scholarly journals Bacterial Abundance, Diversity and Activity During Long-Term Colonization of Non-biodegradable and Biodegradable Plastics in Seawater

2021 ◽  
Vol 12 ◽  
Author(s):  
Charlene Odobel ◽  
Claire Dussud ◽  
Lena Philip ◽  
Gabrielle Derippe ◽  
Marion Lauters ◽  
...  
Keyword(s):  
Biodegradable Plastics ◽  
Epifluorescence Microscopy ◽  
Leucine Incorporation ◽  
Natural Seawater ◽  
Experimental Conditions ◽  
Continuous Increase ◽  
Continuous Growth ◽  
Plastic Type ◽  
Biofilm Development

The microorganisms living on plastics called “plastisphere” have been classically described as very abundant, highly diverse, and very specific when compared to the surrounding environments, but their potential ability to biodegrade various plastic types in natural conditions have been poorly investigated. Here, we follow the successive phases of biofilm development and maturation after long-term immersion in seawater (7 months) on conventional [fossil-based polyethylene (PE) and polystyrene (PS)] and biodegradable plastics [biobased polylactic acid (PLA) and polyhydroxybutyrate-co-hydroxyvalerate (PHBV), or fossil-based polycaprolactone (PCL)], as well as on artificially aged or non-aged PE without or with prooxidant additives [oxobiodegradable (OXO)]. First, we confirmed that the classical primo-colonization and growth phases of the biofilms that occurred during the first 10 days of immersion in seawater were more or less independent of the plastic type. After only 1 month, we found congruent signs of biodegradation for some bio-based and also fossil-based materials. A continuous growth of the biofilm during the 7 months of observation (measured by epifluorescence microscopy and flow cytometry) was found on PHBV, PCL, and artificially aged OXO, together with a continuous increase in intracellular (3H-leucine incorporation) and extracellular activities (lipase, aminopeptidase, and β-glucosidase) as well as subsequent changes in biofilm diversity that became specific to each polymer type (16S rRNA metabarcoding). No sign of biodegradation was visible for PE, PS, and PLA under our experimental conditions. We also provide a list of operational taxonomic units (OTUs) potentially involved in the biodegradation of these polymers under natural seawater conditions, such as Pseudohongiella sp. and Marinobacter sp. on PCL, Marinicella litoralis and Celeribacter sp. on PHBV, or Myxococcales on artificially aged OXO. This study opens new routes for a deeper understanding of the polymers’ biodegradability in seawaters, especially when considering an alternative to conventional fossil-based plastics.

scholarly journals Wood creep data collection and unbiased parameter identification of compliance functions

Holzforschung ◽  
2020 ◽  
Vol 74 (11) ◽  
pp. 1011-1020
Author(s):  
Danyang Tong ◽  
Susan Alexis Brown ◽  
David Corr ◽  
Gianluca Cusatis
Keyword(s):  
Parameter Identification ◽  
Prediction Models ◽  
Tall Buildings ◽  
Building Design ◽  
Parameter Distribution ◽  
Experimental Conditions ◽  
Global Emission ◽  
Wood Construction ◽  
Parameter Values

AbstractRising global emission have led to a renewed popularity of timber in building design, including timber-concrete tall buildings up to 18 stories. In spite of this surge in wood construction, there remains a gap in understanding of long-term structural behavior, particularly wood creep. Unlike concrete, code prescriptions for wood design are lacking in robust estimates for structural shortening. Models for wood creep have become increasingly necessary due to the potential for unforeseen shortening, especially with respect to differential shortening. These effects can have serious impacts as timber building heights continue to grow. This study lays the groundwork for wood compliance prediction models for use in timber design. A thorough review of wood creep studies was conducted and viable experimental results were compiled into a database. Studies were chosen based on correlation of experimental conditions with a realistic building environment. An unbiased parameter identification method, originally applied to concrete prediction models, was used to fit multiple compliance functions to each data curve. Based on individual curve fittings, statistical analysis was performed to determine the best fit function and average parameter values for the collective database. A power law trend in wood creep, with lognormal parameter distribution, was confirmed by the results.

