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At least 649 records · Page 36

Robust surfactant-assisted one-pot sample preparation for label-free single-cell and nanoscale proteomics

With advanced mass spectrometry (MS)-based proteomics, genome-scale proteome coverage can be achieved from bulk cells. However, such bulk measurement obscures cell to cell heterogeneity, precluding proteome profiling of single cells and small numbers of cells of interest. To address this issue, in recent 5 years there are a surge of small sample preparation methods developed for robust effective collection and processing of single cells and small numbers of cells for in-depth MS-based proteome profiling. Based on their broad accessibility, they can be categorized into two types: specific device- and standard PCR tube- or multi-well plate-based methods. Herein we describe the detailed protocol of our recently developed, easily adoptable, Surfactant-assisted One-Pot (SOP) sample preparation coupled with MS method termed SOP-MS for label-free single-cell and nanoscale proteomics. SOP-MS capitalizes on the combination of a MS-compatible surfactant, DDM (n-Dodecyl-ß-D-maltoside), and standard low-bind PCR tube or multi-well plate for ‘all-in-one’ one-pot sample preparation without sample transfer. With its robust and convenient features, SOP-MS can be readily implemented in any MS laboratory for single-cell and nanoscale proteomics. With further improvements in MS detection sensitivity and sample throughput, we believe that SOP-MS could open an avenue for single-cell proteomics with broad applicability in the biological and biomedical research.

Single-cell proteomics, nanoscale proteomics, SOP-↗

Detection of impurity diamagnetic susceptibility and its behavior in n-Ge:As in the region of the insulator–metal phase transition

The method of superconducting quantum interference device (SQUID) magnetometry is used to measure and study low-temperature (T ≤ 100K) susceptibility in a series of samples of heavily doped Ge:As samples on the insulator side of the insulator–metal phase transition. Subtracting the known values of the magnetic susceptibility of the lattice from the measurement results, the values of the impurity magnetic susceptibility of the system are obtained. Using the method of electron spin resonance, the paramagnetic component of the impurity susceptibility is determined. Subtraction of the paramagnetic component from the total impurity susceptibility is used to obtain, for the first time, the values of the impurity diamagnetic susceptibility (∼5 × 10{sup –8} cm{sup 3}/g). The obtained result is consistent with estimates obtained for the localization radius of an electron at an As donor. Lowering the temperature to T ≤ 4 K leads to an increase in the diamagnetic susceptibility, which is consistent with the observed increase in the paramagnetic susceptibility. The observed effect is accounted for by the transition of impurity electrons from the singlet state to the triplet one.

36 MATERIALS SCIENCE↗

Nondisruptive Dissolution of Hyperpolarized 129 Xe into Viscous Aqueous and Organic Liquid Crystalline Environments

Studies of hyperpolarized xenon-129 (hp- 129 Xe) in media such as liquid crystals and cell suspensions are in demand for applications ranging from biomedical imaging to materials engineering but have been hindered by the inability to bubble Xe through the desired media as a result of viscosity or perturbations caused by bubbles. In this paper a device is reported that can be reliably used to dissolve hp- 129 Xe into viscous aqueous and organic samples without bubbling. This method is robust, requires small sample volumes (<60 μL), is compatible with existing NMR hardware, and is made from readily available materials. Experiments show that Xe can be introduced into viscous and aligned media without disrupting molecular order. We detected dissolved xenon in an aqueous liquid crystal that is disrupted by the shear forces of bubbling, and we observed liquid-crystal phase transitions in (MBBA). This tool allows an entirely new class of samples to be investigated by hyperpolarized-gas NMR spectroscopy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Scaling of the Stress and Temperature Dependence of the Optical Anisotropy in Ba(Fe 1-x Co x ) 2 As 2

We revisit our recent investigations of the optical properties in the underdoped regime of the title compounds with respect to their anisotropic behavior as a function of both temperature and uniaxial stress across the ferro-elastic tetragonal-to-orthorhombic transition. By exploiting a dedicated pressure device, we can tune and control uniaxial stress in situ thus changing the degree of detwinning of the samples in the orthorhombic SDW state as well as pressure-inducing an orthorhombicity in the paramagnetic tetragonal phase. Here we discover a hysteretic behavior of the optical anisotropy; its stress versus temperature dependence across the structural transition bears testimony to the analogy with the magnetic-field versus temperature dependence of the magnetization in a ferromagnet when crossing the Curie temperature. In this context, we find furthermore an intriguing scaling of the stress and temperature dependence of the optical anisotropy in Ba(Fe 1-x Co x ) 2 As 2 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Cross-slip and easy-glide CRSS in titanium: Theoretical predictions and in-situ TEM measurements

