Flavio Zanetti | Harvard University (original) (raw)

Papers by Flavio Zanetti

Research paper thumbnail of ?-Linolenic acid production with Thamnidium elegans by solid-state fermentation on apple pomace

Bioresource Technol, 2000

Research paper thumbnail of Die Behandlung des Nasopharynxkarzinoms mit rekombinantem Gamma-Interferon (IFN)*

Research paper thumbnail of On the molar mass of κ-carrageenan in the course of conformational transition from the disordered to the fundamental ordered form

Macromolecules, 1999

... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Depart... more ... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Department of Chemistry, KULeuven, Celestijnenlaan 200F, Heverlee, Belgium. Flavio Zanetti. POLY-tech SCrl, AREA Science Park, Padriciano ...

Research paper thumbnail of Teilaromatische Polyamide: Eine calorimetrische und dynamisch-mechanische Untersuchung

Research paper thumbnail of Comparison of different methods for determination of molecular weight and molecular weight distribution of alginates

Carbohydrate Polymers, 1991

The scope of the present work was to assess and compare different methods to determine molecular ... more The scope of the present work was to assess and compare different methods to determine molecular weight (MW) averages and molecular weight distributions (MWD) of two samples of sodium alginate of different composition. Weight average (~lw) and number average (~In) molecular weights were determined by totally integrated laser light scattering (LLS), both at wide angles' (WA) and at a low angle (LA), and membrane osmometo', respectively. The two alginates were fractionated by preparative and analytical size exclusion chromatography.

Research paper thumbnail of Equilibrium and nonequilibrium association processes of κ-carrageenan in aqueous salt solutions

Macromolecules, 1999

ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carr... more ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carrageenan undergoes an intramolecular conformational transition under suitable conditions from a semiflexible, disordered conformation to a rather rigid, helical one. By varying the parameters controlling the conformational phase diagram (i.e., by increasing the concentration of polymer or that of the supporting electrolyte, or both, or by decreasing temperature), a tertiary structure is manifested, through a progressive increase of the weight-average molar mass (M̄w) as determined by light scattering. This can be very well explained in terms of a reversible association of stretches of such intramolecular helical structures and quantitatively described by a model of “open association” of two or more chains. The association of κ-carrageenan was demonstrated to take place at around room temperature also in the presence of iodide ions, as long as their concentration is ≥0.20 M. In this way the apparent inconsistency of a number of published M̄w results can be reconciled. Additional light-scattering results indicated that the demonstrated thermodynamic tendency to reversible interchain association may lead to an irreversible aggregation of polymer chains if an improper solution preparation procedure is used.

Research paper thumbnail of O uso de redes neurais artificiais como ferramenta para auxiliar na determinação da vida útil de pavimentos flexíveis

Research paper thumbnail of ?-Linolenic acid production by solid-state fermentation of Mucorales strains on cereals

Bioresource Technol, 2001

Research paper thumbnail of Purification and Characterization of Hyaluronan from Synovial Fluid

Analytical Biochemistry

ABSTRACT

Research paper thumbnail of Kinetics of formation of calcium-alginate gels: a rheological study

Research paper thumbnail of Neurodegenerative processes in Huntington's disease

Cell Death and Disease, 2011

Research paper thumbnail of Polyalkylphenyl-sulphonic acid with acid groups of variable strength from compost

The insoluble organic fraction (humin-like material, HLM) from rice hull-dairy cattle compost is ... more The insoluble organic fraction (humin-like material, HLM) from rice hull-dairy cattle compost is well converted into water soluble HLM-sulphonate by reaction in liquid SO3. Microanalytical, potentiometric, molecular weight, and NMR data are consistent with a highly homogeneous polymeric arylsulphonate having 4000 Da MW, 1.3 sulphonic groups per aromatic ring and significant content of carboxylic and phenolic groups. By comparison with structure-property relationships for commercial lignosulphonates derived from the pulp and paper industry, the above arylsulphonate is likely to be a candidate at a variety of applications in the chemical industry and in agriculture. Therefore, sulphonation is a means for upgrading composts HLM to the same uses as for commercial lignosulphonates.

Research paper thumbnail of Fed-batch production and simple isolation of succinoglycan from Agrobacterium tumefaciens

Succinoglycan production by Agrobacterium tumefaciens was increased from 9.5 g/l to 14 g/l when t... more Succinoglycan production by Agrobacterium tumefaciens was increased from 9.5 g/l to 14 g/l when the microorganism was cultivated under fed-batch condition, as compared to batch fermentation. Cells and broth impurities were removed from the fermentation broth with activated charcoal at a temperature of 90 • C, yielding a clear and odorless solution of the polymer. Viscosity mesurement, NMR spectroscopy and Mw determination proved that the polymer retains its main features, practically unaffected by the heat treatment.

