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Objectives In older patients, the diagnosis of acute pyelonephritis (APN) is challenging. The aim was to evaluate the added value of CT to history, physical examination and urinalysis for the diagnosis of APN in older patients with suspected infection with an unknown focus.Design Retrospective diagnostic study.Setting Department of General Medicine in an acute care hospital in Japan.Participants Patients aged ≥65 years who underwent blood cultures, a urine culture, and chest and abdominal CT to detect the focus of infection were included.Primary outcome measures Two radiologists independently reviewed four non-contrast CT signs: perirenal fat stranding, pelvicalyceal wall thickening, enlargement of the kidney and thickening of Gerota’s fascia. Findings on contrast-enhanced CT could not be evaluated due to an insufficient number of patients in whom contrast-enhanced CT was performed. An expert panel was used as the reference standard for APN. The added value of CT findings was quantified by comparing the diagnostic performance between a model based on 10 predictors available before CT and an extended model including the CT findings.Results Of 473 patients, 61 (14.8%) were diagnosed with APN. When the laterality of the CT findings was taken into account, the model fit was not improved by adding them. In the laterality-insensitive analysis, the model performance was significantly improved by adding the CT signs (likelihood-ratio test p=0.03; c-index 0.89 vs 0.91, p=0.03). However, their clinical utility was only to improve the classification of 11.5% of patients with APN.Conclusions The added value of non-contrast CT findings to history, physical examination and urinalysis was limited for the diagnosis of APN in older patients with a suspected infection with an unknown focus.

Abstract Proton conductors have found diverse applications, such as electrolytes in proton ceramic fuel cells, which require high ionic conductivity at low temperatures and high chemical stability. Here, we report the oxide, Ba2LuAlO5, which exhibits proton conductivities of 10− 2 S cm− 1 at 487 °C and 1.5 × 10− 3 S cm− 1 at 232 °C, high diffusivity and high chemical stability without chemical doping. Ba2LuAlO5 is a hexagonal perovskite-related oxide with highly oxygen-deficient hexagonal close-packed h′ layers, which enables a large amount of water uptake x = 0.50 in Ba2LuAlO5·x H2O. Ab initio molecular dynamics simulations and neutron diffraction show the hydration in the h′ layer and proton migration mainly around cubic close-packed c layers existing at the interface of octahedral LuO6 layers. These results demonstrate that the high proton conduction allowed by the highly oxygen-deficient and cubic close-packed layers is a promising strategy for the development of high-performance proton conductors.

Abstract The chemical order and disorder of solids have a decisive influence on the material properties. There are numerous materials exhibiting chemical order/disorder of atoms with similar X-ray atomic scattering factors and similar neutron scattering lengths. It is difficult to investigate such order/disorder hidden in the data obtained from conventional diffraction methods. Herein, we quantitatively determined the Mo/Nb order in the high ion conductor Ba7Nb4MoO20 by a technique combining resonant X-ray diffraction, solid-state nuclear magnetic resonance (NMR) and first-principle calculations. NMR provided direct evidence that Mo atoms occupy only the M2 site near the intrinsically oxygen-deficient ion-conducting layer. Resonant X-ray diffraction determined the occupancy factors of Mo atoms at the M2 and other sites to be 0.50 and 0.00, respectively. These findings provide a basis for the development of ion conductors. This combined technique would open a new avenue for in-depth investigation of the hidden chemical order/disorder in materials.

The authors develop an RNA sequencing-based platform, PERSIST-seq, to simultaneously delineate in-cell mRNA stability, ribosome load, and in-solution stability of a diverse mRNA library to derive design principles for improved mRNA therapeutics.

