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Papers by Cees Van der Marel

Research paper thumbnail of Synthesis and Characterization of Methacrylic Derivatives of 5-Amino Salicylic Acid with pH-Sensitive Swelling Properties

AAPS PharmSciTech, 2001

The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensit... more The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensitive swelling and drug release properties. Methacrylic-type polymeric prodrugs with different content levels of 5-amino salicylic acid (5-ASA) were synthesized by free radical copolymerization of metacrylic acid (MAA), polyethylene glycol monomethacrylate (PEGMA), and a methacrylic derivative of 5-ASA (methacryloyloxyethyl 5-amino salicylate [MOES]). The copolymers were characterized,

Research paper thumbnail of Physical properties of liquid Li-Cd alloys and of the solid compound LiCd

Journal of Physics F: Metal Physics, 1980

ABSTRACT The liquid alloys of Li and Cd, the electrical resistivity and the Knight shift have bee... more ABSTRACT The liquid alloys of Li and Cd, the electrical resistivity and the Knight shift have been measured over the entire concentration range. The resistivities can be explained fairly well within the Ziman diffraction model. The Knight shift versus concentration exhibits a sudden change of slope at the composition Li0.5Cd0.5. NMR linewidth measurements on the solid compound LiCd provided evidence for an appreciable mobility of the Li atoms through the lattice; the corresponding activation energy for diffusion is found to be 0.49+or-0.03 eV.

Research paper thumbnail of Knight shift and electrical resistivity of liquid Li-In alloys

Journal of Physics F: Metal Physics, 1978

ABSTRACT The 115In and 7Li Knight shifts and the electrical resistivities of a number of liquid L... more ABSTRACT The 115In and 7Li Knight shifts and the electrical resistivities of a number of liquid Li-In alloys have been determined experimentally. The possibility of Li3In compound forming is discussed.

Research paper thumbnail of The Thermoelectric Power of Liquid Lithium-Sodium Alloys

Le Journal de Physique Colloques, 1980

14easurements of the thermoelectric power of liquid Li-Na alloys have been performed throughout t... more 14easurements of the thermoelectric power of liquid Li-Na alloys have been performed throughout the entire concentration range and at temperatures up to 400'~. The results are in reasonable agreement with calculations within the diffraction model. In the alloy with critical composition (65 at.% Li), critical effects have been observed in a temperature range up to several degrees above the phase separation temperature.

Research paper thumbnail of Knight Shift and Electrical Resistivity of Some Liquid Lithium Alloys

Le Journal de Physique Colloques, 1980

In liquid binary alloys of Li with Cd, In, Sn and Pb both the Li Knight shift and the electrical ... more In liquid binary alloys of Li with Cd, In, Sn and Pb both the Li Knight shift and the electrical resistivity have been measured as a function of concentration and temperature. Combining the results with existing data on the thermodynamical properties of these alloys it is concluded, that a strong charge transfer occurs from Li to the less electropositive Cd, In, Sn or Pb.

Research paper thumbnail of The electrical resistivity of liquid Li-Sn, Na-Sn and Na-Pb alloys: strong effects of chemical interactions

Journal of Physics F: Metal Physics, 1982

Electrical resistivities of liquid Li-Sn, Na-Sn and Na-Pb alloys have been measured. The resistiv... more Electrical resistivities of liquid Li-Sn, Na-Sn and Na-Pb alloys have been measured. The resistivities exhibit distinct maxima close to 'stoichiometric' compositions: Li4Sn, Na4Sn, Na4Sn3 and Na4Pb. At the same compositions the temperature derivative d rho /dT is negative and -d rho /dT assumes extraordinarily large values. The effects are attributed to strong chemical interactions between the components. These interactions tend

Research paper thumbnail of Highly improve photochemical and thermal stability of quantum dots by growing a core-in-matrix hetero-structure

2013 10th China International Forum on Solid State Lighting (ChinaSSL), 2013

Research paper thumbnail of Physical Measurements on Liquid Lithium Alloys

Material Behavior and Physical Chemistry in Liquid Metal Systems, 1982

Research paper thumbnail of Electronic and structural properties of some compound-forming alkali-based alloys

Research paper thumbnail of Inelastic neutron scattering studies of molten NaCs alloys

