scholarly journals Microbial Degradation of Rubber: Actinobacteria

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1989
Author(s):  
Ann Anni Basik ◽  
Jean-Jacques Sanglier ◽  
Chia Tiong Yeo ◽  
Kumar Sudesh
Keyword(s):  
Double Bond ◽  
Chemical Processes ◽  
Molecular Characteristics ◽  
Daily Lives ◽  
Structural Modifications ◽  
Synthetic Rubber ◽  
Rubber Waste ◽  
Environmentally Responsible ◽  
By Products ◽  
Responsible Manner

Rubber is an essential part of our daily lives with thousands of rubber-based products being made and used. Natural rubber undergoes chemical processes and structural modifications, while synthetic rubber, mainly synthetized from petroleum by-products are difficult to degrade safely and sustainably. The most prominent group of biological rubber degraders are Actinobacteria. Rubber degrading Actinobacteria contain rubber degrading genes or rubber oxygenase known as latex clearing protein (lcp). Rubber is a polymer consisting of isoprene, each containing one double bond. The degradation of rubber first takes place when lcp enzyme cleaves the isoprene double bond, breaking them down into the sole carbon and energy source to be utilized by the bacteria. Actinobacteria grow in diverse environments, and lcp gene containing strains have been detected from various sources including soil, water, human, animal, and plant samples. This review entails the occurrence, physiology, biochemistry, and molecular characteristics of Actinobacteria with respect to its rubber degrading ability, and discusses possible technological applications based on the activity of Actinobacteria for treating rubber waste in a more environmentally responsible manner.

scholarly journals Performance Evaluation of the SrZrxSn1-xO3 Photocatalytic System for Remazol Yellow Dye Degradation Employing Box-Behnken Design

2021 ◽  
Vol 10 (2) ◽  
pp. e48610212328
Author(s):  
Yohanna Ribeiro Klafke ◽  
Mayara Macedo da Mata ◽  
Ieda Maria Garcia dos Satos ◽  
Mary Cristina Ferreira Alves ◽  
Simone da Silva Simoes
Keyword(s):  
Dye Degradation ◽  
Large Family ◽  
Heterogeneous Photocatalysis ◽  
Textile Dyes ◽  
Chemical Processes ◽  
Box Behnken Design ◽  
Structural Modifications ◽  
Photocatalytic System ◽  
Golden Yellow ◽  
By Products

Contamination of effluents often occurs due to improper disposal of textile dyes or their by-products. These can often be carcinogenic and/or mutagenic to the biome. Given the above, the need for effective methods for treating effluents is clear. This treatment occurs by biological, physical, and/or chemical processes. Regarding chemical processes, heterogeneous photocatalysis stands out, mainly because it guarantees an effective degradation of contaminants. In this sense, mixed metal oxides, act as photocatalysts and constitute structures capable of producing a large family of solids with physical properties suitable for the degradation of many pollutants. Modified ABO3 perovskites, as in the case of the SrZrxSn1-xO3 semiconductor system, are effective in the degradation of textile dyes in effluents. The present work aimed to use the Box-Behnken model to evaluate the performance of the oxides resulting from the structural modifications of the perovskite SrZrxSn1-xO3 system, concerning the discoloration of the golden yellow dye remazol. The synthesized oxides were characterized by instrumental techniques and a Box-Behnken 34 project was developed. From this, the influence of some factors such as structural modification, oxide mass, exposure time, and the number of UVC lamps was evaluated. The discoloration of the dye was monitored from the attenuation of the absorbance at the wavelength 411 nm. According to the results obtained, the highest percentage of discoloration was obtained using the modified oxide SrZr0,25Sn0,75O3 for an approximate time of 6 hours in contact with 1 UVC lamp.

Natural and Synthetic Rubber. IV. 4-Methyl-4-Octene by Isoprene Ethylation

1930 ◽  
Vol 3 (3) ◽  
pp. 483-484
Author(s):  
Thomas Midgley ◽  
Albert L. Henne
Keyword(s):  
Double Bond ◽  
Synthetic Rubber ◽  
Double Bond System ◽  
Bond System ◽  
Usual Behavior ◽  
Natural And Synthetic ◽  
Long Chains

Abstract Isoprene has been ethylated; 4-methyl-4-octene was formed exclusively. The structure of this nonene is in agreement with the usual behavior of a conjugated double bond system. This type of addition is further evidence in favor of the hypothesis which regards the polymerization of isoprene to synthetic rubber as the formation of long chains of isoprene units linked together- by ordinary valences in the 1,4-position.

