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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Size effect of added LaB{sub 6} particles on optical properties of LaB{sub 6}/Polymer composites

Modified LaB{sub 6} particles with sizes ranging from 50 nm to 400 nm were added into polymethyl methacrylate (PMMA) matrix in order to investigate the effect of added LaB{sub 6} particles on optical properties of LaB{sub 6}/PMMA composites. Method of in-situ polymerization was applied to prepare PMMA from raw material-methyl methacrylate (MMA), a process during which LaB{sub 6} particles were dispersed in MMA. Ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectrum was used to study optical properties of the as-prepared materials. The difference in particle size could apparently affect the composites' absorption of visible light around wavelength of 600 nm. Added LaB{sub 6} particles with size of about 70 nm resulted in the best optical properties among these groups of composites. - Graphical abstract: 70 nm LaB{sub 6} particles resulted in the best performance on absorption of VIS and NIR, which could not be apparently achieved by LaB{sub 6} particles beyond nano-scale. Highlights: Black-Right-Pointing-Pointer LaB{sub 6}/PMMA composites were prepared using the method of in-situ polymerization. Black-Right-Pointing-Pointer LaB{sub 6} particles added in MMA prolonged the time needed for its pre-polymerization. Black-Right-Pointing-Pointer Nanosized LaB{sub 6} particles could obviously absorb much NIR but little VIS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Synthesis and characterization of CuO nanofibers, and investigation for its suitability as blocking layer in ZnO NPs based dye sensitized solar cell and as photocatalyst in organic dye degradation

Electrospun copper based composite nanofibers were synthesized using the copper acetate/polyvinyl alcohol/water solution as starting material. Synthesized composite nanofibers were sintered at 500 Degree-Sign C to obtain CuO nanofibers. XRD, FTIR and XPS techniques were used to confirm the presence of pure CuO nanostructures. The effect of annealing cycle on the crystalline structure of the CuO nanofibers was analyzed and observed that the decrease in crystallite size with an increase in the dwelling time improved the orientation of the CuO crystallite. The blue-shift in the band-gap energies of CuO nanofibers was observed as a result of quantum confinement from bulk CuO (1.2 eV) to one dimensional (1D) nanostructures ({approx}1.746 eV). The catalytic activity of the CuO fibers for the degradation of methyl orange was carried out and as a blocking layer in ZnO based DSSC was fabricated and observed a {approx}25% increase in the current density. - Graphical abstract: The study on the suitability of highly crystalline CuO nanofibers as the blocking layer in ZnO based DSSC was demonstrated and fabricated with possible energy applications. Highlights: Black-Right-Pointing-Pointer CuO nanofibers were successfully synthesized by using electrospinning technique. Black-Right-Pointing-Pointer The effect of the dwelling time of the annealing cycle for the formation of the crystallite CuO nanofibers was analyzed. Black-Right-Pointing-Pointer A 25% increase in the current density was observed with the application of CuO as blocking layer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Low temperature fluorination of Sr{sub 3}Fe{sub 2}O{sub 7-x} with polyvinylidine fluoride: An X-ray powder diffraction and Moessbauer spectroscopy study

