Solvothermal reaction of magnesium nitrate and boron oxide in N,N-dimethylformamide produced a number of particularly complex supramolecular magnesium borates. Five topologically different types of negatively charged {Mg@[B18φ34-35]}-clusters, φ = O, OH, were observed with the magnesium cation as a core and octadecaborate anions as shells. The clusters assemble via common borate polyhedra forming 1D chains, a 2D mesoporous layer, and 3D mesoporous frameworks with an effective channel width of up to 16 Å. Topological analysis of the clusters in combination with the modular crystallography approach indicates that numerous new functional materials can be obtained by varying their assembly mode. At least one compound containing such clusters exhibits a very strong luminescence.
It is generally accepted that aragonite crystals of biogenic origin are characterized by significantly higher twin densities compared to samples formed during geological processes. Based on our single crystal X-ray diffraction (SCXRD) and transmission electron microscopy (TEM) study of aragonite crystals from various localities, we show that in geological aragonites, the twin densities are comparable to those of the samples from crossed lamellar zones of molluscs shells. The high twin density is consistent with performed calculations, according to which the Gibbs free energy of twin-free aragonite is close to that of periodically twinned aragonite structure. In some cases, high twin densities result in the appearance of diffuse scattering in SCXRD patterns. The obtained TEM and optical micrographs show that besides the twin boundaries (TBs) of growth origin, there are also TBs and especially stacking faults that were likely formed as the result of local strain compensation. SCXRD patterns of the samples from Tazouta, in addition to diffuse scattering lines, show Debye arcs in the [Formula: see text] plane. These Debye arcs are present only on one side of the Bragg reflections and have an azimuthal extent of nearly 30°, making the whole symmetry of the diffraction pattern distinctly chiral, which has not yet been reported for aragonite. By analogy with biogenic calcite crystals, we associate these arcs with the presence of misoriented subgrains formed as a result of crystal twisting during growth.
Single crystals of two new intermetallic phases Sm2Mn1-xGa6-yGey (x = 0.1-0.3, y = 0.6-1.0) and Sm4MnGa12-yGey (y = 3.0-3.5) were grown using a self-flux technique. According to single crystal X-ray diffraction data, Sm4MnGa12-yGey is characterised by the Y4PdGa12 structure type (a â¼ 8.65 Å; Im3Ìm), while Sm2Mn1-xGa6-yGey formally adopts the K2PtCl6 structure type (a â¼ 8.71 Å; Fm3Ìm). The general features of both compounds with rather similar crystal structures are represented by the alternation of empty and Mn-filled p-element octahedra, the order of which is determined by the Mn concentration. The diffraction data for Sm2Mn1-xGa6-yGey reveal a large concentration of Mn vacancies (x â¼ 0.3), which affects adjacent Ga/Ge atoms leading to their shift towards the vacancy. Both compounds demonstrate two ferromagnetic-like transitions and the presence of two interacting Mn and Sm magnetic sublattices. The Mn sublattice orders at TC1 of 143 K and 318 K, while the Sm one orders at lower temperatures at TC2 of 50 K and 280 K for Sm4MnGa8.6Ge3.4 and Sm2Mn0.74Ga5.1Ge0.9, respectively. The increase in Mn content not only increases the ordering temperatures, but also dramatically decreases the coercivity µ0HC from 230 mT to just 6.5 mT at 2 K. Despite the presence of two magnetically active sublattices in Sm2Mn0.74Ga5.1Ge0.9, the magnetic entropy change is quite low and only reaches 0.3 J kg-1 K-1 at T = 300 K and µ0H = 5 T, while the estimated relative cooling power (RCP) is about 36 J kg-1 at 5 T.
VO and VO2 vanadyl groups with short (typically 1.57-1.68â Å), essentially covalent, V-O bonds are common for V4+-bearing oxysalts with [5]- and [6]-coordinated vanadium. There is a clear negative correlation between vanadyl bond lengths and wavenumbers of the bands of V-O stretching vibrations in infrared spectra (in the range 1000-880â cm-1). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone-Dale compatibility coefficients. Gladstone-Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabilities of V4+. Unlike compounds of [5]-coordinated Ti4+, for most minerals with V4+=O (vanadyl) bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept.