This study investigates the mechanics of prismatic and first-order pyramidal $\langle$a$\rangle$ slip in titanium (Ti), elucidating the physics of easy-glide and cross-slip through a combination of theory and experiments. Screw-character prismatic (Pr) dislocations in Ti are of particular interest because their complex cores can be stable or unstable, leading to activation by either cross-slip or planar glide. To investigate these mechanisms, site-specific micro tensile samples were prepared using focused ion beam (FIB) milling and mounted on a push-to-pull (PTP) device for in-situ transmission electron microscopy (TEM) tensile testing. The in-situ experiments provide direct observations of the onset of dislocation motion and the precise determination of the critical resolved shear stress (CRSS) for the activated mechanisms, and its evolution with load cycling. A comprehensive theory has been developed to predict the CRSS values for easy glide, cross-slip, and multiplication of dislocations. Predicted critical stresses for pyramidal (π)-to-Pr and reverse cross-slip agree closely with the experimental measurements. The latter cross-slip stress is a factor of two higher than that of unobstructed planar slip. The model accounts for overlapping dislocation cores and employs a Wigner-Seitz based cell to evaluate misfit energies. By combining ab initio density functional theory (DFT) with anisotropic elasticity, the framework identifies minimum energy pathways for dislocation glide, which can be intermittent and zig-zag. A simplified expression utilizing (π) and Pr Schmid factor ratios is proposed for critical stress corresponding to (π)-to-Pr cross-slip transition. The results are strongly dependent on crystal orientation, underscoring non-Schmid behavior. Overall, this study explores key critical stress parameters essential for informing higher-scale simulations of plasticity in Ti.

Critical stress↗

Cooking methods and kitchen ventilation availability, usage, perceived performance and potential in Canadian homes

Cooking is a substantial contributor to air pollutant exposures in many residences. Effective use of kitchen ventilation can mitigate exposure; however, information on its availability, usage, and potential to increase its use across the population has been limited. This study aimed to obtain nationally representative information on cooking methods, kitchen ventilation availability and usage, and the potential for education to increase effective usage. An online survey was sent to a representative sample of Canadian homes to collect data on cooking methods, the presence and use of mechanical kitchen ventilation devices, perceived device performance, and willingness to implement mitigation strategies. Responses were weighted to match key demographic factors and analyzed using non-parametric statistics. Among the 4500 respondents, 90% had mechanical ventilation devices over the cooktop (66% of which were vented to the outside), and 30% reported regularly using their devices. Devices were used most often for deep-frying, followed by stir-frying, sautéing or pan-frying, indoor grilling, boiling or steaming. Almost half reported rarely or never using their ventilation devices during baking or oven self-cleaning. Only 10% were fully satisfied with their devices. More frequent use was associated with the device being vented to the outdoors, having more than two speed settings, quiet operation if only one speed, covering over half of the cooktop, and higher perceived effectiveness. After being informed of the benefits of kitchen ventilation, 64% indicated they would consider using their devices more often, preferentially using back burners with ventilation, and/or using higher ventilation device settings when needed. This study provides population-representative data on the most used cooking methods, kitchen ventilation availability and usage, and influencing factors in Canadian homes. Such data are needed for exposure assessments and evaluating the potential to mitigate cooking-related pollutant exposures via more effective use of kitchen ventilation. The data can be reasonably extrapolated to the United States, given the similarities in residential construction practices and cultural norms between the two countries.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Reconfigurable and ultra-sensitive in-line Mach-Zehnder interferometer based on the fusion of microfiber and microfluid

