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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Circular orientation fluorescence emitter imaging (COFEI) of rotational motion of motor proteins

Single-molecule fluorescence polarization technique has been utilized to detect structural changes in biomolecules and intermolecular interactions. Here we developed a single-molecule fluorescence polarization measurement system, named circular orientation fluorescence emitter imaging (COFEI), in which a ring pattern of an acquired fluorescent image (COFEI image) represents an orientation of a polarization and a polarization factor. Rotation and pattern change of the COFEI image allow us to find changes in the polarization by eye and further values of the parameters of a polarization are determined by simple image analysis with high accuracy. We validated its potential applications of COFEI by three assays: 1) Detection of stepwise rotation of F{sub 1}-ATPase via single quantum nanorod attached to the rotary shaft γ; 2) Visualization of binding of fluorescent ATP analog to the catalytic subunit in F{sub 1}-ATPase; and 3) Association and dissociation of one head of dimeric kinesin-1 on the microtubule during its processive movement through single bifunctional fluorescent probes attached to the head. These results indicate that the COFEI provides us the advantages of the user-friendly measurement system and persuasive data presentations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Effects of Vanadium on Modification of Iron-Rich Intermetallics and Mechanical Properties in A356 Cast Alloys with 1.5 wt.% Fe

Formation of Fe-rich intermetallics and mechanical properties of vanadium-modified A356 cast alloys with 1.5 wt.% Fe were investigated using image analysis, scanning electron microscopy, differential scanning calorimetry, and a tensile test. The results showed that V content has no apparent influence on α-Al grain size in A356 alloys with high Fe content. Also, 0.8 wt.% V is beneficial for improving mechanical properties in A356 cast alloys with high Fe content. Specifically, these results can be attributed to the formation of Chinese script or block α-Fe phases, refined needle-like β-Fe (Al{sub 5}FeSi), and decreased porosities. An excessive amount of V deteriorates mechanical properties of alloys because it leads to VSi{sub 2} formation, large sized iron-rich intermetallics, and increased porosities.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Growth kinetics of Al–Fe intermetallic compounds during annealing treatment of friction stir lap welds

In this study, we explored the growth kinetics of the Al–Fe intermetallic (IM) layer at the joint interface of the St-12/Al-5083 friction stir lap welds during post-weld annealing treatment at 350, 400 and 450 °C for 30 to 180 min. Optical microscope (OM), field emission gun scanning electron microscope (FEG-SEM) and transmission electron microscope (TEM) were employed to investigate the structure of the weld zone. The thickness and composition of the IM layers were evaluated using image analysis system and electron back-scatter diffraction (EBSD), respectively. Moreover, kernel average misorientation (KAM) analysis was performed to evaluate the level of stored energy in the as-welded state. The results showed that the growth kinetics of the IM layer was not governed by a parabolic diffusion law. Presence of the IM compounds as well as high stored energy near the joint interface of the as-welded sample was recognized to be the origin of the observed deviation from the parabolic diffusion law. - Highlights: • This work provided a new insight into growth kinetics of Al–Fe IM thickness. • The growth kinetics of IM layer was not governed by a parabolic diffusion law. • IM near the joint interface was the origin of deviation from the parabolic law. • High stored energy at joint interface was origin of deviation from parabolic law.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity - sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing. In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.

36 MATERIALS SCIENCE↗
DOE OSTI2015

MO-F-CAMPUS-J-05: Using 2D Relative Gamma Analysis From EPID Image as a Predictor of Plan Deterioration Due to Anatomical Changes

