Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “electronic transformers”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Alendronate functionalized mesoporous hydroxyapatite nanoparticles for drug delivery

Highlights: ► The synthesized mesoporous hydroxyapatite has nanostructure and bioactivity. ► The materials have high surface area and amino group. ► The materials show higher drug loading and slower release rate than pure HAP. - Abstract: Mesoporous nanosized hydroxyapatite (HAP) functionalized by alendronate (ALN) was synthesized using cationic surfactant CTAB as template. The structural, morphological and textural properties were fully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and N{sub 2} adsorption/desorption. Then the obtained materials were performed as drug delivery carriers using ibuprofen (IBU) as a model drug to investigate their drug storage/release properties in simulated body fluid (SBF). The materials showed relatively slower release rate compared with HAP due to the ionic interaction between -NH{sub 3}{sup +} on the matrix and -COO{sup −}belongs to IBU. The system provides a new concept for improving the drug loading or slowing down the release rate.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Vanadium oxides nanostructures: Hydrothermal synthesis and electrochemical properties

Highlights: • Vanadium oxides nanostructures were synthesized hydrothermally. • Reversible redox behavior with doping/dedoping process. • Doping/dedoping is easier for Li{sup +} to Na{sup +}. • Energy-related applications such as cathodes in lithium batteries. - Abstract: A facile and template-free one-pot strategy is applied to synthesize nanostructured vanadium oxide particles via a hydrothermal methodology. X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) have been used to characterize the structure and morphology of the samples. The products are gradually changed from sheet-shaped VO{sub 2}(B) to rod-like V{sub 3}O{sub 7}·H{sub 2}O with decreasing cyclohexanediol as both protective and reducing agent. The specific surface area of the VO{sub 2}(B) nanosheets and V{sub 3}O{sub 7}·H{sub 2}O nanorods was found to be 22 and 16 m{sup 2} g{sup −1}, respectively. Thin films of VO{sub 2}(B) and V{sub 3}O{sub 7}·H{sub 2}O deposited on ITO substrates were electrochemically characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The voltammograms show reversible redox behavior with doping/dedoping process corresponding to reversible cation intercalation/de-intercalation into the crystal lattice of the nanorods/nanosheets. This process is easier for the small Li{sup +} cation than larger ones Na{sup +}.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fabrication and characterization of electrospun single-crystal lead manganese borate nanofibers

Highlights: • Single crystal PbMnBO4 nanofibers were successfully fabricated by electrospinning process. • The PbMnBO4 nanofibers synthesized for the first time and unprecedented in the literature. • Characterization of PbMnBO{sub 4} nanofibers in mineralogical, optical and thermal properties was revealed. • The nanofibers exhibit single crystalline features with an average size between 120 and 250 nm. • These nanofibers can be used in optic or photonic fields as a flexible sensor due to its nonlinear and ferromagnetic properties. - Abstract: Anhydrous borate compounds are important materials in optical applications as nonlinear optical materials (NLO), due to the presence of structural B{sub x}O{sub y} subunits. Herein, lead manganese borate (PbMnBO{sub 4}) nanofibers have been firstly fabricated via a facile approach using a simple and inexpensive electrospinning technique. All of the synthesized samples were analyzed with X-Ray Diffractometer (XRD), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and Ultraviolet-visible Spectroscopy (UV–vis) method. In addition, they were thermally analyzed with Thermal Gravimetric and Differential Thermal Analyzer and TG-DTA diagrams were discussed in detail. All of the characterization results showed that the obtained PbMnBO{sub 4} nanostructures have nanofiber structures and good crystalline features. PbMnBO{sub 4} nanofiber synthesized for the first time and unprecedented in the literature is promising absorber materials for nonlinear optic applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Synthesis of Fe3O4/Pr-BiOCl/Luffa composites with enhanced visible light photoactivity for organic dyes degradation