Research paper thumbnail of Matrix-assisted laser desorption/ionization mass spectrometry of polysaccharides

Rapid Communications in Mass Spectrometry, 1995

Research paper thumbnail of Determination of Molecular Weight and Molecular Weight Distribution of Agar Fractions Extracted from Gracilaria dura

Research paper thumbnail of On the Molar Mass of κ-Carrageenan in the Course of Conformational Transition from the Disordered to the Fundamental Ordered Form

Macromolecules, 1999

... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Depart... more ... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Department of Chemistry, KULeuven, Celestijnenlaan 200F, Heverlee, Belgium. Flavio Zanetti. POLY-tech SCrl, AREA Science Park, Padriciano ...

Research paper thumbnail of Equilibrium and Nonequilibrium Association Processes of κ-Carrageenan in Aqueous Salt Solutions

Macromolecules, 1999

ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carr... more ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carrageenan undergoes an intramolecular conformational transition under suitable conditions from a semiflexible, disordered conformation to a rather rigid, helical one. By varying the parameters controlling the conformational phase diagram (i.e., by increasing the concentration of polymer or that of the supporting electrolyte, or both, or by decreasing temperature), a tertiary structure is manifested, through a progressive increase of the weight-average molar mass (M̄w) as determined by light scattering. This can be very well explained in terms of a reversible association of stretches of such intramolecular helical structures and quantitatively described by a model of “open association” of two or more chains. The association of κ-carrageenan was demonstrated to take place at around room temperature also in the presence of iodide ions, as long as their concentration is ≥0.20 M. In this way the apparent inconsistency of a number of published M̄w results can be reconciled. Additional light-scattering results indicated that the demonstrated thermodynamic tendency to reversible interchain association may lead to an irreversible aggregation of polymer chains if an improper solution preparation procedure is used.

Research paper thumbnail of Exopolysaccharides produced by Burkholderia cenocepacia recA lineages IIIA and IIIB

Journal of Cystic Fibrosis, 2004

Clinical and environmental strains of Burkholderia cenocepacia belonging to the recA lineages III... more Clinical and environmental strains of Burkholderia cenocepacia belonging to the recA lineages IIIA and IIIB were examined for exopolysaccharide (EPS) production. The exopolysaccharides structure was determined using mainly gas chromatography coupled to mass spectrometry and NMR spectroscopy. All the strains produced Cepacian, a highly branched polysaccharide constituted of a heptasaccharide repeating unit, composed of one rhamnose, one glucose, one glucuronic acid, one mannose and three galactose residues. This polymer is the most common exopolysaccharide produced by strains of the Burkholderia cepacia (Bcc) complex. One clinical strain produced also another polysaccharide constituted of three galactose units and one 3-deoxy-D-manno-2-octulosonic acid residues, a polymer that was previously isolated from two strains of B. cepacia genomovar I and B. cenocepacia IIIA.

Research paper thumbnail of Succinoglycan production by Agrobacterium tumefaciens

Journal of Fermentation and Bioengineering, 1998

A strain of Agrobacterium tumefaciens isolated from soil was cultivated under various conditions ... more A strain of Agrobacterium tumefaciens isolated from soil was cultivated under various conditions in shake flasks to study exopolysaccharides (EPS) production. NMR analysis revealed that the EPS obtained was a succinoglycan-like polymer. Optimal yields of EPS were obtained using sucrose and lysine as the carbon and nitrogen sources, respectively. Supplementation of the medium with various chemicals resulted in a more or less marked effect on the polymer yield and properties: in particular, high phosphate levels and non-ionic surfactants led to the production of polymers of different molecular sixes in yields up to 13.7 g/l. Oxygen availability also affected the polymer yield and quality. The chemical structure was substantially unaffected by the various fermentation conditions tested. A fermentation carried out in a laboratory-scale fermentor yielded 9.6 g/l succinoglycan from 15 g/Z sucrose in the basic medium without further supplements.

Research paper thumbnail of Anticoagulant activity of a proteoglycan in extracts ofCodium fragile ssp.atlanticum

Journal of Applied Phycology, 1990

Aqueous extracts of Codium fragile ssp. atlanticum possess marked anticoagulant activity. The com... more Aqueous extracts of Codium fragile ssp. atlanticum possess marked anticoagulant activity. The compounds responsible appear to be proteoglycans with molecular weights, determined by a low angle, laser light-scattering method, of 1.8 x 106 daltons, with a polydispersity value of 1.2.