Purpose: One of the side effects of radiotherapy for head and neck (H&N) cancer is the patient’s anatomical changes. The changes can strongly affect the planned dose distribution. In this work, our goal is to demonstrate that relative analysis of EPID images is a fast and simple method to detect anatomical changes that can have a strong dosimetric impact on the treatment plan for H&N patients. Methods: EPID images were recorded at every beam and all fractions for 50 H&N patients. Of these, five patients that showed important anatomical changes were selected to evaluate dosimetric impacts of these changes and to correlate them with a 2D relative gamma analysis of EPID images. The planning CT and original contours were deformed onto CBCTs (one mid treatment and one at the end of treatment). By using deformable image registration, it was possible to map accurate CT numbers from the planning CT to the anatomy of the day obtained with CBCTs. Clinical treatment plan were then copied on the deformed dataset and dose was re-computed. In parallel, EPID images were analysed using the gamma index (3%3mm) relative to the first image. Results: It was possible to divide patients in two distinct, statistically different (p<0.001) categories using an average gamma index of 0.5 as a threshold. Below this threshold no significant dosimetric degradation of the plan are observed. Above this threshold two types of plan deterioration were seen: (1) target dose increases, but coverage remains adequate while dose to at least one OAR increases beyond tolerances; (2) the OAR doses remain low, but the target dose is reduced and coverage becomes inadequate. Conclusion: Relative analysis gamma of EPID images could indeed be a fast and simple method to detect anatomical changes that can potentially deteriorates treatment plan for H&N patients. This work was supported in part by Varian Medical System.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

High-Resolution Electron Microscopy and Kinetic Studies of Precipitation Hardening Reactions in Cast Al-5.8Zn-2.2Mg-2.5Cu

Precipitation age hardening (T6) response of Al-5.8Zn-2.2Mg-2.5Cu alloy in near-net-shaped cast condition was investigated. Cast samples were manufactured using the controlled diffusion solidification (CDS) technology combined with a metallic mold tilt pour gravity casting process. This study was conducted using (1) non-isothermal aging during differential scanning calorimetry (DSC) experiments and (2) isothermal aging during which transient bulk and micro-hardness measurements taken at four aging temperatures of 343, 393, 433 and 473 K. A detailed microstructural investigation combined with a quantitative image analysis was carried out on both DSC and hardness specimens using high-resolution electron microscopy (HREM) and energy-dispersive spectroscopy (EDS) elemental mappings. Hardness measurements were analyzed using a kinetic modeling approach (single state variable combined with a kinetic equation that is valid for the Al-Zn-Mg-Cu alloys). The results confirm the formation of hardening phases of GP zone, intermediate hardening metastable phase η′ and equilibrium phase η. The results of calorimetric measurements, electron microscopy and selected area diffraction patterns are in good agreement and confirm transient precipitation/dissolution sequences. A mean value of activation energy Q{sub A} of 75 kJ/mol was evaluated for combined bulk diffusion rate of alloying elements during precipitation of strengthening phases within Al matrix.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Controlling melt flow by nanoparticles to eliminate surface wave induced surface fluctuation

The high surface roughness is one of the major challenges encountered in laser metal additive manufacturing (AM) processes, which is closely related to the melt flow behavior. However, how to control the melt flow in laser metal AM processes to improve surface finish is unknown. Here we reveal the effects of nanoparticles on melt flow behavior at every location of melt pool during laser metal AM process for the first time using Al6061 + TiC nanoparticles system and achieve significant improvement of surface finish by using TiC nanoparticles to control the melt flow and damp the surface wave. Based on the in-situ x-ray imaging observation, the surface wave is fully damped after adding TiC nanoparticles, compared with only 56% damping without nanoparticles during LPBF of Al6061. Our in-depth in-situ x-ray imaging analysis and viscosity measurement enable us to identify that nanoparticle-induced increase of viscosity causes the fully damping of the surface wave by (1) increasing the internal fluid friction for more efficient wave amplitude reduction, (2) controlling the melt flow to increase the surface wave number, (3) controlling the melt flow to increase the wave damping time. Furthermore, we also quantified the relative contributions of increasing fluid friction, increasing wave number, and increasing damping time to wave damping, which account for 61%, 25%, and 14%, respectively. Furthermore, our research provides the mechanisms and potential method to address the surface finish challenge in laser metal AM processes.