A reconfigurable Mach-Zenhnder interferometer (MZI) based on a microfluidic cavity (MFC) constructed by embedding a microfiber between two segments of single-mode fibers with pre-designed lateral offset has been proposed and experimentally demonstrated. The MFC serves as an interference arm with an eccentric annular cross section and allows convenient sample (gas or liquids) replacement procedure. The microfiber works as the other interference arm that provides the proposed device with ease of reconstruction and also enhances the force sensitivity. The re-configurability and the ultra-wide tuning sensitivity range are demonstrated by immersing the MZI constructed with a 484 μm-long-MFC and a microfiber 44 μm in diameter in different droplets. Ultrahigh sensitivities of 34.65 nm/°C (∼88 380 nm/RIU) and −493.7 nm/N (∼−590 pm/με) are experimentally achieved using a droplet with a refractive index of ∼1.44.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

A novel approach to neutron scattering instrumentation for probing multiscale dynamics in soft and biological matter

We present a concept and ray-tracing simulation results of a mechanical device that will enable inelastic neutron scattering measurements where the data at energy transfers from a few eV to several hundred meV can be collected in a single, gapless spectrum. Besides covering 5 orders of magnitude on the energy (time) scale, the device provides data over 2 orders of magnitude on the scattering momentum (length) scale in a single measurement. Such capabilities are geared primarily toward soft and biological matter, where the broad dynamical features of relaxation origin largely overlap with vibration features, thus necessitating gapless spectral coverage over several orders of magnitude in time and space. Furthermore, neutron scattering experiments with such a device are performed with a fixed neutron final energy, which enables measurements, with neutron energy loss in the sample, at arbitrarily low temperatures over the same broad spectral range. Lastly, this capability is also invaluable in biological and soft matter research, as the variable temperature dependence of different relaxation components allows their separation in the scattering spectra as a function of temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Multi-physics modeling of tungsten collector probe samples during the WEST C4 He campaign

Abstract We describe the results of a multi-scale, multi-physics modeling assessment of SOLPS-ITER, hPIC2, RustBCA and Xolotl, in which five single-crystal tungsten (W) samples were placed in a reciprocating collector probe and exposed to helium (He) plasma in the WEST fusion device. In our models, we considered a pure (100 %) He plasma, as well as one with oxygen (O) present (95% He 5% O) corresponding to the impurity concentration estimated during the C4 He campaign in WEST. Our SOLPS simulations approximately match experimental reciprocating Langmuir probe plasma measurements of plasma density and temperature. Using these plasma parameters as input, hPIC2 and RustBCA predict that the presence of oxygen impurities lead to a 15%–20% decrease in ion and heat fluxes to the surface, and an order of magnitude higher sputtering yields (compared with a pure He plasma). Xolotl predictions for the response of tungsten to plasma surface interactions (PSIs) agree with experimental LAMS analysis, and indicate large near-surface He concentrations, which quickly decay with depth. Our model also shows an increasing role of erosion—in removing the near-surface He—with time. Overall, slightly higher retention is predicted for tungsten exposed to a pure He plasma, with the largest differences in the near-surface gas content caused by the large oxygen-induced erosion. This highlights the important role that impurities play in PSI. Therefore, future work will focus on providing a fully self-consistent description of oxygen (and oxides, etc.) in our models, through multi-species implementation in GITR and inclusion of oxygen and tungsten oxide formation in Xolotl.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Recent DIII-D progress toward validating models of tungsten erosion, re-deposition, and migration for application to next-step fusion devices

Abstract Fundamental mechanisms governing the erosion and prompt re-deposition of tungsten impurities in tokamak divertors are identified and analyzed to inform the lifetime of tungsten plasma-facing components in ITER and other future devices. Various experiments conducted at DIII-D to benchmark predictive models are presented, leveraging the DiMES removable sample exposure probe capability and the Metal Rings Campaign, in which toroidally symmetric rows of tungsten-coated tiles were installed in the DIII-D divertor. In tokamak divertors, the width of the electric sheath is of the order of the main ion Larmor radius, and a vast majority of sputtered tungsten impurities are typically ionized within the sheath. Therefore, W prompt redeposition is mainly governed by the ratio of the characteristic ionization mean-free path of neutral tungsten to the width of the sheath. In-situ monitoring of the prompt redeposition of tungsten impurities in divertors is demonstrated via the use of WII/WI line ratios and the ionizations/photon (S/XB) method in L-mode discharges. Even with this relatively limited set of emission measurements, net erosion measurements were found to be a consistent upper bound to an analytic scaling based on the ratio of the W ionization length, λ iz , and the width of the magnetic sheath rather than the ratio of λ iz and the W + gyro-radius. In the far-scrape-off layer (SOL) of the ITER divertor, however, it is calculated that the measurement of photon emissions associated with the ionization of tungsten impurities up to W 5 + may be required. Finally, W deposition patterns on DiMES collector probes, interpreted via DIVIMP-WallDYN modelling, reveal the key roles of progressive W erosion/re-deposition staps and E × B drifts in regulating long-range high-Z material migration.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Magnetic behaviour studies on nanocrystalline cobalt ferrite by employing the Arrott plot

