Boris Chornik | Universidad de Chile (original) (raw)
Papers by Boris Chornik
Molecules, 2016
Cyclodextrin (CD) molecules form inclusion compounds (ICs), generating dimers that are capable of... more Cyclodextrin (CD) molecules form inclusion compounds (ICs), generating dimers that are capable of encapsulating molecules derived from long-chain hydrocarbons. The aim of this study is to evaluate the structural changes experienced by ICs in solution with increasing temperatures. For this, a nuclear magnetic resonance (1 H-NMR) titration was performed to determinate the stoichiometric α-cyclodextrin (α-CD):octylamine (OA) 2:1 and binding constant (k = 2.16 M −2) of ICs. Solution samples of α-CD-OA ICs conjugated with gold nanoparticles (AuNPs) were prepared, and 1 H-NMR spectra at different temperatures were recorded. Comparatively, 1 H-NMR spectra of the sample irradiated with a laser with tunable wavelengths, with plasmons of conjugated AuNPs, were recorded. In this work, we present evidence of the disassembly of ICs conjugated with AuNPs. Thermal studies demonstrated that, at 114 • C, there are reversible rearrangements of the host and guests in the ICs in a solid state. Migration movements of the guest molecules from the CD cavity were monitored via temperature-dependent 1 H-NMR, and were verified comparing the chemical shifts of octylamine dissolved in deuterated dimethylsulfoxide (DMSO-d 6) with the OA molecule included in α-CD dissolved in the same solvent. It was observed that, at 117 • C, OA exited the α-CD cavity. CD IC dimer disassembly was also observed when the sample was irradiated with green laser light.
Surface Mobilities on Solid Materials, 1983
The influence of interactions between adsorbed particles on their diffusion constant is investiga... more The influence of interactions between adsorbed particles on their diffusion constant is investigated by kinetic Ising models with independent nearest neighbour hops. This leads to expressions for the ratio of the diffusion constant at arbitrary coverage θ to its value at θ = 0 as a function of the interaction energies relative to temperature. It is shown that under certain conditions this quantity obeys a particle-hole symmetry. Exact results in the whole range of densities are given in one dimension for nearest neighbour interaction. They already yield a qualitative agreement with experimental results and are also compared to corresponding numerical simulations. The introduction of a next nearest neighbour interaction is shown to produce drastic changes in the density dependence of the diffusion constant in some of the cases. A generalized quasichemical approximation and a virial expansion are made in two dimensions, leading to a better agreement with the measurements.
Journal of Non-Crystalline Solids, 2014
Amorphous non-stoichiometric molybdenum oxide thin films have been successfully prepared by direc... more Amorphous non-stoichiometric molybdenum oxide thin films have been successfully prepared by direct UV irradiation of amorphous films of molybdenum dioxo tropolonate complexes on Si(100) substrates. Photodeposited films were characterized by X-ray photoelectron spectroscopy (XPS) and the surface morphology examined by Atomic Force Microscopy (AFM). It was found that as-photodeposited films are uniform with rms surface roughness of 231 nm and contain non-stoichiometric oxides (MoO 3 − x). The results of XRD analysis showed that postannealing of the films in air at 350°C transforms the sub-oxides to α-MoO 3 phase with a much smoother surface morphology (rms = 164 nm). Both, the as-photodeposited and annealed MoO 3 − x films exhibit good optical quality with transparency in the visible region better than 80%. Gas sensing tests reveal that annealed MoO 3 − x films exhibit a better response than as-deposited films towards 50 ppm ammonia at an operating temperature of 350°C.
Journal of Nanoscience and Nanotechnology
Nanomaterials
The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX)... more The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX) as a guest molecule was obtained to increase the solubility of MTX and decrease its inherent toxic effects in nonspecific cells. The IC was conjugated with gold nanoparticles (AuNPs), obtained by a chemical method, creating a ternary intelligent delivery system for MTX molecules, based on the plasmonic properties of the AuNPs. Irradiation of the ternary system, with a laser wavelength tunable with the corresponding surface plasmon of AuNPs, causes local energy dissipation, producing the controlled release of the guest from CD cavities. Finally, cell viability was evaluated using MTS assays for β-CD/MTX and AuNPs + β-CD/MTX samples, with and without irradiation, against HeLa tumor cells. The irradiated sample of the ternary system AuNPs + β-CD/MTX produced a diminution in cell viability attributed to the photothermal release of MTX.
