Quantitative profiling and pattern analysis of triacylglycerol species in Arabidopsis seeds by electrospray ionization mass spectrometry
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bio-inspired↗
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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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Scaling Properties of the Mean Multiplicity and Pseudorapidity Density in e – +e + , e ± +p, p( p ¯ )+p, p+A and A+A(B) Collisions
The charged-particle pseudorapidity density ( d N ch /dη ) for p( p¯ )+p, p+A and A+A(B) collisions and the mean multiplicity < N ch > for e – +e + , e ± +p , and p( p¯ )+p collisions are studied for a wide range of beam energies ( √s ). Characteristic scaling patterns are observed for both d N ch /dη and < N ch > , consistent with a thermal particle production mechanism for the bulk of the soft particles created in all of these systems. The scaling patterns found also validate an essential role for quark participants in these collisions. The measured values for d N ch /dη and < N ch > are observed to factorize into contributions that depend on log(√s) and the number of nucleon or quark participant pairs N pp . Here the quantification of these contributions gives expressions that serve to systematize d N ch /dη and < N ch > measurements spanning nearly 4 orders of magnitude in s√ and to predict their values as a function of √s and N pp .
74 ATOMIC AND MOLECULAR PHYSICS↗
Nonlinear photorefractive response at high modulation depths
The response of photorefractive materials to sinusoidal intensity patterns of high modulation depths is considered. It is shown that the induced refractive-index response in this regime is highly nonlinear. Concise analytic expressions for the various nonlinear harmonics of the photorefractive response field are developed and compared with exact numerical solutions of the underlying charge-transport equations as well as with the results of previous theoretical models over a broad range of physical parameters. We show that the nonlinear response characteristics are strongly dependent on both the magnitude of applied electric fields and the relative concentrations of charge donor and acceptor sites in the material. For drift dominated recording, in particular, we determine analytically that in the limit of a minimal acceptor/donor ratio, the amplitudes of higher spatial harmonics of the response reach a maximum and eventually decay as functions of increasing applied field, whereas these amplitudes reach a nonzero limit in the case of a near-unity acceptor/donor ratio. Finally, we generalize our results to account for diffusion effects in an appended derivation.
Vachss, Frederick↗
A study of a multi-pinned phase CCD detector for use as a star tracker
This grant has supported studies of the use of charge coupled devices (CCD's) in star trackers in a number of different areas. Among the tasks we have pursued are the following: (1) radiation modeling and the increase in noise equivalent angle as a result of exposure to protons and bremsstrahlung gamma rays; (2) the development of pattern matching software to identify field locations from a CCD image and a pre-existing map of the local area; (3) observations of various stellar fields from the 24 inch telescope at the Offit Observatory at JHU, primarily to test the pattern matching software (these included crowded fields as well as moving objects, like comets); and (4) tracking of very faint objects to determine the faint limit of the CCD system.
Friedman, Scott D.↗
Mass Spectra Deconvolution of Gaseous Mixtures Containing Volatile Organic Compounds
The Spacecraft Atmosphere Monitor (S.A.M.) analyzes all gaseous pollutants in the 1-150Th mass-to-charge range based on their positive-ion mass spectra. Of particular interest is the Trace Gas Analysis (TGA) mode of operation in which S.A.M detects minute amounts of volatile organic compounds (VOC). Pollutant component of the ambient air is sampled on demand in twenty full mass spectra per second. All spectra is accumulated in two-second intervals by an on-board Field Programmable Gate Arrays (FPGA) unit. Mass spectra represents the number of detected fragment ions in a given mass-to-charge ratio channel. Electron impact ionization of neutral molecules results in creation of numerous fragment ions and most of organic compounds will contribute several identical fragments. Despite the presence of these molecular isobars, we developed the deconvolution algorithm capable of identifying target species based on their characteristic fragmentation patterns. We investigate the efficiency of deconvolution algorithm as a function of mass resolution with which mass spectrum is acquired. Higher the mass resolution, better the chances are to distinguish between stereoisomers using their fragmentation propensities, but also results in higher data volumes to be processed by a set of small footprint software stacks hosted by an on-board computer. Finding the balance between deconvolution accuracy and generated data volume under time constrains and limited computing resources is the main topic of this study.