Vibrating Sample Magnetometer (VSM) has been used to analyze the magnetic behavior of ferrimagnetic material (CoFe{sub 2}O{sub 4}) synthesized by the citric acid modified sol-gel method. X-ray diffraction (XRD) pattern confirms the phase purity of the sample. Its magnetic measurement has been carried out at room temperature in the field range ±1.5T. The magnetocrystalline anisotropy and saturation magnetization of CoFe{sub 2}O{sub 4} are two important parameters which need to be studied for exploring its technological applications like memory device, magnetic sensors etc. Law of Approach (LA) to saturation and the Arrott plot analysis have been carried out to obtain the saturation magnetization. The difference in the saturation magnetization obtained from the two methods gives the qualitative understanding of magnetocrystalline anisotropy and lattice strain present in the sample. The present study explores a new way of analyzing magnetic hysteresis loop of nanocrystalline cobalt ferrite.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Beneficial effect of post-deposition treatment in high-efficiency Cu(In,Ga)Se{sub 2} solar cells through reduced potential fluctuations

World-record power conversion efficiencies for Cu(In,Ga)Se{sub 2} (CIGS) solar cells have been achieved via a post-deposition treatment with alkaline metals, which increases the open-circuit voltage and fill factor. We explore the role of the potassium fluoride (KF) post-deposition treatment in CIGS by employing energy- and time-resolved photoluminescence spectroscopy and electrical characterization combined with numerical modeling. The bulk carrier lifetime is found to increase with post-deposition treatment from 255 ns to 388 ns, which is the longest charge carrier lifetime reported for CIGS, and within ∼40% of the radiative limit. We find evidence that the post-deposition treatment causes a decrease in the electronic potential fluctuations. These potential fluctuations have previously been shown to reduce the open-circuit voltage and the device efficiency in CIGS. Additionally, numerical simulations based on the measured carrier lifetimes and mobilities show a diffusion length of ∼10 μm, which is ∼4 times larger than the film thickness. Thus, carrier collection in the bulk is not a limiting factor for device efficiency. By considering differences in doping, bandgap, and potential fluctuations, we present a possible explanation for the voltage difference between KF-treated and untreated samples.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Low-Noise Amplifiers and Superconducting Flex Circuits for Frequency Domain Multiplexed Readout of Detector Arrays

The next-generation ground-based cosmic microwave background (CMB) experimental program aims to provide definitive measurements of the early universe using telescopes configured with large focal plane arrays requiring ~100,000 detectors and associated readout amplifiers and interconnecting components that are currently unavailable commercially. We describe research to demonstrate the feasibility of developing low-noise cryogenic amplifiers based on series SQUID arrays that are suitable for frequency domain multiplexed readout of large numbers of CMB detectors, and the feasibility of developing robust superconducting flex cables that will simplify cryogenic systems integration for large CMB instruments. Two iterations of prototype series SQUID array amplifier designs were completed. The designs were optimized using modeling and simulation tools to meet the requirements for CMB detector readouts. Two fabrication runs were completed, and a large number of devices from each design iteration were tested and characterized at 4 K. We also completed the development of processes for the fabrication of prototype superconducting flex cables on 4" wafers. Samples were tested for strength and robustness, and to determine the critical current at 4 K as a function of trace width. The new generation of series SQUID array amplifier designs exhibit excellent performance characteristics – very smooth output characteristics that simplify tuning and operation, low input inductance, low current noise referred to the input, and low power dissipation that for the first time will enable these devices to be operated at the focal plane array stage of CMB instruments. The processes developed in Phase I to produce superconducting flex cables were used to complete the fabrication of a full wafer with several test and sample flex circuits. The 6-micron thick flex material is very strong with a breaking strength of several pounds for a 20-mm wide strip. Critical current density was reasonable and scaled with trace width as expected.