Journal of Physics F: Metal Physics, 1987

ABSTRACT The authors have measured inelastic neutron scattering spectra of molten Na0.5Cs0.5 and ... more ABSTRACT The authors have measured inelastic neutron scattering spectra of molten Na0.5Cs0.5 and Na0.85Cs0.15 alloys using the time-of-flight spectrometer IN6 at the Institut Laue-Langevin. The composition Na0.85Cs0.15 corresponds to the maximum value of Scc(Q to 0) indicating a tendency to phase separation. The width of the total dynamical structure factor ST(Q, omega ) at low Q is significantly larger for Na0.85Cs0.15 than for Na0.5Cs0.5. Quasi-dispersion curves derived from peak positions of the total longitudinal current power spectra show a single (overdamped) 'Na-like' mode for Na0.85Cs0.15 and both 'Na-like' and 'Cs-like' modes for Na0.5Cs0.5. Appropriate dynamical variables in this Q range for these alloys are therefore atom type. No evidence of propagating acoustic modes is found in the (Q, omega ) range studied.

Research paper thumbnail of 7 Li Knight shift of liquid Li-Pb and Li-Sn alloys

Journal of Physics F: Metal Physics, 1980

ABSTRACT The 7Li Knight shift has been measured in liquid Li-Pb and Li-Sn alloys through the enti... more ABSTRACT The 7Li Knight shift has been measured in liquid Li-Pb and Li-Sn alloys through the entire concentration range and at several temperatures. The Knight shifts in liquid Li-Pb are discussed together with the electrical conductivity and the spin-lattice relaxation time T1, which also exhibit anomalous behaviour near the composition Li4Pb. The results support the assumption of a partially salt-like mixture around the composition Li4Pb.

Research paper thumbnail of The 7 Li Knight shift of liquid Li-Ge alloys

Journal of Physics F: Metal Physics, 1982

ABSTRACT The 7Li Knight shift in liquid lithium-germanium alloys has been measured through the ma... more ABSTRACT The 7Li Knight shift in liquid lithium-germanium alloys has been measured through the main part of the composition range. The results, particularly those obtained close to the liquidus, indicate both charge transfer and the formation of homopolar compounds in the liquid.

Research paper thumbnail of Electrical Resistivity and Phase Separation in Dilute Liquid Alloys of Sodium in Selenium

Zeitschrift für Naturforschung A, 1979

ABSTRACT

Research paper thumbnail of 7Li Knight shift in liquid Li-Mg alloys

Physica B+C, 1982

ABSTRACT

Research paper thumbnail of Thermoelectric power of liquid Li-Na alloys

Physical Review B, 1980

ABSTRACT

Research paper thumbnail of The phase diagram of the system lithium-silicon

Solid State Communications, 1985

Research paper thumbnail of The electrical resistivity of liquid potassium-rubidium, rubidium-caesium and sodium-potassium alloys

Research paper thumbnail of Wie sauber ist der Siliciumwafer?

Nachrichten aus der Chemie, 2010

Research paper thumbnail of X-ray diffraction measurements on liquid iodine and some dilute mixtures of KI in I 2

Molecular Physics, 1988

ABSTRACT Using X-ray diffraction we have determined the structure factor of pure iodine and of a ... more ABSTRACT Using X-ray diffraction we have determined the structure factor of pure iodine and of a number of dilute mixtures of KI in I2. We show that these liquids exhibit short-range orientational order, adjacent molecules being orient- ed more or less parallel. The intramolecular bond length in pure liquid iodine is 2·70±0·01 Å, intermediate between the bond lengths of gaseous and solid iodine. Upon addition of KI the bond length increases, while the distances to atoms in the second and third shell decrease. These effects are related to recent high-pressure diffraction measurements on solid iodine.

Research paper thumbnail of Anomalous magnetic field dependence of the nuclear spin-lattice relaxation in liquid lithium-silicium alloys

Journal of Physics: Condensed Matter, 1995

ABSTRACT Accurate measurements of the nuclear spin-lattice relaxation rate (1/T1) of 8Li nuclei i... more ABSTRACT Accurate measurements of the nuclear spin-lattice relaxation rate (1/T1) of 8Li nuclei in liquid LixSi1-x have been performed as a function of temperature (T) and magnetic field (B) for various compositions using the beta -NMR method. The results show clearly that the magnetic field dependence of T1 follows a square root B law around the x=0.5 composition. We interpret this as an indication for anomalous diffusion of electrons due to strong disorder. From the coefficient of the square root B contribution to 1/T1 we derive that the partial Li s density of states at the Fermi level is about 1/10 of the total density of states at the Fermi level. This is the first observation of such a magnetic field dependence of 1/T1.

