3,708 research outputs found
Modeling Sorption Kinetics of Carbon Dioxide in Initially Glassy Polymers Using Non-Equilibrium Thermodynamics
No full textA direct comparison between membrane adsorber and packed column chromatography performance
No full textThe purpose of this work was to compare side by side the performance of packed bed and membrane chromatography adsorption processes for protein purification. The comparison was performed using anion exchange media with the same ligand immobilized on the adsorbing surface, namely the strong Q quaternary ammonium group, R-CH2-N+-(CH3)3, and bovine serum albumin (BSA) as a model protein. In addition, the stationary phase volume was held constant for each geometry (3 mL) and runs were executed using the same mobile phase superficial velocity. As expected, the packed bed column showed higher equilibrium binding of BSA at 66.9 mg/mL versus 43.04 mg/mL for the membrane adsorber. Dynamic binding capacities were also higher in the packed bed; for example, at 97.5 cm/h, a capacity of 62.8 mg/mL was measured for the packed bed versus 20.7 mg/mL for the membrane adsorber. The higher equilibrium and dynamic capacities of the packed bed are likely due to the higher surface area per unit volume of the resin. However, the maximum productivity for the membrane adsorber was 111 mg/(mL h), a value that was 3.3 times higher than the one of the packed column. The bed utilization - defined as the ratio of the dynamic binding capacity at 10% breakthrough to the saturation binding capacity - was also higher for the packed column at long residence times and lower at short residence times confirming the better performance of membrane chromatography at high flow rates
Nonwoven Ion-Exchange Membranes with High Protein Binding Capacity for Bioseparations
No full textThis study presents the preparation and characterization of UV-grafted polybutylene terepthalate (PBT) ion exchange nonwoven membranes for chromatographic purification of biomolecules. The PBT nonwoven was functionalized with sulfonate and secondary amine for cation and anion exchange (CEX and AEX), respectively. The anion exchange membrane showed an equilibrium static binding capacity of 1300 mg BSA/g of membrane, while the cationic membranes achieved a maximum equilibrium binding capacity of over 700 mg hIgG/g of membrane. The CEX and AEX membranes resulted in dynamic binding capacities under flow conditions, with a residence time of 0.1 min, of 200 mg hIgG/mL of membrane and 55 mg BSA/mL of membrane, respectively. The selectivity of the PBT-CEX membranes was demonstrated by purifying antibodies and antibody fragments (hIgG and scFv) from CHO cell culture supernatants in a bind-an-elute mode. The purity of the eluted samples exceeded 97%, with good log removal values (LRV) for both host cell proteins (HCPs) and DNA. The PBT-AEX nonwoven membranes exhibited a DNA LRV of 2.6 from hIgG solutions in a flow-through mode with little loss of product. These results indicate that these membranes have significant potential for use in downstream purification of biologics
On the Use of Carbon Dioxide in Microelectronics Processing
No full textThe low viscosity, low surface energy and highly controllable density and solubility properties of carbon dioxide near its critical point provide some excellent opportunities for its use in several processes in the fabrication of integrated circuits. This paper discusses the potential use of CO2 in photolithography. In particular, we are interested in the use of CO2 with surfactants and cosolvents for the removal of water from semiconductor wafers that have been developed in aqueous solvents. This approach would help eliminate the problem of image collapse. Other applications presented include the use of CO2 instead of high temperature heating to remove residual solvents prior to exposure, spin coating of photoresists and direct development using CO2. The use of CO2 in these applications raises some fundamental issues on the thermodynamics of interactions of high-pressure fluids with polymeric thin films that can affect both polymer dilatation and mass absorption
Development and characterization of green composites from bio-based polyethylene and peanut shell
No full textThis is the accepted version of the following article: Garcia-Garcia, D., Carbonell-Verdu, A., Jordá-Vilaplana, A., Balart, R. and Garcia-Sanoguera, D. (2016), Development and characterization of green composites from bio-based polyethylene and peanut shell. J. Appl. Polym. Sci. 43940 doi: 10.1002/app.43940, which has been published in final form at http://dx.doi.org/10.1002/app.43940[EN] In the present work, different compatibilizers, namely polyethylene-graft-maleic anhydride (PE-g-MA), polypropylene-graftmaleic anhydride (PP-g-MA), and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride (SEBS-g-MA) were used on green composites derived from biobased polyethylene and peanut shell (PNS) flour to improve particle polymer interaction. Composites of high-density polyethylene/peanut shell powder (HDPE/PNS) with 10 wt % PNS flour were compatibilized with 3 wt % of the abovementioned compatibilizers. As per the results, PP-g-MA copolymer lead to best optimized properties as evidenced by mechanical characterization. In addition, best particle matrix interface interactions with PP-g-MA were observed by scanning electron microscopy (SEM). Subsequently HDPE/PNS composites with varying PNS flour content in the 5 30 wt % range with PP-g-MA compatibilizer were obtained by melt extrusion and compounding followed by injection molding and were characterized by mechanical, thermal, and morphological techniques. The results showed that PNS powder, leads to an increase in mechanical resistant properties (mainly, flexural modulus, and strength) while a decrease in mechanical ductile properties, that is, elongation at break and impact absorbed energy is observed with increasing PNS flour content. Furthermore, PNS flour provides an increase in thermal stability due to the natural antioxidant properties of PNS. In particular, composites containing 30 wt % PNS powder present a flexural strength 24% and a flexural modulus 72% higher than the unfilled polyethylene and the thermo-oxidative onset degradation temperature is increased from 232 8C up to 2548C thus indicating a marked thermal stabilization effect. Resultant composites can show a great deal of potential as base materials for wood plastic composites.This research was supported by the Ministry of Economy and Competitiveness -MINECO, Ref: MAT2014-59242-C2-1-R. Authors also thank to "Conselleria d'Educacio, Cultura i Esport" - Generalitat Valenciana, Ref: GV/2014/008 for financial support. A. Carbonell-Verdu wants to thank Universitat Politecnica de Valencia for financial support through an FPI grant. D. Garcia-Garcia wants to thanks the Spanish Ministry of Education, Culture and Sports for the financial support through an FPU grant (FPU13/06011).García García, D.; Carbonell Verdú, A.; Jorda-Vilaplana, A.; Balart Gimeno, RA.; García Sanoguera, D. (2016). Development and characterization of green composites from bio-based polyethylene and peanut shell. Journal of Applied Polymer Science. 133(37):1-12. https://doi.org/10.1002/APP.43940S1121333
Equine fasciolosis due to <i>Fasciola hepatica</i> in the Community of Madrid (Spain): First report of a rare parasitic infection in horses
No full textJustificación de autores:
Carolina R. Sanz and Arancha Meana conceived and designed the project. Carolina R. Sanz performed the clinical exams and acquired the biological samples. Carolina R. Sanz and Juan David Carbonell collected the snails and performed the morphological identification. Carolina R. Sanz analysed the clinical samples and interpreted the data. Guadalupe Miró and Arancha Meana supervised the laboratory analyses. Carolina R. Sanz wrote the original draft. All authors reviewed and approved the final version of the manuscript.
