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Showing papers by "Chalmers University of Technology published in 1971"


Journal ArticleDOI
TL;DR: In this paper, the authors measured the angular distribution of photoelectrons ejected from a gold single crystal by 1.25keV X-rays and found that the distributions for photo-electrons from the Au4f levels show strong modulation due to electron-diffraction effects.

97 citations


Journal ArticleDOI
TL;DR: The nature of the two-electron accepting chromophore is discussed in terms of its properties, and these are consistent with the concept that it contains the tw copper ions undectable by electron paramagnetic resonance as a cupric-cupric pair in the oxidized enzyme.
Abstract: 1 Laccase fdrom Rhus vernicifera was titrated under anaerobic conditions using quinol as the reducing substrate, and changes in the optical and electron paramagnetic resonance specta were measured. 2 Titrations of native laccase as well as enzyme in the presence of the inhibitor, fluoride, demonstrated tht four electrons were required to reduce completely the enzyme as determined by the measurements noted above. 3 The titrations of native laccase three different types of electorn-accepting sites in the molecule. Type 1 copper is associated with the strong absorption band at 614 nm and has a potential of 420 mV. Type 2 copper has the lowest potential, 390 mV, and could not be correlated with any of the resolvable absorption bands in the visible spectrum. The absorption band at 330 nm is suggested to arise from a two-electron accepting chromophore wiith an oxidation-reduction standard potential of 460 mV at pH 7.5. 4 In the presence of excess fluoride, the oxidation-reduction potential of some sites was changed with the result that all sites appear to get the same potential. 5 The nature of the two-electron accepting chromophore is discussed in terms of its properties, and these are consistent with the concept that it contains the tw copper ions undectable by electron paramagnetic resonance as a cupric-cupric pair in the oxidized enzyme.

92 citations


Journal ArticleDOI
TL;DR: A mathematical approach, which in conjunction with a recently developed roentgenologic technique allows for a complete analysis of the motion and is possible to express motion in the construction and concept of the helical axis of motion.

89 citations


Journal ArticleDOI
TL;DR: In this article, Hohenberg, Kohn and Sham provide data for the effective potential μxc for ground state properties and for excitation energies the corresponding potential Vxc is obtained from the self energy of an electron gas and numerical data are provided for the construction of Vxc.

73 citations


Journal ArticleDOI
TL;DR: In this paper, photoelectron spectra excited by x radiation are reported for the band-structure part on clean films of the rare-earth metals Nd, Sm, Dy, and Er.
Abstract: Photoelectron spectra excited by x radiation are reported for the band-structure part on clean films of the rare-earth metals Nd, Sm, Dy, and Er. The dominant part of the spectra is due to excitation of $4f$ electrons. The spectra exhibit a complex and extended structure which is interpreted in terms of multiplet splitting of the final state in the photoemission process.

71 citations


Journal ArticleDOI
TL;DR: The nucleation of martensite is studied in defect-free single crystals of iron and iron-nickel over a size range of 0.002-0.2 µm as discussed by the authors.

68 citations


Journal ArticleDOI
TL;DR: The main catalytic reaction suits a pattern that is consistent with a rapid equilibrium random mechanism, and the enzyme seems to contain at least two nucleotide binding sites, one presumably binding to MgATP2− and the other to ADP3−.
Abstract: This paper gives a presentation of ADP and AMP inhibition of phosphoglycerate kinase with MgATP2− and 3-phospho-d-glycerate as substrates at high and low Mg2+ concentrations and pH 7.8. The enzyme seems to contain at least two nucleotide binding sites, one presumably binding to MgATP2− and the other to ADP3−. The ADP3− binding site might bind MgADP1− also. AMP2− competes for the same form of the enzyme, probably the same site, as MgATP2−. ADP3− and MgADP1− are competive inhibitors and AMP2− is a non-competitive inhibitor of 3-P-glycerate. Values of the inhibition constant, Ki, for ADP3− at low Mg2+ level and MgADP1− at high Mg2+ level are 0.2 and 0.02 mM, respectively. The latter value is about ten times less than the expected Michaelis constant for corresponding substrate in the reverse reaction. Ki for AMP is about 2.0 mM at both low and high Mg2+ concentrations but the inhibition is stronger at a high than at a low Mg2+ level, probably caused by conformational and/or other differences of the enzyme at these two metal ion concentrations. The main catalytic reaction suits a pattern that is consistent with a rapid equilibrium random mechanism.

