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Challenges, Volume 8, Issue 1 (June 2017)

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Editorial

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Open AccessEditorial Acknowledgement to Reviewers of Challenges in 2016
Challenges 2017, 8(1), 2; doi:10.3390/challe8010002
Received: 11 January 2017 / Accepted: 11 January 2017 / Published: 11 January 2017
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Open AccessEditorial ADP-Ribosylation Reactions in Animals, Plants, and Bacteria
Challenges 2017, 8(1), 14; doi:10.3390/challe8010014
Received: 15 June 2017 / Revised: 15 June 2017 / Accepted: 15 June 2017 / Published: 19 June 2017
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Research

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Open AccessArticle Expert System for Bomb Factory Detection by Networks of Advance Sensors
Challenges 2017, 8(1), 1; doi:10.3390/challe8010001
Received: 31 October 2016 / Revised: 23 December 2016 / Accepted: 26 December 2016 / Published: 3 January 2017
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Abstract
(1) Background: Police forces and security administrations are nowadays considering Improvised explosives (IEs) as a major threat. The chemical substances used to prepare IEs are called precursors, and their presence could allow police forces to locate a bomb factory where the on-going manufacturing
[...] Read more.
(1) Background: Police forces and security administrations are nowadays considering Improvised explosives (IEs) as a major threat. The chemical substances used to prepare IEs are called precursors, and their presence could allow police forces to locate a bomb factory where the on-going manufacturing of IEs is carried out. (2) Methods: An expert system was developed and tested in handling signals from a network of sensors, allowing an early warning. The expert system allows the detection of one precursor based on the signal provided by a single sensor, the detection of one precursor based on the signal provided by more than one sensor, and the production of a global alarm level based on data fusion from all the sensors of the network. (3) Results: The expert system was tested in the Italian Air Force base of Pratica di Mare (Italy) and in the Swedish Defence Research Agency (FOI) in Grindsjön (Sweden). (4) Conclusion: The performance of the expert system was successfully evaluated under relevant environmental conditions. The approach used in the development of the expert system allows maximum flexibility in terms of integration of the response provided by any sensor, allowing to easily include in the network all possible new sensors. Full article
(This article belongs to the Special Issue Challenges in New Technologies for Security)
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Open AccessArticle Ice XVII as a Novel Material for Hydrogen Storage
Challenges 2017, 8(1), 3; doi:10.3390/challe8010003
Received: 31 December 2016 / Revised: 28 January 2017 / Accepted: 1 February 2017 / Published: 8 February 2017
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Abstract
Hydrogen storage is one of the most addressed issues in the green-economy field. The latest-discovered form of ice (XVII), obtained by application of an annealing treatment to a H2-filled ice sample in the C0-phase, could be inserted in the
[...] Read more.
Hydrogen storage is one of the most addressed issues in the green-economy field. The latest-discovered form of ice (XVII), obtained by application of an annealing treatment to a H 2 -filled ice sample in the C 0 -phase, could be inserted in the energy-storage context due to its surprising capacity of hydrogen physisorption, when exposed to even modest pressure (few mbars at temperature below 40 K), and desorption, when a thermal treatment is applied. In this work, we investigate quantitatively the adsorption properties of this simple material by means of spectroscopic and volumetric data, deriving its gravimetric and volumetric capacities as a function of the thermodynamic parameters, and calculating the usable capacity in isothermal conditions. The comparison of ice XVII with materials with a similar mechanism of hydrogen adsorption like metal-organic frameworks shows interesting performances of ice XVII in terms of hydrogen content, operating temperature and kinetics of adsorption-desorption. Any application of this material to realistic hydrogen tanks should take into account the thermodynamic limit of metastability of ice XVII, i.e., temperatures below about 130 K. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Open AccessArticle New Studies of the Physical Properties of Metallic Amorphous Membranes for Hydrogen Purification
Challenges 2017, 8(1), 4; doi:10.3390/challe8010004
Received: 22 December 2016 / Revised: 6 February 2017 / Accepted: 7 February 2017 / Published: 10 February 2017
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Abstract
Amorphous metallic membranes display promising properties for hydrogen purification up to an ultrapure grade (purity > 99.999%). The hydrogen permeability through amorphous membranes has been widely studied in the literature. In this work we focus on two additional properties, which should be considered
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Amorphous metallic membranes display promising properties for hydrogen purification up to an ultrapure grade (purity > 99.999%). The hydrogen permeability through amorphous membranes has been widely studied in the literature. In this work we focus on two additional properties, which should be considered before possible application of such materials: the propensity to crystallize at high temperatures should be avoided, as the crystallized membranes can become brittle; the hydrogen solubility should be high, as solubility and permeability are proportional. We investigate the crystallization process and the hydrogen solubility of some membranes based on Ni, Nb, and Zr metals, as a function of Zr content, and with the addition of Ta or B. The boron doping does not significantly affect the crystallization temperature and the thermal stability of the membrane. However, the hydrogen solubility for p ~7 bar is as high as H/M ~0.31 at T = 440 °C and H/M ~0.27 at T = 485 °C. Moreover, the membrane does not pulverize even after repeated thermal cycles and hydrogenation processes up to 485 °C and 7 bar, and it retains its initial shape. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Open AccessArticle Ionic Mobility and Phase Transitions in Perovskite Oxides for Energy Application
Challenges 2017, 8(1), 5; doi:10.3390/challe8010005
Received: 30 December 2016 / Accepted: 7 February 2017 / Published: 13 February 2017
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Abstract
Perovskite oxides find applications or are studied in many fields related to energy production, accumulation and saving. The most obvious application is oxygen or proton conductors in fuel cells (SOFCs), but the (anti)ferroelectric compositions may find application in high energy capacitors for energy
[...] Read more.
