Recent progress in the synthesis of nanostructured magnesium hydroxide

This review highlights synthetic routes for producing nanostructured magnesium hydroxide and focuses on how these various preparative approaches can produce Mg(OH)2 nanoparticles with controlled size and morphology. Mg(OH)2 nanocrystals with rod-, needle-, hollow tube- or platelet-like morphology can be synthesised by the modification of chemical and physical experimental parameters such as the selection of magnesium precursor, solvent and temperature or by employing surface modifiers and templates. Techniques based on hydrothermal/solvothermal treatments, microwave heating and (co-)precipitation are dominant in the production of Mg(OH)2 at the nanoscale, but other materials design approaches are now emerging. Bulk Mg(OH)2 has been extensively studied over decades and finds use in a wide range of applications. Moreover, the hydroxide can also serve as a precursor for other commercially important materials such as MgO. Nanostructuring the material has proven extremely useful in modifying some of its most important properties – not least enhancing the performance of Mg(OH)2 as a non-toxic flame retardant – but equally it is creating new avenues of applied research. We evaluate herein the latest efforts to design novel synthesis routes to nano-Mg(OH)2, to understand the mechanisms of crystallite growth and to tailor microstructure towards specific properties and applications

Ammonia borane-based nanocomposites as solid state hydrogen stores for portable power applications

Ammonia borane (AB) based nanocomposites have been investigated with the aim of developing a promising solid-state hydrogen store that complies with the requirements of a modular polymer electrolyte membrane fuel cell (PEM FC) in a portable power pack system. AB-carbon nanocomposites (prepared via ball milling or solution-impregnation) demonstrate improved hydrogen release performance compared to AB itself in terms of onset temperature and hydrogen purity, while maintaining a gravimetric density of more than 5 wt. % H2. The most promising of these materials is an AB-AC (activated carbon) composite, synthesised via solution-impregnation with an optimal dehydrogenation temperature of 96 °C. When combined with an external nickel chloride filter downstream, no evolved gaseous by-products can be detected above 100 ppb. The feasibility of an AB-AC storage tank has been further endorsed by simulations in which the reaction rate and the hydrogen flux was found to be almost constant as the temperature front propagated from the bottom to the top of the tank after initiation

Rapid surfactant-free synthesis of Mg(OH)2 nanoplates and pseudomorphic dehydration to MgO

Magnesium hydroxide nanoplates ca. 50 nm in thickness can be prepared over minute timescales via hydrothermal synthesis in a multimode cavity (MMC) microwave reactor. This approach allows ca. 1 g of single-phase Mg(OH)2 to be synthesised in under 3 minutes without the requirement of surfactants or non-aqueous solvents. The hydroxide nanomaterial dehydrates at temperatures >200 K below that of the equivalent bulk material and can be utilised as a precursor for the pseudomorphic synthesis of nanoplates of MgO as investigated by TG-DTA-MS, XRD and SEM measurements. Equally, the pseudomorphic synthesis can be performed by irradiating the Mg(OH)2 nanomaterial with microwaves for 6 minutes to produce single phase MgO

Rapid surfactant-free synthesis of Mg(OH)2 nanoplates and pseudomorphic dehydration to MgO

Magnesium hydroxide nanoplates ca. 50 nm in thickness can be prepared over minute timescales via hydrothermal synthesis in a multimode cavity (MMC) microwave reactor. This approach allows ca. 1 g of single-phase Mg(OH)2 to be synthesised in under 3 minutes without the requirement of surfactants or non-aqueous solvents. The hydroxide nanomaterial dehydrates at temperatures >200 K below that of the equivalent bulk material and can be utilised as a precursor for the pseudomorphic synthesis of nanoplates of MgO as investigated by TG-DTA-MS, XRD and SEM measurements. Equally, the pseudomorphic synthesis can be performed by irradiating the MgIJOH)2 nanomaterial with microwaves for 6 minutes to produce single-phase MgO.JRC.F.2-Energy Conversion and Storage Technologie

Anxiety and depression in association with lower urinary tract symptoms: results from the COBaLT study