Fluorination of the Ruddlesden Popper phase, Sr{sub 3}Fe{sub 2}O{sub 7-x} by heat treatment with polyvinylidine fluoride (PVDF) gives a range of novel oxide fluoride compounds. Fluorination with 1 mol equivalent PVDF leads to a filling of the normal Ruddlesden Popper structure anion sites and a material of composition Sr{sub 3}Fe{sub 2}O{sub 5+x}F{sub 2-x} (x Almost-Equal-To 0.28(4)) which contains both Fe{sup 4+} and Fe{sup 3+}. Increasing the amount of PVDF to 2 mol equivalent leads to an increase in anion content due to filling of half the interstitial sites within the structure, with iron being completely reduced to Fe{sup 3+} leading to a composition Sr{sub 3}Fe{sub 2}O{sub 4}F{sub 4}. An increase in the amount of PVDF to Almost-Equal-To 3 mol equivalent leads to a further increase in unit cell volume, attributed to complete filling of the interstitial sites and a composition Sr{sub 3}Fe{sub 2}O{sub 3}F{sub 6}. {sup 57}Fe Moessbauer spectra in the temperature range 10-300 K demonstrated the complexity of the magnetic interactions in each of the three phases which reflect different local compositions of oxygen and fluorine around the iron ions thus influencing the superexchange pathways. - Graphical abstract: Low temperature (375 Degree-Sign C) fluorination of Sr{sub 3}Fe{sub 2}O{sub 7-x} with poly(vinylidene fluoride) leads to the production of three new Ruddlesden Popper oxide fluorides with progressive filling of the anion sites within the structure. Highlights: Black-Right-Pointing-Pointer The fluorination of Sr{sub 3}Fe{sub 2}O{sub 7-x} using PVDF. Black-Right-Pointing-Pointer The control of the fluorine content with amount of PVDF used. Black-Right-Pointing-Pointer The synthesis of three new Fe based oxide fluorides. Black-Right-Pointing-Pointer The identification of the structures of these oxide fluorides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Synthesis, structural and magnetic characterisation of the fully fluorinated compound 6H-BaFeO{sub 2}F

The compound 6H-BaFeO{sub 2}F (P6{sub 3}/mmc) was synthesised by the low temperature fluorination of 6H-BaFeO{sub 3-d} using polyvinylidenedifluoride (PVDF) as a fluorination agent. Structural characterisation by XRD and NPD suggests that the local positions of the oxygen and fluorine atoms vary with no evidence for ordering on the anion sites. This compound shows antiferromagnetic ordering at room temperature with antiparallel alignment of the magnetic moments along the c-axis. The use of PVDF also allows the possibility of tuning the fluorine content in materials of composition 6H-BaFeO{sub 3-d}F{sub y} to any value of 0<y{<=}1. In addition, the oxygen content, and therefore the iron oxidation state, can be tuned by applying different partial pressures of oxygen during the reaction. - Graphical abstract: The crystal structure of the hexagonal perovskite phase 6H-BaFeO{sub 2}F. Highlights: Black-Right-Pointing-Pointer The crystal structure of the hexagonal perovskite phase 6H-BaFeO{sub 2}F. Black-Right-Pointing-Pointer H-BaFeO{sub 2}F and 6H-BaFeO{sub 3-d}F{sub y} were prepared via low temperature fluorination using PVDF. Black-Right-Pointing-Pointer A structural investigation of the compounds BaFeO{sub 2}F is presented in detail. Black-Right-Pointing-Pointer This analysis suggests differences for the local coordination of O{sup 2-} and F{sup -} anions. Black-Right-Pointing-Pointer H-BaFeO{sub 2}F shows antiferromagnetic ordering at 300 K. Black-Right-Pointing-Pointer The magnetic moments align parallel to the a-axis.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Synthesis, structural and magnetic characterisation of the fluorinated compound 15R-BaFeO{sub 2}F

The compounds 15R-BaFeO{sub 2}F and 15R-BaFeO{sub 2.27}F{sub 0.5} have been synthesised by the low temperature fluorination of 15R-BaFeO{sub 3−d}F{sub 0.2} using polyvinylidenedifluoride (PVDF) as a fluorination agent. The materials have been structurally characterised by Rietveld analysis of the X-ray- and HRPD-powder neutron diffraction data. A detailed analysis of bond valence sums suggests that the oxide and fluoride ions order on the different anion sites. A reinvestigation of our recently published structure (Clemens et al., 2013) [34] of 6H-BaFeO{sub 2}F is also reported and incorporation of fluoride in h-type layers is also confirmed in this compound. The magnetic moments for 15R-BaFeO{sub 2}F and 15R-BaFeO{sub 2.25}F{sub 0.5} align in the a/b-plane with antiferromagnetic alignment of the moments between adjacent layers, and are flipped by 90° as compared to the precursor compound. 15R-BaFeO{sub 2}F exhibits very robust antiferromagnetism with a Néel temperature between 300 and 400 °C. - Graphical abstract: The crystal and magnetic structure of the perovskite phase 15R-BaFeO{sub 2}F. - Highlights: • 15R-BaFeO{sub 2}F and 15R-BaFeO{sub 2.27}F{sub 0.5}were prepared via low temperature fluorination using PVDF. • A structural investigation of the compounds BaFeO{sub 2}F is presented in detail. • This analysis suggests ordering of O{sup 2−} and F{sup −} anions between different layers. • 15R-BaFeO{sub 2}F shows antiferromagnetic ordering at 300 K with T{sub N} ∼300–400 °C. • The magnetic moments align in the a/b-plane.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Effects of CO{sub 2} activation on electrochemical performance of microporous carbons derived from poly(vinylidene fluoride)

