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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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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Simple non-perturbative resummation schemes beyond mean-field: case study for scalar $\phi^4$ theory in 1+1 dimensions

I present a sequence of non-perturbative approximate solutions for scalar $\phi^4$ theory for arbitrary interaction strength, which contains, but allows to systematically improve on, the familiar mean-field approximation. This sequence of approximate solutions is apparently well-behaved and numerically simple to calculate since it only requires the evaluation of (nested) one-loop integrals. To test this resummation scheme, the case of $\phi^4$ theory in 1+1 dimensions is considered, finding approximate agreement with known results for the vacuum energy and mass gap up to the critical point. Because it can be generalized to other dimensions, fermionic fields and finite temperature, the resummation scheme could potentially become a useful tool for calculating non-perturbative properties approximately in certain quantum field theories.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Cancer Immunotherapy: A Simple Guide for Interventional Radiologists of New Therapeutic Approaches

The therapeutic options in the treatment of cancer therapy have been recently significantly increased with systemic immune-targeted therapies. Novel immunotherapy approaches based on immune checkpoint blockade or engineered cytotoxic T lymphocytes have reached late-stage clinical development, with highly encouraging results. The success of cancer immunotherapy has generated a tremendous interest in further developing and exploring these strategies in combination with other approaches such as radiotherapy and local ablative therapies in oncology. The goal of this review is to discuss current approaches in immunotherapy and provide simple and constructive explanations on their mechanisms of action as well as certain more common and serious toxicities.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

H-D Exchange of Simple Aromatics as a Measure of Brønsted-Acid Site Strengths in Solids

The relative Brønsted-acid strengths of H-[Al]ZSM-5, H-[Fe]ZSM-5, H-[B]ZSM-5, silicalite, P-SPP, tungstated zirconia, ZrO2, and γ-Al2O3 were studied using H-D exchange with toluene and chlorobenzene. Temperature programmed desorption (TPD) of toluene-h8 and chlorobenzene-h5 from the deuterated forms of H-[Al]ZSM-5, H-[Fe]ZSM-5, and P-SPP demonstrated that the temperature at which H-D exchange rates become significant change with the proton affinity of the aromatic molecule and the strength of the Brønsted sites. The steady-state, gas-phase reaction between D2O and the aromatic molecules were consistent with the TPD results and allowed the Brønsted-acid site strengths to be ordered as follows: H-[Al]ZSM-5 > H-[Fe]ZSM-5 > tungstated zirconia > P-SPP > H-[B]ZSM-5. H-D exchange was also observed at high temperatures with ZrO2 and γ-Al2O3 but it appears that the reaction mechanism with these Lewis acids is different because reaction with toluene and chlorobenzene occur at nearly the same temperature. It is suggested that the H-D exchange reaction with simple aromatic molecules is a useful way to probe Brønsted acidity in solids

bio-inspired↗
DOE OSTI2015

Simple Expressions for the Design of Linear Tapers in Overmoded Corrugated Waveguides

In this paper, simple analytical formulae are presented for the design of linear tapers with very low mode conversion loss in overmoded corrugated waveguides. For tapers from waveguide radius a2 to a1, with a1 1 a 2 /λ. Here, λ is the wavelength of radiation. The fractional loss of the HE 11 mode in an optimized taper is 0.0293(a 2 -a 1 ) 4 /a$2\atop{1}$1a$2\atop{2}$. These formulae are accurate when a2≲2a 1 . Slightly more complex formulae, accurate for a 2 ≤4a 1 , are also presented in this paper. The loss in an overmoded corrugated linear taper is less than 1 % when a 2 ≤2.12a 1 and less than 0.1 % when a 2 ≤1.53a 1 . The present analytic results have been benchmarked against a rigorous mode matching code and have been found to be very accurate. The results for linear tapers are compared with the analogous expressions for parabolic tapers. Finally, parabolic tapers may provide lower loss, but linear tapers with moderate values of a 2 /a 1 may be attractive because of their simplicity of fabrication.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Novel Biodegradable Thermoplastic Elastomer Based on Poly(butylene succinate) and Epoxidized Natural Rubber Simple Blends

Novel biodegradable thermoplastic elastomer based on epoxidized natural rubber (ENR) and poly(butylene succinate) (PBS) blend was prepared by a simple blend technique. Influence of blend ratios of ENR and PBS on morphological, mechanical, thermal and biodegradable properties were investigated. In addition, chemical interaction between ENR and PBS molecules was evaluated by means of the rheological properties and infrared spectroscopy. Furthermore, the phase inversion behavior of ENR/PBS blend was predicted by different empirical and semi-empirical models including Utracki, Paul and Barlow, Steinmann and Gergen models. It was found that the co-continuous phase morphology was observed in the blend with ENR/PBS about 58/42 wt% which is in good agreement with the model of Steinmann. This correlates well to morphological and mechanical properties together with degree of crystallinity of PBS in the blends. In addition, the biodegradability was characterized by soil burial test after 1, 3 and 9 months and found that the biodegradable ENR/PBS blends with optimum mechanical and biodegradability were successfully prepared.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Simple Hydrothermal Synthesis for Mesoporous Pebble-Like NiCo{sub 2}O{sub 4} Nanostructures and Their Attractive Magnetic Properties

