scholarly journals Microbial degradation of plastic in aqueous solutions demonstrated by CO2 evolution and quantification

2019 ◽  
Author(s):  
Ruth-Sarah Rose ◽  
Katherine H. Richardson ◽  
Elmeri Johannes Latvanen ◽  
China A. Hanson ◽  
Marina Resmini ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Critical Factor ◽  
Model Organisms ◽  
Bacterial Respiration ◽  
Rhodococcus Rhodochrous ◽  
Testing Methods ◽  
Polymer Molecular Weight ◽  
New Approach ◽  
Marine Systems ◽  
Single Carbon Source

AbstractThe environmental accumulation of plastics worldwide is a consequence of the durability of the material. Alternative polymers, marketed as biodegradable, present a potential solution to mitigate their ecological damage. However, understanding of biodegradability has been hindered by a lack of reproducible testing methods. Here, we present a new approach to assess biodegradability by monitoring bacterial respiration, in an aqueous media supplemented with a polymer as a single carbon source. Rhodococcus rhodochrous and Alcanivorax borkumensis are good model organisms for soil and marine systems respectively, allowing simulations of plastic biodegradation in these key environments. We demonstrate that polymer molecular weight reduction is the critical factor in the biodegradability of low-density polyethylene. Additionally, we tested a wide variety of plastics, including environmentally weathered and laboratory aged samples, using the same method allowing direct comparisons of the relative biodegradability of various polymers.

scholarly journals Microbial Degradation of Plastic in Aqueous Solutions Demonstrated by CO2 Evolution and Quantification

2020 ◽  
Vol 21 (4) ◽  
pp. 1176 ◽  
Author(s):  
Ruth-Sarah Rose ◽  
Katherine H. Richardson ◽  
Elmeri Johannes Latvanen ◽  
China A. Hanson ◽  
Marina Resmini ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Low Density Polyethylene ◽  
Model Organisms ◽  
Bacterial Respiration ◽  
Clear Correlation ◽  
Co2 Evolution ◽  
Rhodococcus Rhodochrous ◽  
Testing Methods ◽  
Marine Systems ◽  
Novel Method

The environmental accumulation of plastics worldwide is a consequence of the durability of the material. Alternative polymers, marketed as biodegradable, present a potential solution to mitigate their ecological damage. However, understanding of biodegradability has been hindered by a lack of reproducible testing methods. We developed a novel method to evaluate the biodegradability of plastic samples based on the monitoring of bacterial respiration in aqueous media via the quantification of CO2 produced, where the only carbon source available is from the polymer. Rhodococcus rhodochrous and Alcanivorax borkumensis were used as model organisms for soil and marine systems, respectively. Our results demonstrate that this approach is reproducible and can be used with a variety of plastics, allowing comparison of the relative biodegradability of the different materials. In the case of low-density polyethylene, the study demonstrated a clear correlation between the molecular weight of the sample and CO2 released, taken as a measure of biodegradability.

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

Novel Methods for High-Cycle Fatigue Life Determination

2019 ◽  
Vol 810 ◽  
pp. 40-45
Author(s):  
Pavel Konopík ◽  
Radek Procházka ◽  
Martin Rund ◽  
Jan Džugan
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Testing Methods ◽  
Destructive Testing ◽  
New Approach ◽  
Constant Loading ◽  
Thermographic Analysis ◽  
Novel Methods

In the present paper, two novel methods for determining the fatigue limit are presented. Despite the fact that these methods are different in principle, both represent a new approach to testing where the main benefit is reduced consumption of material. The first method is based on small round specimens and can be considered as one of semi-destructive testing methods. The second method is based on infrared thermographic analysis and requires only one specimen. Results obtained with these techniques were compared with those obtained from standard high-cycle force-controlled fatigue tests under constant loading until failure.

scholarly journals Toxicity testing is evolving!

