Christian Beraud | Universidad de Valparaiso (original) (raw)
Papers by Christian Beraud
The Journal of Physical Chemistry, 1996
Two-dimensional (2D) triple-quantum 27Al magic-angle spinning (3Q MAS) NMR spectra of VPI-5 have ... more Two-dimensional (2D) triple-quantum 27Al magic-angle spinning (3Q MAS) NMR spectra of VPI-5 have been recorded in situ at room temperature and 85° C. The results confirm that at 70-80° C VPI-5 undergoes a reversible phase transformation from space group P 63 to P ...
Microporous and Mesoporous Materials, Jun 1, 2004
A novel methodology for characterization and quantification the acidic sites of different accessi... more A novel methodology for characterization and quantification the acidic sites of different accessibility has been developed for dealuminated zeolite catalysts. The method is based on probing the accessibility of acid sites by IR spectroscopy of adsorbed alkylpyridines, followed by the characterization of the non-accessible sites by IR spectroscopy of subsequently adsorbed CO. The gradual increase of the size of alkylpyridine probe molecules in a series of experiments allows a step-by-step characterization of the nature and strength of sites with different accessibility. The approach proposed was tested on the series of small-port mordenites dealuminated up to Si/Al ratios of 11, 12, 14 and 18 and characterized by various techniques including XRD, TPD-NH 3 , nitrogen adsorption-desorption, 1 H MAS NMR and IR spectroscopy. It has been demonstrated that upon dealumination of the small-port MOR, two phenomena related to accessibility occur: (i) the acid sites in the side pockets become accessible for such probe molecules as pyridine due to the partial destruction of side pockets upon dealumination (ii) subsequently, the formation of secondary mesopore system due to further dealumination makes the zeolite crystals completely accessible to relatively bulky molecules such as lutidine, collidine, 2,6-di-tert-butylpyridine.
Solid State Nucl Magn Reson, 1994
Magic-angle spinning (MAS) 51V nuclear magnetic resonance (NMR) spectra of V,O, have been recorde... more Magic-angle spinning (MAS) 51V nuclear magnetic resonance (NMR) spectra of V,O, have been recorded at various fields to evidence the relative effects of the quadrupole interaction and electronic shielding at the nucleus. A refinement of the spectra using theoretical simulations has been performed assuming a simultaneous existence of these two anisotropic interactions. The relative orientation of the principal axes for both tensors has been obtained. The results agree with previous single-crystal studies. Reliability of the results is discussed. A fundamental indetermination of the actual relative tensor orientations remains, owing to the powder nature of the sample.
Molecular Crystals and Liquid Crystals Science and Technology Section a Molecular Crystals and Liquid Crystals, 2002
Data Revues 16310748 00090003 05002328, Feb 14, 2008
ABSTRACT A continuous gas flow magic angle spinning (MAS) NMR probehead has been developed, which... more ABSTRACT A continuous gas flow magic angle spinning (MAS) NMR probehead has been developed, which enables simultaneously the observation of catalytic events occurring on catalyst surfaces and the on-line identification of the gas products in the output using mass spectrometry. The temperature inside the MAS rotor in the probe has been controlled and measured by 207Pb MAS NMR spectroscopy of Pb(NO3)2. The hydrogenation of toluene to methylcyclohexane on Pt/ZrO2–SO4 (sulfated zirconia) has been used to demonstrate the ability of this probe to study heterogeneous reaction in situ in flow conditions (operando). The MAS NMR and mass spectrometry were in good qualitative agreement for the analysis of the reaction products. The reaction performed in parallel under similar conditions on a conventional fixed bed catalytic reactor shows that the reactant diffusion and their interaction with the active sites in the MAS NMR reactor are comparable in both conventional and NMR experiments. To cite this article: V. Sundaramurthy et al., C. R. Chimie 9 (2006).