51 citations


Journal ArticleDOI
TL;DR: Electron paramagnetic resonance analysis shows that H2O2 added to native fungal laccase binds to one specific Cu2+ of the four copper atoms in the enzyme (the so-called Type 2 or “nonblue” Cu2 +), associated with a new absorption band in the visible and nearultraviolet spectrum of the enzyme.
Abstract: 1 Electron paramagnetic resonance analysis shows that H2O2 added to native fungal laccase binds to one specific Cu2+ of the four copper atoms in the enzyme (the so-called Type 2 or “nonblue” Cu2+). 2 This binding of H2O2 is associated with a new absorption band in the visible and nearultraviolet spectrum of the enzyme with its maximum absorbance at 400 nm. 3 Fluoride bound to Type 2 Cu2+ of the enzyme, as commonly prepared, can easily be removed by dialysis of the reduced enzyme. Presence of H2O2 in this dialysis makes the removal of fluoride faster.

51 citations


Journal ArticleDOI
TL;DR: The stopped-flow technique was utilized to measure the 610 and 340 nm absorbances of human ceruloplasmin during oxidation and reduction reactions, confirming earlier observations that the chromophores giving rise to these absorbances are different electron acceptors.
Abstract: The stopped-flow technique was utilized to measure the 610 and 340 nm absorbances of human ceruloplasmin during oxidation and reduction reactions. The results confirm earlier observations that the chromophores giving rise to these absorbances are different electron acceptors. Under steady state conditions both chromophores were partially reduced which indicates that they participate in the oxidase reaction. Oxidation rates for the 610 and 340 nm chromophores of completely reduced ceruloplasmin were too high to be compatible with the respective steady state absorbances. These results, together with a comparison of the oxidation rates for Type 1 copper of partially and completely reduced protein, showed that the oxidation rate for one chromophore is influenced by the oxidation states of the other and/or the nonchromophoric paramagnetic copper (Type 2). Therefore, the oxidase mechanism appears to involve concerted transfer of electrons from the 610 and 340 nm chromophores and possibly Type 2 copper.

49 citations


Journal ArticleDOI
TL;DR: In this article, momentum distributions and Compton profiles of the conduction electrons in Li and Na are calculated considering effects of orthogonalization of the core electrons, periodic potential, and correlation.
Abstract: The momentum distributions and Compton profiles of the conduction electrons in Li and Na are calculated considering effects of orthogonalization of the core electrons, periodic potential, and correlation. Using the orthogonalized-plane-wave method with parameters from Callaway and electron-gas data from an earlier calculation by Lundqvist, we find that the anisotropy of the Compton profile should be measurable for single crystalline Li but not for Na, and that the results compare well with recent experimental data for polycrystalline Li and Na. There is a slight indication of correlation effects beyond those considered here, but more accurate experimental data are needed for a more decisive conclusion.