As the threat of antimicrobial-resistant bacteria compromises the safety and efficacy of modern healthcare practices, the search for effective treatments is more urgent than ever. For centuries, silver (Ag) has been known to have antibacterial properties and, over the past two decades, Ag-based nanoparticles have gained traction as potential antimicrobials. The antibacterial efficacy of Ag varies with structure, size, and concentration. In the present study, we examined Ag nanoparticles (AgNPs) for their antimicrobial activity and safety. We compared different commercially-available AgNPs against gram-negative Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and gram-positive Staphylococcus aureus methicillin-resistant and susceptible strains. The most effective formula of AgNPs tested had single-digit (μg/mL) minimum inhibitory concentrations against gram-negative multidrug-resistant clinical bacterial isolates with novel and emerging mechanisms of resistance. The mode of killing was assessed in E. coli and was found to be bactericidal, which is consistent with previous studies using other AgNP formulations. We evaluated cytotoxicity by measuring physiological readouts using the Caenorhabditis elegans model and found that motility was affected, but not the lifespan. Furthermore, we found that at their antibacterial concentrations, AgNPs were non-cytotoxic to any of the mammalian cell lines tested, including macrophages, stem cells, and epithelial cells. More interestingly, our experiments revealed synergy with clinically relevant antibiotics. We found that a non-toxic and non-effective concentration of AgNPs reduced the minimum inhibitory concentrations of aminoglycoside by approximately 22-fold. Because both aminoglycosides and Ag are known to target the bacterial ribosome, we tested whether Ag could also target eukaryotic ribosomes. We measured the rate of mistranslation at bactericidal concentration and found no effect, indicating that AgNPs are not proteotoxic to the host at the tested concentrations. Collectively, our results suggest that AgNPs could have a promising clinical application as a potential stand-alone therapy or antibiotic adjuvants.

Honeycomb layered oxides are an emerging class of materials with peculiar physicochemical properties. Here, the authors report the synthesis and electrochemical energy storage characterisations of a mixed-alkali honeycomb layered oxide material capable of storing Na and K ions simultaneously.

Oxide-based lithium/sodium-rich antiperovskites are regarded as promising solid electrolytes. Here, authors report a series of antiperovskites with a soft lattice containing hydride (H–) and chalcogenide (S2–, Se2–, Te2–) anions, enabling the fast Li+ /Na+ transport assisted by rotational phonon modes.

Oxide-ion conductors are important in various applications for clean energy. Here, authors report high oxide-ion conductivity of hexagonal perovskite-related oxide Ba7Nb3.9Mo1.1O20.05, which is ascribed to the interstitialcy diffusion and low activation energy for oxide-ion conductivity.

Properties of perovskite oxides can be changed by manipulating anion-vacancy order patterns, but they are difficult to control. Here the authors show strain-induced creation and switching of anion vacancies in perovskite films in which the direction or periodicity of anion-vacancy planes is altered depending on the substrate employed.

Oxide ion conductors are an exciting class of materials with applications in various domains. Here, the authors show that Dion–Jacobson Phases are a structure supporting high O2− mobility. The bulk conductivity of CsBi2Ti2NbO10−δ even exceeds that of YSZ, offering new possibilities in electrolyte discovery.

Abstract The main approach for exploring metastable materials is via trial‐and‐error synthesis, and there is limited understanding of how metastable materials are kinetically stabilized. In this study, a metastable phase superionic conductor, β‐Li3YCl6, is discovered through in situ X‐ray diffraction after heating a mixture of LiCl and YCl3 powders. While Cl− arrangement is represented as a hexagonal close packed structure in both metastable β‐Li3YCl6 synthesized below 600 K and stable α‐Li3YCl6 above 600 K, the arrangement of Li+ and Y3+ in β‐Li3YCl6 determined by neutron diffraction brought about the cell with a 1/√3 a‐axis and a similar c‐axis of stable α‐Li3YCl6. Higher Li+ ion conductivity and lower activation energy for Li+ transport are observed in comparison with α‐Li3YCl6. The computationally calculated low migration barrier of Li+ supports the low activation energy for Li+ conduction, and the calculated high migration barrier of Y3+ kinetically stabilizes this metastable phase by impeding phase transformation to α‐Li3YCl6. This work shows that the combination of in situ observation of solid‐state reactions and computation of the migration energy can facilitate the comprehension of the solid‐state reactions allowing kinetic stabilization of metastable materials, and can enable the discovery of new metastable materials in a short time.

