Creation Of Tracks Research Articles

Transformation of the diamond surface with a thin iron coating during annealing and transport properties of the formed conductive layer

In our study, we annealed polycrystalline diamond films with nanometer-thick iron coatings. Based on analysis of X-ray photoelectron spectroscopy data the presence of two catalytic processes was suggested. One is the continuous absorption of sp3 carbon by iron nanoparticles with subsequent extrusion of the sp2 phase from the formed iron carbide, which leads to the creation of deep tracks into the diamond bulk that are filled with graphite stacks. The other process involves a thin layer of iron carbide on the surface and results in the creation of sp2 layers, which are made up of fused graphene-like patches and are oriented mainly along the surface of the diamond film. For the sample annealed at 800 °C for 1 h, the sp2 layers formed exhibit semi-metallic conductivity with quantum corrections caused by disorders. At the same time, no evidence of iron contribution in conductivity of the annealed Fe-coated film was detected, implying that upon transforming the diamond, iron moved quite deep into the bulk. In addition, the formed conductive layer on the diamond surface shows mechanical stability, ensuring the reproducibility of conductivity measurements even after six months of storage in air. The study has revealed the potential for targeted metal-assisted formation of sp2 carbon-based conducting pathways on diamond surfaces for electronic devices.

The Effect of 147 MeV 84Kr and 24.5 MeV 14N Ions Irradiation on the Optical Absorption, Luminescence, Raman Spectra and Surface of BaFBr Crystals

Today, BaFBr crystals activated by europium ions are used as detectors that store absorbed energy in metastable centers. In these materials, the image created by X-ray irradiation remains stable in the dark for long periods at room temperature. As a result, memory image plates are created, and they are extended to other types of ionizing radiation as well. Despite significant progress towards X-ray storage and readout of information, the mechanisms of these processes have not been fully identified to date, which has hindered the efficiency of this class of phosphors. In this study, using photoluminescence (PL), optical absorption (OA), Raman spectroscopy (RS), and atomic force microscopy (AFM), the luminescence of oxygen vacancy defects to BaFBr crystals irradiated with 147 MeV 84Kr and 24.5 MeV 14N ions at 300 K to fluences (1010–1014) ion/cm2 was investigated. BaFBr crystals were grown by the Shteber method on a special device. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed the presence of Ba, Br, F, and O. The effect of oxygen impurities present in the studied crystals was considered. The analysis of the complex PL band, depending on the fluence and type of ions, showed the formation of three types of oxygen vacancy defects. Macrodefects (tracks) and aggregates significantly influence the luminescence of oxygen vacancy defects. The creation of hillocks and tracks in BaFBr crystals irradiated with 147 MeV 84Kr ions is shown for the first time. Raman spectra analysis confirmed that BaFBr crystals were amorphized by 147 MeV 84Kr ions due to track overlap, in contrast to samples irradiated with 24.5 MeV 14N ions. Raman and absorption spectra demonstrated the formation of hole and electron aggregate centers upon swift heavy ions irradiation.

Development of Multifunctional Detection Robot for Roller Coaster Track.

Recent advances in roller coasters accelerate the creation of complex tracks to provide stimulation and excitement for humans. As the main load-bearing component, tracks are prone to damage such as loose connecting bolts, paint peeling, corroded sleeper welds, corroded butt welds, reduced track wall thickness and surface cracks under complex environments and long-term alternating loads. However, inspection of the roller coaster tracks, especially the high-altitude rolling tracks, is a crucial problem that traditional manual detection methods have difficulty solving. In addition, traditional inspection is labor-intensive, time-consuming, and provides only discrete information. Here, a concept of the multifunctional detection robot with a mechanical structure, electrical control system, camera, electromagnetic ultrasonic probes and an array of eddy current probes for detecting large roller coaster tracks is reported. By optimizing the design layout, integrating multiple systems and completing machine testing, the multifunctional roller coaster track detection robot exhibits outstanding performance in track appearance, thickness and crack detection. This study provides great potential for intelligent detection in amusement equipment, railcar, train and so on.

