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At least 1,765 records · Page 98

MO-FG-CAMPUS-IeP2-03: Validation of an SSDE-To-Organ-Dose Calculation Methodology Developed for Pediatric CT in An Adult Population

Purpose: To discover if a previously published methodology for estimating patient-specific organ dose in a pediatric population (5–55kg) is translatable to the adult sized patient population (> 55 kg). Methods: An adult male anthropomorphic phantom was scanned with metal oxide semiconductor field effect transistor (MOSFET) dosimeters placed at 23 organ locations in the chest and abdominopelvic regions to determine absolute organ dose. Organ-dose-to-SSDE correlation factors were developed by dividing individual phantom organ doses by SSDE of the phantom; where SSDE was calculated at the center of the scan volume of the chest and abdomen/pelvis separately. Organ dose correlation factors developed in phantom were multiplied by 28 chest and 22 abdominopelvic patient SSDE values to estimate organ dose. The median patient weight from the CT examinations was 68.9 kg (range 57–87 kg) and median age was 17 years (range 13–28 years). Calculated organ dose estimates were compared to published Monte Carlo simulated patient and phantom results. Results: Organ-dose-to-SSDE correlation was determined for a total of 23 organs in the chest and abdominopelvic regions. For organs fully covered by the scan volume, correlation in the chest (median 1.3; range 1.1–1.5) and abdominopelvic (median 0.9; range 0.7–1.0) was 1.0 ± 10%. For organs that extended beyond the scan volume (i.e. skin bone marrow and bone surface) correlation was determined to be a median of 0.3 (range 0.1–0.4). Calculated patient organ dose using patient SSDE agreed to better than 6% (chest) and 15% (abdominopelvic) to published values. Conclusion: This study demonstrated that our previous published methodology for calculating organ dose using patient-specific SSDE for the chest and abdominopelvic regions is translatable to adult sized patients for organs fully covered by the scan volume.

60 APPLIED LIFE SCIENCES↗

Accuracy of RGD approximation for computing light scattering properties of diffusing and motile bacteria

The study tests the accuracy of the Rayleigh-Gans-Debye (RGD) approximation against a rigorous scattering theory calculation for a simplified model of E. coli (about 1 micron in size) - a solid spheroid. A general procedure is formulated whereby the scattered field amplitude correlation function, for both polarized and depolarized contributions, can be computed for a collection of particles. An explicit formula is presented for the scattered intensity, both polarized and depolarized, for a collection of randomly diffusing or moving particles. Two specific cases for the intermediate scattering functions are considered: diffusing particles and freely moving particles with a Maxwellian speed distribution. The formalism is applied to microorganisms suspended in a liquid medium. Sensitivity studies revealed that for values of the relative index of refraction greater than 1.03, RGD could be in serious error in computing the intensity as well as correlation functions.

Kottarchyk, M.↗

A Comparative Study of Compressive Effects on the Morphology and Performance of Carbon Paper and Cloth Electrodes in Redox Flow Batteries

Compressing porous carbon electrodes is a common approach to improve flow battery performance, but the resulting impact on electrode structure, fluid dynamics, and cell performance is not well understood. Herein, microtomographic imaging, load cell testing, and flow cell diagnostics are employed to characterize how compression‐induced changes impact pressure drop, polarization, and mass‐transfer scaling. Five different compressions are tested, spanning ranges typically used in literature, for AvCarb 1071 cloth (0%, 9%, 20%, 25%, 32%) and Freudenberg H23 paper (0%, 8%, 12%, 17%, 22%). It is found that the two electrode structures have distinct responses to compression, resulting in differing optimal conditions identified for each material; specifically, the Freudenberg H23 exhibits lower combined ohmic, charge‐transfer, and mass‐transport values at 8% compression, resulting in improved electrochemical performance across all compressive values, as compared to the optimal AvCarb 1071 compression (20%). Overall, Freudenberg H23 exhibits a greater sensitivity to compression with peak electrochemical activity correlating with increased permeability, whereas AvCarb 1071 is insensitive to compressive loads but produces lower electrochemical performance. Herein, the trade‐offs of mechanical robustness on fluid‐dynamic and electrochemical performance between the two electrodes are demonstrated by the aforementioned findings, suggesting each could be used for specific operating environments.

