Structure Of Salt Research Articles

Breaking Symmetry for SHG Response: Lanthanide Acetate Crystals via Water Molecule Regulation Strategy.

In the field of nonlinear optical (NLO) materials research, the design and synthesis of novel materials are crucial for advancing modern scientific and technological development. This study employs an innovative coordination strategy, building upon the existing structure of [Ln2(CH3COO)6(H2O)4]·4H2O (Ln = Tb, Sm), to successfully synthesize a series of acetate rare-earth metal compounds [Ln2(CH3COO)6(H2O)]n [Ln = Tb(1), Er(2), Y(3)] by regulating the number of water molecules. This approach achieved a structural transition from centrosymmetric (CS) to noncentrosymmetric (NCS), endowing these compounds with significant nonlinear optical responses. We discovered that reducing the coordinated water molecules and introducing acetate as a bidentate ligand is an effective method for modulating crystal structure and realizing NLO performance. This finding not only deepens the understanding of the structure of acetate salts but also provides important theoretical and experimental support for the development of materials with potential NLO propeties.

Structural evolution of the Handun salt diapir, Zagros fold and thrust belt, southern Iran

The Fars region, in the Zagros fold and thrust belt, hosts a wide range of diapirs piercing over 10 km of stratigraphic sequence. Comprising Precambrian to Early-Cambrian Hormuz Salt, these diapirs exhibit a prolonged history of evolution. Outcrop evidence for understanding the diapir deformation history is mostly limited to the Cenozoic contractive phase, and the seismic data lacks the necessary quality for an exhaustive understanding of the deepest structure's geometries. Through regional and field evidence we unravel the Handun salt structure evolution and propose a sequential restoration to describe the key deformational events. Our study presents a field-based novel regional balanced cross-section and a 3D-geological model, and addresses the role of structural inheritances and the position of the Handun diapir with respect to the decupled basement. The performed field studies describe folds and unconformities related to Cenozoic halokinetic sequences with exceptional clarity. It was possible to observe changes of the diapir activity along the structure and provide field evidence for the relative timing and kinematics of primary and secondary welding. Finally, our data suggest that the Handun diapir formed in the early Paleozoic above the shoulder of a basement extensional fault, and was partially translated above its southern hanging-wall during the shortening. In the Paleocene a sustained ratio of salt rise rate was enhanced by the Zagros/Oman contraction. In response to the Oligocene continental collision, the diapir was profusely supplied with salt, which flared upward to form overhangs. Since the middle Miocene the salt supply slowly depleted, with the diapiric walls remaining near the surface but tapering upward, probably due to primary welding or increased sedimentation. Secondary welding occurred post-Pliocene in the last stages of the diapir evolution with consequent development of a secondary minibasin.

Thermal energy storage behaviour of 3D ceramic/molten salt structures under real concentrated solar radiation

Molten salts, phase change materials commonly employed in thermal energy storage (TES) systems, are widely known to enhance the efficient use and storage of solar energy in concentrated solar power (CSP) plants. Here, three-dimensional TES (3DTES) have been manufactured from highly porous (up to ∼90 %) 3D printed patterned vermiculite (V) and alumina (Al2O3) supports, which have been infiltrated with molten sodium nitrate salt (nn) and solar salt (ss). These 3DTES have been validated under real concentrated solar radiation in a parabolic solar furnace. Among the different 3DTES, those based on V-nn exhibits the best efficiency for the conversion of the incident solar radiation into heat; whereas Al2O3-nn transfers the heat more efficiently and allows a faster charging-discharging cyclability due to its higher thermal conductivity. This study confirms the benefits of additive manufacturing to develop a new class of innovative TES for CSP applications.

