Evanescently-coupled hybrid III-V/silicon laser based on DVS-BCB bonding

© 2014 IEEE. Controllable electrical breakdown of multiwall nanotubes (MWNTs) is studied utilizing the atomic force microscopy (AFM). Electrical breakdown has been known as the way to fundamentally understand the electrical properties of nanotubes and an approach to develop MWNT based transistors and sensors. Normally, electrical breakdown was known to be happened in the center of MWNT because of the thermal accumulation. However, considering the effect of thermal dissipation, the electrical breakdown could be mechanically controlled by an additional heat sink, which could be the substrate of MWNT device. Therefore, the electrical breakdown process is controllable through controlling Joule heating and thermal dissipation. In this research, we study the crucial factors that affect the electrical breakdown. The AFM based nano robot is used to measure the conductance distribution, and manipulate the three dimensional structure of MWNT in order to change the position of heat sink to control the location where electrical breakdown happened. The controllable electrical breakdown is an alternative approach for conducting bandgap engineering in nanodevice and fabricating high performance nano sensors and transistors.Link_to_subscribed_fulltex

Application of plants in remediation of contaminated sites

The concern for environmental protection has existed since the time of first human civilization. As society develops, the chain of changes during the natural flow of processes in ecosystems has been supplemented by a new link - pollutants. They have an effect on all other members of the ecosystem (changes may be visible immediately or harder to spot), which leads to an extremely complex relationship with nature. The values of some parameters of pollutants reached an alarmingly high level. The tendency to reduce the risk of air, soil, water, plant, and animal pollution to a tolerable limit, which would salvage the environment and most importantly human health, became a global problem. Heavy metals as pollutants have been an interest of researchers for their conduct, especially in forest ecosystems, which has been expressed in the previous year's more than ever. With its numerous toxic effects, heavy metals are endangering the existence of plant species that live in already contaminated environments. This is all an argument regarding the fight of modern society that the emission of polluted materials gets reduced in order to avoid multiple negative effects, which can endanger the existence of living organisms in general, as an argument for the continuation of numerous researches that are conducted in this area. The monitoring of heavy metals is of significant importance because their toxicity and accumulations are vital for the ecosystem. Polluted soils can be reduced and they can restore their function using physical, chemical, and biological techniques. Physical and chemical methods are very expensive and cause mainly irreversible changes, thus destroying biological variety. The biological recovery of contaminated soil represents an efficient method of reducing health risks for both mankind and the ecosystem.  For this purpose, biological indicators are used. Numerous researches have led to improvements of the initial idea about using plants as a remediation of the environment and the removal of different contaminants from contaminated medias into promising technologies of environmental protection under the title "Phytoremediation". This technology consists of the reduction of concentrations of polluted materials in polluted soils, water, or air. Plants have the ability to store, degrade, or eliminate metals, pesticides, solutions, explosives, and crude oils. Its derivatives and various other contaminants form mediums that contain them. This paper especially considers methods of the possibility of the usage and application of plants in restoring soil contaminated by heavy metals as well as other pollutants

The potential of different plant species for nickel accumulation

Contamination of the environment with toxic heavy metals is a mayor environmental problem. Aimed to find effective and economical attractive solutions for environment cleaning, scientists intensively evolve various phytoremediation techniques. Nickel is one of the essential micronutrients for plants, animals, and humans, but toxic at elevated concentrations. Also, it belongs to a group of heavy metals. In respect of the fact that Ni uptake relies upon plant species and that some of them show hyperaccumulation effects, the aim of our study was to analyse Ni concentration in certain plant species affected by Ni contamination of air and surface soil. Ni deposition in the air was below 60 mu g/m(2)/month, while Ni content in the soil was between 42 and 150 mu g/g. Average Ni content in plants ranged from 0. 1 to 5. 0 mu g/g. Regardless the analysed locality, the highest Ni (7.1 mu g/g) was obtained with the hogweed, whereas the lowest (4.5 mu g/g) with the vines. Ambrosia artemis folia and Taraxum officinale accumulated the greatest amounts of Ni (10. 72 and 10. 61 mu g/g, respectively). It may be concluded that the analysed plant species exhibit various phytoremediation potential for Ni under the same ecological conditions