In this work, we have prepared microporous carbons (MPCs) derived from poly(vinylidene fluoride) (PVDF), and the physical activation of MPCs using CO{sub 2} gas is subsequently carried out with various activation temperatures to investigate the electrochemical performance. PVDF is successfully converted into MPCs with a high specific surface area and well-developed micropores. After CO{sub 2} activation, the specific surface areas of MPCs (CA-MPCs) are enhanced by 12% compared with non-activated MPCs. With increasing activation temperature, the micropore size distributions of A-MPCs also become narrower and shift to larger pore size. It is also confirmed that the CO{sub 2} activation had developed the micropores and introduced the oxygen-containing groups to MPCs′ surfaces. From the results, the specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on CA-MPCs are distinctly improved through CO{sub 2} activation. The highest specific capacitance of the A-MPCs activated at 700 °C is about 125 F/g, an enhancement of 74% in comparison with NA-MPCs, at a discharge current of 2 A/g in a 6 M KOH electrolyte solution. We also found that micropore size of 0.67 nm has a specific impact on the capacitance behaviors, besides the specific surface area of the electrode samples. - Graphical abstract: The A-MPC samples with high specific surface area (ranging from 1030 to 1082 m{sup 2}/g), corresponding to micropore sizes of 0.67 and 0.72 nm, and with the amount of oxygen-containing groups ranging from 3.2% to 4.4% have been evaluated as electrodes for EDLC applications. . Display Omitted - Highlights: • Microporous carbons (MPCs) were synthesized without activation process. • Next, we carried out the CO{sub 2} activation of MPCs with activation temperatures. • It had developed the micropores and introduced the O-functional groups to MPCs. • The highest specific capacitance: 125 F/g, an increase of 74% compared to MPCs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Structural characterization of a new vacancy ordered perovskite modification found for Ba{sub 3}Fe{sub 3}O{sub 7}F (BaFeO{sub 2.333}F{sub 0.333}): Towards understanding of vacancy ordering for different perovskite-type ferrites

The new vacancy ordered perovskite-type compound Ba{sub 3}Fe{sub 3}O{sub 7}F (BaFeO{sub 2.33}F{sub 0.33}) was prepared by topochemical low-temperature fluorination of Ba{sub 2}Fe{sub 2}O{sub 5} (BaFeO{sub 2.5}) using stoichiometric amounts of polyvinylidene difluoride (PVDF). The vacancy order was found to be unique so far for perovskite compounds, and the connectivity pattern can be explained by the formula Ba{sub 3}(FeX{sub 6/2}) (FeX{sub 5/2}) (FeX{sub 3/2}X{sub 1/1}), with X=O/F. Mössbauer measurements were used to confirm the structural analysis and agree with the presence of Fe{sup 3+} in the above mentioned coordination environments. Group–subgroup relationships were used to build a starting model for the structure solution and to understand the relationship to the cubic perovskite structure. Furthermore, a comparison of a variety of vacancy-ordered iron-containing perovskite-type structures is given, highlighting the factors which favour one structure type over the other depending on the composition. - Graphical abstract: The crystal structure of Ba{sub 3}Fe{sub 3}O{sub 7}F in comparison to other perovskite type ferrites. - Highlights: • The crystal structure of Ba{sub 3}Fe{sub 3}O{sub 7}F in comparison to other perovskite type ferrites. • Ba{sub 3}Fe{sub 3}O{sub 7}F was synthesized by low temperature fluorination of Ba{sub 2}Fe{sub 2}O{sub 5}. • Ba{sub 3}Fe{sub 3}O{sub 7}F shows a unique vacancy order not found for other perovskite type compounds. • The structure of Ba{sub 3}Fe{sub 3}O{sub 7}F was solved using group–subgroup relationships. • A systematic comparison to other ferrite type compounds reveals structural similarities and differences. • The A-site coordination of the cation is shown to play an important role for the type of vacancy order found.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Simulated annealing reconstruction and characterization of the three-dimensional microstructure of a LiCoO{sub 2} Lithium-ion battery cathode

