Search results for "NEWA"
showing 10 items of 2491 documents
The Place of Energy Security in the National Security Framework: An Assessment Approach
2022
The term “energy security” is used almost everywhere in economic and political discussions related to energy supply. However, different authors use different meanings to express the concept of energy security. Quite often, this term is used to give more importance or relevance to issues that are often not inherently related to energy security. Attempts to define the essence of the concept of “energy security” have hitherto not been systematic and are characterized by a variety of approaches, and some insufficient justification especially in the aspect of state national security is notable. Our contribution to the discourse development is the consideration of energy s…
Intellectual Structure of the Belt and Road Initiative Research: A Scientometric Analysis and Suggestions for a Future Research Agenda
2020
China’s Belt and Road Initiative (BRI) has attracted increasing attention worldwide since its inception in 2013. Although the research is fast increasing in terms of publications, there is a lack of knowledge about the intellectual structure, research trends, and appropriate theories underpinning. Using bibliometric data from 1583 articles from 2013 to 2019 in the Web of Science and Scopus databases, we used bibliometric techniques and scientometric analyses to identify and analyze the intellectual structure, hotspots, and emerging trends in this field. We identified 18 clusters that we categorized into three groups for thematic discussion. Research gaps and future research directions were …
Making natural products from renewable feedstocks: back to the roots?
2019
Covering: up to mid-2019 This review highlights the utilization of biomass-derived building blocks in the total synthesis of natural products. An overview over several renewable feedstock classes, namely wood/lignin, cellulose, chitin and chitosan, fats and oils, as well as terpenes, is given, covering the time span from the initial beginning of natural product synthesis until today. The focus is put on the origin of the employed carbon atoms and on the nature of the complex structures that were assembled therefrom. The emerging trend of turning away from petrochemically derived starting materials back to bio-based resources, just as seen in the early days of total synthesis, shall be demon…
Influence of synthesis conditions on the performance of chitosan–Heteropolyacid complexes as membranes for low temperature H2–O2 fuel cell
2015
Flat, free-standing chitosan/phosphotungstic acid (PTA) polyelectrolyte membranes were prepared by in-situ ionotropic gelation process at room temperature on porous alumina support firstly impregnated by H3PW12O40. Scanning electron microscopy revealed the formation of compact and homogeneous membranes, whose thickness resulted to be dependent on chitosan concentration and reticulation time. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) evidenced the formation of almost amorphous membrane without appreciable concentration of not protonated NH2 groups and PTA3- ions with preserved Keggin structure. Membranes were tested as proton conductor in low temperature H2-O2 fuel…
Chitosan-phosphotungstic acid complex as membranes for low temperature H2-O2 fuel cell
2015
Abstract Free-standing Chitosan/phosphotungstic acid polyelectrolyte membranes were prepared by an easy and fast in-situ ionotropic gelation process performed at room temperature. Scanning electron microscopy was employed to study their morphological features and their thickness as a function of the chitosan concentration. The membrane was tested as proton conductor in low temperature H 2 –O 2 fuel cell allowing to get peak power densities up to 350 mW cm −2 . Electrochemical impedance measurements allowed to estimate a polyelectrolyte conductivity of 18 mS cm −1 .
Microalgae cultivation in wastewater: nutrient removal from anaerobic membrane bioreactor effluent
2012
This study investigated the removal of nitrogen and phosphorus from the effluent of a submerged anaerobic membrane bioreactor (SAnMBR) by means of a lab-scale photobioreactor in which algae biomass was cultured in a semi-continuous mode for a period of 42 days. Solids retention time was 2 days and a stable pH value in the system was maintained by adding CO2. Nitrogen and phosphorus concentrations in the SAnMBR effluent fluctuated according to the operating performance of the bioreactor and the properties of its actual wastewater load. Despite these variations, the anaerobic effluent proved to be a suitable growth medium for microalgae (mean biomass productivity was 234 mgl(-1) d(-1)), achie…
Ultrasound-assisted green solvent extraction of high-added value compounds from microalgae Nannochloropsis spp.
2015
Abstract The aim of this work was to investigate ultrasound (US)-assisted green solvent extraction of valuable compounds from the microalgae Nannochloropsis spp. Individual green solvents (water, ethanol (EtOH), dimethyl sulfoxide (DMSO)) and binary mixture of solvents (water-DMSO and water-EtOH) were used for the extraction procedures. Maximum total phenolic compounds yield ( Y p ≈ 0.33) was obtained after US pre-treatment ( W = 400 W, 15 min), being almost 5-folds higher compared to that found for the untreated samples and aqueous extraction ( Y p ≈ 0.06). The highest yield of total chlorophylls ( Y c ≈ 0.043) was obtained after US ( W = 400 W, 7.5 min), being more than 9-folds highe…
Preparation of Pd coated anodic alumina membranes for gas separation media
2007
Different procedures of Pd electroless deposition onto anodic alumina membranes were investigated to form a dense metal layer covering pores. The main difficulty was related to the amorphous nature of anodic alumina membranes, determining low chemical stability in solutions at pH > 9, where Pd plating works more efficiently. As a consequence, it was necessary to find the operative conditions allowing Pd deposition without damaging the membrane: to reduce alumina dissolution, the plating bath was buffered at pH 8.5 by addition of either NaHCO 3 or Na 2 B 4 O 7 ·H 2 O. Acceptable conversion of Pd was found after a deposition time of 3 min. Single and multiple deposition steps (each lasting 3 …
The Sustainability of Reclaimed Asphalt as a Resource for Road Pavement Management through a Circular Economic Model
2019
The transition of the road engineering industry to a circular way of doing business requires more efficient and sustainable resources, energy, and waste management. The rates in which reclaimed asphalt is being recycled or reused in the asphalt mixture production process constitutes a crucial parameter in this transition. This paper aims at establishing a further step towards the combined circularity and sustainability of asphalt pavements, by introducing a framework for quantifying their Material Circularity Index. The framework is based on the methodology proposed by the Ellen MacArthur Foundation and accordingly tailored for the context of asphalt pavements. This study, thus, attempts to…
European National Road Authorities and Circular Economy: An Insight into Their Approaches
2020
The pavement engineering industry, having realized the significance of the impacts that it imposes on the environment through the production, construction and management of its products and assets, has been driven towards a more sustainable and circular way of operating. This has partly been through asphalt recycling, which is an area that many road authorities have prioritized. However, not all the National Road Authorities (NRAs) and/or sector stakeholders seem to be adequately familiar with the Circular Economy (CE) concept. This paper attempts to assist the transition of NRAs to a more circular way of doing business, by analyzing the current situation of CE within national/regional auth…