Preferred growth direction by PbS nanoplatelets preserves perovskite infrared light harvesting for stable, reproducible, and efficient solar cells

Formamidinium-based perovskite solar cells (PSCs) present the maximum theoretical efficiency of the lead perovskite family. However, formamidinium perovskite exhibits significant degradation in air. The surface chemistry of PbS has been used to improve the formamidinium black phase stability. Here, the use of PbS nanoplatelets with (100) preferential crystal orientation is reported, to potentiate the repercussion on the crystal growth of perovskite grains and to improve the stability of the material and consequently of the solar cells. As a result, a vertical growth of perovskite grains, a stable current density of 23 mA cm(-2), and a stable incident photon to current efficiency in the infrared region of the spectrum for 4 months is obtained, one of the best stability achievements for planar PSCs. Moreover, a better reproducibility than the control device, by optimizing the PbS concentration in the perovskite matrix, is achieved. These outcomes validate the synergistic use of PbS nanoplatelets to improve formamidinium long-term stability and performance reproducibility, and pave the way for using metastable perovskite active phases preserving their light harvesting capability

Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above $\sim$1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form $\phi(E) = \phi_0 (E/E_{0})^{-\alpha -\beta\cdot{\rm{ln}}(E/E_{0})}$. The data is well-fit with values of $\alpha=2.63\pm0.03$, $\beta=0.15\pm0.03$, and log$_{10}(\phi_0~{\rm{cm}^2}~{\rm{s}}~{\rm{TeV}})=-12.60\pm0.02$ when $E_{0}$ is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be $\pm$50\% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of current-generation observatories and open a new view of 2/3 of the sky above 10 TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa

The 2HWC HAWC Observatory Gamma Ray Catalog

We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa

Lithium suppression of tau induces brain iron accumulation and neurodegeneration

Lithium is a first-line therapy for bipolar affective disorder. However, various adverse effects, including a Parkinson-like hand tremor, often limit its use. The understanding of the neurobiological basis of these side effects is still very limited. Nigral iron elevation is also a feature of Parkinsonian degeneration that may be related to soluble tau reduction. We found that magnetic resonance imaging T2 relaxation time changes in subjects commenced on lithium therapy were consistent with iron elevation. In mice, lithium treatment lowers brain tau levels and increases nigral and cortical iron elevation that is closely associated with neurodegeneration, cognitive loss and parkinsonian features. In neuronal cultures lithium attenuates iron efflux by lowering tau protein that traffics amyloid precursor protein to facilitate iron efflux. Thus, tau- and amyloid protein precursor-knockout mice were protected against lithium-induced iron elevation and neurotoxicity. These findings challenge the appropriateness of lithium as a potential treatment for disorders where brain iron is elevated (for example, Alzheimer’s disease), and may explain lithium-associated motor symptoms in susceptible patients

