High-Tc bolometers with silicon-nitride spiderwebsuspension for far-infrared detection

High-Tc GdBa2Cu3O7-δ (GBCO) superconducting transition edge bolometers with operating temperatures near 90 K have been made with both closed silicon-nitride membranes and patterned silicon-nitride (SiN) spiderweb-like suspension structures. As a substrate silicon-on-nitride (SON) wafers are used which are made by fusion bonding of a silicon wafer to a silicon wafer with a silicon-nitride top layer. The resulting monocrystalline silicon top layer on the silicon-nitride membranes enables the epitaxial growth of GBCO. By patterning the silicon-nitride the thermal conductance G is reduced from about 20 to 3 μW/K. The noise of both types of bolometers is dominated by the intrinsic noise from phonon fluctuations in the thermal conductance G. The optical efficiency in the far infrared is about 75% due to a goldblack absorption layer. The noise equivalent power NEP for FIR detection is 1.8 pW/√Hz, and the detectivity D* is 5.4×1010 cm √Hz/W. Time constants are 0.1 and 0.6 s, for the closed membrane and the spiderweb like bolometers respectively. The effective time constant can be reduced with about a factor 3 by using voltage bias. Further reduction necessarily results in an increase of the NEP due to the 1/f noise of the superconductor

A new type of carbon resistance thermometer with excellent thermal contact at millikelvin temperatures

Using a new brand of commercially available carbon resistor we built a cryogenic thermometer with an extremely good thermal contact to its thermal environment. Because of its superior thermal contact the thermometer is insensitive to low levels of spurious radio frequency heating. We calibrated our thermometer down to 5mK using a quartz tuning fork He-3 viscometer and measured its thermal resistance and thermal response time.Comment: 5 pages, 4 figure

Pharmacological Interventions to Ameliorate Neuropathological Symptoms in a Mouse Model of Lafora Disease

14 páginas; 9 figuras.Lafora disease (LD, OMIM 254780) is a rare fatal neurodegenerative disorder that usually occurs during childhood with generalized tonic-clonic seizures, myoclonus, absences, drop attacks or visual seizures. Unfortunately, at present, available treatments are only palliatives and no curative drugs are available yet. The hallmark of the disease is the accumulation of insoluble polyglucosan inclusions, called Lafora bodies (LBs), within the neurons but also in heart, muscle and liver cells. Mouse models lacking functional EPM2A or EPM2B genes (the two major loci related to the disease) recapitulate the Lafora disease phenotype: they accumulate polyglucosan inclusions, show signs of neurodegeneration and have a dysregulation of protein clearance and endoplasmic reticulum stress response. In this study, we have subjected a mouse model of LD (Epm2b-/-) to different pharmacological interventions aimed to alleviate protein clearance and endoplasmic reticulum stress. We have used two chemical chaperones, trehalose and 4-phenylbutyric acid. In addition, we have used metformin, an activator of AMP-activated protein kinase (AMPK), as it has a recognized neuroprotective role in other neurodegenerative diseases. Here, we show that treatment with 4-phenylbutyric acid or metformin decreases the accumulation of Lafora bodies and polyubiquitin protein aggregates in the brain of treated animals. 4-Phenylbutyric acid and metformin also diminish neurodegeneration (measured in terms of neuronal loss and reactive gliosis) and ameliorate neuropsychological tests of Epm2b-/- mice. As these compounds have good safety records and are already approved for clinical uses on different neurological pathologies, we think that the translation of our results to the clinical practice could be straightforward.This work was supported by grants from the Spanish Ministry of Education and Science SAF2011-27442, Fundació La Marato de TV3 (ref. 100130) and an ACCI2012 action from CIBERER. A.B. holds a postdoctoral fellowship from the Program “Junta para la Ampliación de Estudios” (JAE-Doc) co-funded by the European Social Fund (ESF).Peer reviewe

Efectividad del aceite esencial de orégano mexicano de República Dominicana (Lippia graveolens) contra plagas del maíz (Sitophilus zeamais y Fusarium verticillioides)

The insecticidal and antifungal properties of Mexican oregano (Lippia graveolens) essential oil from the Dominican Republic were investigated under laboratory conditions against two main pests of stored grains: Sitophilus zeamais and Fusarium verticillioides. Although oregano essential oil at 600 ?l/l air did not result in a significant mortality of S. zeamais after 24 hours of exposure by fumigation, this essential oil was a powerful acetylcholinesterase (AChE) inhibitor in vitro. One of the main components of oregano essential oil, p-cymene, presented fumigant toxicity and AChE inhibition activity against the maize weevil. The L. graveolens essential oil antifungal activity against F. verticillioides was evaluated at 50, 100 and 200 ?l/l, and it was found that growth parameters were affected by the presence of oregano essential oil in the media, whereas FB1 production was not inhibited. The results demonstrate that oregano essential oil and p-cymene can be used as alternatives to synthetic pesticides against F. verticillioides and S. zeamais, respectively.Se estudiaron en condiciones de laboratorio las propiedades insecticidas y fungicidas del aceite esencial de orégano mexicano (Lippia graveolens) de República Dominicana contra dos plagas principales de granos almacenados: Sitophilus zeamais y Fusarium verticillioides. Aunque el aceite esencial de orégano a 600 ?l/l de aire no resultó en una mortalidad significativa de S. zeamais después de 24 horas de exposición a la fumigación, fue un potente inhibidor de la acetilcolinesterasa (AChE) in vitro. El p-cimeno, uno de los principales componentes del aceite esencial, presentó actividad fumigante y de inhibición de la AChE contra el gorgojo del maíz. Además se evaluó la actividad antifúngica frente a F. verticillioides a 50, 100 y 200 ?l/l y se encontró que los parámetros de crecimiento del hongo fueron afectados por la presencia del aceite esencial de orégano en el medio, mientras que la producción de fumonisina B1 (FB1) no se inhibió. Los resultados demuestran que el aceite esencial de orégano y el p-cimeno se pueden usar como alternativas a los pesticidas sintéticos contra F. verticillioides y S. zeamais, respectivamente

Interdigitated μ-electrodes for development of an impedimetric immunosensor for atrazine detection.

