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Hydrogen, Volume 4, Issue 1 (March 2023) – 14 articles

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18 pages, 5536 KiB  
Article
Synergistic Effect of Pd Co-Catalyst and rGO–TiO2 Hybrid Support for Enhanced Photoreforming of Oxygenates
by Imran Majeed, Ayesha Arif, Afifa Idrees, Hafeez Ullah, Hassan Ali, Arshad Mehmood, Ashi Rashid, Muhammad Arif Nadeem and Muhammad Amtiaz Nadeem
Hydrogen 2023, 4(1), 192-209; https://doi.org/10.3390/hydrogen4010014 - 17 Mar 2023
Viewed by 8899
Abstract
Photoreforming biomass-derived waste such as glycerol into hydrogen fuel is a renewable hydrogen generation technology that has the potential to become important due to unavoidable CO2 production during methane steam reforming. Despite tremendous efforts, the challenge of developing highly active photocatalysts at [...] Read more.
Photoreforming biomass-derived waste such as glycerol into hydrogen fuel is a renewable hydrogen generation technology that has the potential to become important due to unavoidable CO2 production during methane steam reforming. Despite tremendous efforts, the challenge of developing highly active photocatalysts at a low cost still remains elusive. Here, we developed a novel photocatalyst with a hybrid support comprising reduced graphene oxide (rGO) and TiO2 nanorods (TNR). rGO in the hybrid support not only performed as an excellent scavenger of electrons from the semiconductor conduction band due to its suitable electrochemical potential, but also acted as an electron transport highway to the metal co-catalyst, which otherwise is not possible by simply increasing metal loading due to the shadowing effect. A series of hybrid supports with different TNR and rGO ratios were prepared by the deposition method. Pd nanoparticles were deposited over hybrid support through the chemical reduction method. Pd/rGO-TNRs photocatalyst containing 4 wt.% rGO contents in the support and 1 wt.% nominal Pd loading demonstrated hydrogen production activity ~41 mmols h−1g−1, which is 4 and 40 times greater than benchmark Au/TiO2 and pristine P25. The findings of this works provide a new strategy in optimizing charge extraction from TiO2, which otherwise has remained impossible due to a fixed tradeoff between metal loading and the detrimental shadowing effect. Full article
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2 pages, 205 KiB  
Editorial
Acknowledgment to the Reviewers of Hydrogen in 2022
by Hydrogen Editorial Office
Hydrogen 2023, 4(1), 190-191; https://doi.org/10.3390/hydrogen4010013 - 15 Mar 2023
Viewed by 988
Abstract
High-quality academic publishing is built on rigorous peer review [...] Full article
16 pages, 6136 KiB  
Article
Distributional Trends in the Generation and End-Use Sector of Low-Carbon Hydrogen Plants
by Nick James and Max Menzies
Hydrogen 2023, 4(1), 174-189; https://doi.org/10.3390/hydrogen4010012 - 2 Mar 2023
Cited by 8 | Viewed by 1836
Abstract
This paper uses established and recently introduced methods from the applied mathematics and statistics literature to study trends in the end-use sector and the capacity of low-carbon hydrogen projects in recent and upcoming decades. First, we examine distributions in plants over time for [...] Read more.
This paper uses established and recently introduced methods from the applied mathematics and statistics literature to study trends in the end-use sector and the capacity of low-carbon hydrogen projects in recent and upcoming decades. First, we examine distributions in plants over time for various end-use sectors and classify them according to metric discrepancy, observing clear similarity across all industry sectors. Next, we compare the distribution of usage sectors between different continents and examine the changes in sector distribution over time. Finally, we judiciously apply several regression models to analyse the association between various predictors and the capacity of global hydrogen projects. Across our experiments, we see a welcome exponential growth in the capacity of zero-carbon hydrogen plants and significant growth of new and planned hydrogen plants in the 2020’s across every sector. Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
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20 pages, 3511 KiB  
Article
Highly Effective Pt-Co/ZSM-5 Catalysts with Low Pt Loading for Preferential CO Oxidation in H2-Rich Mixture
by Marina Shilina, Irina Krotova, Sergey Nikolaev, Sergey Gurevich, Denis Yavsin, Olga Udalova and Tatiana Rostovshchikova
Hydrogen 2023, 4(1), 154-173; https://doi.org/10.3390/hydrogen4010011 - 16 Feb 2023
Cited by 2 | Viewed by 2944
Abstract
New Pt-Co catalysts of hydrogen purification from CO impurities for fuel cells were fabricated via the deposition of monodispersed 1.7 nm Pt nanoparticles using laser electrodispersion on Co-modified ZSM-5 prepared by the Co(CH3COO)2 impregnation. The structure of prepared Pt-Co zeolites [...] Read more.