Perovskite oxides find applications or are studied in many fields related to energy production, accumulation and saving. The most obvious application is oxygen or proton conductors in fuel cells (SOFCs), but the (anti)ferroelectric compositions may find application in high energy capacitors for energy storage, efficient electrocaloric cooling, and electromechanical energy harvesting. In SOFCs, the diffusion of O vacancies and other mobile ionic species, such as H+, are at the base of the functioning of the device, while in the other cases they constitute unwanted defects that reduce the performance and life-time of the device. Similarly, the (anti)ferroelectric phase transitions are a requisite for the use of some types of devices, but the accompanying domain walls can generate extended defects detrimental to the life of the material, and structural phase transformations should be avoided in SOFCs. All these phenomena can be studied by mechanical spectroscopy, the measurement of the complex elastic compliance as a function of temperature and frequency, which is the mechanical analogue of the dielectric susceptibility, but probes the elastic response and elastic dipoles instead of the dielectric response and electric dipoles. The two techniques can be combined to provide a comprehensive picture of the material properties. Examples are shown of the study of structural transitions and hopping and tunnelling processes of O vacancies and H in the ion conductor BaCe1-xYxO3-x and in SrTiO3-x, and of the aging and fatigue effects found in PZT at compositions where the ferro- and antiferroelectric states coexist. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Open AccessArticle Tie-Up Cycles in Long-Term Mating. Part II: Fictional Narratives and the Social Cognition of Mating
Challenges 2017, 8(1), 6; doi:10.3390/challe8010006
Received: 23 October 2016 / Accepted: 9 February 2017 / Published: 20 February 2017
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Abstract
In the first part of this paper, we have introduced a novel theoretical approach to mating dynamics, known as Tie-Up Theory (TU). In this second part, in the context of the bio-cultural approach to literature, that assigns to fictional narratives an important valence
[...] Read more.
In the first part of this paper, we have introduced a novel theoretical approach to mating dynamics, known as Tie-Up Theory (TU). In this second part, in the context of the bio-cultural approach to literature, that assigns to fictional narratives an important valence of social cognition, we apply the conceptual tools presented in the first part to the analysis of mating-related interaction dynamics in some blockbuster Hollywood movies from WWII to today. The interaction dynamics envisioned by our theory accurately reflect, to a significant level of detail, the narrative development of the movies under exam from the viewpoint of the mating dynamics of the couple of main characters, accounting for the specific reasons that lead them to react to certain situations via certain behaviors, and for the reasons why such behaviors lead to certain outcomes. Our analysis seems thus to bring some further legitimacy to the bio-cultural foundation of the narrative structure of the movies that we analyze, and moreover to the idea that it is possible to ‘inquire’ characters about their choices according to the narratological-experimental lines suggested by some proponents of the bio-cultural approach. Full article
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Open AccessArticle A Study of the Conformers of the (Nonafluorobutanesulfonyl)imide Ion by Means of Infrared Spectroscopy and Density Functional Theory (DFT) Calculations
Challenges 2017, 8(1), 7; doi:10.3390/challe8010007
Received: 30 January 2017 / Revised: 16 February 2017 / Accepted: 20 February 2017 / Published: 22 February 2017
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Abstract
Pyrrolidinium-based ionic liquids with anions of the per(fluoroalkylsulfonyl)imide family are particularly interesting for their use as electrolytes in lithium batteries. These ions have several geometric isomers and the presence of different ion conformers and their distribution affects the ILs (Ionic liquids) physical and
[...] Read more.
