Contributors: Belmes, Kimberley B.
... UV bursts are compact brightenings in active regions that appear in UV images. They are identified through three spectroscopic features: (1) broadening and intensification of NUV/FUV emission lines, (2) the presence of optically thin Si IV emission, and (3) the presence of absorption features from cool metallic ions. Properties (2) and (3) imply that bursts exist at transition region temperatures (≥ 80,000 K) but are located in the cooler lower chromosphere (~ 5,000 K). Their energetic and dynamical properties remain poorly constrained. Improving our understanding of this phenomena could help us further constrain the energetic and dynamical properties of the chromosphere, as well as give us insight into whether or not UV bursts contribute to chromospheric and/or coronal heating. We analyzed the time evolution of UV bursts using spectral data from the Interface Region Imaging Spectrograph (IRIS). We inspected Si IV 1393.8 Å line profiles for Ni II 1393.3 Å absorption features to look for signs of heating. Weakening of absorption features over time could indicate heating of the cool ions above the burst, implying that thermal energy from the burst could rapidly conduct upward through the chromosphere. To detect the spectral profiles corresponding to bursts, we applied a four-parameter Gaussian fit to every profile in each observation and took cuts in parameter space to isolate the bursts. We then manually reviewed the remaining profiles by looking for a statistically significant appearance of Ni II 1393.3 Å absorption. We quantified these absorption features by normalizing the Si IV 1393.8 Å emission profiles and measuring the maximum fractional extinction in each. Our preliminary results indicate that Ni II 1393.3 Å absorption may undergo a cycle of strengthening and weakening throughout a burst’s lifetime. However, further investigation is needed for confirmation.
Contributors: King, Carson
... A coronal dimming is an event that takes place in the sun’s atmosphere, in which a patch of bright plasma seemingly disappears leaving a dark spot. These events are often associated with other solar phenomena such as flares and coronal mass ejections. Over the lifetimes of the SDO/AIA and Hinode/XRT telescopes many of these dimmings have been observed, however very few have been studied using XRT data. For this project one event was selected, and the goal was to measure how the area of the dimming region behaved over time in relation to other events in the area. In doing this, a new objective method for determining a threshold between the dimming region and the surrounding area was developed which can now be used to analyze the area of almost any dimming region. After comparing the region’s behavior over multiple wavelengths, our results support the common theory that these dimmings are caused by an evacuation of plasma due to opening magnetic field lines, rather than a sudden temperature change.
Contributors: Georgiadi Alexander et al., Androsov Alexey, Rossi Angelo and Unnithan Vikram, Chetverova Antonina et al., Reuter Balthasar and Aizinger Vadym, Koch Boris, Flores Hauke et al., Luneva Maria et al., Koldunov Nikolay, Hellmann Sebastian et al.
... Workshop ''East Siberian Shelf: observations, data analysis, modelling efforts", LenaDNM project, summary 7-9 of Dec, 2016
Development of Real-Time Image Stabilization and Control Systems for an Airborne Infrared Spectrometer
Contributors: Fedeler, Samuel
... The total solar eclipse of August 21, 2017 offers a unique opportunity for study of the infrared solar corona. The Airborne Infrared Spectrometer (AIR-Spec), currently under development, is an infrared telescope and spectrometer that will search for several magnetically sensitive coronal emission lines between 1.4 and 4 micrometers. This instrument will be the first to observe several of these lines, and the measurement campaign will determine whether any lines may be useful for future direct observations of the coronal magnetic field. AIR-Spec will be mounted on an NSF/NCAR Gulfstream V jet and will observe the eclipse from an altitude greater than 14.9 km, above the bulk of IR-absorbing atmospheric water vapor. To ensure that the images taken for analysis have adequate spatial resolution, the AIR-Spec line-of-sight must be stabilized to 2 arc-seconds over a 1 second exposure time. Image stabilization is achieved by using a fiber-optic gyroscope to measure aircraft rotation and a fast-steering mirror to adjust the line-of-sight accordingly. The stabilization algorithm runs in a programmable automation controller, which interfaces with the gyroscope and mirror. Software was developed to implement the stabilization algorithm in the controller and to integrate the controller with a user interface, allowing for data display and logging, user guided attitude calibration, and manual control of the fast-steering mirror. This software is currently being used in lab testing and will be operational during test flights in Fall 2016 and Spring 2017 and the eclipse flight in Summer 2017. The current system stabilizes images to 2 arc-seconds in 60 percent of 1 second camera exposures.