The study of azoproite by Biryukov et al. [Acta Cryst. (2022), B78, 809-816) continues the systematic and complex investigation of the crystal structures, temperature behavior and magnetic properties of natural oxoborates.
Compounds with the general formula Ln3+(SeO3)(HSeO3)·2H2O, where Ln = Sm3+, Tb3+, Nd3+ and Lu3+, are characterized by orthorhombic symmetry with space group P212121 and unit-cell parameters in the ranges a â¼ 6.473-6.999, b â¼ 6.845-7.101, c â¼ 16.242-16.426â Å. Light-purple irregularly shaped crystals of a new monoclinic polytype of neodymium selenite Nd(SeO3)(HSeO3)·2H2O have been obtained during a mild-condition hydrothermal synthesis. The monoclinic unit-cell parameters are: a = 7.0815â (2), b = 6.6996â (2), c = 16.7734â (5)â Å, ß = 101.256â (1)°, V = 780.48â (6)â Å3; space group P21/c. The crystal structures of Nd(SeO3)(HSeO3)·2H2O polymorphs show order-disorder (OD) character and can be described using the same OD groupoid family, more precisely a family of OD structures built up from two kinds of non-polar layers (category IV). The first monoclinic maximum degree order (MDO) structure (MDO1-polytype) with space group P21/c can be obtained when the inversion centre is active in the L2n-type layers, while the second MDO structure (MDO2-polytype) is orthorhombic with space group P212121 and can be obtained when the [21--] operation is active in the L2n-type layers. The structural complexity parameters and DFT calculations of both polytypes show that the polytype structures are extremely close energy-wise and almost equally viable from the point of total energy of the structure.
Most known compounds with five-coordinated Ti4+ are natural and synthetic titanosilicates. The crystal structure of natural fresnoite, Ba2TiSi2O8 [tetragonal, space group P4bm, a = 8.510â (1)â Å, c = 5.197â (1)â Å, V = 376.4â (1)â Å3, Z = 2], has been refined to R = 0.011 on the basis of 807 unique single-crystal reflections with I > 2σ(I). Titanium has fivefold coordination with one short (`titanyl') bond of 1.692â (5)â Å. Bonds in the TiO5 polyhedron are discussed in comparison to analogous coordination polyhedra in other minerals and compounds. A review of all known compounds with Ti4+O5 polyhedra shows that most of them are titanosilicates in which titanium forms a short Ti-O bond (â¼1.61 to â¼1.77â Å). Poor Gladstone-Dale compatibility between chemical composition, optical characteristics and density of these compounds is explained by the anomalous contribution of [5]Ti4+ to the optical properties as shown by calculations based on the relationship between electronic polarizabilities and refractive indices. An improved Gladstone-Dale coefficient of 0.29 is suggested for TiO2 with [5]Ti4+. A negative correlation between `titanyl' bond lengths and wavenumbers of the bands of Ti-O stretching vibrations (in the range of 890-830â cm-1) in infrared and Raman spectra is observed.
Using glass crystallization and solid-state techniques, we were able to complete the family of salt-inclusion silver halide borates, Ag4B7O12X, by the X = Cl and I members. The new compounds are characterized by differential scanning calorimetry, single-crystal and high-temperature powder X-ray diffraction, optical spectroscopy, and density functional theory calculations. In all structures, the silver atoms exhibit strong anharmonicity of thermal vibrations, which could be modeled using Gram-Charlier expansion, and its asymmetry was characterized by the skewness vector. The topology of the silver halide and borate sublattices has been analyzed separately for the first time. Along the I â Br â Cl series, we observe a decrease of the melting point and configuration entropy and an increase of thermal expansion and its anisotropy and thermal vibration anharmonicity, which indicates decreasing stability.
