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We present an innovative contactless method suitable to study in-plane thermal transport based on beam-offset frequency-domain thermoreflectance using a one-dimensional heat source with uniform power distribution. Using a one-dimensional heat source provides a number of advantages as compared to point-like heat sources, as typically used in time- and frequency-domain thermoreflectance experiments, just to name a few: (i) it leads to a slower spatial decay of the temperature field in the direction perpendicular to the line-shaped heat source, allowing to probe the temperature field at larger distances from the heater, hence, enhancing the sensitivity to in-plane thermal transport; (ii) the frequency range of interest is typically kHz. This rather low frequency range is convenient regarding the cost of the required excitation laser system but, most importantly, it allows the study of materials without the presence of a metallic transducer with almost no influence of the finite optical penetration depth of the pump and probe beams on the thermal phase lag, which arises from the large thermal penetration depth imposed by the used frequency range. We also show that for the case of a harmonic thermal excitation source, the phase lag between the thermal excitation and thermal response of the sample exhibits a linear dependence with their spatial offset, where the slope is proportional to the inverse of the thermal diffusivity of the material. We demonstrate the applicability of this method to the cases of: (i) suspended thin films of Si and PDPP4T, (ii) Bi bulk samples, and (iii) Si, glass, and highly-oriented pyrollitic graphite (HOPG) bulk samples with a thin metallic transducer. Finally, we also show that it is possible to study in-plane heat transport on substrates with rather low thermal diffusivity, e.g., glass, even using a metallic transducer. We achieve this by an original approach based on patterning the transducer using focused ion beam, with the key purpose of limiting in-plane heat transport through the thin metallic transducer., We acknowledge financial support from the Spanish Ministerio de Economía, Industria y Competitividad for its support through grant CEX2019-000917-S (FUNFUTURE) in the framework of the Spanish Severo Ochoa Centre of Excellence program, and grants PID2020-119777GB-I00 (THERM2MAIN), and PDC2021-121814-I00 (COVEQ). This work was financially supported by the European Commission through the Marie Sklodowska-Curie project HORATES (GA-955837). We also acknowledge grant 2021-SGR-00444 (NANOPTO) from AGAUR. K.X. acknowledges a fellowship (CSC201806950006) from China Scholarship Council and the Ph.D. programme in Materials Science from Universitat Autónoma de Barcelona in which he was enrolled. G.R and I.Z. acknowledge financial support from Eucor, The European Campus (Marie Sklodowska-Curie QUSTEC grant agreement no. 847471) and the Swiss National Science Foundation (Project Grant no. CRSII5 189924 )., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

The exceptional optoelectronic properties of metal halide perovskites (MHPs) are presumed to arise, at least in part, from the peculiar interplay between the inorganic metal-halide sublattice and the atomic or molecular cations enclosed in the cage voids. The latter can exhibit a roto-translative dynamics, which is shown here to be at the origin of the structural behavior of MHPs as a function of temperature, pressure and composition. The application of high hydrostatic pressure allows for unraveling the nature of the interaction between both sublattices, characterized by the simultaneous action of hydrogen bonding and steric hindrance. In particular, we find that under the conditions of unleashed cation dynamics, the key factor that determines the structural stability of MHPs is the repulsive steric interaction rather than hydrogen bonding. Taking as example the results from pressure and temperature-dependent photoluminescence and Raman experiments on MAPbBr$_3$ but also considering the pertinent MHP literature, we provide a general picture about the relationship between the crystal structure and the presence or absence of cationic dynamic disorder. The reason for the structural sequences observed in MHPs with increasing temperature, pressure, A-site cation size or decreasing halide ionic radius is found principally in the strengthening of the dynamic steric interaction with the increase of the dynamic disorder. In this way, we have deepened our fundamental understanding of MHPs; knowledge that could be coined to improve performance in future optoelectronic devices based on this promising class of semiconductors., 24 pages, 6 figures. Submitted to Sci. Rep. (under review)

El síndrome X frágil (SXF), constituye la primera causa de discapacidad intelectual hereditaria. Es una de las alteraciones más frecuentes aunque no siempre bien conocida por los profesionales de la salud, los educadores y la sociedad. El desconocimiento provoca que un porcentaje importante de afectados esté sin diagnosticar. Hay importantes diferencias entre comunidades autónomas, en algunas, el síndrome esta infradiagnosticado, no llevándose a cabo la detección, el consejo genético ni la adecuada intervención educativa. Tras revisar las características generales del SXF, presentamos el estudio realizado en la provincia de Burgos, recogiéndose datos de 273 varones con discapacidad intelectual, 57 fueron estudiados genéticamente resultando 13 nuevos afectados. Al menos, el 9,5% de varones atendidos en los centros de discapacidad intelectual en la provincia de Burgos, no diagnosticados por síndromes o discapacidades excluyentes, están afectados de SXF. La hoja de recogida de datos (HRD-1), seleccionó los participantes a estudiar genéticamente y con las modificaciones se ha obtenido la HRD-2, que consideramos sirve como protocolo facilitador para la preselección de posibles varones adultos afectados. Fragile X syndrome (FXS) is the first known cause of hereditary intellectual disability. Although one of the most common alterations, it is not always well known by health professionals, educators and society in general. This lack of knowledge means that a significant percentage of those affected are not diagnosed. Major differences among autonomous communities exist; in some of them, the syndrome is under diagnosed, due to non-detection, lack of genetic counselling or adequate educational intervention. After reviewing the general characteristics of FXS, we hereby present the study conducted in the province of Burgos, where data was gathered from 273 males with intellectual disability. 57 of them were genetically studied, resulting in the detection of 13 new cases of FXS. The data collection sheet (HRD-1) was the basis for selecting the participants to be studied; this, after undergoing the necessary modifications, resulted in HRD-2. We believe that this sheet can be used as a protocol to facilitate the pre-selection of possible affected adult males. At least 9.5% of males treated at the centres for the intellectually disabled in the province of Burgos, who have not been diagnosed with syndromes or exclusive disabilities, suffer from FXS.

El síndrome X frágil (SXF), constituye la primera causa de discapacidad intelectual hereditaria. Es una de las alteraciones más frecuentes aunque no siempre bien conocida por los profesionales de la salud, los educadores y la sociedad. El desconocimiento provoca que un porcentaje importante de afectados esté sin diagnosticar. Hay importantes diferencias entre comunidades autónomas, en algunas, el síndrome esta infradiagnosticado, no llevándose a cabo la detección, el consejo genético ni la adecuada intervención educativa. Tras revisar las características generales del SXF, presentamos el estudio realizado en la provincia de Burgos, recogiéndose datos de 273 varones con discapacidad intelectual, 57 fueron estudiados genéticamente resultando 13 nuevos afectados. Al menos, el 9,5% de varones atendidos en los centros de discapacidad intelectual en la provincia de Burgos, no diagnosticados por síndromes o discapacidades excluyentes, están afectados de SXF. La hoja de recogida de datos (HRD-1), seleccionó los participantes a estudiar genéticamente y con las modificaciones se ha obtenido la HRD-2, que consideramos sirve como protocolo facilitador para la preselección de posibles varones adultos afectados.