scholarly journals A novel esterase DacApva from Comamonas sp. strain NyZ500 with deacetylation activity for acetylated polymer polyvinyl alcohol

2021 ◽  
Author(s):  
Chao-Fan Yin ◽  
Ying Xu ◽  
Shi-Kai Deng ◽  
Wen-Long Yue ◽  
Ning-Yi Zhou
Keyword(s):  
Polyvinyl Alcohol ◽  
High Energy ◽  
Water Soluble ◽  
Backbone Cleavage ◽  
Water Soluble Polymer ◽  
Prevotella Ruminicola ◽  
Rich Media ◽  
Acetyl Group ◽  
High Pollution ◽  
Novel Esterase

As a water-soluble polymer, the widely used polyvinyl alcohol (PVA) is produced from hydrolysis of polyvinyl acetate. Microbial PVA carbon backbone cleavage via a two-step reaction of dehydrogenation and hydrolysis has been well studied. Content of acetyl group is a pivotal factor affecting performance of PVA derivatives in industrial application, and deacetylation is a non-negligible part in PVA degradation. However, the genetic and biochemical studies of its deacetylation remain largely elusive. Here, Comamonas sp. strain NyZ500 was isolated for its capability of growing on acetylated PVA from activated sludge. A spontaneous PVA-utilization deficient mutant strain NyZ501 was obtained when strain NyZ500 was cultured in rich media. Comparative analysis between the genomes of these two strains revealed a fragment (containing a putative hydrolase gene dacApva) deletion in NyZ501 and dacApva-complemented strain NyZ501 restored the ability to grow on PVA. DacApva, which shares 21% identity with xylan esterase AxeA1 from Prevotella ruminicola 23, is a unique deacetylase catalyzing the conversion of acetylated PVA and its derivatives to deacetylated counterparts. This indicates that strain NyZ500 utilizes acetylated PVA via acetate as a carbon source to grow. DacApva also possessed the deacetylation ability for acetylated xylan and the antibiotic intermediate 7-aminocephalosporanic acid (7ACA) but the enzymes for the above two compounds had no activities against PVA derivatives. This study enhanced our understanding of the diversity of microbial degradation of PVA and DacApva characterized here is also a potential biocatalyst for the eco-friendly biotransformation of PVA derivatives and other acetylated compounds. IMPORTANCE: Water-soluble PVA, which possesses a very robust ability to accumulate in the environment, has a very grave environmental impact due to its widespread use in industrial and household applications. On the other hand, chemical transformation of PVA derivatives is currently being carried out at high energy consumption and high pollution conditions using hazardous chemicals (such as NaOH, methanol) under high temperatures. The DacApva reported here performs PVA deacetylation under mild conditions, then it has a great potential to be developed into an eco-friendly biocatalyst for biotransformation of PVA derivatives. DacApva also has deacetylation activity for compounds other than PVA derivatives, which facilitates its development into a broad-spectrum deacetylation biocatalyst for production of certain desired compounds.

scholarly journals Study on the Preparation and Lipophilic Properties of Polyvinyl Alcohol (PVA) Nanofiber Membranes via Green Electrospinning

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2514
Author(s):  
Jun Cong Ge ◽  
Guirong Wu ◽  
Sam Ki Yoon ◽  
Min Soo Kim ◽  
Nag Jung Choi
Keyword(s):  
Polyvinyl Alcohol ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Environmentally Friendly ◽  
Contact Angles ◽  
Water Soluble ◽  
Engine Oil ◽  
Bet Surface Area ◽  
Water Soluble Polymer ◽  
Nanofiber Membranes

