Jane Marcet. Un modelo didáctico de la electroquímica en el S. XIX

En la siguiente comunicación se describe un estudio histórico didáctico sobre el libro Conversations on Chemistry de Jane Marcet en la Inglaterra del S XIX. Este libro de divulgación científica tuvo gran importancia en el ámbito educativo en particular para la audiencia femenina. Los resultados del análisis realizado, permiten concluir que el libro se caracteriza por poseer un modelo de ciencia problemática, la narrativa es de duda retórica; el modelo de lector es aprendiz activo y el modelo de aula es constructivista. A pesar de existir gran controversia por el uso de las diferentes ediciones, según el público destinatario

Concepciones de los profesores de química sobre naturaleza de la ciencia e historia de la ciencia

En la siguiente comunicación se describen las concepciones acerca de la Naturaleza de la Ciencia e Historia de la Ciencia, encontradas en el profesorado de química participante en un estudio del Proyecto FONDECYT 1070795. Los resultados permiten concluir que los profesores de la región metropolitana de Santiago de Chile, destacan los aportes que pueden hacer la Naturaleza de la Ciencia a la comprensión conceptual y la Historia de la Ciencia a la comprensión contextual del conocimiento científico. Sin embargo, también señalan como alguna deficiencias la formación débil en estas áreas científicas, los programas curriculares y las temáticas químicas

Synthesis and complementary self-association of novel lipophilic π-conjugated nucleoside oligomers

The following article appeared in Organic and Biomolecular Chemistry 13.15 (2015): 4506-4513 and may be found at http://dx.doi.org/10.1039/c5ob00098j, reproduced by permission of The Royal Society of ChemistryA series of lipophilic nucleosides comprising natural and non-natural bases that are π-conjugated to a short oligophenylene-ethynylene fragment has been synthesized. These bases comprise guanosine, isoguanosine, and 2-aminoadenosine as purine heterocycles, and cytidine, isocytosine and uridine as complementary pyrimidine bases. The hydrogen-bonding dimerization and association processes between complementary bases were also studied by 1H NMR and absorption spectroscopy in order to obtain the relevant association constantsFunding from the European Research Council (ERC-StG 279548) and MINECO (CTQ2011-23659) is gratefully acknowledge

El gasto sanitario en España en comparación con el de la Europa desarrollada, 1985–2001. La atención primaria española, Cenicienta europea