36 MATERIALS SCIENCE↗
DOE OSTI2014

WE-A-17A-09: Exploiting Electromagnetic Technologies for Real-Time Seed Drop Position Validation in Permanent Implant Brachytherapy

Purpose: To report on preliminary results validating the performance of a specially designed LDR brachytherapy needle prototype possessing both electromagnetic (EM) tracking and seed drop detection abilities. Methods: An EM hollow needle prototype has been designed and constructed in collaboration with research partner Philips Healthcare. The needle possesses conventional 3D tracking capabilities, along with a novel seed drop detection mechanism exploiting local changes of electromagnetic properties generated by the passage of seeds in the needle's embedded sensor coils. These two capabilities are exploited by proprietary engineering and signal processing techniques to generate seed drop position estimates in real-time treatment delivery. The electromagnetic tracking system (EMTS) used for the experiment is the NDI Aurora Planar Field Generator. The experiment consisted of dropping a total of 35 seeds in a prismatic agarose phantom, and comparing the 3D seed drop positions of the EMTS to those obtained by an image analysis of subsequent micro-CT scans. Drop position error computations and statistical analysis were performed after a 3D registration of the two seed distributions. Results: Of the 35 seeds dropped in the phantom, 32 were properly detected by the needle prototype. Absolute drop position errors among the detected seeds ranged from 0.5 to 4.8 mm with mean and standard deviation values of 1.6 and 0.9 mm, respectively. Error measurements also include undesirable and uncontrollable effects such as seed motion upon deposition. The true accuracy performance of the needle prototype is therefore underestimated. Conclusion: This preliminary study demonstrates the potential benefits of EM technologies in detecting the passage of seeds in a hollow needle as a means of generating drop position estimates in real-time treatment delivery. Such tools could therefore represent a potentially interesting addition to existing brachytherapy protocols for rapid dosimetry validation. Equipments and fundings for this project were provided by Philips Medical.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS1989

Mass balance investigation of alpine glaciers through LANDSAT TM data

An analysis of LANDSAT Thematic Mapper (TM) data of the Pasterze Glacier and the Kleines Fleisskees in the Austrian Alps was undertaken and compared with meteorological data of nearby weather stations. Alpine or valley glaciers can be used to study regional and worldwide climate changes. Alpine glaciers respond relatively fast to a warming or cooling trend in temperature through an advance or a retreat of the terminus. In addition, the mass balance of the glacier is being affected. Last year two TM scenes of the Pasterze Glacier of Aug. 1984 and Aug. 1986 were used to study the difference in reflectance. This year, in addition to the scenes from last year, one MSS scene of Aug. 1976 and a TM scene from 1988 were examined for both the Pasterze Glacier and the Kleines Fleisskees. During the overpass of the LANDSAT on 6 Aug. 1988 ground truthing on the Pasterze Glacier was undertaken. The results indicate that there was considerable more reflectance in 1976 and 1984 than in 1986 and 1988. The climatological data of the weather stations Sonnblick and Rudolfshuette were examined and compared with the results found through the LANDSAT data. There were relations between the meteorological and LANDSAT data: the average temperature over the last 100 years showed an increase of .4 C, the snowfall was declining during the same time period but the overall precipitation did not reveal any significant change over the same period. With the use of an interactive image analysis computer, the LANDSAT scenes were studied. The terminus of the Pasterze Glacier retreated 348 m and the terminus of the Kleines Fleisskees 121 m since 1965. This approach using LANDSAT MSS and TM digital data in conjunction with meteorological data can be effectively used to monitor regional and worldwide climate changes.

Bayr, Klaus J.↗
DOE OSTI2014

Neutron radiography and X-ray computed tomography for quantifying weathering and water uptake processes inside porous limestone used as building material

Euville and Savonnières limestones were weathered by acid test and this resulted in the formation of a gypsum crust. In order to characterize the crystallization pattern and the evolution of the pore structure below the crust, a combination of high resolution X-ray computed tomography and SEM–EDS was used. A time lapse sequence of the changing pore structure in both stones was obtained and afterwards quantified by using image analysis. The difference in weathering of both stones by the same process could be explained by the underlying microstructure and texture. Because water and moisture play a crucial role in the weathering processes, water uptake in weathered and non-weathered samples was characterized based on neutron radiography. In this way the water uptake was both visualized and quantified in function of the height of the sample and in function of time. In general, the formation of a gypsum crust on limestone slows down the initial water uptake in the materials. - Highlights: • Time lapse sequence in 3D of changing pore structures inside limestone • A combination of X-ray CT, SEM and neutron radiography was used. • Quantification of water content in function of time, height and weathering • Characterization of weathering processes due to gypsum crystallization.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Low Phosphorylated AKT Expression in Laryngeal Cancer: Indications for a Higher Metastatic Risk

