Two-Dimensional and Emission-Tunable: An Unusual Perovskite Constructed from Lindqvist-Type [Pb6Br19]7- Nanoclusters.

Preparing low-dimensional perovskite materials with novel building units is highly desirable because such materials have already been demonstrated to show unusual physical properties. In this report, we first reported a new and unusual two-dimensional perovskite framework, [B(HIm)4]4Pb13Br38 (1), constructed from novel Lindqvist-type [Pb6Br19]7- nanoclusters. The as-prepared material shows good water resistance and chemical/heat stability. More importantly, 1 has been proven to exhibit temperature/excitation-wavelength-dependent emission. A possible mechanism has been provided.

A 3D Haloplumbate Framework Constructed From Unprecedented Lindqvist-like Highly Coordinated [Pb6 Br25 ]13- Nanoclusters with Temperature-Dependent Emission.

Searching novel haloplumbate building units to construct three-dimensional (3D) frameworks is very important and highly desirable because such materials would possess new physical properties and potential applications. Here, by employing tetrakis(N-imidazolemethylene)methane(TIMM) as a structure-directing agent, the first 3D haloplumbate framework constructed from unprecedented Lindqvist-like highly coordinated [Pb6 Br25 ]13- nanoclusters has been successfully prepared under hydrothermal condition, where all Pb2+ centres in [Pb6 Br25 ]13- nanoclusters adopt seven-/eight-coordinated configurations. The as-obtained material is a wide-gap semiconductor (≈3.1 eV) and can be stable up to 320 °C. More importantly, this material has been demonstrated to show temperature-dependent emission. Our results could provide a new strategy to explore novel metal-halide open-framework materials.

Study of the exceptional meteorological conditions, trace gases and particulate matter measured during the 2017 forest fire in Doñana Natural Park, Spain.

In late June 2017, a forest fire occurred in Doñana Natural Park, which is located in southwestern Europe. Many animal and plant species, some of which are threatened, suffered from the impact of this fire, and important ecosystems in the European Union were seriously affected. This forest fire occurred under exceptional weather conditions. The meteorological situation was studied at both the synoptic scale and the local scale using meteorological fields in the ERA-Interim global model from ECMWF (European Centre for Medium Range Weather Forecasts), the WRF (Weather Research and Forecasting) mesoscale model and ground observations collected at El Arenosillo observatory. Anomalies were obtained using records (observations and simulations) over the last two decades (1996-2016). An anticyclonic system dominated the synoptic meteorological conditions, but a strong pressure gradient was present; positive high pressure anomalies and negative low pressure anomalies resulted in intense NW flows. At the surface, wind gusts of 80 km h-1, temperatures up to 35 °C and relative humidity values <20% were observed. In terms of anomalies, these observations corresponded to positive temperature anomalies (differences of 12 °C), positive wind speed anomalies (>29 km h-1) and negative relative humidity anomalies (differences of 40%). The forest fire reached El Arenosillo observatory approximately 8 h after it began. When the fire started, record-setting maximum values were measured for all gases monitored at this site (specifically, peaks of 99,995 µg m-3 for CO, 951 µg m-3 for O3, 478 µg m-3 for NO2, 116 µg m-3 for SO2 and 1000 µg m-3 for PM10). According to the temporal evolution patterns of these species, the atmosphere over a burnt area can recover to initial atmospheric levels between 48 and 96 h after an event. The impact of the Doñana plume was studied using hourly forward trajectories computed with the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model to analyse the emission source for the burnt area. The Doñana fire plume affected large metropolitan areas near the Mediterranean coast. Air quality stations located in the cities of Seville and Cadiz registered the arrival of the plume based on increases in CO and PM10. Using CO as a tracer, measurements from the AIRS and MOPITT instruments allowed us to observe the transport of the Doñana plume from the Strait of Gibraltar to the Mediterranean. Finally, after two days, the Doñana forest fire plume reached the western Mediterranean basin.

Spatial and temporal variability of carbonaceous aerosols: Assessing the impact of biomass burning in the urban environment.