Synthesis, pharmacological evaluation, and modeling of novel quaternary ammonium salts derived from β-carboline containing an imidazole moiety as angiogenesis inhibitors

In this study, a series of novel β-carboline condensed imidazolium derivatives (7a-7y) were designed and synthesized by incorporating imidazolium salt structures into β-carboline. The cytotoxicity of compounds 7a-7y was evaluated in various cancer cell lines, including lung cancer (A549), gastric cancer (BGC-823), mouse colon cancer (CT-26), liver cancer (Bel-7402), and breast cancer (MCF-7), using the MTT assay. Most compounds exhibited significant activity against one or more of the cancer cell lines. Notably, compounds 7 g, 7o, 7r, 7 s, 7u, 7v, 7x, and 7w showed the highest cytotoxic activity (IC50 < 2 μM) in the tested tumor cell lines. Compound 7x demonstrated cytotoxic activities of 1.3 ± 0.3 μM (for BGC-823), 2.4 ± 0.4 μM (against A549), 7.8 ± 0.9 μM (for Bel-7402), and 9.8 ± 1.4 μM (against CT-26). The chick chorioallantoic membrane assay revealed significant anti-angiogenic potential of compound 7x. Molecular imprinting studies suggested the anti-angiogenic effect of compound 7x might be attributed to inhibition of VEGFR2 kinase. Molecular docking and molecular dynamics further indicate that its activity may be primarily associated with the potential inhibition of VEGFR2. Our research outcomes have provided valuable lead compounds for the development of novel antitumor drugs and have offered beneficial insights for subsequent drug design and optimization.

Potential Field Imaging of Salt and Basement Structures in the Southern Zagros Foreland Basin

Potential Field Imaging of Salt and Basement Structures in the Southern Zagros Foreland Basin

Local structure maturation in high entropy oxide (Mg,Co,Ni,Cu,Zn)1‐x(Cr,Mn)xO thin films

AbstractHigh entropy oxides (HEOs) have garnered much interest due to their available high degree of tunability. Here, we study the local structure of (MgNiCuCoZn)0.167(MnCr)0.083O, a composition based on the parent HEO (MgNiCuCoZn)0.2O. We synthesized a series of thin films via pulsed laser deposition at incremental oxygen partial pressures. X‐ray diffraction shows lattice parameters to decrease with increased pO2 pressures until the onset of phase separation. X‐ray absorption fine structure shows that specific atomic species in the composition dictate the global structure of the material as Cr, Co, and Mn shift to energetically favorable coordination with increasing pressure. Transmission electron microscopy analysis on a lower‐pressure sample exhibits a rock salt structure, but the higher‐pressure sample reveals reflections reminiscent of the spinel structure. In all, these findings give a more complete picture of how (MgNiCuCoZn)0.167(MnCr)0.083O forms with varying initial conditions and advances fundamental knowledge of cation behavior in high entropy oxides.

Hydrogen-bonding interactions in the salts 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, 2,4,6-triaminopyrimidin-1-ium N-phenylantharanilate and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate.

Three salts, namely, 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, C4H8N5+·C6H7O2-·2H2O, (I), 2,4,6-triaminopyrimidin-1-ium N-phenylanthranilate, C4H8N5+·C13H10NO2-, (II), and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate, C4H8N5+·C7H7O3S-, (III), were synthesized, characterized by X-ray diffraction techniques and their supramolecular interactions investigated. In all three crystal structures, protonation of the pyrimidine moiety occurs at the N1 position and is reflected in a widening of the C-N-C bond angle. In salts (I)-(III), the primary acid-base interaction occurs through a pair of N-H...O hydrogen bonds to give a heterodimeric R22(8) synthon. Salts (II) and (III) form a discrete centrosymmetric base pair that produces a homodimeric R22(8) synthon and salt (I) forms a water-mediated base pair resulting in a tetrameric R44(12) synthon. The supramolecular patterns exhibited by sulfonate salt (III) mimic the patterns of carboxylate salt (II) and both exhibit a DADA array (D = donor and A = acceptor) quadruple hydrogen-bonded pattern. The crystal structures of salts (I) and (III) are stabilized by offset and face-to-face aromatic π-π stacking interactions, respectively. The resulting architectures in salts (I)-(III) are a supramolecular sheet with a rosette-like architecture in (I), a supramolecular sheet-like architecture in (II) and a three-dimensional supramolecular network in (III).

