scholarly journals Pervaporation Performance of Ag-PVA Nanocomposite Membranes: Effect of Operating Temperature

2019 ◽  
Vol 64 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Asmaa Selim ◽  
András József Tóth ◽  
Enikő Haáz ◽  
Dániel Fózer ◽  
Péter Mizsey
Keyword(s):  
Vinyl Alcohol ◽  
Water Flux ◽  
Sorption Process ◽  
Poly Vinyl Alcohol ◽  
Nanocomposite Membranes ◽  
Azeotropic Point ◽  
Influence Of Temperature On ◽  
And Diffusion

The features of pervaporation are continuously improved with the production of more and more efficient membranes. In our present study, silver nanoparticles are in-situ generated in a poly (vinyl alcohol) using solution-casting in order to enhance its capability for pervaporation. The membrane is tested on the case study of ethanol dehydration by pervaporation. Effect of silver content on the pervaporation separation index and the enrichment factor of the membrane at 15 % mass water at 40 °C are reported. Pervaporation data for nanocomposite membranes show around 100 % increase in the water permeance values while the intrinsic selectivity decreases that is typical for pervaporation membranes. The water permeances of original crosslinked PVA membrane and the 2.5 % silver loaded PVA membrane are 26.65 and 70.45 (g/m2.kPa.h), respectively. The values of total flux are closely related to water flux, showing that membranes could be successfully assigned to separate water from ethanol even at the azeotropic point. The influence of temperature on the efficiency of the pervaporation process, permeation parameter and diffusion coefficient of the feed component is also discussed. The negative heat of sorption (∆Hs) values calculated on the basis of the estimated Arrhenius activation energy values indicates that the sorption process is controlled by Langmuir's mode. Our results show that the 0.5 mass% silver loaded poly (vinyl alcohol) membrane exhibits excellent PV performance.

Ciprofloxacin-loaded alginate/poly (vinyl alcohol)/gelatin electrospun nanofiber mats as antibacterial wound dressings

2021 ◽  
pp. 152808372199746
Author(s):  
Tittaya Thairin ◽  
Patcharaporn Wutticharoenmongkol
Keyword(s):  
Weight Loss ◽  
Vinyl Alcohol ◽  
Diffusion Method ◽  
Poly Vinyl Alcohol ◽  
Burst Release ◽  
Electrospun Nanofiber ◽  
Total Immersion ◽  
Water Swelling ◽  
Nanofiber Mats ◽  
And Diffusion

Herein, ciprofloxacin (CIP)-loaded alginate/poly (vinyl alcohol)/gelatin (SPG) (CIP–SPG) nanofiber mats were successfully fabricated by electrospinning. The average fiber diameters of the mats before and after crosslinking were in the range of 190–260 and 385–484 nm, respectively. The chemical integrity of CIP remained intact after encapsulation into the mats. The degree of weight loss and water swelling decreased with an increase in the gelatin content of the electrospun nanofiber mats. A release study was carried out by total immersion and diffusion methods using phosphate buffer as a release medium. Burst release of CIP was observed in case of the total immersion method, while a more sustained release was observed in case of the diffusion method. The maximum amounts of CIP released during total immersion and diffusion were in the range of 70–90% and 72–85%, respectively. For both the total immersion and diffusion methods, the released amounts of CIP decreased and the release slowed down with an increase in the gelatin content; this result is consistent with the weight loss and water swelling values. The Young’s modulus increased, while the tensile strength and strain at break decreased with an increase in the gelatin content. The CIP–SPG nanofiber mats were slightly toxic to L929 mouse fibroblasts as evaluated by indirect cytotoxicity assay. The electrospun CIP–SPG nanofiber mats exhibited excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. These results reveal that the electrospun CIP–SPG nanofiber mats are potentially promising materials for wound healing applications.

scholarly journals Can post-mortem MRI be used as a proxy for in vivo? A case study

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Baayla D C Boon ◽  
Petra J W Pouwels ◽  
Laura E Jonkman ◽  
Matthijs J Keijzer ◽  
Paolo Preziosa ◽  
...  
Keyword(s):  
White Matter ◽  
Rating Scales ◽  
Brain Volume ◽  
Brain Mri ◽  
Post Mortem ◽  
Early Onset Alzheimer’S Disease ◽  
And Diffusion