Purpose: To validate the association of phosphorylated (p)AKT with lymph node metastasis in an independent, homogeneous cohort of patients with larynx cancer. Methods and Materials: Seventy-eight patients with laryngeal cancer were included. Epidermal growth factor receptor, pAKT, vimentin, E-cadherin, hypoxia, and blood vessels were visualized in biopsy material using immunohistochemistry. Positive tumor areas and spatial relationships between markers were assessed by automated image analysis. In 6 laryngeal cancer cell lines, E-cadherin and vimentin messenger RNA was quantified by real-time polymerase chain reaction and by immunohistochemistry before and after treatment with the pAKT inhibitor MK-2206. Results: A significant correlation was found between low pAKT in the primary tumor and positive lymph node status (P=.0005). Tumors with lymph node metastases had an approximately 10-fold lower median pAKT value compared with tumors without lymph node metastases, albeit with large intertumor variations, validating our previous results. After inhibition of pAKT in laryngeal cancer cells with MK-2206, up-regulation of vimentin and a downregulation of E-cadherin occurred, consistent with epithelial–mesenchymal transition. Conclusion: Low pAKT expression in larynx tumors is associated with lymph node metastases. Further, inhibition of pAKT in laryngeal cancer induces epithelial–mesenchymal transition, predisposing for an increased metastatic risk.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Diffraction data from aerosolized Coliphage PR772 virus particles imaged with the Linac Coherent Light Source

Single Particle Imaging (SPI) with intense coherent X-ray pulses from X-ray free-electron lasers (XFELs) has the potential to produce molecular structures without the need for crystallization or freezing. Here we present a dataset of 285,944 diffraction patterns from aerosolized Coliphage PR772 virus particles injected into the femtosecond X-ray pulses of the Linac Coherent Light Source (LCLS). Additional exposures with background information are also deposited. The diffraction data were collected at the Atomic, Molecular and Optical Science Instrument (AMO) of the LCLS in 4 experimental beam times during a period of four years. The photon energy was either 1.2 or 1.7 keV and the pulse energy was between 2 and 4 mJ in a focal spot of about 1.3 μm x 1.7 μm full width at half maximum (FWHM). The X-ray laser pulses captured the particles in random orientations. The data offer insight into aerosolised virus particles in the gas phase, contain information relevant to improving experimental parameters, and provide a basis for developing algorithms for image analysis and reconstruction.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Wnt interaction and extracellular release of prominin-1/CD133 in human malignant melanoma cells

Prominin-1 (CD133) is the first identified gene of a novel class of pentaspan membrane glycoproteins. It is expressed by various epithelial and non-epithelial cells, and notably by stem and cancer stem cells. In non-cancerous cells such as neuro-epithelial and hematopoietic stem cells, prominin-1 is selectively concentrated in plasma membrane protrusions, and released into the extracellular milieu in association with small vesicles. Previously, we demonstrated that prominin-1 contributes to melanoma cells pro-metastatic properties and suggested that it may constitute a molecular target to prevent prominin-1-expressing melanomas from colonizing and growing in lymph nodes and distant organs. Here, we report that three distinct pools of prominin-1 co-exist in cultures of human FEMX-I metastatic melanoma. Morphologically, in addition to the plasma membrane localization, prominin-1 is found within the intracellular compartments, (e.g., Golgi apparatus) and in association with extracellular membrane vesicles. The latter prominin-1–positive structures appeared in three sizes (small, ≤40 nm; intermediates ∼40–80 nm, and large, >80 nm). Functionally, the down-regulation of prominin-1 in FEMX-I cells resulted in a significant reduction of number of lipid droplets as observed by coherent anti-Stokes Raman scattering image analysis and Oil red O staining, and surprisingly in a decrease in the nuclear localization of beta-catenin, a surrogate marker of Wnt activation. Moreover, the T-cell factor/lymphoid enhancer factor (TCF/LEF) promoter activity was 2 to 4 times higher in parental than in prominin-1-knockdown cells. Collectively, our results point to Wnt signaling and/or release of prominin-1–containing membrane vesicles as mediators of the pro-metastatic activity of prominin-1 in FEMX-I melanoma. - Highlights: ► First report of release of prominin-1–containing microvesicles from cancer cells. ► Pro-metastatic role of prominin-1–containing microvesicles in FEMX-I melanoma. ► Down-regulation of prominin-1 results in decreased nuclear localization of β-catenin. ► Wnt signaling as mediator of the pro-metastatic activity of prominin-1.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