48 citations


Journal ArticleDOI
TL;DR: In this paper, the mean stopping cross section of thin carbon foils has been determined for light mass particles with 3 ≦ Z1, ≦ 18. The reported values of Se, are in t 0 good agreement with previously published results.
Abstract: The mean stopping cross section, S, of thin carbon foils has been determined for light mass particles with 3 ≦ Z1, ≦ 18. The dependence of stopping cross section on foil thickness and scattering angle is reported. The energy of the incident ions ranged from 4.5 to 46 ke V. The electronic, Se, and nuclear, Sn, stopping cross sections were deduced from the experimentally determined mean stopping cross section at zero output angle, , by putting where t is the foil thickness. The reported values of Se, are in t 0 good agreement with previously published results. The mean nuclear stopping cross section in the forward direction is found to reach a saturation value in foils thicker than about 8 μg/cm2. The increase of S with scattering angle is parabolic at small scattering angles and linear at large scattering angles. Es wurden die mittleren clektronischen Bremsquerschnitte S dunner Kohlefolien fur Ionen mit 3 ≦ Z1, ≦ 18 bestimmt. Die Beziehungen zwischen Bremsquerschnitt, Foliendicke und Streuwinkel werden angegeben. Die Energie der einfallenden Ionen reichte von 4,5 bis 46 keV. Die elektronischen und nuklcaren Bremsquerschnitte Se bzw. Sn wurden aus dem experimentellen Bremsquerschnitt bestimmt, wobei und t die Foliendicke ist. Dic gefundenen Werte Se, stimmen gut mit denen anderer Arbeiten uberein. Der mittlere nuklcare Bremsqucrschnitt in Vorwartsrichtung erreicht fur Folicn dicker als etwa 8 μg/cm2 einen Sattigungswert. Der Zuwachs von S mit dem Streuwinkel ist parabolisch bei kleinen und linear bei grosen Streuwinlieln.

Journal ArticleDOI
TL;DR: In this article, Zirconium was evaporated under ultra high vacuum conditions onto an atomically clean W(100) surface in a combined low energy electron diffraction and reflection high energy electron diffusion apparatus (LEED/RHEED).

Journal ArticleDOI
TL;DR: In this article, the deformation behavior of powder preforms is characterized by the pressure/strain relationship and by the ratio of lateral to vertical flow, and the density distribution in typical forgings is charted by means of hardness measurements.
Abstract: Observations are reported on plane-strain upsetting, between unlubricated flat punches, of powder preforms of varying density at 1160°C (1435 K). Macroscopic deformation behaviour is characterized by the pressure/strain relationship and by the ratio of lateral to vertical flow. Increased preform porosity affects lateral flow similarly to increased friction in forging of dense material.Densification is studied as a function of strain and pressure. Lower preform density requires not only larger strains but also higher pressures for a given final density.The density distribution in typical forgings is charted by means of hardness measurements. Zones of incomplete densification are revealed where local pressure was reduced by lack of constraint, or where strain was impeded by friction effects.

Journal ArticleDOI
TL;DR: In this paper, anaerobic oxidation-reduction titrations of human ceruloplasmin were performed with ascorbate and NADH as reductants, and three acceptors were apparent from titration curves based on optical absorption and electron paramagnetic resonance (EPR) parameters.
Abstract: Anaerobic oxidation-reduction titrations of human ceruloplasmin were performed with ascorbate and NADH as reductants. Under most conditions examined one electron per copper ion was required to diminish completely the electron paramagnetic resonance (EPR) signals and the 330 and 610 nm optical absorption bands. In sodium phosphate buffer at pH 7.4 the same changes were attained by addition of only 0.5 electron per copper ion. However, one equivalent NADH was oxidized per g-atom of copper indicating that the electron accepting capacity of the protein was unchanged. Three kinds of electron acceptors were apparent from titration curves based on optical absorption and EPR parameters. One acceptor is the “blue” copper which gives the Type 1 EPR signal. The second is the remaining paramagnetic copper, Type 2, and this does not have detectable absorption bands in the visible spectrum. The third is a chromophore with an optical absorption maximum near 330 nm and is probably associated with the diamagnetic copper. A temperature-dependent electron shift caused the 610 nm absorbance of partially reduced ceruloplasmin to decrease when the temperature was lowered. Fluoride ion prevented this shift and brough about marked changes in the titration behavior of the electron acceptors.