ObjetivoDescribir la evolución de la distribución de fondos en nuestro sistema sanitario desde el inicio de la reforma de atención primaria hasta 2001, en comparación con la de los países europeos de la Organización para la Cooperación y el Desarrollo Económico (OCDE)DiseñoEstudio descriptivo longitudinal y retrospectivoEmplazamientoPaíses de la OCDEParticipantesPaíses europeos de la OCDEMedicionesSe utilizan datos de la base Health Data 2003 (OCDE) referidos al período 1985–2001 respecto a variables de gasto sanitario por sectores y de renta. Se comparan los datos españoles con los del conjunto de los 22 países europeos de la OCDEResultadosEuropa aumentó el gasto ambulatorio público, tanto como porcentaje del gasto sanitario público como del producto interior bruto (PIB). España redujo el gasto ambulatorio público en ambos sentidos. Nuestro gasto hospitalario público recuperó gran parte del retraso respecto a Europa y desde 1995 se encuentra, como parte del PIB, en la media europea y, en términos per cápita, acorde con nuestra renta. Sin embargo, nuestro gasto ambulatorio público como parte del PIB es muy inferior al promedio europeo y, per capita, muy inferior a nuestra renta. Nuestro gasto ambulatorio privado es de los más altos de Europa y, en relación con ella, muy superior a nuestra renta, al contrario que su homónimo público. Nuestro gasto privado hospitalario es de los más bajos de Europa y, en relación con ella, muy inferior a nuestra rentaConclusionesRespecto a los recursos públicos comprometidos, la reforma de la atención primaria española no ha servido para aproximarla a Europa, tal y como sí lo ha hecho nuestro nivel hospitalario. La distancia entre España y Europa en el esfuerzo público ambulatorio es incluso mayor que la que había al inicio de la reformaObjetiveTo describe the evolution of the funds distribution in our health care system since the start of the primary care reform to 2001, in comparison with the European countries members of the Organisation for Economic Co-operation andDevelopment (OECD)DesignA longitudinal descriptive and retrospective studyParticipantsEuropean countries members of the OECDSettingCountries members of the OECDMethodsThe data come from the OECD database Health Data 2003. The data refer to period 1985–2001, and to a group of variables of health care expenditure by sectors and of income (Gross Domestic Product [GDP] per capita). We compare Spanish data series with those of the group of 22 European members countries of the OECDResultsEurope increased public expenditure on outpatient care both as a percentage of public health care expenditure and as a percentage of GDP. Spain reduced public expenditure on outpatient care in both senses. Spanish publicexpenditure on in-patient care reduced a great partof its difference with Europe so that since 1995 it isfound, as a percentage of GDP, in the Europeanaverage and, as per capita, it is according with theSpanish income. In contrast, public expenditure onout-patient care as a percentage of GDP in Spain isvery much lower than the European average and, asper capita, is very much lower than the Spanishincome. The Spanish private expenditure on outpatient is found among the highest in Europe and, compared with Europe, exceeds very much Spanish income, in contrast with his homonymous public. The Spanish private expenditure on in-patient care is found among the lowest in Europe and, compared with Europe, is very much lower than Spanish income levelConclusionsWith respect to public resources assigned, the reform of primary care in Spain has not been useful to approach Spanish primary health care level to Europe, in contrast with the Spanish hospital level. The difference between Spain and Europe in public expenditure on out-patient care as a percentage of GDP is, even, bigger than the one there was when the reform of Spanish primary care starte

A modified Nukiyama-Tanasawa distribution function and a Rosin-Rammler model for the particle-size-distribution analysis

Abstract No fundamental mechanism or model enables a theory on particle-size distribution to be built. Consequently, a wide variety of empirical models or equations have been proposed to characterize experimental particle-size distributions, such as the Rosin-Rammler model. Because the Nukiyama-Tanasawa equation uses four parameters to simulate differential distribution frequencies for particle-size diameters, the distribution function is not easy to apply in order to fit experimental data. In this paper, a modification of the Nukiyama-Tanasawa model with only two parameters has been proposed to fit the data on a particle-size distribution (PSD). The proposed normalized distribution function has been applied successfully to the PSD analysis (cork granulate and spray atomization droplets)

Drag reduction on a blunt body by self-adaption of rear flexibly hinged flaps

We study the aerodynamics of a blunt-based body with rear flexibly-hinged rigid flaps, subject to a turbulent flow of Reynolds number Re = 12000, under aligned and cross flow conditions with yaw angle β = 0◦ and β = 4◦. To that aim, different values of the equivalent torsional stiffness are considered, to cover the range of reduced velocity U∗ = (0, 3.48] in water tank experiments. The effect of the angular deflection of plates on the drag and near wake flow is analyzed, experimentally and numerically. The results show that, in the range of U∗ herein considered, the plates undergo an inwards quasi-static, self-adaptive deflection, which is symmetric for yaw angles β = 0◦ and asymmetric for β = 4◦. In particular, the plates feature small mean deformation angles for values of U∗ < 1, whereas a sharp and monotonic increase of such deflection occurs for U∗ > 1, i.e. for lower values of the hinge’s stiffness, with an asymptotic trend towards the larger values of U∗. A critical value of reduced velocity of U∗ ≃ 0.96 is obtained as the instability threshold above which plates depart from their initial equilibrium position. The progressive streamlining of the trailing edge translates into significant reductions of the associated mean drag coefficients. Thus, reductions close to 19% with respect to reference static plates configurations are obtained for the most flexible case of U∗ = 3.48 for both β = 0◦ and β = 4◦. A close inspection of the near wake reveals that the inwards progressive mean displacement of the plates yields a reduction in the recirculation bubble size. A symmetric evolution of the recirculating bubble is observed for β = 0◦, whereas the bubble becomes asymmetric for β = 4◦, with a larger leeward clockwise vortex. In both cases, the drag coefficient is shown to vary linearly with the global aspect ratio of the recirculating bubble. The analysis of the numerical results shows that the reduced extension of the recirculating bubble significantly alters the formation length and intensity of the eddies size and associated pressure. It is observed that despite the local pressure decrease in the vortices shed from the trailing edges, the plates self adaption reduces their size and prevents the eddies from entering the cavity, thus, creating a dead flow region with a consequent pressure increase at the body base.Junta de Andalucia FEDER-UJA 1262764Universidad de JaenEuropean CommissionSpanish MCIN/AEI PDC2021-121288-I00European Union Next Generation EU/PRT

