Relevant bibliographies by topics / Plastic degradation

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Plastic degradation'

Author: Grafiati
Published: 4 June 2021
Last updated: 9 March 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Plastic degradation.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Plastic degradation"

1

Alvarez, Karl Vincent N., Regina Mae V. Bulaong, Eloisa Nher A. Hipolito, Jonard Jairo P. Reyes, Astrid Ayla E. Liberato, and Leslie Joy L. Diaz. "Assessment of the Degradability of Commercially-Available Biodegradable Plastic Utensils in Soil and UV." Key Engineering Materials 821 (September 2019): 359–65. http://dx.doi.org/10.4028/www.scientific.net/kem.821.359.

Full text
Abstract:
Biodegradable plastics are viewed as one of the most promising solutions to plastic waste dilemma due to its natural degradative properties. Fossil fuel-based polymers have been infused with bio-based additives (e.g. starch) and have been used to produce biodegradable plastic products such as bags and cutleries. While several studies have dealt with degradation of polymers with bio-based additives, there is work yet to be done on degradation of commercially-available biodegradable plastic products. Here we evaluate degradability upon exposure to soil incubation and UV of three common starch-based plastic utensil brands in the Philippines that claim biodegradability. Analysis of IR absorbance spectra of post-exposure samples indicated high propensity towards photodegradation. Furthermore, estimation of full degradation period confirmed the biodegradability of starch-amended plastics which were limited to two brands. The presence of 19.22% and 24.18% starch in the plastic showed complete decomposition period of 156 and 92 days, respectively. This is a significant improvement over poor degradability exhibited by conventional plastics which often takes 450 to 1000 years. The reduction of degradation time through starch incorporation may prove to benefit manufacturers in fabricating more environmentally-friendly plastic products in the future.
APA, Harvard, Vancouver, ISO, and other styles
2

Banerjee, Risav, and Trisha Bhattacharya. "Degradation of synthetic polymers: Microbial approach." Indian Journal of Microbiology Research 9, no. 1 (April 15, 2022): 9–13. http://dx.doi.org/10.18231/j.ijmr.2022.002.

Full text
Abstract:
A synthetic polymer is a plastic, which is having wide applications in our day-to-day life. The packaging industries, agriculture, cosmetics, etc. Plastics are not easily degradable, it takes 1000 years to degrade a plastic or even more than that. The pollution caused by plastic is not only because of the waste disposal method but it is also because it releases carbon dioxide and dioxins while burning. Plastics are considered a threat to the environment as they are not easily degradable. Our review is based on the microbial approach for plastic degradation. The waste management method being used for plastic disposal is not effective enough. Nowadays biodegradable polymers are also being used as they are more easily degradable compared to synthetic polymers. The bacteria and fungi degrade most of the organic and inorganic components like starch, lignin, cellulose, and hemicelluloses.
APA, Harvard, Vancouver, ISO, and other styles
3

Artru, Maxime, and Antoine Lecerf. "Slow degradation of compostable plastic carrier bags in a stream and its riparian area." Annales de Limnologie - International Journal of Limnology 55 (2019): 18. http://dx.doi.org/10.1051/limn/2019017.

Full text
Abstract:
There is no place on Earth where plastic debris could not be found. Impacts of plastics on aesthetics, biota and ecosystems are dependent on how long plastic items last, and what degradation products are released, in recipient environments. As bio-based plastics tend to replace petroleum-based plastics in everyday life, it is important to upgrade knowledge on the degradation of new polymers in natural environments. Single-use plastic carrier bags are nowadays made of bio-plastics certified as biodegradable and compostable. It is unclear, however, whether claims of biodegradability and compostability can be taken as evidence of rapid degradation of plastic bags outside recycling/composting facilities. This study sought to provide quantified information about the degradation of compostable plastic carrier bags in streams and riparian zones. We found that plastic samples enclosed in different types of mesh bags lost weight at extremely slow rates, albeit significant when submerged in a stream. 95% of initial plastic mass remained after 77 days spent in water whereas alder leaf litter allowed to decompose under the same condition had completely disappeared before the end of the study. Determination of respiration rate and invertebrate abundance in plastic samples showed a greater decomposer activity in the stream than in the riparian environment. However, biotically-mediated degradation by decomposers was probably overridden by dissolution processes in mediating plastic mass loss. Our findings suggest that mismanaged plastic carrier bags could impact recipient ecosystems even when they are claimed as biodegradable or compostable.
APA, Harvard, Vancouver, ISO, and other styles
4

Kotova, I. B., Yu V. Taktarova, E. A. Tsavkelova, M. A. Egorova, I. A. Bubnov, D. V. Malakhova, L. I. Shirinkina, T. G. Sokolova, and E. A. Bonch-Osmolovskaya. "Microbial Degradation of Plastics and Approaches to Make it More Efficient." Microbiology 90, no. 6 (November 2021): 671–701. http://dx.doi.org/10.1134/s0026261721060084.

Full text
Abstract:
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.
APA, Harvard, Vancouver, ISO, and other styles
5

Hassan, Sidra, and Ihsan Ul Haq. "Pervasive Pollution Problems Caused by Plastics and its Degradation." International Journal of Online and Biomedical Engineering (iJOE) 15, no. 10 (June 27, 2019): 29. http://dx.doi.org/10.3991/ijoe.v15i10.10873.

Full text
Abstract:
We are living in a period of time where gaining access to clean water, food and even air is almost impossible. Everything on the planet Earth is contaminated in one form or another. Not only humans but all the creatures of the planet are under constant threat from at least one of the forms of pollution. Like other forms of pollution, plastic pollution is also a huge and mounting problem and it demands a similarly ambitious and influential solution. As ‘human-caused climate change’ received so much attention, this issue also needs the same consideration and it should be approached in the same way. Plastic pollution is killing our planet! It’s choking our oceans by making plastic gyres, entangling marine animals, poisoning our food and water supply, and ultimately inflicting havoc on the health and well-being of humans and wildlife globally. With the exception of a small amount that has been incinerating, virtually every piece of plastic that was ever made in the past still exists in one form or another. And since most of the plastics don’t biodegrade in any meaningful sense, all that plastic waste could exist for hundreds or even thousands of years. If plastic production isn’t circumscribed, plastic pollution will be disastrous and will eventually outweigh fish in oceans. It’s time to think about the plastics, banning the single-use plastics, thinking about the recycling and going towards the zero-waste concept. This paper covers the reviews about current research on the plastic disasters by plastic industry and biodegradation of the conventional synthetic plastics by different microorganisms and major concerns related to ocean plastic pollution
APA, Harvard, Vancouver, ISO, and other styles
6

Lear, G., S. D. M. Maday, V. Gambarini, G. Northcott, R. Abbel, J. M. Kingsbury, L. Weaver, J. A. Wallbank, and O. Pantos. "Microbial abilities to degrade global environmental plastic polymer waste are overstated." Environmental Research Letters 17, no. 4 (March 15, 2022): 043002. http://dx.doi.org/10.1088/1748-9326/ac59a7.