Achieving high efficiency and bandwidth enhancement of DRA arrays: Synergic effects of LiMg4AlO6 microwave dielectric ceramic and 2D metamaterials

In this paper, LiMg4AlO6 ceramics with a sintering temperature of 1380 °C to 1460 °C are prepared, and the microwave dielectric properties of the ceramics and their potential application in dielectric resonator antenna (DRA) arrays are investigated. Analysis techniques such as XRD and Rietveld refinement reveal that the LiMg4AlO6 ceramics are rock salt structures and the space group is Fm-3 m (225). The ceramic obtained excellent microwave dielectric properties (εr = 10.17, Q×f = 172, 558 GHz, and τf = - 32.5 ppm/ °C) at 1440 °C. The εr of LiMg4AlO6 ceramics exhibits minimal variation across a wide temperature range (-100 °C to 400 °C) without phase transition. Furthermore, the 2D metamaterials (metasurfaces) are introduced in the DRA, which can significantly improve the radiation efficiency and bandwidth of the antenna. Measured results demonstrate that the antenna has a wide bandwidth ranging from 8.07 GHz to 8.57 GHz, with a maximum realized gain of 8.9 dBi and a peak radiation efficiency of 97%. The proposed ceramic antenna array combines the superior properties of 2D metamaterials and ceramic materials, which opens up a new avenue for ceramic antenna design and satellite communication applications.

Microscopic mechanism of oxygen consumption inhibitor delaying the oxidation of coal

In order to inhibit the coal-oxygen complex that triggers spontaneous coal combustion, a retardant consisting of sodium alginate solution, sodium bicarbonate, inorganic salt MgCl2 and deoxidiser that can achieve multiple effects of hysteresis and oxygen depletion was developed. Taking the sulfur-containing side-chain reactive group of coal molecule -CH2-SH as the object of study, the Gaussian 16W procedure and density-functional-transfer theory (DFT) were applied to investigate the electrostatic potential and reaction tendency, oxygen adsorption capacity, front-line orbitals, natural bonding capacity, and oxygen adsorption capacity of the reactive group before and after the formation of the complexes with Na+ and Mg2+, using the solvation effect at the level of B3LYP/6-31G(d, p), respectively. The changes of electrostatic potential and reaction tendency, oxygen adsorption, front orbitals, natural bonding orbitals and charge transfer before and after the formation of complexes between -CH2-SH reactive groups and Na+, Mg2+, respectively. Comparative analysis of the interaction with oxygen before and after the formation of coordination blocking structure of coal and inorganic salts in gaseous environment, aqueous environment and retarded oxygen-depleting sodium alginate blocking solution environment, respectively. The calculated results show that the side chain of the aromatic ring of the raw coal is the active site for easy adsorption of oxygen, and the stability of the coordination blocking structure is significantly enhanced under the environment of hysteretic oxygen-depleting sodium alginate gel blocking agent, and the adsorption of oxygen before and after the coal molecule combines with Na+ and Mg2+ is the weakest under the environment of hysteretic oxygen-depleting sodium alginate gel blocking agent; The absolute value of the HOMO orbital energy increases the most, and the energy level difference (ELUMO - EHOMO) of the complexes increases the most; the natural bonding orbital analysis reveals that the lone pair of electrons of S atoms in -CH2-SH under the environment of hysteresis oxygen depletion sodium alginate gel blocker has a strong coordination effect with Na+ and Mg2+. In the hysteresis oxygen depletion sodium alginate gel resist environment, the stability of the coordination blocking structure is strengthened due to the moderateness of the dielectric constant, and its oxygen depletion also reduces the number of O2 molecules, which further reduces the adsorption and collision chances between the two, and a more desirable blocking effect can be obtained. The results reveal the micro-mechanism of the hysteresis oxygen depletion inhibitor in preventing spontaneous combustion of coal, which can provide a reference for further improving the inhibition effect of the inhibitor.