Biomass burning (BB) is a significant source of atmospheric particles in many parts of the world. Whereas many studies have demonstrated the importance of BB emissions in central and northern Europe, especially in rural areas, its impact in urban air quality of southern European countries has been sparsely investigated. In this study, highly time resolved multi-wavelength absorption coefficients together with levoglucosan (BB tracer) mass concentrations were combined to apportion carbonaceous aerosol sources. The Aethalometer model takes advantage of the different spectral behavior of BB and fossil fuel (FF) combustion aerosols. The model was found to be more sensitive to the assumed value of the aerosol Ångström exponent (AAE) for FF (AAEff) than to the AAE for BB (AAEbb). As result of various sensitivity tests the model was optimized with AAEff=1.1 and AAEbb=2. The Aethalometer model and levoglucosan tracer estimates were in good agreement. The Aethalometer model was further applied to data from three sites in Granada urban area to evaluate the spatial variation of CMff and CMbb (carbonaceous matter from FF or BB origin, respectively) concentrations within the city. The results showed that CMbb was lower in the city centre while it has an unexpected profound impact on the CM levels measured in the suburbs (about 40%). Analysis of BB tracers with respect to wind speed suggested that BB was dominated by sources outside the city, to the west in a rural area. Distinguishing whether it corresponds to agricultural waste burning or with biomass burning for domestic heating was not possible. This study also shows that although traffic restrictions measures contribute to reduce carbonaceous concentrations, the extent of the reduction is very local. Other sources such as BB, which can contribute to CM as much as traffic emissions, should be targeted to reduce air pollution.

Value and Anisotropy of the Electron and Hole Mass in Pure Wurtzite InP Nanowires.

The effective mass of electrons and holes in semiconductors is pivotal in determining the dynamics of carriers and their confinement energy in nanostructured materials. Surprisingly, this quantity is still unknown in wurtzite (WZ) nanowires (NWs) made of III-V compounds (e.g., GaAs, InAs, GaP, InP), where the WZ phase has no bulk counterpart. Here, we investigate the magneto-optical properties of InP WZ NWs grown by selective-area epitaxy that provides perfectly ordered NWs featuring high-crystalline quality. The combined analysis of the energy of free exciton states and impurity levels under magnetic field (B up to 29 T) allows us to disentangle the dynamics of oppositely charged carriers from the Coulomb interaction and thus to determine the values of the electron and hole effective mass. By application of B⃗ along different crystallographic directions, we also assess the dependence of the transport properties with respect to the NW growth axis (namely, the WZ c axis). The effective mass of electrons along c is me∥ = (0.078 ± 0.002) m0 (m0 is the electron mass in vacuum) and perpendicular to c is me⊥ = (0.093 ± 0.001) m0, resulting in a 20% mass anisotropy. Holes exhibit a much larger (∼320%) and opposite mass anisotropy with their effective mass along and perpendicular to c equal to mh∥ = (0.81 ± 0.18) m0 and mh⊥ = (0.250 ± 0.016) m0, respectively. While no full consensus is found with current theoretical results on WZ InP, our findings show trends remarkably similar to the experimental data available in WZ bulk materials, such as InN, GaN, and ZnO.

Optical Investigation of Monolayer and Bulk Tungsten Diselenide (WSe2) in High Magnetic Fields.

Optical spectroscopy in high magnetic fields B ≤ 65 T is used to reveal the very different nature of carriers in monolayer and bulk transition metal dichalcogenides. In monolayer WSe2, the exciton emission shifts linearly with the magnetic field and exhibits a splitting that originates from the magnetic field induced valley splitting. The monolayer data can be described using a single particle picture with a Dirac-like Hamiltonian for massive Dirac Fermions, with an additional term to phenomenologically include the valley splitting. In contrast, in bulk WSe2 where the inversion symmetry is restored, transmission measurements show a distinctly excitonic behavior with absorption to the 1s and 2s states. Magnetic field induces a spin splitting together with a small diamagnetic shift and cyclotron like behavior at high fields, which is best described within the hydrogen model.

Acute administration of ucf-101 ameliorates the locomotor impairments induced by a traumatic spinal cord injury.

Secondary death of neural cells plays a key role in the physiopathology and the functional consequences of traumatic spinal cord injury (SCI). Pharmacological manipulation of cell death pathways leading to the preservation of neural cells is acknowledged as a main therapeutic goal in SCI. In the present work, we hypothesize that administration of the neuroprotective cell-permeable compound ucf-101 will reduce neural cell death during the secondary damage of SCI, increasing tissue preservation and reducing the functional deficits. To test this hypothesis, we treated mice with ucf-101 during the first week after a moderate contusive SCI. Our results reveal that ucf-101 administration protects neural cells from the deleterious secondary mechanisms triggered by the trauma, reducing the extension of tissue damage and improving motor function recovery. Our studies also suggest that the effects of ucf-101 may be mediated through the inhibition of HtrA2/OMI and the concomitant increase of inhibitor of apoptosis protein XIAP, as well as the induction of ERK1/2 activation and/or expression. In vitro assays confirm the effects of ucf-101 on both pathways as well as on the reduction of caspase cascade activation and apoptotic cell death in a neuroblastoma cell line. These results suggest that ucf-101 can be a promising therapeutic tool for SCI that deserves more detailed analyses.