Full text
Abstract:
Abstract Internationally, the environmental damage caused by the improper disposal of approximately 100 Mt of plastic waste per annum is of growing concern. Attempts to address this issue have generated many hundreds of scientific studies announcing the discovery of novel plastic-degrading microorganisms and their respective enzymes. On closer inspection, however, evidence remains sparse for the microbial degradation of most of the plastic polymers produced globally. We systematically surveyed the international literature to confirm how many microorganisms proposed to degrade plastics (n = 664) cause substantial (i.e. ⩾20% mass) losses of virgin polymer, rather than losses of plastic additives, filler, and/or shedding of polymer micro-fragments. We noted where degradation was only demonstrated for artificially aged polymer since physicochemical ageing procedures increase the abundance of monomers and oligomers such that they may be degraded by microbial activity. Additionally, artificial ageing may introduce functional groups to the polymer backbone, creating more locations susceptible to microbial degradation than would otherwise occur in the environment. We identified multiple studies demonstrating the effective microbial degradation of heterochain plastic polymers such as polylactic acid, polycaprolactone and polyethylene terephthalate (i.e. polymers containing elements other than carbon in the backbone structure). However, in the literature, we find no evidence for the substantial degradation of unadulterated polyethylene, polypropylene, polystyrene or polyvinyl chloride, homochain polymers which represent the overwhelming majority of global plastics production. Current research demonstrates that the pre-treatment of plastics with elevated temperature or UV-light may speed physicochemical plastic degradation, with valuable applications for downstream microbial processing. However, evidence for the microbial degradation of most plastic polymers in current circulation is lacking. We outline simple criteria that should be met before announcing the microbial degradation of plastic polymers. We hope this may help to address largely unsubstantiated expectations that microorganisms can degrade many plastic polymers in situ.
APA, Harvard, Vancouver, ISO, and other styles
7

Zhang, Haigang, Yilin Hou, Wenjin Zhao, and Hui Na. "Control Strategies of Plastic Biodegradation through Adjusting Additives Ratios Using In Silico Approaches Associated with Proportional Factorial Experimental Design." International Journal of Environmental Research and Public Health 19, no. 9 (May 6, 2022): 5670. http://dx.doi.org/10.3390/ijerph19095670.

Full text
Abstract:
Plastics, as a polymer material, have long been a source of environmental concern. This paper uses polystyrene plastics as the research object, and the relative contribution of each component of plastic additives to plastic degradation is screened using the molecular dynamics method. The factorial experimental design method is combined with molecular dynamics simulation to adjust the additive composition scheme, analyze the mechanism of interaction between the additive components, and select the plastic additive combination that is most readily absorbed and degraded by microorganisms. Seven different types of plastic additives, including plasticizers, antioxidants, light and heat stabilizers, flame retardants, lubricants, and fillers, are chosen as external stimuli affecting the biodegradability of plastics. Using molecular dynamics simulation technology, it is demonstrated that plastic additives can promote the biodegradability of plastics. The factorial experimental design analysis revealed that all plastic additives can promote plastic biodegradation and plasticizer is the most favorable factor affecting plastic degradation, that hydrophobicity interactions are the primary reason for enhancing plastic degradation, and that screening No. 116–45 (plasticizer A, light stabilizer C, flame retardant E) is the most advantageous combination of biodegradable plastic additives. The plastic biodegradation effect regulation scheme proposed in this study is based on optimizing the proportion of additive components. To continue research on aquatic biodegradable plastics, the optimal combination of plastic components that can be absorbed and degraded by microorganisms is recommended.
APA, Harvard, Vancouver, ISO, and other styles
8

Ekanayaka, Anusha H., Saowaluck Tibpromma, Donqin Dai, Ruifang Xu, Nakarin Suwannarach, Steven L. Stephenson, Chengjiao Dao, and Samantha C. Karunarathna. "A Review of the Fungi That Degrade Plastic." Journal of Fungi 8, no. 8 (July 25, 2022): 772. http://dx.doi.org/10.3390/jof8080772.

Full text
Abstract:
Plastic has become established over the world as an essential basic need for our daily life. Current global plastic production exceeds 300 million tons annually. Plastics have many characteristics such as low production costs, inertness, relatively low weight, and durability. The primary disadvantage of plastics is their extremely slow natural degradation. The latter results in an accumulation of plastic waste in nature. The amount of plastic waste as of 2015 was 6300 million tons worldwide, and 79% of this was placed in landfills or left in the natural environment. Moreover, recent estimates report that 12,000 million tons of plastic waste will have been accumulated on the earth by 2050. Therefore, it is necessary to develop an effective plastic biodegradation process to accelerate the natural degradation rate of plastics. More than 400 microbes have been identified as capable of plastic degradation. This is the first paper of the series on plastic-degrading fungi. This paper provides a summary of the current global production of plastic and plastic waste accumulation in nature. A list is given of all the plastic-degrading fungi recorded thus far, based on the available literature, and comments are made relating to the major fungal groups. In addition, the phylogenetic relationships of plastic-degrading fungi were analyzed using a combined ITS, LSU, SSU, TEF, RPB1, and RPB2 dataset consisting of 395 strains. Our results confirm that plastic-degrading fungi are found in eleven classes in the fungal phyla Ascomycota (Dothideomycetes, Eurotiomycetes, Leotiomycetes, Saccharomycetes, and Sordariomycetes), Basidiomycota (Agaricomycetes, Microbotryomycetes, Tremellomycetes, Tritirachiomycetes, and Ustilaginomy-cetes), and Mucoromycota (Mucoromycetes). The taxonomic placement of plastic-degrading fungal taxa is briefly discussed. The Eurotiomycetes include the largest number of plastic degraders in the kingdom Fungi. The results presented herein are expected to influence the direction of future research on similar topics in order to find effective plastic-degrading fungi that can eliminate plastic wastes. The next publication of the series on plastic-degrading fungi will be focused on major metabolites, degradation pathways, and enzyme production in plastic degradation by fungi.
APA, Harvard, Vancouver, ISO, and other styles
9

Reddy, G. Koteswara, and Yarrakula Kiran. "A Theoretical Mechanism in the Degradation of Polyolefin Plastic Waste Using Phytochemical Oxidation Process." Journal of Solid Waste Technology and Management 45, no. 4 (November 1, 2019): 468–78. http://dx.doi.org/10.5276/jswtm/2019.468.

Full text
Abstract:
The purpose of this study is to provide a theoretical mechanism during the degradation of polyolefin plastic waste using phytochemicals. Existing degradation (physical, chemical and biological) methods are ineffective, expensive and notably time consuming during the degradation of polyolefin plastics. During the phytochemical degradation process, initially, polyolefin plastic is oxidized and converted into the hydrophilic nature by photo-oxidation. Thereafter, phyto phenols can be used to cleave the main chains of polyolefin plastics, thereby, small molecular hydrocarbons are formed such as oligomers, monomers and dimers. During this process, primary products like all the reactive hydroperoxides and free radicals might be produced and lead to further chain cleavage via peroxide cross linkage. Besides, the consequences of plastic chain cleavage make the product apparently more susceptible to biodegradation. The phytochemical based degradation mechanism is useful for the researchers in the direction towards plastic hazards reduction and management on the earth's environment.
APA, Harvard, Vancouver, ISO, and other styles
10

Khaldoon, Shahad, Japareng Lalung, Umrana Maheer, Mohamad Anuar Kamaruddin, Mohd Firdaus Yhaya, Eman S. Alsolami, Hajer S. Alorfi, Mahmoud A. Hussein, and Mohd Rafatullah. "A Review on the Role of Earthworms in Plastics Degradation: Issues and Challenges." Polymers 14, no. 21 (November 7, 2022): 4770. http://dx.doi.org/10.3390/polym14214770.