New Pt-Co catalysts of hydrogen purification from CO impurities for fuel cells were fabricated via the deposition of monodispersed 1.7 nm Pt nanoparticles using laser electrodispersion on Co-modified ZSM-5 prepared by the Co(CH3COO)2 impregnation. The structure of prepared Pt-Co zeolites was studied by low-temperature N2 sorption, TEM, EDX, and XPS methods. The comparative analysis of samples with different Pt (0.01–0.05 wt.%) and Co (2.5–4.5 wt.%) contents on zeolites with the ratio of Si/Al = 15, 28, and 40 was performed in the CO-PROX reaction in H2-rich mixture (1%CO + 1%O2 + 49%H2 + 49%He). The synergistic catalytic action of Pt and Co on zeolite surface makes it possible to completely remove CO from a mixture with hydrogen in a wide temperature range from 50 to 150 °C; the high efficiency of designed composites with low Pt loading is maintained for a long time. The enhancement of PROX performance originates from the formation of new active sites for the CO oxidation at the Pt-Co interfaces within zeolite channels and at the surface. In terms of their activity, stability, and selectivity, such composites are significantly superior to known supported Pt-Co catalysts. Full article
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8 pages, 2125 KiB  
Communication
Modeling of Liquid Hydrogen Tank Cooled with Para-Orthohydrogen Conversion
by Konstantin I. Matveev and Jacob W. Leachman
Hydrogen 2023, 4(1), 146-153; https://doi.org/10.3390/hydrogen4010010 - 8 Feb 2023
Cited by 4 | Viewed by 3053
Abstract
With the accelerating development of liquid-hydrogen storage facilities, the problem of boil-off hydrogen losses becomes very important. A promising method to reduce these losses is to utilize the endothermic para-orthohydrogen conversion of vented hydrogen, which can effectively decrease heat loads on a hydrogen [...] Read more.
With the accelerating development of liquid-hydrogen storage facilities, the problem of boil-off hydrogen losses becomes very important. A promising method to reduce these losses is to utilize the endothermic para-orthohydrogen conversion of vented hydrogen, which can effectively decrease heat loads on a hydrogen tank. To model such a process, a hybrid computational model has been developed, based on the application of computational fluid dynamics for an ullage space, where knowledge of thermal stratification is important, and reduced-order models for other system elements. The simulation results for a spheroidal tank in selected conditions indicated a 10–25% reduction of boil-off losses due to cooling produced by vented hydrogen undergoing para-ortho-conversion. Full article
(This article belongs to the Special Issue Hydrogen Energy Technologies)
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13 pages, 12992 KiB  
Communication
Drone Delivery of Dehydro-Sulfurization Utilizing Doubly-Charged Negative Ions of Nanoscale Catalysts Inspired by the Biomimicry of Bee Species’ Bio-Catalysis of Pollen Conversion to Organic Honey
by Kelvin L. Suggs, Duminda K. Samarakoon and Alfred Z. Msezane
Hydrogen 2023, 4(1), 133-145; https://doi.org/10.3390/hydrogen4010009 - 2 Feb 2023
Viewed by 9467
Abstract
The sulfur dioxide (SO2) compound is a primary environmental pollutant worldwide, whereas elemental sulfur (S) is a global commodity possessing a variety of industrial as well as commercial functions. The chemical relationship between poisonous SO2 and commercially viable elemental S [...] Read more.