Pyrrolidinium-based ionic liquids with anions of the per(fluoroalkylsulfonyl)imide family are particularly interesting for their use as electrolytes in lithium batteries. These ions have several geometric isomers and the presence of different ion conformers and their distribution affects the ILs (Ionic liquids) physical and chemical properties. In the present work, we report the temperature dependence of the infrared spectra of the N-butyl-N-methyl-pyrrolidinium(trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (PYR14IM14) ionic liquid; DFT (Density Functional Theory) calculations performed with different models provides indications about the IM14 conformers and their vibrational spectra. Moreover the temperature dependence of the intensity of the lines identified as markers of different conformers provide indications about the conformers’ distribution and the difference of their enthalpy in the liquid phase. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Open AccessArticle Case Studies of Energy Storage with Fuel Cells and Batteries for Stationary and Mobile Applications
Challenges 2017, 8(1), 9; doi:10.3390/challe8010009
Received: 31 January 2017 / Revised: 13 March 2017 / Accepted: 20 March 2017 / Published: 22 March 2017
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Abstract
In this paper, hydrogen coupled with fuel cells and lithium-ion batteries are considered as alternative energy storage methods. Their application on a stationary system (i.e., energy storage for a family house) and a mobile system (i.e., an unmanned aerial vehicle) will be investigated.
[...] Read more.
In this paper, hydrogen coupled with fuel cells and lithium-ion batteries are considered as alternative energy storage methods. Their application on a stationary system (i.e., energy storage for a family house) and a mobile system (i.e., an unmanned aerial vehicle) will be investigated. The stationary systems, designed for off-grid applications, were sized for photovoltaic energy production in the area of Turin, Italy, to provide daily energy of 10.25 kWh. The mobile systems, to be used for high crane inspection, were sized to have a flying range of 120 min, one being equipped with a Li-ion battery and the other with a proton-exchange membrane fuel cell. The systems were compared from an economical point of view and a life cycle assessment was performed to identify the main contributors to the environmental impact. From a commercial point of view, the fuel cell and the electrolyzer, being niche products, result in being more expensive with respect to the Li-ion batteries. On the other hand, the life cycle assessment (LCA) results show the lower burdens of both technologies. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Open AccessArticle Electrochemical Sensor for Explosives Precursors’ Detection in Water
Challenges 2017, 8(1), 10; doi:10.3390/challe8010010
Received: 9 February 2017 / Revised: 16 March 2017 / Accepted: 17 March 2017 / Published: 22 March 2017
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Abstract
Although all countries are intensifying their efforts against terrorism and increasing their mutual cooperation, terrorist bombing is still one of the greatest threats to society. The discovery of hidden bomb factories is of primary importance in the prevention of terrorism activities. Criminals preparing
[...] Read more.
Although all countries are intensifying their efforts against terrorism and increasing their mutual cooperation, terrorist bombing is still one of the greatest threats to society. The discovery of hidden bomb factories is of primary importance in the prevention of terrorism activities. Criminals preparing improvised explosives (IE) use chemical substances called precursors. These compounds are released in the air and in the waste water during IE production. Tracking sources of precursors by analyzing air or wastewater can then be an important clue for bomb factories’ localization. We are reporting here a new multiplex electrochemical sensor dedicated to the on-site simultaneous detection of three explosive precursors, potentially used for improvised explosive device preparation (hereafter referenced as B01, B08, and B15, for security disclosure reasons and to avoid being detrimental to the security of the counter-explosive EU action). The electrochemical sensors were designed to be disposable and to combine ease of use and portability in a screen-printed eight-electrochemical cell array format. The working electrodes were modified with different electrodeposited metals: gold, palladium, and platinum. These different coatings giving selectivity to the multi-sensor through a “fingerprint”-like signal subsequently analyzed using partial least squares-discriminant analysis (PLS-DA). Results are given regarding the detection of the three compounds in a real environment and in the presence of potentially interfering species. Full article
(This article belongs to the Special Issue Challenges in New Technologies for Security)
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Open AccessArticle About the Purification Route of Ionic Liquid Precursors
Challenges 2017, 8(1), 11; doi:10.3390/challe8010011
Received: 26 December 2016 / Revised: 7 March 2017 / Accepted: 22 March 2017 / Published: 27 March 2017
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Abstract
In this work a purification route of precursors for ionic liquids tailored to electrochemical energy storage systems is reported and described. The study was carried out on the N-butyl-N-methylpyrrolidinium bromide (PYR14Br) precursor, which represents the intermediate product of
[...] Read more.