Full text
Abstract:
Recently, the contribution of earthworms to plastic degradation and their capability to swallow smaller plastic fragments, known as microplastics, has been emphasized. The worm physically changes the size of microplastics and enhances microbial activities to increase the possibility of degradation. However, no research has shown that earthworms can chemically degrade microplastics to an element form, CO2 or H2O. In this review, previous research has been thoroughly explored to analyse the role that earthworms could play in plastic degradation in the soil. Earthworms can significantly affect the physical characteristics of plastics. However, earthworms’ abilities to chemically degrade or change the chemical structure of plastics and microplastics have not been observed. Additionally, earthworms exhibit selective feeding behaviour, avoiding areas containing a high plastics concentration and rejecting plastics. Consequently, earthworms’ abilities to adapt to the microplastics in soil in the environment can cause a problem. Based on this review, the challenges faced in earthworm application for plastic degradation are mostly expected to be associated with the toxicity and complexity of the plastic material and environmental factors, such as the moisture content of the soil and its temperature, microbial population, and feeding method.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Plastic degradation"

1

RIZZO, Marzia. "Common plastic degradation in coastal environments." Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2486762.

Full text
Abstract:
In the environment, the main factors influencing the degradation of plastics are the type of polymer, abiotic processes and biotic factors. According to the literature, the environment where plastic waste is subjected to environmental conditions that favor its degradation and the production of microplastics seems to be the coastal one. To increase knowledge on the degradation of plastics in this environment, in situ experiments were conducted in sub coastal environments to test the degradation of six commonly used types of plastics and the possible factors responsible for the degradation were investigated. The degradation in the urban air environment has also been studied and compared with that in the coastal environment. The types of plastic used were polystyrene (PS), polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), polyethylene terephthalate (PET) and polyvinyl chloride (PVC). The sub-environments selected were a) a lagoon, b) a port environment and c) a fluvial environment near the mouth. They have been identified in Italy, in Goro (Ferrara) and in the area of Siracusa. Testing racks were built to allow the exposure of all types of plastics in the form of strips. They were suitably installed in the Goro lagoon and in the “Porto Piccolo” of Siracusa at intertidal and subtidal depths, at the Ciane River in Siracusa, in semi-floating and submerged conditions and on a terrace of a building at Siracusa. Sampling of the plastic strips was performed after 4, 8, 12, 16, 20, 28 and 36 weeks of exposure in each environment. At each sampling time point, total mass change and mass change after washing with hydrochloric acid were measured; from week 4 to week 28 samples chlorophyll a accumulation were measured. The 12- and 28-week exposure samples were also observed using SEM and were subjected to leaching testing. Plastic strips exposed for 28 weeks in the lagoon and port environments were subjected to dissolution by acid attacks. Subsequently, factorial ANOVA was performed to assess the influence of plastic type, depth zonation, and deployment time, on apparent plastic mass change, biofilm mass accumulation, and Chla accumulation. The study showed that the rate of degradation and the type of degradation strongly depend on the environment to which the plastics were exposed. Greater UV radiation, higher temperatures and the absence of fouling are the causes that have led to greater degradation in the air environment than in the aquatic environment. The aquatic environments that caused the greatest degradation is the port one, followed by the lagoon one and finally the river one. In the latter, however, no significant degradation was found. The agents that contributed to the degradation are many: exposure to UV rays, environmental temperature, water salinity, accumulation of fouling, oxygen availability, hydrodynamic energy. Beyond UV radiation, considered the most influential factor on degradation, fouling also played an important effect. In fact, it mainly carried out a role by shielding the plastic from UV radiation. The degradation was also influenced by the depth of deployment. In intertidal/semi-floating conditions, in fact, due to the greater UV radiation, the greater thermal stress and the greater hydrodynamic energy, the plastic strips have undergone greater degradation compared to the subtidal/submerged conditions. The type of plastic also affected the rate of degradation. PS was the one most subject to degradation in all environments, showing mostly fragmentation. In the air environment, there was a greater degradation for PP, PET and PVC plastics and minimal degradation for LDPE and HDPE. In the lagoon and port environment, on the other hand, there was a greater degradation for PET and PVC and gradually decreasing for LDPE, HDPE, and PP. In the river environment, even if it was present differentiated by type of plastic, the degradation was not found significantly.
APA, Harvard, Vancouver, ISO, and other styles
2

Sykes, Katharine Ellen. "Crystallization and degradation of a biodegradable plastic - polyhydroxybutyrate." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336867.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Li, Junhong. "Elastic - plastic interfacial crack problems." Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297517.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Davenport, James Charles William. "Mixed mode elastic-plastic fracture." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357788.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Stewart, Robert A. "Analytical studies of the degradation of cellulose nitrate artefacts." Thesis, University of Strathclyde, 1997. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21503.

Full text
Abstract:
The deterioration of cellulose nitrate artefacts in museum and art collections is a complex problem facing conservators and conservation scientists. This study has looked at several aspects of the degradation by analysing artefacts and model samples. Initial work concentrated on a survey of a collection of artefacts, many of which showed active degradation, by visual inspection and FTTR spectroscopy. A more thorough analysis of the artefacts was carried out, using ion chromatography, xray fluorescence spectroscopy and atomic absorption spectroscopy, to identify compositional differences between samples, which may relate to degradation. The results of these studies suggested that residual sulphate in the plastics is a cause of increased degradation. The presence of oxalate in degraded artefacts also indicated that chain scission is occurring during deterioration. Later work using gel permeation chromatography confirmed this. Work has also involved the use of accelerated ageing tests to study the effect of sulphate in the degradation and also the influence of inorganic fillers, iron and humidity. It has been concluded that the degradation of cellulose nitrate artefacts is dependent on the presence of sulphate and humidity. The process is diffusion controlled which indicates that loss of plasticiser is a vital factor. This work also suggests simple procedures that can be used to assess an artefact's stability.
APA, Harvard, Vancouver, ISO, and other styles
6

Viesca, Lobaton Gabriel D. "Fatigue crack propagation in plastic fields." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301842.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

McMillan, Alan Robert. "Environmental degradation of glass reinforced polyesters in the wastewater treatment industry." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362912.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Alin, Jonas. "Migration from plastic food packaging during microwave heating." Doctoral thesis, KTH, Polymerteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96078.

