Meiofauna increases bacterial denitrification in marine sediments

Denitrification is a critical process that can alleviate the effects of excessive nitrogen availability in aquatic ecosystems subject to eutrophication. An important part of denitrification occurs in benthic systems where bioturbation by meiofauna (invertebrates o1mm) and its effect on element cycling are still not well understood. Here we study the quantitative impact of meiofauna populations of different abundance and diversity, in the presence and absence of macrofauna, on nitrate reduction, carbon mineralization and methane fluxes. In sediments with abundant and diverse meiofauna, denitrification is double that in sediments with low meiofauna, suggesting that meiofauna bioturbation has a stimulating effect on nitrifying and denitrifying bacteria. However, high meiofauna densities in the presence of bivalves do not stimulate denitrification, while dissimilatory nitrate reduction to ammonium rate and methane efflux are significantly enhanced. We demonstrate that the ecological interactions between meio-, macrofauna and bacteria are important in regulating nitrogen cycling in soft-sediment ecosystems

Analogy of different optical temperature sensing techniques in LaNbO4:Er3+/Yb3+ phosphor

Three of the possible approaches to optical temperature sensing of a thermographic phosphor were formally compared in upconversion (UC) of Er3+ and Yb3+ doped lanthanum orthoniobate (LNO) phosphor. The three approaches used in the study were namely fluorescence intensity ratio (FIR) of thermally coupled levels (TCL), Valley to Peak ratio (VPR) and the ratio of non-thermally coupled levels (NTCL), respectively. The TCLs in the study were the ratio of intensities of 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 UC transitions of Er3+ ion. VPR method was verified within 2H9/2 → 4I15/2 transition of Er3+ UC. The other ratios of transitions which are not fit in TCL were investigated through NTCL technique. Ratios of several sets of transitions namely 4S3/2 → 4I15/2/2H9/2 → 4I15/2, 4S3/2 → 4I15/2/2I9/2 → 4I15/2, 4S3/2 → 4I15/2/4F9/2 → 4I15/2, 4F7/2 → 4I15/2/2H11/2 → 4I15/2, 2H11/2 → 4I15/2/4I9/2 → 4I15/2 and 2H11/2 → 4I15/2/2G11/2 were considered for NTCL technique. Moreover, the effect of temperature in the emission color was analyzed and a change from yellow (0.3310; 0.5990) to green (0.2590; 0.6740) was observed when the temperature rise has been increased from 14 to 300 K. Results obtained indicate that the LNO:Er3+/Yb3+ phosphor could be employed in optical thermometry and this phosphor would be a candidate with high potential as sensor operating from low to room temperature using TCL, VPR and/or NTCL methods. The most prominent sensing technique in the case of LNO:Er/Yb material among the three techniques is found to be NTCL with the high relative sensitivity of 1.19% K−1 at 300 K.publishe

Teor de óleo essencial de alecrim-pimenta em função do horário de colheita Essential oil content of pepper-rosmarin as a function of harvest time

O alecrim-pimenta é uma importante planta medicinal, nativa do nordeste brasileiro, que, devido ao seu óleo essencial, apresenta grande potencial antifúngico e antibacteriano. Um dos fatores que afetam o teor de metabólitos secundários das plantas é o horário de colheita, assim, o conhecimento desse fator subsidia as decisões agronômicas da espécie, favorecendo o aumento do teor de óleo essencial no momento da colheita. Dessa forma, o objetivo do presente trabalho foi avaliar o efeito do horário de colheita na produção de óleo essencial de alecrim-pimenta (Lippia sidoides Cham.). O experimento foi desenvolvido no Instituto de Ciências Agrárias da Universidade Federal de Minas Gerais (ICA/UFMG), Montes Claros, Minas Gerais, Brasil. Utilizou-se o delineamento experimental em blocos casualizados com cinco tratamentos, definidos pelos horários de coleta das folhas (6:00, 9:00, 12:00, 15:00 e 18:00) e seis repetições, sendo esse o número de coletas em cada tratamento. As folhas foram obtidas de plantas matrizes do Horto Medicinal do ICA/UFMG. O óleo essencial foi obtido pelo método de hidrodestilação usando o aparelho de Clevenger. A análise de regressão apresentou um efeito cúbico para o teor de óleo essencial, sendo que o maior valor, 5,78% em relação à matéria seca, foi obtido às 9h59min. Portanto, recomenda-se a colheita das folhas de alecrim-pimenta próximo das 10h.<br>The pepper-rosmarin is an important medicinal plant, native of Northeast of Brazil, that, because of its essential oil, presents great antifungal and antibacterial potential. One of the factors that affect the secondary metabolites content of plants is the harvest time, thus, the knowledge of this factor subsidizes the decisions agronomic species, favoring the increase of essential oil content at the harvest moment. Thus, the aim of this research was to evaluate the effect of harvest time on the essential oil production of pepper-rosmarin (Lippia sidoides Cham.). The experiment was carried out in the Instituto of Ciências Agrárias of Universidade Federal of Minas Gerais (ICA/UFMG), Montes Claros, Minas Gerais, Brazil. It was installed in a randomized block design, with five treatments consisted by harvest times (6:00, 9:00, 12:00, 15:00 and 18:00) with six replications (number of collections in each treatment). The leaves were obtained from stock plants of medicinal vegetable garden of ICA/ UFMG. The essential oil was obtained by hydrodistillation in a Clevenger apparatus. The regression analysis presented a cubic effect to the essential oil content, being that the highest value, 5,78% in relation to dry matter, was obtained at 9h59min. Therefore, it was recommended the harvest time of pepper-rosmarin leaves next to 10h