| 1. |
- Andreou, Charalambos M., et al.
(författare)
-
Low-Power, Subthreshold Reference Circuits for the Space Environment : Evaluated with -rays, X-rays, Protons and Heavy Ions
- 2019
-
Ingår i: Electronics. - : MDPI. - 2079-9292. ; 8:5
-
Tidskriftsartikel (refereegranskat)abstract
- The radiation tolerance of subthreshold reference circuits for space microelectronics is presented. The assessment is supported by measured results of total ionization dose and single event transient radiation-induced effects under -rays, X-rays, protons and heavy ions (silicon, krypton and xenon). A high total irradiation dose with different radiation sources was used to evaluate the proposed topologies for a wide range of applications operating in harsh environments similar to the space environment. The proposed custom designed integrated circuits (IC) circuits utilize only CMOS transistors, operating in the subthreshold regime, and poly-silicon resistors without using any external components such as compensation capacitors. The circuits are radiation hardened by design (RHBD) and they were fabricated using TowerJazz Semiconductor's 0.18 m standard CMOS technology. The proposed voltage references are shown to be suitable for high-precision and low-power space applications. It is demonstrated that radiation hardened microelectronics operating in subthreshold regime are promising candidates for significantly reducing the size and cost of space missions due to reduced energy requirements.
|
|
| 2. |
- Andreou, Charalambos M., et al.
(författare)
-
Single Event Transients and Pulse Quenching Effects in Bandgap Reference Topologies for Space Applications
- 2016
-
Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 63:6, s. 2950-2961
-
Tidskriftsartikel (refereegranskat)abstract
- An architectural performance comparison of bandgap voltage reference variants, designed in a 0.18 mu m CMOS process, is performed with respect to single event transients. These are commonly induced in microelectronics in the space radiation environment. Heavy ion tests (Silicon, Krypton, Xenon) are used to explore the analog single-event transients and have revealed pulse quenching mechanisms in analogue circuits. The different topologies are compared, in terms of cross-section, pulse duration and pulse amplitude. The measured results, and the explanations behind the findings, reveal important guidelines for designing analog integrated circuits, which are intended for space applications. The paper includes an analysis on how pulse quenching occurs within the indispensable current mirror, which is used in every analog circuit.
|
|
| 3. |
- Gonzalez-Arto, Marta, et al.
(författare)
-
Melatonin receptors MT1 and MT2 are expressed in spermatozoa from several seasonal and nonseasonal breeder species
- 2016
-
Ingår i: Theriogenology. - : ELSEVIER SCIENCE INC. - 0093-691X .- 1879-3231. ; 86:8, s. 1958-1968
-
Tidskriftsartikel (refereegranskat)abstract
- Melatonin is a ubiquitous and multipurpose molecule, and one of its roles is to regulate reproduction in some seasonal mammals. Our group has previously reported the variation in the melatonin levels in ram seminal plasma along the year and identified MT1 and MT2 receptors in ram spermatozoa. The objective of this study was to elucidate whether the presence of melatonin receptors (MT1 and MT2) in the sperm plasma membrane, and melatonin in the seminal plasma is related to seasonal breeding. For this purpose, the presence of melatonin receptors and tseasonal breeder (epididymal spermatozoa); bull as a conventional nonseasonhe levels of melatonin in seminal plasma have been examined in several species: donkey and stallion as long-day breeders; red deer as a wild, short-day, highly al breeder; boar as a seasonal breeder, under management techniques; and dog as possible a seasonal breeder not regulated by melatonin. We have detected measurable levels of melatonin in the seminal plasma of all ejaculated semen samples (from donkey, stallion, boar, bull, and dog). Also, and for the first time, we have demonstrated the presence of MT1 and MT2 melatonin receptors in the spermatozoa of all these species, regardless their type of reproduction or sperm source (ejaculated or epididymal), using indirect immunofluorescence techniques and Western blotting. Our findings suggest that melatonin and melatonin receptors may be universally distributed in the reproductive system of mammals and that the sperm melatonin receptors cells may not be necessarily related with seasonal reproduction. Furthermore, the presence of MT1 at the cytoplasmic droplet in immature ejaculated stallion spermatozoa found in one sample and epididymal red deer spermatozoa suggests that melatonin may be involved in specific functions during spermatogenesis and sperm maturation, like protecting spermatozoa from oxidative damage, this activity being mediated through these receptors. (C) 2016 Elsevier Inc. All rights reserved.
|
|
