ABSTRACT
Microbial activity in crude oil and clear weed pesticide contaminated soil was investiga... more ABSTRACT Microbial activity in crude oil and clear weed pesticide contaminated soil was investigated by determining the levels of CO2 emission in the soil. Sandy loam soil was dispensed in 200g weight into ten 500ml kliner jar. Thereafter five levels of concentration of crude oil and pesticide (0%, 0.5%, 5%, 10% and 20%) were used to contaminate the soil samples, with 0% serving as a control. CO2 emission was measured at the weekly interval by means of titration with NaOH and HCL. Results obtained showed an increase in CO2 emission as contaminants concentration levels increased in the first week. In the second week, the quantity of CO2 evolved became generally low, with exception of 10% and 20% pesticide concentration which showed an increase in the amount of CO2 evolved. The third week of the experiment showed lower levels of CO2 emission in both concentrations of the contaminants but with an exception of 10% crude oil concentration which showed an increase in CO2 emission. The entire experiment showed that the clear weed pesticide (containing glyphosate) is a good carbon source for the soil microorganisms than crude oil within the soil sample. KEYWORDS: concentration, emission, contaminants, titration, increased, crude oil, clear weed pesticide.
Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. ... more Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. The strength of the interactions is characterized by the so-called ``fine structure constant", λ= e^2/vFɛ, which if ɛ˜1 is ˜2, indicating the absence of a small parameter for EM interactions and the presence of strong correlations. However, the salient signatures of correlations, such as spectral weight redistribution with doping, are not observed in graphene. To find out why, we used inelastic x-ray scattering to measure the collective excitations in single crystal graphite. Using some new data analysis methods, which ``remove" the van der Waals coupling between the layers, we reconstructed the density propagator for graphene, and then determined the dressing around an idealized point charge, e. The dressing is ˜2 nm in size and renormalizes the charge to eeff= 0.065 e greatly suppressing interactions. This suggests that, for length scales > 2 nm, graphene can be thought of as having a ``background" dielectric constant ɛ= 15.4, or a fine structure constant λ˜0.14. Our result explains the absence of spectral weight transfer with doping in graphene, the absence of a velocity divergence near EF, and a number of other effects.
Physical Review B Condensed Matter and Materials Physics, Apr 5, 2009
Inelastic x-ray scattering (IXS) is now a widely used technique for studying the dynamics of elec... more Inelastic x-ray scattering (IXS) is now a widely used technique for studying the dynamics of electrons in condensed matter. We previously posed a solution to the phase problem for IXS [P. Abbamonte , Phys. Rev. Lett. 92, 237401 (2004)] that allows explicit reconstruction of the density propagator of a system. The propagator represents, physically, the response of the system to an idealized, point perturbation, so provides direct, real-time images of electron motion with attosecond time resolution and Å -scale spatial resolution. Here we show that the images generated by our procedure, as it was originally posed, are spatial averages over all source locations. Within an idealized, atomiclike model, we show that in most cases a simple relationship to the complete, unaveraged response can still be determined. We illustrate this concept for recent IXS measurements of single-crystal graphite.
Nonlocal screening in highly-oriented pyrolitic graphite was investigated with inelastic x-ray sc... more Nonlocal screening in highly-oriented pyrolitic graphite was investigated with inelastic x-ray scattering. Measurements were performed over a sufficiently broad range of momentum and energy to permit complete inversion of the loss function, -Im [1/ε(k,phi)], allowing real-time, microscopic imaging of the induced electron density around a charged impurity. In addition, we found evidence for a sign change in the zero-frequency dielectric
The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconduc... more The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconducting (SC) orders. This competition resembles that between ordered stripes and superconductivity in High Tc superconductors. In particular, the CDW in 1T-TiSe2 has been shown to be suppressed, and SC stabilized, by intercalation of Cu. Raman studies have shown that the CDW order is also suppressed by hydrostatic pressure. Here, we present a detailed study of the suppression of the CDW in 1T-TiSe2 with high-pressure x-ray scattering. We found that pressure drives the system to a quantum critical point at Pc˜4GPa. The transition was found to be sharp along the temperature axis, but broadened along the pressure axis, suggesting the quantum phase transition is more sensitive to disorder than the classical one.
