Dynamic range extension of SiPM detectors with the time-gated operation

The silicon photomultiplier (SiPM) is a novel detector technology that has undergone a fast development in the last few years, owing to its single-photon resolution and ultra-fast response time. However, the typical high dark count rates of the sensor may prevent the detection of low intensity radiation fluxes. In this article, the time-gated operation with short active periods in the nanosecond range is proposed as a solution to reduce the number of cells fired due to noise and thus increase the dynamic range. The technique is aimed at application fields that function under a trigger command, such as gated fluorescence lifetime imaging microscopy

Mejora de la implicación del alumnado en “Diseño y síntesis de sistemas digitales” usando e-learning colaborativo, gamificación y aprendizaje basado en problemas

[EN] During the last 3 years, it has been observed that the students do not have a solid base to understand the concepts that are introduced in the subject. In addition, the attitude of the students, in general, is negligence, do not review concepts to prepare the subject, do not prepare laboratory practices and stop attending class. This results in a high dropout rate, fear of doing the subject and discomfort with the teaching staff. To solve this problem, we apply the teaching innovation presented in this article. Such innovation takes advantage of teaching strategies such as gamification or problem-based learning, uses virtual tools to motivate elearning and collaboration with other students. The results, to date, are satisfactory since they reduce the dropout rate and increase the number of students who assimilate the concepts introduced in the subject[ES] Durante los últimos 3 años se ha observado que el alumnado no tiene una base sólida para entender los conceptos que se introducen en la asignatura. Además, la actitud de los alumnos, en general, es de dejadez, no repasan conceptos para preparar la asignatura, no se preparan las prácticas de laboratorio y dejan de asistir a las clases presenciales. Dando como resultado una alta tasa de abandono, miedo a realizar la asignatura y malestar con el profesorado. Para resolver esta problemática, se aplica la innovación docente presentada en este artículo. Dicha innovación saca beneficio de estratégias docentes como la gamificación o el aprendizaje basado en problemas, usa herramientas virtuales para motivar el “e-learning” y la colaboración con el resto de estudiantes. Los resultados, hasta la fecha, son satisfactorios dado que reducen la tasa de abandono e incrementan el número de estudiantes que asimilan los conceptos introducidos en la asignatura.Alonso, O.; Colomer, J.; Franch, N.; Diéguez, A. (2017). Mejora de la implicación del alumnado en “Diseño y síntesis de sistemas digitales” usando e-learning colaborativo, gamificación y aprendizaje basado en problemas. En In-Red 2017. III Congreso Nacional de innovación educativa y de docencia en red. Editorial Universitat Politècnica de València. 1303-1310. https://doi.org/10.4995/INRED2017.2017.6861OCS1303131

A Lamellar Zn-Based Coordination Polymer Showing Increasing Photoluminescence upon Dehydration

The present study reports on a 2D lamellar coordination polymer (CP) of {[Zn(µ3-pmdc)(H2O)]·H2O}n formula (pmdc = pyrimidine-4,6-dicarboxylate). This CP is synthesized under an appropriate acid-base reaction between the gently mortared reagents in the solid state through a solvent-free procedure that avoids the presence of concomitant byproducts. The X-ray crystal structure reveals the occurrence of Zn2 entities connected through carboxylate groups of pmdc, which behave as triconnected nodes, giving rise to six-membered ring-based layers that are piled up through hydrogen bonding interactions. In addition to a routine physico-chemical characterization, the thermal evolution of the compound has been studied by combining thermogravimetric and thermodiffractometric data. The photoluminescence properties are characterized in the solid state and the processes governing the spectra are described using time-dependent density-functional theory (TD-DFT) with two different approaches employing different program packages. The emissive capacity of the material is further analyzed according to the dehydration and decreasing temperature of the polycrystalline sampleThis research was funded by Gobierno Vasco/Eusko Jaurlaritza (IT1755-22, IT1722-22 and IT1500-22) and Junta de Andalucía (B-FQM-734-UGR20, ProyExcel_00386 and FQM-394)

Individually switchable InGaN/GaN nano-LED arrays as highly resolved illumination engines

