scholarly journals Enzymes Involved in Plastic Degradation

2021 ◽  
pp. 95-110
Author(s):  
S.Z.Z. Cobongela
Keyword(s):  
Polyethylene Terephthalate ◽  
Synthetic Polymers ◽  
Chemical Degradation ◽  
Natural Resistance ◽  
Aquatic Life ◽  
Carbon Backbone ◽  
Catabolic Enzymes ◽  
Plastic Degradation ◽  
Global Increase ◽  
Physical And Chemical

The global increase in production of plastic and accumulation in the environment is becoming a major concern especially to the aquatic life. This is due to the natural resistance of plastic to both physical and chemical degradation. Lack of biodegradability of plastic polymers is linked to, amongst other factors, the mobility of the polymers in the crystalline part of the polyesters as they are responsible for enzyme interaction. There are significantly few catabolic enzymes that are active in breaking down polyesters which are the constituents of plastic. The synthetic polymers widely used in petroleum-based plastics include polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane (PUR), polystyrene (PS), polyamide (PA) and polyethylene terephthalate (PET) being the ones used mostly. Polymers with heteroatomic backbone such as PET and PUR are easier to degrade than the straight carbon-carbon backbone polymers such as PE, PP, PS and PVC.

scholarly journals Vascular Tissue Engineering: Recent Advances in Small Diameter Blood Vessel Regeneration

2014 ◽  
Vol 2014 ◽  
pp. 1-27 ◽  
Author(s):  
Valentina Catto ◽  
Silvia Farè ◽  
Giuliano Freddi ◽  
Maria Cristina Tanzi
Keyword(s):  
Tissue Engineering ◽  
Cardiovascular Diseases ◽  
Blood Vessel ◽  
Polyethylene Terephthalate ◽  
Vascular Tissue ◽  
Vascular Grafts ◽  
Small Diameter ◽  
Synthetic Polymers ◽  
Vascular Tissue Engineering ◽  
Vessel Regeneration

Cardiovascular diseases are the leading cause of mortality around the globe. The development of a functional and appropriate substitute for small diameter blood vessel replacement is still a challenge to overcome the main drawbacks of autografts and the inadequate performances of synthetic prostheses made of polyethylene terephthalate (PET, Dacron) and expanded polytetrafluoroethylene (ePTFE, Goretex). Therefore, vascular tissue engineering has become a promising approach for small diameter blood vessel regeneration as demonstrated by the increasing interest dedicated to this field. This review is focused on the most relevant and recent studies concerning vascular tissue engineering for small diameter blood vessel applications. Specifically, the present work reviews research on the development of tissue-engineered vascular grafts made of decellularized matrices and natural and/or biodegradable synthetic polymers and their realization without scaffold.

scholarly journals Various Digestion Protocols Within Microplastic Sample Processing—Evaluating the Resistance of Different Synthetic Polymers and the Efficiency of Biogenic Organic Matter Destruction

2020 ◽  
Vol 8 ◽  
Author(s):  
Felix Pfeiffer ◽  
Elke Kerstin Fischer
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Matter ◽  
Polyethylene Terephthalate ◽  
Sodium Hypochlorite ◽  
Temperature Increase ◽  
Synthetic Polymers ◽  
Special Focus ◽  
Hard Tissue ◽  
Oxidizing Agents ◽  
Project Objectives

