Flexible and low-cost binderless capacitors based on p- and n-containing fibrous activated carbons from denim cloth wastes

Activated carbon cloths have been prepared from denim cloth wastes (DCWs) through chemical activation with H3PO4. The effect of the H3PO4/DCWs impregnation ratio and the carbonization temperature on the porous texture, the chemical composition, the fibers morphology, and the electrochemical performance has been studied. Low H3PO4/DCWs impregnation ratios lead to flexible and microporous activated carbons cloths, whereas more fragile and rigid activated carbon cloths with higher external surface area are produced upon increasing the amount of H3PO4. The increase in the carbonization temperature allows for obtaining a more ordered and conductive carbon structure. The activated carbon prepared at 900 ºC with a H3PO4/DCWs impregnation ratio of 0.5 (w/w) exhibits the best performance as electric double layer capacitor. This electrode shows a specific surface area of 2016 m2 g-1 and the highest registered gravimetric capacitance (227 F g-1). Moreover, its flexibility minimizes the ohmic resistance of the electrode, thus increasing the feasibility of working at higher current densities than the other synthesized electrodes.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech; MINECO CTQ2015-68654-

Caring for Sexuality and Reproduction: Experiencing community based care and state-run health care in a Ngöbe indigenous community in Costa Rica

The Ngöbe are an indigenous group that resides in the north of Panama and the south Pacific region of Costa Rica. This thesis uses the ethnographic method to examine indigenous Ngöbe women’s practices and experiences of sexual and reproductive health care in a rural community in the southern region of Costa Rica. Indigenous Ngöbe women from El Bajo seek social and medical care practices provided by the community and the state-run health care facility. In their search for well-being, health care seekers consider diverse possibilities within their kin relationships, the community resources, and the state-run health care facility. This thesis also analyses the practices of health care professionals and the subjectivities associated with their work as well as the policies and discourses impacting the state-run sexual and reproductive health care actions, which influences the process of receiving/providing care. This thesis treats care as a practice that is informed by the logics of relationality and individuality. These logics are located in what Bourdieu terms habitus and as such are related to action and not to conscious reasoning. These logics highlight the individual’s relationship to their kin, their community and the environment, as well as the individual’s autonomy in relation to society and nature. These logics inform the practices of both health care professionals and Ngöbe indigenous women and, as a result, the two groups display different combinations of these logics which exist in the form of a spectrum. The actors’ positionalities play a role in shaping the logics within the structure in terms of gender, ethnicity, class, geographic location, and access to biomedical knowledge. Thus, the logics of relationality and individuality are combined in multiple ways; and in the process of exercising their agency people navigate the spectrum according to their possibilities ―social, economic, etc.― based on their positionality within the structure. This thesis follows a comprehensive understanding of women’s exercise of agency through resistance, the inhabiting of norms, and connection and belonging. Consequently, the main focus here is on the Ngöbe women of this community and their experiences and practices of sexual and reproductive health care

IMPROVED SOUND SPEED CONTROL THROUGH REMOTELY DETECTING STRONG CHANGES IN THE THERMOCLINE

Internal waves are a common phenomenon associated with stratification developed in shallow tidal seas during summer time. From a hydrographic point of view, they result in very rapid undulations in the main velocline which, if not accounted for, will result in significant refraction errors in multibeam echo sounder data. Mechanical sound speed profiling, both static and mobile, cannot sample this structure adequately (Hughes Clarke, 2017). Thus, an alternate means of detecting and accounting for that variability is needed. Within the oceanographic community, it has long been recognized that a distinct acoustic volume scattering layer is often associated within or close to major oceanographic boundaries. This has been noted to reflect a combination of temperature/salinity microstructure and zooplankton around the pycnocline depth. Several weeks of multibeam survey on the Irish continental shelf were undertaken during which multispectral acoustic scattering data from a Simrad EK60 scientific echo sounder were acquired together with profiles from a Moving Vessel Profiler. This thesis proposes and implements a method to determine the evolving sound speed structure by processing the images derived from the EK60 echo sounder. This is done by extracting the scattering layer depth and finding the correlations with the velocline found in each of the discrete MVP profiles. Thus, a continuously evolving estimate of the local sound speed structure is derived. From this, by calculating the associated depth bias in the seafloor modeling caused by the difference in sound speed structure between the last actual profile and the estimate at each ping, a visual indication of the need for a new in situ measurement is made. In this manner, the sound speed structure may be monitored to adjust the spatial and temporal resolutions of the profile casts more efficiently

Competition between Polar and Antiferrodistortive Modes and Correlated Dynamics of the Methylammonium Molecules in MAPbI3_3 from Anelastic and Dielectric Measurements

The mechanisms behind the exceptional photovoltaic properties of the metallorganic perovskites are still debated, and include a ferroelectric (FE) state from the ordering of the electric dipoles of the organic molecules. We present the first anelastic (complex Young's modulus) and new dielectric measurements on CH$_{3}$NH$_{3}$PbI$_3$, which provide new insight on the reorientation dynamics of the organic molecules, and the reason why they do not form a FE state. The permittivity is fitted within the tetragonal phase with an expression that includes the coupling between FE and octahedral tilt modes, indicating that the coupling is competitive and prevents FE ordering. The onset of the orthorhombic phase is accompanied by sharp stiffening, analogous to the drop of permittivity, due to the hindered molecular dynamics. On further cooling, an intense anelastic relaxation process without a dielectric counterpart suggests the reorientation of clusters of molecules with strong antiferroelectric correlations.Comment: accepted in J. Phys. Chem. Let