Full text
Abstract:
Microwave heating of food has increased rapidly as a food processing technique. This increases the concern that chemicals could migrate from food packaging to food. The specific effect of microwave heating in contrast to conventional heating on overall and specific migration from common plastic food storage boxes was studied in this work. The purpose was especially to determine the interaction effects of different plastics in contact with different types of foods during microwave heating. The study focused on polycarbonate (PC), poly(ethylene terephthalate) (PET), polypropylene homo-polymer (PP), co-polymer (PP-C) and random co-polymer (PP-R) packages. The migration determinations were evaluated at controlled times and temperatures, using a MAE device. The migrants were analyzed by GC-MS and HPLC. ESI-MS was evaluated as a new tool for migration determinations. Food/food simulant absorption and changes in degree of crystallinity during heating were also followed. Significant degradation of antioxidants Irgafos 168 and Irganox 1010 in PP packages occurred during microwave heating of the packages in food simulants containing ethanol, resulting in the formation of antioxidant degradation products. Degradation of PC by Fries chain rearrangement reaction leading to formation of 9,9-dimethylxanthene, and transesterification of PET leading to formation of diethyl terephthalate, were also observed after microwave heating the packages in ethanol and 90/10 isooctane/ethanol. These reactions were not observed during conventional heating of the packages at the same temperature, or after microwave heating of the packages in liquid food (coconut milk). The microwave heating also significantly increased the migration of cyclic oligomers from PET into ethanol and isooctane at 80 °C. Migration of compounds into coconut milk was slightly lower than calculated amounts using the EU mathematical model to predict migration of additives into foodstuffs. The results thus show that the use of ethanol as a fat food simulant during microwave heating can lead to a significant overestimation of migration as well as degradation of polymer or the incorporated additives. Some other detected migrants were dimethylbenzaldehyde, 4-ethoxy-ethyl benzoate, benzophenone, m-tert-butyl phenol and 1-methylnaphthalene. All identified migrants with associated specific migration limit (SML) values migrated in significantly lower amounts than the SML values during 1 h of microwave heating at 80 °C. The antioxidant diffusion coefficients in PP and PP co-polymers showed larger relative differences than the corresponding degrees of crystallinity in the same polymers and PP-R showed by far the fastest migration of antioxidants.
Mikrovågsuppvärmning av mat har ökat markant under de senaste åren. Detta ökar risken för att ämnen i plast migrerar från matförpackningar till mat. Den specifika effekten av mikrovågsvärmning i kontrast till konventionell värmning på total och specifik migrering från vanliga matförvaringslådor av plast studerades i denna avhandling. Syftet var i huvudsak att bestämma interaktionseffekter mellan olika typer av plaster och olika typer av mat under mikrovågsvärmning. Studien fokuserades på förpackningar av polykarbonat (PC), polyetentereftalat (PET), polypropylen homopolymer (PP), copolymer (PP-C) och random copolymer (PP-R). Migreringstesterna utfördes under kontrollerade tider och temperaturer genom att använda MAE. Migranterna analyserades med hjälp av GC-MS och HPLC. ESI-MS-analys utvärderades också som ny analysmetod för migreringstester. Absorption av mat- och matsimulanter samt förändringar i kristallinitetsgrad följdes också. Signifikant nedbrytning av antioxidanterna Irgafos 168 och Irganox 1010 i PP-förpackningar inträffade under mikrovågsvärmning av förpackningarna i etanol-innehållande matsimulanter, vilket resulterade i bildning av nedbrytningsprodukter från antioxidanterna. Nedbrytning av PC genom en Fries omfördelningsreaktion, vilket orsakade bildning av 9,9-dimetylxanten, samt transesterifikation av PET, vilket orsakade bildning av dietyltereftalat, observerades också efter mikrovågsvärmning av förpackningarna i etanol och 90/10 isooktan/etanol. Dessa reaktioner observerades ej efter konventionell värmning av förpackningarna under samma temperatur och ej heller efter mikrovågsvärmning av förpackningarna i riktig mat (kokosmjölk). Mikrovågsvärmningen ökade också betydelsefullt migrering av cykliska oligomerer från PET till etanol och isooktan under 80 °C. Specifika ämnens migrering till kokosmjölk var alla något lägre än migreringsvärden beräknade m. h. a. EU's officiella matematiska modell för förutsägelse av migrering från matförpackningar till mat. Dessa resultat visar att användandet av etanol som matsimulant för fet mat under mikrovågsvärmning kan leda till betydande överestimering av migrering, samt nedbrytning av polymer och additiv i polymeren. Andra detekterade migranter var till exempel dimetylbenzaldehyd, 4-etoxy-etylbenzoat, benzofenon, m-tertbutylfenol och 1-metylnaftalen. Alla identifierade migranter med tillhörande ‘specific migration limit’ (SML)-värden migrerade i betydelsefullt mindre mängder än ämnenas tillhörande SML-värden under 1 h mikrovågsvärmning under 80°C. Diffusionskoefficienterna för antioxidanterna i PP-förpackningarna visade större relativa skillnader än förpackningarnas motsvarande kristallinitetsgrader och migrering av antioxidanter var snabbast från PP-R.

QC 20120530

APA, Harvard, Vancouver, ISO, and other styles
9

Stelmashenko, Nadia. "Microstructural studies of plastic indentations at low loads." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390178.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Gregory, P. W. "Finite elastic-plastic deformations of highly anisotropic materials." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282601.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Plastic degradation"

1

Rosa, Maria I. De. Oxidative thermal degradation of PVC-derived fiberglass, cotton, and jute brattices and other mine materials: A comparison of toxic gas and liquid concentrations and smoke-particle characterization. Pittsburgh, Pa. (Cochrans Mill Rd., P.O. Box 18070, Pittsburgh 15236): U.S. Dept. of the Interior, Bureau of Mines, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

The great Pacific garbage patch. Minneapolis, Minnesota: ABDO Publishing Company, 2018.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

C, Portnoy Robert, ed. Medical plastics: Degradation resistance & failure analysis. Norwich, NY: Plastic Design Library, 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Chohan, Sukhvinder Kaur. Environmental degradation of polyethylene-based plastics. Birmingham: Aston University. Department ofChemical Engineering and Applied Chemistry, 1996.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

Conservation of plastics: Materials science, degradation and preservation. Amsterdam: Elsevier/Butterworth-Heinemann, 2008.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Shashoua, Yvonne. Conservation of plastics: Materials science, degradation and preservation. Amsterdam: Elsevier/Butterworth-Heinemann, 2008.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

Tsuji, Hideto. Degradation of poly (lactide)- based biodegradable materials. New York: Nova Science Publishers, 2008.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

Li, Zhiru. The degradation effects of pyrolysis liquids on metals, plastics and elastomers. Ottawa: National Library of Canada, 2001.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

Imielińska, Krystyna. Degradation and damage of advanced laminate polymer composites due to environmental effects and low velocity impact. Gdańsk: Politechnika Gdańska, 2005.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

E, Kamvouris John, and United States. National Aeronautics and Space Administration., eds. Penetration of carbon-fabric-reinforced composites by edge cracks during thermal aging. [Washington, DC]: National Aeronautics and Space Administration, 1994.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Plastic degradation"