Journal ArticleDOI
TL;DR: In this paper, the optical transitions between s, p-conduction bands were found to generate structure which shows considerable variation with emission angle, and the energy spectra obtained at different emission angles from a (111) surface of silver were reported.

Journal ArticleDOI
TL;DR: In this article, photo-emission measurements from cesium-coated Cu, Au and Ni films were obtained for photon energies below 11.2 eV, and the results were discussed with reference to the calculated band structures with particular attention given to the interconduction band transitions in Cu around the L symmetry point.
Abstract: Photoemission measurements from cesium-coated Cu, Au and Ni films obtained for photon energies below 11.2 eV are reported. Spectra from clean noble metals were also measured at 21.2 eV photon energy. It has been possible to reduce the work function of Au and Ni below 2 eV without any appreciable distortion of the photoelectron energy distributions. The spectra from cesiated Cu and Au show several previously unresolved details. The results are discussed with reference to the calculated band structures with particular attention given to the interconduction band transitions in Cu around the L symmetry point.

Journal Article
TL;DR: The intensity of light scattered from nine rabbit corneas was measured as a function of scattering angle and polarization of the incident light beam and the stroma was found to be largely responsible for scattering in the backward direction while the epithelium scattered more strongly in the forward direction.
Abstract: The intensity of light scattered from nine rabbit corneas was measured as a function of scattering angle and polarization of the incident light beam. The stroma was found to be largely responsible for scattering in the backward direction, while the epithelium scattered more strongly in the forward direction. The effect of an epithelial edema was to increase the scattering in the forward direction considerably.

Journal ArticleDOI
TL;DR: In this article, the energy dependence of bound state pion production and the magnitude of the cross-sections were investigated for reactions of the type pA → (A+1)π+ where A and (A + 1) are bound nuclei.

Journal ArticleDOI
TL;DR: This work has measured the ratio of scattered light intensity to incident light intensity in the stroma for 12 rabbit corneas as a function of the wavelength in the range 3900 to 7250 A, in very good agreement with the theoretical prediction.
Abstract: It is well known that the almost lossless transmission of light through normal mammalian corneas, an obvious fact, requires a theoretical explanation. The reason for this is the pronounced scattering one would expect if the spatial arrangement of the large number of long transversely submicroscopic fibrils that exist in the stroma were purely random. In a recent theory it was shown that the high corneal transparency can be quantitatively well explained if the fibril arrangement can be described in terms of distorted lattices. One conclusion of this theory is that the ratio of scattered light intensity to incident light intensity in the stroma should be inversely proportional to the fifth power of the light wavelength. In the present work this ratio has been measured for 12 rabbit corneas as a function of the wavelength in the range 3900 to 7250 A. The results are in very good agreement with the theoretical prediction.

Journal ArticleDOI
TL;DR: In this article, the isotopes 201, 203, 205, and 205Po have been studied, using mass-separated radioactive sources produced at the ISOLDE facility at CERN.

Journal ArticleDOI
TL;DR: In this article, no appreciable fine structure is observed in the proton spectra, which have been measured on isotope-separated samples in on-line experiments at the CERN ISOLDE facility.

Journal ArticleDOI
TL;DR: In this article, an X-ray diffraction determination of the carbide phase strain as a function of the overall strain on the tension side of bent strips was carried out on four WC-Co alloys with Co contents of from 6 to 15 weight percent.

Journal ArticleDOI
TL;DR: In this article, the phonon dispersion curves of cesium bromide have been observed by inelastic neutron scattering in the symmetry directions of the symmetry line $T. The measurements were performed at 80 and 300 K using a three-axis crystal spectrometer.
Abstract: The phonon dispersion curves of cesium bromide have been observed by inelastic neutron scattering in the symmetry directions $\ensuremath{\Delta}$, $\ensuremath{\Sigma}$, and $\ensuremath{\Lambda}$ and along the symmetry line $T$. The measurements were performed at 80 and 300 K using a three-axis crystal spectrometer. The observations have been fitted to various versions of the shell model, and the frequency distribution and the temperature dependence of the Debye temperature have been calculated from the model which gives the best fit to the experimental frequencies.