Research paper thumbnail of Synthesis and Characterization of Methacrylic Derivatives of 5-Amino Salicylic Acid with pH-Sensitive Swelling Properties

AAPS PharmSciTech, 2001

The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensit... more The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensitive swelling and drug release properties. Methacrylic-type polymeric prodrugs with different content levels of 5-amino salicylic acid (5-ASA) were synthesized by free radical copolymerization of metacrylic acid (MAA), polyethylene glycol monomethacrylate (PEGMA), and a methacrylic derivative of 5-ASA (methacryloyloxyethyl 5-amino salicylate [MOES]). The copolymers were characterized,

Research paper thumbnail of Physical properties of liquid Li-Cd alloys and of the solid compound LiCd

Journal of Physics F: Metal Physics, 1980

ABSTRACT The liquid alloys of Li and Cd, the electrical resistivity and the Knight shift have bee... more ABSTRACT The liquid alloys of Li and Cd, the electrical resistivity and the Knight shift have been measured over the entire concentration range. The resistivities can be explained fairly well within the Ziman diffraction model. The Knight shift versus concentration exhibits a sudden change of slope at the composition Li0.5Cd0.5. NMR linewidth measurements on the solid compound LiCd provided evidence for an appreciable mobility of the Li atoms through the lattice; the corresponding activation energy for diffusion is found to be 0.49+or-0.03 eV.

Research paper thumbnail of Knight shift and electrical resistivity of liquid Li-In alloys

Journal of Physics F: Metal Physics, 1978

ABSTRACT The 115In and 7Li Knight shifts and the electrical resistivities of a number of liquid L... more ABSTRACT The 115In and 7Li Knight shifts and the electrical resistivities of a number of liquid Li-In alloys have been determined experimentally. The possibility of Li3In compound forming is discussed.

Research paper thumbnail of The Thermoelectric Power of Liquid Lithium-Sodium Alloys

Le Journal de Physique Colloques, 1980

14easurements of the thermoelectric power of liquid Li-Na alloys have been performed throughout t... more 14easurements of the thermoelectric power of liquid Li-Na alloys have been performed throughout the entire concentration range and at temperatures up to 400'~. The results are in reasonable agreement with calculations within the diffraction model. In the alloy with critical composition (65 at.% Li), critical effects have been observed in a temperature range up to several degrees above the phase separation temperature.

Research paper thumbnail of Knight Shift and Electrical Resistivity of Some Liquid Lithium Alloys

Le Journal de Physique Colloques, 1980

In liquid binary alloys of Li with Cd, In, Sn and Pb both the Li Knight shift and the electrical ... more In liquid binary alloys of Li with Cd, In, Sn and Pb both the Li Knight shift and the electrical resistivity have been measured as a function of concentration and temperature. Combining the results with existing data on the thermodynamical properties of these alloys it is concluded, that a strong charge transfer occurs from Li to the less electropositive Cd, In, Sn or Pb.

Research paper thumbnail of The electrical resistivity of liquid Li-Sn, Na-Sn and Na-Pb alloys: strong effects of chemical interactions

Journal of Physics F: Metal Physics, 1982

Electrical resistivities of liquid Li-Sn, Na-Sn and Na-Pb alloys have been measured. The resistiv... more Electrical resistivities of liquid Li-Sn, Na-Sn and Na-Pb alloys have been measured. The resistivities exhibit distinct maxima close to 'stoichiometric' compositions: Li4Sn, Na4Sn, Na4Sn3 and Na4Pb. At the same compositions the temperature derivative d rho /dT is negative and -d rho /dT assumes extraordinarily large values. The effects are attributed to strong chemical interactions between the components. These interactions tend

Research paper thumbnail of Highly improve photochemical and thermal stability of quantum dots by growing a core-in-matrix hetero-structure

2013 10th China International Forum on Solid State Lighting (ChinaSSL), 2013

Research paper thumbnail of Physical Measurements on Liquid Lithium Alloys

Material Behavior and Physical Chemistry in Liquid Metal Systems, 1982

Research paper thumbnail of Electronic and structural properties of some compound-forming alkali-based alloys

Research paper thumbnail of Inelastic neutron scattering studies of molten NaCs alloys