Eukaryotic translation initiation factor 5A (eIF-5A, older nomenclature, eIF-4D) is a highly cons... more Eukaryotic translation initiation factor 5A (eIF-5A, older nomenclature, eIF-4D) is a highly conserved protein that contains the unusual amino acid hypusine (N epsilon-(4-amino-2-hydroxybutyl)lysine). The biosynthesis of hypusine occurs posttranslationally in only this protein by modification of a single lysine residue (Lys50 in the human eIF-5A precursor). The basis for the specificity of this modification with respect to the substrate protein was investigated using fragments of eIF-5A precursor protein, each containing this lysine residue, as substrates for deoxyhypusine synthase, the first enzyme in hypusine synthesis. Proteolytic fragments (5-6 kDa) of ec-eIF-5A (the precursor form of eIF-5A produced in Escherichia coli by expression of the human eIF-5A cDNA) generated by specific cleavage by endoproteinases Arg-C, Asp-N, or Glu-C, did not act as substrates for deoxyhypusine synthesis. A series of truncated forms of the eIF-5A precursor protein generated by expression in E. coli of recombinant deletion constructs from the human eIF-5A cDNA were tested. Truncation of up to 9 amino acid residues (Met1-Thr9) from the NH2 terminus or 64 amino acid residues (Leu91-Lys154) from the COOH terminus did not significantly decrease the substrate reactivity, but removal of an additional 10 amino acids from either side did. Deletion of 34 amino acid residues (Met1-Lys34) from the NH2 terminus or of 84 amino acid residues (Asp71-Lys154) from the carboxyl terminus caused complete loss of substrate property. The results obtained thus far define the minimum domain of the eIF-5A precursor protein required for enzymatic deoxyhypusine synthesis as Phe30-Asp80, which corresponds to a region of high amino acid conservation in this protein throughout the eukaryotic kingdom.
We used inelastic X-ray scattering to measure the imaginary part of the density-density Green's f... more We used inelastic X-ray scattering to measure the imaginary part of the density-density Green's function, Im[χ(k;φ)], of a single crystal graphite sample along six direction in the Basal plane from [100] to [110]. To place Im[χ(k;φ)] on an absolute scale we calculate a scaling coefficient using the optical sum rule. The real part of χ(k;φ) is calculated via the Kramers-Kronig transformation. We use an inversion algorithm to map the data into real space at various time intervals with attosecond time resolution. The images of the density response we produced show hexagonal anisotropy, which arises from scattering between the K and K' points of the Brillouin zone. Analysis of the data at φ=0 provides us with the anisotripic induced electron density around a static impurity as function of distance. Integration of the local density around r=0 gives the effective charge of the impurity from which we deduced the background dielectric constant, ɛ∞, to be approximately 2.23.
Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. ... more Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. The strength of the interactions is characterized by the so-called ``fine structure constant", lambda= e^2/vFε, which if ε˜1 is ˜2, indicating the absence of a small parameter for EM interactions and the presence of strong correlations. However, the salient signatures of correlations, such as spectral weight redistribution
1T-TiSe2 is atypical quasi 2-dimensional CDW material showing a 2x2x2 superlattice modulation at ... more 1T-TiSe2 is atypical quasi 2-dimensional CDW material showing a 2x2x2 superlattice modulation at low temperature. It's is known that high pressure suppresses the CDW order and interestingly induces superconductivity. While it is not agreed what drives the CDW transition, it has been proposed that the CDW fluctuations are closely related to the emergence of superconductivity . Here we present a
We present new Raman and x-ray scattering evidence for the existence of a structural phase transi... more We present new Raman and x-ray scattering evidence for the existence of a structural phase transition at 50 K in KCuF3. Phonon modes associated with the F-ions in CuF6 octahedra soften with decreasing temperature down to 50 K, at which temperature there is a splitting of the Eg phonon. Above TN = 40 K, diffuse resonant magnetic scattering from critical
A prototypical orbital ordering material, the charge transfer insulator KCuF3 is believed to unde... more A prototypical orbital ordering material, the charge transfer insulator KCuF3 is believed to undergo orbital ordering at a temperature TOO ˜ 800 K. Recent Raman and X-ray measurements reveal a low-temperature structural transition just preceding the onset of three-dimensional magnetic ordering at TN ˜ 40 K. We present a model of how orbital, structural and magnetic fluctuations are coupled at
We used inelastic X-ray scattering to measure the imaginary part of the density-density Green'... more We used inelastic X-ray scattering to measure the imaginary part of the density-density Green's function, Im[chi(k;phi)], of a single crystal graphite sample along six direction in the Basal plane from [100] to [110]. To place Im[chi(k;phi)] on an absolute scale we calculate a scaling coefficient using the optical sum rule. The real part of chi(k;phi) is calculated via the Kramers-Kronig
The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconduc... more The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconducting (SC) orders. This competition resembles that between ordered stripes and superconductivity in High Tc superconductors. In particular, the CDW in 1T-TiSe2 has been shown to be suppressed, and SC stabilized, by intercalation of Cu. Raman studies have shown that the CDW order is also suppressed by hydrostatic pressure. Here, we present a detailed study of the suppression of the CDW in 1T-TiSe2 with high-pressure x-ray scattering. We found that pressure drives the system to a quantum critical point at Pc˜4GPa. The transition was found to be sharp along the temperature axis, but broadened along the pressure axis, suggesting the quantum phase transition is more sensitive to disorder than the classical one.
We present images, integrated photometry, and surface-brightness and color profiles for a total o... more We present images, integrated photometry, and surface-brightness and color profiles for a total of 1034 nearby galaxies recently observed by the Galaxy Evolution Explorer (GALEX) satellite in its far-ultraviolet (FUV; lambdaeff=1516{AA}) and near-ultraviolet (NUV; lambdaeff=2267{AA}) bands. Our catalog of objects is derived primarily from the GALEX Nearby Galaxies Survey (NGS) supplemented by galaxies larger than 1' in diameter serendipitously found in these fields and in other GALEX exposures of similar of greater depth. The sample analyzed here adequately describes the distribution and full range of properties (luminosity, color, star formation rate [SFR]) of galaxies in the local universe. (6 data files).
ABSTRACT
Microbial activity in crude oil and clear weed pesticide contaminated soil was investiga... more ABSTRACT Microbial activity in crude oil and clear weed pesticide contaminated soil was investigated by determining the levels of CO2 emission in the soil. Sandy loam soil was dispensed in 200g weight into ten 500ml kliner jar. Thereafter five levels of concentration of crude oil and pesticide (0%, 0.5%, 5%, 10% and 20%) were used to contaminate the soil samples, with 0% serving as a control. CO2 emission was measured at the weekly interval by means of titration with NaOH and HCL. Results obtained showed an increase in CO2 emission as contaminants concentration levels increased in the first week. In the second week, the quantity of CO2 evolved became generally low, with exception of 10% and 20% pesticide concentration which showed an increase in the amount of CO2 evolved. The third week of the experiment showed lower levels of CO2 emission in both concentrations of the contaminants but with an exception of 10% crude oil concentration which showed an increase in CO2 emission. The entire experiment showed that the clear weed pesticide (containing glyphosate) is a good carbon source for the soil microorganisms than crude oil within the soil sample. KEYWORDS: concentration, emission, contaminants, titration, increased, crude oil, clear weed pesticide.
Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. ... more Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. The strength of the interactions is characterized by the so-called ``fine structure constant", λ= e^2/vFɛ, which if ɛ˜1 is ˜2, indicating the absence of a small parameter for EM interactions and the presence of strong correlations. However, the salient signatures of correlations, such as spectral weight redistribution with doping, are not observed in graphene. To find out why, we used inelastic x-ray scattering to measure the collective excitations in single crystal graphite. Using some new data analysis methods, which ``remove" the van der Waals coupling between the layers, we reconstructed the density propagator for graphene, and then determined the dressing around an idealized point charge, e. The dressing is ˜2 nm in size and renormalizes the charge to eeff= 0.065 e greatly suppressing interactions. This suggests that, for length scales > 2 nm, graphene can be thought of as having a ``background" dielectric constant ɛ= 15.4, or a fine structure constant λ˜0.14. Our result explains the absence of spectral weight transfer with doping in graphene, the absence of a velocity divergence near EF, and a number of other effects.
Physical Review B Condensed Matter and Materials Physics, Apr 5, 2009
Inelastic x-ray scattering (IXS) is now a widely used technique for studying the dynamics of elec... more Inelastic x-ray scattering (IXS) is now a widely used technique for studying the dynamics of electrons in condensed matter. We previously posed a solution to the phase problem for IXS [P. Abbamonte , Phys. Rev. Lett. 92, 237401 (2004)] that allows explicit reconstruction of the density propagator of a system. The propagator represents, physically, the response of the system to an idealized, point perturbation, so provides direct, real-time images of electron motion with attosecond time resolution and Å -scale spatial resolution. Here we show that the images generated by our procedure, as it was originally posed, are spatial averages over all source locations. Within an idealized, atomiclike model, we show that in most cases a simple relationship to the complete, unaveraged response can still be determined. We illustrate this concept for recent IXS measurements of single-crystal graphite.
Nonlocal screening in highly-oriented pyrolitic graphite was investigated with inelastic x-ray sc... more Nonlocal screening in highly-oriented pyrolitic graphite was investigated with inelastic x-ray scattering. Measurements were performed over a sufficiently broad range of momentum and energy to permit complete inversion of the loss function, -Im [1/ε(k,phi)], allowing real-time, microscopic imaging of the induced electron density around a charged impurity. In addition, we found evidence for a sign change in the zero-frequency dielectric
The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconduc... more The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconducting (SC) orders. This competition resembles that between ordered stripes and superconductivity in High Tc superconductors. In particular, the CDW in 1T-TiSe2 has been shown to be suppressed, and SC stabilized, by intercalation of Cu. Raman studies have shown that the CDW order is also suppressed by hydrostatic pressure. Here, we present a detailed study of the suppression of the CDW in 1T-TiSe2 with high-pressure x-ray scattering. We found that pressure drives the system to a quantum critical point at Pc˜4GPa. The transition was found to be sharp along the temperature axis, but broadened along the pressure axis, suggesting the quantum phase transition is more sensitive to disorder than the classical one.
