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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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

In Vitro and In Silico Studies of Chitin and Chitosan Based Nanocarriers for Curcumin and Insulin Delivery

The evaluation of drug delivery potential, molecular interactions of the polymeric nanoparticles with the drug molecule and release kinetics encounters more time consumption and also cost. In this study, we have adopted the combination of in vitro and in silico approaches to evaluate the drug delivery property of the polymeric nanoparticles viz. chitin and chitosan. Herein, two different therapeutic agents such as curcumin (a hydrophobic drug) and insulin (a therapeutic protein) were used to study the delivery potential of chitin and chitosan nanoparticles. The drug loaded chitin and chitosan nanoparticles were prepared and characterized using Fourier transform infra red spectroscopy, X-ray diffraction, dynamic light scattering and scanning electron microscopy analysis. In the in vitro drug delivery experiments, chitosan nanoparticles exhibited better encapsulation efficiency, drug loading capacity and prolonged release of the drug molecules than that of the chitin nanoparticles to both curcumin and insulin. Meanwhile the in silico experiments such as molecular docking and molecular dynamics predicted the molecular interactions and binding energy involved between the nanoparticles and the drug molecules. From this study, we suggest that the chitosan nanoparticles could be used as a carrier molecule for both curcumin and insulin. Graphical Abstract: .

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Cetyltrimethylammonium Bromide (CTAB) Surfactant-Assisted Synthesis of BiFeO{sub 3} Nanoparticles by Sol-Gel Auto-Combustion Method

In this research, BiFeO{sub 3} nanoparticles were synthesized by sol-gel auto-combustion method with and without the addition of cetyltrimethylammonium bromide (CTAB) surfactant. The effect of different amounts of CTAB addition (0, 1.5, 3, and 6 wt.%) on phase constituents, microstructure, and magnetic properties of the synthesized samples were evaluated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and vibration sample magnetometer (VSM). Also, BiFeO{sub 3} nanoparticles were used for the degradation of methylene blue (MB) as a typical dye pollutant under UV irradiation. XRD results showed the formation of BiFeO{sub 3} mainly with some minute impurity phases such as Bi{sub 2}O{sub 3} and γ-Fe{sub 2}O{sub 3}. Proper amounts of CTAB addition (1.5 wt.%) considerably eliminates Bi{sub 2}O{sub 3} and γ-Fe{sub 2}O{sub 3} residuals in the combustion product. FESEM micrographs show particle size reduction and also more uniform particle size distribution when using 0.75 wt.% of CTAB addition. In the presence of the BiFeO{sub 3}, the UV irradiation for 120 min resulted in 26% degradation of MB, in a sample with 0.75 wt.% CTAB. The synthesized nanoparticles of BiFeO{sub 3} in the sample with 0.75 wt.% CTAB after calcination at 650 {sup ∘}C showed a weak ferromagnetism behavior with saturation magnetization of 0.54 emu/g. {sub i}H{sub C} values of the samples are in the range of 200 to 238 Oe, depending on the crystallite size and phase constituents of the samples.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Effects of Bi{sup 3+} Substitution on Structural, Morphological, and Magnetic Properties of Cobalt Ferrite Nanoparticles

In this research, the structural, morphological, and magnetic properties of Bi-doped cobalt ferrite (CoFe{sub 2-x}Bi{sub x}O{sub 4}) nanoparticles with x = 0.0, 0.05, 1, 0.15, and 0.2, prepared by the sol-gel method, were studied. In order to characterize the samples, several equipment and analyses including thermo-gravimetric and differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared spectrometer (FT-IR), and vibrating sample magnetometer (VSM) were used. The average crystallite sizes of the prepared CoFe{sub 2-x}Bi{sub x}O{sub 4} were calculated using the Scherer, UDM, SSP, and Halder-Wagner methods. The average crystallite sizes for the samples were found in the range of 26 to 44 nm, which can be attributed to the grain growth of the particles. FT-IR spectrum showed bands in the range of 430 to 590 cm{sup −1} due to the stretching vibration of an oxygen atom and metal ions (Fe-O), confirming the formation of spinel ferrite. Surface morphology of the samples was studied using FESEM. The VSM results showed that the saturation and remanence magnetizations increased by raising the doping values up to x = 0.1. The Curie temperature of the cobalt nanoferrites was determined using Faraday’s technique. The highest Curie temperature was found to be 580 °C for the undoped sample.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2015

Growth mechanism and magnetic and electrochemical properties of Na{sub 0.44}MnO{sub 2} nanorods as cathode material for Na-ion batteries

Nanorods of Na{sub 0.44}MnO{sub 2} are a promising cathode material for Na-ion batteries due to their large surface area and single crystalline structure. We report the growth mechanism of Na{sub 0.44}MnO{sub 2} nanorods via solid state synthesis and their physical properties. The structure and the morphology of the Na{sub 0.44}MnO{sub 2} nanorods are investigated by X-ray diffraction (XRD), scanning and tunneling electron microscopy (SEM and TEM), and energy-dispersive X-ray (EDX) techniques. The growth mechanism of the rods is investigated and the effects of vapor pressure and partial melting of Na-rich regions are discussed. The magnetic measurements show an antiferromagnetic phase transition at 25 K and the μ{sub eff} is determined as 3.41 and 3.24 μ{sub B} from the χ–T curve and theoretical calculation, respectively. The electronic configuration and spin state of Mn{sup 3+} and Mn{sup 4+} are discussed in detail. The electrochemical properties of the cell fabricated using the nanorods are investigated and the peaks in the voltammogram are attributed to the diffusion of Na ions from different sites. Na intercalation process is explained by one and two Margules and van Laar models. - Highlights: • We synthesized Na{sub 0.44}MnO{sub 2} nanorods via a simple solid state reaction technique. • Our studies show that excess Na plays a crucial role in the nanorod formation. • Magnetization measurements show that Mn{sup 3+} ions are in LS and HS states. • The electrochemical properties of the cell fabricated using the nanorods are investigated. • Na intercalation process is explained by one and two Margules and van Laar models.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

The role of titanium and vanadium based precipitates on hydrogen induced degradation of ferritic materials

Highlights: • Hydrogen induced damage is studied in Fe-C-Ti and Fe-C-V ferritic alloys. • Fe-C-Ti is less susceptible to hydrogen embrittlement than Fe-C-V. • Fe-C-V is less susceptible to blistering than Fe-C-Ti. • The role of diffusible hydrogen depends on the damage mechanism. - Abstract: The hydrogen induced damage of generic Fe-C-Ti and Fe-C-V ferritic alloys was investigated to assess the influence of precipitates on the hydrogen sensitivity of a material. The precipitates, formed during heat treatment, were evaluated by scanning transmission electron microscopy (STEM). The hydrogen/material interaction was evaluated by: 1) melt and hot extraction to determine the total and diffusible hydrogen content, respectively, 2) permeation experiments to calculate the diffusion coefficient, 3) thermal desorption spectroscopy to determine the hydrogen trapping characteristics of the materials. Furthermore, two different types of hydrogen induced damage were evaluated, i.e. hydrogen assisted cracking and blistering, resulting from electrochemical hydrogen charging with and without the application of an external load, respectively. Evaluation of the hydrogen induced damage and the role of the precipitates was performed by combining optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). An important though divertive role of diffusible hydrogen is observed in both damage mechanisms for the investigated microstructures. On the one hand, a large amount of diffusible hydrogen compared to strongly trapped hydrogen promotes hydrogen assisted cracking of materials, while on the other hand, the blistering phenomenon is delayed under such conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Kinetics of hydrogen adsorption on MgH{sub 2}/CNT composite

Highlights: • Hydrogen adsorption comparisons of commercial, milled, and MgH{sub 2} composite. • Hydrogen adsorption capacity and kinetics improves tremendously by CNT embedding. • Unsteady state modeling and simulation of adsorption kinetics. - Abstract: Magnesium hydride (MgH{sub 2})–carbon nanotubes (CNT) composite has been prepared by high-energy ball milling method and their experimental and kinetic hydrogen adsorption studies was assessed. Hydrogen adsorption studies were performed by Sievert’s volumetric apparatus and kinetic evaluation was conducted by surface chemistry and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type mode. Powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were performed. Hydrogen adsorption capacity of commercial MgH{sub 2}, milled MgH{sub 2}, and MgH{sub 2}/CNT composite are found to be 0.04, 0.057, and 0.059 g (H{sub 2})/g (MgH{sub 2}) at 673 K and hydrogen pressure of 4.6 MPa. Addition of 5 wt% of CNTs to MgH{sub 2} proved to be very critical to enhance hydrogen adsorption as well as to improve its kinetics. It was observed that hydrogen adsorption is not in quasi-state equilibrium and is modeled using kinetic rate laws.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microwave-assisted synthesis of well-shaped UiO-66-NH2 with high CO2 adsorption capacity

Highlights: • Well-shaped UiO-66-NH{sub 2} was prepared through microwave heating in a short time. • Addition of HAc improves crystallinity and CO{sub 2} adsorption capacity of the UiO-66-NH{sub 2}. • UiO-66-NH{sub 2} prepared by microwave heating shows a higher CO{sub 2}/N{sub 2} adsorption selectivity. - Abstract: In a detailed study, the influence of microwave irradiation, synthesis time and temperature, addition of acetic acid (HAc) as a modulator on the morphology, crystallinity and stability of UiO-66-NH{sub 2} is investigated to develop a reliable and reproducible strategy for the preparation of well-shaped UiO-66-NH{sub 2}. The UiO-66-NH{sub 2} were characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and gas adsorption. It is found that well-shaped UiO-66-NH{sub 2} with a high CO{sub 2} adsorption capacity can be synthesized in a short time by microwave heating. The UiO-66-NH{sub 2} crystals synthesized by microwave heating are of high quality and show a superior CO{sub 2} adsorption capacity (5.8 mmol/g at 273k and 1 bar) due to the strong interactions between the −NH{sub 2} group and CO{sub 2}. The CO{sub 2}/N{sub 2} selectivity of the obtained UiO-66-NH{sub 2} at 298 K and 1 bar is 66, which is much higher than that of the pristine UiO-66 of 17.8.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Synthesis and visible light photocatalytic properties of iron oxide–silver orthophosphate composites

The iron oxide-silver orthophosphate composites were successfully synthesized by co-precipitation method using Fe(NO{sub 3}){sub 3}.9H{sub 2}O, AgNO{sub 3}, and Na{sub 2}HPO{sub 4}.12 H{sub 2}O, followed by calcination at 500°C for 5 hours. The Fe/Ag mole ratios of iron oxide-silver orthophosphate composites were designed at 0, 0.1, 0.2, 0.3 and 0.4. The samples were characterized using X-ray Diffraction, Diffuse Reflectance Spectroscopy, Scanning Electron Microscopy and Specific Surface Area. The photocatalytic activities were evaluated using Rhodamine B degradation under visible light irradiation. The iron oxide-silver orthophosphate composite with the Fe/Ag mole ratio of 0.2 exhibited higher photocatalytic activity compared to the pure Ag{sub 3}PO{sub 4} under visible light irradiation. The enhanced photocatalytic activity could be attributed to the effective separation of hole (+) and electron pairs in the iron oxide-silver orthophosphate composite.

36 MATERIALS SCIENCE↗
DOE OSTI2016

On a reduction in cracking upon the growth of AlN on Si substrates by hydride vapor-phase epitaxy

The main problem of the epitaxial growth of thick AlN layers on a Si substrate consists in the formation of cracks, which complicates the application of structures of this kind in the fabrication of semiconductor devices. The possibility of obtaining crack-free AlN layers with a thickness exceeding 1 μm and a mirror- smooth surface by hydride vapor-phase epitaxy is demonstrated. The properties of the layers are studied by X-diffraction analysis, optical and scanning electron microscopy, and Raman spectroscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Pushing the limits of electron ptychography

Here, ptychographic imaging in transmission electron microscopy is based on the detection of a huge number of diffraction patterns generated as an electron-beam probe scans the sample. Unlike conventional diffraction experiments where information about the phase of the scattered beam is lost, by scanning the entire sample and recording the diffraction patterns, an inversion analysis can reconstruct the complex amplitude of the beam and ultimately the atomic positions. Probe beams continue to decrease in size and can be much smaller than the distance between scatterers. The diffraction spots also broaden and interfere with one another (see the figure). Analysis of this interference allows more information to be extracted, such as minute details of nuclei position and electronic structure that define physical properties and enable visualization of subtle details of electric fields, orbital orderings, ferroic behavior, and perhaps local spins. Ptychography and related techniques are poised to revolutionize the field of electron microscopy, in much the same way as they have in x-ray crystallography (1), and as aberration correction has achieved for imaging, provided that some key challenges can be met.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Effect of Varying Filler Concentration on Zinc Oxide Nanoparticle Embedded Chitosan Films as Potential Food Packaging Material

Prevailing scenario of non-biodegradable food packaging materials worldwide was the motivation for this research. More than half of the packaging materials used today are non-biodegradable and lack one or the other feature that keeps it from being an ideal food packaging material. Based on the current need of food grade packaging materials, the present study illustrates the amelioration of the properties of biodegradable chitosan films with the incorporation of zinc oxide (ZnO) nanoparticles in varying concentration. The ZnO nanoparticles (ZnONPs) used as fillers in the chitosan films were synthesized by supersaturation method. They were characterized using UV–visible spectrophotometry, X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The particles were observed to be around 100–200 nm in size. The chitosan films with varying concentration of ZnONPs were synthesized and characterized using Fourier transform infrared spectroscopy and FE-SEM. The films were studied for their thermal stability, water vapor transmission rate (WVTR) and mechanical properties. The thermal stability, as determined by Thermo Gravimetric Analysis and Differential Scanning Calorimetry increased slightly with increasing percentage of embedded ZnONPs while a substantial decrease in WVTR was observed. Mechanical properties also showed improvements with 77% increment in tensile modulus and 67% increment in tensile strength. The antimicrobial activity of the films was also studied on gram positive bacterium Bacillus subtilis (B. subtilis) and gram negative bacterium Escherichia coli (E. coli) by serial dilution method. A twofold and 1.5-fold increment in the antimicrobial activity was observed for B. subtilis and E. coli, respectively, with increased ZnONPs concentration in the films from 0(w/w) to 2%(w/w). Films thus prepared can prove to be of immense potential in the near future for antimicrobial food packaging applications.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Investigation and characterization of ZnO single crystal microtubes

Morphological, structural, and optical characterization of microwave synthesized ZnO single crystal microtubes were investigated in this work. The structure and morphology of the ZnO microtubes are characterized using X-ray diffraction (XRD), single crystal diffraction (SCD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The results reveal that the as-synthesized ZnO microtube has a highly regular hexagonal cross section and smooth surfaces with an average length of 650–700 μm, an average outer diameter of 50 μm and wall thickness of 1–3 μm, possessing a single crystal wurtzite hexagonal structure. Optical properties of ZnO single crystal microtubes were investigated by photoluminescence (PL) and ultraviolet-visible (UV-vis) absorption techniques. Room-temperature PL spectrum of the microtube reveal a strong UV emission peak at around 375.89 nm and broad and a weak visible emission with a main peak identified at 577 nm, which was assigned to the nearest band-edge emission and the deep-level emission, respectively. The band gap energy of ZnO microtube was found to be 3.27 eV. - Highlights: • ZnO microtube length of 650–700 μm, diameter of 50 μm, wall thickness of 1–3 μm • ZnO microtube possesses a single crystal wurtzite hexagonal structure. • The crystal system is hexahedral oriented along a-axis with indices of (100). • A strong and sharp UV emission at 375.89 nm (3.29 eV) • One prominent absorption band around 378.88 nm (3.27 eV)

36 MATERIALS SCIENCE↗
DOE OSTI2015

Morphology dependent catalytic activity of TiO{sub 2} nanostructures towards photodegradation of Rose Bengal

This work deals with the synthesis of TiO{sub 2} nanostructures using sol-gel and hydrothermal method for evaluating their photodegradation performance towards decolorization of Rose Bengal (RB). A combination of characterization techniques including X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and UV–Vis spectroscopy were utilized to evaluate the structural, morphological and optical properties of the obtained nanostructures. It was observed that the TiO{sub 2} nanoparticles prepared using hydrothermal method were highly crystalline and possess higher band gap value, even when same conditions of temperature, pressure, precursor ratios and solvent amount was kept constant while synthesizing TiO{sub 2} nanostructures via sol-gel method. The obvious effect of porous morphology exhibited by TiO{sub 2} nanoparticles prepared using hydrothermal route is reflected in its decolorization performance whereby 92.5% of the RB dye solution was degraded in 70 min of irradiation time.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Preference of multi-walled carbon nanotube (MWCNT) to single-walled carbon nanotube (SWCNT) and activated carbon for preparing silica nanohybrid pickering emulsion for chemical enhanced oil recovery (C-EOR)

The aim of this research was to determine the best nano hybrid that can be used as a Pickering emulsion Chemical Enhanced Oil Recovery (C-EOR). Therefore, we have prepared different carbon structures nano hybrids with SiO{sub 2} nano particles with different weight percent using sol-gel method. The as-prepared nano materials were characterized with X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and Thermal Gravimetric Analysis (TGA). Pickering emulsions of these nanohybrids were prepared at pH=7 in ambient temperature and with distilled water. Stability of the mentioned Pickering emulsions was controlled for one month. Emulsion phase morphology was investigated using optical microscopic imaging. Evaluation results demonstrated that the best sample is the 70% MWCNT/SiO{sub 2} nanohybrid. Stability of the selected nanohybrid (70% MWCNT/SiO{sub 2} nanohybrid) was investigated by alteration of salinity, pH and temperature. Results showed that the mentioned Pickering emulsion has very good stability at 0.1%, 1% salinity, moderate and high temperature (25 °C and 90 °C) and neutral and alkaline pH (7, 10) that is suitable for the oil reservoirs conditions. The effect of the related nano fluid on the wettability of carbonate rock was investigated by measuring the contact angle and interfacial tension. Results show that the nanofluid could significantly change the wettability of the carbonate rock from oil wet to water wet and can decrease the interfacial tension. Therefore, the 70% MWCNT/SiO{sub 2} nanohybrid Pickering emulsion can be used for Chemical Enhanced Oil Recovery (C-EOR).

36 MATERIALS SCIENCE↗
DOE OSTI2016

Structural, optical and photo-catalytic activity of nanocrystalline NiO thin films