1

Shahnawaz, Mohd, Manisha K. Sangale, and Avinash B. Ade. "Analysis of the Plastic Degradation Products." In Bioremediation Technology for Plastic Waste, 93–101. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7492-0_9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Singh, Garima, Sonal Yadav, Kanika Chowdhary, and Satyawati Sharma. "Role of Microbes in Plastic Degradation." In Recent Developments in Microbial Technologies, 281–99. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-4439-2_13.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Shahnawaz, Mohd, Manisha K. Sangale, and Avinash B. Ade. "In Situ Bioremediation Technology for Plastic Degradation." In Bioremediation Technology for Plastic Waste, 71–75. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7492-0_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Shahnawaz, Mohd, Manisha K. Sangale, and Avinash B. Ade. "Ex Situ Bioremediation Technology for Plastic Degradation." In Bioremediation Technology for Plastic Waste, 77–83. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7492-0_7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Cocca, Mariacristina, Francesca De Falco, Gennaro Gentile, Roberto Avolio, Maria Emanuela Errico, Emilia Di Pace, and Maurizio Avella. "Degradation of Biodegradable Plastic Buried in Sand." In Springer Water, 205–9. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-71279-6_28.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Parangi, Tarun, and Manish Kumar Mishra. "Photocatalytic Degradation of Plastic Polymer: A Review." In Re-Use and Recycling of Materials, 225–50. New York: River Publishers, 2022. http://dx.doi.org/10.1201/9781003339304-15.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Shahnawaz, Mohd, Manisha K. Sangale, and Avinash B. Ade. "Case Studies and Recent Update of Plastic Waste Degradation." In Bioremediation Technology for Plastic Waste, 31–43. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7492-0_4.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Parashar, Neha, and Subrata Hait. "Plastic Waste Management: Current Overview and Future Prospects." In Environmental Degradation: Challenges and Strategies for Mitigation, 471–94. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95542-7_22.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Li, Wai Chin, Hin Fung Tse, Ho Man Leung, and Ying Kit Yue. "Degradation of Plastic Waste in the Marine Environment." In Impact of Plastic Waste on the Marine Biota, 143–74. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-5403-9_8.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Siah, L. F. "Moisture-Driven Electromigrative Degradation in Microelectronic Packages." In Moisture Sensitivity of Plastic Packages of IC Devices, 503–22. Boston, MA: Springer US, 2010. http://dx.doi.org/10.1007/978-1-4419-5719-1_20.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Plastic degradation"

1

Xia, BoYi. "Potential Solution for Plastic Degradation-- Genetical Modification." In 2021 International Conference on Social Development and Media Communication (SDMC 2021). Paris, France: Atlantis Press, 2022. http://dx.doi.org/10.2991/assehr.k.220105.198.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Grissa, O., E. Baraketi, N. Khouja, T. Yahyaoui, S. Ismaïl, A. Benzarti, J. Hsinet, and A. Ben Jemaa. "Respiratory allergies to thermal degradation products of plastic." In ERS International Congress 2022 abstracts. European Respiratory Society, 2022. http://dx.doi.org/10.1183/13993003.congress-2022.3174.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Nizarudin, Salman, and B. Deepak. "Thermocatalytic degradation: Solution for plastic waste management in Kerala." In 2016 IEEE Region 10 Humanitarian Technology Conference (R10-HTC). IEEE, 2016. http://dx.doi.org/10.1109/r10-htc.2016.7906801.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Fukuzawa, I., S. Ishiguro, and S. Nanbu. "Moisture Resistance Degradation of Plastic LSIs by Reflow Soldering." In 23rd International Reliability Physics Symposium. IEEE, 1985. http://dx.doi.org/10.1109/irps.1985.362097.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Zeb Abbasi, Haleema, Umair Amjad, Bibi Saima Zeb, and Muhammad Hashim Ali Abbasi. "Critical Evaluation of Plastic waste remediation through Microbial Degradation." In 2021 Third International Sustainability and Resilience Conference: Climate Change. IEEE, 2021. http://dx.doi.org/10.1109/ieeeconf53624.2021.9668178.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Liu, Xinyue, and Finn Stirling. "Conditions for a Microbial Consortium for the Biological Degradation of Plastic Polymers." In The International Conference on Biomedical Engineering and Bioinformatics. SCITEPRESS - Science and Technology Publications, 2022. http://dx.doi.org/10.5220/0011195700003443.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Mead, Patricia F., Melody Burch, Patrick McCluskey, and F. G. Johnson. "Failure Analysis of Plastic Packaged GaAs and AlGaAs/GaAs LEDs." In ISTFA 1999. ASM International, 1999. http://dx.doi.org/10.31399/asm.cp.istfa1999p0173.

Full text
Abstract:
Abstract Failure and degradation mechanisms of plastic packaged LEDs that have been subjected to high levels of moisture, current bias, and elevated temperature conditions have been investigated and analyzed. The investigation included electrical characterization and a variety of failure analysis techniques including photoluminescence (PL), electroluminescence (EL), cathodoluminescence (CL), and environmental scanning electron microscopy (ESEM). Our results highlight the usefulness of simple screening techniques to monitor the quality of newly manufactured LED packages. Our results also indicate that for AlGaAs structures, degradation of the light output and electrical performance involves a complex interaction between temperature, relative humidity at the LED surface and voltage bias.
APA, Harvard, Vancouver, ISO, and other styles
8

Willems, F., and C. Bonten. "Influence of processing on the fiber length degradation in fiber reinforced plastic parts." In PROCEEDINGS OF THE REGIONAL CONFERENCE GRAZ 2015 – POLYMER PROCESSING SOCIETY PPS: Conference Papers. Author(s), 2016. http://dx.doi.org/10.1063/1.4965454.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Coscodan, Mihai. "The perspective of using soil microorganisms for degradation of non-recyclable plastic waste." In National Scientific Symposium With International Participation: Modern Biotechnologies – Solutions to the Challenges of the Contemporary World. Institute of Microbiology and Biotechnology, Republic of Moldova, 2021. http://dx.doi.org/10.52757/imb21.019.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Shirley, C. G., and M. S. De Guzman. "Moisture-induced gold ball bond degradation of polyimide-passivated devices in plastic packages." In Proceedings of IEEE International Reliability Physics Symposium. IEEE, 1993. http://dx.doi.org/10.1109/relphy.1993.283321.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Plastic degradation"

1

Beck, Aaron. NAPTRAM - Plastiktransportmechanismen, Senken und Interaktionen mit Biota im Nordatlantik / NAPTRAM - North Atlantic plastic transport mechanisms, sinks, and interactions with biota, Cruise No. SO279, Emden (Germany) – Emden (Germany), 04.12.2020 – 05.01.2021. Gutachterpanel Forschungsschiffe Bonn, 2021. http://dx.doi.org/10.3289/cr_so279.

Full text
Abstract:
The coastal and open oceans represent a major, but yet unconstrained, sink for plastics. It is likely that plastic-biota interactions are a key driver for the fragmentation, aggregation, and vertical transport of plastic litter from surface waters to sedimentary sinks. Cruise SO279 conducted sampling to address core questions of microplastic distribution in the open ocean water column, biota, and sediments. Seven stations were sampled between the outer Bay of Biscay and the primary working area south of the Azores. Additional samples were collected from surface waters along the cruise track to link European coastal and shelf waters with the open ocean gyre. Microplastic samples coupled with geochemical tracer analyses will build a mechanistic understanding of MP transport and its biological impact reaching from coastal seas to the central gyre water column and sinks at the seabed. Furthermore, floating plastics were sampled for microbial community and genetic analyses to investigate potential enzymatic degradation pathways. Cruise SO279 served as the third cruise of a number of connected research cruises to build an understanding of the transport pathways of plastic and microplastic debris in the North Atlantic from the input through rivers and air across coastal seas into the accumulation spots in the North Atlantic gyre and the vertical export to its sink at the seabed. The cruise was an international effort as part of the JPI Oceans project HOTMIC (“HOrizontal and vertical oceanic distribution, Transport, and impact of MICroplastics”) and the BMBF funded project PLASTISEA (‘Harvesting the marine Plastisphere for novel cleaning concepts’), and formed a joint effort of HOTMIC and PLASTISEA researchers from a range of countries and institutes.
APA, Harvard, Vancouver, ISO, and other styles
2

Oliynyk, Kateryna, and Matteo Ciantia. Application of a finite deformation multiplicative plasticity model with non-local hardening to the simulation of CPTu tests in a structured soil. University of Dundee, December 2021. http://dx.doi.org/10.20933/100001230.