Nanomaterials
The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX)... more The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX) as a guest molecule was obtained to increase the solubility of MTX and decrease its inherent toxic effects in nonspecific cells. The IC was conjugated with gold nanoparticles (AuNPs), obtained by a chemical method, creating a ternary intelligent delivery system for MTX molecules, based on the plasmonic properties of the AuNPs. Irradiation of the ternary system, with a laser wavelength tunable with the corresponding surface plasmon of AuNPs, causes local energy dissipation, producing the controlled release of the guest from CD cavities. Finally, cell viability was evaluated using MTS assays for β-CD/MTX and AuNPs + β-CD/MTX samples, with and without irradiation, against HeLa tumor cells. The irradiated sample of the ternary system AuNPs + β-CD/MTX produced a diminution in cell viability attributed to the photothermal release of MTX.
Applied Catalysis A: General, 2009
... In order to accurately determine the BE of the different element core levels, high resolution... more ... In order to accurately determine the BE of the different element core levels, high resolution spectra were always fitted using GaussianLorentzian curves. Prior to curve fitting, a background was subtracted by the method devised by Shirley [22]. ...
Journal of Physics F: Metal Physics, 1976
ABSTRACT A reinterpretation of nuclear relaxation data on a dilute ferromagnetic Ni0.98Pd0.02 all... more ABSTRACT A reinterpretation of nuclear relaxation data on a dilute ferromagnetic Ni0.98Pd0.02 alloy is made in the light of multiple scattering theory and the coherent potential approximation. The resultant value of the magnetic moment on the Pd site is higher than previous estimates using rigid band theory.
Scripta Metallurgica, 1981
... This e and aluminum is he same intensity. and KL 2 3 he following two po Burkstrand (14) , t ... more ... This e and aluminum is he same intensity. and KL 2 3 he following two po Burkstrand (14) , t g (a fact demons are labeled as I C, D and E wil 1 co II and KI II. ... (IVIC) (January, 1980). 12. K. Kunimori, T. Kawai, T. Kondow, T. Onishi and K. Tamaru, Surf. Sci., 54, 525 (1976). 13. ...
Scripta Metallurgica, 1982
Journal of Scientific Instruments, 1962
Physical Review B, 1971
... tabulates the results of many authors, ranging from 0. 3 to 1. 7 eV, and finally estimates a ... more ... tabulates the results of many authors, ranging from 0. 3 to 1. 7 eV, and finally estimates a splitting of 0. 5* 0. 1 eV in coincidence with Zornberg. ... I am indebted to Professor Leo M. Falicov for very illuminating discussions that led to the inter-pretation of the experimental results. ...
Electrochimica Acta, 2015
Molecules, 2016
Cyclodextrin (CD) molecules form inclusion compounds (ICs), generating dimers that are capable of... more Cyclodextrin (CD) molecules form inclusion compounds (ICs), generating dimers that are capable of encapsulating molecules derived from long-chain hydrocarbons. The aim of this study is to evaluate the structural changes experienced by ICs in solution with increasing temperatures. For this, a nuclear magnetic resonance (1 H-NMR) titration was performed to determinate the stoichiometric α-cyclodextrin (α-CD):octylamine (OA) 2:1 and binding constant (k = 2.16 M −2) of ICs. Solution samples of α-CD-OA ICs conjugated with gold nanoparticles (AuNPs) were prepared, and 1 H-NMR spectra at different temperatures were recorded. Comparatively, 1 H-NMR spectra of the sample irradiated with a laser with tunable wavelengths, with plasmons of conjugated AuNPs, were recorded. In this work, we present evidence of the disassembly of ICs conjugated with AuNPs. Thermal studies demonstrated that, at 114 • C, there are reversible rearrangements of the host and guests in the ICs in a solid state. Migration movements of the guest molecules from the CD cavity were monitored via temperature-dependent 1 H-NMR, and were verified comparing the chemical shifts of octylamine dissolved in deuterated dimethylsulfoxide (DMSO-d 6) with the OA molecule included in α-CD dissolved in the same solvent. It was observed that, at 117 • C, OA exited the α-CD cavity. CD IC dimer disassembly was also observed when the sample was irradiated with green laser light.
Surface Mobilities on Solid Materials, 1983
The influence of interactions between adsorbed particles on their diffusion constant is investiga... more The influence of interactions between adsorbed particles on their diffusion constant is investigated by kinetic Ising models with independent nearest neighbour hops. This leads to expressions for the ratio of the diffusion constant at arbitrary coverage θ to its value at θ = 0 as a function of the interaction energies relative to temperature. It is shown that under certain conditions this quantity obeys a particle-hole symmetry. Exact results in the whole range of densities are given in one dimension for nearest neighbour interaction. They already yield a qualitative agreement with experimental results and are also compared to corresponding numerical simulations. The introduction of a next nearest neighbour interaction is shown to produce drastic changes in the density dependence of the diffusion constant in some of the cases. A generalized quasichemical approximation and a virial expansion are made in two dimensions, leading to a better agreement with the measurements.
