TY - JOUR TI - Recovery of proteins and other biological compounds using fibrous materials: II. Flocculation by polyelectrolyte addition AU - Chen, LA AU - Carbonell, RG AU - Serad, GA T2 - JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY AB - Polyelectrolytes have been used in wastewater treatment processes to destabilize colloidal suspensions of proteins, cells and other biological compounds, resulting in flocculation. When a solution containing a single model protein, bovine serum albumin (BSA), is treated with a polyelectrolyte, carboxymethyl cellulose (CMC), large and strong flocs are formed, which are easily retained by a 20 µm pore size filter. However, when a mixture of proteins, cells, and fats from an actual wastewater sample is treated in the same manner, smaller and weaker flocs are observed. An adsorption and filtration process for the recovery of valuable biological compounds using cellulose-based fibrous materials has been developed. When used simultaneously with CMC, cellulose acetate and triacetate fibrets (CAF and CTF) resulted in high recovery of biomolecules from solution at very low dosages of both polyelectrolyte and fibrets. CMC interacts with biomolecules by electrostatic interactions and polymer bridging, while CTF/CAF facilitate floc growth by adsorption and bridging of primary particles and by entrapment of small aggregates within their highly fibrillated microstructure. © 1999 Society of Chemical Industry DA - 1999/8// PY - 1999/8// DO - 10.1002/(SICI)1097-4660(199908)74:8<740::AID-JCTB112>3.0.CO;2-1 VL - 74 IS - 8 SP - 740-750 SN - 1097-4660 KW - protein recovery KW - wastewater treatment KW - animal feed KW - flocculation KW - polyelectrolytes KW - fibrous materials KW - cellulose acetate KW - triacetate KW - fibrets ER - TY - JOUR TI - Recovery of proteins and other biological compounds using fibrous materials: I. Adsorption by salt addition AU - Chen, L. A. AU - Carbonell, R. G. AU - Serad, G. A. T2 - Journal of Chemical Technology and Biotechnology AB - An adsorption and filtration process for the recovery of proteins and other biological compounds from aqueous streams has been developed, using cellulose-based fibrous materials. Of the many cellulose derivatives studied, cellulose acetate fibrets (CAF) and cellulose triacetate fibrets (CTF) have been shown to be the most effective. In the presence of salts, they lead to protein adsorption by hydrophobic interactions. Model proteins, such as bovine serum albumin (BSA), have been recovered by incubating these solutions with CTF in the presence of ammonium sulfate, followed by filtration through a 20 µm pore size filter. The amount of salt necessary varies with the protein type, but decreases with increasing temperature and protein concentration. High protein recovery has been obtained from an actual wastewater system at low salt dosages. © 1999 Society of Chemical Industry DA - 1999/// PY - 1999/// DO - 10.1002/(sici)1097-4660(199908)74:8<733::aid-jctb111>3.0.co;2-4 VL - 74 IS - 8 SP - 733-739 ER - TY - JOUR TI - Thermodynamic contribution of nucleoside modifications to yeast tRNA(Phe) anticodon stem loop analogs AU - Agris, P. F. AU - Guenther, R. AU - Sochacka, E. AU - Newman, W. AU - Czerwinska, G. AU - Liu, G. H. AU - Ye, W. P. AU - Malkiewicz, A. T2 - Acta Biochimica Polonica DA - 1999/// PY - 1999/// VL - 46 IS - 1 SP - 163-172 ER - TY - JOUR TI - Removal rates of major and trace components of an organic film using aqueous nonionic surfactant solutions AU - Kabin, JA AU - Saez, AE AU - Grant, CS AU - Carbonell, RG T2 - INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH AB - This work examines the cleaning of organic films composed of a primary component (abietic acid) mixed with trace amounts of a second contaminant (benzoic acid). Films were removed from a rotating disk in the presence of aqueous solutions of two poly(ethylene glycol) alkyl ether surfactants: C12E5 and C16E8. With C12E5 the abietic acid was removed from the disk in three successive cleaning stagessolubilization, shear removal, and rollupwhereas the benzoic acid was almost completely removed during the initial solubilization stage. Also, with C12E5 the results show that the micellar solubilization rate of the trace contaminant is directly proportional to its concentration in the film. The ratio of the molar removal rates of benzoic acid to abietic acid with C12E5 is an order of magnitude greater than the ratio of the mole fractions of the two components in the contaminant film. Solutions of C16E8 removed the abietic acid by only the solubilization and rollup stages. The ratio of the molar removal rates of benzoic acid to abietic acid with C16E8 was equal to the ratio of the mole fractions of the two components in the contaminant film. A mathematical model is proposed to quantify the simultaneous removal of benzoic acid and abietic acid during the micellar solubilization stage. The model takes into account the mass-transfer rate between the film