Single crystals of the solid solution series Ca4+xY3–xSi7O15+xN5–x were obtained by a solid-state reaction method using a flux for x = 0, 0.5 and 1, resulting in Ca4Y3Si7O15N5 (tetracalcium triyttrium heptasilicon oxynitride), Ca4.5Y2.5Si7O15.5N4.5 and Ca5Y2Si7O16N4 (pentacalcium diyttrium heptasilicon oxynitride). Single-crystal X-ray analysis revealed that the three compounds are isotypic and belong to space-group type P63/m. Ca2+ and Y3+ cations are distributed over two crystallographic sites (site symmetry \overline{3}.. and 1) in a disordered manner. The corresponding (Ca,Y)-centred polyhedra are connected by edge-sharing, resulting in the formation of a layer structure extending parallel to (001). Three [Si(O,N)]4 tetrahedra (two with point group symmetry m.., one with 3.. and half-occupancy) are condensed into an isolated [Si7(O,N)19] unit, in which an [Si(O,N)]4 tetrahedron is located at the center of a 12-membered oxynitride ring with composition [Si6O15N3]. The present compounds are the first to have such an [Si7(O,N)19] unit in their structures.

Objectives A previous study reported that food consumption is useful to rule out bacteraemia in hospitalised patients. We aimed to validate the diagnostic performance of (1) food consumption and (2) a previously reported algorithm using food consumption and shaking chills for bacteraemia in patients admitted to hospital with suspected infection.Design Prospective cohort study.Setting Department of General Medicine in two acute care hospitals in Japan.Participants A total of 2009 adult patients who underwent at least two blood cultures on admission.Primary outcome measures The reference standard for bacteraemia was judgement by two independent specialists of infectious diseases. Food consumption was evaluated by the physician in charge asking the patient or their caregivers the following question on admission: ‘What percentage of usual food intake were you able to eat during the past 24 hours?’Results Among 2009 patients, 326 patients were diagnosed with bacteraemia (16.2%). Diagnostic performance of food consumption was sensitivity of 84.4% (95% CI 80.1 to 88), specificity of 19.8% (95% CI 18 to 21.8), positive predictive value (PPV) of 16.9% (95% CI 15.2 to 18.9) and negative predictive value (NPV) of 86.8% (95% CI 83.1 to 89.8). The discriminative performance was an area under the curve of 0.53 (95% CI 0.50 to 0.56). The performance of the algorithm using food consumption and shaking chills was sensitivity of 89% (95% CI 85.1 to 91.9), specificity of 18.8% (95% CI 17 to 20.7), PPV of 17.5% (95% CI 15.7 to 19.4) and NPV of 89.8% (95% CI 86.2 to 92.5).Conclusion Our results did not show the usefulness of food consumption and the algorithm using food consumption and shaking chills for the diagnosis of bacteraemia in patients admitted to hospital with suspected infection.

Background: Writing letters to the editor based on critical appraisal can serve as the first step in scholarly activity. The workshop in this study focused on educating physicians about the best ways to write letters to the editor. Methods: We conducted a 90-minute workshop as a part of scientific conference. Participants were physicians and medical students who chose to join this workshop. We developed the following learning outcomes for participants: 1) to be able to explain falsificationism; 2) to be able to explain how to check author instructions; 3) to be able to explain how to write a letter to the editor. Results: Twenty-eight participants, including three medical students, attended the workshop. Participants' satisfaction with the workshop had a mean of 4.5 points out of 5 (standard deviation: 0.5). Nearly 80% of participants achieved the learning outcomes. Four participants' groups submitted letters within a month after the workshop, and all four were published. These four groups encompassed a total of 13 authors. In addition, none of the first author of each letter had previously written a clinical research paper. Findings and Discussion: This workshop improved not only the participants' knowledge but it also led to the concrete result of four published letters. Japanese physicians would be able to use this framework to write letters to the editor.

We report the first case of infective endocarditis following urinary tract infection (UTI) caused by Globicatella sanguinis in an 87-year-old Japanese woman with recurrent episodes of UTI. We identified the pathogen using the Rapid ID32 Strep system. Accurate identification of this infection is important and essential for the effective antimicrobial coverage to this pathogen.

Gene expression is regulated at several levels, including through the modulation of protein translation. Here the authors find that translation control diversifies gene expression between developing tissues and regulates major signalling pathways through a complex landscape of upstream open reading frames (uORFs).