We adapt the simulated annealing approach for reconstruction of the 3D microstructure of a LiCoO{sub 2} cathode from a commercial Li-ion battery. The real size distribution curve of LiCoO{sub 2} particles is applied to regulate the reconstruction process. By discretizing a 40 × 40 × 40 μm cathode volume with 8,000,000 numerical cubes, the cathode involving three individual phases: 1) LiCoO{sub 2} as active material, 2) pores or electrolyte, and 3) additives (polyvinylidene fluoride + carbon black) is reconstructed. The microstructural statistical properties required in the reconstruction process are extracted from 2D focused ion beam/scanning electron microscopy images or obtained by analyzing the powder mixture used to make the cathode. Characterization of the reconstructed cathode gives important structural and transport properties including the two-point correlation functions, volume-specific surface area between phases, tortuosity and geometrical connectivity of individual phase. - Highlights: • Simulated annealing approach is adapted for 3D reconstruction of LiCoO{sub 2} cathode. • Real size distribution of LiCoO{sub 2} particles is applied in reconstruction process. • Reconstructed cathode accords with real one at important statistical properties. • Effective electrode-characterization approaches have been established. • Extensive characterization gives important structural properties, say, tortuosity.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Porous Si spheres encapsulated in carbon shells with enhanced anodic performance in lithium-ion batteries

Highlights: • In situ magnesiothermic reduction route for the formation of porous Si@C spheres. • Unique microstructural characteristics of both porous sphere and carbon matrix. • Enhanced anodic performance in term of cycling stability for lithium-ion batteries. - Abstract: A novel type of porous Si–C micro/nano-hybrids, i.e., porous Si spheres encapsulated in carbon shells (porous Si@C spheres), has been constructed through the pyrolysis of polyvinylidene fluoride (PVDF) and subsequent magnesiothermic reduction methodology by using SiO{sub 2} spheres as precursors. The as-synthesized porous Si@C spheres have been applied as anode materials for lithium-ion batteries (LIBs), and exhibit enhanced anodic performance in term of cycling stability compared with bare Si spheres. For example, the porous Si@C spheres are able to exhibit a high reversible capacity of 900.0 mA h g{sup −1} after 20 cycles at a current density of 0.05 C (1 C = 4200 mA g{sup −1}), which is much higher than that of bare Si spheres (430.7 mA h g{sup −1})

36 MATERIALS SCIENCE↗
DOE OSTI2014

A dual strategy for improving lithium storage performance, a case of Fe{sub 2}O{sub 3}

Graphical abstract: The α-Fe{sub 2}O{sub 3} nanoellipse with180–230 nm (edge length) and 140–170 nm (edge width) has been synthesize and tested as anode material for LIBs. The α-Fe{sub 2}O{sub 3} nanoellipse electrode with sodium alginate (SA) binder exhibits greatly enhanced performance for lithium storage. - Highlights: • α-Fe{sub 2}O{sub 3} nanoellipses were fabricated by a simple hydrothermal method with glycine. • The elliptical α-Fe{sub 2}O{sub 3}-SA electrode exhibits enhanced lithium storage performance. • The reason for the enhanced performance of elliptical α-Fe{sub 2}O{sub 3}-SA was investigated. - Abstract: In this paper, we developed a dual strategy, the nanostructure engineering of active material and the proper choice of binder, to achieve excellent lithium storage performance of transition metal oxides. α-Fe{sub 2}O{sub 3} nanoellipses with a mean size of 180–230 nm (edge length) and 140–170 nm (edge width) were fabricated by a simple hydrothermal method in the presence of glycine. When tested as anode material for lithium ion batteries (LIBs), the α-Fe{sub 2}O{sub 3} nanoellipse electrode with sodium alginate (SA) binder exhibits greatly enhanced performance for lithium storage. The capacity could be retained as high as 1164 mA h g{sup −1} at a current density of 100 mA g{sup −1} for over 60 cycles. Even cycled at high current densities of 2000–5000 mA g{sup −1}, high capacities of 443–628 mA h g{sup −1} can be achieved, whereas the electrode with the conventional poly(vinylidene fluoride) (PVDF) binder suffers from rapid capacity decay under the same test conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Control of ferromagnetism in (In{sub 0.9}Fe{sub 0.1}){sub 2}O{sub 3} via F doping of electron carriers