In this work a purification route of precursors for ionic liquids tailored to electrochemical energy storage systems is reported and described. The study was carried out on the N-butyl-N-methylpyrrolidinium bromide (PYR14Br) precursor, which represents the intermediate product of the synthesis process of the N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) hydrophobic ionic liquid. The target is to develop an easy and cost-effective approach for efficiently purifying several kinds of ionic liquid precursors and determining their purity content. The PYR14Br precursor was synthesized through an eco-friendly preparation procedure, which requires water as the only processing solvent, and purified through sorbent materials, such as activated charcoal and alumina. The effect of the treatment/nature/content of sorbents and processing temperature/time was investigated. The impurity content was detected by UV-VIS spectrophotometry measurements. Additionally, a correlation between the measured absorbance and the content of impurities within the precursor was obtained. The purity level of the precursor was seen to play a key role in the electrochemical performance of the ionic liquids. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Review

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Open AccessReview Hydrides as High Capacity Anodes in Lithium Cells: An Italian “Futuro in Ricerca di Base FIRB-2010” Project
Challenges 2017, 8(1), 8; doi:10.3390/challe8010008
Received: 30 January 2017 / Revised: 7 March 2017 / Accepted: 10 March 2017 / Published: 16 March 2017
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Abstract
Automotive and stationary energy storage are among the most recently-proposed and still unfulfilled applications for lithium ion devices. Higher energy, power and superior safety standards, well beyond the present state of the art, are actually required to extend the Li-ion battery market to
[...] Read more.
Automotive and stationary energy storage are among the most recently-proposed and still unfulfilled applications for lithium ion devices. Higher energy, power and superior safety standards, well beyond the present state of the art, are actually required to extend the Li-ion battery market to these challenging fields, but such a goal can only be achieved by the development of new materials with improved performances. Focusing on the negative electrode materials, alloying and conversion chemistries have been widely explored in the last decade to circumvent the main weakness of the intercalation processes: the limitation in capacity to one or at most two lithium atoms per host formula unit. Among all of the many proposed conversion chemistries, hydrides have been proposed and investigated since 2008. In lithium cells, these materials undergo a conversion reaction that gives metallic nanoparticles surrounded by an amorphous matrix of LiH. Among all of the reported conversion materials, hydrides have outstanding theoretical properties and have been only marginally explored, thus making this class of materials an interesting playground for both fundamental and applied research. In this review, we illustrate the most relevant results achieved in the frame of the Italian National Research Project FIRB 2010 Futuro in Ricerca “Hydrides as high capacity anodes in lithium cells” and possible future perspectives of research for this class of materials in electrochemical energy storage devices. Full article
(This article belongs to the Special Issue Selected papers from Thematic Meeting “Materials for Energy”)
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Open AccessReview Hydrogen Storage Technologies for Smart Grid Applications
Challenges 2017, 8(1), 13; doi:10.3390/challe8010013
Received: 28 March 2017 / Revised: 17 May 2017 / Accepted: 31 May 2017 / Published: 8 June 2017
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Abstract
The electricity sector is among the main contributors to carbon emissions. This sector has the potential to reduce its carbon emissions through producing electric energy from zero-emitting facilities and optimizing consumption to better accommodate low-carbon emissions. The use of hydrogen combined with smart
[...] Read more.
The electricity sector is among the main contributors to carbon emissions. This sector has the potential to reduce its carbon emissions through producing electric energy from zero-emitting facilities and optimizing consumption to better accommodate low-carbon emissions. The use of hydrogen combined with smart grids, as analyzed in this manuscript, can substantially contribute to climate change mitigation. Full article
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Other

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Open AccessProject Report Ethics and the Potential Conflicts between Astrobiology, Planetary Protection, and Commercial Use of Space
Challenges 2017, 8(1), 12; doi:10.3390/challe8010012
Received: 8 May 2017 / Revised: 24 May 2017 / Accepted: 25 May 2017 / Published: 27 May 2017
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Abstract
A high standard of planetary protection is important for astrobiology, though the risk for contamination can never be zero. It is therefore important to find a balance. If extraterrestrial life has a moral standing in its own right, it will also affect what
[...] Read more.
A high standard of planetary protection is important for astrobiology, though the risk for contamination can never be zero. It is therefore important to find a balance. If extraterrestrial life has a moral standing in its own right, it will also affect what we have to do to protect it. The questions of how far we need to go to protect extraterrestrial life will be even more acute and complicated when the time comes to use habitable worlds for commercial purposes. There will also be conflicts between those who want to set a world aside for more research and those who want to give the green light for development. I believe it is important to be proactive in relation to these issues. The aim of my project is therefore to identify, elucidate, and if possible, suggest solutions to potential conflicts between astrobiology, planetary protection, and commercial use of space. Full article

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