The identification of the framework type in multilayer cancrinite- and sodalite-group minerals and synthetic compounds is predominantly based on the unit-cell dimensions determined from powder or single-crystal X-ray diffraction data, by analogy with previously characterized samples with known crystal structures. However, topological type of the framework cannot be reliably determined in this way because of the different possible ABC staking sequences and different sets of cages with the same number of layers in the repeat unit. To solve this problem, additional criteria are required. The use of infrared (IR) spectroscopy makes it possible to distinguish topologically different types with the same unit-cell parameters. The most important diagnostic range in the IR spectrum (the "finger-print region", from 510 to 760 cm-1) corresponds to the O-T-O bending vibrations (T = Si, Al). The spectral bands at 705 ± 8, 528 ± 5, 547 ± 4, and 555 ± 3 cm-1 indicate the presence of the sodalite, Losod, liottite, and giuseppettite cages, respectively. The band at 528 ± 5 cm-1 shifts towards â¼518 cm-1 in the case when Losod cage hosts carbonate group. The IR spectrum in the "finger-print region" can be also used to identify a mineral species belonging to two-layer or three-layer minerals with different extra-framework compositions. The wavenumber of the antisymmetric stretching mode of the 12CO2 molecule, which is a common admixed extra-framework constituent in minerals belonging to the cancrinite and sodalite groups, depends on the kind of the host cage or channel: 2340-2343 cm-1 for the sodalite cage, 2338 cm-1 for the Losod cage, and 2351-2353 cm-1 for the liottite cage and wide channel in the cancrinite-type framework.
A new series of Sr-based phosphates, Sr9-xMnxEu(PO4)7, were synthesized using the high-temperature solid-state method in air. It was found that these compounds have the same structure as strontiowhitlockite, which is a ß-Ca3(PO4)2 (or ß-TCP) structure. The concentration of Mn2+ ions required to form a pure strontiowhitlockite phase was determined. An unusual partial reduction of Eu3+ to Eu2+ in air was observed and confirmed by photoluminescence (PL) and electron spin resonance (ESR) spectra measurements. The PL spectra recorded under 370 nm excitation showed transitions of both 4f5d-4f Eu2+ and 4f-4f Eu3+. The total integral intensity of the PL spectra, monitored at 395 nm, decreased with increasing Mn2+ concentration due to quenching effect of Eu3+ by the Mn2+ levels. The temperature dependence of Eu2+ photoluminescence in a Sr9-xMnxEu(PO4)7 host was investigated. The conditions for the reduction of Eu3+ to Eu2+ in air were discussed.
ß-Tricalcium phosphate (ß-TCP) is widely used as bone implant material. It has been observed that doping the ß-TCP structure with certain cations can help in combating bacteria and pathogenic microorganisms. Previous literature investigations have focused on tricalcium phosphate structures with silver, copper, zinc, and iron cations. However, there are limited studies available on the biological properties of ß-TCP containing nickel and cobalt ions. In this work, Ca10.5-xNix(PO4)7 and Ca10.5-xCox(PO4)7 solid solutions with the ß-Ca3(PO4)2 structure were synthesized by a high-temperature solid-state reaction. Structural studies revealed the ß-TCP structure becomes saturated at 9.5 mol/% for Co2+ or Ni2+ ions. Beyond this saturation point, Ni2+ and Co2+ ions form impurity phases after complete occupying of the octahedral M5 site. The incorporation of these ions into the ß-TCP crystal structure delays the phase transition to the α-TCP phase and stabilizes the structure as the temperature increases. Biocompatibility tests conducted on adipose tissue-derived mesenchymal stem cells (aMSC) using the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay showed that all prepared samples did not exhibit cytotoxic effects. Furthermore, there was no inhibition of cell differentiation into the osteogenic lineage. Antibacterial properties were studied on the C. albicans fungus and on E. coli, E. faecalis, S. aureus, and P. aeruginosa bacteria strains. The Ni- and Co-doped ß-TCP series exhibited varying degrees of bacterial growth inhibition depending on the doping ion concentration and the specific bacteria strain or fungus. The combination of antibacterial activity and cell-friendly properties makes these phosphates promising candidates for anti-infection bone substitute materials.
