Duck Chung | Argonne National Laboratory (original) (raw)

Papers by Duck Chung

Research paper thumbnail of Symmetry measurements of the order parameter of BaFe2As2 superconductors

Since the discovery of the Fe-pnictide superconductors, extensive efforts have been directed towa... more Since the discovery of the Fe-pnictide superconductors, extensive efforts have been directed toward understanding the symmetry and mechanism of the superconducting pairing. Extended s-wave models, predominately the s± model, are predicted by many theories, but a definitive experimental verification has been elusive. We are using phase-sensitive Josephson interferometry to test for magnitude and phase anisotropy in electron (Co-doped) and hole (K-doped) BaFe2As2 single crystals. In particular, we are looking in the heavily K-doped regime that is predicted to exhibit d-wave symmetry characterized by a sign change in the order parameter. We are also searching for proximity-induced structure in the density-of-states of an s-wave superconductor proximity-coupled to an Fe-pnictide superconductor that is predicted to arise for s± pairing (Koshelev, 2012).

Research paper thumbnail of Crystal Growth, Structures, and Properties of the Complex Borides, LaOs2Al2B and La2Os2AlB2

Inorganic chemistry, Jan 17, 2015

Single crystals of two novel quaternary metal borides, LaOs2Al2B and La2Os2AlB2, have been grown ... more Single crystals of two novel quaternary metal borides, LaOs2Al2B and La2Os2AlB2, have been grown from La/Ni eutectic fluxes. LaOs2Al2B crystallizes in tetragonal space group P4/mmm with the CeCr2Si2C-type structure, and lattice parameters a = 4.2075(6) Å and c = 5.634(1) Å. La2Os2AlB2 exhibits a new crystal structure in monoclinic space group C2/c with lattice parameters a = 16.629(3) Å, b = 6.048(1) Å, c = 10.393(2) Å, and β = 113.96(3)°. Both structures are three-dimensional frameworks with unusual coordination (for solid-state compounds) of the boron atoms by transition metal atoms. The boron atom is square planar in LaOs2Al2B, whereas it exhibits linear and T-shaped geometries in La2Os2AlB2. Electrical resistivity measurements reveal poor metal behavior (ρ300 K ∼ 900 μΩ cm) for La2Os2AlB2, consistent with the electronic band structure calculations, which also predict a metallic character for LaOs2Al2B.

Research paper thumbnail of In situ studies of a platform for metastable inorganic crystal growth and materials discovery

Proceedings of the National Academy of Sciences of the United States of America, Jan 29, 2014

Rapid shifts in the energy, technological, and environmental demands of materials science call fo... more Rapid shifts in the energy, technological, and environmental demands of materials science call for focused and efficient expansion of the library of functional inorganic compounds. To achieve the requisite efficiency, we need a materials discovery and optimization paradigm that can rapidly reveal all possible compounds for a given reaction and composition space. Here we provide such a paradigm via in situ X-ray diffraction measurements spanning solid, liquid flux, and recrystallization processes. We identify four new ternary sulfides from reactive salt fluxes in a matter of hours, simultaneously revealing routes for ex situ synthesis and crystal growth. Changing the flux chemistry, here accomplished by increasing sulfur content, permits comparison of the allowable crystalline building blocks in each reaction space. The speed and structural information inherent to this method of in situ synthesis provide an experimental complement to computational efforts to predict new compounds and...

Research paper thumbnail of Resonant spin excitation in Ba1-xKxFe2As2

In the iron arsenides, superconductivity occurs when the antiferromagnetism of a parent compound ... more In the iron arsenides, superconductivity occurs when the antiferromagnetism of a parent compound has been suppressed by chemical doping. We have investigated the evolution of the magnetic response with potassium doping in Ba1-xKxFe2As2. In the parent compound (x = 0), there is evidence of a column of inelastic scattering at the AF wavevector, Q = 1.2å-1, consistent with a steep dispersion of gapped spin waves. A similar inelastic column is seen in the normal phase in the x = 0.4 compound, but it persists to lower energy transfer. However, at the superconducting transition of 38K, there is a transfer of spectral weight into an excitation localized at Q = 1.2å-1 and phi = 14meV [A. D. Christianson et al, Nature, in press]. Such resonant spin excitations, which are a universal feature of the copper oxide superconductors and seen in several heavy fermion superconductors, provide evidence that the energy gap has unconventional symmetry, with opposite sign on portions of the Fermi surface...