As an environmentally friendly water-soluble polymer, polyvinyl alcohol (PVA) has attracted extensive attention because of its non-toxic, degradable, low cost, and good biocompatibility. Electrospinning is a kind of nanotechnology, and the nanofiber membrane prepared by it has the advantages of large surface area-to-volume ratios, nano- to micron-sized fibers, etc. Herein, a simple and facile one-step green electrospinning method was developed to fabricate various environmentally friendly PVA nanofiber membranes. The lipophilic properties of PVA membranes were investigated and optimized according different PVA concentrations. The PVA electrospun fiber prepared from the solution at a concentration of 10 wt% had the highest adsorption capacity for the adsorption of new and waste engine oils, and the waste engine oil adsorption capacity (12.70 g/g) was higher than that of new engine oil (11.67 g/g). It also has a relatively large BET surface area (12.05 m2/g), a pore volume (0.04 cm3/g), and an appropriate pore diameter (13.69 nm) and fiber diameter (174.21 nm). All electrospun PVA membranes showed excellent lipophilic properties due to their oil contact angles of much less than 30°. Therefore, PVA electrospun fibrous membranes have great application potential in the field of purifying engine oil due to the excellent lipophilic properties and oil absorption capacity.

scholarly journals Preparation and Pharmaco-Mechanical Characterization of Ketoprofen- Polyvinyl Alcohol Cryogel for Medical Applications

2019 ◽  
Vol 70 (3) ◽  
pp. 848-852
Author(s):  
Monica Iliuta Stamate ◽  
Lacramioara Ochiuz ◽  
Daniel Timofte ◽  
Bogdan Ciuntu ◽  
Cristina Ghiciuc ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Mechanical Characterization ◽  
Water Soluble ◽  
Mechanical Resistance ◽  
Medical Applications ◽  
Water Soluble Polymer ◽  
Different Temperatures ◽  
Polymeric Solutions ◽  
Equilibrium Swelling Ratio

Polyvinyl alcohol is a biocompatible polymer used very commonly both in pharmaceutical and medical fields. Being a water-soluble polymer, it is suitable for the manufacture of hydrogels as well as cryogels used for various medical applications. The present work describes the preparation, structural and physico-mechanical characterization of polyvinyl alcohol cryogels loaded with ketoprofen. By cryogenic technique the polymeric solutions are transformed under certain conditions into porous, elastic and very compressible structures. They are able to absorb a large amount of liquids that they give off by gentle compression. The prepared cryogels were evaluated for different physical, chemical and structural properties, as following: internal morphology, equilibrium swelling ratio and mechanical testing. The cryogel structures show good elasticity and optimal swelling at different temperatures. Due to these properties the studied cryogels are suitable for use in various medical applications involving liquid absorption, mechanical resistance and anti-inflammatory effect.

scholarly journals Effect of Polyvinyl Alcohol on the Rheological Properties of Cement Mortar

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 754
Author(s):  
Fang Liu ◽  
Baomin Wang ◽  
Yunqing Xing ◽  
Kunkun Zhang ◽  
Wei Jiang
Keyword(s):  
Polyvinyl Alcohol ◽  
Rheological Properties ◽  
Yield Stress ◽  
Cement Mortar ◽  
Chemical Properties ◽  
Degree Of Polymerization ◽  
Plastic Viscosity ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Hydrolysis Degree

Polyvinyl alcohol (PVA) is a kind of water-soluble polymer, which has been widely used in different industries due to its excellent mechanical and chemical properties. In this paper, the effects of polyvinyl alcohol with different hydrolysis and polymerization degrees on the rheological properties of cement mortar are studied. The results show that the rheological properties of PVA-modified cement mortar can be described by the modified Bingham model. The yield stress of modified cement mortar is less than that of unmodified mortar when the degree of polymerization and the content of PVA are small. With the increase of polyvinyl alcohol content and polymerization degree, the yield stress and plastic viscosity of modified cement mortar increase sharply, which are larger than those of the unmodified cement mortar. However, the effect of hydrolysis degree of PVA on yield stress and plastic viscosity of modified cement mortar is not obvious.

scholarly journals Electrospun synthesis of silver/poly (vinyl alcohol) nano-fibers: investigation antibacterial activity and flame retardant property

