Biodegradability standards for carrier bags and plastic films in aquatic environments: a critical review

Plastic litter is encountered in aquatic ecosystems across the globe, including polar environments and the deep sea. To mitigate the adverse societal and ecological impacts of this waste, there has been debate on whether ‘biodegradable’ materials should be granted exemptions from plastic bag bans and levies. However, great care must be exercised when attempting to define this term, due to the broad and complex range of physical and chemical conditions encountered within natural ecosystems. Here, we review existing international industry standards and regional test methods for evaluating the biodegradability of plastics within aquatic environments (wastewater, unmanaged freshwater and marine habitats). We argue that current standards and test methods are insufficient in their ability to realistically predict the biodegradability of carrier bags in these environments, due to several shortcomings in experimental procedures and a paucity of information in the scientific literature. Moreover, existing biodegradability standards and test methods for aquatic environments do not involve toxicity testing or account for the potentially adverse ecological impacts of carrier bags, plastic additives, polymer degradation products or small (microscopic) plastic particles that can arise via fragmentation. Successfully addressing these knowledge gaps is a key requirement for developing new biodegradability standard(s) for lightweight carrier bags

Thermal, mechanical and microstructural analysis of concrete containing microencapsulated phase change materials

This paper studies the thermal, mechanical and microstructural aspects of concrete containing different amounts of microencapsulated phase change materials (PCMs). In addition, numerical simulation is carried out to study the potential application of PCM-modified concrete for reduction in summer surface temperature. It is shown that increasing PCM content in concrete led to lower thermal conductivity and an increase in the heat storage ability of concrete. However, the compressive and flexural strength of concrete significantly decreased. Microstructural analysis showed that PCMs appear to remain intact during mixing; however, PCM particles appear to fail by bursting under loading, creating hemispherical voids and crack initiation points as well as possible entrapped air behaviour. The result of numerical simulation revealed that reduction in summer concrete pavement surface temperature by several degrees was possible, with implications for reduction in concrete thermal stresses, shrinkage and urban heat island effect

Damage evaluation during installation of geosynthetics used in asphalt pavements

Geosynthetics are commonly used as anti-reflective cracking systems in asphalt pavements. The rehabilitation design methods use the characteristics of as-received geosynthetics as inputs. However, these materials undergo physical damage during their installation due to mechanical and thermal loads which currently are not taken into account in the design processes. These loads can produce a reduction in geosynthetic strength and therefore, it is necessary to know the secant modulus after installation in order to improve the pavement design incorporating these materials. The secant modulus of a material indicates its initial stiffness. This paper describes an experimental study of damage due to installation of five different geosynthetics using three different procedures: (i) mechanical damage induced in the laboratory considering the action of aggregates, (ii) in situ mechanical and thermal damage due to actual installation in a test section, and (iii) a new mechanical and thermal damage experimental test developed with the aim of reproducing the real installation conditions. The main results of the study indicate that the obtained secant modulus of the tested geosynthetics reduced after applying the three damage procedures, and the loss of properties differed depending on the type and constitutive material and on the applied damage procedure.This investigation was supported by the research Project ‘Rehabilitation of roads and highways (REHABCAR)’ file number IPT-370000–2010–029, led by DRAGADOS (ACS Group), in collaboration with GEOCISA and ASFALTOS AUGUSTA among others. The project has been funded by the Ministry of Economy and Competitiveness (MINECO) within the National Plan for Scientific Research, Development and Innovation 2008–2011 (INNPACTO 2010) and the European Union under ERDF Funds (European Regional Development Fund)

Replacement of fish meal with a matrix of organic plant proteins in organic trout (Oncorhynchus mykiss) feed, and the effects on nutrient utilization and fish performance

This study examined the effects on nutrient utilization and fish performance when replacing 16, 31, and 47% of fish meal protein (corresponding to replacing 15, 29 and 44%, respectively, of total dietary protein) with a fixed matrix of organic pea, horsebean and rapeseed plant protein concentrates (PPC) in a ratio of 1.07:1.00:0.66. Four iso-energetic and iso-nitrogenous diets were produced to include 0, 136, 274 or 410 g kg-1 of the organic PPC matrix, respectively. The organic protein ingredients were chosen based on their high protein content, and the matrix was established to mirror the amino acid composition of fish meal. The plant ingredients were dried, dehulled, grinded and air classified in accordance with the European Union Commission Regulation on organic aquaculture production, increasing the protein concentrations up to 577 g kg-1 dry matter. Two experiments were carried out using juvenile rainbow trout (Oncorhynchus mykiss): 1) a digestibility study to examine the apparent digestibility of protein, lipid, nitrogen-free extract (NFE), total phosphorus and phytate-phosphorus, followed by a water sampling period to determine the output of nitrogen and phosphorus and enabling the setup of nitrogen and phosphorus mass-balances; and 2) a 57 days growth study including 3 growth periods each of 19 days and using pit-tagged fish. Substituting fish meal with organic PPC significantly increased the apparent digestibility coefficient (ADC) of protein and lipid (P<0.008) at the highest PPC inclusion level, while there was a significant (P<0.044) decrease in the ADC of NFE with increasing PPC inclusion level. The apparent digestibility coefficient of phytate-phosphorus was significantly lower (P<0.005) at the highest PPC inclusion level compared to the fish meal control diet. The mass-balances revealed a significant increase in the excretion of ammonium-nitrogen (NH4N, P< 0.017) at the two highest PPC inclusion levels and a decrease in phosphorus (P<0.009) excretion at the highest organic PPC inclusion level. There was no overall effect on the specific growth rates (SGRs) or feed conversion ratios (FCRs). The study thus demonstrated that it is possible to replace fish meal by 47% organic PPC without compromising rainbow trout performance. However, the results also indicated that it will be difficult to replace much more than this as long as supplementation with synthetic amino acids and exogenous phytase is not allowed in organic feed