Darrach, M.↗
Spontaneous Formation of Single-Crystalline Spherulites in a Chiral 2D Hybrid Perovskite
In two-dimensional (2D) chiral metal-halide perovskites (MHPs), chiral organic spacers induce structural chirality and chiroptical properties in the metal-halide sublattice. This structural chirality enables reversible crystalline-glass phase transitions in (S-NEA) 2 PbBr 4 , a prototypical chiral 2D MHP where NEA + represents 1-(1-naphthyl)ethylammonium. Here, in this study, we investigate two distinct spherulite states of (S-NEA) 2 PbBr 4 , exhibiting either radial-like or stripe-like banded patterns depending on the annealing conditions of the amorphous film. Despite similarities in optical absorption and photoluminescence, the stripe-like, banded spherulite exhibits higher crystallinity and improved optical transparency compared to those of radial-like spherulite. X-ray nanoprobe measurements reveal tilting-angle modulations in the octahedral plane of stripe-like spherulites, correlating with the film’s surface geometry. Transfer matrix calculations indicate that the optical contrast in stripe-like patterns, seen in bright-field optical microscopy, arises from optical interference effects, differing from the contrast mechanism observed in polymer spherulites. Ultrafast carrier dynamics experiments suggest that the stripe-like spherulites resemble single crystals more closely than radial-like spherulites, while electrical conductivity measurements show enhanced charge carrier transport in stripe-like spherulites. These findings offer insights into MHP spherulite states with a single composition but different morphologies, previously observed only in polymers, highlighting their potential for optoelectronic applications.
36 MATERIALS SCIENCE↗
Temperature dependent dielectric and magnetic properties of GdFe{sub 1−x}Ni{sub x}O{sub 3} (0.0 ≤ x ≤ 0.3) orthoferrites
The polycrystalline samples of GdFe{sub 1−x}Ni{sub x}O{sub 3} (x = 0.0, 0.1, 0.2, 0.3) orthoferrites are synthesized via solid state reaction route. The Rietveld fitted X-ray diffraction patterns confirm the formation of orthorhombic phase with Pbnm space group for all the samples. The dielectric measurements reveal an enhancement in dielectric constant and tangent loss with increase in both temperature as well as Nickel (Ni) substitution. Dielectric studies are also in support with the induction of delocalized charge carriers in the GdFeO{sub 3} matrix with increasing Ni doping. Magnetization versus applied field study shows the non-saturating hysteresis curves suggesting the canted type antiferromagnetic behavior in the considered orthoferrites. Moreover, the observed magnetic behavior is complex and the doping affects the magnitude of magnetization differently at 300 K and 80 K. It has further been noticed that the incorporated Ni{sup 3+} ions enhances the symmetry of the magnetization curves. The as-prepared samples may find their applications in the decoupling capacitors.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Area-selective deposition of germanium on patterned graphene/monolayer molybdenum disulfide stacks via dipole engineering
Heterogeneous integration of two-dimensional materials and the conventional semiconductor has opened opportunities for next-generation semiconductor devices and their processing. Heterogeneous integration has been studied for economical manufacturing by substrate recycling and novel functionalities by a combination of incommensurate materials. However, utilizing the integration requires controlling locations of the integrated architectures. Here, we show area-selective deposition (ASD) of germanium on the graphene/MoS 2 stack. Ge nucleation precisely occurred on the surfaces of the patterned graphene/MoS 2 stack via dipole engineering. In this study, the growth temperature of ASD of Ge was significantly lower than that based on precursor desorption on SiO 2 . The first-principles calculations revealed that Ge deposited by ASD on the graphene/MoS 2 stack was not affected by charge transfer. This work provides a viable way to utilize atomically thin materials for next-generation semiconductor devices, which can be applicable for “Beyond Moore” and “More Moore” approaches.
