The Effect of Nanofillers on the Functional Properties of Biopolymer-Based Films: A Review

Waste from non-degradable plastics is becoming an increasingly serious problem. Therefore, more and more research focuses on the development of materials with biodegradable properties. Bio-polymers are excellent raw materials for the production of such materials. Bio-based biopolymer films reinforced with nanostructures have become an interesting area of research. Nanocomposite films are a group of materials that mainly consist of bio-based natural (e.g., chitosan, starch) and synthetic (e.g., poly(lactic acid)) polymers and nanofillers (clay, organic, inorganic, or carbon nanostructures), with different properties. The interaction between environmentally friendly biopolymers and nanofillers leads to the improved functionality of nanocomposite materials. Depending on the properties of nanofillers, new or improved properties of nanocomposites can be obtained such as: barrier properties, improved mechanical strength, antimicrobial, and antioxidant properties or thermal stability. This review compiles information about biopolymers used as the matrix for the films with nanofillers as the active agents. Particular emphasis has been placed on the influence of nanofillers on functional properties of biopolymer films and their possible use within the food industry and food packaging systems. The possible applications of those nanocomposite films within other industries (medicine, drug and chemical industry, tissue engineering) is also briefly summarized

Testing the durability and function of road traffic management devices

Traffic management measures (vertical signs and horizontal marking, reflective elements) are used for guiding vehicles optically, indicating road mileage, marking objects in road gauge, marking vehicle and pedestrian safeguards and driver information and warning. This paper presents a synthesis of a literature study and the results of research conducted under stage one of the project LifeRoSE. The requirements for different traffic management measurements are described as well as durability and functionality tests and analysis of factors which influence durability and functionality of these measurements

Lighting requirements for pedestrian crossings – positive contrast

For many years now in Poland there has been a large number of road accidents at pedestrian crossings during night periods [5, 11]. One of the technical solutions that can improve this condition is the use of proper lighting for pedestrian crossings. The designated pedestrian crossing should be visible in different weather conditions and at different times of the day. In case of night vision restrictions use artificial lighting of pedestrian crossings. At the same time, lighting of pedestrian crossings should ensure: proper conditions for the driver to recognise the traffic situation and observe the pedestrian's silhouette, and for the pedestrian to observe the surroundings, pedestrian crossings and upcoming vehicles. The article gives an opinion on the proposal of lighting requirements for dedicated luminaires, realizing positive luminance contrast, used in the area of pedestrian crossings together with the proposed measurement grids. Quantitative requirements have been formulated taking into account the gradation of lighting classes resulting from the current lighting standard

KnotProt: a database of proteins with knots and slipknots

The protein topology database KnotProt, http://knotprot.cent.uw.edu.pl/, collects information about protein structures with open polypeptide chains forming knots or slipknots. The knotting complexity of the cataloged proteins is presented in the form of a matrix diagram that shows users the knot type of the entire polypeptide chain and of each of its subchains. The pattern visible in the matrix gives the knotting fingerprint of a given protein and permits users to determine, for example, the minimal length of the knotted regions (knot's core size) or the depth of a knot, i.e. how many amino acids can be removed from either end of the cataloged protein structure before converting it from a knot to a different type of knot. In addition, the database presents extensive information about the biological functions, families and fold types of proteins with non-trivial knotting. As an additional feature, the KnotProt database enables users to submit protein or polymer chains and generate their knotting fingerprint

Nanocomposite furcellaran films - The influence of nanofillers on functional properties of furcellaran films and effect on linseed oil preservation

Nanocomposite films that were based on furcellaran (FUR) and nanofillers (carbon quantum dots (CQDs), maghemite nanoparticles (MAN), and graphene oxide (GO)) were obtained by the casting method. The microstructure, as well as the structural, physical, mechanical, antimicrobial, and antioxidant properties of the films was investigated. The incorporation of MAN and GO remarkably increased the tensile strength of furcellaran films. However, the water content, solubility, and elongation at break were significantly reduced by the addition of the nanofillers. Moreover, furcellaran films containing the nanofillers exhibited potent free radical scavenging ability. FUR films with CQDs showed an inhibitory effect on the growth of Staphylococcus aureus and Escherichia coli. The nanocomposite films were used to cover transparent glass containers to study the potential UV-blocking properties in an oil oxidation test and compare with tinted glass. The samples were irradiated for 30 min. with UV-B and then analyzed for oxidation markers (peroxide value, free fatty acids, malondialdehyde content, and degradation of carotenoids). The test showed that covering the transparent glass with MAN films was as effective in inhibiting the oxidation as the use of tinted glass, while the GO and CQDs films did not inhibit oxidation. It can be concluded that the active nanocomposite films can be used as a desirable material for food packaging

Fermented juices as reducing and capping agents for the biosynthesis of size-defined spherical gold nanoparticles

Gold nanoparticles (AuNPs) are of scientific and industrial significance; however, the traditional synthesis methods employ toxic compounds. Hence, non-toxic and environmentally friendly AuNPs synthesis methods are of special interest. Here, AuNPs were produced using four solutions of fermented grape juices. UV/Vis absorption spectrophotometry and transmission electron microscopy indicated that AuNPs synthesized with a solution based on semi-sweet red grapes were mostly spherical with narrow size distribution (average diameter of 82.1 ± 36.2 nm). AuNPs of similar spherical morphology but smaller size were obtained using a solution based on semi-dry red grapes (57.1 ± 16.4 nm). A large variety of AuNPs shapes and broader size distribution were produced when solutions based on semi-sweet or dry white grapes were applied. In this case, the average sizes of the AuNPs were 271.6 ± 130.2 nm and 76.0 ± 47.2 nm, respectively. Using energy dispersive X-ray spectroscopy, Au, C, and O were detected, confirming formation of biogenic AuNPs in all cases. Mie theory calculations for AuNPs synthesized with the aid of solutions based on red grapes suggest that their optical properties are different and best suited for distinct downstream applications. Attenuated total reflectance Fourier transform infrared spectroscopy, the Folin-Ciocalteu assay, and the Bertrand's method were used to examine bioactive compounds present in the solutions applied for synthesis. Phenolics, and to a lesser extent reducing sugars, were identified as likely playing a significant role in reduction and stabilization of the AuNPs. These results display the great potential of these solutions for green synthesis of size defined AuNPs, and illustrate that different grape varieties may be used to obtain AuNPs with unique properties. Keywords: Nanostructures, Bioreduction process, Phenolics, Reducing sugars, Mie scatterin

Review of methods for assessing traffic conditions on basic motorway and expressway sections

Motorways and expressways are the core of each country’s road system. Road planning, design and management requires tools to ensure that roads have the right geometry, traffic layout and equipment. These include methods for capacity estimation and assessing traffic conditions. Because the paper focusses on the basic segments of motorways and expressways (sections located between interchanges and outside of their influence), its objective is to review and compare methods used worldwide and establish whether their assumptions or procedures could be used in Polish conditions. Four methods were selected for analysis: US, German, Swedish and Dutch. Theoretical and empirical comparisons were conducted, with the latter using data from sections of motorways and expressways in Poland collected in the RID-2B project. The results of the analyses showed important differences between the methods in terms of procedures for traffic conditions assessment, assumptions, base capacities, traffic conditions measures, factors or speed-flow models. Significant differences were also found when traffic parameter estimates made with particular methods were compared to real data from Polish roads. The results contributed to the development of Poland’s new method, to be prepared as a result of the RID-2B project. It was concluded that none of the analysed methods can be directly adopted to Polish conditions. An important conclusion is the need to include Poland-specific motorway speed limits and procedure for determining free-flow speed, the basis for further analyses

Chitosan for Seafood Processing and Preservation

WOS: 000489262400003Recently, a greater attention has been directed to a more effective exploitation of chitin, the second most available polysaccharide in crustacean's products. The shellfish processing industry produces unusable waste, thus posing a practical challenge. Approximately 75% of the total weight of crustaceans ends up as waste and there are actually no acceptable waste management solutions. Thus, the extraction of chitin from the shells of crustaceans, such as shrimps, crabs, prawns, lobster or krill, and its further use in the unprocessed or processed condition minimizes waste and produces valuable compounds. Chitosan, a deacetylated derivative of chitin, has many functional properties which can be used for various applications such as processing, preservation and food additives. Recently, sustainable and cost-effective methods for chitosan preparation and use have been developed. Methods of chitosan application, such as edible coatings, direct addition to the batter or tumbling in chitosan solution, allows chitin use for almost every type of seafood. Chitosan exhibits properties including antioxidant, antimicrobial and film-forming properties, and thus yields promising results as food additive. Moreover, the use of chitosan for seafood products is solving two major spoilage issues: increased oxidation and microbiological spoilage. Indeed, we observe decreased deterioration of sensory scores during storage, and prolonged shelf-life seafood products treated with chitosan

Development of direct-current, atmospheric-pressure, glow discharges generated in contact with flowing electrolyte solutions for elemental analysis by optical emission spectrometry

Direct-current, atmospheric-pressure, glow discharge (dc-APGD) generated in contact with flowing sample solutions is a new, very promising excitation source for analytical optical emission spectrometry, due to its low maintenance requirements and its analytical performance. Since analyzed solutions act as liquid cathodes, this discharge system is useful for the direct determination of elements dissolved in solutions without having to produce their aerosols by pneumatic nebulization. The review presents different systems and designs of dc-APGD generated with the liquid cathode applied to spectrochemical analysis in the past 20 years. We discuss the effect of experimental conditions on analytical response and performance of the discharge. We include analytical figures of merit obtained with different discharge systems and their application to the analysis of environmental and biological samples containing various trace elements.