Magnetic cooling for microkelvin nanoelectronics on a cryofree platform

We present a parallel network of 16 demagnetization refrigerators mounted on a cryofree dilution refrigerator aimed to cool nanoelectronic devices to sub-millikelvin temperatures. To measure the refrigerator temperature, the thermal motion of electrons in a Ag wire -- thermalized by a spot-weld to one of the Cu nuclear refrigerators -- is inductively picked-up by a superconducting gradiometer and amplified by a SQUID mounted at 4 K. The noise thermometer as well as other thermometers are used to characterize the performance of the system, finding magnetic field independent heat-leaks of a few nW/mol, cold times of several days below 1 mK, and a lowest temperature of 150 microK of one of the nuclear stages in a final field of 80 mT, close to the intrinsic SQUID noise of about 100 microK. A simple thermal model of the system capturing the nuclear refrigerator, heat leaks, as well as thermal and Korringa links describes the main features very well, including rather high refrigerator efficiencies typically above 80%.Comment: 4 color figures, including supplementary inf

Porous silicon solar cells

We developed a new process for the fabrication of crystalline solar cell, based on an ultrathin silicon membrane, taking advantage of porous silicon technology. The suggested architecture allows the costs reduction of silicon based solar cell reusing the same wafer to produce a great number of membranes. The architectures combines the efficiency of crystalline silicon solar cell, with the great absorption of porous silicon, and with a more efficient way to use the material. The new process faces the main challenge to achieve an effective and not expensive passivation of the porous silicon surface, in order to achieve an efficient photovoltaic device. At the same time the process suggests a smart way to selective doping of the macroporous silicon layers despite the through-going pores. © 2015 IEEE. SciVal Topic Prominence  Topic: Porous silicon | Silicon | macroporous silicon Prominence percentile: 66.984  Author keywords nanofabricationporous siliconsilicon nanoelectronicssolar cells Indexed keywords Engineering controlled terms: Crystalline materialsNanoelectronicsNanostructured materialsNanotechnologyPorous siliconSiliconSilicon wafersSolar cells Engineering uncontrolled terms Crystalline silicon solar cellsCrystalline solar cellsMacro porous siliconPhotovoltaic devicesPorous silicon surfacesPorous silicon technologySilicon nanoelectronicsUltrathin silicon membrane Engineering main heading: Silicon solar cells ISBN: 978-146738155-0 Source Type: Conference Proceeding Original language: English DOI: 10.1109/NANO.2015.7388710 Document Type: Conference Paper Sponsors: Nanotechnology Council Publisher: Institute of Electrical and Electronics Engineers Inc. References (9) View in search results format ▻ All Export  Print  E-mail Save to PDF Create bibliography 1 (2012) International Technology Roadmap for Photovoltaics Results 2012. Cited 24 times. ITRPV, Third Edition, Berlin 2012 www.ITRPV.net 2 Lehmann, V., Honlein, W., Stengl, R., Willer, J., Wendt, H. (1992) Verfahren Zur Herstellung Einer Solarzelle Aus Einer Substratscheibe. Cited 6 times. German patent DE4204455C1; Filing date: 29. 01. 3 Brendel, R., Ernst, M. Macroporous Si as an absorber for thin-film solar cells (2010) Physica Status Solidi - Rapid Research Letters, 4 (1-2), pp. 40-42. Cited 22 times. http://www3.interscience.wiley.com/cgi-bin/fulltext/123215552/PDFSTART doi: 10.1002/pssr.200903372 Locate full-text(opens in a new window) View at Publisher 4 Ernst, M., Brendel, R., Ferré, R., Harder, N.-P. Thin macroporous silicon heterojunction solar cells (2012) Physica Status Solidi - Rapid Research Letters, 6 (5), pp. 187-189. Cited 16 times. doi: 10.1002/pssr.201206113 Locate full-text(opens in a new window) View at Publisher 5 Ernst, M., Brendel, R. Macroporous silicon solar cells with an epitaxial emitter (2013) IEEE Journal of Photovoltaics, 3 (2), art. no. 6472253, pp. 723-729. Cited 7 times. doi: 10.1109/JPHOTOV.2013.2247094 Locate full-text(opens in a new window) View at Publisher 6 Ernst, M., Schulte-Huxel, H., Niepelt, R., Kajari-Schröder, S., Brendel, R. Thin crystalline macroporous silicon solar cells with ion implanted emitter (Open Access) (2013) Energy Procedia, 38, pp. 910-918. Cited 2 times. http://www.sciencedirect.com/science/journal/18766102 doi: 10.1016/j.egypro.2013.07.364 Locate full-text(opens in a new window) View at Publisher 7 Nenzi, P., Kholostov, K., Crescenzi, R., Bondarenka, H., Bondarenko, V., Balucani, M. Electrochemically etched TSV for porous silicon interposer technologies (2013) Proceedings - Electronic Components and Technology Conference, art. no. 6575887, pp. 2201-2207. Cited 2 times. ISBN: 978-147990233-0 doi: 10.1109/ECTC.2013.6575887 Locate full-text(opens in a new window) View at Publisher 8 Perticaroli, S., Varlamava, V., Palma, F. Microwave sensing of nanostructured semiconductor surfaces (2014) Applied Physics Letters, 104 (1), art. no. 013110. Cited 3 times. doi: 10.1063/1.4861424 Locate full-text(opens in a new window) View at Publisher 9 De Cesare, G., Caputo, D., Tucci, M. Electrical properties of ITO/crystalline-silicon contact at different deposition temperatures (2012) IEEE Electron Device Letters, 33 (3), art. no. 6142006, pp. 327-329. Cited 28 times. doi: 10.1109/LED.2011.2180356 Locate full-text(opens in a new window) View at Publisher © Copyright 2017 Elsevier B.V., All rights reserved. ◅ Back to results ◅ Previous 3of10 Next ▻  Top of page Metrics Learn more about article metrics in Scopus (opens in a new window)  0 Citations in Scopus 0 Learn more about Field-Weighted Citation Impact Field-Weighted Citation Impact PlumX Metrics Usage, Captures, Mentions, Social Media and Citations beyond Scopus.  Cited by 0 documents Inform me when this document is cited in Scopus: Set citation alert ▻ Set citation feed ▻ Related documents Thin crystalline macroporous silicon solar cells with ion implanted emitter Ernst, M. , Schulte-Huxel, H. , Niepelt, R. (2013) Energy Procedia Multilayer etching for kerf-free solar cells from macroporous silicon Schäfer, S. , Ernst, M. , Kajari-Schröder, S. (2013) Energy Procedia Macroporous silicon solar cells with an epitaxial emitter Ernst, M. , Brendel, R. (2013) IEEE Journal of Photovoltaics View all related documents based on references Find more related documents in Scopus based on: Authors ▻ Keywords ▻ About Scopus What is Scopus Content coverage Scopus blog Scopus API Privacy matters Language 日本語に切り替える 切换到简体中文 切換到繁體中文 Русский язык Customer Service Help Contact us Elsevier Terms and conditions ↗ Privacy policy ↗ Copyright © 2018 Elsevier B.V ↗. All rights reserved. Scopus® is a registered trademark of Elsevier B.V. We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies. RELX Group We developed a new process for the fabrication of crystalline solar cell, based on an ultrathin silicon membrane, taking advantage of porous silicon technology. The suggested architecture allows the costs reduction of silicon based solar cell reusing the same wafer to produce a great number of membranes. The architectures combines the efficiency of crystalline silicon solar cell, with the great absorption of porous silicon, and with a more efficient way to use the material. The new process faces the main challenge to achieve an effective and not expensive passivation of the porous silicon surface, in order to achieve an efficient photovoltaic device. At the same time the process suggests a smart way to selective doping of the macroporous silicon layers despite the through-going pores