and the bulk solution, as well as the micellization rates at the film/surfactant solution interface. The model adequately represents the experimental data. DA - 1999/3// PY - 1999/3// DO - 10.1021/ie980587e VL - 38 IS - 3 SP - 683-691 SN - 0888-5885 ER - TY - JOUR TI - Experimental models of protein-RNA interaction: Isolation and analyses of tRNA(Phe) and U1 snRNA-binding peptides from bacteriophage display libraries AU - Agris, PF AU - Marchbank, MT AU - Newman, W AU - Guenther, R AU - Ingram, P AU - Swallow, J AU - Mucha, P AU - Szyk, A AU - Rekowski, P AU - Peletskaya, E AU - Deutscher, SL T2 - JOURNAL OF PROTEIN CHEMISTRY DA - 1999/5// PY - 1999/5// DO - 10.1023/A:1020688609121 VL - 18 IS - 4 SP - 425-435 SN - 0277-8033 KW - phage peptide display library KW - peptide-RNA binding KW - tRNA KW - U1 snRNA ER - TY - JOUR TI - Supercritical CO2 as a solvent for polymeric stone protective materials AU - Henon, FE AU - Camaiti, M AU - Burke, ALC AU - Carbonell, RG AU - DeSimone, JM AU - Piacenti, F T2 - JOURNAL OF SUPERCRITICAL FLUIDS AB - The utilization of CO2 as a potential solvent for fluoropolymers used for the protection of civil infrastructures (buildings, bridges, monuments, etc.) is of major environmental as well as economic importance. The cloud points of six perfluoropolyethers at different weight concentrations in CO2 have been measured over a wide range of pressures. The results show that these fluorinated polymers are readily soluble in pure CO2 (no cosolvent or surfactant needed) at temperatures close to 30°C and pressures below 210 bars. The solubilities of the different polymeric products are strongly depend on the polymer hydrogen content and molecular weight. DA - 1999/6/15/ PY - 1999/6/15/ DO - 10.1016/S0896-8446(99)00005-4 VL - 15 IS - 2 SP - 173-179 SN - 1872-8162 KW - fluorinated polymers KW - new solvent KW - solubility measurement KW - stone protection KW - supercritical carbon dioxide ER - TY - JOUR TI - Preparation and characterization of liposomal systems entrapping the boronated compound o-carboranylpropylamine AU - Moraes, A. M. AU - Santana, M. H. A. AU - Carbonell, R. G. T2 - Journal of Microencapsulation AB - Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when the stable isotope, Boron-10, is irradiated with low-energy thermal neutrons to yield ionizing Helium and Lithium ions that are highly damaging and usually lethal to cells. The successful treatment of cancer by BNCT requires the selective concentration of Boron-10 within malignant tumours. Liposomes have been used as therapeutic compound delivery vehicles for in vivo application, including several anticancer agents. The ability of the boron-containing compound, o-carboranylpropylamine chloride, to accumulate within unilamellar liposomes in response to a transmembrane pH gradient is evaluated. Characterization of the systems obtained is performed for conventional and polyethylene glycol (PEG)-modified (stealth) liposomes, in terms of lipid and CPA contents, vesicle size and stability in detergent solutions. Results demonstrate that CPA loading and vesicle stability can be controlled by the experimental procedure. The loading of CPA into liposomes with average diameters of 100 nm is estimated at 13000 molecules per vesicle for the most stable systems. CPA toxicity to normal human peripheral blood lymphocytes and to adherent glioblastoma multiforme SK-MG-1 cells in vitro is observed to decrease as a result of the entrapment of CPA in liposomes. DA - 1999/// PY - 1999/// DO - 10.1080/026520499288834 VL - 16 IS - 5 SP - 647-664 ER - TY - JOUR TI - Affinity chromatographic screening of soluble combinatorial peptide libraries AU - Huang, PY AU - Carbonell, RG T2 - BIOTECHNOLOGY AND BIOENGINEERING AB - Affinity chromatography using immobilized S-protein was used for the screening of affinity peptide ligands from two soluble peptide libraries. Peptide library I consisted of octamers with glycine (G) at both termini of each peptide, i.e. GXXXXXXG. The six center positions were constructed using random sequences of six L-amino acids (Y, N, F, E, V, and L). Peptide library II also consisted of octamers but with glycine and valine (V) at both termini of each peptide (GVZZZZVG). The four variable center positions of peptide library II were random sequences of 18 L-amino acids. Peptides that were retained specifically on the immobilized S-protein column were eluted by 2% acetic acid. The peptides in the acid eluate were further separated using reversed-phase HPLC. Each separated peptide fraction was collected and the peptide sequences deconvoluted by mass spectrometry (MS/MS). The screenings of peptide libraries I and II resulted in 12 and 7 affinity peptides, respectively. Eight out of the twelve peptides from peptide library I contained the clear consensus sequence NFEV. Peptide library II resulted in affinity peptides with the sequences GVNFEVVG, GVNFTVVG and GVFFEL(I)VG. The advantages and limitations of affinity chromatography in peptide library screening are discussed. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 633–641, 1999. DA - 1999/6/20/ PY - 1999/6/20/ DO - 10.1002/(SICI)1097-0290(19990620)63:6<633::AID-BIT1>3.0.CO;2-C VL - 63 IS - 6 SP - 633-641 SN - 0006-3592 KW - affinity chromatography KW - affinity ligand KW - combinatorial libraries KW - peptide KW - soluble peptide library ER - TY - JOUR TI - Coupling of hydrodynamics and chemical reaction in gas-lift reactors AU - Marquez, H. A. AU - Saez, A. E. AU - Carbonell, R. G. AU - Roberts, G. W. T2 - AIChE Journal AB - Abstract A model was developed to study the strong coupling between hydrodynamics and chemical reaction that occurs in external‐loop gas‐lift reactors. The model predicts the liquid circulation rate, as well as the axial profiles of gas holdup, pressure, gas and liquid velocity, and reactant conversion in the riser. The study on the first‐order, irreversible, isothermal reaction in the gas phase nA→B with a change in the number of moles on reaction shows that for n>1, the gas holdup decreases along the riser, the liquid circulation rate is lower than that in the absence of reaction, and liquid circulation decreases as n and k increase. The bubble radius at the sparger and the inlet gas composition can have important effects on reactor performance. Scale‐up strategies that involve increasing the reactor length result in higher reactant conversion, but a lower ratio of liquid circulation rate to gas feed rate. DA - 1999/// PY - 1999/// DO - 10.1002/aic.690450220 VL - 45 IS - 2 SP - 410-423 ER - TY - JOUR TI - Hydrodynamics of gas-lift reactors with a fast, liquid-phase reaction AU - Marquez, MA AU - Amend, RJ AU - Carbonell, RG AU - Saez, AE AU - Roberts, GW T2 - CHEMICAL ENGINEERING SCIENCE AB - The reactive absorption of CO2 into concentrated KOH solutions was studied in an external-loop, gas-lift reactor. Three different inlet gas compositions were used: air, 50–50 vol% air–CO2, and pure CO2. The downcomer liquid velocity and the axial profile of the cross-sectionally averaged gas holdup in the riser were measured. The reaction is so fast that the CO2 is consumed appreciably along the riser, and this causes a significant reduction in the liquid circulation relative to a system with no reaction. A one-dimensional, pseudo-steady-state model has been developed to describe the interactions of hydrodynamics, mass transfer, and chemical reaction for the bubbly flow regime in the riser. The model considers mass transfer from the gas to the liquid phase and its enhancement due to the chemical reaction, and is based on the spatially averaged equations of continuity, momentum, and macroscopic mechanical energy. The rate of liquid circulation, and the axial variation of gas holdup, gas composition, pressure, and gas and liquid velocity, are predicted. The gas/liquid mass transfer coefficient and the bubble radius at the sparger, neither of which was known a priori, were used to minimize the error of the data with respect to the model. DA - 1999/7// PY - 1999/7// DO - 10.1016/S0009-2509(98)00351-0 VL - 54 IS - 13-14 SP - 2263-2271 SN - 0009-2509 KW - carbon dioxide KW - gas-lift reactor KW - hydrodynamics KW - mass transfer KW - modeling KW - potassium hydroxide ER - TY - JOUR TI - Peptide affinity chromatography process for adsorption of fibrinogen AU - Lucena, SL AU - Carbonell, RG AU - Santana, CC T2 - POWDER TECHNOLOGY AB - Fibrinogen is a 340 kDa protein molecule also known as Factor I. Its synthesis occurs in the liver of animals. In human beings around 2.6 g/l fibrinogen is found in the circulatory plasma playing a very important role in the blood coagulation. Due to the biological functions and characteristics of fibrinogen, the development of new techniques for separating and purifying fibrinogen from human plasma is a current challenge. Affinity chromatography based on peptide libraries has become known as a powerful technique for dealing with protein molecules. The lack of many important parameters involved in such systems has limited the scale up. In this paper a way to obtain parameters such as the adsorption rate constants, by fitting the breakthrough curves, is presented. Dynamic experiments were carried out on HPLC (High Performance Liquid Chromatography) columns packed with resins, where the peptide FLLVPL was immobilized. This modified resin was also used for equilibrium experiments. This set of experiments allowed us to determine the maximum binding capacity, the dissociation constant and the lumped and intrinsic forward rate constants for resins with two different peptide densities (41.3 and 67.7 μmol of peptide/g resin). The mathematical model describing the breakthrough curve uses the Langmuir type isotherm, and the axial dispersion was ignored. DA - 1999/2// PY - 1999/2// DO - 10.1016/S0032-5910(98)00169-7 VL - 101 IS - 2 SP - 173-177 SN - 0032-5910 KW - affinity chromatography KW - peptide libraries KW - proteins KW - adsorption KW - fibrinogen ER -