A quantitative approach to density-based clustering of flight trajectories for efficient air traffic noise simulations

The continuous growth of air traffic and increased availability of open source data has enabled the application of data-driven approaches for the prediction of noise contours around airports. Aiming at efficient noise simulations, this contribution proposes a framework for the probabilistic description of the air traffic around an airport. The methodology is based on using the density-based clustering algorithm OPTICS to cluster flight trajectories. The clustered trajectories serve as a basis for the creation of backbone and dispersion tracks, which, together with a prescribed number of flight operations per aircraft type, provide a probabilistic description of the air traffic to the noise simulations. A major focus is given to quantitatively assess the sensitivity of the OPTICS algorithm to different hyper-parameters to reduce the dimensionality of the problem. This framework is demonstrated utilizing a dataset of ADS-B trajectory data associated with flights approaching Hannover airport. Noise simulations based on the ECAC Doc. 29 best-practice method are conducted using SoundPLAN. A good agreement between noise contours is obtained when comparing simulations performed using the proposed framework and the full dataset while the computational time required decreased. Furthermore, this approach identifies most of the trajectory patterns with the least amount of outliers.

An integral method for assessing the impact of dredging on the ecological state of river water resources

The study is aimed at solving the urgent problem of the impact of dredging operations carried out in river channels on the hydroecological state of river sections as the most important water resource. Many different factors arising from man-made interventions radically change the hydrology and hydroecology of rift areas. Taking into account all kinds of changes during the design phase leads to both the creation of sustainable tracks and the minimum impact on the environment. The aim of the study is to develop an integral quantitative method for assessing dredging and channeling works on the hydroecological state of river sections. The proposed method is based on the formalization of influencing factors and an algorithm for their quantitative assessment. It has a number of properties that distinguish it from the calculations previously used for hydroecological assessment, describing the interaction of the channel, flow and technogenic systems, in particular, the ability to obtain integral quantitative data. The classification of factors is proposed: by the degree of the direction of impact, the size of the area of influence, by the time duration. The possibility of using this method to create artificial neural networks for the design of dredging is shown. The possibility of functioning of an artificial neural network of the perceptron type, consisting of several layers of neurons, has been demonstrated.

Monte Carlo simulation of the passage of γ-rays and α-particles in CsI

Theoretical and computational methods for simulating the creation of ionization tracks by fast ions in solids were applied to the passage of α-particles in CsI, an inorganic scintillator commonly used for radiation detection. The methods were implemented in a Monte Carlo program to simulate the interaction of α-particles, with incident energies of up to 1 MeV, with CsI. The simulations followed the fate of individual electron-hole pairs and included the formation of Frenkel pairs and thus allowed for a detailed description of the microscopic structure of ionization and defect tracks created by incident radiation. Simulations were also performed with γ-rays of the same energy to compare and contrast the ionization tracks obtained with both types of particles. Intrinsic properties such as the mean energy per electron-hole pair, Fano factor, maximum theoretical light yield, and spatial distributions of electron-hole pairs were computed for both α-particles and γ-rays. α-Particles created cylindrical tracks that were initially aligned with the incident direction and with initial radii of a few tens of nanometers, whereas γ-rays showed significant scattering, resulting in probability distributions with lower intensities and much greater radial extents.

(Invited) Three-dimensional Free-standing Assemblies of Electrodeposited Nanowires for Photoelectrochemical and Catalytical Applications

The implementation of metal and semiconductor nanostructures in devices for catalysis, sensing, and energy conversion requires an excellent control on geometry, crystallinity and composition of the individual nanostructures, as well as its successful assembly into 2-D and 3-D architectures. In particular, nanowire ensembles offer important advantages compared to planar films including e.g. larger surface area and surface to volume ratio, and better crystalline quality.Ion-track nanotechnology is a powerful technique to create templates for the controlled synthesis of such 3-D nanowire architectures. Etched ion-track membranes are fabricated in two separate process steps: (i) sequential irradiation of polymer foils from one or various directions with swift heavy ions resulting in the creation of tracks; (ii) converting the ion tracks into nanochannels by selective chemical etching. Channel density and orientation, as well as diameter and geometry are adjusted by the irradiation and etching conditions, respectively. Afterwards, by electrodeposition in the nanochannels and subsequent removal of the polymer template 3-D assemblies of nanowires are synthesized. Since the nanowires adopt the exact shape of the host channel, their diameter can be adjusted between ~15 nm and a few µm, and their length between ~1 and several tens of µm.In this talk, we will discuss the electrochemical deposition of Au1-xAgx, Cu, and Cu2O in interconnected nanochannel networks, the characterization of the resulting 3-D nanowire assemblies, and the investigation of their photoelectrochemical and catalytical properties.