![Research paper thumbnail of ChemInform Abstract: Characterization of Layered γ-Titanium Phosphate (C 2 H 5 NH 3 ) [Ti(H 1.5 PO 4 )(PO 4 )] 2 ×H 2 O Intercalate: A Combined NMR, Synchrotron XRD, and DFT Calculations Study](https://attachments.academia-assets.com/44875144/thumbnails/1.jpg)
](Cheminform, 2008
Study. -The title compound is hydrothermally synthesized from a 1:10:10 mixture of en (70% H2O so... more Study. -The title compound is hydrothermally synthesized from a 1:10:10 mixture of en (70% H2O solution), H3PO4 (85%), and TiCl4 (autoclave, 185°C, 10 d, >90% yield) and characterized by powder XRD, MAS NMR, and FTIR spectroscopy. It crystallizes in the triclinic space group P1 with Z = 1. The pseudo-three-dimensional structure is built up of anionic titanium phosphate layers, similar to those present in the γ-type titanium phosphate, and ethylammonium cations residing in the interlayer one-dimensional channels. Key to the full elucidation of the structure, particularly the hydrogen bonding networks, is the combination of NMR evidence with theoretical calculations of 1 H NMR chemical shifts using the GIPAW approach. -(MAFRA*, L.; ROCHA, J.; FERNANDEZ, C.; CASTRO, G. R.; GARCIA-GRANDA, S.; ESPINA, A.; KHAINAKOV, S. A.; GARCIA, J. R.; Chem. Mater. 20 (2008) 12, 3944-3953; Dep. Chem., Univ. Aveiro, P-3810 Aveiro, Port.; Eng.) -W. Pewestorf 38-023
Magn Reson Chem, 1999
The advantages and drawbacks of various techniques that utilize multiple quantum magic angle spin... more The advantages and drawbacks of various techniques that utilize multiple quantum magic angle spinning (MQMAS) NMR for studying molecular sieves and related materials are reviewed. The techniques include z-filtered MQMAS with rotor synchronization, MQMAS with cross-polarization and MQMAS with REDOR. Several methods of recovering quantitative intensities in MQMAS spectra are discussed. Examples of applications include studies of various types of aluminophosphate.
Catalysis Today, Jun 1, 2011
Journal of Materials Science Materials in Medicine, Jun 1, 2007
A commercial photopolymerizable resinmodified glass-ionomer (Fuji II LC) was studied using a vari... more A commercial photopolymerizable resinmodified glass-ionomer (Fuji II LC) was studied using a variety of nuclear magnetic resonance (NMR) techniques. 1 H and 19 F stray-field imaging (STRAFI) enabled to follow the acid-base reaction kinetics in self-cured (SC) samples. Gelation and maturation processes with 25 min and 40 h average time constants, respectively, were distinguished. In self-& photo-cured (SPC) samples, two processes were also observed, which occurred with 2 s and 47 s average time constants. 1 H, 27 Al and 29 Si magic angle spinning (MAS) NMR, 13 C cross-polarization (CP)/MAS NMR and 27 Al multiple quanta (MQ)MAS NMR spectroscopy were used to obtain structural information on the glass and cements that were either SC or SPC. The presence of methacrylate groups was identified in the solid component. Unreacted hydroxyl ethylmethacrylate (HEMA) was detected in self-cured cement. Al data showed that approximately 28% and 20% of Al is leached out from glass particles in SC and SPC samples, respectively. The upfield shift detected in Si MAS NMR spectra of the cements is consistent with a decrease in the number of Al species in the second coordination sphere of the silicon structures. Scanning electron microscopy (SEM) showed existence of 3D shrinkage of the cement matrix in photo-cured cements.