Raman spectroscopy and photoluminescence of ZnTe thin films grown on GaAs

We report resonant Raman scattering and photoluminescence (PL) measurements on two ZnTe thin films grown by molecular-beam epitaxy on GaAs substrates with thicknesses around 0.5 and 1.0 μm. The data have been obtained by using the different excitation energies of an Ar+ laser to distinguish Raman from PL and analyze resonant effects. The characteristic features of the low-temperature PL spectra are the light and heavy free exciton emissions, split due to the thermal strain effect, followed by several phonon replicas of these lines. Moreover, longitudinal and transversal polariton splittings of heavy excitons are clearly observed. Their reduced masses have been obtained from the exciton binding energies. Room and low-temperature Raman spectra show, besides the typical longitudinal optical (LO) multiphonon emissions, forbidden zone-center transverse optical (TO)+(n−1)LO phonon combinations, which yield an accurate value for the LO and TO phonon energies. The breakdown of the selection rules is attributed to surface [email protected] ; [email protected]

Dye-conjugated complementary lipophilic nucleosides as useful probes to study association processes by fluorescence resonance energy transfer

Modern supramolecular chemistry relies on the combination of diverse analytical techniques that can provide complementary information on complex self-assembly landscapes. Among them, resonance energy transfer, monitored by fluorescence emission spectroscopy, arises as a sensitive and convenient phenomenon to report binding intermolecular interactions. The use of molecular probes labelled with suitable complementary energy-transfer pairs can provide valuable information about the thermodynamics, kinetics and self-sorting characteristics of a particular self-assembled system. The objective of this work is to generate a set of nucleoside FRET probes that can be reliably employed to prove and analyse quantitatively H-bonding interactions between complementary Watson-Crick pairs. We first describe the preparation of a set of lipophilic nucleosides that are linked to a π-conjugated functional fragment. The bases include guanosine and 2-aminoadenosine as purine heterocycles, and cytidine and uridine as complementary pyrimidine bases. The π-conjugated moiety comprises either a short phenylene-ethynylene oligomer, a bithiophene, or a BODIPY dye. We then demonstrate that the last two chromophores constitute an energy donor-acceptor couple and that donor emission quenching can be related to the ratio of molecules bound to the complementary acceptor pair. Hence, fluorescence spectroscopy in combination with resonance energy transfer, is shown here to be a useful tool to study and quantify the association and self-sorting events between complementary and non-complementary nucleosides in apolar aromatic solvents, where the binding strength is considerably high, and sensitive techniques that employ low concentrations are demandedFunding from the European Research Council (ERC-Starting Grant 279548 PROGRAM-NANO) and MINECO (CTQ2014-57729-P) is gratefully acknowledged. E. F. would like to thank the Sharif University of Technology of Iran for financial support. D. S.M. would like to acknowledge Comunidad de Madrid for financial support through contract PEJ16/IND/AI-084

Reversible collapse of insoluble monolayers

II Encuentro sobre nanociencia y nanotecnología de investigadores y tecnólogos de la Universidad de Córdoba. NANOUC