The digestion of biogenic organic matter is an essential step of sample preparation within microplastic analyses. Organic residues hamper the separation of polymer particles especially within density separation or polymer identification via spectroscopic and staining methods. Therefore, a concise literature survey has been undertaken to identify the most commonly applied digestion protocols with a special focus on water and sediments samples. The selected protocols comprise different solutions, concentrations, and reaction temperatures. Within this study we tested acids (nitric acid and hydrochloric acid), bases (sodium hydroxide and potassium hydroxide), and oxidizing agents [hydrogen peroxide, sodium hypochlorite and Fenton's reagent (hydrogen peroxide 30% in combination with iron(II)sulfate 0.27%)] at different concentrations, temperature levels, and reaction times on their efficiency of biogenic organic matter destruction and the resistance of different synthetic polymers against the applied digestion protocols. Tests were carried out in three parallels on organic material (soft tissue—leaves, hard tissue—branches, and calcareous material—shells) and six polymers (low-density polyethylene, high-density polyethylene, polypropylene, polyamide, polystyrene, and polyethylene terephthalate) in two size categories. Before and after the application of different digestion protocols, the material was weighed in order to determine the degree of digestion efficiency and polymer resistance, respectively. The efficiency of organic matter destruction is highly variable. Calcareous shells showed no to very low reaction to oxidizing agents and bases, but were efficiently dissolved with both tested acids at all concentrations and at all temperatures. Soft and hard tissue were most efficiently destroyed by sodium hypochlorite. However, the other reagents can also have good effects, especially by increasing the temperature to 40–50°C. The additional temperature increase to 60–70°C showed a further but less effective improvement, compared to the initial temperature increase. The resistance of tested polymer types can be rated as good except for polyamide and polyethylene terephthalate. Increasing the concentrations and temperatures, however, results in accelerated degradation of all polymers. This is most evident for polyamide and polyethylene terephthalate, which show losses in weight between 15 and 100% when the digestion temperature is increased. This effect is most pronounced for polyamide in the presence of acids and for polyethylene terephthalate digested with bases. As a concluding recommendation the selection of the appropriate digestion method should be specifically tested within initial pre-tests to account for the specific composition of the sample matrix and the project objectives.

scholarly journals Leaf wax <i>n</i>-alkanes in modern plants and topsoils from eastern Georgia (Caucasus) – implications for reconstructing regional paleovegetation

2017 ◽  
Author(s):  
Marcel Bliedtner ◽  
Imke K. Schäfer ◽  
Roland Zech ◽  
Hans von Suchodoletz
Keyword(s):  
Regional Scale ◽  
Chemical Degradation ◽  
Vegetation Types ◽  
Terrestrial Plants ◽  
Caucasus Region ◽  
Leaf Wax ◽  
South Eastern Europe ◽  
Southern Caucasus ◽  
Physical And Chemical ◽  
Long Chain

Abstract. Long-chain n-alkanes became increasingly used for paleoenvironmental studies during the last years as they have the great potential to reconstruct past changes in vegetation and climate. They mostly originate from leaf waxes of higher terrestrial plants, are relatively resistant against physical and chemical degradation and can thus serve as valuable biomarkers that are preserved in various sedimentary archives for at least millennial timescales. However, before any robust interpretation of the long-chain n-alkane patterns in sedimentary archives, reference samples from modern vegetation and topsoil material should be investigated at a regional scale. Apart from Central and South-Eastern Europe, such systematic regional studies on modern plant and topsoil material are still largely lacking. To test the potential of leaf wax derived n-alkane patterns for paleoenvironmental studies in the semi-humid to semi-arid southern Caucasus region, we investigated the influence of different vegetation types on the leaf wax n-alkane signal in modern plants and topsoil material (0–5 cm) from eastern Georgia. We sampled (i) sites with grassland that included steppe, cultivated grassland and meadows, and (ii) sites that are dominated by deciduous hornbeam forests. The n-alkane results show distinct and systematic differences between samples from sites with the different vegetation types: n-alkanes derived from sites with grassland are mainly dominated by C31, while n-alkanes derived from sites with deciduous trees show high abundances of C29. Thus, chain-length ratios allow to discriminate between these two different vegetation types and have a great potential when used for regional paleoenvironmental reconstructions. As degradation of organic matter can affect the leaf wax n-alkane distribution, we further present an updated end-member model that includes our results, accounts for degradation effects and enables semi-quantitative reconstruc-tions of past vegetation changes in the southern Caucasus region.