The sulfur dioxide (SO2) compound is a primary environmental pollutant worldwide, whereas elemental sulfur (S) is a global commodity possessing a variety of industrial as well as commercial functions. The chemical relationship between poisonous SO2 and commercially viable elemental S has motivated this investigation using the Density Functional Theory calculation of the relative transition state barriers for the two-step dehydro-sulfurization oxidation–reduction reaction. Additionally, doubly-charged nanoscale platelet molybdenum disulfide (MoS2), armchair (6,6) carbon nanotube, 28-atom graphene nanoflake (GR-28), and fullerene C-60 are utilized as catalysts. The optimal heterogeneous and homogeneous catalysis pathways of the two-step oxidation–reduction from SO2 to elemental S are further inspired by the biomimicry of the honeybee species’ multi-step bio-catalysis of pollen conversion to organic honey. Potential applications include environmental depollution, the mining of elemental sulfur, and the functionalization of novel technologies such as the recently patented aerial and amphibious LynchpinTM drones. Full article
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13 pages, 4285 KiB  
Article
Improved Photocatalytic H2 Evolution by Cobaloxime-Tethered Imidazole-Functionalized Periodic Mesoporous Organosilica
by M. Ángeles Navarro, Miguel A. Martín, José Rafael Ruiz, César Jiménez-Sanchidrián, Francisco J. Romero-Salguero and Dolores Esquivel
Hydrogen 2023, 4(1), 120-132; https://doi.org/10.3390/hydrogen4010008 - 2 Feb 2023
Viewed by 2205
Abstract
Molecular cobaloxime-based heterogeneous systems have attracted great interest during the last decades in light-driven hydrogen production. Here, we present a novel cobaloxime-tethered periodic mesoporous organosilica (PMO) hybrid (Im-EtPMO-Co) prepared through the immobilization of a molecular cobaloxime complex on the imidazole groups present in [...] Read more.
Molecular cobaloxime-based heterogeneous systems have attracted great interest during the last decades in light-driven hydrogen production. Here, we present a novel cobaloxime-tethered periodic mesoporous organosilica (PMO) hybrid (Im-EtPMO-Co) prepared through the immobilization of a molecular cobaloxime complex on the imidazole groups present in ethylene-bridged PMO. The successful assembly of a molecular cobaloxime catalyst via cobalt-imidazole axial ligation has been evidenced by several techniques, such as 13C NMR, Raman spectroscopy, ICP-MS, and XPS. The catalytic performance of Im-EtPMO-Co catalyst was essayed on the hydrogen evolution reaction (HER) under visible light in presence of a photosensitizer (Eosin Y) and an electron donor (TEOA). It showed an excellent hydrogen production of 95 mmol hydrogen at 2.5 h, which corresponded to a TON of 138. These results reflect an improved photocatalytic activity with respect to its homogenous counterpart [Co(dmgH)2(Im)Cl] as well as a previous cobaloxime-PMO system with pyridine axial ligation to the cobaloxime complex. Full article
(This article belongs to the Special Issue Catalysts for Hydrogen Generation)
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17 pages, 2085 KiB  
Article
Multi-Model Assessment for Secondary Smelting Decarbonisation: The Role of Hydrogen in the Clean Energy Transition
by Antonis Peppas, Sotiris Kottaridis, Chrysa Politi, Panagiotis M. Angelopoulos and Maria Taxiarchou
Hydrogen 2023, 4(1), 103-119; https://doi.org/10.3390/hydrogen4010007 - 27 Jan 2023
Cited by 2 | Viewed by 2040
Abstract
Extensive decarbonisation efforts result in major changes in energy demand for the extractive industry. In 2021, the extraction and primary processing of metals and minerals accounted for 4.5 Gt of CO2 eq. per year. The aluminium industry was responsible for 1.1 Gt [...] Read more.