2021 ◽  
Author(s):  
Sara Azarakhsh ◽  
Hamed Bahiraei ◽  
Gholamhosain Haidari ◽  
Davood Ghanbar
Keyword(s):  
Polyvinyl Alcohol ◽  
Flame Retardant ◽  
Ag Nanoparticles ◽  
Average Particle Size ◽  
Water Soluble ◽  
Poly Vinyl Alcohol ◽  
Average Particle ◽  
Sem Images ◽  
Water Soluble Polymer ◽  
Nano Fiber

Abstract Polyvinyl alcohol (PVA) and Ag nanoparticles-embedded polyvinyl alcohol (Ag/PVA) nano-fibers have been synthesized successfully via the electro-spinning technique at room temperature. XRD patterns confirmed the presence of Ag nanoparticles in the electro-spinning PVA nano-fibers. FE-SEM images displayed that silver nanoparticles with an average particle size of 32 nm are uniformly dispersed in PVA nano-fibers. Also, the average diameter of Ag/PVA nano-fibers was estimated to be 142 nm. The EDX analysis of Ag/PVA nano-fiber determined the aggregation of Ag nanoparticles in the range of polymer nano-fibers. The antibacterial property of Ag/PVA nano-fiber for inhibition of Escherichia coli (E-coli) growth was approved. Since polyvinyl alcohol is a biocompatible and water-soluble polymer, it can be considered as unique candidate for the preparation of wound dressing nano-fibers. It is also found that the nontoxic nanostructures can appropriately enhance both flame retardant and thermal stability properties of the Ag/PVA matrix. These results show that the Ag/PVA nano-fibers may find practical applications as self-reinforced medical devices and tissue-engineering scaffolds.

Preparation and properties of melamine formaldehyde resin modified by functionalized nano-SiO2 and polyvinyl alcohol

2020 ◽  
pp. 096739112090354
Author(s):  
Zhu Xiong ◽  
Ning Chen ◽  
Qi Wang
Keyword(s):  
Thermal Stability ◽  
Impact Strength ◽  
Polyvinyl Alcohol ◽  
Flame Retardant ◽  
Flame Retardancy ◽  
Water Soluble ◽  
Hot Water ◽  
Formaldehyde Resin ◽  
Melamine Formaldehyde ◽  
Water Soluble Polymer

Melamine formaldehyde (MF) resin is a thermosetting polymer with superior flame retardancy and high thermal stability and is widely used in fire-retardant coatings, flame-retardant sheets, heat-resistant filter materials, and so on. However, its further application is restricted by its extreme brittleness and poor impact strength. In this article, polyvinyl alcohol (PVA), a water-soluble polymer with high toughness and elasticity, which can be well blended with MF prepolymer in hot water, was used to improve the toughness of MF resin. The nano-silicon dioxide (SiO2) particles modified by KH-550 were used to improve the compatibility between MF prepolymer and PVA. Moreover, the modified nano-SiO2 can simultaneously enhance the toughness and impact the strength of MF resin. The interaction of components, fractography, thermal stability, flame retardancy, and mechanical properties of the modified MF resin was studied systematically. Fourier transform infrared results indicate that KH-550 was successfully grafted onto the surface of nano-SiO2. The grafted nano-SiO2 shows better dispersion in the matrix than the unmodified one, furthermore improving the compatibility and interface adhesion between MF and PVA. When PVA content is 20%, the obtained material has good thermal stability ( T max > 350°C), flame-retardant properties (UL-94 V-0 rating and limited oxygen index = 42%), and toughness (elongation at break > 20% and unnotched impact strength > 13 kJ m−2).

