Si Framework Research Articles

Coral-shaped AlSi anode materials for Li-ion batteries enabled by THF-based electrolyte

This research aims to implement a strategy of using a controlled acidic etching on AlSi alloy particles to partially remove Al and preserve a porous Si framework as anode materials. The etched AlSi materials with different Al/Si weight ratios have been investigated in lithium-ion batteries. Microstructural analysis shows the evolution of the AlSi material during selective wet etching, highlighting the preservation of coral-shaped Si nanostructures with an Al-rich core. Lower Al/Si ratios result in increased surface area and pore volume, which is favorable for improving lithium-ion diffusion and accommodating volume expansion during cycling. Evaluation of electrochemical performance in different electrolytes proves the importance of electrolyte selection for AlSi anodes. The tetrahydrofuran-based (THF-based) electrolyte stabilizes electrochemical reactions, resulting in superior specific capacity, cycle life, and Coulombic efficiency compared to the carbonate-based electrolyte with fluoroethylene carbonate additive. Rate performance analysis shows excellent high-rate capability with stable capacity retention at 3C, particularly in Al53Si47 and Al10Si90 materials. Electrochemical impedance spectroscopy measurements emphasize the critical role of porous structure and electrolytes in sustaining low resistance and enhancing cycle life performance. Selective aluminum etching and the THF-based electrolyte effectively mitigate the breakdown and subsequent reformation of the solid electrolyte interphase, resulting in superior efficiency and extended lifespan.

Selecting sustainability indicators for smart product design based on industry 4.0/5.0 technologies: analysis and proposal of a methodological framework

AbstractIndustry 4.0 deals with a digital revolution, integrating technologies like Virtual Reality, Augmented Reality, Digital Twin, and Robotics. This transformation unlocks opportunities in engineering, addressing sustainability challenges. Stakeholders use I4.0 technologies, including Industry 5.0, to measure sustainability indicators. This paper reviews I4.0 technologies for assessing sustainability, offering an SI framework in manufacturing and smart product design. Decision-makers can optimize environmental, social, and economic impacts in smart product design using this framework.

Ladderlike polysilsesquioxanes derived dual-carbon-buffer-shell structural silicon as stable anode materials for lithium-ion batteries

Silicon-carbon (Si/C) composite materials have been proven to be one of the most promising anode materials for the next generation of lithium-ion batteries (LIBs) due to their high theoretical capacity. However, the substantial volume changes during alloying/dealloying processes have posed significant challenges to the working lifespan of Si-based anodes. In this study, we designed a dual-carbon-layer-structured Si composite anode material (DCS-Si). Using ladderlike polysilsesquioxanes as a precursor, we employed a zinc thermal reaction to internally reduce the Si–O–Si framework to Si0. Simultaneously, the phenyl groups directly connected to Si atoms served as a carbon source for the internally dense coating layer. The obtained product underwent further coating controllable pyrolysis reactions to form an external carbon coating layer. As anode for LIBs, DCS-Si delivered a reversible specific capacity exceeding 1000 mAh g−1. Even after 1350 cycles at a current density of 0.3 A g−1, the specific capacity remained above 500 mAh g−1. Moreover, even under a high current density of 3 A g−1, after nearly 1000 cycles, the capacity retention rate still exceeded 70%. Further testing of the full cell also indicated that DCS-Si is a highly promising high-energy-density anode, with potential applications in future commercial lithium-ion batteries.

Impact of H2O on CO2 adsorption and co-adsorption: Mechanism and high-performance adsorbents for efficient H2O-CO2 capture

Physical adsorbents used for CO2 capture from air directly and wet CO2 flue gas have limited effectiveness due to competitive adsorption of H2O and CO2. Therefore, it is crucial to understand the impact of H2O on CO2 adsorption and investigate the co-adsorption mechanism in order to enhance the screening, design, and optimization of carbon capture systems. Herein, heat treatments are performed on commercial NaX zeolites to modify the composition of the O-T-O (T = Al, Si) framework. Our systematic investigation based on thermogravimetric analysis/differential scanning calorimetry (TG-DSC), infrared spectroscopy (IR), solid-state nuclear magnetic resonance (SSNMR), and density-functional theory (DFT) calculation, the connection between the structure of NaX zeolite and H2O and CO2 adsorption/desorption is established. The heat-induced changes in the O-T-O (T = Al, Si) framework produce movements of the loaded Na+ ions. Hydrogen bonds formed by agglomerated adsorbed H2O constitute the primary source of desorption heat, which adversely affects CO2 mass transfer and adsorption. Our findings illustrate that modifying the distribution of Na+ ions in the O-T-O (T = Al, Si) framework can reduce the CO2 adsorption energy and prevent the formation of water agglomerates. Our findings provide insights into the design of efficient and high-capacity adsorbents for CO2 capture that can be operated in the presence of H2O.