Research paper thumbnail of Heat capacity jump at <span class="aps-inline-formula"><math><msub><mi>T</mi><mi>c</mi></msub></math></span> and pressure derivatives of superconducting transition temperature in the Ba<span class="aps-inline-formula"><math><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></ma...

Physical Review B, 2013

We present the evolution of the initial (up to ∼10 kbar) hydrostatic pressure dependencies of T c... more We present the evolution of the initial (up to ∼10 kbar) hydrostatic pressure dependencies of T c and of the ambient pressure jump in the heat capacity associated with the superconducting transition as a function of K doping in the Ba 1−x K x Fe 2 As 2 family of iron-based superconductors. The pressure derivatives show a weak but distinct anomaly near x ∼ 0.7. In the same concentration region, C p | Tc deviates from the C p ∝ T 3 scaling found for most BaFe 2 As 2 -based superconductors. These results are consistent with a possible significant modification of the superconducting state, occurring near x ∼ 0.7.

Research paper thumbnail of Unconventional superconductivity in Ba0.6K0.4Fe2As2 from inelastic neutron scattering

Research paper thumbnail of Etching characteristics of photoresist and low-k dielectrics by Ar/O2 ferrite-core inductively coupled plasmas

Microelectronic Engineering, 2008

We have investigated the characteristics of Ar/O 2 plasmas in terms of the photoresist (PR) and l... more We have investigated the characteristics of Ar/O 2 plasmas in terms of the photoresist (PR) and low-k material etching using a ferritecore inductively coupled plasma (ICP) etcher. We found that the O 2 /(O 2 + Ar) gas flow ratio significantly affected the PR etching rate and the PR to low-k material etch selectivity. Fourier transform infrared spectroscopy (FTIR) and HF dipping test indicated that the etching damage to the low-k material decreased with decreasing O 2 /(O 2 + Ar) gas flow ratio.

Research paper thumbnail of Study of SnO2 Nanorods Coated Using the PECVD Technique

Journal of the Korean Physical Society, 2007

Journal of the Korean Physical Society, Vol. 50, No. 4, April 2007, pp. 1085~1089 ... Study of Sn... more Journal of the Korean Physical Society, Vol. 50, No. 4, April 2007, pp. 1085~1089 ... Study of SnO2 Nanorods Coated Using the PECVD Technique ... Hyoun Woo Kim,∗ Seung Hyun Shim, Jong Woo Lee, Dong Yeop Shin, Chang Hyun Wi, Byung Don Yoo and Chongmu ...

Research paper thumbnail of Superconductivity in the Narrow-Gap Semiconductor CsBi 4 Te 6

Journal of the American Chemical Society, 2013

Superconductivity was discovered in the narrow-gap semiconductor CsBi 4 Te 6 . A superconducting ... more Superconductivity was discovered in the narrow-gap semiconductor CsBi 4 Te 6 . A superconducting transition around 4.4 K was observed for p-type samples in temperature-dependent resistivity and magnetic susceptibility data. Stoichiometric CsBi 4 Te 6 is not a superconductor. A remarkably high critical field of ∼10 T was estimated from the field-dependent resistivity data. The strongly anisotropic CsBi 4 Te 6 system is monoclinic and the first member of a larger homologous series Cs 4 [Bi 2n+4 Te 3n+6 ] that exhibits unconventional superconductivity, suggesting that proper doping of the homologous series may create a novel class of superconductors from semiconductors.

Research paper thumbnail of Structure and Thermoelectric Properties of the New Quaternary Bismuth Selenides A1−xM4−xBi11+xSe21 (A=K and Rb and Cs; M=Sn and Pb)—Members of the Grand Homologous Series Km(M6Se8)m(M5+nSe9+n)