Journal of Non-Crystalline Solids, 2014
Amorphous non-stoichiometric molybdenum oxide thin films have been successfully prepared by direc... more Amorphous non-stoichiometric molybdenum oxide thin films have been successfully prepared by direct UV irradiation of amorphous films of molybdenum dioxo tropolonate complexes on Si(100) substrates. Photodeposited films were characterized by X-ray photoelectron spectroscopy (XPS) and the surface morphology examined by Atomic Force Microscopy (AFM). It was found that as-photodeposited films are uniform with rms surface roughness of 231 nm and contain non-stoichiometric oxides (MoO 3 − x). The results of XRD analysis showed that postannealing of the films in air at 350°C transforms the sub-oxides to α-MoO 3 phase with a much smoother surface morphology (rms = 164 nm). Both, the as-photodeposited and annealed MoO 3 − x films exhibit good optical quality with transparency in the visible region better than 80%. Gas sensing tests reveal that annealed MoO 3 − x films exhibit a better response than as-deposited films towards 50 ppm ammonia at an operating temperature of 350°C.
Journal of Nanoscience and Nanotechnology
Nanomaterials
The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX)... more The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX) as a guest molecule was obtained to increase the solubility of MTX and decrease its inherent toxic effects in nonspecific cells. The IC was conjugated with gold nanoparticles (AuNPs), obtained by a chemical method, creating a ternary intelligent delivery system for MTX molecules, based on the plasmonic properties of the AuNPs. Irradiation of the ternary system, with a laser wavelength tunable with the corresponding surface plasmon of AuNPs, causes local energy dissipation, producing the controlled release of the guest from CD cavities. Finally, cell viability was evaluated using MTS assays for β-CD/MTX and AuNPs + β-CD/MTX samples, with and without irradiation, against HeLa tumor cells. The irradiated sample of the ternary system AuNPs + β-CD/MTX produced a diminution in cell viability attributed to the photothermal release of MTX.
Nanomaterials
The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX)... more The inclusion compound (IC) of cyclodextrin (CD) containing the antitumor drug Methotrexate (MTX) as a guest molecule was obtained to increase the solubility of MTX and decrease its inherent toxic effects in nonspecific cells. The IC was conjugated with gold nanoparticles (AuNPs), obtained by a chemical method, creating a ternary intelligent delivery system for MTX molecules, based on the plasmonic properties of the AuNPs. Irradiation of the ternary system, with a laser wavelength tunable with the corresponding surface plasmon of AuNPs, causes local energy dissipation, producing the controlled release of the guest from CD cavities. Finally, cell viability was evaluated using MTS assays for β-CD/MTX and AuNPs + β-CD/MTX samples, with and without irradiation, against HeLa tumor cells. The irradiated sample of the ternary system AuNPs + β-CD/MTX produced a diminution in cell viability attributed to the photothermal release of MTX.
Applied Catalysis A: General, 2009
... In order to accurately determine the BE of the different element core levels, high resolution... more ... In order to accurately determine the BE of the different element core levels, high resolution spectra were always fitted using GaussianLorentzian curves. Prior to curve fitting, a background was subtracted by the method devised by Shirley [22]. ...
Journal of Physics F: Metal Physics, 1976
ABSTRACT A reinterpretation of nuclear relaxation data on a dilute ferromagnetic Ni0.98Pd0.02 all... more ABSTRACT A reinterpretation of nuclear relaxation data on a dilute ferromagnetic Ni0.98Pd0.02 alloy is made in the light of multiple scattering theory and the coherent potential approximation. The resultant value of the magnetic moment on the Pd site is higher than previous estimates using rigid band theory.
Scripta Metallurgica, 1981
... This e and aluminum is he same intensity. and KL 2 3 he following two po Burkstrand (14) , t ... more ... This e and aluminum is he same intensity. and KL 2 3 he following two po Burkstrand (14) , t g (a fact demons are labeled as I C, D and E wil 1 co II and KI II. ... (IVIC) (January, 1980). 12. K. Kunimori, T. Kawai, T. Kondow, T. Onishi and K. Tamaru, Surf. Sci., 54, 525 (1976). 13. ...
Scripta Metallurgica, 1982
Journal of Scientific Instruments, 1962
Physical Review B, 1971
... tabulates the results of many authors, ranging from 0. 3 to 1. 7 eV, and finally estimates a ... more ... tabulates the results of many authors, ranging from 0. 3 to 1. 7 eV, and finally estimates a splitting of 0. 5* 0. 1 eV in coincidence with Zornberg. ... I am indebted to Professor Leo M. Falicov for very illuminating discussions that led to the inter-pretation of the experimental results. ...
Electrochimica Acta, 2015