Validity of Triply Labelled Water Analysis for Energy Expenditure Measurements in Mice

The Doubly Labelled Water (DLW) method is widely used to determine energy expenditure. In this work, we demonstrate the addition of the third stable isotope, 17O, to turn it into Triply Labelled Water (TLW), using the three isotopes measurement of optical spectrometry. We performed TLW (2H, 18O and17O) measurements for the analysis of the CO2 production (rCO2) of mice on different diets for the first time. Triply highly enriched water was injected into mice, and the isotope enrichments of the distilled blood samples of one initial and two finals were measured by an Off-Axis Integrated Cavity Output Spectroscopy instrument. We evaluated the impact of different calculation protocols and the values of evaporative water loss fraction. We found that the dilution space and turnover rates of 17O and 18O were equal for the same mice group, and that values of rCO2 calculated based on 18O-2H, or on 17O-2H agreed very well. This increases the reliability and redundancy of the measurements and it lowers the uncertainty in the calculated rCO2 to 3% when taking the average of two DLW methods. However, the TLW method overestimated the rCO2 compared to the indirect calorimetry measurements that we also performed, much more for the mice on a high-fat diet than for low-fat. We hypothesize an extra loss or exchange mechanism with a high fractionation for 2H to explain this difference.

Quantum-Optical Spectrometry in Relativistic Laser–Plasma Interactions Using the High-Harmonic Generation Process: A Proposal

Quantum-optical spectrometry is a recently developed shot-to-shot photon correlation-based method, namely using a quantum spectrometer (QS), that has been used to reveal the quantum optical nature of intense laser–matter interactions and connect the research domains of quantum optics (QO) and strong laser-field physics (SLFP). The method provides the probability of absorbing photons from a driving laser field towards the generation of a strong laser–field interaction product, such as high-order harmonics. In this case, the harmonic spectrum is reflected in the photon number distribution of the infrared (IR) driving field after its interaction with the high harmonic generation medium. The method was implemented in non-relativistic interactions using high harmonics produced by the interaction of strong laser pulses with atoms and semiconductors. Very recently, it was used for the generation of non-classical light states in intense laser–atom interaction, building the basis for studies of quantum electrodynamics in strong laser-field physics and the development of a new class of non-classical light sources for applications in quantum technology. Here, after a brief introduction of the QS method, we will discuss how the QS can be applied in relativistic laser–plasma interactions and become the driving factor for initiating investigations on relativistic quantum electrodynamics.

Interferência dos metais sódio, magnésio e cálcio na determinação de urânio em amostras de águas tratadas pela técnica de espectrometria óptica por plasma indutivamente acoplado / Interference of sodium, magnesium and calcium metals in the determination of uranium in treated water samples by the optical spectrometry inductively coupled plasma technique

Diante dos riscos que o Urânio apresenta à saúde dos seres humanos e ao Meio Ambiente, o Ministério da Saúde e o Conselho Nacional de Meio Ambiente do Brasil estabeleceram limites normativos para a concentração de Urânio em águas tratadas, subterrâneas e mananciais nas seguintes legislações: Portaria MS Nº 2914/2011, Resolução CONAMA 396/2008 e Resolução CONAMA 357/2005, respectivamente. Internacionalmente, já existe a preocupação com Urânio, por diversos órgãos reguladores e agências de saúde, como a Organização Mundial de Saúde (OMS) e a Agência de Proteção Ambiental dos Estados Unidos (EPA). Com o objetivo de se atender aos baixos limites analíticos preconizados na Legislação, é necessário o desenvolvimento de metodologias analíticas sensíveis e confiáveis para a determinação de Urânio. A técnica da Espectrometria Óptica por Plasma Indutivamente Acoplado (ICP OES) tem sido muito empregada na análise de amostras de águas, por apresentar maior sensibilidade do que a técnica por Absorção Atômica por Chama (FAAS), boa relação custo benefício em relação à Espectrometria de Massa com Plasma Indutivamente Acoplado (ICP-MS) e dispensar o tratamento prévio no caso das amostras de água potável.Neste trabalho foi desenvolvido um método analítico para a determinação de Urânio em amostras de águas tratadas pela técnica de ICP OES, com um equipamento com tocha de vista axial e sistema de cone para eliminação da zona fria do plasma. Também foi investigada a interferência dos metais Sódio, Magnésio e Cálcio, conhecidos como Elementos Facilmente Ionizáveis (EIE). Estes metais estão presentes em concentrações elevadas em regiões de clima seco e semi-árido ou de áreas de captação de água de mananciais que sofrem influência de águas marinhas. Para este estudo foram empregados mais dois equipamentos: um ICP OES com tocha de vista axial e sistemas Shear Gas para a eliminação da zona fria do plasma e um ICP-MS. Os resultados obtidos mostram que as presenças destes interferentes (Ca, Mg, Na) em concentrações elevadas podem causar erros na determinação de Urânio com resultados falsos positivos, em equipamentos de ICP OES que empregam o sistema de cone para eliminação da zona fria do plasma.