This contribution describes the development of an impedimetric immunosensor for atrazine detection. This immunosensor is based on the use of interdigitated metallic μ-electrodes (IDμEs) The method described in this work does not use any redox mediator and relies on the direct detection of immunochemical competitive reaction between the pesticide and a haptenized-protein immobilized on interdigitated μ-electrodes for the specific antibody. The immunoreagents used were specifically developed to detect atrazine. The immunochemical detection of this pesticide is achieved without using any label. The immunosensor shows a limit of detection of 8.34±1.37 μg L-1, witch is lower than the Maximun Residue Level (MRL) (50μg L-1)established by EU (European Union)for residues of atrazine as herbicide in the wine grapes and other foodstuff products.Peer ReviewedPostprint (published version

Low noise far-infrared detection at 90 K using high-T(c) superconducting bolometers with silicon-nitride beam suspension

High-T(c) GdBa2Cu3O7-d (GBCO) superconducting transition edge bolometers with operating temperatures near 90 K and receiving area of 1 mm2 have been made with both closed silicon-nitride membranes and patterned silicon-nitride (Si(x)N(y)) spiderweb-like suspension structures. To enable epitaxial growth of the GBCO layer, a thin monocrystalline Si layer is prepared on the silicon-nitride base, using fusion bonding techniques. By pattering the silicon-nitride supporting membrane the thermal conductance G is reduced from 20 to 3.5 μW/K. The noise of both types of bolometers is fully dominated by the intrinsic noise from phonon fluctuations in the thermal conductance G. The optical efficiency in the far infrared is about 75% due to a gold black absorption layer. The optical noise equivalent power (NEP) is 1.8 pW/√Hz, and the detectivity D* is 5.4x1010 cm√Hz/W. Time constants are 0.1 and 0.6 s, for the closed membrane and the spiderweb like bolometers respectively. We have observed an empirical limit for the NEP for this type of bolometers. The effective timeconstant can be reduced with a factor of 3 by using an electronic feedback system or by using voltage bias. A further reduction necessarily results in an increase of the NEP due to the 1/f noise of the superconductor

Association between preoperative levels of 25-hydroxyvitamin D and hospital-acquired infections after hepatobiliary surgery: A prospective study in a third-level hospital

Introduction Evidence implicates vitamin D deficiency in poorer outcomes and increased susceptibility to hospital-acquired infections (HAIs). This study examined the association between serum vitamin D levels and HAIs in a population of hepatobiliary surgery patients. Methods Participants in this prospective analytical observational study were patients who underwent hepatobiliary surgery in a tertiary hospital in Aragon, Spain, between February 2018 and March 2019. Vitamin D concentrations were measured at admission and all nosocomial infections during hospitalization and after discharge were recorded. Results The mean 25-hydroxyvitamin D concentration of the study population (n = 301) was 38.56 nmol/L, which corresponds to vitamin D deficiency. Higher vitamin D concentrations were associated with a decreased likelihood of developing a HAI in general (p = 0.014), and in particularly surgical site infection (p = 0.026). The risk of HAI decreased by 34% with each 26.2-nmol/L increase in serum vitamin D levels. Conclusions Vitamin D levels may constitute a modifiable risk factor for postoperative nosocomial infections in hepatobiliary surgery patients

Magnetization of a two-dimensional electron gas with a second filled subband

We have measured the magnetization of a dual-subband two-dimensional electron gas, confined in a GaAs/AlGaAs heterojunction. In contrast to two-dimensional electron gases with a single subband, we observe non-1/B-periodic, triangularly shaped oscillations of the magnetization with an amplitude significantly less than $1 \mu_{\mathrm{B}}^*$ per electron. All three effects are explained by a field dependent self-consistent model, demonstrating the shape of the magnetization is dominated by oscillations in the confining potential. Additionally, at 1 K, we observe small oscillations at magnetic fields where Landau-levels of the two different subbands cross.Comment: 4 pages, 4 figure

Tumor slice culture system to assess drug response of primary breast cancer

Background The high incidence of breast cancer has sparked the development of novel targeted and personalized therapies. Personalization of cancer treatment requires reliable prediction of chemotherapy responses in individual patients. Effective selection can prevent unnecessary treatment that would mainly result in the unwanted side effects of the therapy. This selection can be facilitated by characterization of individual tumors using robust and specific functional assays, which requires development of powerful ex vivo culture systems and procedures to analyze the response to treatment. Methods We optimized culture methods for primary breast tumor samples that allowed propagation of tissue ex vivo. We combined several tissue culture strategies, including defined tissue slicing technology, growth medium optimization and use of a rotating platform to increase nutrient exchange. Results We could maintain tissue cultures for at least 7 days without losing tissue morphology, viability or cell proliferation. We also developed methods to determine the cytotoxic response of individual tumors to the chemotherapeutic treatment FAC (5-FU, Adriamycin [Doxorubicin] and Cyclophosphamide). Using this tool we designated tumors as sensitive or resistant and distinguished a clinically proven resistant tumor from other tumors. Conclusion This method defines conditions that allow ex vivo testing of individual tumor responses to anti-cancer drugs and therefore might improve personalization of breast cancer treatment