Sillén–Aurivillius perovskite Bi4NbO8X (X = Cl, Br) is a promising photocatalyst for water splitting under visible light, as well as a potential ferroelectric material. In this work, we investigate the crystal growth conditions by mainly varying soak temperature, soak time and cooling rate. Under the optimal conditions, we successfully obtained yellow platelet single crystals with an in-plane distance of several hundred microns. As opposed to conventional crystal growth, a moderate cooling is essential to suppress an evaporation of the Bi–O–Cl species from a melt zone. The single crystals of Bi4NbO8Br were also grown using a similar condition. We suggest that the knowledge obtained in this study can be generally applied to other Sillén–Aurivillius phases and related oxyhalides.

The title salt, K+·C8H8NO5− [systematic name: potassium (2R,5R,Z)-3-(2-hydroxyethylidene)-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane-2-carboxylate], a widely used β-lactam antibiotic, is usually chemically unstable even in the solid state owing to its tendency to be hydrolysed. In the crystal structure, the potassium cations are arranged along the a axis, forming interactions to the carboxylate and hydroxy groups, resulting in one-dimensional ionic columns. These columns are arranged along the b axis, connected by O—H...O hydrogen bonds, forming a layer in the ab plane.

Ceramic proton conductors are important in various applications such as fuel cells. In contrast to the conventional acceptor doping into the perovskite-type oxide without oxygen vacancies, donor doping into highly oxygen deficient perovskite is a novel strategy to achieve reduced proton trapping. Here, we report high proton conduction (e.g., 10 mS cm-1 at 235 °C) and chemical stability of highly oxygen deficient perovskite, W6+-donor-doped BaScO2.5 (BaSc0.8W0.2O2.8). The high conductivity is attributed to both high proton concentration and proton diffusion coefficient D. The high D at low and intermediate temperatures is attributed to its low activation energy, suggesting reduced proton trapping. The high proton concentration is ascribed to both high oxygen deficiency in BaSc0.8W0.2O2.8 and full hydration in hydrated BaSc0.8W0.2O2.8 (BaSc0.8W0.2O3.0H0.4). A reason for the higher proton conductivity of BaSc0.8W0.2O2.8 compared with BaSc0.8Mo0.2O2.8 is higher fractional water uptake of BaSc0.8W0.2O2.8, which is attributable to the larger lattice volume of BaSc0.8W0.2O2.8 due to the larger sized W cation than the Mo cation. Present findings would open new avenues for clean energy societies. [ABSTRACT FROM AUTHOR]

As the threat of antimicrobial-resistant bacteria compromises the safety and efficacy of modern healthcare practices, the search for effective treatments is more urgent than ever. For centuries, silver (Ag) has been known to have antibacterial properties and, over the past two decades, Ag-based nanoparticles have gained traction as potential antimicrobials. The antibacterial efficacy of Ag varies with structure, size, and concentration. In the present study, we examined Ag nanoparticles (AgNPs) for their antimicrobial activity and safety. We compared different commerciallyavailable AgNPs against gram-negative Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and gram-positive Staphylococcus aureus methicillinresistant and susceptible strains. The most effective formula of AgNPs tested had single-digit (μg/mL) minimum inhibitory concentrations against gram-negative multidrug-resistant clinical bacterial isolates with novel and emerging mechanisms of resistance. The mode of killing was assessed in E. coli and was found to be bactericidal, which is consistent with previous studies using other AgNP formulations. We evaluated cytotoxicity by measuring physiological readouts using the Caenorhabditis elegans model and found that motility was affected, but not the lifespan. Furthermore, we found that at their antibacterial concentrations, AgNPs were non-cytotoxic to any of the mammalian cell lines tested, including macrophages, stem cells, and epithelial cells. More interestingly, our experiments revealed synergy with clinically relevant antibiotics. We found that a non-toxic and non-effective concentration of AgNPs reduced the minimum inhibitory concentrations of aminoglycoside by approximately 22-fold. Because both aminoglycosides and Ag are known to target the bacterial ribosome, we tested whether Ag could also target eukaryotic ribosomes. We measured the rate of mistranslation at bactericidal concentration and found no effect, indicating that AgNPs are not proteotoxic to the host at the tested concentrations. Collectively, our results suggest that AgNPs could have a promising clinical application as a potential stand-alone therapy or antibiotic adjuvants. [ABSTRACT FROM AUTHOR]