Extensive decarbonisation efforts result in major changes in energy demand for the extractive industry. In 2021, the extraction and primary processing of metals and minerals accounted for 4.5 Gt of CO2 eq. per year. The aluminium industry was responsible for 1.1 Gt CO2 eq. direct and indirect emissions. To reach the European milestone of zero emissions by 2050, a reduction of 3% annually is essential. To this end, the industry needs to take a turn towards less impactful production practices, coupling secondary production with green energy sources. The present work aims to comprehensively compare the lifecycle energy consumption and environmental performance of a secondary aluminium smelter employing alternative thermal and electricity sources. In this frame, a comparative analysis of the environmental impact of different thermal energy sources, namely natural gas, light fuel oil, liquified petroleum gas, hydrogen and electricity, for a secondary aluminium smelter is presented. The results show that H2 produced by renewables (green H2) is the most environmentally beneficial option, accounting for −84.156 kg CO2 eq. By producing thermal energy as well as electricity on site, H2 technologies also serve as a decentralized power station for green energy production. These technologies account for a reduction of 118% compared to conventionally used natural gas. The results offer a comprehensive overview to aid decision-makers in comparing environmental impacts caused by different energy sources. Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
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29 pages, 3030 KiB  
Article
The Boundary between Two Modes of Gas Evolution: Oscillatory (H2 and O2) and Conventional Redox (O2 Only), in the Hydrocarbon/H2O2/Cu(II)/CH3CN System
by Igor Yu. Shchapin and Andrey I. Nekhaev
Hydrogen 2023, 4(1), 74-102; https://doi.org/10.3390/hydrogen4010006 - 16 Jan 2023
Viewed by 2067
Abstract
During the oxidation of hydrocarbons using hydrogen peroxide solutions, the evolution of gaseous oxygen is a side and undesirable process, in which the consumption of the oxidizer is not associated with the formation of target products. Therefore, no attention is paid to the [...] Read more.
During the oxidation of hydrocarbons using hydrogen peroxide solutions, the evolution of gaseous oxygen is a side and undesirable process, in which the consumption of the oxidizer is not associated with the formation of target products. Therefore, no attention is paid to the systematic study of the chemical composition of the gas and the mechanisms of its formation. Filling this gap, the authors discovered a number of new, previously unidentified, interesting facts concerning both gas evolution and the oxidation of hydrocarbons. In a 33% H2O2/Cu2Cl4·2DMG/CH3CN system, where DMG is dimethylglyoxime (Butane-2,3-dione dioxime), and is at 50 °C, evidence of significant evolution of gaseous hydrogen, along with the evolution of gaseous oxygen was found. In the authors’ opinion, which requires additional verification, the ratio of gaseous hydrogen and oxygen in the discussed catalytic system can reach up to 1:1. The conditions in which only gaseous oxygen is formed are selected. Using a number of oxidizable hydrocarbons with the first adiabatic ionization potentials (AIPs) of a wide range of values, it was found that the first stage of such a process of evolving only gaseous oxygen was the single electron transfer from hydrogen peroxide molecules to trinuclear copper clusters with the formation, respectively, of hydrogen peroxide radical cations H2O2•+ and radical anions Cu3Cl5•− (AIP = 5 eV). When the conditions for the implementation of such a single electron transfer mechanism are exhausted, the channel of decomposition of hydrogen peroxide molecules into gaseous hydrogen and oxygen is switched on, which is accompanied by the transition of the system to an oscillatory mode of gas evolution. In some cases, the formation of additional amounts of gaseous products is provided by the catalytically activated decomposition of water molecules into hydrogen and oxygen after the complete consumption of hydrogen peroxide molecules in the reaction of gaseous oxygen evolution. The adiabatic electron affinity of various forms of copper molecules involved in chemical processes is calculated by the density functional theory method. Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
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14 pages, 8174 KiB  
Article
µ-CT Investigation of Hydrogen-Induced Cracks and Segregation Effects in Austenitic Stainless Steel
by Gero Egels, Simon Schäffer, Santiago Benito and Sebastian Weber
Hydrogen 2023, 4(1), 60-73; https://doi.org/10.3390/hydrogen4010005 - 13 Jan 2023
Viewed by 9530
Abstract
Hydrogen can drastically degrade the mechanical properties of a variety of metallic materials. The so-called hydrogen environment embrittlement of austenitic CrNi-type steels is usually accompanied by the formation of secondary surface cracks, which can be investigated in order to assess the embrittlement process. [...] Read more.