Predicting hadron-specific damage from fast hadrons in crystals for calorimetry

Fast hadrons have been observed to cause a cumulative damage in Lead Tungstate and LYSO crystals. The underlying mechanism has been proven to be the creation of fission tracks, which act as scattering centres, thus reducing the light collection efficiency. For calorimetry applications in an environment where large, fast hadron fluences are anticipated, predictions about damage in crystals are of great importance for making an informed choice of technology. In the study presented here, simulations using the FLUKA package have been performed on Lead Tungstate, LYSO and Cerium Fluoride, and their results have been compared with measurements. The agreement that is found between simulation results and experimental measurements allows to conclude that the damage amplitude in a given material can be predicted with a precision that is sufficient to anticipate the damage expected during detector operation.

Influence of oxygen ion implantation on the free volume parameters and electrical conductivity of a polymer‐based bakelite RPC detector material

ABSTRACTWe have investigated the effect of ion implantation on structural modification and the electrical conductivity of Bakelite‐resistive plate chamber (RPC) detector material used in high energy physics experiments. Samples of Bakelite polymer were exposed to 100 keV and 150 keV oxygen ions in the fluence of 1012 to 1015 ions cm−2. Ion implantation induced microstructural changes have been studied using positron annihilation lifetime spectroscopy, X‐ray diffraction and Fourier transform infrared techniques. Positron lifetime parameters viz., o‐Ps lifetime and its intensity showed formation of radicals, secondary ions due to the creation of interior tracks by high‐energy ions followed by chain scission at lower fluence of 100 keV implantation. The decreased free volume size at 150 keV ion implantation is an indication of crosslinking and filling up of interior tracks by the implanted ions. Variation of ac conductivity with frequency obeys Jonscher power law at 100 keV and the conduction mechanism is explained by barrier hopping model. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44962.

Impact of environmental factors on PADC radon detector sensitivity during long term storage

A broad set of data on poly-allyl diglycol carbonate (PADC) exposure to various environmental conditions has been collected for a period of 1 year in order to study the aging effect on the sensitivity to radon detection. Aging is a phenomenon that occurs during long PADC storage resulting in a loss of sensitivity and/or creation of false tracks. Conditions under investigation were storages under pure nitrogen or air atmospheres, in water solutions of different pHs, in a range of temperatures, humidity and exposure to UV, gamma and neutron radiations.It was found that PADC strongly responds to some external conditions through physical changes in the polymer material; for example, etching of UV exposed detectors led to 10% loss of their thickness and the removal of the tracks layer.Performance of detectors was compared with a control that was the sensitivity of detectors from the same sheet at the time of primary calibration – within 1 month of each sheet being manufactured. Substantial difference in performance was found between storage under pure, dry nitrogen and in the presence of water. The former preserves PADC radon detection properties for the period of one year without noticeable change. The latter, on the other hand significantly reduces its performance even after 3 months’ storage.It was also established that storage under low temperature is not a suitable means to preserve PADC sensitivity to radon detection due to significant loss in the detector sensitivity.

Decomposition mechanism of indium oxide nanoparticles sandwiched between zinc oxide layers by energetic ions

Decomposition of indium oxide nanoparticles (IONPs) sandwiched between zinc oxide (ZnO) thin films by energetic ions is reported. Multi-layers thin films were deposited using RF magnetron sputtering at room temperature, consisting two thin indium oxide layers sandwiched between three ZnO layers. Films exhibit very high transparency in the visible region. A sharp near band edge absorption with exciton absorption peak in the film annealed at the highest temperature was also observed. The structural and optical properties reveal that the as-deposited films show the formation of IONPs around the interface, which further grow upon increasing in annealing temperature. However, irradiation induces the decomposition of IONPs for the possible formation of single phase indium doped ZnO (IZO). The mechanism of the decomposition of IONPs is understood by the creation of ion tracks in IO. The track radius (Re) of 5.9nm is calculated in the framework of thermal spike model. Therefore, the IONPs with diameter≤2Re decomposed or amorphized between the crystalline ZnO layers; while the IONPs with diameter>2Re show reduction in size by the electronic sputtering from the IONPs surface under the thermo-elastic effects.

STABILITY OF THE NEUTRON DOSE DETERMINATION ALGORITHM FOR PERSONAL NEUTRON DOSEMETERS AT DIFFERENT RADON GAS EXPOSURES.