The crystal structure of Na2Mn3(SO4)4 [unit-cell parameters a = 14.8307â (18), b = 9.9107â (18), c = 8.6845â (12)â Å, space group Cmc21] displays order-disorder (OD) character and can be described using the OD groupoid family, more precisely a family of OD structures built up by two types of non-polar layers, with layer symmetry P(m)c21 (L2n+1 type) and P(b)cm (L2n type) (category IV). A new hypothetical MDO2 polytype has been proposed and the geometry optimization demonstrates its reasonability as another possible stable polytype. Compounds Na2Mn3-xMgx(SO4)4 with the unit-cell parameters a â¼ 29.2-29.7â Å, b â¼ 9.5-9.9â Å, c â¼ 8.7â Å and space group Pbca can be described in terms of modularity as a sequence of A, S1 and S2 modules: |AS1AS2AS1AS2| or (AS1AS2), together with MDO1 (AS1AS1) and MDO2 (AS2AS2). The crystal structures of itelmenite, NaCaFe3+3(PO4)4, and Ca2MgFe3+2(PO4)4 are crystal-chemical isotypic to Na2Mn3-xMgx(SO4)4 and should be considered as (A*S1A*S2) derivatives of the (AS1AS2)-type structure.
Density Functional Theory , Ions
Topological analysis of the heteropolyhedral MT framework (where M and T are octahedral and tetrahedral cations, respectively) in the eudialyte-type structure and its derivatives was performed based on a natural tiling analysis of the 3D cation. To analyze the migration paths of sodium cations in these structures, the Voronoi method was used. The parental eudialyte-type MT framework is formed by isolated ZO6 octahedra, six-membered [M(1)6O24] rings of edge-sharing M(1)O6 octahedra, and two kinds of rings of tetrahedra, [Si3O9] and [Si9O27]. Different occupancies of M(2), M(3) and M(4) sites with variable coordination numbers by the additional Q, T* and M* cations, respectively, result in 12 different types of the MT framework. Based on the results of natural tilings calculations as well as theoretical analysis of migration paths, it is found that Na+ ions can migrate through six- and seven-membered rings, while all other rings are too small for the migration. In eight types of MT frameworks, Na+-ion migration and diffusion is possible at ambient temperature and pressure, while in four other types cages are connected by narrow windows and, as a result, the Na+ diffusion in them is complicated at ambient conditions because of the window diameter, but may be possible either at higher temperatures or under mild geological conditions for long periods of time.
Sodium , Cations , Models, Molecular
A series of solid-solution phosphate germanates Ca8+0.5xZnEu(PO4)7-x(GeO4)x (x = 0, 0.2, 0, 4, 0.6, 0.8, 1) with the ß-Ca3(PO4)2-type structure were synthesized by solid-state reactions. The limit of existence of a single-phase solid solution was determined by X-ray diffraction patterns and it was found at x = 0.8. The heterovalent tetrahedral [PO4]3- â [GeO4]4- substitution requires a charge compensation according to the scheme: [PO4]3- + ½ â¡ â [GeO4]4- + ½ Ca2+. The additional amount of Ca2+ ions in the crystal structure was detected at the M4 site during Rietveld refinement. It was shown that in ß-Ca3(PO4)2-type compounds, charge balancing is not provided by the randomly distributed oxygen vacancies but only by the partial occupancy of the M4 site. The presence of Ca2+ at the M4 site leads to a polar structure with the space group R3c which was confirmed by an SHG test for all single-phase samples. It was shown that the Ge4+ ions preferably occupy the T3 site in the structure, which is connected through common oxygen with the cationic M1-M5 sites. The analysis of the similarity of the previously reported Ca9La(GeO4)0.75(PO4)6 compound reveals an unexpectedly high value. The same structural similarity evaluation of the studied compound Ca8.1EuZn(PO4)6.8(GeO4)0.2 in the present work with the initial model gives a very small value, which indicates a good match between the initial and under-consideration structures. The luminescence properties of Eu3+ were investigated from the point of view of crystal structures and anionic substitutions. The integral intensity increased linearly with the [PO4]3- â [GeO4]4- substitution. It can be concluded that the anionic substitution on Ge4+ can improve the luminescence characteristics. The present study includes new data on the anionic substitution based on accurate crystal structure refinement.