Distribución de copépodos epipelágicos en el Pacífico ecuatorial oriental durante el evento débil de La Niña de 2001

We determined the distribution and abundance of pelagic copepods in the eastern equatorial Pacific between the coast of Ecuador and the Galapagos Islands under oceanographic conditions associated with the weak La Niña event of 2001. In September-October 2001, negative anomalies of sea surface temperature from this event still remained in the eastern equatorial Pacific, mainly between Ecuador and the Galapagos Islands. The event allowed the incursion of the Humboldt Current farther north and of the Equatorial Undercurrent into the study area, favouring a strong Equatorial Front and upwelling processes. There was evidence of mesoscale eddies in the study area and of the presence of the South Equatorial Current going westward at about 1°N. We identified 107 copepod species and analyzed the distribution of the 10 most abundant ones: Oncaea venusta, Subeucalanus pileatus, S. crassus, S. subtenuis, Paraeucalanus attenuatus, Pleuromamma borealis, Scolecithrix danae, Clausocalanus farrani, Temora discaudata and Calanus chilensis. Copepod distribution and abundance exhibited marked latitudinal differences related to the oceanographic conditions; abundance was highest to the southeast of the Galapagos Islands. Oncaea venusta, Pleuromamma borealis, Calanus chilensis, and Subeucalanus subtenuis were the species that best defined the Equatorial Front and the upwelling process.Se determinó la distribución y abundancia de los copépodos epipelágicos en el Pacífico Ecuatorial Oriental, entre la costa de Ecuador e islas Galápagos, durante condiciones oceanográficas asociadas al evento débil de La Niña 2001. Al final de este evento (Septiembre-Octubre 2001), aun se registraban las anomalías de temperatura superficial en el Pacífico Ecuatorial Oriental, en el área de estudio. Este evento favoreció la incursión hacia el norte de la Corriente de Humboldt y la Subcorriente Ecuatorial, como también la intensificación del Frente Ecuatorial. Se evidenció la presencia de remolinos de mesoescala y de la Corriente Surecuatorial hacia el oeste, alrededor de 1ºN. Se identificaron 107 especies de copépodos y se analizó la distribución de las diez especies más abundantes (Oncaea venusta, Subeucalanus pileatus, S. crassus, S. subtenuis, Paraeucalanus. attenuatus, Pleuromamma borealis, Scolecithrix danae, Clausocalanus farrani, Temora discaudata y Calanus chilensis). La distribución y abundancia de estas especies presentó marcadas diferencias latitudinales asociadas a las condiciones oceanográficas, que mostraron las mayores densidades al sureste de las islas Galápagos. Oncaea venusta, Pleuromamma borealis, Calanus chilensis y Subeucalanus subtenuis fueron las especies que mejor definieron el Frente Ecuatorial y los eventos de surgencia