The Next White (NEW) detector

[EN] Conceived to host 5 kg of xenón at a pressure of 15 bar in the ¿ducial volume,the NEXTWhite (NEW)apparatus is currently the largest high pressure xenon gas TPC using electroluminescent ampli¿cation in the world. It is also a 1:2 scale model of the NEXT-100 detector scheduled to start searching for ßß0¿ decays in 136Xe in 2019. Both detectors measure the energy of the event using a plane of photomultipliers located behind a transparent cathode. They can also reconstruct the trajectories of charged tracks in the dense gas of the TPC with the help of a plane of silicon photomultipliers located behind the anode. A sophisticated gas system, common to both detectors, allows the high gas purity needed to guarantee a long electron lifetime. NEXT-White has been operating since October 2017 at the Canfranc Underground Laboratory (LSC), in Spain. This paper describes the detector and associated infrastructures.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union's Framework Programme for Research and Innovation Horizon 2020 (2014-2020) under the Marie Sklodowska-Curie Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economia y Competitividad of Spain under grants FIS2014-53371-C04, the Severo Ochoa Program SEV-2014-0398 and the Maria de Maetzu Program MDM-2016-0692; the GVA of Spain under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT and FEDER through the program COMPETE, projects PTDC/FIS-NUC/2525/2014 and UID/FIS/04559/2013; the U.S. Department of Energy under contract numbers DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A&M), DE-SC0017721 (University of Texas at Arlington), and DE-AC02-06CH11357 (Argonne National Laboratory); and the University of Texas at Arlington. We also warmly acknowledge the Laboratorio Nazionale di Gran Sasso (LNGS) and the Dark Side collaboration for their help with TPB coating of various parts of the NEXT-White TPC. Finally, we are grateful to the Laboratorio Subterraneo de Canfranc for hosting and supporting the NEXT experiment.Monrabal, F.; Gomez-Cadenas, JJ.; Toledo Alarcón, JF.; Laing, A.; Álvarez-Puerta, V.; Benlloch-Rodriguez, JM.; Carcel, S.... (2018). The Next White (NEW) detector. Journal of Instrumentation. 13:1-35. https://doi.org/10.1088/1748-0221/13/12/P12010S13513Nygren, D. (2009). High-pressure xenon gas electroluminescent TPC for 0-ν ββ-decay search. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 603(3), 337-348. doi:10.1016/j.nima.2009.01.222Gómez Cadenas, J. J., Álvarez, V., Borges, F. I. G., Cárcel, S., Castel, J., Cebrián, S., … Dias, T. H. V. T. (2014). Present Status and Future Perspectives of the NEXT Experiment. Advances in High Energy Physics, 2014, 1-22. doi:10.1155/2014/907067Martín-Albo, J., Muñoz Vidal, J., Ferrario, P., Nebot-Guinot, M., Gómez-Cadenas, J. J., … Cárcel, S. (2016). Sensitivity of NEXT-100 to neutrinoless double beta decay. Journal of High Energy Physics, 2016(5). doi:10.1007/jhep05(2016)159Álvarez, V., Borges, F. I. G., Cárcel, S., Castel, J., Cebrián, S., Cervera, A., … Díaz, J. (2013). Initial results of NEXT-DEMO, a large-scale prototype of the NEXT-100 experiment. Journal of Instrumentation, 8(04), P04002-P04002. doi:10.1088/1748-0221/8/04/p04002Álvarez, V., Borges, F. I. G., Cárcel, S., Castel, J., Cebrián, S., Cervera, A., … Díaz, J. (2013). Operation and first results of the NEXT-DEMO prototype using a silicon photomultiplier tracking array. Journal of Instrumentation, 8(09), P09011-P09011. doi:10.1088/1748-0221/8/09/p09011Álvarez, V., Borges, F. I. G. M., Cárcel, S., Castel, J., Cebrián, S., Cervera, A., … Díaz, J. (2013). Near-intrinsic energy resolution for 30–662keV gamma rays in a high pressure xenon electroluminescent TPC. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 708, 101-114. doi:10.1016/j.nima.2012.12.123Ferrario, P., Laing, A., López-March, N., Gómez-Cadenas, J. J., Álvarez, V., … Cebrián, S. (2016). First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment. Journal of High Energy Physics, 2016(1). doi:10.1007/jhep01(2016)104López-March, N. (2017). Sensitivity of the NEXT-100 detector to neutrinoless double beta decay. Journal of Physics: Conference Series, 888, 012243. doi:10.1088/1742-6596/888/1/012243Álvarez, V., Borges, F. I. G., Cárcel, S., Cebrián, S., Cervera, A., Conde, C. A. N., … Esteve, R. (2013). Ionization and scintillation response of high-pressure xenon gas to alpha particles. Journal of Instrumentation, 8(05), P05025-P05025. doi:10.1088/1748-0221/8/05/p05025Gehman, V. M., Seibert, S. R., Rielage, K., Hime, A., Sun, Y., Mei, D.