Single crystals of the solid solution series Ca4+xY3-xSi7O15+xN5-x were obtained by a solid-state reaction method using a flux for x = 0, 0.5 and 1, resulting in Ca4Y3Si7O15N5 (tetracalcium triyttrium heptasilicon oxynitride), Ca4.5Y2.5Si7O15.5N4.5 and Ca5Y2Si7O16N4 (pentacalcium diyttrium heptasilicon oxynitride). Single-crystal X-ray analysis revealed that the three compounds are isotypic and belong to space-group type P63/m. Ca2+ and Y3+ cations are distributed over two crystallographic sites (site symmetry 3.. and 1) in a disordered manner. The corresponding (Ca,Y)-centred polyhedra are connected by edge-sharing, resulting in the formation of a layer structure extending parallel to (001). Three [Si(O,N)]4 tetrahedra (two with point group symmetry m.., one with 3.. and half-occupancy) are condensed into an isolated [Si7(O,N)19] unit, in which an [Si(O,N)]4 tetrahedron is located at the center of a 12-membered oxynitride ring with composition [Si6O15N3]. The present compounds are the first to have such an [Si7(O,N)19] unit in their structures. [ABSTRACT FROM AUTHOR]

The hydride-fluoride pyrochlore NaCaMg2F7-xHx has been synthesized at high pressure (2 GPa) from binary fluorides and hydrides. Contrary to initial expectations, we did not find strong evidence of selective hydride substitution in special anionic sites. F-center formation under UV irradiation at room temperature was observed, demonstrating the potential lability of hydride and enabling further systematic studies. [ABSTRACT FROM AUTHOR]

BaNdInO4 is a new structure family of oxide-ion conductors. In the present work, we have investigated the crystal structure and electrical conductivity of Ba1+xNd1-xInO4-x/2 where x is the excess Ba content. It was found that Ba1.1Nd0.9InO3.95 shows (i) about 12 times higher oxide-ion conductivity at 858°C and (ii) a little lower activation energy for oxide-ion conduction than BaNdInO4. The higher oxide-ion conductivity of Ba1.1Nd0.9InO3.95 is mainly ascribed to higher carrier concentration. Careful structure analyses using both the single-crystal X-ray diffraction and time-of-flight (TOF) neutron powder diffraction data enabled to determine the position of excess Ba cation and occupancy factor of O anion. It was found that the excess Ba cation substitutes for Nd cation and that oxygen vacancies exist in Ba1.1Nd0.9InO3.95. The refined occupancy factor of oxygen atom 0.9829(17) indicates the higher concentration of oxygen vacancies in Ba1.1Nd0.9InO3.95, compared with BaNdInO4, giving higher oxide-ion conductivity in Ba1.1Nd0.9InO3.95. The larger-sized Ba substitution for Nd cation makes the bottleneck size larger, leading to the lower activation energy. The bond valence-based energy landscape calculated for the refined crystal structure of Ba1.1Nd0.9InO3.95 at 800 and 24°C indicated two-dimensional oxide-ion diffusion in the A rare earth oxide (Nd,Ba)2O3 unit on the bc plane. [ABSTRACT FROM AUTHOR]

A novel oxynitride, BaYSi2O5N, has been synthesized by a solid-state reaction method. Its crystal structure was determined by single-crystal X-ray analysis. Eu2+- and Ce3+-doped BaYSi2O5N exhibit broad blue emission with peaks around 459 and 412 nm under excitation at 250450 and 250370 nm, respectively. This is the first report on the synthesis of oxynitrides in the BaO-Y2O3-SiO2-Si3N4 system. [ABSTRACT FROM AUTHOR]

We determined the crystal structure of Ba2CoSi2O6Cl2, which was synthesized in this work, and investigated its quantum magnetic properties using single crystals. This compound should be described as a two-dimensionally coupled spin-1/2 XY-like spin dimer system. Ba2CoSi2O6Cl2 exhibits a stepwise magnetization process with a plateau at half of the saturation magnetization, irrespective of the field direction, although all the Co2+ sites are equivalent. This indicates that spin triplets are localized owing to the almost perfect frustration of interdimer exchange interactions. Thus, the spin states for the zero and 1/2 magnetization-plateau states are almost exactly given by the simple product of singlet dimers and the alternate product of singlet and triplet dimers, respectively. [ABSTRACT FROM AUTHOR]