Full text
Abstract:
In this paper an isotropic hardening elastoplastic constitutive model for structured soils is applied to the simulation of a standard CPTu test in a saturated soft structured clay. To allow for the extreme deformations experienced by the soil during the penetration process, the model is formulated in a fully geometric non-linear setting, based on: i) the multiplicative decomposition of the deformation gradient into an elastic and a plastic part; and, ii) on the existence of a free energy function to define the elastic behaviour of the soil. The model is equipped with two bonding-related internal variables which provide a macroscopic description of the effects of clay structure. Suitable hardening laws are employed to describe the structure degradation associated to plastic deformations. The strain-softening associated to bond degradation usually leads to strain localization and consequent formation of shear bands, whose thickness is dependent on the characteristics of the microstructure (e.g, the average grain size). Standard local constitutive models are incapable of correctly capturing this phenomenon due to the lack of an internal length scale. To overcome this limitation, the model is framed using a non-local approach by adopting volume averaged values for the internal state variables. The size of the neighbourhood over which the averaging is performed (characteristic length) is a material constant related to the microstructure which controls the shear band thickness. This extension of the model has proven effective in regularizing the pathological mesh dependence of classical finite element solutions in the post-localization regime. The results of numerical simulations, conducted for different soil permeabilities and bond strengths, show that the model captures the development of plastic deformations induced by the advancement of the cone tip; the destructuration of the clay associated with such plastic deformations; the space and time evolution of pore water pressure as the cone tip advances. The possibility of modelling the CPTu tests in a rational and computationally efficient way opens a promising new perspective for their interpretation in geotechnical site investigations.
APA, Harvard, Vancouver, ISO, and other styles
3

Stern, David, and Gadi Schuster. Manipulating Chloroplast Gene Expression: A Genetic and Mechanistic Analysis of Processes that Control RNA Stability. United States Department of Agriculture, June 2004. http://dx.doi.org/10.32747/2004.7586541.bard.

Full text
Abstract:
New potential for engineering chloroplasts to express novel traits has stimulated research into relevant techniques and genetic processes, including plastid transformation and gene regulation. This BARD-funded research dealt with the mechanisms that influence chloroplast RNA accumulation, and thus gene expression. Previous work on cpRNA catabolism has elucidated a pathway initiated by endonucleolytic cleavage, followed by polyadenylation and exonucleolytic degradation. A major player in this process is the nucleus-encoded exoribo-nuclease/polymerase polynucleotide phosphorylase (PNPase). Biochemical characterization of PNPase has revealed a modular structure that controls its RNA synthesis and degradation activities, which in turn are responsive to the phosphate (P) concentration. During the funding period, new insights emerged into the molecular mechanism of RNA metabolism in the chloroplast and cyanobacteria, suggesting strategies for improving agriculturally-important plants or plants with novel introduced traits.
APA, Harvard, Vancouver, ISO, and other styles
4

Whisler, Daniel, Rafael Gomez Consarnau, and Ryan Coy. Novel Eco-Friendly, Recycled Composites for Improved CA Road Surfaces. Mineta Transportation Institute, July 2021. http://dx.doi.org/10.31979/mti.2021.2046.

Full text
Abstract:
The continued use of structural plastics in consumer products, industry, and transportation represents a potential source for durable, long lasting, and recyclable roadways. Costs to dispose of reinforced plastics can be similar to procuring new asphalt with mechanical performance exceeding that of the traditional road surface. This project examines improved material development times by leveraging advanced computational material models based on validated experimental data. By testing traditional asphalt and select carbon and glass reinforced composites, both new and recycled, it is possible to develop a finite element simulation that can predict the material characteristics under a number of loads virtually, and with less lead time compared to experimental testing. From the tested specimens, composites show minimal strength degradation when recycled and used within the asphalt design envelopes considered, with an average of 49% less wear, two orders of magnitude higher compressive strength, and three orders for tensile strength. Predictive computational analysis using the validated material models developed for this investigation confirms the long-term durability.
APA, Harvard, Vancouver, ISO, and other styles
5

Friedman, Haya, Chris Watkins, Susan Lurie, and Susheng Gan. Dark-induced Reactive Oxygen Species Accumulation and Inhibition by Gibberellins: Towards Inhibition of Postharvest Senescence. United States Department of Agriculture, December 2009. http://dx.doi.org/10.32747/2009.7613883.bard.

Full text
Abstract:
Dark-induced senescence could pose a major problem in export of various crops including cuttings. The assumption of this work was that ROS which is increased at a specific organelle can serve as a signal for activation of cell senescence program. Hormones which reduce senescence in several crops like gibberellic acid (GA) and possibly cytokinin (CK) may reduce senescence by inhibiting this signal. In this study we worked on Pelargonium cuttings as well as Arabidopsis rosette. In Pelargonium the increase in ROS occurred concomitantly with increase in two SAGs, and the increase persisted in isolated chloroplasts. In Arabidopsis we used two recentlydeveloped technologies to examine these hypotheses; one is a transcriptome approach which, on one hand, enabled to monitor expression of genes within the antioxidants network, and on the other hand, determine organelle-specific ROS-related transcriptome footprint. This last approach was further developed to an assay (so called ROSmeter) for determination of the ROS-footprint resulting from defined ROS stresses. The second approach involved the monitoring of changes in the redox poise in different organelles by measuring fluorescence ratio of redox-sensitive GFP (roGFP) directed to plastids, mitochondria, peroxisome and cytoplasm. By using the roGFP we determined that the mitochondria environment is oxidized as early as the first day under darkness, and this is followed by oxidation of the peroxisome on the second day and the cytoplast on the third day. The plastids became less oxidized at the first day of darkness and this was followed by a gradual increase in oxidation. The results with the ROS-related transcriptome footprint showed early changes in ROS-related transcriptome footprint emanating from mitochondria and peroxisomes. Taken together these results suggest that the first ROS-related change occurred in mitochondria and peroxisomes. The analysis of antioxidative gene’s network did not yield any clear results about the changes occurring in antioxidative status during extended darkness. Nevertheless, there is a reduction in expression of many of the plastids antioxidative related genes. This may explain a later increase in the oxidation poise of the plastids, occurring concomitantly with increase in cell death. Gibberellic acid (GA) prevented senescence in Pelargonium leaves; however, in Arabidopsis it did not prevent chlorophyll degradation, but prevented upregulation of SAGs (Apendix Fig. 1). Gibberellic acid prevented in Pelargonium the increase in ROS in chloroplast, and we suggested that this prevents the destruction of the chloroplasts and hence, the tissue remains green. In Arabidopsis, reduction in endogenous GA and BA are probably not causing dark-induced senescence, nevertheless, these materials have some effect at preventing senescence. Neither GA nor CK had any effect on transcriptome footprint related to ROS in the various organelles, however while GA reduced expression of few general ROS-related genes, BA mainly prevented the decrease in chloroplasts genes. Taken together, GA and BA act by different pathways to inhibit senescence and GA might act via ROS reduction. Therefore, application of both hormones may act synergistically to prevent darkinduced senescence of various crops.
APA, Harvard, Vancouver, ISO, and other styles
6

Wackett, Lawrence, Raphi Mandelbaum, and Michael Sadowsky. Bacterial Mineralization of Atrazine as a Model for Herbicide Biodegradation: Molecular and Applied Aspects. United States Department of Agriculture, January 1999. http://dx.doi.org/10.32747/1999.7695835.bard.