Magnetic cooling and on-chip thermometry for nanoelectronics below 10 mK

Cooling of electronic devices below 1 mK is a challenging task, since the thermal coupling with the dilution refrigerator becomes weak at low temperatures and electronic devices are extremely susceptible to external heat leaks such as microwave radiation and electrical noise. Despite these technological challenges, there is a completely new world of physics which can be explored once low temperatures are achieved. To reach such ultra-low temperatures, we implemented a parallel network of Nuclear Refrigerators, to adapt magnetic cooling to electronic transport measurements. The cooling scheme relies on the cooling of each individual lead by its own nuclear refrigerator to transfer cooling power down to the sample. Here, we present the implementation of a parallel network of nuclear refrigerators for the first time on a cryo-free system. One challenge is the increased vibrations level compared to the wet cryostat, but a careful damping of the vibrations is possible, thus enabling low temperature experiments. The setup successfully cools the electronic temperature of the nuclear refrigerant down to 150 microK and limits a residual heat leak of few nW per mole of copper, allowing to stay below 1 mK for several days. A simple thermal model capturing the demagnetization process, the heat leak, the coupling between electron and nuclei as well as the efficiency of the process typically above 80%. To characterize the cooling capacity of our system, we cool several electronic devices well below 10 mK. We cool a normal metal-insulator-superconducting tunnel junction down to 7.3 mK. Further lowering temperatures might be limited by the heat release of the socket. However, a theoretical estimate shows that such a device has the potential to reach 1 mK, since the overheating effects turn out to be negligible. Indeed, by using the thermal broadening of sub-gap current steps, we demonstrate the cooling of the tunnel junction down to 4 mK. These steps are novel features which are weakly-coupled and more robust than the conventional NIS thermometry, and we can model them as Andreev bound states enhanced by disorder and the geometry of the junction. Additionally, other physical properties of the junction are investigated experimentally and numerically, such as two-particle sub-gap tunneling current promoted by the disorder and the geometry of the junction and magnetic field suppression of a minigap. Further improvement on the cooling of the electronic device is achieved by on-chip magnetic refrigeration. We demonstrate magnetic cooling of an array of Coulomb Blockade Thermometers with huge copper islands. The lowest temperature reached is 2.8 mK, which is the lowest temperature measured to date in a solid state electronic device. The reduction in temperature is roughly a factor 8 during the demagnetization process, showing an improved efficiency of the cooling technique compared to the previous experiments. The temperature might possibly be further reduced below 1 mK, by introducing non-inductive filters and damping more the vibrations, which would lead to a lower precooling temperature and an improved efficiency of the on-chip magnetic cooling

Serum Selenium and Incident Cardiovascular Disease in the PREvención con DIeta MEDiterránea (PREDIMED) Trial: Nested Case-Control Study