2D materials↗
Scalable dark matter searches using integrated photonics
Dark matter (DM) with masses of order an electronvolt or below can have a nonzero coupling to electromagnetism while being compatible with cosmological observations. In these models, the ambient DM behaves as a new classical source in Maxwell’s equations, which can excite potentially detectable electromagnetic (EM) fields in the laboratory. We propose a new integrated-photonics–based approach to search for dark matter candidates in the 0.1–few eV mass range. This approach offers a wide range of wavelength-scale devices like resonators and wave guides that are readily fabricated in large quantities, enabling a scalable and novel search. In particular, we demonstrate that refractive index-modulated resonators, such as etched/grooved microrings, or patterned slabs, support EM modes with efficient coupling to DM. When excited by DM, these modes are read out by coupling the resonators to a wave guide that terminates on a micron-scale–sized single photon detector, such as a single pixel of a low-noise charge-coupled device or a superconducting nanowire. We then estimate the sensitivity of this experimental concept in the context of axionlike particle and dark photon models of DM, demonstrating that nanophotonic confinement and scalability can extend dark matter sensitivity into previously unexplored parameter space.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Interface-Driven Chiral Magnetism in Ultrathin Metallic Ferromagnets: Towards Skyrmion Spintronics
Magnetic skyrmions are localized chiral magnetic textures in the form of nanoscale vortices or bubbles that are topologically protected from being ‘unwound’. Their topological nature gives rise to rich behaviors including ordered lattice formation, emergent electrodynamics and robust current-driven displacement at remarkably low current densities. However, magnetic skyrmions have so far been restricted to just a few materials and observed only at low temperatures, limiting the experimental accessibility and technological application of these unique topological objects. This project aimed to realize magnetic skyrmions at room temperature in a new class of engineered chiral ferromagnets that exploit broken mirror symmetry at interfaces to generate helical magnetic order. Ultrathin magnetic heterostructures were engineered and patterned into laterally-confined nanostructures in which skyrmions were stabilized, manipulated, and detected for the first time under ambient conditions. Static and dynamic properties were examined using advanced x-ray imaging to provide a fundamental understanding of topological magnetic phases. The interactions between magnetic skyrmions and electron charge and spin currents were studied to identify fundamental new physics and enable device applications. These experimental studies, supported by detailed modeling, will help launch a new subfield of skyrmion-based spintronics in which individual skyrmions can be used to encode, store, and transport information in high-performance, low power memory and logic devices.
36 MATERIALS SCIENCE↗
Branched High Aspect Ratio Nanostructures Fabricated by Focused Helium Ion Beam Induced Deposition of an Insulator
Helium ion beam induced deposition using the gaseous precursor pentamethylcyclopentasiloxane is employed to fabricate high aspect ratio insulator nanostructures (nanopillars and nanocylinders) that exhibit charge induced branching. The branched nanostructures are analyzed by transmission electron microscopy. It is found that the side branches form above a certain threshold height and that by increasing the flow rate of the precursor, the vertical growth rate and branching phenomenon can be significantly enhanced, with fractalesque branching patterns observed. The direct-write ion beam nanofabrication technique described herein offers a fast single-step method for the growth of high aspect ratio branched nanostructures with site-selective placement on the nanometer scale.
36 MATERIALS SCIENCE↗
Electron-beam lithography for micro and nano-optical applications
Direct-write electron-beam lithography has proven to be a powerful technique for fabricating a variety of micro- and nano-optical devices. Binary E-beam lithography is the workhorse technique for fabricating optical devices that require complicated precision nano-scale features. We describe a bi-layer resist system and virtual-mark height measurement for improving the reliability of fabricating binary patterns. Analog E-beam lithography is a newer technique that has found significant application in the fabrication of diffractive optical elements. We describe our techniques for fabricating analog surface-relief profiles in E-beam resist, including some discussion regarding overcoming the problems of resist heating and charging. We also describe a multiple-field-size exposure scheme for suppression of field-stitch induced ghost diffraction orders produced by blazed diffraction gratings on non-flat substrates.