Direct load monitoring of rolling bearing contacts using ultrasonic time of flight

The load applied by each rolling element on a bearing raceway controls friction, wear and service life. It is possible to infer bearing load from load cells or strain gauges on the shaft or bearing housing. However, this is not always simply and uniquely related to the real load transmitted by rolling elements directly to the raceway. Firstly, the load sharing between rolling elements in the raceway is statically indeterminate, and secondly, in a machine with non-steady loading, the load path is complex and highly transient being subject to the dynamic behaviour of the transmission system. This study describes a method to measure the load transmitted directly by a rolling element to the raceway by using the time of flight (ToF) of a reflected ultrasonic pulse. A piezoelectric sensor was permanently bonded onto the bore surface of the inner raceway of a cylindrical roller bearing. The ToF of an ultrasonic pulse from the sensor to the roller-raceway contact was measured. This ToF depends on the speed of the wave and the thickness of the raceway. The speed of an ultrasonic wave changes with the state of the stress, known as the acoustoelastic effect. The thickness of the material varies when deflection occurs as the contacting surfaces are subjected to load. In addition, the contact stiffness changes the phase of the reflected signal and in simple peak-to-peak measurement, this appears as a change in the ToF. In this work, the Hilbert transform was used to remove this contact dependent phase shift. Experiments have been performed on both a model line contact and a single row cylindrical roller bearing from the planet gear of a wind turbine epicyclic gearbox. The change in ToF under different bearing loads was recorded and used to determine the deflection of the raceway. This was then related to the bearing load using a simple elastic contact model. Measured load from the ultrasonic reflection was compared with the applied bearing load with good agreement. The technique shows promise as an effective method for load monitoring in real-world bearing applications

Noise and disturbance caused by vehicles crossing cattle grids: comparison of installations

Cattle grids are used on roads and tracks to prevent grazing animals from leaving an open space without fencing onto a more controlled area where access to the road from surrounded land is more limited. They are widely used in the UK at the entrances to common and moorland areas where animals are free to roam, but also on private drive entrances. Typically, they consist of a series of metal bars across the road that are spaced so that an animal’s legs would fall through the gaps if it attempted to cross. Below the grid is a shallow pit that is intended to further deter livestock from using that particular crossing point. The sound produced as vehicles cross these devices is a characteristic low frequency “brrrr” where the dominant frequencies relates to the bar passage frequency under the tyres. The sound can be disturbing to riders and their horses and walkers and residents living close by as evidenced by press reports and the need to consider noise aspects in planning for new installations. For this reason and due to the lack of available information on the size and nature of the problem measurements and recordings have been made at a number of sites in Yorkshire in the UK. In addition, questionnaire surveys of residents living close by and façade measurements have also been used to gauge impact. Results show that there is a wide variation in the maximum noise level produced by cattle grids of apparently similar design. This can be related to impact noise produced by the movement of all or part of the grid as the frame comes under impulsive loading as the vehicle crosses. It was further established that some residents living close to the cattle grids were disturbed by the noise, and in some cases vibration, and wanted them removed or suitably modified

Advances in standardization of laboratory measurement procedures: implications for measuring biomarkers of folate and vitamin B-12 status in NHANES1234

Population studies such as NHANES analyze large numbers of laboratory measurements and are often performed in different laboratories using different measurement procedures and over an extended period of time. Correct clinical and epidemiologic interpretations of the results depend on the accuracy of those measurements. Unfortunately, considerable variability has been observed among assays for folate, vitamin B-12, and related biomarkers. In the past few decades, the science of metrology has advanced considerably, with the development of improved primary reference measurement procedures and high-level reference materials, which can serve as the basis for accurate measurement. A rigorous approach has been established for making field methods traceable to the highest-level reference measurement procedures and reference materials. This article reviews some basic principles of metrology and describes their recent application to measurements of folate and vitamin B-12

Ecological policy in oil-gas complexes, HSE MS implementation in oil and gas company

The paper considers the following issues: HSE MS international standard implementation in oil and gas industry, taking into account international practices; implementation of standards in oil and gas companies; policy in the field of environmental protection and occupational health and safety; achievement of planned indicators and targets in environmental protection and occupational health and safety