Specific features of the crystal chemistry of lamprophyllite-group minerals (LGMs) are discussed using the available literature data and the results of the single-crystal X-ray diffraction and a Raman spectroscopic studies of several samples taken from the Murun alkaline complex (Russia), and Rocky Boy and Gordon Butte pegmatites (USA) presented here. The studied samples are unique in their chemical features and the distribution of cations over structural sites. In particular, the sample from the Gordon Butte pegmatite is a member of the barytolamprophyllite-emmerichite solid solution series, whereas the samples from the Murun alkaline complex and from the Rocky Boy pegmatite are intermediate members of the solid solution series formed by lamprophyllite and a hypothetical Sr analogue of emmerichite. The predominance of O2- over OH- and F- at the X site is a specific feature of sample Cha-192 from the Murun alkaline complex. New data on the Raman spectra of LGMs obtained in this work show that the wavenumbers of the O-H stretching vibrations depend on the occupancies of the M2 and M3 sites coordinating with (OH)- groups. Cations other than Na+ and Ti4+ (mainly, Mg and Fe3+) can play a significant role in the coordination of the X site occupied by (OH)-. Data on polarized Raman spectra of an oriented sample indicate that the OH groups having different local coordinations have similar orientations with respect to the crystal. The calculated measures of similarity (Δ) for lamprophyllite and ericssonite are identical (0.157 and 0.077 for the 2M- and 2O-polytypes, respectively), which indicates that these minerals are crystal-chemically isotypic and probably should be considered within the same mineral group by analogy to the other mineralogical groups which combine isotypic minerals.
Verinurad, a uric acid transporter 1 (URAT1) inhibitor, lowers serum uric acid by promoting its urinary excretion. Co-administration with a xanthine oxidase inhibitor (XOI) to simultaneously reduce uric acid production rate reduces the potential for renal tubular precipitation of uric acid, which can lead to acute kidney injury. The combination is currently in development for chronic kidney disease and heart failure. The aim of this work was to apply and extend a previously developed semi-mechanistic exposure-response model for uric acid kinetics to include between-subject variability to verinurad and its combinations with XOIs, and to provide predictions to support future treatment strategies. The model was developed using data from 12 clinical studies from a total of 434 individuals, including healthy volunteers, patients with hyperuricemia, and renally impaired subjects. The model described the data well, taking into account the impact of various patient characteristics such as renal function, baseline fractional excretion of uric acid, and race. The potencies (EC50s) of verinurad (reducing uric acid reuptake), febuxostat (reducing uric acid production), and oxypurinol (reducing uric acid production) were: 29, 128, and 13,030 ng/mL, respectively. For verinurad, symptomatic hyperuricemic (gout) subjects showed a higher EC50 compared with healthy volunteers (37 ng/mL versus 29 ng/mL); while no significant difference was found for asymptomatic hyperuricemic patients. Simulations based on the uric acid model were performed to assess dose-response of verinurad in combination with XOI, and to investigate the impact of covariates. The simulations demonstrated application of the model to support dose selection for verinurad.