25 ENERGY STORAGE↗

Development of an operando characterization stage for multi-modal synchrotron x-ray experiments

It is widely accepted that micro- and nanoscale inhomogeneities govern the performance of many thin-film solar cell absorbers. These inhomogeneities yield material properties (e.g., composition, structure, and charge collection) that are challenging to correlate across length scales and measurement modalities. The challenge is compounded if a correlation is sought during device operation or in conditions that mimic aging under particular stressors (e.g., heat and electrical bias). Correlative approaches, particularly those based on synchrotron x-ray sources, are powerful since they can access several material properties in different modes (e.g., fluorescence, diffraction, and absorption) with minimal sample preparation. Small-scale laboratory x-ray instruments have begun to offer multi-modality but are typically limited by low x-ray photon flux, low spatial resolution, or specific sample sizes. To overcome these limitations, a characterization stage was developed to enable multi-scale, multi-modal operando measurements of industrially relevant photovoltaic devices. The stage offers compatibility across synchrotron x-ray facilities, enabling correlation between nanoscale x-ray fluorescence microscopy, microscale x-ray diffraction microscopy, and x-ray beam induced current microscopy, among others. Furthermore, the stage can accommodate device sizes up to 25 × 25 mm 2 , offering access to multiple regions of interest and increasing the statistical significance of correlated properties. The stage materials can sustain humid and non-oxidizing atmospheres, and temperature ranges encountered by photovoltaic devices in operational environments (e.g., from 25 to 100 °C). As a case study, we discuss the functionality of the stage by studying Se-alloyed CdTe photovoltaic devices aged in the stage between 25 and 100 °C.

14 SOLAR ENERGY↗

Dynamical origins of weakly coupled relaxor behavior in Sn-doped (Ba,Ca)TiO 3 -BiScO 3

The peculiar characteristics of relaxors, viz., a frequency-dependent dielectric permittivity peak and good functional properties (dielectric, electromechanical, electrocaloric, etc.), are attributed to nanoscale regions with correlated dipoles, or polar nanoregions (PNRs). However, the exact nature of PNRs and their contribution to relaxor behavior remains debatable. In recent years, solid solutions of BaTiO3-BiMeO3 (where Me is a metal), have emerged as an interesting system with characteristics in between that of relaxors and dipole glasses. Here, we have examined the atomistic origins of weakly coupled relaxor behavior, specifically with regard to formation of PNRs, in Sn-doped (1-x)(Ba,Ca)TiO 3-x BiScO 3 using macroscopic polarization and neutron dynamic pair distribution function measurements. We show that the short-range atomic correlations observed within the PNRs dynamically fluctuate with frequencies of the order of THz. Furthermore the composition-dependent dielectric and polarization behaviors are critically influenced by the relative stability of the atomic correlations near ~1 THz, while the instantaneous atomic correlations are largely independent of x. The current results are discussed based on a model of intrinsic local modes distributed in a dielectrically soft matrix.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Methodologies for Verification and Validation of Space Launch System (SLS) Structural Dynamic Models

Responses to challenges associated with verification and validation (V&V) of Space Launch System (SLS) structural dynamics models are presented in this paper. Four methodologies addressing specific requirements for V&V are discussed. (1) Residual Mode Augmentation (RMA), which has gained acceptance by various principals in the NASA community, defines efficient and accurate FEM modal sensitivity models that are useful in test-analysis correlation and reconciliation and parametric uncertainty studies. (2) Modified Guyan Reduction (MGR) and Harmonic Reduction (HR, introduced in 1976), developed to remedy difficulties encountered with the widely used Classical Guyan Reduction (CGR) method, are presented. MGR and HR are particularly relevant for estimation of "body dominant" target modes of shell-type SLS assemblies that have numerous "body", "breathing" and local component constituents. Realities associated with configuration features and "imperfections" cause "body" and "breathing" mode characteristics to mix resulting in a lack of clarity in the understanding and correlation of FEM- and test-derived modal data. (3) Mode Consolidation (MC) is a newly introduced procedure designed to effectively "de-feature" FEM and experimental modes of detailed structural shell assemblies for unambiguous estimation of "body" dominant target modes. Finally, (4) Experimental Mode Verification (EMV) is a procedure that addresses ambiguities associated with experimental modal analysis of complex structural systems. Specifically, EMV directly separates well-defined modal data from spurious and poorly excited modal data employing newly introduced graphical and coherence metrics.