We determined the crystal structure of Ba2CoSi2O6Cl2, which was synthesized in this work, and investigated its quantum magnetic properties using single crystals. This compound should be described as a two-dimensionally coupled spin-½ XY-like spin dimer system. Ba2CoSi2O6Ci2 exhibits a stepwise magnetization process with a plateau at half of the saturation magnetization, irrespective of the field direction, although all the Co2+ sites are equivalent. This indicates that spin triplets are localized owing to the almost perfect frustration of interdimer exchange interactions. Thus, the spin states for the zero and ½ magnetization-plateau states are almost exactly given by the simple product of singlet dimers and the alternate product of singlet and triplet dimers, respectively. [ABSTRACT FROM AUTHOR]

The structural properties of a new polymorph of a material distributed commercially as “hexaketocyclohexane octahydrate” have been determined directly from powder X-ray diffraction data, employing the direct-space genetic algorithm technique for structure solution followed by Rietveld refinement. It is shown that the molecule actually present in the crystal structure is dodecahydroxycyclohexane (C6(OH)12) rather than hexaketocyclohexane (C6O6). This assignment is also confirmed from high-resolution solid-state 13C NMR data. The crystal structure contains two molecules of water per molecule of C6(OH)12. In the asymmetric unit, there are 16 hydrogen-bond donor groups (O–H bonds) and 14 hydrogen-bond acceptors (oxygen atoms), leading to multiple permutations for intermolecular hydrogen-bonding arrangements. Detailed analysis of the results from Rietveld refinement suggests that a disordered model provides the most appropriate description of the hydrogen-bonding arrangement, in which the hydrogen atom of each OH group of C6(OH)12and the hydrogen atoms of each water molecule are distributed among several different intermolecular O–H···O hydrogen bonds. The density of this material (1.926 g cm–3at ambient temperature) is one of the highest ever reported densities among organic materials that contain no elements heavier than oxygen. [ABSTRACT FROM AUTHOR]

5-Aminoisophthalic acid (AIPA) was found to undergo reversible color change on exposure to solvent vapors, which is called vapochromism, via pseudopolymorphic transformations between the pale-pink hemihydrate and the yellow anhydrous crystals. By exposing methanol, ethanol, or acetonitrile vapor on the hemihydrate crystal, the hemihydrate crystal transformed into a novel anhydrous crystal and the anhydrous crystal returned into the hemihydrate crystal under the existence of water vapor. X-ray structural analysis revealed that the AIPA molecule is in a zwitterionic form in the hemihydrate crystal whereas it is in a nonionic form in the anhydrous phase. Theoretical calculations revealed that the isomerization between nonionic and zwitterionic forms causes a solid-state color difference. [ABSTRACT FROM AUTHOR]

A new anhydrous chiral phase of Ru(bipy)3(ClO4)2(bipy = 2,2′-bipyridine) has been prepared both by mechanical grinding followed by annealing of the known chiral hydrate phase of this material and by solid-state dehydration of the chiral hydrate phase at high temperature. The new phase is obtained from these processes as a microcrystalline powder, thus limiting the opportunity to carry out structural characterization by single-crystal X-ray diffraction. Instead, our structure determination of the new chiral anhydrous phase has exploited the capabilities of modern powder X-ray diffraction techniques, employing the direct-space genetic algorithm technique for structure solution followed by Rietveld refinement. The structural properties of the chiral anhydrous phase are discussed, particularly with regard to assessing the structural relationship to the parent hydrate phase. [ABSTRACT FROM AUTHOR]

The crystalline state of 2-(2,4,6-triisopropybenzoyl)((S)-1-phenylethyl)benzamide (1) is known to undergo a diastereospecific Norrish type II photocyclization under UV irradiation, giving a single photoproduct (R,S)-cyclobutenol (2). Its polycrystalline form (2A) has a different X-ray diffraction pattern from the known polymorph 2B, which is obtained from recrystallization of the photoproduct. Such a polymorphic phenomenon, which is the result of a solid-state photoreaction, is, in itself, highly interesting and the structure of the photoproduct 2Ashould directly lead to the photoreaction mechanism. Thus, the crystal structure of 2Ahas been directly determined from the powder X-ray diffraction data. Interestingly, the crystal packing has been retained during the photoreaction process and, although the powder X-ray diffraction pattern is significantly different, there are only minor structural changes. The comparison of the crystal structures of 1and 2Areveals the photoreaction mechanism. The lattice energy calculations of the polymorphic forms of 2Aand 2Breveals that 2A, which is obtained only by the solid-state photoreaction, is less stable than 2B, which is why it is not reformed on recrystallization. [ABSTRACT FROM AUTHOR]