Hydrogen can drastically degrade the mechanical properties of a variety of metallic materials. The so-called hydrogen environment embrittlement of austenitic CrNi-type steels is usually accompanied by the formation of secondary surface cracks, which can be investigated in order to assess the embrittlement process. The occurrence of hydrogen-induced cracks is often related to element segregation effects that locally impact the austenite stability. Since there is as yet a lack of investigation methods that can visualize both structures three-dimensionally, the present study investigates the imageability of hydrogen-induced cracks and element segregation structures in austenitic CrNi-steel via micro-computed tomography (CT). In order to improve the X-ray visibility of segregation structures, modified versions of the reference steel, X2CrNi18-9, that contain W and Si are designed and investigated. The investigations demonstrated that small differences in the X-ray attenuation, caused by the W or Si modifications, can be detected via CT, although segregation structures could not be imaged due to their small size scale and image noise. Hydrogen-induced cracks were characterized successfully; however, the detection of the smaller cracks is limited by the resolution capability. Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
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18 pages, 2692 KiB  
Article
Comprehensive Thermodynamic Study of Alkyl-Cyclohexanes as Liquid Organic Hydrogen Carriers Motifs
by Sergey P. Verevkin, Artemiy A. Samarov, Sergey V. Vostrikov, Peter Wasserscheid and Karsten Müller
Hydrogen 2023, 4(1), 42-59; https://doi.org/10.3390/hydrogen4010004 - 10 Jan 2023
Cited by 5 | Viewed by 1967
Abstract
Alkyl-cyclohexanes can be considered as suitable model compounds to understand the thermochemistry of aromatic compounds and their hydrogenated counterparts discussed as Liquid Organic Hydrogen Carrier systems. Thermochemical measurements on these hydrogen-rich compounds are thwarted by complications due to the 99.9 % purity limitation [...] Read more.
Alkyl-cyclohexanes can be considered as suitable model compounds to understand the thermochemistry of aromatic compounds and their hydrogenated counterparts discussed as Liquid Organic Hydrogen Carrier systems. Thermochemical measurements on these hydrogen-rich compounds are thwarted by complications due to the 99.9 % purity limitation and sample size specific to these methods. However, the data on vaporisation and formation enthalpies are necessary to optimize the hydrogenation/dehydrogenation processes. In this work, various empirical and theoretical methods are described to reliably assess the gas phase enthalpies of formation and vaporization enthalpies of alkyl-substituted cyclohexanes. The empirical and quantum-chemical methods have been validated against reliable literature data and provide reasonable estimates with an accuracy comparable to that of the experimental data. The liquid phase enthalpies of formation of differently shaped alkyl-cyclohexanes were derived and used to estimate the energetics of their dehydrogenation reactions. The influence of alkyl substituents on the reaction enthalpy is discussed. The vapour pressures of typical hydrogen-rich compounds at technically relevant temperatures were calculated and compared to vapour pressures of biodiesel fuels measured in this work using the static method. Full article
(This article belongs to the Special Issue Feature Papers in Hydrogen (Volume 2))
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20 pages, 3172 KiB  
Article
An Innovative PEMFC Magnetic Field Emulator to Validate the Ability of a Magnetic Field Analyzer to Detect 3D Faults
by Ali Bawab, Stefan Giurgea, Daniel Depernet and Daniel Hissel
Hydrogen 2023, 4(1), 22-41; https://doi.org/10.3390/hydrogen4010003 - 5 Jan 2023
Cited by 4 | Viewed by 1861
Abstract
An original non-invasive methodology of the fuel cell diagnosis is proposed to identify different positions of the faults in Proton Exchange Membrane Fuel Cell (PEMFC) stacks from external magnetic field measurements. The approach is based on computing the external magnetic field difference between [...] Read more.