Clarifying the effects of nanoscale porosity of silicon on the bandgap and alignment: a combined molecular dynamics-density functional tight binding computational study.

Porous silicon (pSi) has been studied for its applications in solar cells, in particular in silicon-silicon tandem solar cells. It is commonly believed that porosity leads to an expansion of the bandgap due to nano-confinement. Direct confirmation of this proposition has been elusive, as experimental band edge quantification is subject to uncertainties and effects of impurities, while electronic structure calculations on relevant length scales are still outstanding. Passivation of pSi is another factor affecting the band structure. We present a combined force field-density functional tight binding study of the effects of porosity of silicon on its band structure. We thus perform electron structure-level calculations for the first time on length scales (several nm) that are relevant to real pSi, and consider multiple nanoscale geometries (pores, pillars, and craters) with key geometrical features and sizes of real porous Si. We consider the presence of a bulk-like base with a nanostructured top layer. We show that the bandgap expansion is not correlated with the pore size but with the size of the Si framework. Significant band expansion would require features of silicon (as opposed to pore sizes) to be as small as 1 nm, while the nanosizing of pores does not induce gap expansion. We observe a graded junction-like behavior of the band gap as a function of Si feature sizes as one moves from the bulk-like base to the nanoporous top layer.

Defining relative humidity in terms of water activity: III. Relations to dew-point and frost-point temperatures

Relative humidity (RH) is a fundamental quantity used in many fields of engineering and science, and in particular in meteorology and climate research. Relative fugacity (RF) and, equivalently, relative activity of water vapour in humid air have recently been proposed as a physically well-founded, unambiguous common metrological reference quantity for several conventional but mutually inconsistent definitions of RH. The RF definition is valid is valid under real-gas conditions and above boiling and sublimation temperatures. While differences between RH and RF mostly remain within uncertainties of typical present-day RH measurements, such systematic discrepancies are expected to be of substantial climatological relevance. Consequently, interdisciplinary harmonisation of RH definitions is overdue within the SI framework. Dew-point and frost-point temperatures are preferred measurands in humidity metrology using, for example, chilled-mirror hygrometers. Here, relations are presented for estimating RF from those temperatures, based on equations of state of the 2011 IUGG 5IUGG: International Union of Geodesy and Geophysics, https://iugg.org/. standard TEOS-10, the ‘international thermodynamic equation of seawater—2010’. Recommendations are given for numerically computing RF using the open-source TEOS-10 SIA library 6 6SIA Library: Sea-Ice-Air Library of TEOS-10, http://teos-10.org.. The asymptotic limiting laws of RF for nearly saturated humid air exhibit the familiar form of Clausius–Clapeyron-like equations, despite departing from ideal-gas assumptions. Under various practical conditions, these simple equations may cover the full humidity range with only minor residuals compared to the full numerical TEOS-10 solution for RF.

Thermal and mechanical properties of the clathrate-II Na24Si136

Thermal expansion, lattice dynamics, heat capacity, compressibility, and pressure stability of the intermetallic clathrate ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$ have been investigated by a combination of first-principles calculations and experimentation. Direct comparison of the properties of ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$ with those of the low-density elemental modification ${\mathrm{Si}}_{136}$ provide insight into the effects of filling the silicon clathrate framework cages with Na on these properties. Calculations of the phonon dispersion only yield sensible results if the Na atoms in the large cages of the structure are displaced from the cage centers, but the exact nature of off-centering is difficult to elucidate conclusively. Pronounced peaks in the calculated phonon density of states for ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$, absent for ${\mathrm{Si}}_{136}$, reflect the presence of low-energy vibrational modes associated with the guest atoms, in agreement with prior inelastic neutron-scattering experiments and reflected in marked temperature dependence of the guest atom atomic displacement parameters determined by single-crystal x-ray diffraction. The bulk modulus is only weakly influenced by filling the Si framework cages with Na, whereas the phase stability under pressure is significantly enhanced. The room-temperature linear coefficient of thermal expansion (CTE) is nearly a factor of 3 greater for ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$ compared to ${\mathrm{Si}}_{136}$. Negative thermal expansion (NTE), observed in ${\mathrm{Si}}_{136}$ below 100 K, is noticeably absent in ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$. In contrast to ${\mathrm{Si}}_{136}$, the thermal expansion behavior in ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$ is relatively well described by the conventional Gr\"uneisen-Debye model in the temperature range of 10--700 K. First-principles calculations in the quasiharmonic approximation correctly predict an increase in high-temperature CTE with Na loading, although the increase is less than observed in experiment. The calculations also fail to capture the absence of NTE in ${\mathrm{Na}}_{24}{\mathrm{Si}}_{136}$, perhaps due to anharmonic effects and/or inadequateness of the ordered structural model.