Journal ArticleDOI
TL;DR: The half-lives of the isotopes 179Hg and 178Hg are 1.09 ± 0.04 s and 0.47 − 0.14 s, respectively.

Journal ArticleDOI
TL;DR: Natural lifetimes of some highly excited levels in the Pb-I spectrum have been measured by the zero field level crossing (Hanle) method and are compared with lifetimes derived from oscillator strengths given in the literature.
Abstract: Natural lifetimes of some highly excited levels in the Pb-I spectrum have been measured by the zero field level crossing (Hanle) method. The levels were reached by optical excitation from the metastable 6p 2 3 P 2 and 6p 2 3 P 1 states, were a considerable population had been created by means of adc discharge in a Pb atomic beam. An atomic beam source producing atoms in metastable states is described. For the lifetimes τ of the investigated levels we find:τ(6p(1/2)6d 3 D 1)=3.74(28) ns,τ(6p(1/2)6d 3 F 2)=25.8(1.3) ns,τ(6p(1/2)6d 3 D 2)=4.17(−31) (−49) ns,τ(6p(1/2)6d 3 F 3)=6.08(26) ns,τ(6p(3/2)7s)3 P 2=5.85(27) ns. These results are compared with lifetimes derived from oscillator strengths given in the literature.

Journal ArticleDOI
TL;DR: In this article, an analysis is made of available spectral data on carbon dioxide, extended with an approximative description of the 15-μm, 10μm and 2μm bands, in the form of a comparison with measured total emissivities.

Journal ArticleDOI
TL;DR: The optical constants of Al have been measured at 198, 298, 404, and 552°K in the phonon energy range 0.6 to 2.5 eV as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, a high resolution spectrometer for use at ultrahigh vacuum conditions has been designed, which is used in studies of low energy electrons (5-20 eV) photoemitted from clean surfaces.
Abstract: A high resolution spectrometer for use at ultrahigh vacuum conditions has been designed. It is used in studies of low energy electrons (5-20 eV) photoemitted from clean surfaces. The analyser is of the hemispherical type with a mean radius of curvature for the electrons of 25 mm. All surfaces seen by the free electrons are made of copper. The electron detector is a channeltron used in the pulse counting mode. The analyser yields a resolution of 30 meV full width at half maximum at 10 eV as tested on water vapour samples. The analyser is rotatable around the sample enabling studies to be made of the angular distribution of the photoemitted electrons. Such curves from copper single crystals are presented.

Journal ArticleDOI
TL;DR: In this article, the electron capture decay of 209At has been studied and the main part of the decay proceeds to a 9/2+ level at 2 312 keV, which is interpreted as a core-excited state.
Abstract: 209Po, with one neutron less and two protons more than 208Pb, has been studied in the electron capture decay of 209At. Most of the observed states below 2 MeV excitation can be interpreted as having dominant components corresponding either to one-neutron-hole states or to the coupling of a p1/2 neutron hole to (h9/2)2J ≠ O configurations. Several M1 and E2 transition rates were measured. These, as well as level energies, generally show good agreement with theory. The main part of the 209At electron capture decay proceeds to a 9/2+ level at 2 312 keV, which is interpreted as a core-excited state.

Journal ArticleDOI
TL;DR: In this paper, the weight increase curves of pure iron specimens cold-worked by abrasion with SiC and 7-μ diamond paste have been registered as a function of pressure and temperature.
Abstract: The weight increase curves of pure iron specimens cold-worked by abrasion with SiC and 7-μ diamond paste have been registered as a function of pressure and temperature. The oxidation rate increases with temperature and pressure when the pressure is raised from 0.02 to 0.2 bar. When the pressure is further increased to 1.02 bar at 500 and 625°C the oxidation rate decreases. This decrease is attributed to an orientation of the oxide grains in the α-Fe2O3 surface.