Highlights: • Synthesis of nanocrystalline NiO thin films with different thicknesses using DC magnetron sputtering technique. • Effect of film thickness and particle size on photo-catalytic degradation of methyl green dye under UV light was studied. • The deposited NiO thin films are efficient, stable and possess high photo-catalytic activity upon reuse. - Abstract: Physical deposition of nanocrystalline nickel oxide (NiO) thin films with different thickness 30, 50 and 80 nm have been done on glass substrate by DC magnetron sputtering technique and varying the deposition time from 600, 900 to 1200 s. The results of surface morphology and optical characterization of these films obtained using different characterization techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), photoluminescence (PL) and UV–vis spectrophotometry provide important information like formation of distinct nanostructures in different films and its effect on their optical band gap which has decreased from 3.74 to 3.37 eV as the film thickness increases. Most importantly these films have shown very high stability and a specialty to be recycled without much loss of their photo-catalytic activity, when tested as photo-catalysts for the degradation of methyl green dye (MG) from the wastewater under the exposure of 18 W energy of UV lamp.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Effect of bath temperature on surface morphology and photocatalytic activity of ZnO nanorods

ZnO nanorods were prepared by using simple hydrothermal method using four different bath temperatures. All the prepared ZnO nanorods are annealed at 450°C and are characterized by using various techniques such as X-ray diffraction, UV spectra and scanning electron microscopy. Photocatalytic activity of the prepared ZnO nanorods is analyzed. A novel photocatalytic reactor designed with ZnO nanorods prepared at 90°C shows enhanced catalytic efficiency. The role of light irradiation time, bath temperature and surface morphology of the ZnO nanorods on the performance of photocatalytic reaction is analyzed.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

A comprehensive investigation on the properties of nanostructured cerium oxide

The structural, optical, magnetic and electrical properties of cerium oxide (CeO{sub 2}) nanoparticles prepared by hydrothermal route are analyzed by subjecting them to characterization techniques such as Powder X-ray diffraction (PXRD), High resolution scanning electron microscope (HRSEM), High resolution transmission electron microscope (HRTEM), Energy Dispersive X-ray Analysis (EDAX), Fourier transform infra red spectroscopy (FTIR), Raman spectroscopy, Ultraviolet–Visible analysis, Vibrating sample magnetometer (VSM) analysis and Dielectric measurements. The PXRD, FTIR, Raman and EDAX analyses confirm the formation of CeO{sub 2} nanoparticles. The PXRD studies reveal that the cerium oxide nanoparticles have crystalline nature and have Face Centered Cubic structure. The average crystallite size, estimated using Scherrer formula, is 7 nm. The HRSEM and HRTEM images reveal that the CeO{sub 2} nanoparticles have spherical morphology with an average particle size of 23 nm. The optical band gap energy of the cerium oxide nanoparticles, calculated from UV–Vis studies, is 3.4 eV which could be due to the substantial concentration of Ce{sup 3+} ions in the ceria nanoparticles. The Ferromagnetic behavior of CeO{sub 2} at room temperature is implied from VSM studies. The Dielectric analysis divulge that the dielectric constant of cerium oxide nanoparticles decreases as the frequency and temperature increases. The electrical behaviour, activation energy and relaxation time of electrons of CeO{sub 2} nanoparticles are studied by plotting Nyquist plot, Arrhenius plot and Bode plot respectively.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Dynamic Hosts for High-Performance Li–S Batteries Studied by Cryogenic Transmission Electron Microscopy and in Situ X-ray Diffraction

Developing a high-performance sulfur host is central to the commercialization and general development of lithium–sulfur batteries. Here, for the first time, we propose the concept of dynamic hosts for lithium–sulfur batteries and elucidate the mechanism through which TiS 2 acts in such a fashion, using in situ X-ray diffraction and cryogenic scanning transmission electron microscopy (cryo-STEM). A TiS 2 –S composite electrode delivered a reversible capacity of 1120 mAh g –1 at 0.3 C after 200 cycles with a capacity retention of 97.0% and capacities of 886 and 613 mAh g –1 at 1.0 C up to 200 and 1000 cycles, respectively. Finally, our results indicate that it is Li x TiS 2 (0 < x ≤ 1), rather than TiS 2 , that effectively traps polysulfides and catalytically decomposes Li 2 S.

25 ENERGY STORAGE↗