Beca de Predoctoral Carolina Rodríguez: CT42/18-CT43/18We reported for the first time a confirmed case of equine fasciolosis in the Community of Madrid (Spain). Here, we described the clinical presentation, diagnostic approach and treatment of the affected horse, as well as the seroprevalence of Fasciola hepatica in the equestrian centre where it was detected. A 12-year-old mare presented in autumn with a 3-month history of decreased performance, lethargy and progressive weight loss, despite a normal appetite. Haematology and biochemical profile revealed normocytic and normochromic anaemia, leukopenia, and the sorbitol dehydrogenase value was at the upper reference limit. F. hepatica eggs were found in coprology, along with a high load of gastrointestinal nematodes. Flukicide treatment based on the administration of two doses of closantel (10 mg/kg, orally), given 10 weeks apart, was effective against F. hepatica infection in this horse, with a noticeable clinical improvement observed 1 month post-treatment. No recurrence was observed in the 12-month follow-upUniversidad Complutense de MadridBanco SantanderDepto. de Sanidad AnimalFac. de VeterinariaTRUEpu
Interfacial Effects and the Anomalous Swelling Behavior of Supported Polymer Thin Films in Supercritical Carbon Dioxide
No full textIminodiacetic acid (IDA) cation-exchange nonwoven membranes for efficient capture of antibodies and antibody fragments
No full textThere is strong need to reduce the manufacturing costs and increase the downstream purification efficiency of high-value therapeutic monoclonal antibodies (mAbs). This paper explores the performance of a weak cation-exchange membrane based on the coupling of IDA to poly(butylene terephthalate) (PBT) nonwoven fabrics. Uniform and conformal layers of poly(glycidyl methacrylate) (GMA) were first grafted to the surface of the nonwovens. Then IDA was coupled to the polyGMA layers under optimized conditions, resulting in membranes with very high permeability and binding capacity. This resulted in IgG dynamic binding capacities at very short residence times (0.1–2.0 min) that are much higher than those achieved by the best cation-exchange resins. Similar results were obtained in the purification of a single-chain (scFv) antibody fragment. As is customary with membrane systems, the dynamic binding capacities did not change significantly over a wide range of residence times. Finally, the excellent separation efficiency and potential reusability of the membrane were confirmed by five consecutive cycles of mAb capture from its cell culture harvest. The present work provides significant evidence that this weak cation-exchange nonwoven fabric platform might be a suitable alternative to packed resin chromatography for low-cost, higher productivity manufacturing of therapeutic mAbs and antibody fragments
First results of a reprocessing workflow on a 2D vintage reflection seismic profile across the area struck by the 2016 Mw 6.5 Norcia earthquake (Central Italy).
No full textCHARACTERIZATION OF MICROCELLULAR BIODEGRADABLE POLYMERIC FOAMS PRODUCED FROM SUPERCRITICAL CARBON DIOXIDE SOLUTIONS
No full textThe formation of foams of biodegradable poly(e-caprolactone) (PCL) from CO2 solns. in molten PCL was investigated. This study included characterization of the CO2 diffusion and equil. soly. in molten PCL in contact with supercrit. CO2 (scCO2). Expts. were performed at 70, 80, and 90 °C at CO2 pressures up to 25 MPa. The effective mutual diffusivity of CO2 in molten PCL was measured as a function of the CO2 pressure. The data revealed a dramatic increase in apparent effective diffusivity at elevated pressure, likely related to the formation of fluid bubbles, phase-sepd. from the previously homogeneous, molten PCL soln. of CO2. Microcellular PCL foams were produced by starting from an equil. CO2-PCL soln. at 70 °C over a wide range of initial pressures (from 6.9 to 32 MPa) by quenching down to foaming temps. (from 24 to 30 °C) followed by rapid depressurization to atm. pressure. Foam structures were characterized by SEM, and cell sizes and d. were detd. quant. The various foam structures were analyzed and interpreted in connection with the independently measured kinetics and equil. of CO2 sorption in PCL by considering the effects of starting pressure and foaming temp. on bubble nucleation and growth
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