The Role of Inorganic-Organic Bio-Fillers Containing Kraft Lignin in Improvement in Functional Properties of Polyethylene

In this study, MgO-lignin (MgO-L) dual phase fillers with varying amounts of lignin as well as pristine lignin and magnesium oxide were used as effective bio-fillers to increase the ultraviolet light protection and enhance the barrier performance of low density polyethylene (LDPE) thin sheet films. Differential scanning calorimetry (DSC) was used to check the crystalline structure of the studied samples, and scanning electron microscopy (SEM) was applied to determine morphological characteristics. The results of optical spectrometry in the range of UV light indicated that LDPE/MgO-L (1:5 wt/wt) composition exhibited the best protection factor, whereas LDPE did not absorb ultraviolet waves. Moreover, the addition of hybrid filler decreased the oxygen permeability factor and water vapor transmission compared with neat LDPE and its composites with pristine additives, such as lignin and magnesium oxide. The strong influence of the microstructure on thin sheet films was observed in the DSC results, as double melting peaks were detected only for LDPE compounded with inorganic-organic bio-fillers: LDPE/MgO-L.

High-frequency gas effusion through nanopores in suspended graphene

Porous, atomically thin graphene membranes have interesting properties for filtration and sieving applications. Here, graphene membranes are used to pump gases through nanopores using optothermal forces, enabling the study of gas flow through nanopores at frequencies above 100 kHz. At these frequencies, the motion of graphene is closely linked to the dynamic gas flow through the nanopore and can thus be used to study gas permeation at the nanoscale. By monitoring the time delay between the actuation force and the membrane mechanical motion, the permeation time-constants of various gases through pores with diameters from 10–400 nm are shown to be significantly different. Thus, a method is presented for differentiating gases based on their molecular mass and for studying gas flow mechanisms. The presented microscopic effusion-based gas sensing methodology provides a nanomechanical alternative for large-scale mass-spectrometry and optical spectrometry based gas characterisation methods.

Depth Profiling Investigation of Seawater Using Combined Multi-Optical Spectrometry

Depth profiling investigation plays an important role in studying the dynamic processes of the ocean. In this paper, a newly developed hyphenated underwater system based on multi-optical spectrometry is introduced and used to measure seawater spectra at different depths with the aid of a remotely operated vehicle (ROV). The hyphenated system consists of two independent compact deep-sea spectral instruments, a deep ocean compact autonomous Raman spectrometer and a compact underwater laser-induced breakdown spectroscopy system for sea applications (LIBSea). The former was used to take both Raman scattering and fluorescence of seawater, and the LIBS signal could be recorded with the LIBSea. The first sea trial of the developed system was taken place in the Bismarck Sea, Papua New Guinea, in June 2015. Over 4000 multi-optical spectra had been captured up to the diving depth about 1800 m at maximum. The depth profiles of some ocean parameters were extracted from the captured joint Raman–fluorescence and LIBS spectra with a depth resolution of 1 m. The concentrations of [Formula: see text] and the water temperatures were measured using Raman spectra. The fluorescence intensities from both colored dissolved organic matter (CDOM) and chlorophyll were found to be varied in the euphotic zone. With LIBS spectra, the depth profiles of metallic elements were also obtained. The normalized intensity of atomic line Ca(I) extracted from LIBS spectra raised around the depth of 1600 m, similar to the depth profile of CDOM. This phenomenon might be caused by the nonbuoyant hydrothermal plumes. It is worth mentioning that this is the first time Raman and LIBS spectroscopy have been applied simultaneously to the deep-sea in situ investigations.