Coppolino, Robert N.↗

Digital Image Correlation of Concrete Slab at University of Tennessee, Knoxville

Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Some degradation mechanisms of concrete manifest themselves via swelling or by other shape deformation of the concrete. Specifically, degradation of concrete structure damaged by ASR is viewed as one of the dominant factors impacting the structural integrity of aging nuclear power plants. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. Number of nondestructive examination techniques (i.e., thermography, digital image correlation, mechanical deformation measurements, nonlinear impact resonance (DIC) acoustic spectroscopy, and vibro-acoustic modulation) is used to detect the damage caused by ASR. DIC techniques have been increasing in popularity, especially in micro- and nano-scale mechanical testing applications due to its relative ease of implementation and use. Advances in computer technology and digital cameras help this method moving forward. To ensure the best outcome of the DIC system, important factors in the experiment are identified. They include standoff distance, speckle size, speckle pattern, and durable paint. These optimal experimental options are selected basing on a thorough investigation. The resulting DIC deformation map indicates that this technique can be used to generate data related to degradation assessment of concrete structure damaged by the impact of ASR.

36 MATERIALS SCIENCE↗

Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D {sup 1}H/{sup 13}C/{sup 1}H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t{sub 1} and t{sub 3} periods, respectively. In addition to through-space and through-bond {sup 13}C/{sup 1}H and {sup 13}C/{sup 13}C chemical shift correlations, the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment also provides a COSY-type {sup 1}H/{sup 1}H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ({sup 1}H/{sup 1}H chemical shift correlation spectrum) at different {sup 13}C chemical shift frequencies from the 3D {sup 1}H/{sup 13}C/{sup 1}H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment would be useful to study the structure and dynamics of a variety of chemical and biological solids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Assessment of Myocarditis: Cardiac MR, PET/CT, or PET/MR?

Purpose of Review: Diagnosis of myocarditis is challenging given its variable clinical manifestations and non-specific laboratory findings. Cardiac magnetic resonance (MR) is currently the preferred imaging modality for the diagnosis of myocarditis. {sup 18}F-fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT), as a functional imaging tool, has a potential role in the assessment of myocarditis by detecting the underlying myocardial inflammatory activity. Data are accumulating that simultaneous cardiac PET/MR may have complementary and incremental values for the evaluation of myocarditis compared to PET/CT or cardiac MR alone. The article aims to summarize the findings in the literature and discuss future directions of cardiac PET/MR for myocarditis. Recent Findings: The Lake Louis Criteria (CLL) of cardiac MR is widely used for the diagnosis of myocarditis. It has an overall acceptable sensitivity of 67% and specificity of 91% for acute myocarditis but does not have the same accuracy for chronic myocarditis. FDG PET/CT is capable of assessing myocarditis by providing metabolic information of inflammation as increased myocardial FDG uptake. In addition to reduced radiation exposure, FDG PET performed on a hybrid PET/MR may detect more myocarditis than FDG PET/CT, because of the delayed PET acquisition time on PET/MR. Case-based observations and small clinical studies of FDG PET/MR have shown that FDG PET findings as abnormally increased myocardial uptake correlate well with the cardiac MR biomarkers. FDG PET findings may add complementary and incremental values to cardiac MR by improving the sensitivity of cardiac MR for mild or borderline myocarditis, and increasing specificity for chronic myocarditis. Summary: Preliminary data from retrospective and case-based observational studies have suggested the complementary and incremental values of simultaneous cardiac FDG PET/MR for evaluation of myocarditis, compared to PET/CT or MR alone. Well-designed studies are needed to confirm the findings and to assess the value of cardiac PET/MR for clinical management and more importantly patient’s outcome in both acute and chronic myocarditis.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Classical signatures of quenched and thermal disorder in the dynamics of correlated spin systems

Neutron scattering is frequently used to look for evidence of features indicative of quantum-entangled phases of matter such as continua from fractionalisation or quantised excitations. However, the non-specificity of these features and difficulty of both fully quantum treatments and semiclassical models of disorder, make the diagnosis of such states problematic. Here, we demonstrate the feasibility of semiclassical treatments of disordered systems for supercells of ~10 000 spins. By examining a number of classically disordered models we show the presence of quantised excitations, broad continua and anomalous damping originating from quenched disorder or large classical degeneracies.

36 MATERIALS SCIENCE↗

Correlation with flight of some aeroelastic model studies in the NASA Langley transonic dynamics tunnel

The NASA Langley transonic dynamics tunnel, which has a variable density Freon-12 (or air) test medium, was designed specifically for the study of dynamics and aeroelastic problems of aerospace vehicles. During the 15 years of operation of this facility, there have been various opportunities to compare wind tunnel and flight test results. Some of these opportunities arise from routine flight checks of the prototypes; others, from carefully designed comparative wind-tunnel and flight experiments. Such data obtained from various published and unpublished sources are presented. The topics covered are: gust and buffet response, control surface effectiveness, flutter, and active control of aeroelastic effects. Some benefits and shortcomings of Freon-12 as a test medium are also discussed. Although areas of uncertainty are evident and there is a continuing need for improvements in model simulation and testing techniques, the results presented indicate that predictions from aeroelastic model tests are, in general, substantiated by full scale flight tests.

