I- Introduction

II- Experiment

III- Parametric Degradation

IV- Mechanisms

V- Source Dependence

VI- Implications

VII- Summary

VIII- Acknowledgment

References

Abstract 

Irradiation of 2N5339 NPN Bipolar Junction Transistors with either 250-MeV protons or 10-keV X-rays shifts the input characteristics to lower values of VBE while degrading the current gain and drive current. The degradation is consistent with increased recombination in the neutral base and emitterbase depletion region. A decrease in collector current following proton irradiation suggests that recombination in the neutral base is significant. At a given ionizing dose, degradation is worse for proton irradiation than for X-ray irradiation due to the presence of displacement damage and a higher charge yield. A comparison of degradation produced by the two radiation sources suggests that ~40% of the excess base current resulting from 250-MeV proton irradiation is due to ionization damage. When compared with previous results for other devices, these results suggest that ionization-to-displacement damage ratios in bipolar devices may increase with proton energy in a way that is consistent with trends in charge yield and NIEL.

INTRODUCTION

THE current gain of bipolar junction transistors is important in satellite amplification applications such as radio transmitters and RF power generation [1]. Energetic protons in space degrade bipolar current gain by producing both ionization damage in the oxide overlying the emitter-base (E-B) junction and displacement damage in the semiconductor bulk [2]. In contrast, 10-keV X-rays produce only ionization damage, since the secondary electrons that they produce have energies below the displacement damage threshold [3]. Consistent with an approach for damage separation outlined in ASTM E1855-15 [4], Arutt, et al. have estimated the contributions of ionization damage to 4-MeV proton-induced degradation of bipolar devices from several technologies by comparing the proton responses to those of 10-keV X-rays [5], [6]. To date, however, ratios of ionization damage and displacement damage at larger proton energies, characteristic of radiation environments in low-earth orbits [7], have not been examined. In this work, the portion of proton-induced degradation due to ionization damage is estimated for a commercial bipolar transistor following irradiation with 250-MeV protons. The amount of ionization damage at the larger proton energy is greater than that reported for 4-MeV protons by a factor of more than two, suggesting that ionization-to-displacement damage ratios in bipolar devices may depend strongly on proton energy. The trend in damage ratios is consistent with the dependencies of charge yield and NIEL on proton energy. Mechanisms leading to current gain degradation through increased base recombination are reviewed. Differences in degradation due to radiation source type are related to the relative amounts of ionization damage and displacement damage accumulated in each case. Finally, implications for using proton irradiation to screen bipolar devices for displacement damage are discussed.

Abstract

We review recent advances in the DNA sequencing method based on measurements of transverse electrical currents. Device configurations proposed in the literature are classified according to whether the molecular fingerprints appear as the major (Mode I) or perturbing (Mode II) current signals. Scanning tunneling microscope and tunneling electrode gap configurations belong to the former category, while the nanochannels with or without an embedded nanopore belong to the latter. The molecular sensing mechanisms of Modes I and II roughly correspond to the electron tunneling and electrochemical gating, respectively. Special emphasis will be given on the computer simulation studies, which have been playing a critical role in the initiation and development of the field. We also highlight low-dimensional nanomaterials such as carbon nanotubes, graphene, and graphene nanoribbons that allow the novel Mode II approach. Finally, several issues in previous computational studies are discussed, which points to future research directions toward more reliable simulation of electrical current DNA sequencing devices.

Introduction

The sequencing of DNA not only has significant scientific implications in the context of deciphering the fundamental code of life but also represents an enormous opportunity to improve the well-being of humankind by ushering in a new era of personal or precision medicine (Mardis, 2011; Shendure and Aiden, 2012; Rabbani et al., 2014). A decade after the completion of the Human Genome Project in 2003, effort is now devoted into the development of next-generation DNA sequencing technologies that can meet the ‘$1000 genome’ goal set by National Institute of Health. In this endeavor, in contrast to the second-generation DNA sequencing technologies that still require polymerase chain reaction amplification and fluorescent labeling as in the first-generation counterpart, the newly-emerged third-generation DNA sequencing technologies propose single molecule detection based on changes in ionic or electrical currents