Since 2008 the Paul Scherrer Institute (PSI) has been using a microscope-based automatic scanning system for assessing personal neutron doses with a dosemeter based on PADC. This scanning system, known as TASLImage, includes a comprehensive characterisation of tracks. The distributions of several specific track characteristics such as size, shape and optical density are compared with a reference set to discriminate tracks of alpha particles and non-track background. Due to the dosemeter design at PSI, it is anticipated that radon should not significantly contribute to the creation of additional tracks in the PADC detector. The present study tests the stability of the neutron dose determination algorithm of the personal neutron dosemeter system in operation at PSI at different radon gas exposures.

SUNY Global Health Institute: A cross-campus global health initiative

fall within the academic sector. The remaining 34% work for government, NGOs, private groups, and in other capacities. Going Forward: Ongoing challenges: 1) Differentiated learning for very diverse student body 2) Adding additional elective opportunities 3) Adapting curriculum to a rapidly changing field Unmet goals: None Future changes: Creation of tracks or optional lengthening of the program for students wanting or needing additional training. Funding: Initial funding for the program came partially from the University of California, San Francisco. We have received some scholarship funding from private foundations since that time. Abstract #: 02ETC005

Supercath Safety Clampcath buttonhole creation: Complication of catheter breakage

The creation of buttonhole tracks with Supercath Safety Clampcath is a novel and simple technique that allows dull fistula needle insertions with relative ease and diminished pain. As greater experience with this procedure develops, new issues arise for consideration. We report an unexpected complication of Supercath Safety Clampcath catheter breakage that may be due to physical distortions as a result of its location in the antecubital fossa just proximal to the elbow joint. We present a review of our experience and a framework for the safe ongoing use of this device for creation of buttonholes in fistula for hemodialysis.

Experimental impact features in Stardust aerogel: How track morphology reflects particle structure, composition, and density

Abstract– The Stardust collector shows diverse aerogel track shapes created by impacts of cometary dust. Tracks have been classified into three broad types (A, B, and C), based on relative dimensions of the elongate “stylus” (in Type A “carrots”) and broad “bulb” regions (Types B and C), with occurrence of smaller “styli” in Type B. From our experiments, using a diverse suite of projectile particles shot under Stardust cometary encounter conditions onto similar aerogel targets, we describe differences in impactor behavior and aerogel response resulting in the observed range of Stardust track shapes. We compare tracks made by mineral grains, natural and artificial aggregates of differing subgrain sizes, and diverse organic materials. Impacts of glasses and robust mineral grains generate elongate, narrow Type A tracks (as expected), but with differing levels of abrasion and lateral branch creation. Aggregate particles, both natural and artificial, of a wide range of compositions and volatile contents produce diverse Type B or C shapes. Creation of bulbous tracks is dependent upon impactor internal structure, grain size distribution, and strength, rather than overall grain density or content of volatile components. Nevertheless, pure organic particles do create Type C, or squat Type A* tracks, with length to width ratios dependent upon both specific organic composition and impactor grain size. From comparison with the published shape data for Stardust aerogel tracks, we conclude that the abundant larger Type B tracks on the Stardust collector represent impacts by particles similar to our carbonaceous chondrite meteorite powders.

Changes in seed dispersal processes and the potential for between‐patch connectivity for an arid land daisy

Dispersal is a major and critical process in population biology that has been particularly challenging to study. Animals can have major roles in seed dispersal even in species that do not appear specifically adapted to animal-aided dispersal. This can occur by two processes: direct movement of diaspores by animals and modification of landscape characteristics by animals in ways that greatly influence dispersal. We exploited the production of large, persistent dispersal structures (seed heads, henceforth) by Erodiophyllum elderi (Asteraceae), a daisy from arid Australia, to further understand secondary dispersal. Seed head dispersal on and off animal tracks in eight E. elderi patches was monitored for 9.5 months by periodically recording the location of marked seed heads. Sites were located inside a reserve that excludes sheep but not kangaroos, and in a nearby area with both kangaroos and sheep. The distance moved and likelihood of seed head movement was higher in areas with sheep, and especially along animal tracks. There was clear evidence that seed heads were channeled down animal tracks during large rainfall events. Seed head dispersal away from patches occurred to a limited extent via their physical contact with sheep and potentially via wind dispersal. Thus, the advantages of this study system allowed us to demonstrate the two postulated effects of herbivores on dispersal via direct movement of seed heads, and two distinct indirect effects through landscape modification by herbivores from the creation of animal tracks and the denudation of vegetation.