Acidity and Stability of Brønsted Acid Sites in Green Clinoptilolite Catalysts and Catalytic Performance in the Etherification of Glycerol

Natural zeolite clinoptilolite CLIN with a framework ratio of Si/Al ≥ 4 containing mainly potassium and calcium ions in its internal channel system was used as a starting material. The acidic HCLIN catalysts were prepared under soft conditions avoiding the use of environmental less-benign mineral acids. The starting material was ion exchanged using a 0.2 M aqueous ammonium nitrate solution at a temperature 80 °C for 2 h. The obtained NH4CLIN was converted into the acid HCLIN catalyst by calcination at 300–600 °C. The obtained samples were characterized by XRD, FTIR, SEM/TEM, AAS, and EDX element mapping. The state of aluminium and silicon was studied by 27Al- and 29SiMAS NMR spectroscopy. The textural properties of the catalysts were investigated by nitrogen adsorption and desorption measurements. The Brønsted acidity of the HCLIN catalysts was studied by temperature-programmed decomposition of the exchanged ammonium ions releasing ammonia as well as 1H MAS NMR, {1H–27Al} Trapdor, and {1H–27Al} Redor experiments. The strongly agglomerated samples were crystalline and thermally stable up to >500 °C. Although a part of the clinoptilolite framework is maintained up to 600 °C, a loss of crystallinity is already observed starting from 450 °C. The specific surface areas of the starting CLIN and ammonium exchanged NH4CLIN are low with ca. 26 m2/g. The pores are nearly blocked by the exchangeable cations located in the zeolite pores. The thermal decomposition of the ammonium ions by calcination at 400 °C causes an opening of the pore entrances and a markable increase in the specific micropore area and micropore volume to ca. 163 m2/g and 0.07 cm3/g, respectively. It decreases with further rising calcination temperature indicating some structural loss. The catalysts show a broad distribution of Brønsted acid sites (BS) ranging from weak to strong sites as indicated the thermal decomposition of exchanged ammonium ions (TPDA). The ammonium ion decomposition leaving BS, i.e., H+ located at Al–O–Si framework bridges, starts at ≥250 °C. A part of the Brønsted sites is lost after calcination specifically at 500 °C. It is related to the formation of penta-coordinated aluminium at the expense of tetrahedral framework aluminium. The Brønsted sites are partially recreated after repeated ammonium ion exchange. The catalytic performance of the acidic HCLIN catalysts was tested in the etherification of glycerol as a green renewable resource with different C1-C4 alcohols. The catalysts are highly active in the etherification of glycerol, especially with alcohols containing the branched, tertiary alkyl groups. Highest activity is observed with the soft activated catalyst HCLIN300 (300 °C, temperature holding time: 1 min). A total of 78% conversion of glycerol to mono and di ether were achieved with tert-butanol at 140 °C after 4 h of reaction. The mono- and di-ether selectivity were 75% and 25%, respectively. The catalyst can be reused.

Introducing Collaborative Governance in Decentralized Land Administration and Management in South Africa: District Land Reform Committees Viewed through a ‘System of Innovation’ Lens

A Fit-for-Purpose (FFP) land administration system strives for a more flexible, inclusive, participatory, affordable, reliable, realistic, and scalable approach to land administration and management in developing countries. The FFP finds itself thus at the interface with the coordination and governance challenges of the mainstream promotion of democratic decentralization of the past decades in general, and collaborative systems for decentralized and participatory land governance in Africa, in particular. One recent example of such collaborative systems for decentralized land governance is the introduction in South Africa between 2015 and 2019 of District Land Reform Committees (DLRCs). We analyze this official experiment in collaborative land governance from a ‘system of innovation’ (SI) perspective. An adapted SI framework is developed and applied in three DLRCs. This study points out that for the innovation of collaboration to be effective, DLRCs require a firm operational and institutional backup. This is an important lead for the general discussion on inclusion, participation, and collaboration in FFP. We not only need these innovations to be well-supported and -resourced; they also require the explicit adoption of a systemic perspective in which various technical and social dimensions are interlinked.