Highlights: • F doping was achieved by a process of low temperature reaction with PVDF. • RTFM was obtained in the F-doped (In{sub 0.9}Fe{sub 0.1}){sub 2}O{sub 3.} • Magnetism and electric resistivity can be controlled by the content of doped F. • The FM can be ascribed to a long range exchange interaction induced by carriers. - Abstract: Ferromagnetism in (In{sub 0.9}Fe{sub 0.1}){sub 2}O{sub 3} was obtained by fluorine (F) doping. The ferromagnetism can be controlled by changing the electron carrier concentration via F doping. With increasing the F concentration, the electron carrier concentration increases, and samples undergo a paramagnetic insulator to ferromagnetic metal transition. For the ferromagnetic samples, the anomalous Hall effect (AHE) was observed. These results indicate that electron carriers play an important role in inducing the ferromagnetism.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Zirconium dioxide nanofilled poly(vinylidene fluoride-hexafluoropropylene) complexed with lithium trifluoromethanesulfonate as composite polymer electrolyte for electrochromic devices

Highlights: • Successful synthesis of electrolyte by blending PVdF-HFP, ZrO{sub 2} and LiCF{sub 3}SO{sub 3}. • ZrO{sub 2} increased electrolyte conductivity by two orders of magnitude. • ZrO{sub 2} doubled bulk mechanical strength of electrolyte in terms of Young’s modulus. • Electrolytes gave a optimum optical transmittance of 52.6%. - Abstract: Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) polymer electrolyte containing zirconium dioxide nanocrystals (ZrO{sub 2}-NC) and lithium trifluoromethanesulfonate (LiCF{sub 3}SO{sub 3}) has been synthesized using the conventional solution casting method. The addition of ZrO2-NC into the polymeric substrate gave remarkable properties in terms of the electrolyte’s ionic conductivity as well as its bulk mechanical strength. The enhanced amorphicity of the polymeric substrate due to ZrO{sub 2} and the nanofiller’s high dielectric constant make an excellent combination to increase the ionic conductivity (above 10{sup −4} S cm{sup −1}). Increasing the nanofiller content raises the ionic conductivity of the electrolyte by two orders of magnitude of which the optimum is 2.65 × 10{sup −4} S cm{sup −1} at 13.04 wt% ZrO{sub 2}-NC loading. Also, the Young’s modulus, an indicator of electrolyte’s mechanical stability, dramatically increased to 207 MPa upon loading 13.04 wt% ZrO{sub 2}-NC. Using UV–vis spectroscopy, the electrolytes with 13.04% ZrO{sub 2}-NC scanned from 200–800 nm wavelengths exhibited a maximum optical transmittance of 52.6% at 10 μm film thickness. The enhanced conductivity, high mechanical strength and reasonable optical transmittance shown by our composite polymer electrolyte make an excellent electrolyte for future energy saving smart windows such as electrochromic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Poly(vinylidene fluoride)/ CaCu{sub 3}Ti{sub 4}O{sub 12} and La doped CaCu{sub 3}Ti{sub 4}O{sub 12} composites with improved dielectric and mechanical properties