GaN-based light emitting diodes (LEDs) have been shown to effectively operate down to nanoscale dimensions, which allows further downscaling the chip-based LED display technology from micro- to nanoscale. This brings up the question of what resolution limit of the illumination pattern can be obtained. We show two different approaches to achieve individually switchable nano-LED arrays. We evaluated both designs in terms of near-field spot size and optical crosstalk between neighboring pixels by using finite difference time domain (FDTD) simulations. The numerical results were compared with the performance data from a fabricated nano-LED array. The outcome underlines the influence of geometry of the LED array and materials used in contact lines on the final illumination spot size and shape

A Luminescent MOF Based on Pyrimidine-4,6-dicarboxylate Ligand and Lead(II) with Unprecedented Topology

In the present work, we report on a 3D MOF of {[Pb5(μ3-OH)(μ3-NO3)3(μ6-pmdc)3]·H2O}n formula (pmdc = pyrimidine-4,6-dicarboxylate) synthesized by an oven-heated, solvent-free procedure. The large connectivity afforded by the three ligands in their coordination to lead(II) ions grows cubic building units characterized by a central Pb atom with an unusual coordination index of 12 and 6 pmdc ligands occupying the faces. These cubic units are linked to one another giving rise to a quite condensed structure that represents an unprecedented topology showing the (4·62)6(43)2(45·610)3(45·68·82)6(46·69)6(612·83) point symbol. The crystalline material has been characterized by routine physico-chemical techniques to confirm its purity, and its thermal behaviour has been also studied by thermogravimetric and thermodiffractometric analyses. The solid presents a greenish blue photoluminescent emission based on pmdc ligands, as revealed by time-dependent density-functional theory (TDDFT) calculations, which is substantially more intense than in the free H2pmdc ligand according to its improved quantum yield. The emissive capacity of the material is further analysed according to decreasing temperature of the polycrystalline sample, finding that sizeable, long-lasting phosphorescence is present.This research was funded by Gobierno Vasco/Eusko Jaurlaritza (IT1755-22, IT1722-22 and IT1500-22) and Junta de Andalucía (ProyExcel_00386 and FQM-394). This publication is also part of the I+D+i projects of PGC2018-102052-A-C22 and PGC2018-102052-B-C21 codes, funded by MCIN/ AEI/10.13039/501100011033/ and “FEDER Una manera de hacer Europa”

Lanthanide(III) Ions and 5-Methylisophthalate Ligand Based Coordination Polymers: An Insight into Their Photoluminescence Emission and Chemosensing for Nitroaromatic Molecules

The work presented herein reports on the synthesis, structural and physico-chemical characterization, luminescence properties and luminescent sensing activity of a family of isostructural coordination polymers (CPs) with the general formula [Ln2(μ4-5Meip)3(DMF)]n (where Ln(III) = Sm (1Sm), Eu (2Eu), Gd (3Gd), Tb (4Tb) and Yb (5Yb) and 5Meip = 5-methylisophthalate, DMF = N,N-dimethylmethanamide). Crystal structures consist of 3D frameworks tailored by the linkage between infinite lanthanide(III)-carboxylate rods by means of the tetradentate 5Meip ligands. Photoluminescence measurements in solid state at variable temperatures reveal the best-in-class properties based on the capacity of the 5Meip ligand to provide efficient energy transfers to the lanthanide(III) ions, which brings intense emissions in both the visible and near-infrared (NIR) regions. On the one hand, compound 5Yb displays characteristic lanthanide-centered bands in the NIR with sizeable intensity even at room temperature. Among the compounds emitting in the visible region, 4Tb presents a high QY of 63%, which may be explained according to computational calculations. At last, taking advantage of the good performance as well as high chemical and optical stability of 4Tb in water and methanol, its sensing capacity to detect 2,4,6-trinitrophenol (TNP) among other nitroaromatic-like explosives has been explored, obtaining high detection capacity (with Ksv around 105 M−1), low limit of detection (in the 10−6–10−7 M) and selectivity among other molecules (especially in methanol).This work has been funded by University of the Basque Country (GIU20/028), Gobierno Vasco/Eusko Jaurlaritza (IT1755-22 and IT1500-22), Junta de Andalucía (FQM-394 and B-FQM-734-UGR20, B-FQM-478-UGR20 and ProyExcel_00386) and the Spanish Ministry of Economy and Competitiveness (MCIU/AEI/FEDER, UE) (PGC2018-102052-A-C22, PGC2018-102052-B-C21 and PID2020-117344RB-I00)