Highlights: • Fe{sub 3}O{sub 4}/Pr-BiOCl/Cellulose photocatalysts were synthesized for the first time. • The Fe{sub 3}O{sub 4}/Pr-BiOCl/Cellulose photocatalysts have high photoactivity and stability. • The optimal Pr loading was 0.1%. • The Fe{sub 3}O{sub 4}/Pr-BiOCl/Cellulose photocatalysts are easy to separate from the reaction system. - Abstract: Fe{sub 3}O{sub 4}/Pr-BiOCl/Luffa (FPBL) composites were successfully prepared for the first time via a two-step synthesis method. The composites were characterized by a number of techniques including XRD, FTIR, SEM, DRS, BET, XPS, PL, UV–vis and VSM. The photocatalytic activity of FPBL was further evaluated through the photodegradation efficiency of Rhodamine B (RhB). Almost all RhB was removed after 120 min visible light irradiation in the present of the FPBL. The effects of dose and pH were also studied, and the best performance was achieved at pH 6 while the dose of as-prepared photocatalyst was 1.0 g/L. The as-prepared photocatalyst can be magnetically recycled, and it maintained high photocatalytic activity after six-cycle of photodegradation. The free radical trapping experiments demonstrated that the holes (h{sup +}) and electrons (e{sup −}) were two main active species in the photocatalytic degradation of RhB. This work suggests the Fe{sub 3}O{sub 4}/Pr-BiOCl/Luffa composites are promising photocatalysts for organic pollutant degradation.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets

An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Effect of Silicon Content on the Hardenability and Mechanical Properties of Link-Chain Steel

Heavy-section link-chains are increasingly required to satisfy industrial demands of shipping, lifting, and mining machinery. In this study, the hardenability of link-chain steels with different Si contents was investigated using end-quench tests. The microstructures of the end-quenched specimens were examined by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The mechanical properties were investigated by tension tests and impact tests. The effect of the Si content on the phase-transformation temperature during cooling was analyzed by differential scanning calorimetry. It was found that increasing the Si content from 0.24 to 0.74% led to a significant increase in hardenability; the ideal diameter (i.e., the diameter of given steel that would produce 50% martensite at the center when quenched in a hypothetical quenching medium that reduces the surface temperature of the heated steel to the bath temperature in zero time) increased from 187 to 248 mm. Si enhances the hardenability of link-chain steel by affecting its phase-transition behaviors during cooling, including suppressing ferrite formation, inhibiting carbide precipitation, and lowering the temperature of maximum transformation of bainite. The suggested Si content is 0.70-0.75% to produce link-chain steel with high hardenability and good mechanical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Diabatization based on the dipole and quadrupole: The DQ method

In this work, we present a method, called the DQ scheme (where D and Q stand for dipole and quadrupole, respectively), for transforming a set of adiabatic electronic states to diabatic states by using the dipole and quadrupole moments to determine the transformation coefficients. It is more broadly applicable than methods based only on the dipole moment; for example, it is not restricted to electron transfer reactions, and it works with any electronic structure method and for molecules with and without symmetry, and it is convenient in not requiring orbital transformations. We illustrate this method by prototype applications to two cases, LiH and phenol, for which we compare the results to those obtained by the fourfold-way diabatization scheme.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Effects of Sintering Temperature on Structural, Morphological and Magnetic Properties of Strontium Ferrite Nanoparticles

In the present investigation, structural, morphological and magnetic properties of SrFe{sub 2}O{sub 4} ferrite nanoparticles prepared by a sol–gel method were studied. The techniques used in this investigation were thermogravimetric analysis/differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FT-IR), vibrating sample magnetometry (VSM) and Curie temperature analysis. The average crystallite sizes of the SrFe{sub 2}O{sub 4} were calculated using the Scherrer formula and found in the range of 11–22 nm, and this can be attributed to the grain growth of the particles. The lattice parameter of SrFe{sub 2}O{sub 4} nanoparticles decreased from 6.64 to 6.51 nm as the sintering temperature was raised from 600 to 900 °C. FT-IR analysis confirmed that bands in the range 430–590 cm{sup − 1} are due to the stretching vibration of oxygen atom and metal ions (M–O) that is Fe–O confirming the formation of spinel ferrite. Surface morphology of the samples has been studied using FESEM. The elemental composition along with their relative ratios was given by EDX and was found to be in agreement with their initial calculated values. The saturation magnetization, magnetic coercivity and remanence increase with an increasing sintering temperature from 600 to 900 °C. The present study reports the Curie temperature with an amount of 551 °C of the synthesized strontium nanoferrites using the Faraday technique.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Effect of MWCNT Content on the Structure and Properties of Spark Plasma-Sintered Iron-MWCNT Composites Synthesized by High-Energy Ball Milling

The effect of multiwall carbon nanotube (MWCNT) content on the physical and mechanical properties of Fe-MWCNT composites has been studied. High-energy ball milling (HEBM) is employed to produce the composite powder; following this, spark plasma sintering (SPS) process has been adopted for powder consolidation. The composite powder and the sintered products were subjected to structural characterization by XRD. Microstructural studies were carried out by optical, field-emission scanning and high-resolution transmission electron microscopy. While Fourier transform infrared spectroscopic study of composites was done to understand the bonding characteristics, Raman spectroscopy was employed to assess the structural damage of MWCNT after HEBM. The effects of processing on the behavior of C-C, C-O and Fe-O bonds are studied by x-ray photoelectron spectroscopy. Microhardness and compressive strength of composites are also determined. Finally, magnetic and electrical properties of the composites were characterized. It was observed that optimized ball milling conditions help to preserve the structural identity of MWCNT. Consolidation by SPS insured good interfacial bonding. The microhardness and compression strength are significantly improved in MWCNT-reinforced iron matrix composite. MWCNT has appreciably improved the electrical conductivity of the composites. Tethering of MWCNT by iron oxide has led to appreciable improvement in saturation magnetization till 3 wt.% MWCNT.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The removal of Zn2+, Pb2+, and As(V) ions by lime activated fly ash and valorization of the exhausted adsorbent

This study focuses on the use of raw fly ash (FA) and modified fly ash – activated by lime (MFA), as effective and low-cost adsorbents for the removal of heavy metals (Zn2+, Pb2+and As(V)), followed by the revalorization of the exhausted adsorbent. The granulometric, elemental analysis, point of zero charge (pHPZC), radiochemical and structural characterization were conducted using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and gamma spectrometry techniques. The optimal conditions and key factors influencing the adsorption process were assessed using the response surface method (RSM). The adsorption capacity of the MFA adsorbent for Zn2+, Pb2+and As(V) removal, calculated by the Langmuir model, was found to be 33.13, 26.06, and 29.71 mg g−1, respectively. The kinetic and thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. Due to their low desorption potential of the exhausted adsorbents, their effective reuse was established to be feasible. For this reason, the valorization of this material as an additive in construction materials was thereafter studied, where testing its toxicity leaching (TCLP) as well as the mechanical properties of construction material containing exhausted MFA confirmed its safe use. Hence, this study points to a possible “two-in-one” reuse of coal ash, initially as an adsorbent and later as an additive in a construction material.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Multisite Proton–Coupled Electron Transfer at a Keggin-Type Polyoxotungstate

Proton−coupled electron transfer (PCET) governs many redox transformations, but is thermodynamically constrained when proton and electron transfer occur at a single site. Here, we introduce a new multisite PCET (MSPCET) platform, based on the Keggin-type polyoxotungstate, [VW 12 O 40 ] 3− (VW 12 ). Pairing VW 12 with either Brønsted bases or acids yields reagent pairs with tunable effective bond dissociation free energies (BDFE eff ) over 15 kcal mol −1 , enabling both oxidative and reductive H atom transfer reactions. Kinetic studies on the oxidative pathway by using 2,4,6- t Bu 3 PhOH as a model hydrogen atom (H atom) donor reveal a product-like, entropy-dominated concerted proton−electron transfer (CPET) pathway from a preorganized hydrogen-bonded complex. By contrast, reductive H atom transfer reactions exhibit larger ΔH ‡ values, measurable kinetic isotope effects, and balanced Brønsted slope, consistent with synchronous CPET-type mechanism. Extension to N−H, O−H, and C−H substrates demonstrates the versatility of the VW 12 MS-PCET platform for tunable (de)hydrogenation.

Charge transfer↗
DOE OSTI2016

Effect of reaction atmosphere on structural and optical properties of hexagonal molybdenum oxide (h-MoO{sub 3})

The present work aims to synthesize single phase h-MoO{sub 3} nanocrytals by chemical precipitation method exposed under different reaction atmospheres. The reaction atmosphere have been successfully tuned as air, nitrogen and argon and studied its effects on structural, functional, morphology and optical properties by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and diffuse reflectance spectroscopy (DRS) measurements. The XRD result indicates that the sample exhibits characteristic hexagonal phase of MoO{sub 3}. The crystallite size is estimated by well known Scherrer’s method. The crystallite size is relative small in the case of sample prepared at argon atmosphere. The functional groups such as Mo-O, N-H and O-H are identified from FT-IR spectroscopy. The particle exhibits rod like morphology with perfect hexagonal cross-section. The optical absorption observed at 420-450 nm corresponds to fundamental optical absorption by h-MoO{sub 3}. The band gap values are estimated using Kublka-Munk (K-M) function and found to be 2. 87 eV, 2.93 eV and 2.97 eV for samples synthesized under air, nitrogen and argon, respectively.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Simulations for x-ray imaging of wave-packet dynamics

Previous work on imaging wave-packet dynamics with x-ray scattering revealed that the scattering patterns deviate substantially from the notion of instantaneous momentum density of the wave packet. Here we show that scattering patterns can provide clear insights into the electron wave-packet dynamics if the final state of the scattered electron and the scattered photon momentum are determined simultaneously. The scattering probability is shown to be proportional to the modulus square of the Fourier transform of the instantaneous electronic spatial wave function weighted by the final state of the electron. Several cases for the choice of final state of the electron are explored. First, the case where the final state can be measured up to a given principal quantum number n and orbital angular momentum l are presented. Next, the case where the final states can only be determined up to a given energy is discussed. Lastly, the case of an initial wave packet consisting of a large amount of a known stationary state and a small amount of an unknown stationary state is examined. The scattering profile is used to determine the properties of the unknown state in the wave packet.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1980

Performance of a flight qualified, thermoelectrically temperature controlled QCM sensor with power supply, thermal controller and signal processor

A thermoelectrically temperature controlled quartz crystal microbalance (QCM) system was developed for the measurement of ion thrustor generated mercury contamination on spacecraft. Meaningful flux rate measurements dictated an accurately held sensing crystal temperature despite spacecraft surface temperature variations from -35 C to +60 C over the flight temperature range. An electronic control unit was developed with magentic amplifier transformer secondary power supply, thermal control electronics, crystal temperature analog conditioning and a multiplexed 16 bit frequency encoder.

Wallace, D. A.↗
DOE OSTI2018

Kinetic, Isotherm and Thermodynamic Studies for Removal of Methylene Blue Using β-Cyclodextrin/Activated Carbon Aerogels

A novel aerogel (β-CD/AC) was prepared through polymerization reaction of β-cyclodextrin (β-CD) with activated carbon (AC) and vacuum freeze drying method. The structure and morphology of β-CD/AC were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) method and thermogravimetric analysis (TGA). β-CD/AC is used to deal with wastewater containing methylene blue (MB) dye. The effects of AC content in β-CD/AC, pH value, temperature, contact time and amount of adsorbent on the adsorption of MB were studied in detail. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The Langmuir monolayer adsorption capacity of MB onto β-CD/AC was estimated as 166.67 mg/g. The kinetics of MB onto β-CD/AC was well described by the pseudo-second order model. The thermodynamic parameters indicated that the adsorption reaction of MB onto β-CD/AC was endothermic and spontaneous.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Nonlinear shearing modes approach to the diocotron instability of a planar electron strip