Contributors: Rimple, Remington
... Coronal Mass Ejections, or CMEs, are solar events that eject plasma and magnetic flux into interplanetary space. Contemporary sources have noted that the onset of CMEs are caused by some instability of the coronal magnetic field, and further allows heating of plasma upon expansion. Additionally, plasma that leaves the lower solar corona does not remain in ionization equilibrium due to the rapid expansion of plasma. We investigate the evolution of charge states of CME plasma using non-equilibrium ionization (NEI) modeling. These NEI models include radiative cooling and serve as baseline studies for special cases where no heat is being added to the plasma. Each of the simulated CMEs have initial conditions characteristic of active regions. Various function inputs, such as initial temperature, density and final velocity, allow us to examine the influence of certain parameters on the charge state evolution. The results of our project show that plasma originating from active regions display charge state evolutions substantially dependent on initial density and temperature. The CMEs starting with higher plasma density often show an abundance of lower charge states above the freeze-in height. Simulations starting from higher temperatures often show abundance peaks at charge states with closed electron shells.
The interaction of actinide and lanthanide ions with hemoglobin and its relevance to human and environmental toxicology
Contributors: Amit Kumar, Manjoor Ali, Raghumani S. Ningthoujam, Pallavi Gaikwad, Mukesh Kumar, Bimalendu B. Nath, Badri N. Pandey
... Due to increasing use of lanthanides/actinides in nuclear and civil applications, understanding the impact of these metal ions on human health and environment is a growing concern. Hemoglobin (Hb), which occurs in all the kingdom of living organism, is the most abundant protein in human blood. In present study, effect of lanthanides and actinides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] on the structure and function of Hb has been investigated. Results showed that these metal ions, except Ce(IV) interacted with carbonyl and amide groups of Hb, which resulted in the loss of its alpha-helix conformation. However, beyond 75μM, these ions affected heme moiety. Metal–heme interaction was found to affect oxygen-binding of Hb, which seems to be governed by their closeness with the charge-to-ionic-radius ratio of iron(III). Consistently, Ce(IV) being closest to iron(III), exhibited a greater effect on heme. Binding constant and binding stoichiometry of Th(IV) were higher than that of U(VI). Experiments using aquatic midge Chironomus (possessing human homologous Hb) and human blood, further validated metal–Hb interaction and associated toxicity. Thus, present study provides a biochemical basis to understand the actinide/lanthanide-induced interference in heme, which may have significant implications for the medical and environmental management of lanthanides/actinides toxicity.
Contributors: Dongjie Jiang, Nathan J. Bechle, Chad M. Landis, Stelios Kyriakides
... Experiment and analysis are used to investigate the buckling and recovery of pseudoelastic NiTi tubes with a diameter-to-thickness ratio of 23.6 under compression and the associated energy absorption. At a stress level corresponding to the onset of transformation to martensite, the tube initially buckles into a periodic axisymmetric wrinkling mode. The wrinkled structure remains stable despite the loss in stiffness, but at larger strain levels wrinkling gives way to an unstable non-axisymmetric buckling mode, characterized by three circumferential waves. With the load decreasing, this mode localizes first into a single lobe followed progressively by others. Unlike elastoplastic material behavior, transformation terminates into a stiff, saturation-type response with the linear elastic modulus of the M-phase. This stiffening of the material limits the growth of deformation in the mode-3 lobes preventing them from folding up. As a consequence, this progressive collapse occurs at a much higher stress level relative to that at the onset of collapse, than in concertina folding observed in typical structural metal energy absorbers. Even more importantly, on unloading the material transforms back to the A-phase resulting in recovery of deformation, erasure of the buckles, and a nearly closed hysteresis. The buckling and recovery phenomena are simulated numerically using a finite element model coupled to a J2-type nonlinear kinematic hardening model. The model is customized to the primarily compressive stress state of the problem at hand and is calibrated to the compressive hysteresis of the material. The analysis captures the onset of wrinkling, the switch to mode-3, and its localization first into a single lobe followed by a second and subsequent ones. The recovery on unloading is also reproduced by the analysis resulting in a completely closed hysteresis. Idealizations made in the present version of the constitutive model resulted in an unloading stress that is at a higher level than that observed in the experiment. Despite this discrepancy, the results demonstrate the overall veracity of the constitutive model developed.