Research paper thumbnail of ?-Linolenic acid production with Thamnidium elegans by solid-state fermentation on apple pomace

Bioresource Technol, 2000

Research paper thumbnail of Die Behandlung des Nasopharynxkarzinoms mit rekombinantem Gamma-Interferon (IFN)*

Research paper thumbnail of On the molar mass of κ-carrageenan in the course of conformational transition from the disordered to the fundamental ordered form

Macromolecules, 1999

... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Depart... more ... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Department of Chemistry, KULeuven, Celestijnenlaan 200F, Heverlee, Belgium. Flavio Zanetti. POLY-tech SCrl, AREA Science Park, Padriciano ...

Research paper thumbnail of Teilaromatische Polyamide: Eine calorimetrische und dynamisch-mechanische Untersuchung

Research paper thumbnail of Comparison of different methods for determination of molecular weight and molecular weight distribution of alginates

Carbohydrate Polymers, 1991

The scope of the present work was to assess and compare different methods to determine molecular ... more The scope of the present work was to assess and compare different methods to determine molecular weight (MW) averages and molecular weight distributions (MWD) of two samples of sodium alginate of different composition. Weight average (~lw) and number average (~In) molecular weights were determined by totally integrated laser light scattering (LLS), both at wide angles' (WA) and at a low angle (LA), and membrane osmometo', respectively. The two alginates were fractionated by preparative and analytical size exclusion chromatography.

Research paper thumbnail of Equilibrium and nonequilibrium association processes of κ-carrageenan in aqueous salt solutions

Macromolecules, 1999

ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carr... more ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carrageenan undergoes an intramolecular conformational transition under suitable conditions from a semiflexible, disordered conformation to a rather rigid, helical one. By varying the parameters controlling the conformational phase diagram (i.e., by increasing the concentration of polymer or that of the supporting electrolyte, or both, or by decreasing temperature), a tertiary structure is manifested, through a progressive increase of the weight-average molar mass (M̄w) as determined by light scattering. This can be very well explained in terms of a reversible association of stretches of such intramolecular helical structures and quantitatively described by a model of “open association” of two or more chains. The association of κ-carrageenan was demonstrated to take place at around room temperature also in the presence of iodide ions, as long as their concentration is ≥0.20 M. In this way the apparent inconsistency of a number of published M̄w results can be reconciled. Additional light-scattering results indicated that the demonstrated thermodynamic tendency to reversible interchain association may lead to an irreversible aggregation of polymer chains if an improper solution preparation procedure is used.

Research paper thumbnail of O uso de redes neurais artificiais como ferramenta para auxiliar na determinação da vida útil de pavimentos flexíveis

Research paper thumbnail of ?-Linolenic acid production by solid-state fermentation of Mucorales strains on cereals

Bioresource Technol, 2001

Research paper thumbnail of Purification and Characterization of Hyaluronan from Synovial Fluid

Analytical Biochemistry

ABSTRACT

Research paper thumbnail of Kinetics of formation of calcium-alginate gels: a rheological study

Research paper thumbnail of Neurodegenerative processes in Huntington's disease

Cell Death and Disease, 2011

Research paper thumbnail of Polyalkylphenyl-sulphonic acid with acid groups of variable strength from compost

The insoluble organic fraction (humin-like material, HLM) from rice hull-dairy cattle compost is ... more The insoluble organic fraction (humin-like material, HLM) from rice hull-dairy cattle compost is well converted into water soluble HLM-sulphonate by reaction in liquid SO3. Microanalytical, potentiometric, molecular weight, and NMR data are consistent with a highly homogeneous polymeric arylsulphonate having 4000 Da MW, 1.3 sulphonic groups per aromatic ring and significant content of carboxylic and phenolic groups. By comparison with structure-property relationships for commercial lignosulphonates derived from the pulp and paper industry, the above arylsulphonate is likely to be a candidate at a variety of applications in the chemical industry and in agriculture. Therefore, sulphonation is a means for upgrading composts HLM to the same uses as for commercial lignosulphonates.

Research paper thumbnail of Fed-batch production and simple isolation of succinoglycan from Agrobacterium tumefaciens

Succinoglycan production by Agrobacterium tumefaciens was increased from 9.5 g/l to 14 g/l when t... more Succinoglycan production by Agrobacterium tumefaciens was increased from 9.5 g/l to 14 g/l when the microorganism was cultivated under fed-batch condition, as compared to batch fermentation. Cells and broth impurities were removed from the fermentation broth with activated charcoal at a temperature of 90 • C, yielding a clear and odorless solution of the polymer. Viscosity mesurement, NMR spectroscopy and Mw determination proved that the polymer retains its main features, practically unaffected by the heat treatment.