Irida-β-ketoimines derived from Hydrazines to Afford Metallapyrazoles or N-N Bond Cleavage: A Missing Metallacycle Disclosed by a Theoretical and Experimental Study

Unprecedented metallapyrazoles [IrH2{Ph2P(o-C6H4)CNNHC(o-C6H4)PPh2}] (3) and [IrHCl{Ph2P(o-C6H4)CNNHC(o-C6H4)PPh2}] (4) were obtained by the reaction of the irida-β-ketoimine [IrHCl{(PPh2(o-C6H4CO))(PPh2(o-C6H4CNNH2))H}] (2) in MeOH heated at reflux in the presence and absence of KOH, respectively. In solution, iridapyrazole 3 undergoes a dynamic process due to prototropic tautomerism with an experimental barrier for the exchange of ΔGcoal⧧ = 53.7 kJ mol–1. DFT calculations agreed with an intrapyrazole proton transfer process assisted by two water molecules (ΔG = 63.1 kJ mol–1). An X-ray diffraction study on 4 indicated electron delocalization in the iridapyrazole ring. The reaction of the irida-β-diketone [IrHCl{(PPh2(o-C6H4CO))2H}] (1) with H2NNRR′ in aprotic solvents gave irida-β-ketoimines [IrHCl{(PPh2(o-C6H4CO))(PPh2(o-C6H4CNNRR′))H}] (R = R′ = Me (5); R = H, R′ = Ph (8)), which can undergo N–N bond cleavage to afford the acyl–amide complex [IrHCl(PPh2(o-C6H4CO))(PPh2(o-C6H4C(O)N(CH3)2))-κP,κO] (6) or [IrHCl(PPh2(o-C6H4CO))(PPh2(o-C6H4CN)-κP)(NH2NHPh-κNH2)] (9) containing o-(diphenylphosphine)benzonitrile and phenylhydrazine, respectively. From a CH2Cl2/CH3OH solution of 9 kept at −18 °C, single crystals of [IrHCl(PPh2(o-C6H4CO))(PPh2(o-C6H4CN)-κP))(HN═NPh-κNH)] (10) containing o-(diphenylphosphine)benzonitrile and phenyldiazene were formed, as shown by X-ray diffraction. The reaction of 1 with methylhydrazine in methanol gave the hydrazine complex [IrCl(PPh2(o-C6H4CO))2(NH2NH(CH3)-κNH2)] (7). Single-crystal X-ray diffraction analysis was performed on 6 and 7.Partial financial support by Ministerio de Economía y Competitividad (CTQ2015-65268-C2-1-P and CTQ2015-65268-C2-2-P), Gobierno Vasco (S-PE13UN023), and Universidad del País Vasco (UPV/EHU) (GIU 13/06) is gratefully acknowledged. I.Z. is grateful to Gobierno Vasco for a scholarship. Technical and human support provided by IZO-SGI, SGIker (UPV/EHU, MICINN, GV/EJ, ERDF, and ESF) is gratefully acknowledged

Modificación del coeficiente peso/área del pié en relación con la agregación en Tarebia granifera

OBJECTIVE: To analyze specimens dispersion in a population of Tarebia granifera and its relationship with the change of morphometric parameters. METHODS: Two samplings by parcels including two types of substrata in opposite aggregation conditions were carried out, and the specimen abundance was compared between both samplings and substrata. The samples were stratified into classes according to shell height and for each of these the coefficient weight/foot-area was calculated and correlated with class size. It was experimentally evaluated whether specimens with a lower foot load had a better persistence in emerged substratum as well as the interaction between two class groups of shell height. RESULTS: The abundance difference between samplings was t=5.874 (pOBJETIVO: Analizar la dispersión de los ejemplares de una población de Tarebia granifera y su relación con la modificación de los parámetros morfométricos. METODOS: Se colectó por parcelas incluyendo dos tipos de substratos en condiciones opuestas de agregación y se comparó la abundancia relativa tanto entre muestreos, como entre sustratos. Se delimitaron 7 clases de alto a las cuales se les determinó el coeficiente peso/área del pié, el cual se correlacionó con la talla por clase. Se evaluó experimentalmente si los individuos con menor carga del pié tienen mayor persistencia en substratos emergidos, así como la interacción entre dos grupos de clases de alto. RESULTADOS: La diferencia de la abundancia entre los muestreos fue de t=5.874 (