scholarly journals Edaphic factors and plants influence denitrification in soils from a long-term arable experiment

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ian M. Clark ◽  
Qingling Fu ◽  
Maïder Abadie ◽  
Elizabeth R. Dixon ◽  
Aimeric Blaud ◽  
...  
Keyword(s):  
Gas Production ◽  
Soil Treatment ◽  
Soil Microbiome ◽  
Arable Soils ◽  
Experimental Conditions ◽  
Mineral N ◽  
Nitrate Availability ◽  
Denitrification Gene ◽  
Denitrification Genes

Abstract Factors influencing production of greenhouse gases nitrous oxide (N2O) and nitrogen (N2) in arable soils include high nitrate, moisture and plants; we investigate how differences in the soil microbiome due to antecedent soil treatment additionally influence denitrification. Microbial communities, denitrification gene abundance and gas production in soils from tilled arable plots with contrasting fertilizer inputs (no N, mineral N, FYM) and regenerated woodland in the long-term Broadbalk field experiment were investigated. Soil was transferred to pots, kept bare or planted with wheat and after 6 weeks, transferred to sealed chambers with or without K15NO3 fertilizer for 4 days; N2O and N2 were measured daily. Concentrations of N2O were higher when fertilizer was added, lower in the presence of plants, whilst N2 increased over time and with plants. Prior soil treatment but not exposure to N-fertiliser or plants during the experiment influenced denitrification gene (nirK, nirS, nosZI, nosZII) relative abundance. Under our experimental conditions, denitrification generated mostly N2; N2O was around 2% of total gaseous N2 + N2O. Prior long-term soil management influenced the soil microbiome and abundance of denitrification genes. The production of N2O was driven by nitrate availability and N2 generation increased in the presence of plants.

Crevice Corrosion Studies on Corrosion Resistant Alloys in Stagnant Natural Seawater

2012 ◽  
Vol 610-613 ◽  
pp. 276-279
Author(s):  
Laura L. Machuca ◽  
Stuart I. Bailey ◽  
Rolf Gubner
Keyword(s):  
Crevice Corrosion ◽  
Corrosion Potential ◽  
Natural Seawater ◽  
Corrosion Resistant ◽  
Testing Procedures ◽  
Corrosion Studies ◽  
Long Term Performance ◽  
Term Performance ◽  
Positive Effect

Crevice corrosion (CC) was investigated for a number of selected corrosion resistant alloys in natural seawater containing microorganisms for up to 18 months under stagnant conditions. Experimental controls consisted of tests in natural seawater filtered in accordance with hydrostatic testing procedures. The corrosion potential of alloys was monitored throughout exposure and corrosion was evaluated by weight loss and 3D optical microscopy. CC was initiated on several alloys and corrosion rates in time indicated a positive effect of seawater filtration on the long-term performance of the alloys. Microbial adhesion, as indicated by fluorescence microscopy, occurred mainly outside the crevice and differed according to the nature of the substratum surface.

Verbalization and musical memory in string players

2017 ◽  
Vol 23 (2) ◽  
pp. 212-230
Author(s):  
Eric Timperman ◽  
Peter Miksza
Keyword(s):  
Recall Performance ◽  
Experimental Conditions ◽  
Immediate Recall ◽  
Short And Long Term ◽  
The Creation ◽  
24 Hour Recall ◽  
Associative Recall ◽  
Verbal Analysis ◽  
Musical Memory