The mesoporous pebble-like NiCo{sub 2}O{sub 4} nanostructures were smoothly obtained via a simple hydrothermal route and the succeeding annealing treatment. Various techniques, including XRD, SEM, TEM, Raman spectra, FTIR, and MH curves have been used to study the obtained products. The obtained results exhibited that the morphology of spinel NiCo{sub 2}O{sub 4} could be controlled by adjusting the content of cetyltrimethylammonium bromide (CTAB). The morphology of NiCo{sub 2}O{sub 4} nanostructures transformed from a 300-nm popcorn-like to 30–40-nm pebble-like nanostructure by changing the content of CTAB. Compared with the popcorn-like NiCo{sub 2}O{sub 4} nanostructures, the pebble-like samples showed effective blue shifting of Raman spectroscopy, which might be due to the nano-sized effect of NiCo{sub 2}O{sub 4} particles. Finally, vibration sample magnetometer (VSM) measurements indicated the samples transformed from weak ferromagnetic (popcorn-like) to paramagnetic (pebble-like) due to small particle size.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

A Simple Kinetic Model for the Phase Transition of the van der Waals Fluid

A simple kinetic model, which is presumably minimum, for the phase transition of the van der Waals fluid is presented. In the model, intermolecular collisions for a dense gas has not been treated faithfully. Instead, the expected interactions as the non-ideal gas effect are confined in a self-consistent force term. Collision term plays just a role of thermal bath. Accordingly, it conserves neither momentum nor energy, even globally. It is demonstrated that (i) by a natural separation of the mean-field self-consistent potential, the potential for the non-ideal gas effect is determined from the equation of state for the van der Waals fluid, with the aid of the balance equation of momentum, (ii) a functional which monotonically decreases in time is identified by the H theorem and is found to have a close relation to the Helmholtz free energy in thermodynamics, and (iii) the Cahn–Hilliard type equation is obtained in the continuum limit of the present kinetic model. Numerical simulations based on the Cahn–Hilliard type equation are also performed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

On One Numerical-Analytic Method for the Solution of One-Dimensional Quasistatic Problems of Thermoelasticity for Thermosensitive Bodies of Simple Geometry

We propose a procedure for the numerical-analytic solution of one-dimensional problems of thermoelasticity for bodies of simple geometry based on the representation of temperature dependences of the physicomechanical characteristics of materials in the form of piecewise constant functions of temperature and the application of the Kirchhoff substitution and the methods of generalized functions. This procedure enables us to study one-dimensional nonstationary thermal and quasistatic stress-strain states under the combined thermal and force action with controlled reliability.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Simple 14-Dimensional Lie Algebras in Characteristic Two

Using theory of deformations of Lie algebra of type G{sub 2}, isomorphisms between the known simple 14-dimensional Lie algebras over a field of even characteristic and Lie algebras of Cartan type of S or H are constructed.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Simple separation of technetium from molybdenum for tracer isotope production

A procedure for the separation of technetium isotopes from bulk molybdenum was developed in nitric acid media. After irradiation of nat Mo foils, and dissolution in H 2 O 2 , the solution is acidified to 2 M HNO 3 , and anion exchange resin is used to separate technetium from molybdenum. The procedure is simple, requiring only basic laboratory equipment and, with a two-column separation, the technetium yield is high (~ 85%) with extremely high purity (< 0.1 ppm nat Mo). In conclusion, this is ideally suited for laboratory production of technetium tracer isotopes, particularly 95m Tc.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

A simple amplitude decision based symbol timing synchronization method for real-time IMDD-OOFDM systems

A simple amplitude decision based symbol timing synchronization method for real-time IMDD-OOFDM transmission systems is proposed and experimentally evaluated by using directly modulated DFB laser in 25 km SSMF. The experimental results show that the hardware resource consumption of the proposed synchronization technique is only 6% of the total system which can effectively release the computation complexity without sacrificing the synchronization accuracy. Less than 2 samples offset error of synchronization accuracy can be achieved at received optical power as low as − 20 dBm without employing correlation and multiplication operations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Continual–quantum plasmonics with kinematical functions: dipolar resonance and nonlocal polarizability of simple metal made nanoparticles