Gene Therapy, 2011
A novel class of PEGylated polyacridine peptides was developed that mediate potent stimulated gen... more A novel class of PEGylated polyacridine peptides was developed that mediate potent stimulated gene transfer in the liver of mice. Polyacridine peptides, (Acr-X) n -Cys-polyethylene glycol (PEG), possessing 2-6 repeats of Lys-acridine (Acr) spaced by either Lys, Arg, Leu or Glu, were Cys derivatized with PEG (PEG 5000 kDa ) and evaluated as in vivo gene transfer agents. An optimal peptide of (Acr-Lys) 6 -Cys-PEG was able to bind to plasmid DNA (pGL3) with high affinity by polyintercalation, stabilize DNA from metabolism by DNAse and extend the pharmacokinetic half-life of DNA in the circulation for up to 2 h. A tail vein dose of PEGylated polyacridine peptide pGL3 polyplexes (1 mg in 50 ml), followed by a stimulatory hydrodynamic dose of normal saline at times ranging from 5 to 60 min post-DNA administration, led to a high level of luciferase expression in the liver, equivalent to levels mediated by direct hydrodynamic dosing of 1 mg of pGL3. The results establish the unique properties of PEGylated polyacridine peptides as a new and promising class of gene delivery peptides that facilitate reversible binding to plasmid DNA, protecting it from DNase in vivo resulting in an extended circulatory half-life, and release of transfectioncompetent DNA into the liver to mediate a high-level of gene expression upon hydrodynamic boost.
Blood, Jan 20, 2015
Therapy related osteonecrosis has become a dose-limiting toxicity in the treatment of pediatric a... more Therapy related osteonecrosis has become a dose-limiting toxicity in the treatment of pediatric acute lymphoblastic leukemia (ALL). Prior studies on the genetic determinants of osteonecrosis have focused on patients 10 years and older, leaving the genetic risk factors for the larger group of children younger than 10 years incompletely understood. Here, we perform the first evaluation of genetic risk factors for osteonecrosis in children less than 10 years old. The discovery cohort comprised 82 cases of osteonecrosis and 287 controls treated on Children's Oncology Group (COG) standard-risk ALL protocol AALL0331 (NCT00103285, https://clinicaltrials.gov/ct2/show/NCT00103285), with results tested for replication in 817 children less than 10 years treated on COG high-risk ALL protocol AALL0232 (NCT00075725, https://clinicaltrials.gov/ct2/show/NCT00075725). The top replicated SNPs were located near bone morphogenic protein 7 [BMP7: rs79085477 and rs75161997, P=5.34x10(-8) (OR 15.0) an...
Studies in Surface Science and Catalysis, 2001
Studies in Surface Science and Catalysis, 2001
Studies in Surface Science and Catalysis, 2004
A new infrared spectroscopic technique is presented for the characterisation of the interaction o... more A new infrared spectroscopic technique is presented for the characterisation of the interaction of probe molecules with zeolites. It uses the high time resolution of modern infrared spectrometers (in rapid or step scan mode), and allows to reach dynamic adsorption parameters on the μs timescale. These dynamic properties are used to distinguish the various adsorption sites for probe molecules, the
Studies in Surface Science and Catalysis, 2002
ABSTRACT
Studies in Surface Science and Catalysis, 2002
Studies in Surface Science and Catalysis, 2002
ABSTRACT In the solid-state NMR of inorganic materials, double-resonance (or 1H triple-resonance)... more ABSTRACT In the solid-state NMR of inorganic materials, double-resonance (or 1H triple-resonance) experiments often involve a half-integer quadrupolar nucleus that has the disadvantage of exhibiting second-order anisotropic broadening. However, the introduction of two-dimensional multiple-quantum magic-angle spinning (MQMAS) has been the source of a tremendous improvement in the solid-state NMR of half-integer quadrupolar nuclei. By correlating triple (or higher) quantum with observable single-quantum coherences, Frydman demonstrated that it is possible to remove the second-order quadrupolar interaction leading to high-resolution spectra. Taking advantage of the highly resolved dimension of the experiment, double-resonance schemes such as CP, REDOR, or HETCOR have been proposed to obtain a better insight into the connectivity of solids. The MQMAS method not only produces highly resolved 27Al NMR spectra, making easy the determination of the aluminum coordination, but also allows the extraction of additional parameters such as the quadrupolar coupling constants, the isotropic chemical shifts, and the access to the distribution of these parameters.
Studies in Surface Science and Catalysis, 1993
The Journal of Physical Chemistry, 1996
Two-dimensional (2D) triple-quantum 27Al magic-angle spinning (3Q MAS) NMR spectra of VPI-5 have ... more Two-dimensional (2D) triple-quantum 27Al magic-angle spinning (3Q MAS) NMR spectra of VPI-5 have been recorded in situ at room temperature and 85° C. The results confirm that at 70-80° C VPI-5 undergoes a reversible phase transformation from space group P 63 to P ...
Microporous and Mesoporous Materials, Jun 1, 2004
A novel methodology for characterization and quantification the acidic sites of different accessi... more A novel methodology for characterization and quantification the acidic sites of different accessibility has been developed for dealuminated zeolite catalysts. The method is based on probing the accessibility of acid sites by IR spectroscopy of adsorbed alkylpyridines, followed by the characterization of the non-accessible sites by IR spectroscopy of subsequently adsorbed CO. The gradual increase of the size of alkylpyridine probe molecules in a series of experiments allows a step-by-step characterization of the nature and strength of sites with different accessibility. The approach proposed was tested on the series of small-port mordenites dealuminated up to Si/Al ratios of 11, 12, 14 and 18 and characterized by various techniques including XRD, TPD-NH 3 , nitrogen adsorption-desorption, 1 H MAS NMR and IR spectroscopy. It has been demonstrated that upon dealumination of the small-port MOR, two phenomena related to accessibility occur: (i) the acid sites in the side pockets become accessible for such probe molecules as pyridine due to the partial destruction of side pockets upon dealumination (ii) subsequently, the formation of secondary mesopore system due to further dealumination makes the zeolite crystals completely accessible to relatively bulky molecules such as lutidine, collidine, 2,6-di-tert-butylpyridine.
Solid State Nucl Magn Reson, 1994
Magic-angle spinning (MAS) 51V nuclear magnetic resonance (NMR) spectra of V,O, have been recorde... more Magic-angle spinning (MAS) 51V nuclear magnetic resonance (NMR) spectra of V,O, have been recorded at various fields to evidence the relative effects of the quadrupole interaction and electronic shielding at the nucleus. A refinement of the spectra using theoretical simulations has been performed assuming a simultaneous existence of these two anisotropic interactions. The relative orientation of the principal axes for both tensors has been obtained. The results agree with previous single-crystal studies. Reliability of the results is discussed. A fundamental indetermination of the actual relative tensor orientations remains, owing to the powder nature of the sample.
Molecular Crystals and Liquid Crystals Science and Technology Section a Molecular Crystals and Liquid Crystals, 2002
Data Revues 16310748 00090003 05002328, Feb 14, 2008
ABSTRACT A continuous gas flow magic angle spinning (MAS) NMR probehead has been developed, which... more ABSTRACT A continuous gas flow magic angle spinning (MAS) NMR probehead has been developed, which enables simultaneously the observation of catalytic events occurring on catalyst surfaces and the on-line identification of the gas products in the output using mass spectrometry. The temperature inside the MAS rotor in the probe has been controlled and measured by 207Pb MAS NMR spectroscopy of Pb(NO3)2. The hydrogenation of toluene to methylcyclohexane on Pt/ZrO2–SO4 (sulfated zirconia) has been used to demonstrate the ability of this probe to study heterogeneous reaction in situ in flow conditions (operando). The MAS NMR and mass spectrometry were in good qualitative agreement for the analysis of the reaction products. The reaction performed in parallel under similar conditions on a conventional fixed bed catalytic reactor shows that the reactant diffusion and their interaction with the active sites in the MAS NMR reactor are comparable in both conventional and NMR experiments. To cite this article: V. Sundaramurthy et al., C. R. Chimie 9 (2006).