Chemistry, 2001

Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepa... more Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepared by direct combination of A2Se, Bi2Se3, Sn (or Pb), and Se at 800 degrees C. The single-crystal structures of K(0.54)Sn(3.54)Bi(11.46)Se21, K(1.46)Pb(3.08)Bi(11.46)Se21, Rb(0.69)Pb(3.69)Bi(11.31)Se21, and Cs(0.65)Pb(3.65)Bi(11.35)Se21 were determined. The compounds A(1-x)M(4-x)Bi(11+x) Se21 crystallize in a new structure type with the monoclinic space group C2/m, in which building units of the Bi2Te3 and NaCl structure type join to give rise to a novel kind of three-dimensional anionic framework with alkali-ion-filled tunnels. The building units are assembled from distorted, edge-sharing (Bi,Sn)Se6 octahedra. Bi and Sn/Pb atoms are disordered over the metal sites of the chalcogenide network, while the alkali site is not fully occupied. A grand homologous series Km(M6Se8)m(M(5+n)Se(9+n)) has been identified of which the compounds A(1-x)M(4-x)Bi(11+x)Se21 are members. We discuss here the crystal structure, charge-transport properties, and very low thermal conductivity of A(1-x)M(4-x)Bi(11+x)Se21.

Research paper thumbnail of Topotactic Redox Chemistry of NaFeAs in Water and Air and Superconducting Behavior with Stoichiometry Change

Chemistry of Materials, 2010

We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na defic... more We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na deficient. The oxidation of NaFeAs progresses differently in water and in air. In water the material oxidizes slowly and slightly retaining the original anti-PbFCl structure. In air NaFeAs oxidizes topotactically quickly and extensively transforming to the ThCrSi structure type. Water acts as a mild oxidizing agent on the FeAs layer by extracting electrons and Na{sup +} cations from the structure, while oxidation in air is more extensive and leads to change in structure type from NaFeAs to NaFeAs. The superconducting transition temperature moves dramatically during the oxidation process. Exposed to water for an extended time period NaFeAs shows a substantial increase in T{sub c} up to 25 K with contraction of unit cell volume. NaFeAs, the air oxidized product, shows T{sub c} of 12 K. We report detailed characterization of the redox chemistry and transformation of NaFeAs in water and air using single crystal and powder X-ray diffraction, magnetization studies, transmission electron microscopy, Moessbauer spectroscopy, pOH and elemental analysis.

Research paper thumbnail of Understanding Nanostructures in Thermoelectric Materials: An Electron Microscopy Study of AgPb 18 SbSe 20 Crystals

Chemistry of Materials, 2010

The characterization and understanding of the presence of nanostructuring in bulk thermoelectric ... more The characterization and understanding of the presence of nanostructuring in bulk thermoelectric materials requires real space atomic level information. We report electron diffraction and high-resolution transmission electron microscopy studies of crystals of the system AgPbSbSe (=18PbSe + AgSbSe) which reveal that this system is nanostructured rather than a solid solution. Nanocrystals of varying sizes are found, endotaxially grown in the

Research paper thumbnail of Selective Substitution of Cr in CaFe 4 As 3 and Its Effect on the Spin Density Wave

Chemistry of Materials, 2010

Single crystals of CaCr{sub 0.84}Fe{sub 3.16}As, a Cr substituted analog of CaFeAs, were grown fr... more Single crystals of CaCr{sub 0.84}Fe{sub 3.16}As, a Cr substituted analog of CaFeAs, were grown from Sn flux and characterized with single crystal neutron diffraction. CaCr{sub 0.84}Fe{sub 3.16}As crystallizes in the orthorhombic space group Pnma with a three-dimensional framework, where Fe, Cr, and As form a covalent channel-like network with Ca{sup 2+} cations residing in the channels. CaCr{sub 0.84}Fe{sub 3.16}As has

Research paper thumbnail of Species-Specific Detection of Listeria monocytogenes Using Polymerase Chain Reaction Assays Targeting the prfA Virulence Gene Cluster

Bioscience, Biotechnology, and Biochemistry, 2009

Sequence comparison of individual genes in the prfA virulence gene cluster (pVGC), a central viru... more Sequence comparison of individual genes in the prfA virulence gene cluster (pVGC), a central virulence gene cluster, from different Listeria species indicated that priming sites within the genes appeared to be specific for Listeria monocytogenes exclusively. Therefore, the pVGC was targeted for polymerase chain reaction (PCR) assays to detect and specifically identify L. monocytogenes. Each gene of the pVGC was specifically amplified in L. monocytogenes but not in other Listeria species.