79 ASTRONOMY AND ASTROPHYSICS↗

On the design of random metasurface based devices

Metasurfaces are generally designed by placing scatterers in periodic or pseudo-periodic grids. We propose and discuss design rules for functional metasurfaces with randomly placed anisotropic elements that randomly sample a well-defined phase function. By analyzing the focusing performance of random metasurface lenses as a function of their density and the density of the phase-maps used to design them, we find that the performance of 1D metasurfaces is mostly governed by their density while 2D metasurfaces strongly depend on both the density and the near-field coupling configuration of the surface. The proposed approach is used to design all-polarization random metalenses at near infrared frequencies. Challenges, as well as opportunities of random metasurfaces compared to periodic ones are discussed. Our results pave the way to new approaches in the design of nanophotonic structures and devices from lenses to solar energy concentrators.

14 SOLAR ENERGY↗

Hyperdimensional scanning transmission electron microscopy and examinations and related systems, methods, and devices

A material identification system includes one or more data interfaces configured to receive first sensor data generated by a first sensor responsive to a material sample, and receive second sensor data generated by a second sensor responsive to the material sample. The material identification system also includes one or more processors configured to generate a set of predictions of an identification of the material sample and a corresponding set of certainty information.

Aguiar, Jeffery A.↗

Measuring Concentrations of Particulate 140 La in the Air

Air sampling systems were deployed to measure the concentration of radioactive material in the air during the Full-Scale Radiological Dispersal Device experiments. The air samplers were positioned 100-600 meters downwind of the release point. The filters were collected immediately and analyzed in the field. Quantities for total activity collected on the air filters are reported along with additional information to compute the average or integrated air concentrations.

61 RADIATION PROTECTION AND DOSIMETRY↗

TH-AB-209-04: 3D Light Sheet Luminescence Imaging with Cherenkov Radiation

Purpose: To recover a three-dimensional density distribution of luminescent molecular probes located several centimeters deep within a highly scattering tissue. Methods: We developed a novel sheet beam Cherenkov-excited luminescence scanned imaging (CELSI) methodology. The sample was irradiated by a horizontally oriented, vertically scanned 6 MV X-ray sheet beam (200mm × 5mm, 0.2mm vertical step) from a radiotherapy linear accelerator. The resulting Cherenkov light emission – and thus luminescent probe excitation – occurred exclusively along the irradiation plane due to a short diffusion path of secondary particles and Cherenkov photons. Cherenkov-excited luminescence was detected orthogonally to the sheet beam by gated, intensified charge coupled device camera. Analogously to light sheet microscopy, a series of luminescence images was taken for varied axial positions (depths) of the Cherenkov light sheet in sample. Knowledge of the excitation plane position allowed a 3D image stack deconvolution and depth-variant attenuation correction. The 3D image post-processing yielded a true spatial density distribution of luminescent molecules in highly scattering tissue. Results: We recovered a three-dimensional shape and position of 400 µL lesion-mimicking phantom tubes containing 25 µM solution of PtG4 molecular probe from 3 centimeter deep tissue-like media. The high sensitivity of CELSI also allowed resolving 100 micron capillaries of test solution. Functional information of partial oxygen pressure at the site of PtG4 molecular probe was recovered from luminescence lifetime CELSI. Finally, in-vivo sheet beam CELSI localized milimeter-sized PtG4-labelled tumor phantoms in multiple biological objects (hairless mice) from single scan. Conclusion: Presented sheet beam CELSI technique greatly extended the useful depth range of luminescence molecular imaging. More importantly, the light sheet microscopy approach was successfully adapted to CELSI, providing means to recover a completely attenuation-corrected 3D image of luminescent probe distribution. Gated CELSI acquisition yielded functional information of a spatially resolved oxygen concentration map of deep lying targets. This work was supported by NIH research grant R01CA109558 and R21EB017559, as well as by Pilot Grant Funds from the Norris Cotton Cancer Center.

60 APPLIED LIFE SCIENCES↗