Tutton salt (NH4)2Zn(SO4)2(H2O)6: thermostructural, spectroscopic, Hirshfeld surface, and DFT investigations

ContextAmmonium Tutton salts have been widely studied in recent years due to their thermostructural properties, which make them promising compounds for application in thermochemical energy storage devices. In this work, a detailed experimental study of the Tutton salt with the formula (NH4)2Zn(SO4)2(H2O)6 is carried out. Its structural, vibrational, and thermal properties are analyzed and discussed. Powder X-ray diffraction (PXRD) studies confirm that the compound crystallizes in a structure of a Tutton salt, with monoclinic symmetry and P21/a space group. The Hirshfeld surface analysis results indicate that the main contacts stabilizing the material crystal lattice are H···O/O···H, H···H, and O···O. In addition, a typical behavior of an insulating material is confirmed based on the electronic bandgap calculated from the band structure and experimental absorption coefficient. The Raman and infrared spectra calculated using DFT are in a good agreement with the respective experimental spectroscopic results. Thermal analysis in the range from 300 to 773 K reveals one exothermic and several endothermic events that are investigated using PXRD measurements as a function of temperature. With increasing temperature, two new structural phases are identified, one of which is resolved using the Le Bail method. Our findings suggest that the salt (NH4)2Zn(SO4)2(H2O)6 is a promising thermochemical material suitable for the development of heat storage systems, due to its low dehydration temperature (≈ 330 K), high enthalpy of dehydration (122.43 kJ/mol of H2O), and hydration after 24 h.MethodsComputational studies using Hirshfeld surfaces and void analysis are conducted to identify and quantify the intermolecular contacts occurring in the crystal structure. Furthermore, geometry optimization calculations are performed based on density functional theory (DFT) using the PBE functional and norm-conserving pseudopotentials implemented in the Cambridge Serial Total Energy Package (CASTEP). The primitive unit cell optimization was conducted using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. The electronic properties of band structure and density of states, and vibrational modes of the optimized crystal lattice are calculated and analyzed.Graphical abstract

Structural transitions in liquid semiconductor alloys: A molecular dynamics study with a neural network potential.

Liquid-liquid phase transitions hold a unique and profound significance within condensed matter physics. These transitions, while conceptually intriguing, often pose formidable computational challenges. However, recent advances in neural network (NN) potentials offer a promising avenue to effectively address these challenges. In this paper, we delve into the structural transitions of liquid CdTe, CdS, and their alloy systems using molecular dynamics simulations, harnessing the power of an NN potential named LaspNN. Our investigations encompass both pressure and temperature effects. Through our simulations, we uncover three primary liquid structures around melting points that emerge as pressure increases: tetrahedral, rock salt, and close-packed structures, which greatly resemble those of solid states. In the high-temperature regime, we observe the formation of Te chains and S dimers, providing a deeper understanding of the liquid's atomic arrangements. When examining CdSxTe1-x alloys, our findings indicate that a small substitution of S by Te atoms for S-rich alloys (x > 0.5) exhibits a structural transition much different from CdS, while a large substitution of Te by S atoms for Te-rich alloys (x < 0.5) barely exhibits a structural transition similar to CdTe. We construct a schematic diagram for liquid alloys that considers both temperature and pressure, providing a comprehensive overview of the alloy system's behavior. The local aggregation of Te atoms demonstrates a linear relationship with alloy composition x, whereas that of S atoms exhibits a nonlinear one, shedding light on the composition-dependent structural changes.

Recognition of Molecular Structure of Phosphonium Salts from the Visual Appearance of Material with Deep Learning Can Reveal Subtle Homologs.

Determining molecular structures is foundational in chemistry and biology. The notion of discerning molecular structures simply from the visual appearance of a material remained almost unthinkable until the advent of machine learning. This paper introduces a pioneering approach bridging the visual appearance of materials (both at the micro- and nanostructural levels) with traditional chemical structure analysis methods. Quaternary phosphonium salts are opted as the model compounds, given their significant roles in diverse chemical and medicinal fields and their ability to form homologs with only minute intermolecular variances. This research results in the successful creation of a neural network model capable of recognizing molecular structures from visual electron microscopy images of the material. The performance of the model is evaluated and related to the chemical nature of the studied chemicals. Additionally, unsupervised domain transfer is tested as a method to use the resulting model on optical microscopy images, as well as test models trained on optical images directly. The robustness of the method is further tested using a complex system of phosphonium salt mixtures. To the best of the authors' knowledge, this study offers the first evidence of the feasibility of discerning nearly indistinguishable molecular structures.

Li2O concentration influenced local structure and properties of molten LiCl salt by machine learning driven molecular dynamics simulation

Pyroprocessing is one of the promising technologies for the reprocessing of spent nuclear fuel. In the electrolytic reduction process of pyroprocessing, LiCl serves as the electrolyte with a minor addition of Li2O as the initial oxygen ion input. Investigating the impact of Li2O concentration on the molten salt system is essential for enhancing the efficiency of electrolytic reduction. In the present study, the LiCl-Li2O system is simulated using deep potential molecular dynamics simulation. The properties including self-diffusion coefficient, shear viscosity, ionic conductivity, heat capacity, radial distribution functions, coordination numbers, short-range order, medium-range order, Voronoi structure, and angle distribution functions are explored at different Li2O concentrations. This study reveals that the variations of physical properties at different Li2O concentrations in LiCl molten salt can be attributed to the changes in local structure. For example, unnormal high proportions of two Voronoi structures are found in the molten salt when the Li2O concentration increases, which may explain the changes of properties. These findings offer valuable insights for refining the parameters of electrolytic reduction and elucidating the correlation between microscopic and macroscopic phenomena.

Crystal structures and properties of derivatives of the alkaloid matrine: salts and hydrate forms.

We report the crystal structures of three matrine derivatives, namely, the salts (1R,2R,9S,17S)-6-oxo-7,13-diazatetracyclo[7.7.1.02,7.013,17]heptadecan-13-ium (2E)-3-(3,4-dihydroxyphenyl)prop-2-enoate (matrine caffeinate) sesquihydrate, C15H25N2O+·C9H7O4-·1.5H2O (Matrine-CA), and the 2-hydroxybenzoate (salicylate) monohydrate, C15H25N2O+·C7H5O3-·H2O (Matrine-SA), as well as the 1.75-hydrate form, (1R,2R,9S,17S)-7,13-diazatetracyclo[7.7.1.02,7.013,17]heptadecan-6-one 1.75-hydrate, C15H24N2O·1.75H2O (Matrine-H). Each derivative exhibited a consistent molecular conformation for the matrine core, which is notably distinct from that of the anhydrous form. Notably, both salts crystallized in the orthorhombic space group P212121, with an asymmetric unit featuring one cation and one anion. Within the two salt structures, intermolecular proton transfer between matrine and the acid is observed, culminating in the formation of a matrine cation protonated at the tertiary amine N site. The Matrine-CA crystal packing is manifested as a three-dimensional (3D) network arising from one-dimensional (1D) supramolecular helical chains, stabilized by N-H...O and O-H...O hydrogen bonds. In the case of Matrine-SA, the matrine cation is interconnected via hydrogen bonds with salicylate anions and water molecules, also forming a 1D helical motif. The structure of the hydrate form, Matrine-H, is reported again with the disordered solvent molecules accurately located. To further elucidate the structural attributes, Hirshfeld surface analysis and fingerprint plots are employed, offering a nuanced perspective on the intermolecular contacts and interactions within these crystalline forms.