The problems associated with wastewater disposal have become an inevitable problem to the urban world due to the increase in human population and urbanization. The commonality of wastewater-related problems throughout coastal areas of the world is signifcant since these areas are inhabited by over 60% of the human population (Maruthi et al. 2012a, b; Satyanarayana et al. 2010). Consequently, domestic wastewater discharge is considered as signifcant threat to the coastal environments worldwide (Global Programme of Action 2001). Environmental efects associated with wastewater discharges are generally local with trans-boundary implications in some areas (Maruthi et al. 2012c, d, e). The adverse public health, environmental, socio-economic, food quality and security and esthetic impacts from wastewater contamination in coastal areas are well documented (Abbas et al. 2017; Danulat et al. 2002; WHO 2003). Contamination of the coastal water may result in changes in nutrient levels, abundance, biomass and diversity of organisms, bioaccumulation of organic and inorganic compounds and alteration of tropic interaction among species (Hossain et al. 2015, 2016; Singh et al. 2016; Hossain and Ismail 2015). Receiving water with high fushing capacity is able to dilute or eliminate most of the conventional pollutants, but persistent toxic compounds and long lived pathogens will always be troublesome.

Sources of water pollution and its consequences

The natural processes, like rock weathering and climate changes that can afect water quality (Hossain et al. 2017), are the key sources of water pollution. The sources of water pollution are categorized into two types: point and non-point (difuse) sources. Hossain et al. (2015, 2016), Singh et al. (2016), Hossain and Ismail 2015, Carpenter et al. (1998) and Duda (1993) portrayed that point sources are typically piped discharges from municipal wastewater treatment plants, industrial facilities, small packaged treatment plants, large urban and industrial storm water systems and residential straight piping. Non-point sources on the other hand include storm water runof from timber harvesting, agricultural lands, rural residential development, failing septic systems and mining. Nutrient enrichment of surface water, as the result of runof from agricultural land in particular, is the most challenging problem in environmental management.

The main function of mitochondria is the production of ATP in the process of oxidative phosphorylation. The main byproduct that is formed in the course of electron transport in the respiratory chain is superoxide anion radical. Superoxide emerges as a result of one-electron reduction of molecular oxygen in various parts of the respiratory chain, including Complex I (NADH: ubiquinone oxidoreductase), Complex II (succinate dehydrogenase), Complex III (ubiquinol: cytochrome oxidoreductase), and mitochondrial matrix dehydrogenases [Grivennikova and Vinogradov, 2013]. Subsequently, the superoxide gives rise to various reactive oxygen species (ROS). Normally, only 1-2% of the oxygen consumed by the cells are used for ROS formation in mitochondria (mtROS) [Turrens, 2003, Inoue et al., 2003]. Until recently, it was believed that mtROS predominantly play a destructive role causing cell damage and accelerating aging [Harman, 2003]. These views are exemplified by the ideas that are expressed in the work of Huang and co-workers [1997]. It was established that mice with a knockout of cytosolic CuZn-dependent superoxide dismutase gene are viable, while mice with a nonfunctional mitochondrial Mn-dependent superoxide dismutase gene do not survive. Recently, it has been established that mtROS formation is mandatory for the functioning of virtually all organs and tissues, being involved in numerous metabolic pathways and in the regulation of signaling processes [Dan Dunn et al., 2015]. Importantly, mtROS are essential for the functioning of the immune system. However, their influence may be either positive or negative, depending on the quantity of the mtROS involved. From the immunological viewpoint, the positive effects of mtROS are primarily based on their activating influence on antimicrobial immunity, while their negative effects, caused by their excessive production, result in the induction of autoinflammatory [van der Burgh and Boes, 2015] and autoimmune processes [Lee et al., 2016; Lood et al., 2016]. The formation of mtROS plays an important role in the development of the antiviral immunity including the production of proinflammatory cytokines by immune system cells [Kim et al., 2015]. This review is concerned with the analysis of the mtROS role in terms of antibacterial innate immunity.