Full text
Abstract:
Atrazine is a broadly used herbicide in agriculture and it was used here as a model to study the biodegradation of herbicides. The bacterium Pseudomonas sp. ADP metabolizes atrazine to carbon dioxide and ammonia and chloride. The genes encoding atrazine catabolism to cyanuric acid were cloned and expressed in Escherichia coli. The genes were designated atzA, atzB and atzC. Each gene was sequenced. The enzyme activities were characterized. AtzA is atrazine chlorohydrolase which takes atrazine to hydroxyatrizine. AtzB is hydroxyatrazine N-ethylaminohydrolase which produces N-isopropylammelide and N-ethylamine. AtzC is N-isopropylammelide N-isopropylaminohydrolase which produces cyanuric acid and N-isopropylamine. Each product was isolated and characterized to confirm their identity by chromatography and mass spectrometry. Sequence analysis indicated that each of the hydrolytic enzymes AtzA, AtzB and AtzC share identity which the aminohydrolase protein superfamily. Atrazine chlorohydrolase was purified to homogeneity. It was shown to have a kcat of 11 s-1 and a KM of 150 uM. It was shown to require a metal ion, either Fe(II), Mn(II) or Co(II), for activity. The atzA, atzB and atzC genes were shown to reside on a broad-host range plasmid in Pseudomonas sp. ADP. Six other recently isolated atrazine-degrading bacteria obtained from Europe and the United States contained homologs to the atz genes identified in Pseudomonas sp. ADP. The identity of the sequences were very high, being greater than 98% in all pairwise comparisons. This indicates that many atrazine-degrading bacteria worldwide metabolize atrazine via a pathway that proceeds through hydroxyatrazine, a metabolite which is non-phytotoxic and non-toxic to mammals. Enzymes were immobilized and used for degradation of atrazine in aqueous phases. The in-depth understanding of the genomics and biochemistry of the atrazine mineralization pathway enabled us to study factors affecting the prevalence of atrazine degradation in various agricultural soils under conservative and new agricultural practices. Moreover, Pseudomonas sp. ADP and/or its enzymes were added to atrazine-contaminated soils, aquifers and industrial wastewater to increase the rate and extent of atrazine biodegradation above that of untreated environments. Our studies enhance the ability to control the fate of regularly introduced pesticides in agriculture, or to reduce the environmental impact of unintentional releases.
APA, Harvard, Vancouver, ISO, and other styles
7

Schuster, Gadi, and David Stern. Integration of phosphorus and chloroplast mRNA metabolism through regulated ribonucleases. United States Department of Agriculture, August 2008. http://dx.doi.org/10.32747/2008.7695859.bard.

Full text
Abstract:
New potential for engineering chloroplasts to express novel traits has stimulated research into relevant techniques and genetic processes, including plastid transformation and gene regulation. This proposal continued our long time BARD-funded collaboration research into mechanisms that influence chloroplast RNA accumulation, and thus gene expression. Previous work on cpRNA catabolism has elucidated a pathway initiated by endonucleolytic cleavage, followed by polyadenylation and exonucleolytic degradation. A major player in this process is the nucleus-encoded exoribonuclease/polymerasepolynucleotidephoshorylase (PNPase). Biochemical characterization of PNPase has revealed a modular structure that controls its RNA synthesis and degradation activities, which in turn are responsive to the phosphate (P) concentration. However, the in vivo roles and regulation of these opposing activities are poorly understood. The objectives of this project were to define how PNPase is controlled by P and nucleotides, using in vitro assays; To make use of both null and site-directed mutations in the PNPgene to study why PNPase appears to be required for photosynthesis; and to analyze plants defective in P sensing for effects on chloroplast gene expression, to address one aspect of how adaptation is integrated throughout the organism. Our new data show that P deprivation reduces cpRNA decay rates in vivo in a PNPasedependent manner, suggesting that PNPase is part of an organismal P limitation response chain that includes the chloroplast. As an essential component of macromolecules, P availability often limits plant growth, and particularly impacts photosynthesis. Although plants have evolved sophisticated scavenging mechanisms these have yet to be exploited, hence P is the most important fertilizer input for crop plants. cpRNA metabolism was found to be regulated by P concentrations through a global sensing pathway in which PNPase is a central player. In addition several additional discoveries were revealed during the course of this research program. The human mitochondria PNPase was explored and a possible role in maintaining mitochondria homeostasis was outlined. As polyadenylation was found to be a common mechanism that is present in almost all organisms, the few examples of organisms that metabolize RNA with no polyadenylation were analyzed and described. Our experiment shaded new insights into how nutrient stress signals affect yield by influencing photosynthesis and other chloroplast processes, suggesting strategies for improving agriculturally-important plants or plants with novel introduced traits. Our studies illuminated the poorly understood linkage of chloroplast gene expression to environmental influences other than light quality and quantity. Finely, our finding significantly advanced the knowledge about polyadenylation of RNA, the evolution of this process and its function in different organisms including bacteria, archaea, chloroplasts, mitochondria and the eukaryotic cell. These new insights into chloroplast gene regulation will ultimately support plant improvement for agriculture
APA, Harvard, Vancouver, ISO, and other styles
8

Ohad, Itzhak, and Himadri Pakrasi. Role of Cytochrome B559 in Photoinhibition. United States Department of Agriculture, December 1995. http://dx.doi.org/10.32747/1995.7613031.bard.

Full text
Abstract:
The aim of this research project was to obtain information on the role of the cytochrome b559 in the function of Photosystem-II (PSII) with special emphasis on the light induced photo inactivation of PSII and turnover of the photochemical reaction center II protein subunit RCII-D1. The major goals of this project were: 1) Isolation and sequencing of the Chlamydomonas chloroplast psbE and psbF genes encoding the cytochrome b559 a and b subunits respectively; 2) Generation of site directed mutants and testing the effect of such mutation on the function of PSII under various light conditions; 3) To obtain further information on the mechanism of the light induced degradation and replacement of the PSII core proteins. This information shall serve as a basis for the understanding of the role of the cytochrome b559 in the process of photoinhibition and recovery of photosynthetic activity as well as during low light induced turnover of the D1 protein. Unlike in other organisms in which the psbE and psbF genes encoding the a and b subunits of cytochrome b559, are part of an operon which also includes the psbL and psbJ genes, in Chlamydomonas these genes are transcribed from different regions of the chloroplast chromosome. The charge distribution of the derived amino-acid sequences of psbE and psbF gene products differs from that of the corresponding genes in other organisms as far as the rule of "positive charge in" is concerned relative to the process of the polypeptide insertion in the thylakoid membrane. However, the sum of the charges of both subunits corresponds to the above rule possibly indicating co-insertion of both subunits in the process of cytochrome b559 assembly. A plasmid designed for the introduction of site-specific mutations into the psbF gene of C. reinhardtii. was constructed. The vector consists of a DNA fragment from the chromosome of C. reinhardtii which spans the region of the psbF gene, upstream of which the spectinomycin-resistance-conferring aadA cassette was inserted. This vector was successfully used to transform wild type C. reinhardtii cells. The spectinomycin resistant strain thus obtained can grow autotrophically and does not show significant changes as compared to the wild-type strain in PSII activity. The following mutations have been introduced in the psbF gene: H23M; H23Y; W19L and W19. The replacement of H23 involved in the heme binding to M and Y was meant to permit heme binding but eventually alter some or all of the electron transport properties of the mutated cytochrome. Tryptophane W19, a strictly conserved residue, is proximal to the heme and may interact with the tetrapyrole ring. Therefore its replacement may effect the heme properties. A change to tyrosine may have a lesser affect on the potential or electron transfer rate while a replacement of W19 by leucine is meant to introduce a more prominent disturbance in these parameters. Two of the mutants, FW19L and FH23M have segregated already and are homoplasmic. The rest are still grown under selection conditions until complete segregation will be obtained. All mutants contain assembled and functional PSII exhibiting an increased sensitivity of PSII to the light. Work is still in progress for the detailed characterization of the mutants PSII properties. A tobacco mutant, S6, obtained by Maliga and coworkers harboring the F26S mutation in the b subunit was made available to us and was characterized. Measurements of PSII charge separation and recombination, polypeptide content and electron flow indicates that this mutation indeed results in light sensitivity. Presently further work is in progress in the detailed characterization of the properties of all the above mutants. Information was obtained demonstrating that photoinactivation of PSII in vivo initiates a series of progressive changes in the properties of RCII which result in an irreversible modification of the RCII-D1 protein leading to its degradation and replacement. The cleavage process of the modified RCII-D1 protein is regulated by the occupancy of the QB site of RCII by plastoquinone. Newly synthesized D1 protein is not accumulated in a stable form unless integrated in reassembled RCII. Thus the degradation of the irreversibly modified RCII-D1 protein is essential for the recovery process. The light induced degradation of the RCII-D1 protein is rapid in mutants lacking the pD1 processing protease such as in the LF-1 mutant of the unicellular alga Scenedesmus obliquus. In this case the Mn binding site of PSII is abolished, the water oxidation process is inhibited and harmful cation radicals are formed following light induced electron flow in PSII. In such mutants photo-inactivation of PSII is rapid, it is not protected by ligands binding at the QB site and the degradation of the inactivated RCII-D1 occurs rapidly also in the dark. Furthermore the degraded D1 protein can be replaced in the dark in absence of light driven redox controlled reactions. The replacement of the RCII-D1 protein involves the de novo synthesis of the precursor protein, pD1, and its processing at the C-terminus end by an unknown processing protease. In the frame of this work, a gene previously isolated and sequenced by Dr. Pakrasi's group has been identified as encoding the RCII-pD1 C-terminus processing protease in the cyanobacterium Synechocystis sp. PCC 6803. The deduced sequence of the ctpA protein shows significant similarity to the bovine, human and insect interphotoreceptor retinoid-binding proteins. Results obtained using C. reinhardtii cells exposes to low light or series of single turnover light flashes have been also obtained indicating that the process of RCII-D1 protein turnover under non-photoinactivating conditions (low light) may be related to charge recombination in RCII due to back electron flow from the semiquinone QB- to the oxidised S2,3 states of the Mn cluster involved in the water oxidation process.
APA, Harvard, Vancouver, ISO, and other styles
9

Manulis, Shulamit, Christine D. Smart, Isaac Barash, Guido Sessa, and Harvey C. Hoch. Molecular Interactions of Clavibacter michiganensis subsp. michiganensis with Tomato. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697113.bard.

Full text
Abstract:
Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato plants are largely unknown. The goal of the project was to elucidate the molecular interactions between Cmmand tomato. The first objective was to analyze gene expression profiles of susceptible tomato plants infected with pathogenic and endophytic Cmmstrains. Microarray analysis identified 122 genes that were differentially expressed during early stages of infection. Cmm activated typical basal defense responses in the host including induction of defense-related genes, production of scavenging of free oxygen radicals, enhanced protein turnover and hormone synthesis. Proteomic investigation of the Cmm-tomato interaction was performed with Multi-Dimensional Protein Identification Technology (MudPIT) and mass spectroscopy. A wide range of enzymes secreted by Cmm382, including cell-wall degrading enzymes and a large group of serine proteases from different families were identified in the xylem sap of infected tomato. Based on proteomic results, the expression pattern of selected bacterial virulence genes and plant defense genes were examined by qRT-PCR. Expression of the plasmid-borne cellulase (celA), serine protease (pat-1) and serine proteases residing on the chp/tomA pathogenicity island (chpCandppaA), were significantly induced within 96 hr after inoculation. Transcription of chromosomal genes involved in cell wall degradation (i.e., pelA1, celB, xysA and xysB) was also induced in early infection stages. The second objective was to identify by VIGS technology host genes affecting Cmm multiplication and appearance of disease symptoms in plant. VIGS screening showed that out of 160 tomato genes, which could be involved in defense-related signaling, suppression of 14 genes led to increase host susceptibility. Noteworthy are the genes Snakin-2 (inhibitor of Cmm growth) and extensin-like protein (ELP) involved in cell wall fortification. To further test the significance of Snakin -2 and ELP in resistance towards Cmm, transgenic tomato plants over-expressing the two genes were generated. These plants showed partial resistance to Cmm resulting in a significant delay of the wilt symptoms and reduction in size of canker lesion compared to control. Furthermore, colonization of the transgenic plants was significantly lower. The third objective was to assess the involvement of ethylene (ET), jasmonate (JA) and salicylic acid (SA) in Cmm infection. Microarray and proteomic studies showed the induction of enzymes involved in ET and JA biosynthesis. Cmm promoted ET production 8 days after inoculation and SIACO, a key enzyme of ET biosynthesis, was upregulated. Inoculation of the tomato mutants Never ripe (Nr) impaired in ET perception and transgenic plants with reduced ET synthesis significantly delayed wilt symptoms as compared to the wild-type plants. The retarded wilting in Nr plants was shown to be a specific effect of ET insensitivity and was not due to altered expression of defense related genes, reduced bacterial population or decrease in ethylene biosynthesis . In contrast, infection of various tomato mutants impaired in JA biosynthesis (e.g., def1, acx1) and JA insensitive mutant (jai1) yielded unequivocal results. The fourth objective was to determine the role of cell wall degrading enzymes produced by Cmm in xylem colonization and symptoms development. A significance increase (2 to 7 fold) in expression of cellulases (CelA, CelB), pectate lyases (PelA1, PelA2), polygalacturonase and xylanases (XylA, XylB) was detected by qRT-PCR and by proteomic analysis of the xylem sap. However, with the exception of CelA, whose inactivation led to reduced wilt symptoms, inactivation of any of the other cell wall degrading enzymes did not lead to reduced virulence. Results achieved emphasized the complexity involved in Cmm-tomato interactions. Nevertheless they provide the basis for additional research which will unravel the mechanism of Cmm pathogenicity and formulating disease control measures.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Plastic degradation' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography