There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

http://faculty.wwu.edu/~shulld/ESCI%20101/Andrady2011Plastics.pdf

Microplastics in the marine environment

http://resodema.org/publications/publication9.pdf

The physical impacts of microplastics on marine organisms: a review.

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201001215

Antifouling coatings: recent developments in the design of surfaces that prevent fouling by proteins, bacteria, and marine organisms.

Synergism between natural products and antibiotics against infectious diseases

Several polymeric materials find application in biomedical implants and devices due to their superior physicochemical properties. The main requirement for these polymers is that they should be biocompatible, which means they prevent bacterial adhesion and are blood compatible. Many parameters contribute to the degree of biocompatibility. This paper discusses the mechanism of the formation of biofilms and lists the factors that influence the bacterial adhesion and haemocompatibility. Polymer surfaces are also modified to enhance adsorption of host cells. The physical, chemical and biological techniques are meant to modify the surface of the biomaterial but at the same time retain the key properties. The various polymer treatment processes have advantages and disadvantages and a few techniques have been proved to be both highly effective at treatment and found suitable for various in vivo environments. The current research focus pertaining to smart materials, biodegradable polymers, combinatorial chemistry, computational modelling and newer analytical techniques to understand polymer-cell interaction holds promise in designing better, cost effective and biocompatible polymers.

https://iopscience.iop.org/article/10.1088/1748-6041/3/3/034003/pdf

Biofilm formation, bacterial adhesion and host response on polymeric implants--issues and prevention.

Marine microbe-mediated biodegradation of low- and high-density polyethylenes

Polycarbonate is one of the most widely used engineering plastics because of its superior physical, chemical, and mechanical properties. Understanding the biodegradation of this polymer is of great importance to answer the increasing problems in waste management of this polymer. Aliphatic polycarbonates are known to biodegrade either through the action of pure enzymes or by bacterial whole cells. Very little information is available that deals with the biodegradation of aromatic polycarbonates. Biodegradation is governed by different factors that include polymer characteristics, type of organism, and nature of pretreatment. The polymer characteristics such as its mobility, tacticity, crystallinity, molecular weight, the type of functional groups and substituents present in its structure, and plasticizers or additives added to the polymer all play an important role in its degradation. The carbonate bond in aliphatic polycarbonates is facile and hence this polymer is easily biodegradable. On the other hand, bisphenol A polycarbonate contains benzene rings and quaternary carbon atoms which form bulky and stiff chains that enhance rigidity. Even though this polycarbonate is amorphous in nature because of considerable free volume, it is non-biodegradable since the carbonate bond is inaccessible to enzymes because of the presence of bulky phenyl groups on either side. In order to facilitate the biodegradation of polymers few pretreatment techniques which include photo-oxidation, gamma-irradiation, or use of chemicals have been tested. Addition of biosurfactants to improve the interaction between the polymer and the microorganisms, and blending with natural or synthetic polymers that degrade easily, can also enhance the biodegradation.

Biodegradation of aliphatic and aromatic polycarbonates.

Polyethylene and polypropylene are the two polyolefins with wide ranging applications. They are recalcitrant and hence remain inert to degradation and deterioration leading to their accumulation in the environment, and, therefore creating serious environmental problems. In this review, biodegradation of these two polymers under in vitro conditions is reported. An attempt has been made to cover the mechanism of biodegradation, the various bacterial and fungal organisms that have been reported for the same, methods adopted for the studies and different characterization techniques followed to measure the extent of degradation

/pdf/biodegradation-of-polyethylene-and-polypropylene-1ocjfh83t0.pdf

Mukesh Doble

Papers

Synergism between natural products and antibiotics against infectious diseases

Biofilm formation, bacterial adhesion and host response on polymeric implants--issues and prevention.

Marine microbe-mediated biodegradation of low- and high-density polyethylenes

Biodegradation of aliphatic and aromatic polycarbonates.

Biodegradation of polyethylene and polypropylene