Journal of Physics F: Metal Physics, 1987

ABSTRACT The authors have measured inelastic neutron scattering spectra of molten Na0.5Cs0.5 and ... more ABSTRACT The authors have measured inelastic neutron scattering spectra of molten Na0.5Cs0.5 and Na0.85Cs0.15 alloys using the time-of-flight spectrometer IN6 at the Institut Laue-Langevin. The composition Na0.85Cs0.15 corresponds to the maximum value of Scc(Q to 0) indicating a tendency to phase separation. The width of the total dynamical structure factor ST(Q, omega ) at low Q is significantly larger for Na0.85Cs0.15 than for Na0.5Cs0.5. Quasi-dispersion curves derived from peak positions of the total longitudinal current power spectra show a single (overdamped) 'Na-like' mode for Na0.85Cs0.15 and both 'Na-like' and 'Cs-like' modes for Na0.5Cs0.5. Appropriate dynamical variables in this Q range for these alloys are therefore atom type. No evidence of propagating acoustic modes is found in the (Q, omega ) range studied.

Research paper thumbnail of 7 Li Knight shift of liquid Li-Pb and Li-Sn alloys

Journal of Physics F: Metal Physics, 1980

ABSTRACT The 7Li Knight shift has been measured in liquid Li-Pb and Li-Sn alloys through the enti... more ABSTRACT The 7Li Knight shift has been measured in liquid Li-Pb and Li-Sn alloys through the entire concentration range and at several temperatures. The Knight shifts in liquid Li-Pb are discussed together with the electrical conductivity and the spin-lattice relaxation time T1, which also exhibit anomalous behaviour near the composition Li4Pb. The results support the assumption of a partially salt-like mixture around the composition Li4Pb.

Research paper thumbnail of The 7 Li Knight shift of liquid Li-Ge alloys

Journal of Physics F: Metal Physics, 1982

ABSTRACT The 7Li Knight shift in liquid lithium-germanium alloys has been measured through the ma... more ABSTRACT The 7Li Knight shift in liquid lithium-germanium alloys has been measured through the main part of the composition range. The results, particularly those obtained close to the liquidus, indicate both charge transfer and the formation of homopolar compounds in the liquid.

Research paper thumbnail of Electrical Resistivity and Phase Separation in Dilute Liquid Alloys of Sodium in Selenium

Zeitschrift für Naturforschung A, 1979

ABSTRACT

Research paper thumbnail of 7Li Knight shift in liquid Li-Mg alloys

Physica B+C, 1982

ABSTRACT

Research paper thumbnail of Thermoelectric power of liquid Li-Na alloys

Physical Review B, 1980

ABSTRACT

Research paper thumbnail of The phase diagram of the system lithium-silicon

Solid State Communications, 1985

Research paper thumbnail of The electrical resistivity of liquid potassium-rubidium, rubidium-caesium and sodium-potassium alloys

Research paper thumbnail of Wie sauber ist der Siliciumwafer?

Nachrichten aus der Chemie, 2010

Research paper thumbnail of X-ray diffraction measurements on liquid iodine and some dilute mixtures of KI in I 2

Molecular Physics, 1988

ABSTRACT Using X-ray diffraction we have determined the structure factor of pure iodine and of a ... more ABSTRACT Using X-ray diffraction we have determined the structure factor of pure iodine and of a number of dilute mixtures of KI in I2. We show that these liquids exhibit short-range orientational order, adjacent molecules being orient- ed more or less parallel. The intramolecular bond length in pure liquid iodine is 2·70±0·01 Å, intermediate between the bond lengths of gaseous and solid iodine. Upon addition of KI the bond length increases, while the distances to atoms in the second and third shell decrease. These effects are related to recent high-pressure diffraction measurements on solid iodine.

Research paper thumbnail of Anomalous magnetic field dependence of the nuclear spin-lattice relaxation in liquid lithium-silicium alloys

Journal of Physics: Condensed Matter, 1995

ABSTRACT Accurate measurements of the nuclear spin-lattice relaxation rate (1/T1) of 8Li nuclei i... more ABSTRACT Accurate measurements of the nuclear spin-lattice relaxation rate (1/T1) of 8Li nuclei in liquid LixSi1-x have been performed as a function of temperature (T) and magnetic field (B) for various compositions using the beta -NMR method. The results show clearly that the magnetic field dependence of T1 follows a square root B law around the x=0.5 composition. We interpret this as an indication for anomalous diffusion of electrons due to strong disorder. From the coefficient of the square root B contribution to 1/T1 we derive that the partial Li s density of states at the Fermi level is about 1/10 of the total density of states at the Fermi level. This is the first observation of such a magnetic field dependence of 1/T1.