An original non-invasive methodology of the fuel cell diagnosis is proposed to identify different positions of the faults in Proton Exchange Membrane Fuel Cell (PEMFC) stacks from external magnetic field measurements. The approach is based on computing the external magnetic field difference between normal and faulty PEMFC operating conditions. To evaluate the external magnetic field distribution, in this paper, we propose an improved design of the magnetic field analyzer. This analyzer amplifies the magnetic field around the cell to perform an accurate detection of the fault position. Moreover, the main contribution of this work is represented by conceiving and implementing a 3D multi-physical current distribution emulator of a proton exchange membrane fuel cell. The new concept of a proton exchange membrane fuel cell emulator has been specially designed to emulate the magnetic field of a real fuel cell stack. This emulator concept is also beneficial for a new model of the fuel cell, which implies a multi-physical coupling between electrochemical electric conduction and the generated magnetic field. Finally, finally, the numerical model and the emulator have been involved in the realization of numerical simulations and experimental analysis to prove the ability of the system to detect and localize 3D faults. Full article
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11 pages, 1003 KiB  
Article
Classical Nuclear Motion: Comparison to Approaches with Quantum Mechanical Nuclear Motion
by Irmgard Frank
Hydrogen 2023, 4(1), 11-21; https://doi.org/10.3390/hydrogen4010002 - 29 Dec 2022
Cited by 2 | Viewed by 1507
Abstract
Ab initio molecular dynamics combines a classical description of nuclear motion with a density-functional description of the electronic cloud. This approach nicely describes chemical reactions. A possible conclusion is that a quantum mechanical description of nuclear motion is not needed. Using Occam’s razor, [...] Read more.
Ab initio molecular dynamics combines a classical description of nuclear motion with a density-functional description of the electronic cloud. This approach nicely describes chemical reactions. A possible conclusion is that a quantum mechanical description of nuclear motion is not needed. Using Occam’s razor, this means that, being the simpler approach, classical nuclear motion is preferable. In this paper, it is claimed that nuclear motion is classical, and this hypothesis will be tested in comparison to methods with quantum mechanical nuclear motion. In particular, we apply ab initio molecular dynamics to two photoreactions involving hydrogen. Hydrogen, as the lightest element, is often assumed to show quantum mechanical tunneling. We will see that the classical picture is fully sufficient. The quantum mechanical view leads to phenomena that are difficult to understand, such as the entanglement of nuclear motion. In contrast, it is easy to understand the simple classical picture which assumes that nuclear motion is steady and uniform unless a force is acting. Of course, such a hypothesis must be verified for many systems and phenomena, and this paper is one more step in this direction. Full article
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10 pages, 2358 KiB  
Article
Investigation of Diffusible Hydrogen Concentration in Gas Metal Arc Brazing by Carrier Gas Hot Extraction Method Referring to ISO 3690
by Oliver Brätz, Benjamin Ripsch, Andreas Gericke and Knuth-Michael Henkel
Hydrogen 2023, 4(1), 1-10; https://doi.org/10.3390/hydrogen4010001 - 21 Dec 2022
Viewed by 2118
Abstract
Arc brazing is an alternative joining technology well-suited for processing thermally sensitive materials and to produce mixed material connections. Due to the technological similarities of gas metal arc brazing to gas metal arc welding, it can be assumed that the process-related hydrogen input [...] Read more.
Arc brazing is an alternative joining technology well-suited for processing thermally sensitive materials and to produce mixed material connections. Due to the technological similarities of gas metal arc brazing to gas metal arc welding, it can be assumed that the process-related hydrogen input is of similar magnitude for both joining technologies. Since diffusible hydrogen is known to cause embrittlement in metallic materials, it is necessary to know the amount of diffusible hydrogen introduced by different manufacturing processes. Regarding the qualification of welding procedures, hydrogen ingress is an important factor to evaluate the risk of hydrogen-assisted cold cracking, especially when processing high-strength steels. For arc brazing, there is a lack of knowledge about the process-related hydrogen input. Hence, to study the influence of different brazing filler materials and varying levels of heat input on the diffusible hydrogen concentration in arc braze metal, a methodology to determine hydrogen content in arc weld metal in accordance with international standard ISO 3690 based on carrier gas hot extraction was applied to arc brazed specimens. Very low diffusible hydrogen concentrations of about HD = 0.1 to 0.3 mL/100 g were found for GMAB without significant influence of arc energy or filler metal used. Full article
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