scholarly journals Qualitative Assessment of Effects of Encroachment on Water Resources of Agba Dam, Ilorin Nigeria

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
O.S Oladeji ◽  
R.A Olaoye ◽  
I.B Abioye
Keyword(s):  
Water Quality ◽  
Water Resources ◽  
Water Samples ◽  
Anthropogenic Activities ◽  
Qualitative Assessment ◽  
Rapid Urbanization ◽  
Aquatic Life ◽  
Iron Copper ◽  
High Population Growth ◽  
Physical And Chemical

The city of Ilorin in Nigeria has experienced high population growth and rapid urbanization. Agba Dam is one of the major sources of potable water in Ilorin, and currently being threatened by anthropogenic induced encroachment activities, with potential for significant derogatory effects on its quality. Therefore, this paper assesses the qualitative impact of encroachment on the water resources regime of Agba Dam, Ilorin, Nigeria. Field survey was carried out to scope proximal anthropogenic activities and to delineate historical as well as current extent of the encroachment area of the dam. Representative water samples were collected from locations within the dam catchment, and subsequently analyzed for alkalinity, dissolved carbondioxide, chloride, total iron, copper, sulphate, colour, calcium, dissolved oxygen and turbidity. In addition, historical physical and chemical data of water samples obtained from the dam were also acquired, and analyzed to determine temporal variation in the quality. The results show a reduction of 0.89 km2 or 63% in the historical buffer boundary of the dam. The values of the measured physico-chemical parameters were generally similar to that obtained for the historical values and therefore suggest limited impact of the anthropogenic activities on the water quality. However, slight increases were observed in the measured concentrations of the alkalinity, dissolved carbondioxide, chloride, iron, copper and sulphate, and this indicates possibilities of water quality alteration, with potential consequences for ecosystem and aquatic life if the trend is unabated.

scholarly journals Fire - mechanical behaviour of sandwich composite beam

2020 ◽  
pp. 22-26
Author(s):  
Tran Van Luan, Le Minh Tien Tran
Keyword(s):  
Mechanical Behaviour ◽  
Sandwich Beam ◽  
Extreme Temperature ◽  
Chemical Degradation ◽  
Sandwich Composite ◽  
Composite Sandwich ◽  
Materials Used ◽  
Marine Applications ◽  
Sandwich Materials ◽  
Physical And Chemical

We have analyzed the fire-mechanical behaviour of sandwich composite materials used in marine applications, as a function of the combustion time. In this light, sandwich beam samples are analyzed in terms of fire resistance kinetic and of post-combustion mechanical strength. We have shown that the materials undergo a strong degradation during 100 s of fire exposure at 750 ° C and this degradation is linked to the top skin. Finally, a finite element modelling work is being developed to predict the thermal behavior of composite sandwich materials; this modelling must include all thermal, physical and chemical degradation processes in order to realistically report resistance of materials in extreme temperature environment.

scholarly journals Microbial Degradation of Plastics and Approaches to Make it More Efficient

Microbiology ◽  
2021 ◽  
Vol 90 (6) ◽  
pp. 671-701
Author(s):  
I. B. Kotova ◽  
Yu. V. Taktarova ◽  
E. A. Tsavkelova ◽  
M. A. Egorova ◽  
I. A. Bubnov ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Microbial Degradation ◽  
Microscopic Fungi ◽  
Slow Process ◽  
Plastic Pollution ◽  
Degradation Processes ◽  
Worldwide Production ◽  
Plastic Degradation

Abstract— The growing worldwide production of synthetic plastics leads to increased amounts of plastic pollution. Even though microbial degradation of plastics is known to be a very slow process, this capacity has been found in many bacteria, including invertebrate symbionts, and microscopic fungi. Research in this field has been mostly focused on microbial degradation of polyethylene, polystyrene, and polyethylene terephthalate (PET). Quite an arsenal of different methods is available today for detecting processes of plastic degradation and measuring their rates. Given the lack of generally accepted protocols, it is difficult to compare results presented by different authors. PET degradation by recombinant hydrolases from thermophilic actinobacteria happens to be the most efficient among the currently known plastic degradation processes. Various approaches to accelerating microbial plastic degradation are also discussed.

Enzymatically Degradable Synthetic Polymers

1995 ◽  
Vol 394 ◽  
Author(s):  
Wen Shao ◽  
Kam W. Leong
Keyword(s):  
Interfacial Polymerization ◽  
Controlled Drug Delivery ◽  
Gel Permeation Chromatography ◽  
Synthetic Polymers ◽  
Complex Coacervation ◽  
Terephthaloyl Chloride ◽  
Carbon Backbone ◽  
Gel Permeation ◽  
Charged Component ◽  
Diaminopropionic Acid

AbstractComplex coacervation is an appealing method of microencapsulating delicate proteins for controlled drug delivery. Natural polyelectrolytes, such as collagen, gelatin, hyaluronic acid, and chondroitin sulfate, are popular choices for formulating the microspheres. For advantage of versatility, synthetic systems are attractive. Typical synthetic polyelectrolytes are composed of a carbon-carbon backbone that is nonbiodegradable. To design synthetic polyelectrolytes that are biodegradable, we synthesized diamines containing dipeptide or tripeptide sequences that are enzymatically degradable. The enzymatically degradable linkages comprised gly-phe, gly-phe-phe, or gly-gly-phe, and lysine and 2,3-diaminopropionic acid co-monomers served as the charged component. Using an interfacial polymerization technique, these monomers were condensed with diacyl chlorides, including succinyl, adipoyl, or terephthaloyl chloride to form polyamides. Results of gel permeation chromatography and ninhydrin assays showed that the polymers degraded in PBS containing α-chymotrypsin.

The structure and composition of macrozoobenthos community in varying water qualities in Kalibaru Waters, Bengkulu, Indonesia

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Lilisti LILISTI ◽  
Zamdial ZAMDIAL ◽  
Dede Hartono ◽  
Bieng Brata ◽  
Marulak Simarmata
Keyword(s):  
Human Activities ◽  
Aquatic Ecosystem ◽  
Chemical Parameters ◽  
Aquatic Life ◽  
Physical And Chemical Parameters ◽  
Ecological Threshold ◽  
Medium Level ◽  
The Government ◽  
Physical And Chemical

Abstract. Lilisti, Zamdial, Hartono D, Brata B, Simarmata M. 2021. The structure and composition of macrozoobenthos community in varying water qualities in Kalibaru Waters, Bengkulu, Indonesia. Biodiversitas 22: 106-112. Various human activities affect the quality of the aquatic ecosystem that can be assessed by measuring the physical, chemical, and biological parameters of the waters and sediments. This is the case of Kalibaru Waters, Bengkulu, Indonesia which shows changes in the estuary and marine ecosystems due to the cut-off of the main river around the area for the development of roads and bridges. The objective of this study was to analyze the quality of the waters and substrate, and the structure of the macrozoobenthos community as a bioindicator at the Kalibaru Waters. A survey was carried out in four stations, which was purposively selected based on human activities around the waters. Data collected included the physical and chemical parameters, and the diversity and density of macrozoobenthos species. The density of macrozoobenthos species was analyzed for summed dominance ratio (SDR), diversity (H'), homogeneity (E), and dominance (D) indices. The results showed that the physical and chemical parameters of Kalibaru Waters were acceptable for aquatic life, however, the oil contents at two stations exceeded the ecological threshold. Analysis of the macrozoobenthos community as a bioindicator for water quality found that the diversity and homogeneity indices were at a medium level indicating an unstable community, while the dominant index remained low indicating that none of the species was dominant in the Kalibaru Waters. This information is needed as a reference for the government of Bengkulu Province to make appropriate policies and management decisions to maintain the quality of the aquatic ecosystem in Kalibaru Waters.

Sign in / Sign up

Export Citation Format

Share Document