Eukaryotic translation initiation factor 5A (eIF-5A, older nomenclature, eIF-4D) is a highly cons... more Eukaryotic translation initiation factor 5A (eIF-5A, older nomenclature, eIF-4D) is a highly conserved protein that contains the unusual amino acid hypusine (N epsilon-(4-amino-2-hydroxybutyl)lysine). The biosynthesis of hypusine occurs posttranslationally in only this protein by modification of a single lysine residue (Lys50 in the human eIF-5A precursor). The basis for the specificity of this modification with respect to the substrate protein was investigated using fragments of eIF-5A precursor protein, each containing this lysine residue, as substrates for deoxyhypusine synthase, the first enzyme in hypusine synthesis. Proteolytic fragments (5-6 kDa) of ec-eIF-5A (the precursor form of eIF-5A produced in Escherichia coli by expression of the human eIF-5A cDNA) generated by specific cleavage by endoproteinases Arg-C, Asp-N, or Glu-C, did not act as substrates for deoxyhypusine synthesis. A series of truncated forms of the eIF-5A precursor protein generated by expression in E. coli of recombinant deletion constructs from the human eIF-5A cDNA were tested. Truncation of up to 9 amino acid residues (Met1-Thr9) from the NH2 terminus or 64 amino acid residues (Leu91-Lys154) from the COOH terminus did not significantly decrease the substrate reactivity, but removal of an additional 10 amino acids from either side did. Deletion of 34 amino acid residues (Met1-Lys34) from the NH2 terminus or of 84 amino acid residues (Asp71-Lys154) from the carboxyl terminus caused complete loss of substrate property. The results obtained thus far define the minimum domain of the eIF-5A precursor protein required for enzymatic deoxyhypusine synthesis as Phe30-Asp80, which corresponds to a region of high amino acid conservation in this protein throughout the eukaryotic kingdom.
We used inelastic X-ray scattering to measure the imaginary part of the density-density Green's f... more We used inelastic X-ray scattering to measure the imaginary part of the density-density Green's function, Im[χ(k;φ)], of a single crystal graphite sample along six direction in the Basal plane from [100] to [110]. To place Im[χ(k;φ)] on an absolute scale we calculate a scaling coefficient using the optical sum rule. The real part of χ(k;φ) is calculated via the Kramers-Kronig transformation. We use an inversion algorithm to map the data into real space at various time intervals with attosecond time resolution. The images of the density response we produced show hexagonal anisotropy, which arises from scattering between the K and K' points of the Brillouin zone. Analysis of the data at φ=0 provides us with the anisotripic induced electron density around a static impurity as function of distance. Integration of the local density around r=0 gives the effective charge of the impurity from which we deduced the background dielectric constant, ɛ∞, to be approximately 2.23.
Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. ... more Graphene is usually described as a two-dimensional system of weakly interacting, Dirac fermions. The strength of the interactions is characterized by the so-called ``fine structure constant", lambda= e^2/vFε, which if ε˜1 is ˜2, indicating the absence of a small parameter for EM interactions and the presence of strong correlations. However, the salient signatures of correlations, such as spectral weight redistribution
1T-TiSe2 is atypical quasi 2-dimensional CDW material showing a 2x2x2 superlattice modulation at ... more 1T-TiSe2 is atypical quasi 2-dimensional CDW material showing a 2x2x2 superlattice modulation at low temperature. It's is known that high pressure suppresses the CDW order and interestingly induces superconductivity. While it is not agreed what drives the CDW transition, it has been proposed that the CDW fluctuations are closely related to the emergence of superconductivity . Here we present a
We present new Raman and x-ray scattering evidence for the existence of a structural phase transi... more We present new Raman and x-ray scattering evidence for the existence of a structural phase transition at 50 K in KCuF3. Phonon modes associated with the F-ions in CuF6 octahedra soften with decreasing temperature down to 50 K, at which temperature there is a splitting of the Eg phonon. Above TN = 40 K, diffuse resonant magnetic scattering from critical
A prototypical orbital ordering material, the charge transfer insulator KCuF3 is believed to unde... more A prototypical orbital ordering material, the charge transfer insulator KCuF3 is believed to undergo orbital ordering at a temperature TOO ˜ 800 K. Recent Raman and X-ray measurements reveal a low-temperature structural transition just preceding the onset of three-dimensional magnetic ordering at TN ˜ 40 K. We present a model of how orbital, structural and magnetic fluctuations are coupled at
We used inelastic X-ray scattering to measure the imaginary part of the density-density Green'... more We used inelastic X-ray scattering to measure the imaginary part of the density-density Green's function, Im[chi(k;phi)], of a single crystal graphite sample along six direction in the Basal plane from [100] to [110]. To place Im[chi(k;phi)] on an absolute scale we calculate a scaling coefficient using the optical sum rule. The real part of chi(k;phi) is calculated via the Kramers-Kronig
The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconduc... more The dichalcogenides exhibit a close competition between charge density wave (CDW) and superconducting (SC) orders. This competition resembles that between ordered stripes and superconductivity in High Tc superconductors. In particular, the CDW in 1T-TiSe2 has been shown to be suppressed, and SC stabilized, by intercalation of Cu. Raman studies have shown that the CDW order is also suppressed by hydrostatic pressure. Here, we present a detailed study of the suppression of the CDW in 1T-TiSe2 with high-pressure x-ray scattering. We found that pressure drives the system to a quantum critical point at Pc˜4GPa. The transition was found to be sharp along the temperature axis, but broadened along the pressure axis, suggesting the quantum phase transition is more sensitive to disorder than the classical one.