-M., … Moore, D. (2011). Fluorescence efficiency and visible re-emission spectrum of tetraphenyl butadiene films at extreme ultraviolet wavelengths. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 654(1), 116-121. doi:10.1016/j.nima.2011.06.088Sanguino, P., Balau, F., Botelho do Rego, A. M., Pereira, A., & Chepel, V. (2016). Stability of tetraphenyl butadiene thin films in liquid xenon. Thin Solid Films, 600, 65-70. doi:10.1016/j.tsf.2016.01.006Silva, C., Pinto da Cunha, J., Pereira, A., Chepel, V., Lopes, M. I., Solovov, V., & Neves, F. (2010). Reflectance of polytetrafluoroethylene for xenon scintillation light. Journal of Applied Physics, 107(6), 064902. doi:10.1063/1.3318681Christophorou, L. G. (1988). Insulating gases. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 268(2-3), 424-433. doi:10.1016/0168-9002(88)90550-5Vijh, A. K. (1985). Relative electric strengths and polarizabilities of gaseous dielectrics. Materials Chemistry and Physics, 12(3), 287-296. doi:10.1016/0254-0584(85)90098-7Rebel, B., Hall, C., Bernard, E., Faham, C. H., Ito, T. M., Lundberg, B., … Wang, H. (2014). High voltage in noble liquids for high energy physics. Journal of Instrumentation, 9(08), T08004-T08004. doi:10.1088/1748-0221/9/08/t08004Cebrián, S., Pérez, J., Bandac, I., Labarga, L., Álvarez, V., Azevedo, C. D. R., … Cárcel, S. (2017). Radiopurity assessment of the energy readout for the NEXT double beta decay experiment. Journal of Instrumentation, 12(08), T08003-T08003. doi:10.1088/1748-0221/12/08/t08003Lung, K., Arisaka, K., Bargetzi, A., Beltrame, P., Cahill, A., Genma, T., … Yoshizawa, Y. (2012). Characterization of the Hamamatsu R11410-10 3-in. photomultiplier tube for liquid xenon dark matter direct detection experiments. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 696, 32-39. doi:10.1016/j.nima.2012.08.052Rodríguez, J., Toledo, J., Esteve, R., Lorca, D., & Monrabal, F. (2015). The front-end electronics for the 1.8-kchannel SiPM tracking plane in the NEW detector. Journal of Instrumentation, 10(01), C01025-C01025. doi:10.1088/1748-0221/10/01/c01025Carena, F., Carena, W., Chapeland, S., Chibante Barroso, V., Costa, F., Dénes, E., … von Haller, B. (2014). The ALICE data acquisition system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 741, 130-162. doi:10.1016/j.nima.2013.12.015Martoiu, S., Muller, H., Tarazona, A., & Toledo, J. (2013). Development of the scalable readout system for micro-pattern gas detectors and other applications. Journal of Instrumentation, 8(03), C03015-C03015. doi:10.1088/1748-0221/8/03/c03015Toledo, J., Muller, H., Esteve, R., Monzó, J. M., Tarazona, A., & Martoiu, S. (2011). The Front-End Concentrator card for the RD51 Scalable Readout System. Journal of Instrumentation, 6(11), C11028-C11028. doi:10.1088/1748-0221/6/11/c11028Esteve, R., Toledo, J., Rodríguez, J., Querol, M., & Álvarez, V. (2016). Readout and data acquisition in the NEXT-NEW Detector based on SRS-ATCA. Journal of Instrumentation, 11(01), C01008-C01008. doi:10.1088/1748-0221/11/01/c01008Esteve, R., Toledo, J., Monrabal, F., Lorca, D., Serra, L., Marí, A., … Mora, F. (2012). The trigger system in the NEXT-DEMO detector. Journal of Instrumentation, 7(12), C12001-C12001. doi:10.1088/1748-0221/7/12/c12001Herzenberg, A. (1969). Attachment of Slow Electrons to Oxygen Molecules. The Journal of Chemical Physics, 51(11), 4942-4950. doi:10.1063/1.1671887Huk, M., Igo-Kemenes, P., & Wagner, A. (1988). Electron attachment to oxygen, water, and methanol, in various drift chamber gas mixtures. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 267(1), 107-119. doi:10.1016/0168-9002(88)90635-3Novella, P., Palmeiro, B., Simón, A., Sorel, M., Adams, C., … Zuzel, G. (2018). Measurement of radon-induced backgrounds in the NEXT double beta decay experiment. Journal of High Energy Physics, 2018(10). doi:10.1007/jhep10(2018)112Saldanha, R., Grandi, L., Guardincerri, Y., & Wester, T. (2017). Model independent approach to the single photoelectron calibration of photomultiplier tubes. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 863, 35-46. doi:10.1016/j.nima.2017.02.086Simón, A., Felkai, R., Martínez-Lema, G., Monrabal, F., González-Díaz, D., Sorel, M., … Álvarez, V. (2018). Electron drift properties in high pressure gaseous xenon. Journal of Instrumentation, 13(07), P07013-P07013. doi:10.1088/1748-0221/13/07/p07013Martínez-Lema, G., Morata, J. A. H., Palmeiro, B., Botas, A., Ferrario, P., Monrabal, F., … Para, A. (2018). Calibration of the NEXT-White detector using 83mKr decays. Journal of Instrumentation, 13(10), P10014-P10014. doi:10.1088/1748-0221/13/10/p1001