Thalassorama: Marketing Extension and Outreach in Sinaloa, Mexico: A Preliminary Analysis of Preferences for Oysters

Marketing, oyster preferences, Mexico, Agribusiness, Agricultural and Food Policy, Consumer/Household Economics, Crop Production/Industries, International Development, International Relations/Trade, Research Methods/ Statistical Methods, Teaching/Communication/Extension/Profession, M30, M39,

Stability of Cubic FAPbI3_3 from X-ray Diffraction, Anelastic, and Dielectric Measurements

Among the hybrid metal-organic perovskites for photovoltaic applications FAPbI_3 (FAPI) has the best performance regarding efficiency and the worst regarding stability, even though the reports on its stability are highly contradictory. In particular, since at room temperature the cubic alpha phase, black and with high photovoltaic efficiency, is metastable against the yellow hexagonal delta phase, it is believed that alpha-FAPI spontaneously transform into delta-FAPI within a relatively short time. We performed X-ray diffraction and thermogravimetric measurements on loose powder of FAPI, and present the first complete dielectric and anelastic spectra of compacted FAPI samples under various conditions. We found that alpha-FAPI is perfectly stable for at least 100 days, the duration of the experiments, unless extrinsic factors induce its degradation. In our tests, degradation was detected after exposure to humidity, strongly accelerated by grain boundaries and the presence of delta phase, but it was not noticeable on the loose powder kept in air under normal laboratory illumination. These findings have strong implications on the strategies for improving the stability of FAPI without diminishing its photovoltaic efficiency through modifications of its composition

Detailed Abundances for a Large Sample of Giant Stars in the Globular Cluster 47 Tucanae (NGC 104)

47 Tuc is an ideal target to study chemical evolution and GC formation in massive more metal-rich GCs since is the closest, massive GC. We present chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu in 164 red giant branch (RGB) stars in the massive globular cluster 47 Tuc using spectra obtained with both the Hydra multi-fiber spectrograph at the Blanco 4-m telescope and the FLAMES multi-object spectrograph at the Very Large Telescope. We find an average [Fe/H]=--0.79$\pm$0.09 dex, consistent with literature values, as well as over-abundances of alpha-elements ([\alpha/\mbox{Fe}]\sim0.3 dex). The n-capture process elements indicate that 47 Tuc is r-process dominated ([Eu/La]=+0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anti-correlation, a signature typically seen in Galactic globular clusters, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] $\sim$\,--0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A KS-test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of AGB nucleosynthesis yields.Comment: Accepted for publication in The Astrophysical Journa

Synthesis and characterization of a new nanosorbent based on functionalized magnetic nanoparticles and its use in the determination of mercury by FI-CV-ETAAS

In this work, a new chelating sorbent which employs 1,5-bis(di-2-pyridil)methylene thiocarbohydrazide as the functional group and magnetic nanoparticles (MNPs) as its support (DPTH-MNP) was synthetized and characterized. The MNPs were prepared by coprecipitation of Fe+2 and Fe+3 with NH3 and then coated with silica in order to easily bind the support and the functionalizing molecule. The aim of the synthesis of this material is applying it as a solid-phase extracting agent and evaluating its potential for the extraction and pre-concentration of trace amounts of analytes present in biological and environmental samples with on-line methods. The MNPs’ magnetic core would allow overcoming the usual backpressure problems that happen in solid-phase extraction methods thanks to the possibility of immobilizing the MNPs by applying an external magnetic field. From the study of its adsorption capacity toward metal ions, mercury and antimony were the most retained. Thus, a flow injection solid phase extraction and cold vapor generation method for mercury determination based on the use of this new chelating nanosorbent was optimized. The greatest efforts were put into the reactor design to minimize compaction and loss of nanosorbent. The knotted reactor shown in Figure 1 was chosen as the best. Then, chemical and flow variables were optimized by Central composite designs (CCDs). The method developed has showed to be useful for the automatic pre-concentration and determination of mercury in environmental and biological samples. The determination was performed using electrothermal atomic absorption spectrometry (ETAAS). Under the optimum conditions, pH 5 and 120 s preconcentration time, the enrichment factor was 5.33; the detection limit (3σ) was 7.8 ng L-1; the determination limit (10σ) was 99 ng L-1; and the precisions (calculated for 10 replicate determinations at a 1 and 5 µg L-1 standards) were 1.7 and 1.9 % (RSD), respectively. Two linear calibration graphs were obtained, from the determination limits to 10 µg L-1 and from 10 to at least 50 µg L-1. From the comparison with other similar methods found in the bibliography, the detection limit and precisions calculated with our method were better. In order to evaluate the accurate and applicability of the method, the analysis of five certified samples LGC 6016 estuarine water, TMDA 54.4 fortified lake water, SRM 2976 mussel tissue, TORT-1 lobster hepatopancreas and DOLT-1 dogfish liver by standard addition and external calibration, were addressed. The results showed good agreement between the certified values, or added amounts of mercury, and the found concentrations. The method was successfully applied to the determination of mercury in sea-water samples collected in the Málaga Bay.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec