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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Micro Crystalline Bamboo Cellulose Based Seaweed Biodegradable Composite Films for Sustainable Packaging Material

This study is aimed to fabricate and characterize the seaweed- biodegradable films incorporated with varying concentrations of microcrystalline cellulose (MCC) which was extracted from two bamboo sources: Schizostachyum brachycladum (BLMCC) and Gigantochloa scortechinii (BSMCC). Pure biodegradable seaweed film was directly fabricated from red seaweed (Kappaphycus alvarezii). In this demonstrated work, commercial MCC (CMCC), BLMCC and BSMCC were used to reinforce the pure seaweed bio-degradable film at different loading concentrations (0, 1, 3, 5, 7, 10 and 15%) based on the dried-weight of seaweed, for packaging applications. There was substantial improvement in the tensile strength and contact angle values while reduction in the water vapor permeability and elongation at break values with the incorporation of the CMCC, BLMCC and BSMCC into the seaweed pure film matrix, which is highly desirable for the packaging material in the current scenario. The morphology of the fabricated films confirmed that there was good dispersion of the 7% of CMCC, 5% of BLMCC and 3% of BSMCC in the pure seaweed films, which resulted in the enhanced mechanical properties. So far, this is the first report on the microcrystalline cellulose based seaweed films with excellent mechanical properties, which makes them suitable for packaging application. The demonstrated work proved that both BSMCC and BLMCC based seaweed composite films have the huge potential to be used as biodegradable packaging material for wide range of applications. Graphical Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

A Novel Rigid PU Foam Based on Modified Used Palm Oil as Sound Absorbing Material

Novel bio-polyol was successfully synthesized from used palm oil (UPO) and was further tested for preparing rigid polyurethane (PU) foams. In this work, the modified used palm oil (MUPO) was synthesized in a single step process, by epoxidation together with ring opening reactions. The reagent ratios and reaction time for MUPO synthesis were also studied. The chemical structure of MUPO was confirmed by {sup 1}H-NMR spectroscopy and FTIR. The hydroxyl value of MUPO increased with reaction time and depended also on reagent ratio. The GPC trace of MUPO showed a bimodal distribution and the molecular weight slightly decreased with OH value. New rigid PU foams were prepared from MUPO. The foam cell size and compressive strength at 10% strain increased with OH value. All the rigid PU foams had excellent sound absorption coefficients. The lowest OH value (OHV = 100 mg KOH/g) provided sound absorption from 2200 Hz. In addition, the flammability of PU foams was improved by adding 30% wt of triphosphate (TPP) as flame retardant. The investigations showed that a bio-polyol based on UPO was suitable for preparing rigid PU foams that could serve as alternative sound absorbing materials. Graphical Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Antifungal Activity of Polyhexamethyleneguanidine Derivatives Introduced into Biodegradable Polymers

Experiments were conducted to investigate the antifungal activities of polyhexamethyleneguanidine (PHMG) derivatives introduced into polylactide (PLA), polyhydroxybutyrate (PHB) and polycaprolactone (PCL) against Aspergillus niger, Penicillium chrysogenum and Candida albicans. All of the PHMG derivatives inhibited the germination of A. niger and P. chrysogenum. All of the derivatives exerted a much stronger inhibitory effect on the cells of C. albicans. PHMG granular polyethylene wax (at the concentration of 1.0%) has a fungicidal effect. The reduction in the number of yeast cells capable of growing on the surface composites PLA, PHB and PCL with PHMG granular polyethylene wax for 24 h was R > 2. PHMG derivatives introduced into PLA decreased hydrolases activity in A. niger and P. chrysogenum. All of the PHMG derivatives introduced into all investigated polymers inhibited the hydrolases activity in C. albicans proportionately to concentration. PHMG granular polyethylene wax at a concentration of 1.0% most strongly inhibited hydrolases activity in yeast. The composites produced from PLA, PHB, PCL and this PHMG derivatives can be used in many areas to reduce the growth of yeast. The studied composites can potentially be used for the production of biomedical or packaging materials. Graphical Abstract: PHMG derivates introduced into polymer have slightly biocidal properties against molds and strong against yeast. The composites produced from PLA, PHB, PCL and this PHMG derivatives can be used in the many areas to reduce the growth of yeast. The studied composites can potentially be used for the production of biomedical or packing materials. .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Enhanced Mechanical and Barrier Performance of Poly (Lactic Acid) Based Nanocomposites Using Surface Acetylated Starch Nanocrystals

Poly (lactic) acid (PLA) based nanocomposites reinforced with starch nanocrystals (SNC) extracted from high amylopectin waxy maize starch and acetylated starch nanocrystals (Ac-SNC), were prepared and their influence on the overall properties of PLA nanocomposites were studied. The two nanofillers (SNC and Ac-SNC) were incorporated in PLA at two different loadings (1 and 3 wt%) by solvent casting and evaporation technique. Surface acetylation of SNC was confirmed by Fourier Transform infra-red spectroscopy and nuclear magnetic resonance spectroscopy and the crystalline structure by X-ray diffraction. This paper reports the influence of incorporating unacetylated and surface acetylated starch nanocrystals on morphological, barrier, mechanical, and rheological properties of PLA based nanocomposites. While both nanofillers improved the properties of PLA, the PLA-Ac-SNC had superior properties to that of PLA-SNC nanocomposites, due to better filler dispersion and interaction with the polymer matrix. These sustainable nanocomposites with improved properties will expand the application of these bio-sourced starch nanocrystals. Graphical Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Waste Eggshells for the Decoration of Carbon Nanotubes and Graphene Nanosheets with Hydroxyapatite for Preparation of LLDPE Nanocomposites

Waste eggshells were used to decorate functionalized carbon nanotubes (CNT) and graphene oxide (GO) by hydroxyapatite (HAP) using in situ synthesis. The HAP decorated CNT and GO were characterized by X-ray diffraction, SEM, and IR spectroscopic techniques. CNT-HAP and GO-HAP were further used to prepare polymer nanocomposites by addition of different percentages of synthesized CNT-HAP and GO-HAP as fillers into linear low density polyethylene (LLDPE). The prepared nanocomposites specimens were utilized for physical and thermo-mechanical analysis. Mechanical properties of the LLDPE nanocomposites were improved with increasing the percentage of CNT-HAP and GO-HAP fillers compared to the pristine LLDPE. Hardness of hybrid-CNT-HAP/LLDPE composite was increased as compared to the GO-HAP/LLDPE, where as tensile strength of the GO-HAP/LLDPE was higher than that of the CNT-HAP/LLDPE composite. Flammability of CNT-HAP and GO-HAP composites was decreased by 32% as compared to the pristine LLDPE. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Impact of Blend Proportion on the Miscibility and Thermal Characteristics of Synthetic Plastic-Derived Polypentapeptide with Commercially Available Polyvinyl Alcohol

Plastic-based polypeptides are versatile entities formed to conceive a broad range of scaffold biomaterials. They possess distinct, repetitive, hydrophobic sequences that confer conservation, reversibility, temperature-dependent self-association and dissociation properties. The repeating sequence of plastic-based peptides, poly(AVGVP) have been synthesized by the solution phase method and characterized by {sup 13}C and {sup 1}H-NMR spectroscopy. The intermolecular interactions between poly(AVGVP) and polyvinyl alcohol (PVA) was explored in solution and solid phase by diverse analytical methods. The interaction parameters, namely; α, β, µ and ∆[η]{sub m} obtained from the dilute solution viscometric approach, unveiled that the two polymers were miscible up to 40% of the polypeptide in the blends. Besides, Fourier transform infrared (FTIR) spectroscopy authenticated the formation of strong intermolecular hydrogen bonds connecting blend networks. Further, other analytical techniques such as DSC, SEM and XRD probes advocated the miscibility results. Thermogravimetric investigation of the blends confirmed the proportionate decrease of the thermal stability with the increase of polypentapeptide, attributable to the intermolecular amalgamation between the polypeptide and PVA. The blends and plain poly(AVGVP) degraded completely at about 700 °C, whereas the virgin PVA was about only 60% at this temperature. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of the Rheology Behavior of Water-Soluble Polyacrylamides and Their Efficiency of Flocculation

Organic polymers such as water-soluble polyacrylamides that are used as flocculants in solid–liquid separations, have their flocculation efficiency determined by the behavior of their macromolecules in solution. This behavior is affected by its intrinsic characteristics, especially the presence of ionic groups in its macromolecules. In this context, the present work aimed to characterize three water-soluble polyacrylamides. The effect of the intrinsic properties of each polymer on the behavior of the polymer chains in aqueous solution was compared in different environments. Beside this, the polymers behavior effect on the destabilization of particles was evaluated through kaolin particle aggregation studies. Viscosity results show that the conformation of the macromolecules in solution is altered according to the amount of ionized groups present. This variation, together with other factors such as the affinity with the kaolin particles and the excess of ions in solution, reflects in the flocculation efficiency of kaolin particles, in the flocs size and the flocs sedimentation rate. Graphic Abstract: .