Structure, Composition and Electrochemical Properties of Disordered Rock-Salt LiCoO2 Thin Films Prepared by Ion Beam Assisted Deposition

Ion beam assisted deposition is a method used to deposit thin films while irradiating the growing film with an ion beam. This technique is known to be effective in crystallization and orientation control at low temperatures. In this study, LiCoO2 (LCO) thin films were prepared at temperatures below 100 °C using ion beam assisted pulsed laser deposition. The structure, composition, and electrochemical properties of these films were characterized. The results indicated that LCO thin films with a disordered rock salt structure and triaxial orientation were successfully grown on polycrystalline aluminum and quartz glass substrates using ion beam assisted deposition. Furthermore, the diffusion coefficient of Li ions and the charge/discharge capacity were significantly improved compared to LCO thin films with a disordered rock salt structure prepared without the ion beam assisted process.

On the synthesis and formability of high-entropy oxides

This paper reports on a straightforward and general solution-based synthesis method for high-entropy oxides (HEOs) of different types and compositions. The flexibility and simplicity of this method are hoped to drive development of new HEOs and study of their properties and applications. Thirteen HEOs with rock salt, fluorite, spinel, and perovskite structures were synthesized using a Pechini-type synthesis at temperatures significantly lower than those necessary in solid-state synthesis (400–900 °C). Metal nitrates, nitrites, chlorides, and even water-sensitive alkoxides were used as the metal precursors with the present method. The HEOs were characterized using powder X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Relaxation of cation size and charge rules and formability of HEOs are also discussed. The present results indicate that the classical criteria for material stability do not readily translate to high-entropy systems. For example, the well-known criteria for Goldschmidt and octahedral tolerance factors established for ordinary perovskites do not seem to describe formability of perovskite HEOs well. The discussed relaxation of cation size and charge rules will contribute to the understanding of HEO systems and development of new HEO phases.

Rejuvenating exploration opportunities in Egypt's Mediterranean region using basin-scale 3D seismic reprocessing and subsurface evaluations

The Eastern Mediterranean region has proven to be a key province for natural gas resources over the last two decades. Gas discoveries in the Nile Delta Basin, Levantine Basin, and over the Eratosthenes platform have proven that an efficient working petroleum system extends to the deepwater areas and into the distal parts of the Nile Delta and Levantine basins. While the suprasalt biogenic post-Messinian play is adequately imaged in various areas in the Eastern Mediterranean region, seismic imaging of the deeper subsalt pre-Messinian plays is challenged by legacy seismic acquisition and processing techniques. Moreover, the complexity of the Messinian salt structures and the heterogeneity of the lithology of the Messinian layer across the Mediterranean basins represent a key subsurface challenge. In phase 1 of the study presented in this paper, we reprocessed 12 legacy 3D seismic data sets over 12,000 km2 and constructed a consistent basin-scale earth model from the shelf areas offshore Sinai to the deepwater areas around the Zohr carbonate platform. The data processing and imaging sequences incorporate full-waveform inversion and tomography in the earth model building process followed by a basin-to-lead evaluation to delineate exploration opportunities in phase 1. The evaluations resulted in delineating Cretaceous and Oligo-Miocene untested structures. Furthermore, potential deepwater Lower Miocene sand fairways were outlined, supported by improved regional seismic imaging and consistent seismic attributes over multiple legacy surveys. The authors of this paper expect to update the results of their work after completing the earth model building and the prestack depth migration workflows of an additional 13 legacy surveys over 35,000 km2 in phase 2 of the study.

Innovative solutions to frontier exploration in Eastern Mediterranean salt basins

