Physicochemical characterization of Lavandula spp. honey with FT-Raman spectroscopy

This study aimed to evaluate the potential of FT-Raman spectroscopy in the prediction of the chemical composition of Lavandula spp. monofloral honey. Partial Least Squares (PLS) regression models were performed for the quantitative estimation and the results were correlated with those obtained using reference methods. Good calibration models were obtained for electrical conductivity, ash, total acidity, pH, reducing sugars, hydroxymethylfurfural (HMF), proline, diastase index, apparent sucrose, total flavonoids content and total phenol content. On the other hand, the model was less accurate for pH determination. The calibration models had high r 2 (ranging between 92.8% and 99.9%), high residual prediction deviation - RPD (ranging between 4.2 and 26.8) and low root mean square errors. These results confirm the hypothesis that FT-Raman is a useful technique for the quality control and chemical properties’ evaluation of Lavandula spp honey. Its application may allow improving the efficiency, speed and cost of the current laboratory analysis.Acknowledgements: CEF is a research unit funded by Fundação para a Ciência e a Tecnologia I.P. (FCT), Portugal (UID/AGR/00239/2013). Centre of Molecular and Environmental Biology is a research unit funded by FCT, UID/BIA/04050/2013 (POCI-01–0145-FEDER-007569) and by the ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI).info:eu-repo/semantics/publishedVersio

Impact of the pulling rate on the redox state and magnetic domains of Fe-Si-O glass ceramic processed by LFZ method

This work studies the effect of the pulling rate, varying from 100 to 400 mm/h, on the redox state, structure and magnetic properties of iron oxide bearing silica glasses processed by laser floating zone (LFZ) method. XRD analysis revealed that the maximum crystallinity is obtained in the fibre grown at the lowest pulling rate. A detailed Raman analysis demonstrated that the global content of Fe2+ increases with pulling rate, while the growth under a lower pulling rate promotes the α-Fe2O3 crystallization. Atomic/magnetic force microscopy provided further evidence of phase-separated iron oxide crystallites formation with a high Fe2+/Ftotal ratio as the pulling rate increases. The magnetic measurements performed over a wide temperature range showed that the highest magnetization is found in the fibre grown at the highest pulling rate. A strong correlation between structural-topographical features and the magnetic characteristics of the glass fibres is substantiated.publishe

Naturaleza de la ciencia y educación científica para la participación ciudadana. Una revisión crítica

La didáctica de las ciencias promueve hoy la presencia explícita de la naturaleza de la ciencia en el currículo de ciencias, aportando diversos motivos para ello. Este artículo se ocupa del argumento democrático relacionado con la participación ciudadana en la toma de decisiones tecnocientíficas en la sociedad civil. Tras una breve exposición sobre la naturaleza de la ciencia desde el punto de vista de la didáctica de las ciencias, se subraya el papel esencial que en la enseñanza de las ciencias debería tener la educación para la participación en las decisiones tecnocientíficas, lo que permitiría dar sentido pleno a la finalidad educativa de la alfabetización científica y tecnológica para todas las personas. A partir de investigaciones procedentes de la propia didáctica de las ciencias, se revisa después la influencia de la comprensión de la naturaleza de la ciencia en las decisiones tecnocientíficas, concluyéndose que otros factores pueden afectar tanto o más que ella, lo que hace mucho más compleja la cuestión planteada. Por último, se reflexiona sobre la naturaleza de la ciencia y la educación científica.Palabras clave: naturaleza de la ciencia, educación científica, decisiones tecnocientíficas, participación ciudadana, movimiento CTS.Nature of science and scientific education for citizen participation. A critical reviewThe didactics of science today promotes the explicit presence of the nature of science in the science curriculum, providing various reasons for this. This article deals with the democratic argument related to citizen participation in the making of technoscientific decisions in civil society. After a brief presentation on the nature of science from the point of view of science didactics, the essential role that science education should play in participation in technoscientific decisions is emphasized. full meaning to the educational purpose of scientific and technological literacy for all people. Based on research from the science didactics itself, the influence of the understanding of the nature of science on technoscientific decisions is then reviewed, concluding that other factors can affect as much or more than it, which makes it much more complex the question raised. Finally, we reflect on the nature of science and scientific education.Keywords: nature of science, scientific education, technoscientific decisions, citizen participation, CTS movement