Abstract Post-mortem in situ MRI has been used as an intermediate between brain histo(patho)logy and in vivo imaging. However, it is not known how comparable post-mortem in situ is to ante-mortem imaging. We report the unique situation of a patient with familial early-onset Alzheimer’s disease due to a PSEN1 mutation, who underwent ante-mortem brain MRI and post-mortem in situ imaging only 4 days apart. T1-weighted and diffusion MRI was performed at 3-Tesla at both time points. Visual atrophy rating scales, brain volume, cortical thickness and diffusion measures were derived from both scans and compared. Post-mortem visual atrophy scores decreased 0.5–1 point compared with ante-mortem, indicating an increase in brain volume. This was confirmed by quantitative analysis; showing a 27% decrease of ventricular and 7% increase of whole-brain volume. This increase was more pronounced in the cerebellum and supratentorial white matter than in grey matter. Furthermore, axial and radial diffusivity decreased up to 60% post-mortem whereas average fractional anisotropy of white matter increased approximately 10%. This unique case study shows that the process of dying affects several imaging markers. These changes need to be taken into account when interpreting post-mortem MRI to make inferences on the in vivo situation.

Carbon nanotubes for reinforcement of plastics? A case study with poly(vinyl alcohol)

2007 ◽  
Vol 67 (7-8) ◽  
pp. 1640-1649 ◽  
Author(s):  
K RYAN ◽  
M CADEK ◽  
V NICOLOSI ◽  
D BLOND ◽  
M RUETHER ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol

Changes in free volume and gas permeation properties of poly(vinyl alcohol) nanocomposite membranes modified using cage‐structured polyhedral oligomeric silsesquioxane

2020 ◽  
Vol 138 (10) ◽  
pp. 49953
Author(s):  
Valiya Parambath Swapna ◽  
Abitha Vayyaprontavida Kaliyathan ◽  
Vakkoottil Sivadasan Abhisha ◽  
Hanna Joseph Maria ◽  
Padinharu Madathil Gopalakrishnan Nambissan ◽  
...  
Keyword(s):  
Free Volume ◽  
Vinyl Alcohol ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
Gas Permeation ◽  
Poly Vinyl Alcohol ◽  
Nanocomposite Membranes ◽  
Oligomeric Silsesquioxane ◽  
Permeation Properties

In situ nanofibrillar reinforced biodegradable composites based on thermoplastic poly (vinyl alcohol)/poly (lactic acid)

2018 ◽  
Vol 14 (3) ◽  
pp. 291 ◽  
Author(s):  
Zheng Guo ◽  
Yuerong Ba ◽  
Dong Liu ◽  
Wei Pan
Keyword(s):  
Lactic Acid ◽  
Vinyl Alcohol ◽  
Poly Lactic Acid ◽  
Poly Vinyl Alcohol ◽  
Biodegradable Composites

scholarly journals In Situ Preparation and Properties of Poly(vinyl alcohol)/Carboxymethyl Chitosan/Cyanidin Hydrogel Films

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Xiaojuan Zhang ◽  
Wenbin Cai ◽  
Lingyun Hao ◽  
Wei Zhang
Keyword(s):  
Vinyl Alcohol ◽  
Encapsulation Efficiency ◽  
Umbilical Vein ◽  
Antibacterial Activities ◽  
Carboxymethyl Chitosan ◽  
Poly Vinyl Alcohol ◽  
In Situ Preparation ◽  
Umbilical Vein Endothelial Cells ◽  
Hydrogel Films

This study synthesized poly(vinyl alcohol)/carboxymethyl chitosan/cyanidin (PVA/CMCS/CY) hydrogel films. First, PVA and CMCS were used to synthesize hydrogel films by ultraviolet irradiation. Meanwhile, CY was in situ combined into the hydrogel films through the electrostatic attraction between CMCS and CY. Next, the products were analyzed using Fourier-transform infrared spectroscopy, scanning electron microscopy, contact angle test, swelling analysis, and mechanical property test. The results revealed that compared with PVA/CMCS hydrogel films, the PVA/CMCS/CY hydrogel films had an interporous structure and good swelling and mechanical properties. Moreover, the drug release experiments demonstrated that the PVA/CMCS/CY hydrogel films had a CY encapsulation efficiency of 33.5% with a sustained CY release of up to 60 h. Furthermore, the examined antibacterial activities against Staphylococcus aureus and Escherichia coli showed that the porous PVA/CMCS/CY hydrogel films exhibited a certain inhibition. Cell viability experiments demonstrated that the PVA/CMCS/CY films displayed no obvious cytotoxicity to human umbilical vein endothelial cells.

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