electron-beam lithography↗
NASA Tech Briefs, January 2008
Topics covered include: Induction Charge Detector with Multiple Sensing Stages; Generic Helicopter-Based Testbed for Surface Terrain Imaging Sensors; Robot Electronics Architecture; Optimized Geometry for Superconducting Sensing Coils; Sensing a Changing Chemical Mixture Using an Electronic Nose; Inertial Orientation Trackers with Drift Compensation; Microstrip Yagi Antenna with Dual Aperture-Coupled Feed; Patterned Ferroelectric Films for Tunable Microwave Devices; Micron-Accurate Laser Fresnel-Diffraction Ranging System; Efficient G(sup 4)FET-Based Logic Circuits; Web-Enabled Optoelectronic Particle-Fallout Monitor; SiO2/TiO2 Composite for Removing Hg from Combustion Exhaust; Lightweight Tanks for Storing Liquefied Natural Gas; Hybrid Wound Filaments for Greater Resistance to Impacts; Making High-Tensile-Strength Amalgam Components; Bonding by Hydroxide-Catalyzed Hydration and Dehydration; Balanced Flow Meters without Moving Parts; Deflection-Compensating Beam for Use inside a Cylinder; Four-Point-Latching Microactuator; Curved Piezoelectric Actuators for Stretching Optical Fibers; Tunable Optical Assembly with Vibration Dampening; Passive Porous Treatment for Reducing Flap Side-Edge Noise; Cylindrical Piezoelectric Fiber Composite Actuators; Patterning of Indium Tin Oxide Films; Gimballed Shoulders for Friction Stir Welding; Improved Thermal Modulator for Gas Chromatography; Nuclear-Spin Gyroscope Based on an Atomic Co-Magnetometer; Utilizing Ion-Mobility Data to Estimate Molecular Masses; Optical Displacement Sensor for Sub-Hertz Applications; Polarization/Spatial Combining of Laser-Diode Pump Beams; Spatial Combining of Laser-Diode Beams for Pumping an NPRO; Algorithm Optimally Orders Forward-Chaining Inference Rules; Project Integration Architecture; High Power Amplifier and Power Supply; Estimating Mixing Heights Using Microwave Temperature Profiler; and Multiple-Cone Sunshade for a Spaceborne Telescope.
Source record↗
Local electric field direct writing – Electron-beam lithography and mechanism
Local electric field induced by a focused electron probe in silicate glass thin films is evaluated in this paper by the migration of cations. Extremely strong local electric fields can be obtained by the focused electron probe from a scanning transmission electron microscope. As a result, collective atomic displacements occur. This newly revised mechanism provides an efficient tool to write patterned nanostructures directly, and thus overcome the low efficiency of the conventional electron-beam lithography. Applying this technique to silicate glass thin films, as an example, a grid of rods of nanometer dimension can be efficiently produced by rapidly scanning a focused electron probe. This nanopatterning is achieved through swift phase separation in the sample, without any post-development processes. The controlled phase separation is induced by massive displacements of cations (glass modifiers) within the glass-former network, driven by the strong local electric fields. The electric field is induced by accumulated charge within the electron probed region, which is generated by the excitation of atomic electrons by the incident electron. Throughput is much improved compared to other scanning probe techniques. Finally, the half-pitch spatial resolution of nanostructure in this particular specimen is 2.5 nm.