A measurement technique to determine the calibration accuracy of an electromagnetic tracking system to radiation isocenter

Purpose: To present and characterize a measurement technique to quantify the calibration accuracy of an electromagnetic tracking system to radiation isocenter.Methods: This technique was developed as a quality assurance method for electromagnetic tracking systems used in a multi-institutional clinical hypofractionated prostate study. In this technique, the electromagnetic tracking system is calibrated to isocenter with the manufacturers recommended technique, using laser-based alignment. A test patient is created with a transponder at isocenter whose position is measured electromagnetically. Four portal images of the transponder are taken with collimator rotations of 45° 135°, 225°, and 315°, at each of four gantry angles (0°, 90°, 180°, 270°) using a 3 × 6 cm{sup 2} radiation field. In each image, the center of the copper-wrapped iron core of the transponder is determined. All measurements are made relative to this transponder position to remove gantry and imager sag effects. For each of the 16 images, the 50% collimation edges are identified and used to find a ray representing the rotational axis of each collimation edge. The 16 collimator rotation rays from four gantry angles pass through and bound the radiation isocenter volume. The center of the bounded region, relative to the transponder, is calculated and then transformed to tracking system coordinates using the transponder position, allowing the tracking system's calibration offset from radiation isocenter to be found. All image analysis and calculations are automated with inhouse software for user-independent accuracy. Three different tracking systems at two different sites were evaluated for this study.Results: The magnitude of the calibration offset was always less than the manufacturer's stated accuracy of 0.2 cm using their standard clinical calibration procedure, and ranged from 0.014 to 0.175 cm. On three systems in clinical use, the magnitude of the offset was found to be 0.053 ± 0.036, 0.121 ± 0.023, and 0.093 ± 0.013 cm.Conclusions: The method presented here provides an independent technique to verify the calibration of an electromagnetic tracking system to radiation isocenter. The calibration accuracy of the system was better than the 0.2 cm accuracy stated by the manufacturer. However, it should not be assumed to be zero, especially for stereotactic radiation therapy treatments where planning target volume margins are very small.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

TH-A-19A-01: An Open Source Software for Proton Treatment Planning in Heterogeneous Medium

Purpose: Due to its success in Radiation Oncology during the last decade, interest in proton therapy is on the rise. Unfortunately, despite the global enthusiasm in the field, there is presently no free, multiplatform and customizable Treatment Planning System (TPS) providing proton dose distributions in heterogenous medium. This restricts substantially the progress of clinical research for groups without access to a commercial Proton TPS. The latest implementation of our pencil beam dose calculation algorithm for proton beams within the 3D Slicer open-source environment fulfills all the conditions described above. Methods: The core dose calculation algorithm is based on the Hong algorithm (1), which was upgraded with the Kanematsu theory describing the evolution of the lateral scattering of proton beamlets in heterogeneous medium. This algorithm deals with both mono-energetic beams and Spread Out Bragg Peak (SOBP). In order to be user-friendly, we provide a graphical user interface implemented with the Qt libraries, and visualization with the 3D Slicer medical image analysis software. Two different pencil beam algorithms were developed, and the clinical proton beam line at our facility was modeled. Results: The dose distributions provided by our algorithms were compared to dose distributions coming from both commercialized XiO TPS and literature (dose measurements, GEANT4 and MCNPx) and turned out to be in a good agreement, with maximum dose discrepancies of 5% in homogeneous phantoms and 10% in heterogeneous phantoms. The algorithm of SOBP creation from an optimized weigthing of mono-energetic beams results in flat SOBP. Conclusion: We hope that our efforts in implementing this new, open-source proton TPS will help the research groups to have a free access to a useful, reliable proton dose calculation software.(1) L. Hong et al., A pencil beam algorithm for proton dose calculations, Phys. Med. Biol. 41 (1996) 1305–1330. This project is paid for by NCI/MGH Federal share as a research grant.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Early Embolization After Carotid Artery Stenting with Mesh-Covered Stent: Role of Diffusion-Weighted Magnetic Resonance Imaging as Pre-procedural Predictor and Discriminant Between Intra- and Post-procedural Events

