Single and binary protein electroultrafiltration using poly(vinyl-alcohol)-carbon nanotube (PVA-CNT) composite membranes.

Electrically conductive composite ultrafiltration membranes composed of carbon nanotubes have exhibited efficient fouling inhibition in wastewater treatment applications. In the current study, poly(vinyl-alcohol)-carbon nanotube membranes were applied to fed batch crossflow electroultrafiltration of dilute (0.1 g/L of each species) single and binary protein solutions of α-lactalbumin and hen egg-white lysozyme at pH 7.4, 4 mM ionic strength, and 1 psi. Electroultrafiltration using the poly(vinyl-alcohol)-carbon nanotube composite membranes yielded temporary enhancements in sieving for single protein filtration and in selectivity for binary protein separation compared to ultrafiltration using the unmodified PS-35 membranes. Assessment of membrane fouling based on permeate flux, zeta potential measurements, and scanning electron microscopy visualization of the conditioned membranes indicated significant resulting protein adsorption and aggregation which limited the duration of improvement during electroultrafiltration with an applied cathodic potential of -4.6 V (vs. Ag/AgCl). These results imply that appropriate optimization of electroultrafiltration using carbon nanotube-deposited polymeric membranes may provide substantial short-term improvements in binary protein separations

COREGULATORY MECHANISMS OF CELLULAR RECRUITMENT IN FIBROCALCIFIC AORTIC VALVE DISEASE

206 pagesCOREGULATORY MECHANISMS OF CELLULAR RECRUITMENT IN FIBROCALCIFIC AORTIC VALVE DISEASE Terence William Gee, Ph. D. Cornell University 2020 The objective of this thesis was to develop and implement in vitro and in vivo model systems to understand complex, collaborative cellular mechanisms underpinning calcific aortic valve disease, an increasingly prevalent cardiovascular pathology lacking effective early diagnostic and therapeutic strategies save for invasive prosthetic replacement surgery. Through this work we have identified the role for canonical NF_B functioning as a “gatekeeper” for valve endothelial cell initiation and active participation in degenerative tissue calcification and identified this pathway as a promising therapeutic target for further preclinical evaluation. We further developed an in vitro platform through which cocultured endothelial and interstitial cells develop emergent, macro-calcific lesion features with underlying cellular and molecular signaling features recapitulative of the human etiology. Through these respective works we identify a subpopulation of endothelial derived mesenchymal progenitors, likely derived via post-natal reactivation of the Endothelial-to-Mesenchymal Transformation process, as being crucial role-players of the pathogenic process. Lastly, we build upon these systems to interrogate the diverse role of the Notch cell-fate decision making pathway in regulating valvular cell calcific transformation and matrix remodeling activity. The hope is that from the knowledge gleaned from this work, and by establishing these model systems, we can better understand the pathobiology of this and identify effective diagnostic markers for the disease or therapeutic candidates for its treatment.2022-08-2

Processing of an ultrafine-grained titanium by high-pressure torsion: an evaluation of the wear properties with and without a TiN coating

A commercial purity (CP) Grade 2 Ti was processed by high-pressure torsion (HPT) using an imposed pressure of 3.0 GPa at room temperature. The HPT processing reduced the grain size from ~8.6 ?m in the as-received state to ultra-fine grains (UFG) of ~130 nm after HPT. Tensile testing showed the HPT-processed Ti exhibited a good combination of high ultimate tensile strength (~940 MPa) and a reasonable elongation to failure (~23 %). Physical vapour deposition was used to deposit TiN coatings, with a thickness of 2.5 ?m, on Ti samples both with and without HPT processing. Scratch tests showed the TiN coating on UFG Ti had a critical failure load of ~22.5 N whereas the load was only ~12.7 N for the coarse-grained Ti. The difference is explained using a simple composite hardness model.Wear tests demonstrated an improved wear resistance of TiN coating when using UFG Ti as the substrate. The results suggest that CP Ti processed by HPT and subsequently coated with TiN provides a potentially important material for use in bio-implants

Single and binary protein electroultrafiltration using poly(vinyl-alcohol)-carbon nanotube (PVA-CNT) composite membranes.

Electrically conductive composite ultrafiltration membranes composed of carbon nanotubes have exhibited efficient fouling inhibition in wastewater treatment applications. In the current study, poly(vinyl-alcohol)-carbon nanotube membranes were applied to fed batch crossflow electroultrafiltration of dilute (0.1 g/L of each species) single and binary protein solutions of α-lactalbumin and hen egg-white lysozyme at pH 7.4, 4 mM ionic strength, and 1 psi. Electroultrafiltration using the poly(vinyl-alcohol)-carbon nanotube composite membranes yielded temporary enhancements in sieving for single protein filtration and in selectivity for binary protein separation compared to ultrafiltration using the unmodified PS-35 membranes. Assessment of membrane fouling based on permeate flux, zeta potential measurements, and scanning electron microscopy visualization of the conditioned membranes indicated significant resulting protein adsorption and aggregation which limited the duration of improvement during electroultrafiltration with an applied cathodic potential of -4.6 V (vs. Ag/AgCl). These results imply that appropriate optimization of electroultrafiltration using carbon nanotube-deposited polymeric membranes may provide substantial short-term improvements in binary protein separations

Effect of grain size on the micro-tribological behavior of pure titanium processed by high-pressure torsion

The micro-wear behavior of commercial pure Ti was investigated before and after processing by high pressure torsion (HPT) to provide comparisons over a range of grain sizes. The HPT-processed Ti had an average grain size of ?130 nm while the as-received and HPT plus annealed samples had grain sizes of ?8.6 m and ?607 nm, respectively. The results show all Ti samples have a similar dynamic coef?cient of friction but different wear mechanisms. Wear of the coarse grained (CG) Ti showed extensive plastic deformation and wedge formation which produced large wear debris whereas wear of the ultra-?ne grained (UFG) Ti was dominated by abrasive wear mechanisms and produced small wear debris. In addition, the UFG Ti showed a more homogenous wear grooving and a lower wear rate than CG Ti which suggests that UFG Ti is more suitable for wear applications.<br/

Single and binary protein electroultrafiltration using poly(vinyl-alcohol)-carbon nanotube (PVA-CNT) composite membranes.

Electrically conductive composite ultrafiltration membranes composed of carbon nanotubes have exhibited efficient fouling inhibition in wastewater treatment applications. In the current study, poly(vinyl-alcohol)-carbon nanotube membranes were applied to fed batch crossflow electroultrafiltration of dilute (0.1 g/L of each species) single and binary protein solutions of α-lactalbumin and hen egg-white lysozyme at pH 7.4, 4 mM ionic strength, and 1 psi. Electroultrafiltration using the poly(vinyl-alcohol)-carbon nanotube composite membranes yielded temporary enhancements in sieving for single protein filtration and in selectivity for binary protein separation compared to ultrafiltration using the unmodified PS-35 membranes. Assessment of membrane fouling based on permeate flux, zeta potential measurements, and scanning electron microscopy visualization of the conditioned membranes indicated significant resulting protein adsorption and aggregation which limited the duration of improvement during electroultrafiltration with an applied cathodic potential of -4.6 V (vs. Ag/AgCl). These results imply that appropriate optimization of electroultrafiltration using carbon nanotube-deposited polymeric membranes may provide substantial short-term improvements in binary protein separations

Tribology testing of ultrafine-grained Ti processed by high pressure torsion with subsequent coating

A grade 2 pure Ti was processed by high-pressure torsion (HPT) under 3.0 GPa for 10 revolutions to achieve an improved strength. Wear tests revealed that HPT only slightly improved the wear resistance of pure Ti. Subsequently, a TiN coating with a thickness of 2.5 ?m was deposited on different Ti substrates to improve the wear resistance. Both indentation and scratch testing demonstrated a much improved load-bearing capacity when ultrafine-grained Ti was chosen as the substrate compared with coarse-grained Ti. All results indicate that pure Ti processed by HPT, when combined with a subsequent coating, represents a good candidate material for bio-implant applications