36 MATERIALS SCIENCE↗
Patternable, Solution-Processed Ionogels for Thin-Film Lithium-Ion Electrolytes
Not Available
bio-inspired, energy storage (including batteries ↗
Development of HPWH System Model, Using All Microchannel Heat Exchangers
In this report, 24-hour energy factor (EF) and first-hour draw rating (FHR) simulations were conducted on two heat pump water heater systems (HPWHs), one using a fin-and-tube evaporator and wrapped-tank condenser coil with D-shape tubes, and the other using a micro-channel evaporator and wrapped-tank condenser coil with microchannel tubes. Alternative refrigerants as drop-in replacements of R-134a were evaluated, including R-1234yf, R-1234ze(E), propane (R-290), R-450A and R-513A. The results are summarized below: 1.Microchannel heat exchangers can decrease the system charge down to 30% relative to fin-and-tube evaporator and wrapped-tank D tubes.2.Having the same contact surface area to the water tank and evaporator frontal flow area, the system using microchannel heat exchangers (MHXs) results in 5% efficiency degradation. Due to the very small cross-sectional flow area of a microchannel tube, MHXs tend to have multiple parallel tubes to restrict the refrigerant pressure drop. The parallel pattern can’t utilize the water temperature stratification as effectively as the D-shape tubes, which are arranged in one or two circuits and counter flow to the water stratification. 3.Refrigerant drop-in system simulations were conducted for R-1234yf, R-1234ze(E), propane, R450A and R513A in comparison to R-134a. Among the alternatives, propane has the largest volumetric capacity, which results in shortest HPWH run time and highest first-hour rating. Propane leads to the smallest energy factor because its largest volumetric capacity overloads the heat exchangers. R-1234ze(E) has the smallest volumetric capacity, highest energy factor, but smallest first-hour rating. R-1234yf, R-450A and R-513A achieve similar performance indices as R-134a. 4.Propane requires the least refrigerant mass (45% relative to R-134a). If a wrapped-tank microchannel condenser and microchannel evaporator are used, the required system charge can be limited below 150 grams, which makes it feasible to use propane for domestic HPWH.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Using Scanning-Probe Block Copolymer Lithography and Electron Microscopy To Track Shape Evolution in Multimetallic Nanoclusters
Here we describe a general method for synthesizing multimetallic core–shell nanoclusters on surfaces. By patterning seeds at predesignated locations using scanning-probe block copolymer lithography, we can track shape evolution in nanoclusters and elucidate their growth pathways using electron microscopy. The growth of core–shell nanostructures on surface-bound seeds is a highly anisotropic process and often results in multimetallic anisotropic nanostructures. Lastly, the shell grows at specific edge and corner sites of the patterned seeds and propagates predominately from the top hemisphere of the seeds.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Role of calcination atmosphere in vanadium doped Li{sub 4}Ti{sub 5}O{sub 12} for lithium ion battery anode material
Highlights: • First comparison on V doped Li{sub 4}Ti{sub 5}O{sub 12} (VLTO) synthesized in air and argon. • Ti{sup 4+} do not reduce to Ti{sup 3+} in air calcined VLTO. • V doping enhances reducing of Ti{sup 4+} to Ti{sup 3+} in argon calcined VLTO. • Li{sub 4}Ti{sub 4.9}V{sub 0.1}O{sub 12} calcined in argon shows best charge-discharge behaviors. • Conductivity enhancement in argon calcined VLTO upto three orders. - Abstract: Li{sub 4}Ti{sub 5}O{sub 12} (LTO) with enhanced properties can replace the conventional carbonaceous anode material of lithium ion battery. Vanadium doped LTO (Li{sub 4}Ti{sub 5-x}V{sub x}O{sub 12}, x = 0, 0.05, 0.1, 0.15) materials are synthesized by sol-gel process followed by calcination of dried gel in air and argon atmosphere. No additional phase corresponding V is indicated in XRD patterns. Calcination in argon reduces the particle size of Li{sub 4}Ti{sub 5-x}V{sub x}O{sub 12} while V doping reduces particle size distribution. XPS reveals that Ti{sup 4+} get reduced to Ti{sup 3+} only in argon calcined Li{sub 4}Ti{sub 5-x}V{sub x}O{sub 12} which is enhanced by V doping. Electrochemical impedance spectroscopy confirms that compared to LTO, lithium ion diffusion coefficient of air and argon calcined Li{sub 4}Ti{sub 4.85}V{sub 0.15}O{sub 12} is approximately two and three times higher. Argon calcined Li{sub 4}Ti{sub 4.9}V{sub 0.1}O{sub 12} shows highest charge-discharge capacities at almost all C-rates (0.1 to 5C; 1C = 175mAg{sup −1}). Electronic conductivity of argon calcined Li{sub 4}Ti{sub 4.9}V{sub 0.1}O{sub 12} is 1.7 × 10{sup −2} S cm{sup −1} which is three orders higher than that of LTO.
36 MATERIALS SCIENCE↗