Objectives: To evaluate the incidence and the time of onset of early micro-embolism after CAS (carotid artery stenting) with two different mesh-covered stents and to assess the role of DW-MRI (Diffusion-weighted magnetic resonance imaging) in their prediction. Methods: Single-institution prospective study including 50 patients (33 male, median age 74 years) who underwent CAS with Roadsaver{sup ®} or CGuard™. All patients with primary stenosis (37/50, 74%) had carotid plaque DW-MRI pre-procedure, with both qualitative evaluation of the hyperintensity and ADC (apparent diffusion coefficient) measurement of the plaque. All patients had brain DW-MRI pre-procedure, at 1 h, 24 h and 30 days post-procedure to evaluate the appearance of hyperintense lesions over time. Imaging analysis was performed in a double-blinded fashion by two radiologists. Results: There were no statistically significant differences between the two stents both in the incidence at 1 h (P = 0.23) and 24 h (P = 0.36) and in the volume of new DWI hyperintense brain lesions at 24 h (P = 0.27). Thirty-four new asymptomatic lesions in 19 patients (38%) were reported: 4 (11.8%) at 1 h, 30 (88.2%) at 24 h. The 30-day DWI-MR showed complete resolution of all lesions and no evidence of new lesion. The incidence of new lesions at 24 h resulted significantly higher in patients with DWI hyperintense carotid plaques (12/16, 75% vs. 0/21, 0%, P < 0.0001). This result was paralleled by the difference in ADC value (0.83 ± 0.21 vs. 1.42 ± 0.52). Conclusion: The majority of early asymptomatic brain lesion occurred during the first 24 h after CAS. Pre-procedure high DWI signal of the plaque was associated with an increased incidence of post-procedure microembolizations.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Enabling reactive microscopy with MicroMator

Microscopy image analysis has recently made enormous progress both in terms of accuracy and speed thanks to machine learning methods and improved computational resources. This greatly facilitates the online adaptation of microscopy experimental plans using real-time information of the observed systems and their environments. Applications in which reactiveness is needed are multifarious. Here we report MicroMator, an open and flexible software for defining and driving reactive microscopy experiments. It provides a Python software environment and an extensible set of modules that greatly facilitate the definition of events with triggers and effects interacting with the experiment. We provide a pedagogic example performing dynamic adaptation of fluorescence illumination on bacteria, and demonstrate MicroMator’s potential via two challenging case studies in yeast to single-cell control and single-cell recombination, both requiring real-time tracking and light targeting at the single-cell level.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

The Determination of the Spatial Distribution of Indigenous Lipid Biomarkers in an Immature Jurassic Sediment Using Time-of-Flight–Secondary Ion Mass Spectrometry

The ability to detect and map lipids, including potential lipid biomarkers, within a sedimentary matrix using mass spectrometry (MS) imaging may be critical to determine whether potential lipids detected in samples returned from Mars are indigenous to Mars or are contaminants. Here, we use gas chromatography–mass spectrometry (GC-MS) and time-of-flight–secondary ion mass spectrometry (ToF-SIMS) datasets collected from an organic-rich, thermally immature Jurassic geologic sample to constrain MS imaging analysis of indigenous lipid biomarkers in geologic samples. GC-MS data show that the extractable fractions are dominated by C 27 –C 30 steranes and sterenes as well as isorenieratene derivatives. ToF-SIMS spectra from organic matter-rich laminae contain a strong, spatially restricted signal for ions m/z 370.3, m/z 372.3, and m/z 386.3, which we assign to C 27 sterenes, cholestane (C 27 ), and 4- or 24-methyl steranes (C 28 ), respectively, as well as characteristic fragment ions of isorenieratene derivatives, including m/z 133.1, m/z 171.1, and m/z 237.1. We observed individual steroid spatial heterogeneity at the scale of 10's to 100's of microns. The fine-scale heterogeneity observed implies that indigenous lipid biomarkers concentrated within specific regions may be detectable via ToF-SIMS in samples with even low amounts of organic carbon, including in samples returned from Mars.

59 BASIC BIOLOGICAL SCIENCES↗