High magnetic field reveals the nature of excitons in a single GaAs/AlAs core/shell nanowire.

Magneto-photoluminescence measurements of individual zinc-blende GaAs/AlAs core/shell nanowires are reported. At low temperature, a strong emission line at 1.507 eV is observed under low power (nW) excitation. Measurements performed in high magnetic field allowed us to detect in this emission several lines associated with excitons bound to defect pairs. Such lines were observed before in epitaxial GaAs of very high quality, as reported by Kunzel and Ploog. This demonstrates that the optical quality of our GaAs/AlAs core/shell nanowires is comparable to the best GaAs layers grown by molecular beam epitaxy. Moreover, strong free exciton emission is observed even at room temperature. The bright optical emission of our nanowires in room temperature should open the way for numerous optoelectronic device applications.

Comparison of the prevalence and distribution of human papillomavirus infection and cervical lesions between urban and native habitants of an Amazonian region of Peru.

We made a study of the prevalence of human papillomavirus (HPV) and cervix lesions in an Amazonian Bora native population (Bn) and compared it with the prevalence in an urban population in Iquitos (Iq). We also examined the distribution of HPV types among abnormal cervical smears in the Iq population. Swabs and cytologies were collected from 472 females. DNA consensus PCR, followed by direct sequencing, were used to determinate the HPV types in the swabs. Cytologies were classified based on the lesion grade. HPV prevalence was 43.9% in Iq and 35.4% in Bn. Cervix lesion prevalence was 20.0% in Iq and 0.3% in Bn. The frequency of high-risk HPV types among HPV+ females was 71.9% in Iq and 56.3% in Bn. The frequencies of low-risk and undetermined risk HPV types were 19.3/6.3% (Iq/ Bn) and 12.3/37.5% (Iq/Bn), respectively. In lesIq (women seeking cytological services with a previous cervix lesion diagnosis) the prevalence of HPV, was 72.9%. The incidence of carcinoma and high-grade squamous intraepithelial cervix lesions in lesIq were 31.2 and 18.8%, respectively. The Bn population had a lower incidence of high-risk HPV and cervix lesions. The high-risk strain HPV16 was significantly more frequent in Iq compared with Bn. lesIq high-risk HPVs were more frequent in high-grade squamous intraepithelial lesions and carcinoma. High-risk HPV16 prevalence was significantly higher than the prevalence of the other high-risk HPVs, especially in the high-grade squamous intraepithelial lesions and carcinoma.

[MALT lymphoma in a patient with Crohn's disease. A causal or incidental association?]. / Linfoma intestinal tipo MALT en una paciente con enfermedad de Crohn: asociación causal o casual?

We present the case of a 79-year-old woman who had received a diagnosis of Crohn's disease 3 years previously and who developed a mucosa-associated lymphoid tissue (MALT) lymphoma of the right colon while undergoing treatment with mesalazine. The patient had not received immunosuppressive drugs or infliximab. The possible association between Crohn's disease and the development of intestinal lymphomas is analyzed. The incidence, pathogenic mechanisms, diagnostic strategy, treatment and prognosis of these neoplasms are described, mainly with reference to MALT lymphomas of the colon.

Linfoma intestinal tipo MALT en una paciente con enfermedad de Crohn: ¿asociación causal o casual? / MALT lymphoma in a patient with Crohn’s disease. A causal or incidental association?

Se presenta el caso de una mujer de 79 años diagnosticada hacía 3 años de enfermedad de Crohn del colon, que desarrolló un linfoma tipo MALT de colon derecho estando en tratamiento con mesalazina y no habiendo recibido previamente fármacos inmunodepresores ni infliximab. Se analiza la posible asociación entre la enfermedad de Crohn y el desarrollo de linfomas intestinales: incidencia, mecanismos patogénicos, estrategia diagnóstica, tratamiento y pronóstico de esta neoplasia, haciendo alusión fundamentalmente al linfoma MALT de colon

We present the case of a 79-year-old woman who had received a diagnosis of Crohn's disease 3 years previously and who developed a mucosa-associated lymphoid tissue (MALT) lymphoma of the right colon while undergoing treatment with mesalazine. The patient had not received immunosuppressive drugs or infliximab. The possible association between Crohn's disease and the development of intestinal lymphomas is analyzed. The incidence, pathogenic mechanisms, diagnostic strategy, treatment and prognosis of these neoplasms are described, mainly with reference to MALT lymphomas of the colon