Research paper thumbnail of CaFe 4 As 3 : A Metallic Iron Arsenide with Anisotropic Magnetic and Charge-Transport Properties

Journal of the American Chemical Society, 2009

Research paper thumbnail of Symmetry measurements of the order parameter of BaFe2As2 superconductors

Since the discovery of the Fe-pnictide superconductors, extensive efforts have been directed towa... more Since the discovery of the Fe-pnictide superconductors, extensive efforts have been directed toward understanding the symmetry and mechanism of the superconducting pairing. Extended s-wave models, predominately the s± model, are predicted by many theories, but a definitive experimental verification has been elusive. We are using phase-sensitive Josephson interferometry to test for magnitude and phase anisotropy in electron (Co-doped) and hole (K-doped) BaFe2As2 single crystals. In particular, we are looking in the heavily K-doped regime that is predicted to exhibit d-wave symmetry characterized by a sign change in the order parameter. We are also searching for proximity-induced structure in the density-of-states of an s-wave superconductor proximity-coupled to an Fe-pnictide superconductor that is predicted to arise for s± pairing (Koshelev, 2012).

Research paper thumbnail of Crystal Growth, Structures, and Properties of the Complex Borides, LaOs2Al2B and La2Os2AlB2

Inorganic chemistry, Jan 17, 2015

Single crystals of two novel quaternary metal borides, LaOs2Al2B and La2Os2AlB2, have been grown ... more Single crystals of two novel quaternary metal borides, LaOs2Al2B and La2Os2AlB2, have been grown from La/Ni eutectic fluxes. LaOs2Al2B crystallizes in tetragonal space group P4/mmm with the CeCr2Si2C-type structure, and lattice parameters a = 4.2075(6) Å and c = 5.634(1) Å. La2Os2AlB2 exhibits a new crystal structure in monoclinic space group C2/c with lattice parameters a = 16.629(3) Å, b = 6.048(1) Å, c = 10.393(2) Å, and β = 113.96(3)°. Both structures are three-dimensional frameworks with unusual coordination (for solid-state compounds) of the boron atoms by transition metal atoms. The boron atom is square planar in LaOs2Al2B, whereas it exhibits linear and T-shaped geometries in La2Os2AlB2. Electrical resistivity measurements reveal poor metal behavior (ρ300 K ∼ 900 μΩ cm) for La2Os2AlB2, consistent with the electronic band structure calculations, which also predict a metallic character for LaOs2Al2B.

Research paper thumbnail of In situ studies of a platform for metastable inorganic crystal growth and materials discovery

Proceedings of the National Academy of Sciences of the United States of America, Jan 29, 2014

Rapid shifts in the energy, technological, and environmental demands of materials science call fo... more Rapid shifts in the energy, technological, and environmental demands of materials science call for focused and efficient expansion of the library of functional inorganic compounds. To achieve the requisite efficiency, we need a materials discovery and optimization paradigm that can rapidly reveal all possible compounds for a given reaction and composition space. Here we provide such a paradigm via in situ X-ray diffraction measurements spanning solid, liquid flux, and recrystallization processes. We identify four new ternary sulfides from reactive salt fluxes in a matter of hours, simultaneously revealing routes for ex situ synthesis and crystal growth. Changing the flux chemistry, here accomplished by increasing sulfur content, permits comparison of the allowable crystalline building blocks in each reaction space. The speed and structural information inherent to this method of in situ synthesis provide an experimental complement to computational efforts to predict new compounds and...

Research paper thumbnail of Resonant spin excitation in Ba1-xKxFe2As2

In the iron arsenides, superconductivity occurs when the antiferromagnetism of a parent compound ... more In the iron arsenides, superconductivity occurs when the antiferromagnetism of a parent compound has been suppressed by chemical doping. We have investigated the evolution of the magnetic response with potassium doping in Ba1-xKxFe2As2. In the parent compound (x = 0), there is evidence of a column of inelastic scattering at the AF wavevector, Q = 1.2å-1, consistent with a steep dispersion of gapped spin waves. A similar inelastic column is seen in the normal phase in the x = 0.4 compound, but it persists to lower energy transfer. However, at the superconducting transition of 38K, there is a transfer of spectral weight into an excitation localized at Q = 1.2å-1 and phi = 14meV [A. D. Christianson et al, Nature, in press]. Such resonant spin excitations, which are a universal feature of the copper oxide superconductors and seen in several heavy fermion superconductors, provide evidence that the energy gap has unconventional symmetry, with opposite sign on portions of the Fermi surface...