The nonlinear evolution of the diocotron instability of a planar electron strip is investigated analytically by means of the nonlinear shearing mode for the solution of the initial and boundary value problems. The method is based on the sheared spatial coordinates which account for the motion of electron flow in the electrostatic field of the unstable diocotron modes in addition to the unperturbed sheared motion of the electron flow on the transformed shear coordinates. The time evolutions are studied by the solution of the initial and boundary value problems. The obtained solutions for the perturbed electrostatic potential include two nonlinear effects—the effect of the distortion of the boundaries of the planar electron strip and the effect of the coupling of the sheared nonmodal diocotron modes. It was proved by a two-dimensional particle-in-cell simulation that the developed theory is valid as long as the distortion of the boundaries of the basic shear flow does not change the frequency and growth rate of the linear diocotron instability in the transformed coordinates.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Energy conversion and transfer for plasmas in a magnetic expansion configuration

A two-dimensional axisymmetric particle-in-cell code with Monte Carlo collision conditions has been used to study particle energy transfer in plasmas and conversion in applied magnetic and electric fields appropriate to coaxial acceleration. The research incorporates a computation scheme with: a model of single particle magnetic interactions; a model of single particle interactions in electric and magnetic fields; and a model of multi-particle collisional interactions in order to understand the energy transfer processes and conversion mechanisms of charged plasma particles. This approach predicts electron and ion motions along with their energy variations for physical conditions that occur in the related models; the results allow comparison with experimental data for magnetic field strengths of 0.01–0.05 T and electrode voltages of 22.0–32.0 V. With the incorporation of magnetic and electric field effects on charged particles, the multi-particle model includes electron-neutral ionization collisions, ion-neutral charge exchange collisions, and electron-ion Coulomb collisions. This research presents a new approach to achieve an underlying understanding of the plasma energy transfer and conversion in the external electric and magnetic fields that is not possible using magnetohydrodynamics continuum representations. Results indicate the following innovative conclusions: (1) Radial and azimuthal energies of magnetized electrons are converted into an axial electron energy component in the diverging magnetic field, and the azimuthal kinetic energy of unmagnetized ions is converted into axial and radial components. (2) In electric and magnetic fields, electric field energy is primarily converted into axial kinetic energy of magnetized electrons by the energy transformation effects of magnetic fields, and for unmagnetized ions, the radial kinetic energy component dominates in the conversion of electric field energy. (3) For the collisional plasma, electron kinetic energy tends to increase (or decrease) to a terminal value since electrons lose energy in collisions then gain energy again from the field. Ions acquire most energy directly from the electric field, although part of the electric field energy arrives to the ions by collisions. Further, the ion axial energy component dominates the total ion energy. The collision processes are found to be integral and essential for the conversion of the plasma non-directed energy gain to be converted into the resultant axial energy, the magnitudes of which are found to be in agreement with experimental results.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Structural transformation in nickel doped zinc oxide nanostructures

Graphical abstract: Display Omitted Highlights: ► A systematic study of 1–10% Ni doped ZnO nanostructures (Ni:ZnO NS). ► Effect of Ni concentration on properties of Ni:ZnO NS was intensively investigated. ► Structural transformation in Ni:ZnO NS demonstrated through characterizations. ► Alteration in vibrational modes of Ni:ZnO NS were meticulously analyzed. ► Intricacies of structural evolution, from particles to rods, were comprehended. -- Abstract: In this article, structural transformation in nickel doped zinc oxide nanostructures is reported. The ZnO nanostructures are synthesized with 1–10% of nickel doping through a chemical precipitation method. The undoped and doped nanostructures were systematically investigated employing X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM/SEM), Fourier transform infrared (FTIR) and micro-Raman spectroscopy (μRS). The wurtzite phase of the material and associated lattice parameters were ascertained through XRD analysis. TEM/SEM images reveal the structural transformation of ZnO nanostructures with variation in nickel doping. The study of vibrational modes of nanostructures at different stages of structural transformation, as performed through FTIR and Raman spectroscopy, assist in deciphering the pivotal role of doping concentration in gradual evolution of nickel doped ZnO structure from nanoparticles to nanorods.

36 MATERIALS SCIENCE↗