant PcCS allowed functional characterization of the enzyme as a bifunctional CS, able to catalyse the methylation of 7-methylxanthine to theobromine (3,7-dimethylxanthine), and theobromine to caffeine (1,3,7-trimethylxanthine), respectively. Among several substrates tested, PcCS showed higher affinity for theobromine, differing from all other caffeine synthases described so far, which have higher affinity for paraxanthine. When compared to previous knowledge on the protein structure of coffee caffeine synthase, the unique substrate affinity of PcCS is probably explained by the amino acid residues found in the active site of the predicted protein.