Reed, W. H., III↗

microRNA-9 selectively targets LMX1A to promote gastric cancer cell progression

Highlights: • miR-9 overexpression downregulates LMX1A, promoting gastric cancer (GC) cell proliferation. • miR-9 inhibition upregulates LMX1A to induce GC cell apoptosis. • LMX1A is the direct and primary target of miR-9 in GC cells. • miR-9 upregulation in human GC tissues correlates with LMX1A downregulation. LIM homeobox transcription factor 1, alpha (LMX1A) is downregulated in human gastric cancer (GC), functioning as a tumor suppressor. The current study aims to identify specific microRNA that can regulate LMX1A expression. By sequence analysis of LMX1A mRNA 3′-untranslated region (3′-UTR), we show that microRNA-9 (miR-9) putatively targets human LMX1A. In established (AGS cells) and primary human GC cells, ectopic overexpression of miR-9 by a lentiviral construct decreased LMX1A 3′-UTR activity, causing LMX1A mRNA and protein downregulation. Functional analyses show that miR-9 overexpression enhanced GC cell survival and proliferation. On the contrary, miR-9 inhibition by antagomir-9 lentivirus increased LMX1A 3′-UTR activity to upregulate LMX1A mRNA and protein expression, causing GC cell apoptosis. CRISPR/Cas9-mediated LMX1A knockout promoted AGS cell survival and proliferation. Importantly, miR-9 and antagomiR-9 were ineffective to the function of LMX1A-knockout AGS cells. In human GC tissues miR-9 is upregulated, which is negatively correlated with LMX1A downregulation. Together, we conclude that miR-9 selectively targets LMX1A to promote GC cell progression.

60 APPLIED LIFE SCIENCES↗

TU-AB-303-05: Clinical Guidelines for Determining When An Adaptive Replan May Be Warranted for Head and Neck Patients

Purpose: Tools are now available to perform daily dose assessment in radiotherapy, however, guidance is lacking as to when to replan to limit increase in normal tissue dose. This work performs statistical analysis to provide guidance for when adaptive replanning may be necessary for head/neck (HN) patients. Methods: Planning CT and daily kVCBCT images for 50 HN patients treated with VMAT were retrospectively evaluated. Twelve of 50 patients were replanned due to anatomical changes noted over their RT course. Daily dose assessment was performed to calculate the variation between the planned and delivered dose for the 38 patients not replanned and the patients replanned using their delivered plan. In addition, for the replanned patients, the dose that would have been delivered if the plan was not modified was also quantified. Deviations in dose were analyzed before and after replanning, the daily variations in patients who were not replanned assessed, and the predictive power of the deviation after 1, 5, and 15 fractions determined. Results: Dose deviations were significantly reduced following replanning, compared to if the original plan would have been delivered for the entire course. Early deviations were significantly correlated with total deviations (p<0.01). Using the criteria that a 10% increase in the final delivered dose indicates a replan may be needed earlier in the treatment course, the following guidelines can be made with a 90% specificity after the first 5 fractions: deviations of 7% in the mean dose to the inferior constrictors and 5% in the mean dose to the parotid glands and submandibular glands. No significant dose deviations were observed in any patients for the CTV -70Gy (max deviation 4%). Conclusions: A 5–7% increase in mean dose to normal tissues within the first 5 fractions strongly correlate to an overall deviatios in the delivered dose for HN patients. This work is funded in part by NIH 2P01CA059827-16.

60 APPLIED LIFE SCIENCES↗

A statistical approach to analyzing domain dynamics in ferroelectric crystals using X-ray photon correlation spectroscopy

Ferroelectric materials exhibit strong electromechanical coupling, largely influenced by their domain structures. Numerous microstructural studies indicate that smaller domains with higher domain wall density generally enhance domain wall motion, although some inconsistencies have been reported. In this work, we use X-ray photon correlation spectroscopy (XPCS) to probe dynamic response in Pb(Mg 1/3 Nb 2/3 )O 3 -29PbTiO 3 (PMN-29PT) single crystals under applied electric fields. We introduce a two-field correlation approach, adapted from conventional two-time correlation to quantify dynamics. Statistical analysis reveals that both [001]-oriented direct current (DC) and alternating current (AC) poled samples show Poisson-like behavior within specific electric field regions. The DC-poled samples exhibit more frequent domain wall jump events but with smaller amount of decorrelation per jump event, whereas the AC-poled samples show fewer jump events with larger decorrelation per jump event. This observation aligns with the prevalence of 109° domain walls in the AC-poled samples, which contribute to more domain wall motion. These findings provide experimental evidence of collective domain wall motion and establish a direct connection between mesoscale dynamics and electromechanical response.

36 MATERIALS SCIENCE↗

A Chaos Theoretic Approach to Animal Activity Recognition

Animal activity is a descriptor that can be potentially used to track the health and well-being, which is obviously very important to improve the management process and productivity of farms. This paper deals with an animal behavior recognition problem using a chaos theory approach where we adopt such a technique for automatic classification of calves behavioral states. Two main mutually exclusive behaviors are of interest, namely, lying and standing/walking with six possible activities: feeding, drinking water, drinking milk, playing, rumination, and neutral. The time series generated by ear-tags with a 3D-accelerometer after a wavelet denoising transformation and frequency stabilization are treated as representations of the nonlinear dynamical system. The dynamical system of a certain animal state exhibits specific strange attractor in a phase space. A characterization of such an attractor is performed through metric, dynamic, and topological invariants including Lyapunov exponent, correlation dimension, length of a phase trajectory, sum of edges forming a convex hull and others. These measures are used as a feature vector for the subsequent classification. In a cross validation scheme, six classifiers are built on each training set, and the hyper-parameters are optimized using an inner validation set. The classifier that reaches the highest accuracy on the inner validation set is used to classify the outer validation set. It is shown that this approach can be useful at predicting activity states as an alternative methodology for the animal behavior state recognition problem with acceptable classification accuracy. Furthermore it is possible to include this procedure as part of an ensemble method in machine learning where a combination of different models is used.

97 MATHEMATICS AND COMPUTING↗

Influence of geometry on columnar to equiaxed transition during electron beam powder bed fusion of IN718

Correlation between spot-melt scan parameters (linear spot-density aka areal energy density), build geometry, and solidification microstructure evolution (columnar vs equiaxed) in a powder bed fusion technology is investigated. It is shown that to maintain the equiaxed solidification microstructure evolution in electron beam powder bed additive manufacturing (AM), the areal energy density per layer needs to be scaled with respect to the 2D cross-sectional area of the layer being melted. Samples with two different cross-sectional areas (40 × 40 mm and 20 × 20 mm) have been fabricated with varying areal energy densities. For a given square cross-section (20 × 20 mm), increasing the areal energy density (4.8 MJ/sq.m to 14.7 MJ/sq.m) transitioned the solidification microstructure from columnar to equiaxed. The observed microstructure data (Electron Back Scattered Diffraction - EBSD) is quantified by calculating the principal component (PC) score using a spatial statistics methodology. The sample with equiaxed grains is found to have a low PC score while the sample with columnar grain had a high PC score. A semi-analytical model is used to simulate the heat transfer and the local solidification conditions as a function of processing parameters (linear spot-density). The result from the heat transfer model is correlated with previously quantified microstructure data. Space-Time analysis of the melt pattern is done and correlated with the observed microstructure. In addition, from the findings, appropriate parameters have been used to additively manufacture a turbine blade with site-specific or hybrid solidification microstructure (traditional fabrication possible via a patented method of localized cold working and heat treatment).

36 MATERIALS SCIENCE↗

Aberrantly expressed lncRNAs identified by microarray analysis in CD4+T cells in asthmatic patients

Highlights: • Long noncoding RNAs may be potential biomarkers to diagnose asthma. • Long noncoding RNAs may regulate the expression of cytokines in CD4+T cells in asthma. • Specific long noncoding RNAs are related with the characteristics of asthmatic patients. The aim of the study was to determine the expression profiles of message RNAs and long non-coding RNAs in CD4{sup +}T cells of asthmatic patients and to explore the clinical value and biological function. Expression profiles in CD4{sup +}T cells of asthmatic patients and healthy controls were analyzed by microarray. We found 2725 lncRNAs and 3167 mRNAs differentially expressed. The data were validated by quantitative real time polymerase chain reaction, with 3 up-regulated (ENST00000444682, ENST00000566098, ENST00000583179) and 1 down-regulated (ENST00000579468) lncRNAs found. Receiver operating characteristic curve analysis showed the area under the curve was 0.7058, 0.9026, 0.8361, 0.8316, respectively. Spearman correlation analysis showed that ENST00000566098 was positively related with IL-13 and ENST00000579468 was positively related with peak expiratory flow. Bioinformatics analyses were performed to explore the function of lncRNAs. Specific lncRNAs aberrantly expressed in CD4{sup +}T cells may take part in the development of asthma and may be used as biomarkers for diagnosis.

60 APPLIED LIFE SCIENCES↗