The purpose of this study was to examine the effect of verbalization about a brief etude on collegiate string players’ short- and long-term recall of the etude in question. We examined competing hypotheses that suggest it is possible that verbalization (i.e., verbal analysis of musical features) (a) could aid in recall both by highlighting patterns and constraints that inform the music’s creation and by facilitating the creation of explicit performance cues that help to bridge gaps between associative recall chains or (b) may hinder recall by interfering with the creation of procedural and auditory memories necessary for musical performance. Participants ( N = 20) were assigned to experimental conditions in which they learned an unfamiliar etude either through repetition alone or through repetition followed by the completion of a verbalization worksheet provided by the experimenter. Recall was tested both immediately following initial practice and 24 hours later to examine the effect of verbalization on both short- and long-term retention. Findings indicated no differences between groups on immediate recall performance but significant differences at the 24-hour recall task with participants in the verbalization condition recalling more material. In addition, the patterns of errors found across groups indicated a strong primacy effect. Theoretical implications for the study of memory processes in musical contexts and practical implications regarding the preparation of memorized performance are discussed.

scholarly journals Comparative biofilm assays using Enterococcus faecalis OG1RF identify new determinants of biofilm formation

2021 ◽  
Author(s):  
Julia L. E. Willett ◽  
Jennifer L. Dale ◽  
Lucy M. Kwiatkowski ◽  
Jennifer L. Powers ◽  
Michelle L. Korir ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Growth Medium ◽  
Biofilm Formation ◽  
Time Course ◽  
Opportunistic Pathogen ◽  
Genetic Determinants ◽  
Experimental Conditions ◽  
Biofilm Reactors ◽  
Biofilm Architecture ◽  
Biofilm Development

AbstractEnterococcus faecalis is a common commensal organism and a prolific nosocomial pathogen that causes biofilm-associated infections. Numerous E. faecalis OG1RF genes required for biofilm formation have been identified, but few studies have compared genetic determinants of biofilm formation and biofilm morphology across multiple conditions. Here, we cultured transposon (Tn) libraries in CDC biofilm reactors in two different media and used Tn sequencing (TnSeq) to identify core and accessory biofilm determinants, including many genes that are poorly characterized or annotated as hypothetical. Multiple secondary assays (96-well plates, submerged Aclar, and MultiRep biofilm reactors) were used to validate phenotypes of new biofilm determinants. We quantified biofilm cells and used fluorescence microscopy to visualize biofilms formed by 6 Tn mutants identified using TnSeq and found that disrupting these genes (OG1RF_10350, prsA, tig, OG1RF_10576, OG1RF_11288, and OG1RF_11456) leads to significant time- and medium-dependent changes in biofilm architecture. Structural predictions revealed potential roles in cell wall homeostasis for OG1RF_10350 and OG1RF_11288 and signaling for OG1RF_11456. Additionally, we identified growth medium-specific hallmarks of OG1RF biofilm morphology. This study demonstrates how E. faecalis biofilm architecture is modulated by growth medium and experimental conditions, and identifies multiple new genetic determinants of biofilm formation.ImportanceE. faecalis is an opportunistic pathogen and a leading cause of hospital-acquired infections, in part due to its ability to form biofilms. A complete understanding of the genes required for E. faecalis biofilm formation as well as specific features of biofilm morphology related to nutrient availability and growth conditions is crucial for understanding how E. faecalis biofilm-associated infections develop and resist treatment in patients. We employed a comprehensive approach to analysis of biofilm determinants by combining TnSeq primary screens with secondary phenotypic validation using diverse biofilm assays. This enabled identification of numerous core (important under many conditions) and accessory (important under specific conditions) biofilm determinants in E. faecalis OG1RF. We found multiple genes whose disruption results in drastic changes to OG1RF biofilm morphology. These results expand our understanding of the genetic requirements for biofilm formation in E. faecalis that affect the time course of biofilm development as well as the response to specific nutritional conditions.

scholarly journals A low-cost automized anaerobic chamber for long-term growth experiments and sample handling

2020 ◽  
Author(s):  
Achim J. Herrmann ◽  
Michelle M. Gehringer
Keyword(s):  
Environmental Control ◽  
Low Cost ◽  
Environmental Data ◽  
Atmospheric Environment ◽  
Regular Growth ◽  
Continuous Growth ◽  
Sample Handling ◽  
Hand Column ◽  
Oxygen Sensitive

1AbstractThe handling of oxygen sensitive samples and growth of obligate anaerobic organisms requires the stringent exclusion of oxygen, which is omnipresent in our normal atmospheric environment. Anaerobic workstations (aka. Glove boxes) enable the handling of oxygen sensitive samples during complex procedures, or the long-term incubation of anaerobic organisms. Depending on the application requirements, commercial workstations can cost up to 60.000 €. Here we present the complete build instructions for a highly adaptive, Arduino based, anaerobic workstation for microbial cultivation and sample handling, with features normally found only in high cost commercial solutions. This build can automatically regulate humidity, H2 levels (as oxygen reductant), log the environmental data and purge the airlock. It is built as compact as possible to allow it to fit into regular growth chambers for full environmental control. In our experiments, oxygen levels during the continuous growth of oxygen producing cyanobacteria, stayed under 0.03 % for 21 days without needing user intervention. The modular Arduino controller allows for the easy incorporation of additional regulation parameters, such as CO2 concentration or air pressure. This paper provides researchers with a low cost, entry level workstation for anaerobic sample handling with the flexibility to match their specific experimental needs.Specifications table[please fill in right-hand column of the table below]

scholarly journals Study on the production and use of biomass energy in the Timis County

2021 ◽  
Vol 26 (2) ◽  
pp. 2434-2440
Author(s):  
CRISTINA BACĂU ◽  
◽  
NICOLETA MATEOC-SÎRB ◽  
RAMONA CIOLAC ◽  
TEODOR MATEOC ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Energy Production ◽  
Nuclear Energy ◽  
Renewable Energy Sources ◽  
Biomass Energy ◽  
Renewable Energy Resources ◽  
Continuous Increase ◽  
Fossil Energy ◽  
Term Energy

The use of renewable energy resources is gaining more and more ground, thanks to the continuous increase in the price of fossil energy and the decrease in stocks, and the management of waste from nuclear energy production, respectively. The implementation of an energy strategy to harness the potential of renewable energy sources (RES) is part of the coordinates of Romania’s medium – and long-term energy development and provides the appropriate framework for the making of decisions on energy alternatives and the inclusion in the Community acquis in the field. In this respect, a study on the biomass potential of Timiş County and on the possibilities of producing unconventional energy from biomass has been carried out. The study is based on research, data collection from the literature, as well as from official documents or official websites, the processing and interpretation of the data and their quantitative and qualitative analysis. It was concluded that biomass is a promising renewable energy source for Romania, both in terms of potential and in terms of usability.

Safety and Performance Evaluation of Su2ura Approximation, a New Suturing Device, in Pigs

2021 ◽  
pp. 019262332110679
Author(s):  
Yuval Ramot ◽  
Serge Rousselle ◽  
Michal Steiner ◽  
Yossi Lavie ◽  
Nati Ezov ◽  
...  
Keyword(s):  
Minimal Invasive Surgery ◽  
Minimal Invasive ◽  
Experimental Conditions ◽  
Single Action ◽  
Treatment Groups ◽  
Novel Device ◽  
Fibrotic Scar ◽  
And Performance ◽  
Tissue Approximation

One of the challenging aspects of minimal invasive surgery (MIS) is intracorporal suturing, which can be significantly time-consuming. Therefore, there is a rising need for devices that can facilitate the suturing procedure in MIS. Su2ura Approximation Device (Su2ura Approximation) is a novel device developed to utilize the insertion of anchors threaded with stitches to allow a single action placement of a suture. The objective of this study was to evaluate the long-term safety and tissue approximation of Su2ura Approximation in comparison to Endo Stitch + Surgidac sutures in female domestic pigs. All incision sites were successfully closed by both methods. Firm consolidation within and around the incision site was noted in several animals in both treatment groups, which corresponded histopathologically to islands of ectopic cartilage or bone spicules within the fibrotic scar. These changes reflect heterotopic ossification that is commonly seen in the healing of abdominal operation sites in pigs. No other abnormal findings were observed throughout the study period. In conclusion, the use of Su2ura Approximation under the present experimental conditions revealed no safety concerns.

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