Research paper thumbnail of Matrix-assisted laser desorption/ionization mass spectrometry of polysaccharides

Rapid Communications in Mass Spectrometry, 1995

Research paper thumbnail of Determination of Molecular Weight and Molecular Weight Distribution of Agar Fractions Extracted from Gracilaria dura

Research paper thumbnail of On the Molar Mass of κ-Carrageenan in the Course of Conformational Transition from the Disordered to the Fundamental Ordered Form

Macromolecules, 1999

... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Depart... more ... Karin Bongaerts and Harry Reynaers. Laboratory of Macromolecular Structural Chemistry, Department of Chemistry, KULeuven, Celestijnenlaan 200F, Heverlee, Belgium. Flavio Zanetti. POLY-tech SCrl, AREA Science Park, Padriciano ...

Research paper thumbnail of Equilibrium and Nonequilibrium Association Processes of κ-Carrageenan in Aqueous Salt Solutions

Macromolecules, 1999

ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carr... more ABSTRACT A large number of light-scattering data indicate that the sulfated polysaccharide κ-carrageenan undergoes an intramolecular conformational transition under suitable conditions from a semiflexible, disordered conformation to a rather rigid, helical one. By varying the parameters controlling the conformational phase diagram (i.e., by increasing the concentration of polymer or that of the supporting electrolyte, or both, or by decreasing temperature), a tertiary structure is manifested, through a progressive increase of the weight-average molar mass (M̄w) as determined by light scattering. This can be very well explained in terms of a reversible association of stretches of such intramolecular helical structures and quantitatively described by a model of “open association” of two or more chains. The association of κ-carrageenan was demonstrated to take place at around room temperature also in the presence of iodide ions, as long as their concentration is ≥0.20 M. In this way the apparent inconsistency of a number of published M̄w results can be reconciled. Additional light-scattering results indicated that the demonstrated thermodynamic tendency to reversible interchain association may lead to an irreversible aggregation of polymer chains if an improper solution preparation procedure is used.

Research paper thumbnail of Exopolysaccharides produced by Burkholderia cenocepacia recA lineages IIIA and IIIB

Journal of Cystic Fibrosis, 2004

Clinical and environmental strains of Burkholderia cenocepacia belonging to the recA lineages III... more Clinical and environmental strains of Burkholderia cenocepacia belonging to the recA lineages IIIA and IIIB were examined for exopolysaccharide (EPS) production. The exopolysaccharides structure was determined using mainly gas chromatography coupled to mass spectrometry and NMR spectroscopy. All the strains produced Cepacian, a highly branched polysaccharide constituted of a heptasaccharide repeating unit, composed of one rhamnose, one glucose, one glucuronic acid, one mannose and three galactose residues. This polymer is the most common exopolysaccharide produced by strains of the Burkholderia cepacia (Bcc) complex. One clinical strain produced also another polysaccharide constituted of three galactose units and one 3-deoxy-D-manno-2-octulosonic acid residues, a polymer that was previously isolated from two strains of B. cepacia genomovar I and B. cenocepacia IIIA.

Research paper thumbnail of Succinoglycan production by Agrobacterium tumefaciens

Journal of Fermentation and Bioengineering, 1998

A strain of Agrobacterium tumefaciens isolated from soil was cultivated under various conditions ... more A strain of Agrobacterium tumefaciens isolated from soil was cultivated under various conditions in shake flasks to study exopolysaccharides (EPS) production. NMR analysis revealed that the EPS obtained was a succinoglycan-like polymer. Optimal yields of EPS were obtained using sucrose and lysine as the carbon and nitrogen sources, respectively. Supplementation of the medium with various chemicals resulted in a more or less marked effect on the polymer yield and properties: in particular, high phosphate levels and non-ionic surfactants led to the production of polymers of different molecular sixes in yields up to 13.7 g/l. Oxygen availability also affected the polymer yield and quality. The chemical structure was substantially unaffected by the various fermentation conditions tested. A fermentation carried out in a laboratory-scale fermentor yielded 9.6 g/l succinoglycan from 15 g/Z sucrose in the basic medium without further supplements.

Research paper thumbnail of Anticoagulant activity of a proteoglycan in extracts ofCodium fragile ssp.atlanticum

Journal of Applied Phycology, 1990

Aqueous extracts of Codium fragile ssp. atlanticum possess marked anticoagulant activity. The com... more Aqueous extracts of Codium fragile ssp. atlanticum possess marked anticoagulant activity. The compounds responsible appear to be proteoglycans with molecular weights, determined by a low angle, laser light-scattering method, of 1.8 x 106 daltons, with a polydispersity value of 1.2.