2020 ◽  
Vol 9 (2) ◽  
pp. 67-80 ◽  
Author(s):  
Ida Fischer ◽  
Catherine Milton ◽  
Heather Wallace
Keyword(s):  
Systematic Approach ◽  
Toxicity Testing ◽  
Testing Methods ◽  
Regulatory Requirements ◽  
New Approach ◽  
Chemical Substances ◽  
Experimental Animals ◽  
The Public ◽  
Efficient Management ◽  
Regulatory Decisions

Abstract The efficient management of the continuously increasing number of chemical substances used in today’s society is assuming greater importance than ever before. Toxicity testing plays a key role in the regulatory decisions of agencies and governments that aim to protect the public and the environment from the potentially harmful or adverse effects of these multitudinous chemicals. Therefore, there is a critical need for reliable toxicity-testing methods to identify, assess and interpret the hazardous properties of any substance. Traditionally, toxicity-testing approaches have been based on studies in experimental animals. However, in the last 20 years, there has been increasing concern regarding the sustainability of these methodologies. This has created a real need for the development of new approach methodologies (NAMs) that satisfy the regulatory requirements and are acceptable and affordable to society. Numerous initiatives have been launched worldwide in attempts to address this critical need. However, although the science to support this is now available, the legislation and the pace of NAMs acceptance is lagging behind. This review will consider some of the various initiatives in Europe to identify NAMs to replace or refine the current toxicity-testing methods for pharmaceuticals. This paper also presents a novel systematic approach to support the desired toxicity-testing methodologies that the 21st century deserves.

scholarly journals Dynamic subcellular localization of a respiratory complex controls bacterial respiration

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
François Alberge ◽  
Leon Espinosa ◽  
Farida Seduk ◽  
Léa Sylvi ◽  
René Toci ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Subcellular Localization ◽  
Critical Factor ◽  
Bacterial Respiration ◽  
Metabolic Demand ◽  
Respiratory Complex ◽  
Spatiotemporal Regulation ◽  
Metabolic Conditions ◽  
Respiratory Chains ◽  
Regulatory Flexibility

Respiration, an essential process for most organisms, has to optimally respond to changes in the metabolic demand or the environmental conditions. The branched character of their respiratory chains allows bacteria to do so by providing a great metabolic and regulatory flexibility. Here, we show that the native localization of the nitrate reductase, a major respiratory complex under anaerobiosis in Escherichia coli, is submitted to tight spatiotemporal regulation in response to metabolic conditions via a mechanism using the transmembrane proton gradient as a cue for polar localization. These dynamics are critical for controlling the activity of nitrate reductase, as the formation of polar assemblies potentiates the electron flux through the complex. Thus, dynamic subcellular localization emerges as a critical factor in the control of respiration in bacteria.

scholarly journals Complex Risk Statistics with Scenario Analysis

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Fei Sun ◽  
Yichuan Dong
Keyword(s):  
Neural Networks ◽  
Risk Management ◽  
Scenario Analysis ◽  
Special Class ◽  
Intelligent Systems ◽  
Deep Neural Networks ◽  
Critical Factor ◽  
New Approach ◽  
Dual Representations

Complex risk is a critical factor for both intelligent systems and risk management. In this paper, we consider a special class of risk statistics, named complex risk statistics. Our result provides a new approach for addressing complex risk, especially in deep neural networks. By further developing the properties related to complex risk statistics, we are able to derive dual representations for such risk.

scholarly journals Recent Developments in Using Drosophila as a Model for Human Genetic Disease

2018 ◽  
Author(s):  
Christine Oriel ◽  
Paul Lasko
Keyword(s):  
Genetic Disease ◽  
Genetic Variant ◽  
Genetic Diseases ◽  
Model Organisms ◽  
Human Genetic Disease ◽  
New Approach ◽  
Linked Gene ◽  
The Us ◽  
Recent Developments ◽  
Disease Loci

Many insights into human disease have been built on experimental results in Drosophila, and research in fruit flies is often justified on the basis of its predictive value for questions related to human health. Additionally, there is now a growing recognition of the value of Drosophila for the study of rare human genetic diseases, either as a means of validating the causative nature of a candidate genetic variant found in patients, or as a means of obtaining functional information about a novel disease-linked gene when there is little known about it. For these reasons, funders in the US, Europe, and Canada have launched targeted programs to link human geneticists working on discovering new rare disease loci with researchers who work on the counterpart genes in Drosophila and other model organisms. Several of these initiatives are described here, as are a number of output publications that validate this new approach.

scholarly journals 1H-Imidazole-2,5-Dicarboxamides as NS4A Peptidomimetics: Identification of a New Approach to Inhibit HCV-NS3 Protease

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 479
Author(s):  
Abdelsattar M. Omar ◽  
Mahmoud A. Elfaky ◽  
Stefan T. Arold ◽  
Sameh H. Soror ◽  
Maan T. Khayat ◽  
...  
Keyword(s):  
First Generation ◽  
Inhibitory Concentration ◽  
Critical Factor ◽  
Peptide Inhibitors ◽  
New Approach ◽  
New Class ◽  
Structure Activity ◽  
Aggregation Temperature ◽  
Dynamics Simulations ◽  
Ns3 Protease

The nonstructural (NS) protein NS3/4A protease is a critical factor for hepatitis C virus (HCV) maturation that requires activation by NS4A. Synthetic peptide mutants of NS4A were found to inhibit NS3 function. The bridging from peptide inhibitors to heterocyclic peptidomimetics of NS4A has not been considered in the literature and, therefore, we decided to explore this strategy for developing a new class of NS3 inhibitors. In this report, a structure-based design approach was used to convert the bound form of NS4A into 1H-imidazole-2,5-dicarboxamide derivatives as first generation peptidomimetics. This scaffold mimics the buried amino acid sequence Ile-25` to Arg-28` at the core of NS4A21`–33` needed to activate the NS3 protease. Some of the synthesized compounds (Coded MOC) were able to compete with and displace NS4A21`–33` for binding to NS3. For instance, N5-(4-guanidinobutyl)-N2-(n-hexyl)-1H-imidazole-2,5-dicarboxamide (MOC-24) inhibited the binding of NS4A21`–33` with a competition half maximal inhibitory concentration (IC50) of 1.9 ± 0.12 µM in a fluorescence anisotropy assay and stabilized the denaturation of NS3 by increasing the aggregation temperature (40% compared to NS4A21`–33`). MOC-24 also inhibited NS3 protease activity in a fluorometric assay. Molecular dynamics simulations were conducted to rationalize the differences in structure–activity relationship (SAR) between the active MOC-24 and the inactive MOC-26. Our data show that MOC compounds are possibly the first examples of NS4A peptidomimetics that have demonstrated promising activities against NS3 proteins.

scholarly journals A New Approach for Glyco-Functionalization of Collagen-Based Biomaterials

2019 ◽  
Vol 20 (7) ◽  
pp. 1747 ◽  
Author(s):  
Ines Figuereido ◽  
Alice Paiotta ◽  
Roberta Dal Magro ◽  
Francesca Tinelli ◽  
Roberta Corti ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Extracellular Matrix ◽  
Cell Fate ◽  
Cell Biology ◽  
Aqueous Media ◽  
New Approach ◽  
Cell Microenvironment ◽  
Fate Control ◽  
Ecm Proteins ◽  
Cell Fate Control

The cell microenvironment plays a pivotal role in mediating cell adhesion, survival, and proliferation in physiological and pathological states. The relevance of extracellular matrix (ECM) proteins in cell fate control is an important issue to take into consideration for both tissue engineering and cell biology studies. The glycosylation of ECM proteins remains, however, largely unexplored. In order to investigate the physio-pathological effects of differential ECM glycosylation, the design of affordable chemoselective methods for ECM components glycosylation is desirable. We will describe a new chemoselective glycosylation approach exploitable in aqueous media and on non-protected substrates, allowing rapid access to glyco-functionalized biomaterials.

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