Polyvinyl alcohol as foaming agent in foam formed paper

TAPPI Journal ◽  
2019 ◽  
Vol 18 (8) ◽  
pp. 475-485
Author(s):  
JENS-MIKAEL GOTTBERG ◽  
TIMO LAPPALAINEN ◽  
KRISTIAN SALMINEN
Keyword(s):  
Polyvinyl Alcohol ◽  
Molar Mass ◽  
Sodium Dodecyl ◽  
Strength Properties ◽  
Water Soluble ◽  
Degree Of Hydrolysis ◽  
Hydroxyl Groups ◽  
Water Soluble Polymer ◽  
Foaming Agent ◽  
Air Content

The use of polyvinyl alcohol (PVOH or PVA) as a foaming agent in foam formed paper was investigated. Polyvinyl alcohol is a linear, nonionic water-soluble polymer. It has hydrophobic and hydrophilic parts that give it a surface-active character. PVOH is mainly characterized by degree of hydrolysis and molar mass. Degree of hydrolysis is given as mol-% hydroxyl groups on the polymer. Molar mass is measured indirectly by measuring the viscosity of a 4% PVOH solution. The results show that the degree of hydrolysis of PVOH had a strong effect on the foamability of PVOH. Foamability decreased strongly when the degree of hydrolysis increased from 88 to 98 mol-%. The effect of molar mass on foamability was weaker. We saw an increase in foam stability and bubble size with increasing molar mass, but we did not see any effect on maximum air content. PVOH dosage needed to reach >70% air content (Φ) varied from 2 g/l up to 10.5 g/l, and the lowest addition levels of PVOH needed were achieved with a low molar mass PVOH with a low degree of hydrolysis. The best strength properties were achieved when using fully hydrolyzed PVOH as the foaming agent. Strength properties (both in- and out-of-plane) of samples made using PVOH were better than those made using an anionic foaming agent (sodium dodecyl sulfate, SDS). By adding PVOH binder fibers to the pulp, we were able to further enhance the strength properties of paper and board.

Mixing of oxidized starch and polyvinyl alcohol for surface sizing of paper

2019 ◽  
Vol 34 (3) ◽  
pp. 343-353 ◽  
Author(s):  
Shubhang Bhardwaj ◽  
Nishi Kant Bhardwaj
Keyword(s):  
Polyvinyl Alcohol ◽  
Water Soluble ◽  
Air Leak ◽  
Water Soluble Polymer ◽  
Oxidized Starch ◽  
Base Paper ◽  
Surface Sizing ◽  
Film Forming ◽  
Breaking Length ◽  
Economic Constraints

Abstract Surface sizing chemical (mostly oxidized or enzymatically modified starch) flows into the pores of cellulose network and also remains on the surface affecting the surface and intrinsic properties of paper. Polyvinyl alcohol (PVA) can be used for surface sizing because it is a water soluble polymer and has high film forming ability. Due to economic constraints, using PVA alone for surface sizing is not a good option. Current study explored the effects of using oxidized starch and PVA in mixed ratios (80:20, 50:50 and 20:80) on mechanical and surface properties of paper. The surface sizing with sizing weight of 3.5±0.3 g/m2 was done. The results of the study showed that the breaking length, burst index, air permeance, gloss, Cobb60 and optical properties like brightness, whiteness, flouroscence of paper were better for mixed ratios in comparison to only oxidized starch. After surface sizing with PVA, the value of air permeance (time of air leak) was increased to 200 Gurley second in comparison to 9 only for base paper. Surface sizing with blends of oxidized starch solution and PVA solution i. e. 80S+20P, 50S+50P and 20S+80P increased the time of air leak by 900 %, 1455 % and 1788 %, respectively in comparison to base paper.

scholarly journals EFFECT OF WATER-SOLUBLE POLYMER NV-1A ON ELECTROCHEMICAL PARAMETERS OF SULFUR ELECTRODE

2021 ◽  
Vol 87 (11) ◽  
pp. 55-59
Author(s):  
Oleksandr Krushevskyi ◽  
MiaoMiao Zhou ◽  
Oleksandr Potapenko ◽  
Anna Potapenko
Keyword(s):  
Impedance Spectroscopy ◽  
Coulombic Efficiency ◽  
Active Material ◽  
Specific Capacity ◽  
High Energy ◽  
Water Soluble ◽  
Main Process ◽  
High Current ◽  
Water Soluble Polymer ◽  
Sulfur Electrode