Ocena stopnia zaawansowania miażdżycy u dzieci i młodzieży z cukrzycą typu 1

Introduction: To evaluate the degree of atherosclerosis in children and adolescents with type 1 diabetes and its correlation with risk factors, traditional and other, such as anti-oxidative capacity of circulating blood and level of lipid peroxidation. Material and methods: Forty children and adolescents with type 1 diabetes with mean age 13.7 years were compared with 20 age- and sex-matched healthy control subjects. Association of carotid artery intima-media thickness (cIMT) with different risk factors measured in children with type 1 diabetes was evaluated. Results: Mean carotid IMT was higher in subjects with diabetes (p < 0.01) and was strongly associated with total cholesterol with an odds ratio of 4.08 (p = 0.016), LDL-cholesterol with an odds ratio of 2.78 (p = 0.037), length of disease with an odds ratio of 1.87 (p = 0.007) and positive family history (first- and second-degree relatives) of diabetes and early CVD (heart attack and/or stroke before the age of 60 years) with an odds ratio of 6.8 (p = 0.007). Conclusions: We found significantly increased cIMT in the diabetic patients compared to the healthy control subjects. Risk factors for the development of atherosclerosis included higher total and LDL-cholesterol, higher systolic blood pressure, positive family history of diabetes and early CVD and longer diabetes duration. In spite of the documented increased oxidative stress, we failed to establish a correlation between the oxidative stress parameters and cIMT values. (Endokrynol Pol 2012; 63 (6): 414&#8211;419)Wstęp: Ocena stopnia zaawansowania miażdżycy u dzieci i młodzieży z cukrzycą typu 1 oraz jego korelacja z czynnikami ryzyka, tradycyjnymi i innymi, na przykład potencjałem antyoksydacyjnym krwi krążącej i poziomem peroksydacji lipidów. Materiał i metody: Porównano 40 dzieci i nastolatków z cukrzycą typu 1, średnia wieku 13,7 roku, z 20 zdrowymi osobnikami stanowiącymi grupę kontrolną odpowiednio dobranymi pod względem wieku i płci. Oceniano związek pomiędzy grubością kompleksu błony wewnętrznej i środkowej tętnic szyjnych (cIMT) a różnymi czynnikami ryzyka ocenianymi ilościowo u dzieci z cukrzycą typu 1. Wyniki: Średnia wartość cIMT była większa u pacjentów z cukrzycą (p < 0,01) i wykazywała silny związek ze stężeniem cholesterolu całkowitego [iloraz szans (OR) 4,08; p = 0,016], cholesterolem frakcji LDL (OR 2,77; p = 0,037), czasem trwania choroby (OR 1,87; p = 0,007) i dodatnim wywiadem rodzinnym (krewni pierwszego i drugiego stopnia) w kierunku cukrzycy i wczesnego występowania chorób układu krążenia (zawału serca i/lub udaru mózgu przed 60. rokiem życia) (OR 6,8; p = 0,007). Wnioski: Stwierdzono znamiennie podwyższoną wartość cIMT u pacjentów z cukrzycą w porównaniu ze zdrowymi osobnikami z grupy kontrolnej. Czynniki ryzyka rozwoju miażdżycy obejmowały podwyższone stężenie cholesterolu całkowitego i cholesterolu frakcji LDL, podwyższone skurczowe ciśnienie tętnicze, dodatni wywiad rodzinny w kierunku cukrzycy i wczesnego występowania chorób układu krążenia oraz dłuższy czas trwania cukrzycy. Pomimo udokumentowanego wzmożenia stresu oksydacyjnego nie udało się ustalić korelacji pomiędzy parametrami stresu oksydacyjnego a wartościami cIMT. (Endokrynol Pol 2012; 63 (6): 414&#8211;419

Laser sources on a heterogeneous III-V/silicon platform

The heterogeneous integration of III-V semiconductor lasers on a silicon waveguide platform using DVS-BCB adhesive bonding is reviewed. Both mW-level lasers and ultra-compact laser sources are discussed

Build-Up PMMA Plate Effect on Calibration of TLD Reader

The routine monitoring of the occupationally exposed individuals constitutes an integral part of radiation protection program implemented at the Vinca Institute of Nuclear Sciences (INNV). The Individual monitoring service (IMS) at the INNV, accredited according to quality standard EN ISO/IEC 17025, is using Harshaw 6600 Plus automatic reader and thermoluminescent dosimeters (TLD) from two manufacturers (Harshaw, RadPro international GmbH). Working procedures are implemented according to Technical Recommendations for Monitoring Individuals Occupationally Exposed to External Radiation, RP 160 (European Commission, 2009). Among general consideration, RP 160 is suggesting that routine calibration of dosimetry system should be performed taking into consideration secondary charged particle equilibrium. As TLD system in use at IMS INNV comprises of TLD reader and of TLD cards, this consideration should be applied in both cases: when the reader and the TLD cards are being calibrated. During reader calibration, secondary charged particle equilibrium can be ensured using build-up PMMA plate of certain thickness placed in front of dosimeters. In this paper, influence of the build-up plate on reader calibration is being analyzed. This influence is observed through changes in reader calibration factor (RCF). RCF values obtained during reader calibration procedure with and without 2 mm thick build-up plate are presented. Exposures of whole body TLDs placed on slab phantom were done with Cs-137 radiation source located at Secondary Standard Dosimetry Laboratory (SSDL) at INNV. TLDs from both manufacturers had 2 detectors for measuring the dose equivalent at the depths of 10 mm and 0.07 mm. TLD reader was calibrated to measure effective dose in terms of Hp(10) and local skin dose in terms of Hp(0.07). RCF values for detectors measuring Hp(10), from both manufacturers, when irradiated without the plate were around 5% higher than RCF values obtained when irradiations were done with the plate. Values of RCFs for detectors measuring Hp(0.07) were around 1% higher when the plate had not been used. As RCF value is inversely proportional to measured dose, reader calibration without build-up plate, in terms of Hp(10), would lead to underestimated dose values. The observed RCF deviation of Hp(0.07) detector is regarded as consequence of exposure conditions uncertainties. In conclusion, if a constant geometry and constant operational conditions of TLDs are achieved, the only part of the TLD system that is not stable for a long time period is the TLD reader. To avoid inaccurate results, RCF should be orderly checked and reader calibration should be done according to widely accepted standards, currently in effect.3rd International Conference on Radiation and Applications in Various Fields of Research (RAD), Jun 08-12, 2015, Budva, Montenegr

Build-Up PMMA Plate Effect on Calibration of TLD Reader

The routine monitoring of the occupationally exposed individuals constitutes an integral part of radiation protection program implemented at the Vinca Institute of Nuclear Sciences (INNV). The Individual monitoring service (IMS) at the INNV, accredited according to quality standard EN ISO/IEC 17025, is using Harshaw 6600 Plus automatic reader and thermoluminescent dosimeters (TLD) from two manufacturers (Harshaw, RadPro international GmbH). Working procedures are implemented according to Technical Recommendations for Monitoring Individuals Occupationally Exposed to External Radiation, RP 160 (European Commission, 2009). Among general consideration, RP 160 is suggesting that routine calibration of dosimetry system should be performed taking into consideration secondary charged particle equilibrium. As TLD system in use at IMS INNV comprises of TLD reader and of TLD cards, this consideration should be applied in both cases: when the reader and the TLD cards are being calibrated. During reader calibration, secondary charged particle equilibrium can be ensured using build-up PMMA plate of certain thickness placed in front of dosimeters. In this paper, influence of the build-up plate on reader calibration is being analyzed. This influence is observed through changes in reader calibration factor (RCF). RCF values obtained during reader calibration procedure with and without 2 mm thick build-up plate are presented. Exposures of whole body TLDs placed on slab phantom were done with Cs-137 radiation source located at Secondary Standard Dosimetry Laboratory (SSDL) at INNV. TLDs from both manufacturers had 2 detectors for measuring the dose equivalent at the depths of 10 mm and 0.07 mm. TLD reader was calibrated to measure effective dose in terms of Hp(10) and local skin dose in terms of Hp(0.07). RCF values for detectors measuring Hp(10), from both manufacturers, when irradiated without the plate were around 5% higher than RCF values obtained when irradiations were done with the plate. Values of RCFs for detectors measuring Hp(0.07) were around 1% higher when the plate had not been used. As RCF value is inversely proportional to measured dose, reader calibration without build-up plate, in terms of Hp(10), would lead to underestimated dose values. The observed RCF deviation of Hp(0.07) detector is regarded as consequence of exposure conditions uncertainties. In conclusion, if a constant geometry and constant operational conditions of TLDs are achieved, the only part of the TLD system that is not stable for a long time period is the TLD reader. To avoid inaccurate results, RCF should be orderly checked and reader calibration should be done according to widely accepted standards, currently in effect.3rd International Conference on Radiation and Applications in Various Fields of Research (RAD), Jun 08-12, 2015, Budva, Montenegr

Die-to-die adhesive bonding for evanescently-coupled photonic devices

Heterogeneous integration of III-V semiconductor materials on the SOI (silicon-on-insulator) platform is a promising method for fabrication of active photonic devices. It requires a reliable and robust bonding procedure that also enables an effective optical coupling between III-V layers and SOI waveguides. Molecular bonding is usually used for this purpose, but due to its strict requirements for contamination-free and smooth bonding surfaces, it might not be sufficiently robust for industrial-scale fabrication. As an alternative technique, in this paper we present an adhesive bonding procedure based on the use of DVS-BCB. We developed a die-to-die adhesive bonding procedure, resulting in less than 100nm-thick bonding layers thereby enabling evanescent optical coupling between III-V layers and silicon waveguides. The process shows very good robustness and bonding strength (breakdownshear stress of 2MPa). In perspective, we plan to scale-up the process to a multiple die-to-wafer bonding procedure which would be suitable for industrial-scale fabrication