Use of the BioHole™ device for the creation of tunnel tracks for buttonhole cannulation of fistula for hemodialysis

Buttonhole cannulation is a method of cannulation of native arteriovenous fistulae traditionally practiced by self-cannulators. At St Michael's Hospital, this method has been modified to allow its use in problematic fistulae by multiple cannulators. In a busy dialysis unit, the need for a few specific cannulators to establish the tunnel tracks in combination with the variable dialysis schedules creates logistical challenges. A new method of creating tunnel tracks with the use of the BioHole™ device was evaluated. Buttonhole tracks were created in 12 patients using a peg of polycarbonated material with a holder (BioHole™ kit). The peg was inserted into the path left by the hemodialysis sharp needle following the index cannulation. Four of the 12 patients had an alternate access. Buttonhole tracks were successfully created in all the patients, albeit in 2 patients, the initial attempt to establish buttonhole tracks was aborted due to complications and the procedure was rescheduled. Compared with the modified buttonhole technique, pain on cannulation following track creation was significantly less in the BioHole™ group (P < 0.001). Ease of cannulation was significantly improved in the BioHole™ group (P<0.05) when compared with that in thrice-weekly patients using the modified buttonhole technique. Hemostasis postdialysis did not differ between the study groups. The use of the BioHole™ device is effective in the creation of tunnel tracks for buttonhole cannulation, is associated with less pain, and simplifies the logistics of arranging patient and nurses' schedules.

Impact of time and space evolution of ion tracks in nonvolatile memory cells approaching nanoscale

Swift heavy ions impacting on matter lose energy through the creation of dense tracks of charges. The study of the space and time evolution of energy exchange allows understanding the single event effects behavior in advanced microelectronic devices. In particular, the shrinking of minimum feature size of most advanced memory devices makes them very interesting test vehicles to study these effects since the device and the track dimensions are comparable; hence, measured effects are directly correlated with the time and space evolution of the energy release. In this work we are studying the time and space evolution of ion tracks by using advanced non volatile memories and Monte Carlo simulations. Experimental results are very well explained by the theoretical calculations.

The activity of an insectivorous bat Neoromicia nana on tracks in logged and unlogged forest in tropical Africa

AbstractLogging activities and the associated creation of roads and tracks can disturb and fragment forests, which may lead to a loss of forest‐dependent species and possibly favour nonforest generalists and edge species. The effects of such disturbance are poorly known for African insectivorous bats. We studied the activity patterns of insectivorous bats in a tropical African forest at Kibale National Park, Uganda, using an Anabat bat detector. The echolocation calls of the vespertilionid bat Neoromicia nana were the most frequently detected. This species was most active in the first 5 h after sunset with activity declining rapidly after midnight until sampling finished at 01:00 h. There was no difference in activity of N. nana levels between logged or undisturbed forest; however, this species exhibited higher levels of activity along the wide tracks running through the two forests than either 30 m off these tracks or along the narrow forest trails. The wing morphology and echolocation call of N. nana may be constraining it to flying in uncluttered space on the edge of the forest, penetrating mostly along wider tracks and roads. Further research (in particular radio‐telemetry) is required to test and validate these data.

Study of optical band gap and carbon cluster sizes formed in 100 MeV Si8+ and 145 MeV Ne6+ ions irradiated polypropylene polymer

A wide variety of material modifications in polymers have been studied by using ion irradiation techniques. Extensive research has focused on to Swift Heavy Ions (MeV’s energy), probably because of good controllability and the large penetration length in polymers. High energy ion irradiation tends to damage polymers significantly by electronic excitation and ionization. It may result into the creation of latent tracks and can also cause formation of radicals such as ablation, sputtering, chain scission and intermolecular cross-linking, creation of triple bonds and unsaturated bonds and loss volatile fragments. Polypropylene polymer films of thickness 50 μm were irradiated to the fluences of 1 × 1010, 3 × 1010, 1 × 1011, 3 × 1011, 6 × 1011 and 1 × 1012 ions/cm2 with Si8+ ions of 100 MeV energy from Pelletron accelerator at Inter University Accelerator Centre (IUAC), New Delhi and Ne6+ ions of 145 MeV to the fluences of 108, 1010, 1011, 1012 and 1013 ions/cm3 from Variable Energy Cyclotron Centre, Kolkata. Optical modifications were characterized by UV towards the red end of the spectrum with the increase of the fluence. Value of optical band gap Eg shows a decreasing trend with ion fluence irradiated with both kinds of ions. Cluster size N, the number of carbon atoms per conjugation length increases with increasing ion dose. Cluster size also increases with the increase of electronic stopping power.