Anak Krakatau triggers volcanic freezer in the upper troposphere

Volcanic activity occurring in tropical moist atmospheres can promote deep convection and trigger volcanic thunderstorms. These phenomena, however, are rarely observed to last continuously for more than a day and so insights into the dynamics, microphysics and electrification processes are limited. Here we present a multidisciplinary study on an extreme case, where volcanically-triggered deep convection lasted for six days. We show that this unprecedented event was caused and sustained by phreatomagmatic activity at Anak Krakatau volcano, Indonesia during 22-28 December 2018. Our modelling suggests an ice mass flow rate of similar to 5x10(6)kg/s for the initial explosive eruption associated with a flank collapse. Following the flank collapse, a deep convective cloud column formed over the volcano and acted as a 'volcanic freezer' containing similar to 3x10(9)kg of ice on average with maxima reaching similar to 10(10)kg. Our satellite analyses reveal that the convective anvil cloud, reaching 16-18km above sea level, was ice-rich and ash-poor. Cloud-top temperatures hovered around -80 degrees C and ice particles produced in the anvil were notably small (effective radii similar to 20 mu m). Our analyses indicate that vigorous updrafts (>50m/s) and prodigious ice production explain the impressive number of lightning flashes (similar to 100,000) recorded near the volcano from 22 to 28 December 2018. Our results, together with the unique dataset we have compiled, show that lightning flash rates were strongly correlated (R=0.77) with satellite-derived plume heights for this event

Carrapato e vermes: inimigos do gado e do produtor.

bitstream/item/65290/1/CT-95-Carrapato-e-vermes.pd

Reaeration in Supercritical Open Channel Flows: An Experimental Study

Reaeration is a primary path of reoxygenation in streams, fundamental to environmental and ecological integrity. Previous laboratory studies of reaeration rates in subcritical flows showed large scatter in results, with differences in mass transfer coefficients of more than one order of magnitude between comparable flow conditions. Although supercritical flow is commonly observed in natural streams and engineered channels, systematic measurements of supercritical flow reaeration rates have been unavailable. Experiments in a laboratory open channel flume encompassing sub-and supercritical flows have been undertaken. The subcritical data were consistent with a large body of previous studies. Supercritical flows showed 6-10 times stronger reaeration rates than comparable subcritical conditions, while local rates at hydraulic jumps systematically exceed those in the supercritical flows upstream by a factor up to three. A close relationship between reaeration rates and turbulent dissipation rate is observed, and a systematic Froude number dependency is demonstrated for both sub-and supercritical flows. Observed mass transfer coefficients do not correlate as well with flow Reynolds number and shear Reynolds number. The higher reaeration rates associated with supercritical flows indicates that a change in open channel flow regime for the same Reynolds number may be used to improve water quality

Influence of extraction process on the luminescent properties of carbon nanomaterials derived from olive mill wastewaters

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NANOLIVE/ISELIn an accompanying communication [1], we have revealed that nanosized carbon materials could be easily obtained from olive mil wastewater (OMWW) using green, sustainable and simple technological processes. In this contribution we will essentially focus on the study of the impact of the effluent nature on the structural, morphological and luminescente characteristics of synthesized carbon nanodots (CNDs).info:eu-repo/semantics/publishedVersio

Carbon nanodots from olive mill wastewater: a sustainable route

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NANOLIVE/ISELOlive oils are obtained from the fruit of the olive tree (Olea europaea L.) by combined mechanical and physical operations. Portugal has a significant production of olive oil (76 k tonnes/year over the last 5 years, 2010-2015) [1]. Olive oil is typically obtained by two main processes: batch press and continuous centrifugation. Depending on the particular process used, 200-1600 L of olive mill wastewater (OMWW) is produced per tonne of processed olives. Taken the lowest of these values, an estimate points to around 15 million L of OMWW may be produced each year in Portugal. The OMWW exhibits very low biodegradability parameters which pose serious issues for its treatment. Sustainable production of high-valued carbon materials from industrial lowvalued and problematic wastes is particularly appealing and highly desirable.info:eu-repo/semantics/publishedVersio

Bright nanoparticles for an even brighter future: efficient production of luminescent carbon nanodots from olive mill wastewater

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NANOLIVE/ISELCarbon nanodots (CNDs) are a very recent class of spherical-shaped nanosized carbon materials possessing average typical diameters < 10 nm. Since the very first reports on carbon dots,1,2 a variety of methods (top-down and bottom-up strategies), carbon sources and passivating agents, have dealt with their synthesis.3 The bottom-up approach, encompassing the use of pyrolytic/solvothermal processes, is more amenable for large-scale production and can cope with a large diversity of carbon precursors, either from natural or synthetic sources, typically endowed with acid, alcohol and amine functionalities.4 Some of the interesting CNDs properties include tunable photoluminescence, outstanding photostability and negligible cytotoxicity. These unique properties have prompted their intense and widespread use in several fields, such as fluorescent bioimaging and nanomedicine, chemo/biosensing, photocatalysis and optoelectronics.4info:eu-repo/semantics/publishedVersio

Time of flight detectors with SiPMT array readout

none6noTime-of-flight detectors, based on scintillation counters, may use conventional photomultipliers for the readout. Problems arise in presence of external magnetic fields. SiPMT arrays are insensitive to magnetic fields and may be a suitable option to replace photomultipliers. Timing performances for several types of SiPMT arrays have been studied and results are presented.Bonesini, M; Bertoni, R.; de Bari, A.; Nardò, R.; Prata, M.; Rossella, M.Bonesini, M; Bertoni, R.; DE BARI, Antonio; Nardo', Roberto; Prata, M.; Rossella, M