A magnetic-based dispersive micro-solid-phase extraction method using the metal-organic framework HKUST-1 and ultra-high-performance liquid chromatography with fluorescence detection for determining polycyclic aromatic hydrocarbons in waters and fruit tea infusions
Contributors: Priscilla Rocío-Bautista, Verónica Pino, Juan H. Ayala, Jorge Pasán, Catalina Ruiz-Pérez, Ana M. Afonso
... A hybrid material composed by the metal-organic framework (MOF) HKUST-1 and Fe3O4 magnetic nanoparticles (MNPs) has been synthetized in a quite simple manner, characterized, and used in a magnetic-assisted dispersive micro-solid-phase extraction (M-d-μSPE) method in combination with ultra-high-performance liquid chromatography (UHPLC) and fluorescence detection (FD). The application was devoted to the determination of 8 heavy polycyclic aromatic hydrocarbons (PAHs) in different aqueous samples, specifically tap water, wastewaters, and fruit tea infusion samples. The overall M-d-μSPE-UHPLC-FD method was optimized and validated. The method is characterized by: its simplicity in both the preparation of the hybrid material (simple mixing) and the magnetic-assisted approach (∼10min extraction time), the use of low sorbent amounts (20mg of HKUST-1 and 5mg of Fe3O4 MNPs), and the low organic solvent consumption in the overall M-d-μSPE-UHPLC-FD method (1.5mL of acetonitrile in the M-d-μSPE method and 2.8mL of acetonitrile in the UHPLC-FD run). The resulting method has high sensitivity, with LODs down to 0.8ngL−1; adequate intermediate precision, with relative standard deviation values (RSD) always lower than 6.3% (being the range 5.9–9.0% in tap water for a spiked level of 45ngL−1, 6.1–14% in wastewaters for a spiked level of 45ngL−1, and 7.2–17% in fruit tea infusion samples for a spiked level of 45ngL−1); and adequate relative recoveries, with average values of 82% in tap water, and 94% and 75% in wastewater and fruit tea infusion samples, respectively, if using the proper matrix-matched calibration.
Contributors: Kathryn Grandfield, Ralf-Peter Herber, Ling Chen, Sabra Djomehri, Caleb Tam, Ji-Hyun Lee, Evan Brown, Wood R. Woolwine III, Don Curtis, Mark Ryder
... The objective of this study was to investigate the effect of mechanical strain by mapping physicochemical properties at periodontal ligament (PDL)–bone and PDL–cementum attachment sites and within the tissues per se.
Contributors: Diego Lopez-Torres, Cesar Elosua, Miguel Hernaez, Javier Goicoechea, Francisco J. Arregui
... In this paper a nanocoating that shows a superhydrophilic behavior (with a contact angle close to 0°) is transformed into a superhydrophobic nanofilm (whose contact angle is 165°) following a procedure that needs no nanoparticles to generate the nano-roughness required for superhydrophobicity. The superhydrophilic nanocoating was fabricated using poly (allylamine hydrochloride) (PAH) and poly (sodium phosphate) (PSP) combined by means of the Layer-by-Layer (LbL) technique. Seven different nanocoatings were constructed with different number of bilayers (4, 8, 12, 16, 20, 30 and 40) being the concentration of both polymers 10−3M. The analysis was conducted studying three different features: roughness, thickness and contact angle. The results show that initially, the contact angle of the nanofilms above 20 bilayers is close to 0°, that is, the minimum value for a superhydrophilic coating. These surfaces were functionalized using 1H,1H,2H,2H-Perfluorodecyltriethoxsilane to transform them into hydrophobic coatings by Chemical Vapor Disposition (CVD). Thereafter, the nanofilms showed a superhydrophobic behavior with a contact angle of 165° for the 40 bilayers films. The results of roughness and the images of AFM prove that the morphology of the nanocoating is preserved.