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

Magnetic Nanoparticles Impregnated, Cross-Linked, Porous Chitosan Microspheres for Efficient Adsorption of Methylene Blue from Pharmaceutical Waste Water

The study demonstrates the preparation of MnFe{sub 2}O{sub 4} impregnated chitosan-microspheres (CMMS) as adsorbents for efficient removal of cationic thiazine dye, methylene blue. A facile approach with great economic and technical advantages to obtain highly crystalline manganese ferrite nanoparticles by solution combustion method is accounted. CMMS were characterized and evaluated for MB adsorption using linear forms of Freundlich and Langmuir adsorption isotherms, pseudo-first order, pseudo-second order and Elovich kinetic models. Application of CMMS to pharmaceutical waste, desorption of MB and reusability of CMMS are reported. Significantly, MB concentration in treated real sample was reduced by ~ 18 times to that of initial concentration. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Polyvinyl Alcohol (PVA)–Azadirachta indica (Neem) Nanofibrous Mat for Biomedical Application: Formation and Characterization

The present study provides credence to the formation of polyvinyl alcohol (PVA)–Azadirachta indica (neem) nanofibrous mat (PNNM) under optimum processing conditions of electrospinning technique from a mixer of PVA and neem extract to utilize the inherent medicinal properties of this herb for biomedical application. The bonding behavior, orientation of fibers, thermal behavior, and moisture management properties were evaluated by Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermo gravimetric analysis (TGA) and moisture management tester (MMT) reports respectively. The antibacterial activity of the developed sample at the maximum mixing ratio of neem extract (80%) was tested against Gram-positive (S. aureus) bacteria using agar disc diffusion method. The results reveal that the prepared nanofibrous mat exhibited better thermal and moisture management properties in comparison with PVA nanofiber alone. The formation of smooth fibers was confirmed by SEM images having average diameter of 185 nm under 5k, 10k and 15k magnifications. The characteristic peaks of PVA and neem constituents in FTIR spectra of the developed mat confirmed the presence of both components. Bacterial resistance was reached up to 20 mm due to the antibacterial constituents of neem extract. Thus the developed mat could be used as a biocompatible and bio based in biomedical applications. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2018

Rich Soliton Structures for the Kraenkel-Manna-Merle (KMM) System in Ferromagnetic Materials

A particular attention is paid to investigate the Kraenkel-Manna-Merle (KMM) system, which can describe the nonlinear short-wave propagation in saturated ferromagnetic materials with zero-conductivity in an external field. A class of exact soliton solutions is constructed via the generalized G{sup ′}/G-expansion method. Some novel soliton structures are excited by choosing the arbitrary functions in the solution as certain specific functions. Hump-soliton, cusp-soliton, loop-soliton, and kink-soliton are observed graphically. The results reveal the system theoretically possesses extremely rich soliton structures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Large Colloids in Cholesteric Liquid Crystals

We describe a coarse-grained Landau-de Gennes model of liquid crystals (LCs) including hydrodynamics based on the Beris–Edwards equations. The model is employed to study the impact of large colloids on the long range LC defect structure in the cholesteric LC blue phases. ‘Large’ here means that the particle size is comparable to the cholesteric pitch, the length scale on which the LC order undergoes a helical twist. We investigate the case of a single particle, with either normal or degenerate planar anchoring, placed initially in an equilibrium blue phase LC. It is found that in some cases, well defined steady disclination structure emerges at the particle surface, while in other cases no clear steady state is reached in the simulations, and disclination reorganisation appears to proliferate through the bulk LC. These systems are of potential interest in the context of using LCs to template self-assembly of colloid structure, e.g., for opto-electronic devices. Computationally, we demonstrate a parallel approach using mixed message-passing and threaded model on graphical processing units allows effective and efficient progress for this problem.

Physics↗
DOE OSTI2018

Energy of Motion of Internal and Surface Waves in a Two-Layer Hydrodynamic System

We study the energy of wave motion in a two-layer “layer with solid bottom–layer with free surface” hydrodynamic system. The dependences of the energies of motion of internal and surface waves on the geometric and physical parameters of the system are analyzed. The contribution of the second approximation to the total energy of the system is estimated. The reliability of the obtained results is verified. The results are graphically illustrated.

42 ENGINEERING↗
DOE OSTI2012

SDAT implementation for the analysis of radioxenon β–γ coincidence spectra

The Standard Deconvolution Analysis Tool (SDAT) was developed for analysis of radioxenon β-γ coincidence spectra measured as part of the International Monitoring System (IMS) as defined in the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The SDAT software analyzes each β-γ coincidence spectrum by fitting library vectors of each radionuclide of interest: 131mXe, 133mXe, 133Xe, and 135Xe. Detector background and radon are incorporated as optional components of the sample solution. Results are reported in mBq m-3. A new graphical user interface has been developed to facilitate ease of use and improve the data visualization. Automated energy vs. channel calibration algorithms were developed and implemented based on 137Cs β-γ coincidence spectra. Details on the user tool and testing are included.

Biegalski, S.↗
DOE OSTI2014

RadICalc. A program for estimating radiation intensity of radionuclide mixtures

RadICalc is a cross-platform program designed to calculate the intensity of radiation released by the decay of arbitrary isotopic mixtures. It was developed to address the need for a program that could calculate the composition, activity, and measurable radiation of a sample over time without significant effort from end-users. RadICalc uses Bateman's solutions for radioactive decay to determine activity over time. Radiation intensities are subsequently calculated using a database containing information about alpha particles, beta electrons, gamma- rays, conversion and Auger electrons, and X-rays. The user interface accepts input for isotopic mixture, initial number of atoms, and time passed since sample composition was known. Results are plotted graphically, and there is a search interface provided to and isotopes of interest. RadICalc can determine activity and radiation expected at specific masses with user-defined molecules in addition to atomic species; the latter is useful in mass based isotope separations for radiometric counting applications, a novel method under development at PNNL.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Optimal size of the block in block GMRES on GPUs: computational model and experiments

The block version of GMRES (BGMRES) is most advantageous over the single right hand side (RHS) counterpart when the cost of communication is high while the cost of floating point operations is not. This is the particular case on modern graphics processing units (GPUs), while it is generally not the case on traditional central processing units (CPUs). Here, in this paper, experiments on both GPUs and CPUs are shown that compare the performance of BGMRES against GMRES as the number of RHS increases, with a particular focus on GPU performance. The experiments indicate that there are many cases in which BGMRES is slower than GMRES on CPUs, but faster on GPUs. Furthermore, when varying the number of RHS on the GPU, there is an optimal number of RHS where BGMRES is clearly most advantageous over GMRES. A computational model for the GPU is developed using hardware specific parameters, providing insight towards how the qualitative behavior of BGMRES changes as the number of RHS increase, and this model also helps explain the phenomena observed in the experiments.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

New exact spatial and periodic-singular soliton solutions in nematic liquid crystal

The enterprising of nematicons has procured considerable recognition during the last few years due to its utilization in crystal technology. This research work contains some new exact traveling waves solutions in nematic liquid crystals. The modified simple equation method is employed to extract new traveling wave solutions. Two types of nonlinear mediums are investigated in this paper. New singular, periodic-singular and spatial solitons in liquid crystal are obtained by using analytical approach. The constraints fall out as the byproduct that guarantee their existence. The solutions are also highlighted graphically. This paper is leading to explore some unaccustomed results into this area of research.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Prepared σ-MnO{sub 2} thin films by chemical bath deposition methods and study of its optical and microstructure properties

In this work, σ-MnO{sub 2} thin films deposited by chemical bath deposition method at three concentration of solution. The influence of concentration on thickness, micromorphology and optical parameters were investigated by XRD, SEM, UV–Vis spectrophotometer, atomic force microscopic and multifractal analyses. The optical band gap of thin films is decreased with increase in concentration. The optical parameters: refractive index and real part of dielectric constant are increased with increase in concentration, but decrease in extinction coefficient and imaginary parts of dielectric constant are observed. The micromorphology and roughness of layers surface are changed as function of concentration. The studied samples have multifractal properties and can be included in computer algorithms useful for graphical representation of 3-D microtexture surfaces of σ-MnO{sub 2} thin films.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of fluorine doped CdO thin films by an simplified spray pyrolysis technique using nebulizer

The Cadmium oxide (CdO) and Fluorine (F) doped CdO thin films were effectively synthesized on glass substrates for different F doping concentrations (2, 4, 6, 8 at.%) using nebulized spray pyrolysis technique. The XRD analysis showed that all the films were polycrystalline having cubic structure with (111) preferential orientation. It was seen from the SEM photographs that the doping causes remarkable changes in the surface morphology. EDAX analysis clearly confirmed that the presence of expected elements cadmium, oxygen and fluorine in the final product, in appropriate proportions. The electrical study showed that the minimum resistivity value of 1.9 × 10{sup −4} Ω cm with notable higher values of carrier concentration and mobility was achieved for 6 at.% of CdO:F film. Optical study exhibited that the band gap value of CdO film increases gradually with the increase in F-doping concentration, reaching maximum band gap value of 2.61 eV at 6 at.% and starts decreasing thereafter. Photoluminescence spectra depicted that the intensity of the emission peaks was significantly varied with doping concentrations. The high transparency, wide band gap energy, enhanced electrical properties and light sensitivity had been obtained infer that F-doped CdO thin films which find application in optoelectronic applications. Graphical abstract: .

36 MATERIALS SCIENCE↗