Controlling the Sorption Activity of Clinoptilolites with Mechanical Activation

We have studied the effect of the phase composition of clinoptilolite rocks and the specific mechanical energy delivered to samples in a vibratory attritor on their physical properties and oil sorption capacity. Mechanical activation in air has been shown to cause amorphization, transformation of “zeolitic” water into “hydroxyl” water, and an electron density redistribution in the Al–O–Si framework of the clinoptilolite. Milling to a specific mechanical energy of 2.16 kJ/g leads to the formation of molecularly dense aggregates, which shows up as a decrease in specific surface area, demonstrated by BET measurements. An optimal approach for raising oil sorption capacity is mechanical activation of clinoptilolite–stilbite rock in air to a specific mechanical energy of 5.04 kJ/g.

Boosting the Dynamic Range for Electrochemical Sensing of Hydrogen Peroxide by Enhanced Integration of Pd Nanoparticles in 3D Porous Si Framework

AbstractThree‐dimensional porous silicon framework (3D‐pSi) integrated with various nanostructures is highly potential for functional devices usage such as micro fuel cells or sensing chips. For noble metal deposition in highly directional Si nanowire array or porous Si with large aspect ratios, one difficulty is the restriction on the depth of deposition available. Herein, we would like to introduce a facile route to enhance the integration of Pd nanoparticles with anisotropic Si porous structure. By converting Si nanowire array into 3D‐pSi, the surface coverage of Pd nanoparticles is effectively improved as shown by scanning electron micrographs and cross‐sectional element mapping data. The relative electrochemical active surface area is increased by 3.5 folds. In order to demonstrate the merits brought by this morphological evolution, the electrochemical sensing devices are prepared for detecting H2O2 in PBS solution. As shown by differential pulse voltammetry, the upper limit of linear range of detection can be raised from 6.30 mM to 14.95 mM. This approach may indicate an alternative for boosting the performance of future sensing chips with progressively limited die area, especially attractive for those scenarios where large dynamic range is favourable.

Mesopore-selective incorporation of strong Brønsted acid catalytic sites via aluminium grafting on hierarchically porous siliceous MFI zeolite

Abstract Post-synthetic Al grafting onto the surface silanols in mesoporous MFI zeolite has been investigated in an attempt to obtain a model catalytic material that possesses strong Bronsted acid sites at mesopore surfaces of the zeolite, but not inside the microporous framework. To this end, a siliceous MFI zeolite with a mesopore/micropore hierarchy was synthesized using a meso-micro dual structure-directing diammonium surfactant. The hierarchically porous zeolite was treated with anhydrous AlCl3 for the formation of Si–O–Al bonding with silanols on the mesopore surfaces. According to solid-state 31P NMR spectroscopy of the surface-adsorbed phosphine oxides and catalytic activity for decalin cracking, the Al-grafting treatment performed in the conventional manner resulted in the formation of weak Bronsted acid sites, similar to Al grafting on SBA-15 mesoporous silica. To obtain strong Bronsted acid sites, we have developed a method of heating the AlCl3-grafted zeolite in a controlled-humidity chamber before calcination. The resultant zeolite was catalytically active for cracking of hydrocarbons requiring strong acid sites, but not for methanol-to-hydrocarbon conversion. The results support that the moisture treatment caused a local reconstruction of the initially grafted Al–O–Si framework portion to a strong Bronsted acid site. In addition, our model catalytic zeolite material unveiled the catalytic activity of Bronsted acid sites at the mesopore surfaces in hierarchically porous zeolite in n-octane cracking. Furthermore, we confirmed that this method was effective for other mesoporous MFI zeolites obtained through a post-synthetic desilication route.