Background: Selenium is an essential trace mineral with potential interest for cardiovascular disease (CVD) prevention owing to its antioxidant properties. Epidemiological data on selenium status and CVD remain inconsistent. The objective of this study was to ascertain whether low serum selenium (SSe) concentrations are related to an increased risk of a first CVD event in a population at high cardiovascular risk. Methods: We undertook a case-control study nested within the “PREvención con DIeta MEDiterránea” (PREDIMED) trial. A total of 207 participants diagnosed with CVD (myocardial infarction, stroke, or cardiovascular death) during the follow-up period (2003–2010) were matched by sex, age, and intervention group to 436 controls by incidence density sampling. Median time between serum sample collection and subsequent CVD event occurrence was 0.94 years. SSe levels were determined using inductively coupled plasma mass spectrometry analysis. Covariates were assessed through validated questionnaires, in-person interviews, and medical record reviews. Conditional logistic regression was used to calculate multivariable-adjusted odds ratios (ORs). Results: Among women, the mean SSe concentration was lower in cases than in controls (98.5 g/L vs. 103.8 g/L; p = 0.016). In controls, SSe levels were directly associated with percentage of total energy intake from proteins and fish intake (p for linear trend < 0.001 and 0.049, respectively), whereas SSe concentrations were inversely associated with age, body mass index, and percentage of total energy intake from carbohydrates (p for linear trend < 0.001, 0.008 and 0.016 respectively). In the total group, we observed an inverse dose–response gradient between SSe levels and risk of CVD in the fully-adjusted model (highest vs. lowest quartile: OR = 0.47, 95% CI: 0.27–0.81; ptrend = 0.003). Conclusions: Among elderly individuals at high cardiovascular risk, high SSe concentrations within population reference values are associated with lower first CVD incidence.official funding agency for biomedical research of the Spanish government, Instituto de Salud Carlos III (ISCIII) RTIC G03/140RTIC RD 06/0045 "PREDIMED" JR14/00008Spanish government, Instituto de Salud Carlos III (ISCIII), through Centro de Investigacion Biomedica en Red de Fisiopatologia de la Obesidad y Nutricion (CIBERobn)Centro Nacional de Investigaciones Cardiovasculares CNIC 06/2007Fondo de Investigacion Sanitaria-Fondo Europeo de Desarrollo Regional (Proyecto de Investigacion) PI04-2239 PI05/2584 CP06/00100 PI07/0240 PI07/1138 PI07/0954 PI 07/0473 PI10/01407 PI10/02658 PI11/01647 P11/02505 PI13/00462Ministry of Science and Innovation, Spain (MICINN) (AGL)-2009-13906-C02 AGL2010-22319-C03 AGL2013-49083C3-1-RMinisterio de Economia y Competitividad-Fondos FEDER-Instituto de Salud Carlos III UNGR15-CE-3380 Fundacion Mapfre 2010Junta de Andalucia PI0105/2007Public Health Division of the Department of Health of the Autonomous Government of CataloniaCenter for Forestry Research & Experimentation (CIEF) GVACOMP 06109 GVACOMP2010-181 GVACOMP2011-151 PROMETEO 21/2021Conselleria de Sanitat y Atencion Primaria CS2010-AP-111 CS2011-AP-042Regional Government of Navarra P27/2011Centre Catala de la Nutricio de l'Institut d'Estudis Catalan

NUMEROS CROMOSOMICOS DE PTERIDOFITOS CHILENOS: PRIMERA CONTRIBUCION

Mitotic chromosome counts in Chilean pteridophytes confirm the diploidy described for Equisetum L. (2n = 216) andBlechnum L. (2n = 66), as well as the tetraploidy of Asplenium L. (2n = 144). Megalastrum spectabile (Kaulf.) A.R.Sm.et R.C.Moran is diploid (2n = 82), while in metaphases of Polystichum subintegerrimum (Hook. et Arn.) R.A.Rodr.chromosome numbers from ca. 311 to 328 were counted. Tetraploidy was also described in Adiantum chilense Kaulf.(2n = 116)

De las zonas con necesidades de transformación social en andalucía, a la intervención en zonas desfavorecidas

El pasado mes de agosto el gobierno de la Junta de Andalucía aprobaba la “Estrategia Regional Andaluza para la Cohesión e Inclusión Social. Intervención en zonas desfavorecidas (ERACIS)”. La estrategia viene a marcar las líneas de actuación y objetivos para intervenir en los barrios vulnerables andaluces, que han sido catalogados en un total de 99. Esta estrategia es un punto y seguido de un proceso comenzado en 1989 cuando se aprueba el Plan de Barriadas de Actuación Preferente de la Junta de Andalucía, en aquel momento con 8 barriadas identificadas como tal. En este tiempo transcurrido con la utilización de importantes recursos económicos, y el esfuerzo de cientos de profesionales en un porcentaje muy importante trabajadores sociales, los indicadores de exclusión social que definen estas barriadas no han hecho, sino que incrementarse en las distintas provincias andaluzas. Donde el modelo de desarrollo urbanístico fue y siguen siendo, uno de los principales elementos que han venido planteando diferentes estudios a la hora de diagnosticar el porque del surgimiento de estos barrios. En cuanto a la intervención desarrollada, el ámbito comunitario no se encontraba entre los objetivos a alcanzar, hecho que se ha modificado en los nuevos objetivos que establece la estrategia regional ya aludida. Por lo que, a través del análisis normativo, como de los indicadores y los propios objetivos, se abre un espacio para la reflexión sobre las prioridades de ejecución en estos barrios y los modelos de intervención, sin olvidar que, aunque haya elementos comunes en ellos cada uno tiene su propia idiosincrasia por lo que las acciones deben ser específicas, cercanas y en consonancia con la realidad del territorio, a la vez que definir cuáles deben de ser los ejes de actuación desde lo comunitario.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech