Radiation compatibility of thin layer resistors in integrated technology

U radu se razmatra dejstvo nuklearnog i elektromagnetnog zračenja na tanke izolacione slojeve koji su presudni u odvajanju elektronskih komponenti i struktura u višeslojnim gusto pakovanim integrisanim kolima. Naime, smanjenje debljine aktivnih i pasivnih slojeva integrisanih kola čini iste veoma osetljivim na dejstvo jonizujućeg zračenja i pojave prenapona atmosferskog i komutacionog porekla. Paralelno sa proizvodnjom takvih elektronskih kola razvoj tehnologije je doveo do povećanja nuklearne i elektromagnetne kontaminacije životne sredine. Istovremena pojava tankih višeslojnih elektronskih kola i nuklearne kontaminacije rezultirala je sinergijom koja je ograničila dalju minimizaciju elektronskih komponenti i sklopova postavivši jasnu granicu do koje ona može da ide. U pogledu dejstva nuklearnog zračenja i prenapona posebno je nepoželjan efekat koji može da dovede do proboja tankih izolacionih struktura. Takav efekat dovodi do kratkog spajanja elektronskih sklopova i komponenata čime se u potpunosti uništava višeslojno gusto pakovano integrisano kolo kao i ukupan sistem u koji je to kolo ugrađeno. Posebno nepovoljna situacija je kada se dejstvom jonskog zračenja stvori veće oštećenje u izolacionom sloju koje onda probiju i prenaponi submilivoltnog intenziteta, tj. kada dođe do sinergije između mehanički razarajućeg dejstva jonskog zračenja i električnog razaranja brzih prenaponskih pojava. Da bi se dobila slika o pouzdanosti komercijalnih električnih višeslojno integrisanih elektronskih komponenti u polju jonskog zračenja u ovom radu se opredelilo za numericki eksperiment primenom metode Monte Karlo. Pri tome je izabran optimalan generator slučajnih brojeva i napravljen je model ispitujućeg višeslojnog integrisanog kola pogodan za primenu postavljenog numeričkog eksperimenta. Realni eksperiment, koji je lakše izvodljiv, je izbegnut pošto se njime dobija integralna radijaciona kompatibilnost, a ne i diferencijalna, kao u slučaju numeričkog eksperimenta. Monte Karlo simulacije transporta protona kroz tanke slojeve SiO2, AlN, Al2O3 i polikarbonata su pokazali da su navedeni slojevi imuni na prolazak protona sa energijama većim od ∼10 MeV. Nejonizujući gubici energije ovih visokoenergetskih protona su mali i oni prolaze kroz slojeve bez mnogo atomskog rasejavanja. U donjem delu istraženog opsega protonske energije (od 10 keV do 1 MeV), treba očekivati značajne gubitke jonizacije. Jonizacija i oštećenja uzrokovana pomeranjima usled prolaska protona mogu uticati na svojstva pomenutih izolatora i ugroziti njihovu pouzdanost u složenim sklopovima i uređajima. Tačkasti defekti, od kojih su neki donori nosača naelektrisanja, nastaju u ozračenim izolatorima kao rezultat pomeranja (dislokacije) atoma. Visoko reaktivni slobodni radikali koji se mogu pojaviti u ozračenom leksanu izazivaju cepanje lanca i/ili umrežavanje, što utiče na izolaciona svojstva polikarbonatnih slojeva.The doctoral dissertation discusses the effect of nuclear and electromagnetic radiation on thin insulating layers that are crucial in the separation of electronic components and structures in multilayer densely packed integrated circuits. The thickness reducing of the active and passive layers of integrated circuits makes them very sensitive to the effects of ionizing radiation and the occurrence of overvoltages of atmospheric and commutation origin. In parallel with the production of such electronic circuits, the development of technology has led to an increase in nuclear and electromagnetic environmental contamination. The simultaneous emergence of thin multilayer electronic circuits and nuclear contamination has resulted in synergies that have limited further minimization of electronic components and assemblies by setting a clear limit to which it can go. With regard to the effects of nuclear radiation and overvoltage, the effect that can lead to the breakthrough of thin insulating structures is particularly undesirable. Such an effect leads to a short circuit of electronic assemblies and components, which completely destroys the multilayer densely packed integrated circuit as well as the overall system in which the circuit is installed. A particularly unfavorable situation is when the action of ion radiation creates greater damage in the insulating layer, which then breakthrough even overvoltages of submilivolt intensity, ie. when there is a synergy between the mechanically destructive effect of ion radiation and the electrical destruction of rapid surges. In order to obtain a picture of the reliability of commercial electrical multilayer integrated electronic components in the field of ion radiation, in this doctoral dissertation we decided on a numerical experiment using the Monte Carlo method. In doing so, the optimal random number generator was chosen and a model of the test multilayer integrated circuit suitable for the application of the set numerical experiment was made. A real experiment, which is easier to perform, is avoided because it gives integral radiation compatibility, and not differential, as in the case of a numerical experiment. Monte Carlo simulations of proton transport through thin layers of SiO2, AlN, Al2O3 and polycarbonate have shown that the investigated layers are immune to the passage of protons with energies higher than ∼10 MeV. Nonionizing energy loss of these high energy protons is low, and they traverse the layers without much atomic displacement. In the lower part of the investigated proton energy range (from 10 keV to 1 MeV), however, substantial ionization losses are to be expected. Ionization and displacement damage produced by protons could influence the properties of these insulators and compromise their reliability within complex structures and devices. Point defects, some of which are charge-carrier donors, arise in irradiated insulators as a result of atomic displacements. Highly reactive free radicals that can appear in irradiated lexan cause chain scission and/or cross-linking, which then affects the insulating properties of polycarbonate layers

Simulation-based calculations of the proton dose in phase change memory cells

Monte Carlo simulations of proton irradiation on phase change memory cells were conducted and the proton dose, in both the whole memory cell and in its active layer, calculated. The memory cell was modeled by a multi-layer stack consisting of two TiW electrodes and ZnS-SiO2 films as insulators surrounding the active region. Materials considered for the active region were Ge2Sb2Te5, AgSbSe2, and Si2Sb2Te5. The effects of exposing phase change memory cells to proton beams were investigated for various thicknesses of phase change materials and different proton energies. Radiation-induced changes in the investigated memory cells are presented, including the accumulation of atomic displacements and the thermal heating of the active region. Possible effects of these changes on cell operation are discussed. [Projekat Ministarstva nauke Republike Srbije, br. 171007

Possibility of achieving an acceptable response rate of gas-filled surge arresters by substitution of alpha radiation sources by selection of electrode material and the electrode surface topography

The possibility of substituting the usage of a radioactive a-source to improve the characteristics of the gas surge arrester is considered in this paper. The solution to this problem is sought in the engineering of the characteristics by applying different electrode materials and varying electrode surface topography. Materials that differ in the output work value were examined. The electrode surface topographies were either polished, or with engraved regular spikes, or with polished cavities. The paper is mostly experimental in nature. The experiments were performed under well-controlled laboratory conditions. The measurement uncertainty of the experimental procedure was satisfactory. Experimental results were processed by sophisticated statistical methods of low statistical unreliability. The obtained results show that it is possible to avoid the installation of a radioactive source in the gas surge arresters and how it should be done. In this way, a possible contamination of the natural environment with extremely dangerous alpha - radioactive sources would be avoided

Establishment and in-house validation of stem-loop rt pcr method for microrna398 expression analysis

MicroRNAs (miRNAs) belong to the class of small non-coding RNAs which have important roles throughout development as well as in plant response to diverse environmental stresses. Some of plant miRNAs are essential for regulation and maintenance of nutritive homeostasis when nutrients are in excess or shortage comparing to optimal concentration for certain plant species. Better understanding of miRNAs functions implies development of efficient technology for profiling their gene expression. We set out to establish validate the methodology for miRNA gene expression analysis in cucumber grown under suboptimal mineral nutrient regimes, including iron deficiency. Reverse transcription by "stem-loop" primers in combination with Real time PCR method is one of potential approaches for quantification of miRNA gene expression. In this paper we presented a method for "stem loop" primer design specific for miR398, as well as reaction optimization and determination of Real time PCR efficiency. Proving the accuracy of this method was imperative as "stem loop" RT which consider separate transcription of target and endogenous control. The method was verified by comparison of the obtained data with results of miR398 expression achieved using a commercial kit based on simultaneous conversion of all RNAs in cDNAs

Soliton formation by decelerating interacting Airy beams

We demonstrate a new type of soliton formation arising from the interaction of multiple two-dimensional Airy beams in a nonlinear medium. While in linear regime, interference effects of two or four spatially displaced Airy beams lead to accelerated intensity structures that can be used for optical induction of novel light guiding refractive index structures, the nonlinear cross-interaction between the Airy beams decelerates their bending and enables the formation of straight propagating solitary states. Our experimental results represent an intriguing combination of two fundamental effects, accelerated optical beams and nonlinearity, together enable novel mechanisms of soliton formation that will find applications in all-optical light localization and switching architectures. Our experimental results are supported by corresponding numerical simulations

Silicon mitigates oxidative stress in cucumber at copper excess

Beneficial effects of silicon (Si) are well demonstrated for many crop species, although its essentiality is SI still not proven. Some mechanisms of Si-mediated alleviation of different stresses in plants have been proposed in the literature, however the molecular bases of these mechanisms are poorly understood. Metal toxicity It, considered as an important environmental problem in many agricultural soils worldwide. Copper (Cu) is an essential microelement for plant growth and development. As a redox-active transition metal, Cu is a cofactor in many proteins involved in electron transfer chains including respiration and photosynthesis. However, in excess Cu can induce oxidative stress via several proposed mechanisms, including direct generation of ro active oxygen species (ROS) through the Fenton reaction. The aim of th is study was to elucidate the molecular mechanism of Si-mediated alleviation of oxidative stress caused by excess Cu in cucumber. Hydroponically grown plants were subjected to different Cu concentrations, with or without Si supply. The high Cu-treated plants showed higher biomass and better root growth when Si was applied. The parameters of oxidative stress lipid peroxidation, total phenolics and tissue Cu concentrations were measured. Expressions of the genes involved in antioxidative defense and biosynthesis of phenolics were in accordance with the biochemical findings, clearly demonstrating the multiple role of Si in alleviation the harmful effects of ROS in cucumber

Cell wall localization of the aspartic proteinase from buckwheat (FeAPL1) over-expressed in tobacco BY-2 cells

The recombinant aspartic proteinase-like protein (FeAPL1-His6) was overexpressed in the tobacco BY-2 cell line and the expected pepstatin A-sensitive enzymatic activity was confirmed at pH 3.0. Immunocytochemistry and protein gel blot analysis of the transformed BY-2 cells and their protoplasts showed extracellular localization of rFeAPL1-His6 in the cell wall. Based on the obtained results, potential functions of FeAPL1 are discussed

Radiation compatibility of thin layer resistors in integrated technology

U radu se razmatra dejstvo nuklearnog i elektromagnetnog zračenja na tanke izolacione slojeve koji su presudni u odvajanju elektronskih komponenti i struktura u višeslojnim gusto pakovanim integrisanim kolima. Naime, smanjenje debljine aktivnih i pasivnih slojeva integrisanih kola čini iste veoma osetljivim na dejstvo jonizujućeg zračenja i pojave prenapona atmosferskog i komutacionog porekla. Paralelno sa proizvodnjom takvih elektronskih kola razvoj tehnologije je doveo do povećanja nuklearne i elektromagnetne kontaminacije životne sredine. Istovremena pojava tankih višeslojnih elektronskih kola i nuklearne kontaminacije rezultirala je sinergijom koja je ograničila dalju minimizaciju elektronskih komponenti i sklopova postavivši jasnu granicu do koje ona može da ide. U pogledu dejstva nuklearnog zračenja i prenapona posebno je nepoželjan efekat koji može da dovede do proboja tankih izolacionih struktura. Takav efekat dovodi do kratkog spajanja elektronskih sklopova i komponenata čime se u potpunosti uništava višeslojno gusto pakovano integrisano kolo kao i ukupan sistem u koji je to kolo ugrađeno. Posebno nepovoljna situacija je kada se dejstvom jonskog zračenja stvori veće oštećenje u izolacionom sloju koje onda probiju i prenaponi submilivoltnog intenziteta, tj. kada dođe do sinergije između mehanički razarajućeg dejstva jonskog zračenja i električnog razaranja brzih prenaponskih pojava. Da bi se dobila slika o pouzdanosti komercijalnih električnih višeslojno integrisanih elektronskih komponenti u polju jonskog zračenja u ovom radu se opredelilo za numericki eksperiment primenom metode Monte Karlo. Pri tome je izabran optimalan generator slučajnih brojeva i napravljen je model ispitujućeg višeslojnog integrisanog kola pogodan za primenu postavljenog numeričkog eksperimenta. Realni eksperiment, koji je lakše izvodljiv, je izbegnut pošto se njime dobija integralna radijaciona kompatibilnost, a ne i diferencijalna, kao u slučaju numeričkog eksperimenta. Monte Karlo simulacije transporta protona kroz tanke slojeve SiO2, AlN, Al2O3 i polikarbonata su pokazali da su navedeni slojevi imuni na prolazak protona sa energijama većim od ∼10 MeV. Nejonizujući gubici energije ovih visokoenergetskih protona su mali i oni prolaze kroz slojeve bez mnogo atomskog rasejavanja. U donjem delu istraženog opsega protonske energije (od 10 keV do 1 MeV), treba očekivati značajne gubitke jonizacije. Jonizacija i oštećenja uzrokovana pomeranjima usled prolaska protona mogu uticati na svojstva pomenutih izolatora i ugroziti njihovu pouzdanost u složenim sklopovima i uređajima. Tačkasti defekti, od kojih su neki donori nosača naelektrisanja, nastaju u ozračenim izolatorima kao rezultat pomeranja (dislokacije) atoma. Visoko reaktivni slobodni radikali koji se mogu pojaviti u ozračenom leksanu izazivaju cepanje lanca i/ili umrežavanje, što utiče na izolaciona svojstva polikarbonatnih slojeva.The doctoral dissertation discusses the effect of nuclear and electromagnetic radiation on thin insulating layers that are crucial in the separation of electronic components and structures in multilayer densely packed integrated circuits. The thickness reducing of the active and passive layers of integrated circuits makes them very sensitive to the effects of ionizing radiation and the occurrence of overvoltages of atmospheric and commutation origin. In parallel with the production of such electronic circuits, the development of technology has led to an increase in nuclear and electromagnetic environmental contamination. The simultaneous emergence of thin multilayer electronic circuits and nuclear contamination has resulted in synergies that have limited further minimization of electronic components and assemblies by setting a clear limit to which it can go. With regard to the effects of nuclear radiation and overvoltage, the effect that can lead to the breakthrough of thin insulating structures is particularly undesirable. Such an effect leads to a short circuit of electronic assemblies and components, which completely destroys the multilayer densely packed integrated circuit as well as the overall system in which the circuit is installed. A particularly unfavorable situation is when the action of ion radiation creates greater damage in the insulating layer, which then breakthrough even overvoltages of submilivolt intensity, ie. when there is a synergy between the mechanically destructive effect of ion radiation and the electrical destruction of rapid surges. In order to obtain a picture of the reliability of commercial electrical multilayer integrated electronic components in the field of ion radiation, in this doctoral dissertation we decided on a numerical experiment using the Monte Carlo method. In doing so, the optimal random number generator was chosen and a model of the test multilayer integrated circuit suitable for the application of the set numerical experiment was made. A real experiment, which is easier to perform, is avoided because it gives integral radiation compatibility, and not differential, as in the case of a numerical experiment. Monte Carlo simulations of proton transport through thin layers of SiO2, AlN, Al2O3 and polycarbonate have shown that the investigated layers are immune to the passage of protons with energies higher than ∼10 MeV. Nonionizing energy loss of these high energy protons is low, and they traverse the layers without much atomic displacement. In the lower part of the investigated proton energy range (from 10 keV to 1 MeV), however, substantial ionization losses are to be expected. Ionization and displacement damage produced by protons could influence the properties of these insulators and compromise their reliability within complex structures and devices. Point defects, some of which are charge-carrier donors, arise in irradiated insulators as a result of atomic displacements. Highly reactive free radicals that can appear in irradiated lexan cause chain scission and/or cross-linking, which then affects the insulating properties of polycarbonate layers

Anomalous lateral beam shift and total absorption due to excitation of surface waves in materials with negative refraction

We studied electromagnetic beam reflection from layered structures that include materials with negative refraction. Excitation of leaky surface waves leads to the formation of anomalous lateral shifts in the reflected beams with single or double peak structures. The presence of reasonable losses within material with negative refraction, besides significant influence on manifestation of the giant lateral shifts, can lead to their total suppression and anomalously high absorption of the incident radiation. If, in addition to the resonant excitation of leaky surface waves, radiation inflow exactly compensates their irreversible damping, total absorption of the incoming radiation can be achieved for moderately wide beams.

Astrocytes in the tempest of multiple sclerosis

Astrocytes are the most abundant cell population within the CNS of mammals. Their glial role is perfectly performed in the healthy CNS as they support functions of neurons. The omnipresence of astrocytes throughout the white and grey matter and their intimate relation with blood vessels of the CNS, as well as numerous immunity-related actions that these cells are capable of, imply that astrocytes should have a prominent role in neuroinflammatory disorders, such as multiple sclerosis (MS). The role of astrocytes in MS is rather ambiguous, as they have the capacity to both stimulate and restrain neuroinflammation and tissue destruction. In this paper we present some of the proved and the proposed functions of astrocytes in neuroinflammation and discuss the effect of MS therapeutics on astrocytes. (C) 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.Serbian Ministry of Science and Technological Development [ON173035, ON175038