Highlights: • High ϵ′ PVDF/CCTO and La doped CCTO composites prepared by Extrusion. • With addition of ceramic, there is substantial increase in the ϵ′ of matrix PVDF. • Composites exhibit double relaxation behavior. - Abstract: Melt extrusion process has been used to prepare high relative permittivity, ϵ' PVDF–CCTO and PVDF–LaCCTO composites. Phase composition has been studied using powder X-ray diffraction (XRD). Microstructural, dielectric and mechanical properties have also been studied. Young's modulus of PVDF increases with the ceramic reinforcement. Dielectric measurements are made in the frequency range 10{sup −2}–10{sup 6} Hz using two probe Novocontrol impedance analyser (ZG4) from room temp to 120 °C to study the dielectric relaxation. There is a substantial increase in ϵ' of the matrix PVDF on addition of LaCCTO.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Electrospun montmorillonite modified poly(vinylidene fluoride) nanocomposite separators for lithium-ion batteries

Highlights: • Composite separators of PVDF and MMT for lithium-ion batteries were electrospun. • Thermal dimensional stability and tensile property of composite separators get improved. • Presence of montmorillonite promotes electrical properties of PVDF fibrous separators. • Batteries consisting of PVDF/MMT-5% separator achieve the best performance. - Abstract: Composite separators of poly(vinylidene fluoride) (PVDF) with different contents of montmorillonite (MMT) for Li-ion batteries have been fabricated by electrospinning. The morphology, function group, crystallinity, and mechanical properties of membranes were investigated by scanning electron microscope (SEM), Fourier Transform infrared spectra (FT-IR), differential scanning calorimetry (DSC), and tensile test, respectively. Interlayer spacing of MMT in polymer was characterized by X-ray diffraction (XRD). In addition, the results of electrochemical measurements suggest that PVDF/MMT-5% composite membrane has maximum ionic conductivity of 4.2 mS cm{sup −1}, minimum interfacial resistance of 97 Ω, and excellent electrochemical stability. The cell comprising PVDF/MMT-5% composite membrane shows higher capacity and more stable cycle performance than the one using commercial Celgard PP membrane.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A superior composite gel polymer electrolyte of Li7La3Zr2O12- poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for rechargeable solid-state lithium ion batteries

Highlights: • Solid electrolyte LLZO dispersed in PVDF-HFP matrix is studied. • Garnet inorganic fillers enhance the transport number of Li{sup +}. • Composite polymer electrolytes show superior electrochemical performance. • Coin cells (Li/PVDF-HFP: LLZO/LiFePO{sub 4}) show good cycling performance. - Abstract: High-quality solid electrolyte is essential for the growing need of lithium ion batteries. Herein, we report a novel organic-inorganic composite electrolyte based on Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} ceramic powder incorporated into PVDF-HFP through a simple combined method. At room temperature, the composite polymer electrolyte (CPE) possesses a good ionic transmission improvement of 3.71 × 10{sup −4} S cm{sup −1}. The CPE behaves a fine lithium ion transference number of 0.58 and an electrochemical window of up to 4.65 V. CPEs display meliorative electrochemical stability compared to pure PVDF-HFP electrolyte. The cathode presents an excellent initial discharge capacity of 163.1 mAh g{sup −1} at 0.2 C in Li/CPE/LiFePO{sub 4} cell. The cell with CPE displays much better capacity retention than that with pure PVDF-HFP electrolyte. The Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} modified PVDF-HFP is a promising electrolyte for lithium ion batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Advancing biological processing for valorization of plastic wastes

We report the useful applications of plastics are as significant as the problems associated with their disposal. Current waste management strategies are ineffective at preventing the flow of plastics into landfills, wastewater treatment, and the environment. Despite the importance of recycling technologies, most plastics are used for consumables and are discarded after limited usage. Moreover, only certain plastics are recycled, and those that are generally yield lower value products. Discovering alternative routes for valorizing plastic wastes is essential. Emerging research involves the use of biocatalysts (i.e., enzymes and microorganisms) to produce valuable products like specialty polymers, biosurfactants, and drug precursors from these feedstocks. These bioprocesses commonly integrate physio-chemical pretreatments (to generate biologically reactive intermediates) and biological upgrading (to convert intermediates to products). Herein, publications that explore plastic deconstruction technologies and bioprocesses are reviewed with an emphasis on plastic waste valorization. Understanding how microorganisms metabolize the intermediates of plastic degradation and manage their inhibitory effects is a prerequisite for engineering bioprocesses. For these heterogeneous wastes, a paradigm shift from axenic cultivation of microorganisms to cultivation of microbial consortia may benefit conversion efficiency and stress resilience. Thus, a summary is provided for metabolic pathways and constituent enzymes required to synthesize biofuels, biomaterials, and chemicals from biologically reactive intermediates. Colossal challenges associated with the use of plastics as feedstocks for direct biological processing highlight the need for integrating physical, chemical, and biological technologies.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

The effect of interferon-{alpha} on the expression of cytochrome P450 3A4 in human hepatoma cells

Interferon {alpha} (IFN{alpha}) is used to treat malignancies and chronic viral infections. It has been found to decrease the rate of drug metabolism by acting on cytochrome P450 enzymes, but no studies have investigated the consequences of IFN{alpha} treatment on the CYP3A4 isoform, responsible for the metabolism of a majority of drugs. In this study, we have examined the effect of IFN{alpha} on CYP3A4 catalytic activity and expression in human hepatoma cells. We found that IFN{alpha} inhibits CYP3A4 activity and rapidly down-regulates the expression of CYP3A4, independent of de novo protein synthesis. Pharmacologic inhibitors and a dominant-negative mutant expression plasmid were used to dissect the molecular pathway required for CYP3A4 suppression, revealing roles for Jak1 and Stat1 and eliminating the involvement of the p38 mitogen-activated and extracellular regulated kinases. Treatment of hepatoma cells with IFN{alpha} did not affect the nuclear localization or relative abundance of Sp1 and Sp3 transcription factors, suggesting that the suppression of CYP3A4 by IFN{alpha} does not result from inhibitory Sp3 out-competing Sp1. To our knowledge, this is the first report that IFN{alpha} down-regulates CYP3A4 expression largely through the JAK-STAT pathway. Since IFN{alpha} suppresses CYP3A4 expression, caution is warranted when IFN{alpha} is administered in combination with CYP3A4 substrates to avoid the occurrence of adverse drug interactions.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2011

Proteomic analysis of hippocampal proteins of F344 rats exposed to 1-bromopropane

1-Bromopropane (1-BP) is a compound used as an alternative to ozone-depleting solvents and is neurotoxic both in experimental animals and human. However, the molecular mechanisms of the neurotoxic effects of 1-BP are not well known. To identify the molecular mechanisms of 1-BP-induced neurotoxicity, we analyzed quantitatively changes in protein expression in the hippocampus of rats exposed to 1-BP. Male F344 rats were exposed to 1-BP at 0, 400, or 1000 ppm for 8 h/day for 1 or 4 weeks by inhalation. Two-dimensional difference in gel electrophoresis (2D-DIGE) combined with matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) were conducted to detect and identify protein modification. Changes in selected proteins were further confirmed by western blot. 2D-DIGE identified 26 proteins with consistently altered model (increase or decrease after both 1- and 4-week 1-BP exposures) and significant changes in their levels (p < 0.05; fold change {>=} {+-} 1.2) at least at one exposure level or more compared with the corresponding controls. Of these proteins, 19 were identified by MALDI-TOF-TOF/MS. Linear regression analysis of 1-BP exposure level identified 8 differentially expressed proteins altered in a dose-dependent manner both in 1- and 4-week exposure experiments. The identified proteins could be categorized into diverse functional classes such as nucleocytoplasmic transport, immunity and defense, energy metabolism, ubiquitination-proteasome pathway, neurotransmitter and purine metabolism. Overall, the results suggest that 1-BP-induced hippocampal damage involves oxidative stress, loss of ATP production, neurotransmitter dysfunction and inhibition of ubiquitination-proteasome system. -- Highlights: Black-Right-Pointing-Pointer 1-BP modified hippocampal proteome in rat and 19 altered proteins were identified. Black-Right-Pointing-Pointer Expression of Ran, TPI, HSP60, PSMA1, ECH1, TPI, B-CK and DJ-1 was changed by 1-BP. Black-Right-Pointing-Pointer 1-BP exposure might change biological processes such as nucleocytoplasmic transport.

60 APPLIED LIFE SCIENCES↗