Research paper thumbnail of Heat capacity jump at <span class="aps-inline-formula"><math><msub><mi>T</mi><mi>c</mi></msub></math></span> and pressure derivatives of superconducting transition temperature in the Ba<span class="aps-inline-formula"><math><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></ma...

Physical Review B, 2013

We present the evolution of the initial (up to ∼10 kbar) hydrostatic pressure dependencies of T c... more We present the evolution of the initial (up to ∼10 kbar) hydrostatic pressure dependencies of T c and of the ambient pressure jump in the heat capacity associated with the superconducting transition as a function of K doping in the Ba 1−x K x Fe 2 As 2 family of iron-based superconductors. The pressure derivatives show a weak but distinct anomaly near x ∼ 0.7. In the same concentration region, C p | Tc deviates from the C p ∝ T 3 scaling found for most BaFe 2 As 2 -based superconductors. These results are consistent with a possible significant modification of the superconducting state, occurring near x ∼ 0.7.

Research paper thumbnail of Unconventional superconductivity in Ba0.6K0.4Fe2As2 from inelastic neutron scattering

Research paper thumbnail of Etching characteristics of photoresist and low-k dielectrics by Ar/O2 ferrite-core inductively coupled plasmas

Microelectronic Engineering, 2008

We have investigated the characteristics of Ar/O 2 plasmas in terms of the photoresist (PR) and l... more We have investigated the characteristics of Ar/O 2 plasmas in terms of the photoresist (PR) and low-k material etching using a ferritecore inductively coupled plasma (ICP) etcher. We found that the O 2 /(O 2 + Ar) gas flow ratio significantly affected the PR etching rate and the PR to low-k material etch selectivity. Fourier transform infrared spectroscopy (FTIR) and HF dipping test indicated that the etching damage to the low-k material decreased with decreasing O 2 /(O 2 + Ar) gas flow ratio.

Research paper thumbnail of Study of SnO2 Nanorods Coated Using the PECVD Technique

Journal of the Korean Physical Society, 2007

Journal of the Korean Physical Society, Vol. 50, No. 4, April 2007, pp. 1085~1089 ... Study of Sn... more Journal of the Korean Physical Society, Vol. 50, No. 4, April 2007, pp. 1085~1089 ... Study of SnO2 Nanorods Coated Using the PECVD Technique ... Hyoun Woo Kim,∗ Seung Hyun Shim, Jong Woo Lee, Dong Yeop Shin, Chang Hyun Wi, Byung Don Yoo and Chongmu ...

Research paper thumbnail of Superconductivity in the Narrow-Gap Semiconductor CsBi 4 Te 6

Journal of the American Chemical Society, 2013

Superconductivity was discovered in the narrow-gap semiconductor CsBi 4 Te 6 . A superconducting ... more Superconductivity was discovered in the narrow-gap semiconductor CsBi 4 Te 6 . A superconducting transition around 4.4 K was observed for p-type samples in temperature-dependent resistivity and magnetic susceptibility data. Stoichiometric CsBi 4 Te 6 is not a superconductor. A remarkably high critical field of ∼10 T was estimated from the field-dependent resistivity data. The strongly anisotropic CsBi 4 Te 6 system is monoclinic and the first member of a larger homologous series Cs 4 [Bi 2n+4 Te 3n+6 ] that exhibits unconventional superconductivity, suggesting that proper doping of the homologous series may create a novel class of superconductors from semiconductors.

Research paper thumbnail of Structure and Thermoelectric Properties of the New Quaternary Bismuth Selenides A1−xM4−xBi11+xSe21 (A=K and Rb and Cs; M=Sn and Pb)—Members of the Grand Homologous Series Km(M6Se8)m(M5+nSe9+n)