A new co-crystal (phase H) of 5-methyl-2-pyridone (5MP) and trimesic acid (TMA) has been prepared by grinding a methanol solvate co-crystal (phase M) of 5MPand TMAunder ambient conditions. Powder X-ray diffraction indicates that the new co-crystal phase His structurally different from the methanol solvate co-crystal (phase M) and an unsolvated co-crystal (phase U) of 5MPand TMAreported previously. In the present work, the crystal structure of the new phase Hhas been determined directly from powder X-ray diffraction data, allowing insights to be gained regarding the mechanism of the transformation from Mto H. The structural analysis reveals that phase His a hydrate of 5MPand TMA, and thus the transformation from Mto His a solvent exchange process. The rate of this process is shown to be accelerated significantly by grinding. Further vapour induced transformations have been investigated for phases M, H, and U, and insights regarding transformation mechanisms have been established from consideration of the crystal structures. [ABSTRACT FROM AUTHOR]

Crystal structures of two black monoazo (hydrazone) pigments have been determined from powder X-ray diffraction data combined with DFT calculations. The DFT calculations suggested the molecules are in hydrazone forms but not in azo forms in both crystal structures. The molecular arrangements in the crystal structures suggested Davydov splitting may occur by excitonic interactions and it causes the red absorption band shift in the crystalline state leading to the characteristic black colors. [ABSTRACT FROM AUTHOR]

The methanol solvate crystalline phase (M) of benzene-1,2,4,5-tetracarboxylic acid transforms selectively to a hydrate phase (H) or a non-solvate phase (N) depending on the presence of atmospheric water vapour; knowledge of the crystal structures of Mand N, determined here using single-crystal and powder X-ray diffraction, respectively, yields insights into mechanistic aspects of the solid-state transformations. [ABSTRACT FROM AUTHOR]

K2NiF4-type LaSrAlO4 and Sr2TiO4 exhibit anisotropic and isotropic thermal expansion, respectively; however, their structural origin is unknown. To address this unresolved issue, the crystal structure and thermal expansion of LaSrAlO4 and Sr2TiO4 have been investigated through high-temperature neutron and synchrotron X-ray powder diffraction experiments and ab initio electronic calculations. The thermal expansion coefficient (TEC) along the c-axis (αc) being higher than that along the a-axis (αa) of LaSrAlO4 [αc = 1.882(4)αa] is mainly ascribed to the TEC of the interatomic distance between Al and apical oxygen O2 α(Al--O2) being higher than that between Al and equatorial oxygen O1 α(Al--O1) [α(Al--O2) = 2.41(18)α(Al--O1)]. The higher α(Al--O2) is attributed to the Al--O2 bond being longer and weaker than the Al--O1 bond. Thus, the minimum electron density and bond valence of the Al--O2 bond are lower than those of the Al--O1 bond. For Sr2TiO4, the Ti--O2 interatomic distance, d(Ti--O2), is equal to that of Ti--O1, d(Ti--O1) [d(Ti--O2) = 1.0194(15)d(Ti--O1)], relative to LaSrAlO4 [d(Al--O2) = 1.0932(9)d(Al--O1)]. Therefore, the bond valence and minimum electron density of the Ti--O2 bond are nearly equal to those of the Ti--O1 bond, leading to isotropic thermal expansion of Sr2TiO4 than LaSrAlO4. These results indicate that the anisotropic thermal expansion of K2NiF4-type oxides, A2BO4, is strongly influenced by the anisotropy of B--O chemical bonds. The present study suggests that due to the higher ratio of interatomic distance d(B--O2)/d(B--O1) of A22.5+B3+O4 compared with A22+B4+O4, A22.5+B3+O4 compounds have higher α(B--O2), and A22+B4+O4 materials exhibit smaller α(B--O2), leading to the anisotropic thermal expansion of A22.5+B3+O4 and isotropic thermal expansion of A22+B4+O4. The "true" thermal expansion without the chemical expansion of A2BO4 is higher than that of ABO3 with a similar composition. [ABSTRACT FROM AUTHOR]