scholarly journals Allergen Immunotherapy: Current and Future Trends

Cells ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 212
Author(s):  
Gandhi F. Pavón-Romero ◽  
Maria Itzel Parra-Vargas ◽  
Fernando Ramírez-Jiménez ◽  
Esmeralda Melgoza-Ruiz ◽  
Nancy H. Serrano-Pérez ◽  
...  
Keyword(s):  
Adverse Reactions ◽  
Allergen Immunotherapy ◽  
Immunological Tolerance ◽  
Chemical Processes ◽  
Structural Modifications ◽  
Insect Venom ◽  
Cell Counts ◽  
Immunological Effects ◽  
Allergen Identification ◽  
Disease Modifying Treatment

Allergen immunotherapy (AIT) is the sole disease-modifying treatment for allergic rhinitis; it prevents rhinitis from progressing to asthma and lowers medication use. AIT against mites, insect venom, and certain kinds of pollen is effective. The mechanism of action of AIT is based on inducing immunological tolerance characterized by increased IL-10, TGF-β, and IgG4 levels and Treg cell counts. However, AIT requires prolonged schemes of administration and is sometimes associated with adverse reactions. Over the last decade, novel forms of AIT have been developed, focused on better allergen identification, structural modifications to preserve epitopes for B or T cells, post-traductional alteration through chemical processes, and the addition of adjuvants. These modified allergens induce clinical-immunological effects similar to those mentioned above, increasing the tolerance to other related allergens but with fewer side effects. Clinical studies have shown that molecular AIT is efficient in treating grass and birch allergies. This article reviews the possibility of a new AIT to improve the treatment of allergic illness.

scholarly journals Simple Environmentally-Friendly Reduction of 4-Nitrophenol

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 458 ◽  
Author(s):  
Albert Serrà ◽  
Raül Artal ◽  
Maria Pozo ◽  
Jaume Garcia-Amorós ◽  
Elvira Gómez
Keyword(s):  
Electrochemical Reduction ◽  
Hydrogen Evolution ◽  
Chemical Processes ◽  
Operating Conditions ◽  
Chemical Degradation ◽  
Applied Potential ◽  
Acidic Media ◽  
Nitrophenol Reduction ◽  
Aromatic Species ◽  
By Products

The low molecular-mass organic compound 4-nitrophenol is involved in many chemical processes and is commonly present in soils and in surface and ground waters, thereby causing severe environmental impact and health risk. Several methods have been proposed for its transformation (bio and chemical degradation). However, these strategies not only produce equally or more toxic aromatic species but also require harsh operating conditions and/or time-consuming treatments. In this context, we report a comprehensive and systematic study of the electrochemical reduction of 4-nitrophenol as a viable alternative. We have explored the electrochemical reduction of this pollutant over different metallic and carbonaceous substrata. Specifically, we have focused on the use of gold and silver working electrodes since they combine a high electrocatalytic activity for 4-nitrophenol reduction and a low electrocatalytic capacity for hydrogen evolution. The influence of the pH, temperature, and applied potential have also been considered as crucial parameters in the overall optimization of the process. While acidic media and high temperatures favor the clean reduction of 4-nitrophenol to 4-aminophenol, the simultaneous hydrogen evolution is pernicious for this purpose. Herein, a simple and effective electrochemical method for the transformation of 4-nitrophenol into 4-aminophenol is proposed with virtually no undesired by-products.

scholarly journals Science and commercialism in Antarctica

1999 ◽  
Vol 11 (2) ◽  
pp. 129-129
Author(s):  
Clive Howard-Williams
Keyword(s):  
Significant Role ◽  
Environmental Awareness ◽  
The Public ◽  
Working Through ◽  
Environmentally Responsible ◽  
The Antarctic ◽  
Visitor Numbers ◽  
Responsible Manner

There are increasing commercial pressures to send more people to the Antarctic. Visitor numbers each summer now exceed scientist numbers on the continent. The commercial operators working through IAATO have, to date, been largely acting in an environmentally responsible manner, realising that there is no point killing the goose with the golden egg. In fact, it has been argued that visitors to the Antarctic, many of whom are wealthy or influential, have played a significant role in increasing environmental awareness of the continent and its wildlife to politicians and to the public.

Silyl-substituted α,β-Unsaturated Ketones from the Reaction of Silylvinylmetallic Reagents with Acid Anhydrides

1973 ◽  
Vol 51 (12) ◽  
pp. 2024-2032 ◽  
Author(s):  
A. G. Brook ◽  
J. M. Duff
Keyword(s):  
Double Bond ◽  
Low Temperatures ◽  
Silyl Group ◽  
Unsaturated Ketones ◽  
Carbon Double Bond ◽  
Benzoic Anhydride ◽  
Acid Anhydrides ◽  
By Products

The reactions of a series of silyl-substituted vinylmetallic reagents with acetic and benzoic anhydride have been investigated as a general route to α,β-unsaturated ketones having a silyl group attached to the carbon–carbon double bond. The reaction has been found to be generally applicable for acetyl derivatives provided low temperatures are used but the reaction with benzoic anhydride gives poorer results. The i.r. and u.v. spectra of the ketones are discussed. The characterization of novel 1,4-dienes obtained as by-products in the syntheses is also described.

Expectations for Managing Contaminated Ground and Groundwater: Developing a Common View of NDA and Regulators

2009 ◽  
Author(s):  
Anna Clark
Keyword(s):  
Quality Management ◽  
Cost Effective ◽  
Nuclear Industry ◽  
Common View ◽  
Land Quality ◽  
Nuclear Decommissioning ◽  
Environmentally Responsible ◽  
Working Together ◽  
The Uk ◽  
Responsible Manner

The management of contaminated ground and groundwater is a notable contributor to dealing with the challenge we face in cleaning up the legacy of the UK’s civil nuclear industry in a safe, cost-effective and environmentally responsible manner. To facilitate this mission, the Nuclear Decommissioning Authority, Environmental Regulators and Safety Regulators are working together to develop common expectations for the management of contaminated ground and groundwater arising on and extending off nuclear licensed sites in the UK. The aims of this work are to: • set out shared expectations for land quality management, explaining any differing expectations where consensus is difficult; • interpret expectations to ensure they are clear and implementable, facilitating planning of programmes and deliverables; • provide a framework for dialogue against which progress in land quality management can be mapped; • promote positive action to manage land quality in a proportionate and sustainable manner to achieve consistent standards; and • identify whether areas of the regulatory framework or NDA contractual requirements warrant review and propose improvements for consideration, as appropriate. This paper outlines the process currently ongoing to identify the best way of achieving these aims in a manner that avoids compromising the respective statutory obligations, duties and functions of each party.

scholarly journals Inhibitory effect of okadaic acid derivatives on protein phosphatases. A study on structure-affinity relationship

1992 ◽  
Vol 284 (2) ◽  
pp. 539-544 ◽  
Author(s):  
A Takai ◽  
M Murata ◽  
K Torigoe ◽  
M Isobe ◽  
G Mieskes ◽  
...  
Keyword(s):  
Okadaic Acid ◽  
Structural Changes ◽  
Protein Phosphatases ◽  
Inhibitory Effect ◽  
Chemical Processes ◽  
Hydroxyl Group ◽  
Confidence Limits ◽  
X Ray ◽  
Structural Modifications

The effect of structural modifications of okadaic acid (OA), a polyether C38 fatty acid, was studied on its inhibitory activity toward type 1 and type 2A protein phosphatases (PP1 and PP2A) by using OA derivatives obtained either by isolation from natural sources or by chemical processes. The dissociation constant (Ki) for the interaction of OA with PP2A was estimated to be 30 (26-33) nM [median (95% confidence limits)]. The OA derivatives used and their affinity for PP2A, expressed as Ki (in brackets) were as follows: 35-methyl-OA (DTX1) [19 (12-25) pM], OA-9,10-episulphide (acanthifolicin) [47 (25-60) pM], 7-deoxy-OA [69 (31-138) pM], 14,15-dihydro-OA [315 (275-360) pM], 2-deoxy-OA [899 (763-1044) pM], 7-O-palmitoyl-OA [greater than 100 nM], 7-O-palmitoyl-DTX1 [greater than 100 nM], methyl okadate [much greater than 100 nM], 2-oxo-decarboxy-OA [much greater than 100 nM] and the C-15-C-38 fragment of OA [much greater than 100 nM]. The sequence of the affinity of these derivatives for PP1 was essentially the same as that observed with PP2A, although the absolute values of Ki were very different for the enzymes. The inhibitory effect of OA on PP2A was reversed by applying a murine monoclonal antibody against OA, which recognizes modifications of the 7-hydroxyl group of the OA molecule. It has been shown by n.m.r. spectroscopy and X-ray analysis that one end (C-1-C-24) of the OA molecule assumes a circular conformation. The present results suggest the importance of the conformation for the inhibitory action of OA on the protein phosphatases. The ratios of the Ki values for PP1 to that for PP2A, which were within the range 10(3)-10(4), tended to be smaller for the derivatives with lower affinity, indicating that the structural changes in OA impaired the affinity for PP2A more strongly than that for PP1.

Sign in / Sign up

Export Citation Format

Share Document