We present images, integrated photometry, and surface-brightness and color profiles for a total o... more We present images, integrated photometry, and surface-brightness and color profiles for a total of 1034 nearby galaxies recently observed by the Galaxy Evolution Explorer (GALEX) satellite in its far-ultraviolet (FUV; lambdaeff=1516{AA}) and near-ultraviolet (NUV; lambdaeff=2267{AA}) bands. Our catalog of objects is derived primarily from the GALEX Nearby Galaxies Survey (NGS) supplemented by galaxies larger than 1' in diameter serendipitously found in these fields and in other GALEX exposures of similar of greater depth. The sample analyzed here adequately describes the distribution and full range of properties (luminosity, color, star formation rate [SFR]) of galaxies in the local universe. (6 data files).
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Papers by Young Joe
Microbial activity in crude oil and clear weed pesticide contaminated soil was investigated by determining the levels of CO2 emission in the soil. Sandy loam soil was dispensed in 200g weight into ten 500ml kliner jar. Thereafter five levels of concentration of crude oil and pesticide (0%, 0.5%, 5%, 10% and 20%) were used to contaminate the soil samples, with 0% serving as a control. CO2 emission was measured at the weekly interval by means of titration with NaOH and HCL. Results obtained showed an increase in CO2 emission as contaminants concentration levels increased in the first week. In the second week, the quantity of CO2 evolved became generally low, with exception of 10% and 20% pesticide concentration which showed an increase in the amount of CO2 evolved. The third week of the experiment showed lower levels of CO2 emission in both concentrations of the contaminants but with an exception of 10% crude oil concentration which showed an increase in CO2 emission. The entire experiment showed that the clear weed pesticide (containing glyphosate) is a good carbon source for the soil microorganisms than crude oil within the soil sample.
KEYWORDS: concentration, emission, contaminants, titration, increased, crude oil, clear weed pesticide.
Microbial activity in crude oil and clear weed pesticide contaminated soil was investigated by determining the levels of CO2 emission in the soil. Sandy loam soil was dispensed in 200g weight into ten 500ml kliner jar. Thereafter five levels of concentration of crude oil and pesticide (0%, 0.5%, 5%, 10% and 20%) were used to contaminate the soil samples, with 0% serving as a control. CO2 emission was measured at the weekly interval by means of titration with NaOH and HCL. Results obtained showed an increase in CO2 emission as contaminants concentration levels increased in the first week. In the second week, the quantity of CO2 evolved became generally low, with exception of 10% and 20% pesticide concentration which showed an increase in the amount of CO2 evolved. The third week of the experiment showed lower levels of CO2 emission in both concentrations of the contaminants but with an exception of 10% crude oil concentration which showed an increase in CO2 emission. The entire experiment showed that the clear weed pesticide (containing glyphosate) is a good carbon source for the soil microorganisms than crude oil within the soil sample.
KEYWORDS: concentration, emission, contaminants, titration, increased, crude oil, clear weed pesticide.