In this work we formulate the theory of a mesoscopic oscillator equivalent to sp-electron excitations in simple metal made nanoparticles illuminated by incident light. The principles of continuum mechanics have been applied to maintain this goal: the primary hypotheses about the dependences of electron density function upon kinematical generalized coordinates, the stationary action principle, and the perturbation method. On their grounds, dynamic equations describing the motion of electron gas subject to alternating potentials together with the ground state equations have been derived. A methodological advantage of the latter is in the correct (qualitative and quantitative) prediction of Friedel oscillations and electron spill-out through an ion lattice with no demands to use high power computer resources as opposed to the orbital density functional theory. The dynamic equations allow studying of the nanoparticle resonant properties in an analytical form without need of numerically solving them. It has been shown with their use that the resonant frequency of the main dipolar resonance becomes the density functional of the ground state. On the basis of the dynamic equations, the theory of nonlocal polarizability has been deduced that does not impose the homogeneity (or weak inhomogeneity) constraints on the electron gas density. In this context the two following results are of importance. We manage to: (1) to demonstrate the effect of giant nonlocality of the dipole moment—its formation by the events separated by distances significantly larger than nanoparticle dimensions and temporal intervals much larger than the mean free time; (2) to derive the expression of the volumetric mode of compression-tension that is resonant on frequency of the main dipolar resonance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

A simple design of highly birefringent and nonlinear photonic crystal fiber with ultra-flattened dispersion

We present a compressed hexagonal photonic crystal fiber (CH-PCF) based on a simple structure with ultra-flattened dispersion, high birefringence and nonlinearity. The propagation characteristics are studied accurately by utilizing full vector finite-element method (FEM). Numerical results indicate that the birefringence of 1.59 × 10{sup −2} was obtained with high nonlinear coefficient of 42.58 W{sup −1} km{sup −1}(X) and 52.80 W{sup −1} km{sup −1}(Y) at an effective wavelength of 1.55 μm. Furthermore, CH-PCF presents an ultra-flattened dispersion with variation of ± 3.4 ps/nm/km(X) and ± 1.6 ps/nm/km(Y) over 1.3 μm to 1.8 μm (0.5 μm bandwidth), respectively. In addition, this circular-hole structure can be fabricated conveniently at most easy compared with complex designs, which is an advantage for practical applications such as dispersion compensation and nonlinear optics application.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

CO 2 supplementation eliminates sugar-rich media requirement for plant propagation using a simple inexpensive temporary immersion photobioreactor

In vitro plant propagation systems such as temporary immersion bioreactors (TIBs) are valuable tools that enable production of disease-free plants with improved traits. However, TIB systems can be expensive, difficult to implement, and prone to contamination due to sugar rich propagation media. Using rapidly growing chicory root cultures to expedite design-build-test cycles, we report here an improved, low-cost version of a previously reported Hydrostatically-driven TIB (Hy-TIB) that facilitates economical use of gas mixtures. Bioreactor improvements include decreased material costs, expanded modes of operation, and a horizontal orientation of a plastic film plant growth chambers that increase propagule light exposure. To take advantage of these improvements, we describe here experiments that evaluate the impacts of elevated CO 2 on propagation of cacao (Theobroma cacao) secondary embryos and nodal cultures of yam (Dioscorea spp.) during both phototrophic and photomixotrophic growth. Our experiments show that elevated CO 2 during plant propagation significantly improved both cacao and yam propagule development and eliminated the need for supplemental sugars in tissue culture growth media. Thus, our improved Hy-TIB shows potential as a simple, low-cost, and scalable propagation platform with cost-effective gas composition control and reduced risk of contamination overgrowth. We provide detailed instructions for assembly of this Hy-TIB design and discuss the implications of its adoption in food-insecure regions of the world.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

A Simple Analytical Model for Predicting the Detectable Ion Current in Ion Mobility Spectrometry Using Corona Discharge Ionization Sources

Corona discharge ionization sources are often used in ion mobility spectrometers (IMS) when a non-radioactive ion source with high ion currents is required. Typically, the corona discharge is followed by a reaction region where analyte ions are formed from the reactant ions. In this work, we present a simple yet sufficiently accurate model for predicting the ion current available at the end of this reaction region when operating at reduced pressure as in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) or most IMS-MS instruments. It yields excellent qualitative agreement with measurement results and is even able to calculate the ion current within an error of 15%. Additional interesting findings of this model are the ion current at the end of the reaction region being independent from the ion current generated by the corona discharge and the ion current in High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) growing quadratically when scaling down the length of the reaction region. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Impact of Ceramic Substrates Geometry on the Performance of Simple Thermo-Acoustic Engines

This work experimentally examines the influence of the stack geometry and position on the performance of thermo-acoustic engines (TAE). Twenty cordierite honeycomb ceramic stacks with square pores and five different lengths (7, 13, 17, 22 and 25 mm) were considered. Measurements were taken at seven different locations of the stack hot ends from the pressure antinode (closed end), namely 52, 72, 92,112, 132, 152 and 172 mm respectively. The temperature difference across the stack and radiated sound pressure level at steady state are considered indicators of the performance of the device. The results obtained with a simple standing wave thermo-acoustic engine used in this experiment reveals that the relationships between the length, the stack pores sizes and the input power are non-linear. In addition, the effect of the viscous resistance and the thermal losses were confirmed to be strong enough when the input heating power is low.

42 ENGINEERING↗