La depresión y la ansiedad se han asociado con síntomas del tracto urinario inferior (STUI) en varios estudios. En nuestra población la prevalencia de STUI es alta, por lo que es fundamental y objetivo de este estudio determinar la asociación entre ansiedad, depresión y STUI en una gran población hispana. Métodos Se realizó un subanálisis de un estudio poblacional transversal para estimar la prevalencia de STUI en la población colombiana (estudio COBaLT) (Plata et al. en Neurourol Urodyn 38:200–207, 2018). Para evaluar la salud mental se utilizó la Escala Hospitalaria de Ansiedad y Depresión (HADS). Se llevó a cabo una regresión logística para estimar la asociación de la depresión y la ansiedad con diferentes STUI. Las variables que resultaron estadísticamente significativas ( p  < 0,05) se incluyeron en un modelo multivariado. Resultados Se evaluaron un total de 1060 personas. La prevalencia de ansiedad en mujeres y hombres fue del 17,1% y 6,7%, respectivamente. La depresión en mujeres y hombres fue del 20,1% y 9,4%, respectivamente. Se encontró asociación entre ansiedad y vejiga hiperactiva (VH) sin incontinencia urinaria (OR = 3,7) y STUI moderados o graves en hombres (OR = 3,8). En las mujeres, la ansiedad se asoció con nicturia (OR = 4,2) e incontinencia urinaria de esfuerzo (OR = 2,4). Para la depresión, se encontró una asociación entre disfunción sexual (OR = 4,3) y STUI moderados o graves (OR = 4,0) en hombres; mientras que en las mujeres se asoció con la incontinencia urinaria de esfuerzo (OR = 2,3), la sensación de vaciado incompleto (OR = 1,7) y la disminución de la frecuencia de la actividad sexual (OR = 1,8). Conclusiones Las asociaciones encontradas son consistentes con otros informes. Es fundamental indagar sobre posibles síntomas relacionados con la esfera mental en la consulta de urología para realizar las derivaciones adecuadas y el manejo posterior.Q1Q1Depression and anxiety have been associated with lower urinary tract symptoms (LUTS) in several studies. In our population, the prevalence of LUTS is high, consequently, it is essential and an objective of this study, to determine the association between anxiety, depression, and LUTS in a large Hispanic population. Methods A sub-analysis of a cross‐sectional population‐based study to estimate LUTS prevalence in the Colombian population was performed (COBaLT study) (Plata et al. in Neurourol Urodyn 38:200–207, 2018). The Hospital Anxiety and Depression Scale (HADS) was used to evaluate mental health. Logistic regression was carried out to estimate the association of depression and anxiety with different LUTS. Variables that proved statistically significant (p < 0.05) were included in a multivariate model. Results A total of 1060 individuals were assessed. The prevalence of anxiety in women and men was 17.1% and 6.7%, respectively. Depression in women and men was 20.1% and 9.4%, respectively. An association was found between anxiety and overactive bladder (OAB) without urinary incontinence (OR = 3.7) and moderate or severe LUTS in men (OR = 3.8). In women, anxiety was associated with nocturia (OR = 4.2) and stress urinary incontinence (OR = 2.4). For depression, an association was found between sexual dysfunction (OR = 4.3) and moderate or severe LUTS (OR = 4.0) in men; while in women it was associated with stress urinary incontinence (OR = 2.3), the sensation of incomplete emptying (OR = 1.7) and decreased frequency of sexual activity (OR = 1.8). Conclusions The associations found are consistent with other reports. It is essential to inquire about possible symptoms related to the mental sphere in the urology consultation to make appropriate referrals and subsequent management.Revista Internacional - IndexadaS

Associated factors for mortality in a COVID-19 colombian cohort : is the third wave relevant when Mu variant was predominant epidemiologically?

Q1Q1Pacientes con COVID-19Objectives: To evaluate the association between Colombia's third wave when the Mu variant was predominant epidemiologically (until 75%) in Colombia and COVID-19 all-cause in-hospital mortality. Methods: In this retrospective cohort, we included hospitalized patients ≥18 years with SARS-CoV-2 infection between March 2020 to September 2021 in ten hospitals from three cities in Colombia. Description analysis, survival, and multivariate Cox regression analyses were performed to evaluate the association between the third epidemic wave and in-hospital mortality. Results: A total of 25,371 patients were included. The age-stratified time-to-mortality curves showed differences according to epidemic waves in patients ≥75 years (log-rank test p = 0.012). In the multivariate Cox analysis, the third wave was not associated with increased mortality relative to the first wave (aHR 0.95; 95%CI 0.84–1.08), but there was an interaction between age ≥75 years and the third wave finding a lower HR for mortality (aHR 0.56, 95%CI 0.36–0.86). Conclusions: We did not find an increase in in-hospital mortality during the third epidemic wave in which the Mu variant was predominant in Colombia. The reduced hazard in mortality in patients ≥75 years hospitalized in the third wave could be explained by the high coverage of SARS-CoV-2 vaccination in this population and patients with underlying conditions.https://orcid.org/0000-0003-1833-1599https://orcid.org/0000-0001-5363-5729https://orcid.org/0000-0001-6964-2229https://orcid.org/0000-0003-3975-2835https://orcid.org/0000-0001-9441-4375Revista Internacional - IndexadaA1N

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO