Offshore and Onshore Wave Energy Converters: Engineering and Environmental Features

In the last decade, extensive research has been carried out with the aim of designing new prototype devices that allow for the extraction of electricity from renewable energy sources, in order to contribute to a reduction in the use of nonrenewable resources, and thereby mitigate climate change impacts [...]

Recent Advances in Natural Functional Biopolymers and Their Applications of Electronic Skins and Flexible Strain Sensors

In order to replace nonrenewable resources and decrease electronic waste disposal, there is a rapidly rising demand for the utilization of reproducible and degradable biopolymers in flexible electronics. Natural biopolymers have many remarkable characteristics, including light weight, excellent mechanical properties, biocompatibility, non-toxicity, low cost, etc. Thanks to these superior merits, natural functional biopolymers can be designed and optimized for the development of high-performance flexible electronic devices. Herein, we provide an insightful overview of the unique structures, properties and applications of biopolymers for electronic skins (e-skins) and flexible strain sensors. The relationships between properties and sensing performances of biopolymers-based sensors are also investigated. The functional design strategies and fabrication technologies for biopolymers-based flexible sensors are proposed. Furthermore, the research progresses of biopolymers-based sensors with various functions are described in detail. Finally, we provide some useful viewpoints and future prospects of developing biopolymers-based flexible sensors.

Electrochemical biomass upgrading: degradation of glucose to lactic acid on a copper(ii) electrode

Biomass upgrading – the conversion of biomass waste into value-added products – provides a possible solution to reduce global dependency on nonrenewable resources.

Potassium Use Efficiency of Plants

There are many terms used to define aspects of potassium (K) use efficiency of plants. The terms used most frequently in an agricultural context are (1) agronomic K use efficiency (KUE), which is defined as yield per unit K available to a crop and is numerically equal to the product of (2) the K uptake efficiency (KUpE) of the crop, which is defined as crop K content per unit K available and (3) its K utilization efficiency (KUtE), which is defined as yield per unit crop K content. There is considerable genetic variation between and within plant species in KUE, KUpE, and KUtE. Root systems of genotypes with greatest KUpE often have an ability (1) to exploit the soil volume effectively, (2) to manipulate the rhizosphere to release nonexchangeable K from soil, and (3) to take up K at low rhizosphere K concentrations. Genotypes with greatest KUtE have the ability (1) to redistribute K from older to younger tissues to maintain growth and photosynthesis and (2) to reduce vacuolar K concentration, while maintaining an appropriate K concentration in metabolically active subcellular compartments, either by anatomical adaptation or by greater substitution of K with other solutes in the vacuole. Genetic variation in traits related to KUpE and KUtE might be exploited in breeding crop genotypes that require less K fertilizer. This could reduce fertilizer costs, protect the environment, and slow the exhaustion of nonrenewable resources.

Ecological Assessment of Clay Brick Manufacturing in China Using Emergy Analysis

Clay brick is a commonly used building material in China. Due to the enormous land destruction and excessive consumption of resources, such as materials and energy in the manufacture of clay brick, it is important to study its overall sustainability, i.e., in terms of impact on the environment, services, and economy. In this study, emergy analysis is employed, which offers a holistic perspective, unlike typical environmental studies. A series of emergy indices such as renewability rate (R%), nonrenewability rate (N%), unit emergy values (UEVs), emergy yield ratio (EYR), environmental loading ratio (ELR), and emergy sustainability index (ESI) were used to study manufacturing of clay brick. In addition to calculating UEVs of clay brick manufacturing in China (7.18 × 1012 sej/kg), our detailed analysis shows that the nonrenewable resources and imported energy have a dominant impact on the emergy contribution (50.6%) and within the nonrenewable resources, clay is the foremost item, accounting for 33.5% of local emergy inputs. Given different electricity UEVs, the change ranges of clay brick system UEVs are 14.9% (scenario 1), 7.24% (scenario 2), 8.91% (scenario 3), and 6.94% (scenario 4). Furthermore, several policy suggestions are discussed for improving the sustainability of the evaluated system, involving the energy structure adjustment, recycling material replacement, and promotion of energy-saving systems.

Post-consumer PET Bottle Recycling: Chemical Dose Optimization

Polyethylene terephthalate (PET) bottles are being used in our daily life and consequently go to the landfills after their use. Additionally, virgin PET resins are produced from nonrenewable resources, such as fossil fuels, whose reserves are depleting continuously. Therefore, to maintain ecological and environmental balances as well as for sustainable development, post-consumer PET (pcrPET) bottles should be recycled. Among many recycling processes, mechanical recycling of pcrPET is attractive due to lower cost involvement. One of the most crucial and important processes of mechanical recycling is hot washing for contaminants removal. Hot washing uses a cleaning solution made of caustic soda (NaOH) and detergent at elevated temperature. In this paper, caustic soda and FORYL LFO (FLO) detergent doses were changed gradually to investigate effective contaminants removal through colorimetric study. Finally, concentration vs. absorbance graphs from colorimetric study suggests that 2% NaOH and 2% FLO detergent is the optimum chemical dose at hot washing for pcrPET recycling.

Evaluation of Recycled Materials as Hydroponic Growing Media

Conventional soilless growing media, such as perlite, are mined from nonrenewable resources and can only be disposed of in landfills after limited use. There is a need to investigate novel, sustainable growing media adapted from waste or engineered to be reused over multiple cycles. This study investigated waste almond shells and a recycled plastic drainage plank as hydroponic growing media alternatives. Physiochemical properties were evaluated, and a germination and greenhouse growth trial was conducted to understand the effect these media have on production and nutritional quality of lettuce (Lactuca sativa L. cv. Catalogna Verde). Drought testing was carried out to understand how the media affected the lettuce’s response to water stress. In comparison to perlite, yields under regular irrigation were reduced by 52% in almond shells and 72% in plastic planks, although lettuce grown in almond shells still obtained commercially relevant yields. Reduced yields in almond shells were likely caused by the shell’s high salinity. Lettuce growth in plastic planks was limited by impeded root growth and low water-holding capacity. In conclusion, with minor alterations, almond shells could be used as a sustainable growing media alternative to perlite in hydroponic lettuce production. More research is needed to manufacture the planks to be conducive to plant growth.

The effectiveness of fiber-reinforced natural composites compared to the elastomer materials produced from nonrenewable resources in vibration transmission suppression

In this work, a number of tests were carried out to evaluate the effectiveness of the vibro-acoustic behavior composite consisting of a biodegradable polymer matrix (polylactid acid) and a filler in the form of natural flax fibers, with a moisture content of 2.03% after drying in 80°C for 4 h. To improve material dampening properties, polylactid acid was plasticized with polyethylene glycol 400 and triethyl citrate. The flax fiber content of the composite was 10, 20, and 30 wt%. Mechanical properties at bending and tensile were performed. For the measurement of vibro-acoustic suppression effectiveness, composite samples have been made to enable installation in the measurement system. The measuring system consisted of an unbalanced axial electric motor, resting on a steel frame placed on vibration suppressor. For comparison, the commercial grade vibration suppressor was used. In order to evaluate the vibration damping of the system by vibration suppressor, vibration engine frame vibration was forced by acceleration of the engine’s rotational speed to specific frequencies. It has been proven that the type of the plasticizer used in the composite changes the vibro-acoustic suppression parameter. Also, the length and the weight percentage of the fibers result in lower material damping values.