Studies have shown the possibility of a long cycle of sulfur electrode with a high content of active material. The use of water-soluble binder material NV-1A leads to the realization of high current loads in the Li-S battery. Impedance spectroscopy has shown that the low coulombic efficiency in the cycling of the sulfur electrode is primarily due to the spontaneous dissolution of sulfur in the electrolyte, which requires high energy consumption when charging the Li-S battery. The reduction of the specific capacity during cycling is associated with the formation and accumulation of non-conductive films of short-chain polysulfides. On the basis of the conducted researches and the review of the literature sources ways of overcoming of this problem are offered. The ability of cycling the sulfur electrodes at the high current loads has been shown. The discharge capacity values of the sulfur electrodes at the current load 790 mA∙cm-2 are 500 і 420 mAh∙g-1 on the 5-th and 100-th cycles, accordingly. Using the method of impedance spectroscopy, it has been supposed that the formation and accumulation of unconductive Li2S2 / Li2S phases is the main process, which induce the quick capacity reduction of Li - S batteries upon cycling.

Neurotoxicity and Neuroprotective Effects of Polyimides (PI) and Polyphenylenevinylene (PPV) against Hydrogen Peroxide (H2O2)

2011 ◽  
Vol 8 (2) ◽  
pp. 33
Author(s):  
Norfaezah Mazalan ◽  
Mazatulikhma Mat Zain ◽  
Nor Saliyana Jumali ◽  
Norhanim Mohalid ◽  
Zurina Shaameri ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Drug Delivery Systems ◽  
Neuronal Cells ◽  
Water Soluble ◽  
Brain Delivery ◽  
Specific Therapy ◽  
Neuroprotective Effects ◽  
Water Soluble Polymer ◽  
Site Specific ◽  
Novel Drugs

Recently, research and development in the field of drug delivery systems (DDS) facilitating site-specific therapy has reached significant progression. DDS based on polymer micelles, coated micro- and nanoparticles, and various prodrug systems including water-soluble polymer have been prepared and extensively studied as novel drugs designed for cancer chemotherapy and brain delivery. Since polymers are going to be used in human, this study has the interest of testing two types of polymer, polyimides (PI) and polyphenylenevinylene (PPV) on neuronal cells. The objective of this study was to determine the possible neurotoxicity and potential neuroprotective effects of PI and PPV towards SH-SY5Y neuronal cells challenged by hydrogen peroxide (H2O2) as an oxidant. Cells were pretreated with either PI or PPV for 1 hour followed by incubation for 24 hour with 100 µM of H2O2. MTS assay was used to assess cell viability. Results show that PI and PPV are not harmful within the concentration up to 10 µM and 100 µM, respectively. However, PI and PPV do not protect neuronal cells against toxicity induced by H2O2 or further up the cell death.

scholarly journals Self-Healing Polymer-Clay Hybrids by Facile Complexation of a Waterborne Polymer with a Clay

2021 ◽  
Author(s):  
Aranee Pleng Teepakakorn ◽  
Makoto Ogawa
Keyword(s):  
Vinyl Alcohol ◽  
Aqueous Media ◽  
Water Soluble ◽  
Poly Vinyl Alcohol ◽  
Self Healing ◽  
Soluble Polymer ◽  
Water Soluble Polymer ◽  
Smectite Clay

Water-induced self-healing materials were prepared by the hybridization of a water-soluble polymer, poly(vinyl alcohol), with a smectite clay by mixing in an aqueous media and subsequent casting. Without using chemical...

Sign in / Sign up

Export Citation Format

Share Document