Acid Leaching of Desilication Products: Implications for Acid Neutralization of Bauxite Residue

Acid (inorganic or organic) neutralization of bauxite residue has been one of the main approaches to reduce its alkalinity, which is largely caused by desilication products (DSP). However, the acid leaching mechanisms remain unsolved as they are complicated by complex mineralogy and different test conditions used in previous studies. In this study, bauxite residue and two DSP phases, zeolite Linde Type A (LTA) and sodalite, were leached using aqueous HCl solutions with concentrations ranging from 0 to 1 M. The leaching kinetics of Na, Al, and Si were measured, and solid samples were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM) cross-section elemental mapping. The results reveal that DSP neutralization occurs in two stages: Na+–H+ ion exchange and hydrolysis of the Al–O–Si framework (dissolution of DSP). In the ion exchange stage, minimal Al and Si react compared with Na that readily dissolves. During the hydrolysis stage, reacted zeolite LTA converts to an amorphous phase while the sodalite aluminosilicate framework is dissolved.

The dielectric relaxation behavior induced by sodium migration in the Na2CoSiO4 structure within a three-dimensional Co-O-Si framework.

The disodium cobalt(ii) orthosilicate material (NCS) has been synthesized using improved solid-state (NCS-SS) and co-precipitation (NCS-CP) methods of synthesis. The Rietveld refinement of the XRD pattern of Na2CoSiO4 has demonstrated an orthorhombic crystal system with the space groups Pna21 and Pbca for NCS-SS and NCS-CP respectively. The elemental mapping of microstructures by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) showed the porous morphology and the homogenous particles of the Na2CoSiO4 powders. Their dielectric properties were measured in the frequency and temperature ranges of 0.1–106 Hz and 383–613 K respectively. Different dielectric relaxation phenomena associated with the Na+-ion migration through different paths were displayed in relation with the temperature and frequency. The decrease and increase in the dielectric properties were found to be dependent on the formation of short-range ordered structure formed after the migration of Na+-ions. In the present work, an attempt has been made to study the relation between the structural properties and the dielectric process. Thus, interesting insights into the transport behavior of Na+-ions in different chemical environments were obtained. This in turn provides an effective procedure to probe the relationship between the diffusion pathway of Na+-ions and the dielectric response.

Structural and electronic properties of nanosize semiconductor CeSin0/− (n = 4–20) material: A double-hybrid density functional theory investigation

Structural evolution model, HOMO-LUMO gap, relative stability, magnetic moment and spectral property of nanosize CeSin0/− (n = 4–20) semiconductor material were performed by employing double-hybrid density functional scheme. Optimized geometries for CeSin displayed that the most stable structure is Ce-substituted for a Si in the ground state of Sin+1 with n ≤ 17; Ce atom as linker connects two small silicon subclusters with n = 17–19; and Ce atom is encapsulated into cage-like Si framework with ≥20. For anion, the most stable structure of CeSin− is Ce-linked configuration with n = 8–18 excluded n = 9, and Ce atom is encapsulated into cage-like motif with n = 19–20. The spectral information was reported. The 4f electron of Ce atom in CeSin0/− does not participate in bonding, resulting the total magnetic moments of neutral and anionic CeSin0/− clusters are 2 and 1 μB, respectively. HOMO-LUMO gap, relative stability and chemical bonding analyses revealed that encapsulated configuration of CeSi20− is a “magic” cluster.

Development of a Sustainability Index for an Energy Management System in Thailand

The ISO 50001 energy management system (EnMS) standard was published in June 2011 and has been widely adopted by organizations from around the world, including Thailand. From 2014–2017, there was a continuous increase in the number of ISO 50001-certified companies in the East Asia and Pacific regions and, more broadly, the world, although this is not consistent with the number of companies that emerged during this period in Thailand. This information shows that the implementation of energy management in some companies may not be sustainable. This research offers a novel method for assessing the quality of energy management in the form of an energy management system sustainability index (EnMS SI) framework, presenting the economic, organizational, energy performance, and environmental aspects of sustainable energy management. Data collection, from a literature review of related research and the EnMS good practices, was implemented in order to select sustainability indicators and further develop a sustainability index for energy management. The analytic hierarchy process (AHP) and weighted arithmetic mean (WAM) were used to establish an EnMS SI. The study results were then assessed and validated using 31 ISO 50001-certified companies in Thailand. Direct interviews and questionnaires were used to obtain responses from energy management representatives. The studied data indicated that an EnMS SI framework can be used in qualitative analyses to effectively determine the sustainability of an EnMS. Significant sustainability indicators, consisting of continuous benefits, top management commitment, and long-term strategic planning, were found. The results also revealed that the EnMS in Thailand has been significantly economically weak. The EnMS SI framework is a tool for assessing energy management sustainability, which allows for the determination of an organization’s actual strengths and weaknesses. The benefits of this framework include the possibility of determining guidelines for correcting and improving the EnMS to achieve sustainability.