Cheminform, 2008
Study. -The title compound is hydrothermally synthesized from a 1:10:10 mixture of en (70% H2O so... more Study. -The title compound is hydrothermally synthesized from a 1:10:10 mixture of en (70% H2O solution), H3PO4 (85%), and TiCl4 (autoclave, 185°C, 10 d, >90% yield) and characterized by powder XRD, MAS NMR, and FTIR spectroscopy. It crystallizes in the triclinic space group P1 with Z = 1. The pseudo-three-dimensional structure is built up of anionic titanium phosphate layers, similar to those present in the γ-type titanium phosphate, and ethylammonium cations residing in the interlayer one-dimensional channels. Key to the full elucidation of the structure, particularly the hydrogen bonding networks, is the combination of NMR evidence with theoretical calculations of 1 H NMR chemical shifts using the GIPAW approach. -(MAFRA*, L.; ROCHA, J.; FERNANDEZ, C.; CASTRO, G. R.; GARCIA-GRANDA, S.; ESPINA, A.; KHAINAKOV, S. A.; GARCIA, J. R.; Chem. Mater. 20 (2008) 12, 3944-3953; Dep. Chem., Univ. Aveiro, P-3810 Aveiro, Port.; Eng.) -W. Pewestorf 38-023
Magn Reson Chem, 1999
The advantages and drawbacks of various techniques that utilize multiple quantum magic angle spin... more The advantages and drawbacks of various techniques that utilize multiple quantum magic angle spinning (MQMAS) NMR for studying molecular sieves and related materials are reviewed. The techniques include z-filtered MQMAS with rotor synchronization, MQMAS with cross-polarization and MQMAS with REDOR. Several methods of recovering quantitative intensities in MQMAS spectra are discussed. Examples of applications include studies of various types of aluminophosphate.
Catalysis Today, Jun 1, 2011
Journal of Materials Science Materials in Medicine, Jun 1, 2007
A commercial photopolymerizable resinmodified glass-ionomer (Fuji II LC) was studied using a vari... more A commercial photopolymerizable resinmodified glass-ionomer (Fuji II LC) was studied using a variety of nuclear magnetic resonance (NMR) techniques. 1 H and 19 F stray-field imaging (STRAFI) enabled to follow the acid-base reaction kinetics in self-cured (SC) samples. Gelation and maturation processes with 25 min and 40 h average time constants, respectively, were distinguished. In self-& photo-cured (SPC) samples, two processes were also observed, which occurred with 2 s and 47 s average time constants. 1 H, 27 Al and 29 Si magic angle spinning (MAS) NMR, 13 C cross-polarization (CP)/MAS NMR and 27 Al multiple quanta (MQ)MAS NMR spectroscopy were used to obtain structural information on the glass and cements that were either SC or SPC. The presence of methacrylate groups was identified in the solid component. Unreacted hydroxyl ethylmethacrylate (HEMA) was detected in self-cured cement. Al data showed that approximately 28% and 20% of Al is leached out from glass particles in SC and SPC samples, respectively. The upfield shift detected in Si MAS NMR spectra of the cements is consistent with a decrease in the number of Al species in the second coordination sphere of the silicon structures. Scanning electron microscopy (SEM) showed existence of 3D shrinkage of the cement matrix in photo-cured cements.
Gene Therapy, 2011
A novel class of PEGylated polyacridine peptides was developed that mediate potent stimulated gen... more A novel class of PEGylated polyacridine peptides was developed that mediate potent stimulated gene transfer in the liver of mice. Polyacridine peptides, (Acr-X) n -Cys-polyethylene glycol (PEG), possessing 2-6 repeats of Lys-acridine (Acr) spaced by either Lys, Arg, Leu or Glu, were Cys derivatized with PEG (PEG 5000 kDa ) and evaluated as in vivo gene transfer agents. An optimal peptide of (Acr-Lys) 6 -Cys-PEG was able to bind to plasmid DNA (pGL3) with high affinity by polyintercalation, stabilize DNA from metabolism by DNAse and extend the pharmacokinetic half-life of DNA in the circulation for up to 2 h. A tail vein dose of PEGylated polyacridine peptide pGL3 polyplexes (1 mg in 50 ml), followed by a stimulatory hydrodynamic dose of normal saline at times ranging from 5 to 60 min post-DNA administration, led to a high level of luciferase expression in the liver, equivalent to levels mediated by direct hydrodynamic dosing of 1 mg of pGL3. The results establish the unique properties of PEGylated polyacridine peptides as a new and promising class of gene delivery peptides that facilitate reversible binding to plasmid DNA, protecting it from DNase in vivo resulting in an extended circulatory half-life, and release of transfectioncompetent DNA into the liver to mediate a high-level of gene expression upon hydrodynamic boost.
Blood, Jan 20, 2015
Therapy related osteonecrosis has become a dose-limiting toxicity in the treatment of pediatric a... more Therapy related osteonecrosis has become a dose-limiting toxicity in the treatment of pediatric acute lymphoblastic leukemia (ALL). Prior studies on the genetic determinants of osteonecrosis have focused on patients 10 years and older, leaving the genetic risk factors for the larger group of children younger than 10 years incompletely understood. Here, we perform the first evaluation of genetic risk factors for osteonecrosis in children less than 10 years old. The discovery cohort comprised 82 cases of osteonecrosis and 287 controls treated on Children's Oncology Group (COG) standard-risk ALL protocol AALL0331 (NCT00103285, https://clinicaltrials.gov/ct2/show/NCT00103285), with results tested for replication in 817 children less than 10 years treated on COG high-risk ALL protocol AALL0232 (NCT00075725, https://clinicaltrials.gov/ct2/show/NCT00075725). The top replicated SNPs were located near bone morphogenic protein 7 [BMP7: rs79085477 and rs75161997, P=5.34x10(-8) (OR 15.0) an...
Studies in Surface Science and Catalysis, 2001
Studies in Surface Science and Catalysis, 2001
Studies in Surface Science and Catalysis, 2004
A new infrared spectroscopic technique is presented for the characterisation of the interaction o... more A new infrared spectroscopic technique is presented for the characterisation of the interaction of probe molecules with zeolites. It uses the high time resolution of modern infrared spectrometers (in rapid or step scan mode), and allows to reach dynamic adsorption parameters on the μs timescale. These dynamic properties are used to distinguish the various adsorption sites for probe molecules, the
Studies in Surface Science and Catalysis, 2002
ABSTRACT
Studies in Surface Science and Catalysis, 2002
Studies in Surface Science and Catalysis, 2002
ABSTRACT In the solid-state NMR of inorganic materials, double-resonance (or 1H triple-resonance)... more ABSTRACT In the solid-state NMR of inorganic materials, double-resonance (or 1H triple-resonance) experiments often involve a half-integer quadrupolar nucleus that has the disadvantage of exhibiting second-order anisotropic broadening. However, the introduction of two-dimensional multiple-quantum magic-angle spinning (MQMAS) has been the source of a tremendous improvement in the solid-state NMR of half-integer quadrupolar nuclei. By correlating triple (or higher) quantum with observable single-quantum coherences, Frydman demonstrated that it is possible to remove the second-order quadrupolar interaction leading to high-resolution spectra. Taking advantage of the highly resolved dimension of the experiment, double-resonance schemes such as CP, REDOR, or HETCOR have been proposed to obtain a better insight into the connectivity of solids. The MQMAS method not only produces highly resolved 27Al NMR spectra, making easy the determination of the aluminum coordination, but also allows the extraction of additional parameters such as the quadrupolar coupling constants, the isotropic chemical shifts, and the access to the distribution of these parameters.
Studies in Surface Science and Catalysis, 1993