Hyperuricemia/drug therapy , Naphthalenes/therapeutic use , Organic Anion Transporters/antagonists & inhibitors , Organic Cation Transport Proteins/antagonists & inhibitors , Propionates/therapeutic use , Pyridines/therapeutic use , Uric Acid/blood , Adult , Aged , Aged, 80 and over , Drug Therapy, Combination , Female , Humans , Hyperuricemia/blood , Hyperuricemia/urine , Kidney/drug effects , Male , Middle Aged , Models, Statistical , Naphthalenes/administration & dosage , Naphthalenes/pharmacology , Propionates/administration & dosage , Propionates/pharmacology , Pyridines/administration & dosage , Pyridines/pharmacology , Uric Acid/urine , Xanthine Oxidase/antagonists & inhibitors , Young Adult
The series of ß-Ca3(PO4)2-type phosphors Ca9.5-1.5xMgEux(PO4)7 were synthesized by a solid-state route. Observation of the proper Eu3+ ion distribution in the Ca9.5Mg(PO4)7 host matrix was made by a direct method using 151Eu Mössbauer spectroscopy in combination with X-ray analysis and dielectric and luminescent spectroscopy. The photoluminescence properties were studied in detail. The samples exhibit an exceptionally narrow-band red emission according to the dominant 5D0 â 7F2 transition and fulfill the industrial requirements for high-energy-efficiency red phosphors. The contribution of Eu3+ ions in different crystal sites to the luminescent properties is discussed in detail. The difference of the excitation of Eu3+ in the M1 and M2 sites was revealed by photoluminescence excitation spectra in accordance with structure refinement. The temperature dependence of the luminescence intensity was studied. Different tendencies in the thermal behavior of emission lines allow one to consider the studied compounds as phosphors suitable for luminescence thermometry. The measured quantum yield for Ca9.5-1.5xMgEux(PO4)7 shows excellent results and reaches 63%.
Two uranyl vanadate heteropolyoxometalates (h-POMs) have been synthesized by ionothermal methods using the ionic liquid 1-ethyl-3-methylimidazolium diethyl phosphate (EMIm-Et2PO4). The hybrid actinide-transition metal shell structures have cores of (UO2)8(V6O22) and (UO2)6(V3O12), which we designate as {U8V6} and {U6V3}, respectively. The diethyl phosphate anions of the ionic liquids in some cases terminate the core structures to form actinyl oxide clusters, and in other cases the diethyl phosphate oxyanions link these cluster cores into extended structures. Three compounds exist for the {U8V6} cluster core: {U8V6}-monomer, {U8V6}-dimer, and {U8V6}-chain. Tungsten atoms can partially substitute for vanadium in the {U6V3} cluster, which results in a chain-based structure designated as {U6V3}-W. Each of these compounds contains charge-balancing EMIm cations from the ionic liquid. These compounds were characterized crystallographically, spectroscopically, and by mass spectrometry.
Therapy optimization remains an important challenge in the treatment of advanced non-small cell lung cancer (NSCLC). We investigated tumor size (sum of the longest diameters (SLD) of target lesions) and neutrophil-to-lymphocyte ratio (NLR) as longitudinal biomarkers for survival prediction. Data sets from 335 patients with NSCLC from study NCT02087423 and 202 patients with NSCLC from study NCT01693562 of durvalumab were used for model qualification and validation, respectively. Nonlinear Bayesian joint models were designed to assess the impact of longitudinal measurements of SLD and NLR on patient subgrouping (by Response Evaluation Criteria in Solid Tumors 1.1 criteria at 3 months after therapy start), long-term survival, and precision of survival predictions. Various validation scenarios were investigated. We determined a more distinct patient subgrouping and a substantial increase in the precision of survival estimates after the incorporation of longitudinal measurements. The highest performance was achieved using a multivariate SLD and NLR model, which enabled predictions of NSCLC clinical outcomes.
Antibodies, Monoclonal/therapeutic use , Antineoplastic Agents, Immunological/therapeutic use , Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Lymphocytes/drug effects , Models, Biological , Neutrophils/drug effects , Tumor Burden/drug effects , Adult , Aged , Aged, 80 and over , Bayes Theorem , Biomarkers , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/immunology , Carcinoma, Non-Small-Cell Lung/mortality , Clinical Trials, Phase I as Topic , Clinical Trials, Phase II as Topic , Female , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/immunology , Lung Neoplasms/mortality , Male , Middle Aged , Prognosis , Proportional Hazards Models , Reproducibility of Results