Controlling acidity and external surface morphology of SAPO-34 and its improved performance for methanol to olefins reaction

Abstract Hollow SAPO-34 with thin-wall were successfully synthesized by mixed templates and varying the silicon content in the gel. The silicon enrichment at the surface of crystals occurs on both low silicon and high silicon samples. The cubic crystals of the molecular sieve transformed from hollow to dense phase with increase of silicon content. The surface of molecular sieve crystals turned from being abundant of macroporous openings to be integrated without visible macroporous cracks with the increase of silicon content in the gel. The thin-wall SAPO-34 with low acid density and Si(4Al) framework structure, synthesized from the low silicon content (nSiO2/nAl2O3 = 0.1) of the gel, presented the highest ethylene plus propylene selectivity. The hollow structure SAPO-34 with medium acid density obtained with medium silicon content (nSiO2/nAl2O3 = 0.26) in the gel possessed the longest lifetime.

Porous Si/C microspheres decorated with stable outer carbon interphase and inner interpenetrated Si@C channels for enhanced lithium storage

The dual-functional carbons are decorated on porous Si microspheres with interpenetrated Si@C channel and stable outer carbon interphase, which are employed to boost the lithium storage and remedy the vital shortcomings of the Si anode, in terms of unstable solid−electrolyte interphase layer, terrible electronic conductivity, huge volume changes as well as bad cycling or rate capability. In this designed composite, the outer carbon layer can perfectly maintain the structure stability and avoid direct contact of Si with electrolyte during cycling, thus resulting in stable solid−electrolyte interphase film and improved initial coulombic efficiency. Furthermore, the inner carbon layer coated directly onto the porous Si framework can effectively enhance the overall conductivity, let the lithium insert fully and endow the composite with higher capacity in half and full cell. As a result, the as-prepared porous Si/C microspheres deliver a reversible capacity of 1660 mAh g−1 at 0.2 A g−1 after 100 cycles and 826.8 mAh g−1 at 2 A g−1 after 200 cycles.

Global analysis of multi-host and multi-vector epidemic models

We formulate a multi-group and multi-vector epidemic model in which hosts' dynamics is captured by staged-progression SEIR framework and the dynamics of vectors is captured by an SI framework. The proposed model describes the evolution of a class of zoonotic infections where the pathogen is shared by m host species and transmitted by p arthropod vector species. In each host, the infectious period is structured into n stages with a corresponding infectiousness parameter to each vector species. We determine the basic reproduction number R02(m,n,p) and investigate the dynamics of the systems when this threshold is less or greater than one. We show that the dynamics of the multi-host, multi-stage, and multi-vector system is completely determined by the basic reproduction number and the structure of the host-vector network configuration. Particularly, we prove that the disease-free equilibrium is globally asymptotically stable (GAS) whenever R02(m,n,p)<1, and a unique strongly endemic equilibrium exists and is GAS if R02(m,n,p)>1 and the host-vector configuration is irreducible. That is, either the disease dies out or persists in all hosts and all vector species.

Hydrogen Storage, Magnetism and Electrochromism of Silver Doped FAU Zeolite: First-Principles Calculations and Molecular Simulations.

The complex configuration, H2 adsorption binding energy, magnetic, and optical properties of FAU zeolites with Ag cations loaded by ion exchange in the vacant dielectric cavities were investigated by employing the first-principles calculations with all-electron-relativistic numerical atom-orbitals scheme and the Metropolis Monte Carlo molecular simulations. The visible absorption spectrum peaked at distinct wavelengths arranging from red or green to blue colors when changing the net charge load, due to the produced various redox states of Ag cations exchanging at multiple Li+-substituted sites. The spin population analyses indicate the ferrimagnetic coupling between Al–O–Si framework and Ag cations originates from the major ferromagnetic spin polarization in Ag cation cluster coordinating with sodalite cages, with the net spins appreciably depending on the Ag content and exchange site. The H2 adsorption capacities and binding energies represent significant dependence on the content, location, and electronic property of Ag cations introduced into the FAU zeolites. The evident decrease of H2 adsorption binding energy with increased loading concentration demonstrates repulsive interaction between H2 molecules and heterogeneous adsorption configuration on Ag cations. The adsorption sites of H2 sorted by the binding energy with different adsorption configurations were correlated with exchange sites of Ag cations under different Ag loading to comprehend the H2 adsorption mechanism.