Multi-k⃗\vec{k} Configurations

Using resonant x-ray scattering to perform diffraction experiments at the U M$_{4}$ edge novel reflections of the generic form have been observed in UAs$_{0.8}$Se$_{0.2}$ where $\vec{k} = $, with $k = {1/2}$ reciprocal lattice units, is the wave vector of the primary (magnetic) order parameter. The reflections, with $10^{-4}$ of the magnetic intensities, cannot be explained on the basis of the primary order parameter within standard scattering theory. A full experimental characterisation of these reflections is presented including their energy, azimuthal and temperature dependencies. On this basis we establish that the reflections most likely arise from the electric dipole operator involving transitions between the core 3d and partially filled $5f$ states. The temperature dependence couples the peak to the triple-$\vec{k}$ region of the phase diagram: Below $\sim 50$ K, where previous studies have suggested a transition to a double-$\vec{k}$ state, the intensity of the $$ is dramatically reduced. Whilst we are unable to give a definite explanation of how these novel reflections appear, this paper concludes with a discussion of possible ideas for these reflections in terms of the coherent superposition of the 3 primary (magnetic) order parameters

Weak ferromagnetism with very large canting in a chiral lattice: (pyrimidine)2FeCl2

The transition metal coordination compound (pyrimidine)2FeCl2 crystallizes in a chiral lattice, space group I 4_1 2 2 (or I4_3 2 2). Combined magnetization, Mossbauer spectroscopy and powder neutron diffraction studies reveal that it is a canted antiferromagnet below T_N = 6.4 K with an unusually large canting of the magnetic moments of 14 deg. from their general antiferromagnetic alignment, one of the largest reported to date. This results in weak ferromagnetism with a ferromagnetic component of 1 mu_B. The large canting is due to the interplay between the antiferromagnetic exchange interaction and the local single-ion anisotropy in the chiral lattice. The magnetically ordered structure of (pyrimidine)2FeCl2, however, is not chiral. The implications of these findings for the search of molecule based materials exhibiting chiral magnetic ordering is discussed.Comment: 6 pages, 5 figure

3β,5α,6β-Trihy­droxy­androstan-17-one

The title compound, C19H30O4, is an androstan-17-one derivative synthesized from the dehydro­epiandrosterone through a sequential addition of an oxidant, followed by a trans-diaxial opening of the epoxide generated, with Bi(OTf)3 (OTf is trifluoro­methane­sulfonate). The six-membered rings have a slightly flattened chair conformation, while the five-membered ring adopts a 14-α envelope conformation. All rings are trans fused. In the crystal, the mol­ecules are connected by O—H⋯O hydrogen bonds involving the hydroxyl and carbonyl groups, forming a three-dimensional network. A quantum mechanical ab initio Roothan Hartree–Fock calculation of the free mol­ecule gives bond lengths, valency angles and ring torsion angles of the free molecule at equilibrium geometry (energy minimum) close to the experimental values

Octupolar ordering of Gamma8 ions in magnetic field

We study f-electron lattice models which are capable of supporting octupolar, as well dipolar and quadrupolar, order. Analyzing the properties of the Gamma8 ground state quartet, we find that (111)-type combinations of the Gamma5 octupoles Tbeta(111)=Tbeta(x)+Tbeta(y)+Tbeta(z) are the best candidates for octupolar order parameters. Octupolar ordering induces Gamma5-type quadrupoles as secondary order parameter. Octupolar order is to some extent assisted, but in its basic nature unchanged, by allowing for the presence of quadrupolar interactions. In the absence of an external magnetic field, equivalent results hold antiferro-octupolar ordering on the fcc lattice. In this sense, the choice of our model is motivated by the recent suggestion of octupolar ordering in NpO2. The bulk of our paper is devoted to a study of the effect of an external magnetic field on ferro-octupolar ordering. We found that octupolar order survives up to a critical magnetic field if the field is lying in specific directions, while for general field directions, the underlying symmetry of the model is destroyed and therefore the phase transition suppressed even in weak fields. Field-induced multipoles and field-induced couplings between various order parameters are discussed on the basis of a group theoretical analysis of the Helmholtz potential. We also studied the effect of octupolar ordering on the non-linear magnetic susceptibility which satisfies Ehrenfest-type relations at continuous octupolar transitions.Comment: 29 pages, 10 figures LaTeX In its contents, the present version agrees with the published one (see Journal Reference below). Essential additions to the text in Sec. III, otherwise some change of wording, and minor correction