Radiopurity control in the NEXT-100 double beta decay experiment: procedures and initial measurements

We have investigated the possibility of calibrating the PMTs of scintillation detectors, using the primary scintillation produced by X-rays to induce single photoelectron response of the PMT. The high-energy tail of this response, can be approximated to an exponential function, under some conditions. In these cases, it is possible to determine the average gain for each PMT biasing voltage from the inverse of the exponent of the exponential fit to the tail, which can be done even if the background and/or noise cover-up most of the distribution. We have compared our results with those obtained by the commonly used single electron response (SER) method, which uses a LED to induce a single photoelectron response of the PMT and determines the peak position of such response, relative to the pedestal peak (the electronic noise peak, which corresponds to 0 photoelectrons). The results of the exponential fit method agree with those obtained by the SER method when the average number of photoelectrons reaching the first dynode per light/scintillation pulse is around 1.0. The SER method has higher precision, while the exponential fit method has the advantage of being useful in situations where the PMT is already in situ, being difficult or even impossible to apply the SER method, e.g. in sealed scintillator/PMT devices

A phylogenetic classification of the world’s tropical forests

Knowledge about the biogeographic affinities of the world’s tropical forests helps to better understand regional differences in forest structure, diversity, composition and dynamics. Such understanding will enable anticipation of region specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present the first classification of the world’s tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (1) Indo-Pacific, (2) Subtropical, (3) African, (4) American, and (5) Dry forests. Our results do not support the traditional Neo- versus Palaeo-tropical forest division, but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar and India. Additionally, a northern hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern hemisphere forests

Sarilumab in patients admitted to hospital with severe or critical COVID-19: a randomised, double-blind, placebo-controlled, phase 3 trial

Background: Elevated proinflammatory cytokines are associated with greater COVID-19 severity. We aimed to assess safety and efficacy of sarilumab, an interleukin-6 receptor inhibitor, in patients with severe (requiring supplemental oxygen by nasal cannula or face mask) or critical (requiring greater supplemental oxygen, mechanical ventilation, or extracorporeal support) COVID-19. Methods: We did a 60-day, randomised, double-blind, placebo-controlled, multinational phase 3 trial at 45 hospitals in Argentina, Brazil, Canada, Chile, France, Germany, Israel, Italy, Japan, Russia, and Spain. We included adults (≥18 years) admitted to hospital with laboratory-confirmed SARS-CoV-2 infection and pneumonia, who required oxygen supplementation or intensive care. Patients were randomly assigned (2:2:1 with permuted blocks of five) to receive intravenous sarilumab 400 mg, sarilumab 200 mg, or placebo. Patients, care providers, outcome assessors, and investigators remained masked to assigned intervention throughout the course of the study. The primary endpoint was time to clinical improvement of two or more points (seven point scale ranging from 1 [death] to 7 [discharged from hospital]) in the modified intention-to-treat population. The key secondary endpoint was proportion of patients alive at day 29. Safety outcomes included adverse events and laboratory assessments. This study is registered with ClinicalTrials.gov, NCT04327388; EudraCT, 2020-001162-12; and WHO, U1111-1249-6021. Findings: Between March 28 and July 3, 2020, of 431 patients who were screened, 420 patients were randomly assigned and 416 received placebo (n=84 [20%]), sarilumab 200 mg (n=159 [38%]), or sarilumab 400 mg (n=173 [42%]). At day 29, no significant differences were seen in median time to an improvement of two or more points between placebo (12·0 days [95% CI 9·0 to 15·0]) and sarilumab 200 mg (10·0 days [9·0 to 12·0]; hazard ratio [HR] 1·03 [95% CI 0·75 to 1·40]; log-rank p=0·96) or sarilumab 400 mg (10·0 days [9·0 to 13·0]; HR 1·14 [95% CI 0·84 to 1·54]; log-rank p=0·34), or in proportions of patients alive (77 [92%] of 84 patients in the placebo group; 143 [90%] of 159 patients in the sarilumab 200 mg group; difference −1·7 [−9·3 to 5·8]; p=0·63 vs placebo; and 159 [92%] of 173 patients in the sarilumab 400 mg group; difference 0·2 [−6·9 to 7·4]; p=0·85 vs placebo). At day 29, there were numerical, non-significant survival differences between sarilumab 400 mg (88%) and placebo (79%; difference +8·9% [95% CI −7·7 to 25·5]; p=0·25) for patients who had critical disease. No unexpected safety signals were seen. The rates of treatment-emergent adverse events were 65% (55 of 84) in the placebo group, 65% (103 of 159) in the sarilumab 200 mg group, and 70% (121 of 173) in the sarilumab 400 mg group, and of those leading to death 11% (nine of 84) were in the placebo group, 11% (17 of 159) were in the sarilumab 200 mg group, and 10% (18 of 173) were in the sarilumab 400 mg group. Interpretation: This trial did not show efficacy of sarilumab in patients admitted to hospital with COVID-19 and receiving supplemental oxygen. Adequately powered trials of targeted immunomodulatory therapies assessing survival as a primary endpoint are suggested in patients with critical COVID-19. Funding: Sanofi and Regeneron Pharmaceuticals