Chemistry, 2001

Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepa... more Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepared by direct combination of A2Se, Bi2Se3, Sn (or Pb), and Se at 800 degrees C. The single-crystal structures of K(0.54)Sn(3.54)Bi(11.46)Se21, K(1.46)Pb(3.08)Bi(11.46)Se21, Rb(0.69)Pb(3.69)Bi(11.31)Se21, and Cs(0.65)Pb(3.65)Bi(11.35)Se21 were determined. The compounds A(1-x)M(4-x)Bi(11+x) Se21 crystallize in a new structure type with the monoclinic space group C2/m, in which building units of the Bi2Te3 and NaCl structure type join to give rise to a novel kind of three-dimensional anionic framework with alkali-ion-filled tunnels. The building units are assembled from distorted, edge-sharing (Bi,Sn)Se6 octahedra. Bi and Sn/Pb atoms are disordered over the metal sites of the chalcogenide network, while the alkali site is not fully occupied. A grand homologous series Km(M6Se8)m(M(5+n)Se(9+n)) has been identified of which the compounds A(1-x)M(4-x)Bi(11+x)Se21 are members. We discuss here the crystal structure, charge-transport properties, and very low thermal conductivity of A(1-x)M(4-x)Bi(11+x)Se21.

Research paper thumbnail of Topotactic Redox Chemistry of NaFeAs in Water and Air and Superconducting Behavior with Stoichiometry Change

Chemistry of Materials, 2010

We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na defic... more We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na deficient. The oxidation of NaFeAs progresses differently in water and in air. In water the material oxidizes slowly and slightly retaining the original anti-PbFCl structure. In air NaFeAs oxidizes topotactically quickly and extensively transforming to the ThCrSi structure type. Water acts as a mild oxidizing agent on the FeAs layer by extracting electrons and Na{sup +} cations from the structure, while oxidation in air is more extensive and leads to change in structure type from NaFeAs to NaFeAs. The superconducting transition temperature moves dramatically during the oxidation process. Exposed to water for an extended time period NaFeAs shows a substantial increase in T{sub c} up to 25 K with contraction of unit cell volume. NaFeAs, the air oxidized product, shows T{sub c} of 12 K. We report detailed characterization of the redox chemistry and transformation of NaFeAs in water and air using single crystal and powder X-ray diffraction, magnetization studies, transmission electron microscopy, Moessbauer spectroscopy, pOH and elemental analysis.

Research paper thumbnail of Understanding Nanostructures in Thermoelectric Materials: An Electron Microscopy Study of AgPb 18 SbSe 20 Crystals

Chemistry of Materials, 2010

The characterization and understanding of the presence of nanostructuring in bulk thermoelectric ... more The characterization and understanding of the presence of nanostructuring in bulk thermoelectric materials requires real space atomic level information. We report electron diffraction and high-resolution transmission electron microscopy studies of crystals of the system AgPbSbSe (=18PbSe + AgSbSe) which reveal that this system is nanostructured rather than a solid solution. Nanocrystals of varying sizes are found, endotaxially grown in the

Research paper thumbnail of Selective Substitution of Cr in CaFe 4 As 3 and Its Effect on the Spin Density Wave

Chemistry of Materials, 2010

Single crystals of CaCr{sub 0.84}Fe{sub 3.16}As, a Cr substituted analog of CaFeAs, were grown fr... more Single crystals of CaCr{sub 0.84}Fe{sub 3.16}As, a Cr substituted analog of CaFeAs, were grown from Sn flux and characterized with single crystal neutron diffraction. CaCr{sub 0.84}Fe{sub 3.16}As crystallizes in the orthorhombic space group Pnma with a three-dimensional framework, where Fe, Cr, and As form a covalent channel-like network with Ca{sup 2+} cations residing in the channels. CaCr{sub 0.84}Fe{sub 3.16}As has

Research paper thumbnail of Species-Specific Detection of Listeria monocytogenes Using Polymerase Chain Reaction Assays Targeting the prfA Virulence Gene Cluster

Bioscience, Biotechnology, and Biochemistry, 2009

Sequence comparison of individual genes in the prfA virulence gene cluster (pVGC), a central viru... more Sequence comparison of individual genes in the prfA virulence gene cluster (pVGC), a central virulence gene cluster, from different Listeria species indicated that priming sites within the genes appeared to be specific for Listeria monocytogenes exclusively. Therefore, the pVGC was targeted for polymerase chain reaction (PCR) assays to detect and specifically identify L. monocytogenes. Each gene of the pVGC was specifically amplified in L. monocytogenes but not in other Listeria species.

Research paper thumbnail of CaFe 4 As 3 : A Metallic Iron Arsenide with Anisotropic Magnetic and Charge-Transport Properties

Journal of the American Chemical Society, 2009