The Eastern Mediterranean region is expected to hold large undiscovered natural gas resources that could address critical energy supply needs of the surrounding countries. However, exploration is challenged due to regional geologic complexities. The combination of Messinian salt structures and diapiric shales in offshore Cyprus and Egypt often causes strong attenuation of seismic energy and severe seismic imaging illumination shadows, which lead to large uncertainty regarding subsalt reservoir presence and the underlying petroleum system assessment. As part of the efforts to solve these imaging challenges, we present innovative seismic acquisition solutions to address key exploration risks such as reservoir presence. A one-sided wide-azimuth configuration consisting of one streamer vessel and one dedicated source vessel operating under the simultaneous-source mode was used to acquire data in a cost-effective way. An 8000 in3 low-frequency source was used on both vessels to provide higher energy output in the low-frequency bands of less than approximately 4 Hz. Our preliminary results show evidence of seismic image uplift due to enhanced acquisition and processing, leading to greater confidence in interpretation, which is critical for positioning wells in future drilling campaigns. This paper highlights seismic testing results undertaken to design a large exploration-scale seismic survey in the Eastern Mediterranean and early results from the execution of that program. This will help better refine optimal design criteria for future acquisition, signal processing, and imaging in order to unlock additional resources beneath complex salt provinces and identify where additional imaging needs still exist.

Three-dimensional alkaline earth metal-organic framework poly[[μ-aqua-aqua-bis-(μ3-carba-moyl-cyano-nitro-somethanido)barium] monohydrate] and its thermal decomposition.

In the structure of the title salt, {[Ba(μ3-C3H2N3O2)2(μ-H2O)(H2O)]·H2O} n , the barium ion and all three oxygen atoms of the water mol-ecules reside on a mirror plane. The hydrogen atoms of the bridging water and the solvate water mol-ecules are arranged across a mirror plane whereas all atoms of the monodentate aqua ligand are situated on this mirror plane. The distorted ninefold coord-ination of the Ba ions is completed with four nitroso-, two carbonyl- and three aqua-O atoms at the distances of 2.763 (3)-2.961 (4) Å and it is best described as tricapped trigonal prism. The three-dimensional framework structure is formed by face-sharing of the trigonal prisms, via μ-nitroso- and μ-aqua-O atoms, and also by the bridging coordination of the anions via carbonyl-O atoms occupying two out of the three cap positions. The solvate water mol-ecules populate the crystal channels and facilitate a set of four directional hydrogen bonds. The principal Ba-carbamoyl-cyano-nitro-somethanido linkage reveals a rare example of the inherently polar binodal six- and three-coordinated bipartite topology (three-letter notation sit). It suggests that small resonance-stabilized cyano-nitroso anions can be utilized as bridging ligands for the supra-molecular synthesis of MOF solids. Such an outcome may be anti-cipated for a broader range of hard Lewis acidic alkaline earth metal ions, which perfectly match the coordination preferences of highly nucleophilic nitroso-O atoms. Thermal analysis reveals two-stage dehydration of the title compound (383 and 473 K) followed by decomposition with release of CO2, HCN and H2O at 558 K.

An approach to Molten Salt Reactor operation and control and its application to the ARAMIS actinide burner

Molten salt reactors (MSRs) are Generation IV nuclear reactor concepts gaining significant research interest worldwide. The present work proposes a methodology for the definition and optimization of the MSR operating conditions and control strategy. The proposed methodology employs a novel 0D steady-state model, the multi-physics system-scale MOSAICS (MOlten SAlt Incompressible Calculation System) model and a Global Sensitivity Analysis (GSA) method based on Hilbert-Schmidt Independence Criterion indices. The methodology was then applied to the ARAMIS (Advanced Reactor for Actinides Management in Salt) fast-spectrum chloride-salt burner reactor. Two alternative control strategies are proposed in order to achieve target margins to the salt freezing and structure material limit temperatures during normal operation, plus a 20 % power variation per minute load-following objective. The performance of the control strategies was assessed through comparison with the natural behavior during a load-increasing transient, as well as during Unprotected Transient Over-Power (UTOP) and Station Blackout (SBO) accidents. Controlled load variation transients are observed to reduce overall temperature variation rates throughout the salt circuits, while the inclusion of a variable fuel flow from the reactor commands can further limit these fluctuations. However, the selected operating conditions exhibited insufficient margins to freezing or the materials limit temperature under unprotected accident conditions. GSA enabled the derivation of correlations to characterize the dynamic response of MSRs to the accidents. Based on the observed reactor response to the various transients, potential modifications to the ARAMIS design and control strategies are proposed.