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We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of Eu2+-activated Ca2SiO4 solid solution, the chemical formula of which is (Ca1.88Eu2+0.01□0.11)(Si0.78P0.22)O4, where □ denotes vacancies in Ca sites with the replacement of Si4+ by P5+. The emission spectrum upon the 335 nm excitation showed a relatively broad band centered at ca. 490 nm and a full width at half-maximum of ca. 80 nm. The crystal structure was made up of the four types of β-Ca2SiO4-like layers with one type of interlayer. The incommensurate modulation with superspace group Pnma(0 β 0)00 s was induced by the long-range stacking order of these layers. The modulation wavevector was 0.27404(2) × b*, with the basic unit-cell dimensions being a = 0.68355(2) nm, b = 0.54227(2) nm, and c = 0.93840(3) nm ( Z = 4). The basic structure contained two nonequivalent Ca sites. One site was fully occupied by Ca2+ and free from Eu2+ in the overall incommensurate structure. The occupational modulation at the other site was so significant that the sum of site occupation factors for Ca2+ and Eu2+ as low as 0.5 was seen at the interlayer. This site was too large for accommodation of Ca2+ but was suitable for Eu2+. Thus, the Eu2+ ions would exclusively concentrate at the relevant site, which would cause the emission peak of the incommensurate phase to be shifted to the shorter wavelength ranges as compared with those of the other commensurate phases such as β and α'L.

Cadmium (Cd) is an environmental contaminant that triggers toxic effects in various tissues such as the kidney, liver, and lung. Cd can also cause abnormal iron metabolism, leading to anemia. Iron homeostasis is regulated by intestinal absorption. However, whether Cd affects the iron absorption pathway is unclear. We aimed to elucidate the relationship between the intestinal iron transporter system and Cd-induced iron deficiency anemia. C57BL/6J female and male mice, 129/Sv female mice, and DBA/2 female mice were given a single oral dose of CdCl2 by gavage. After 3 or 24 h, Cd decreased serum iron concentrations and inhibited the expression of iron transport-related genes in the duodenum. In particular, Cd decreased the levels of divalent metal transporter 1 and ferroportin 1 in the duodenum. In addition, human colon carcinoma Caco-2 cells were treated with CdCl2. After 72 h, Cd decreased the expression of iron transport-related factors in Caco-2 cells with a pattern similar to that seen in the murine duodenum. These findings suggest that Cd inhibits iron absorption through direct suppression of iron transport in duodenal enterocytes and contributes to abnormal iron metabolism.

Grain-aligned polycrystalline lithium titanogallate, Li0.91Ti0.48Ga4.40O8 (LTGO), was successfully prepared by the combined techniques of reactive diffusion and ion exchange. We firstly synthesized the b-axis-oriented polycrystal of sodium titanogallate (NTGO) by the reactive diffusion between NaGaO2 and Ga2TiO5 at 1323 K for 24 h, followed by the ion-exchange reaction of Li+ for Na+ at 773 K for 125 h. The crystal structure of resulting LTGO (space group C2/m) was isomorphous with that of the original NTGO. Both crystal structures were built up of five types of polyhedra; [MO7] (M = Li or Na), [(Ti,Ga)O6], [Ga1O6], [Ga2AO4], and [Ga2BO6]. There was a marked difference between the two structures for the coordination environment of M; the centroid-to-M distance of [LiO7] (0.026 nm) was significantly larger than that of [NaO7] (0.008 nm). The lithium-ion conductivity along the b-axis steadily increased from 3.41 × 10− 4 to 6.21 × 10− 4 S cm− 1 with increasing temperature from 773 to 1073 K. The activation energy of conduction was 0.22 eV. The combination of the two distinct techniques would enable us to synthesize the grain-aligned polycrystalline materials with various constituent compounds and chemical compositions.

We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of Eu

A series of (Ca2-x/2-yEuy⿡x/2)(Si1-xPx)O4 (0 ⿤ x ⿤ 0.20 and 0.02 ⿤ y ⿤ 0.05) green-emitting phosphors were synthesized, and characterized by photoluminescence (PL) spectroscopy and X-ray powder diffraction. We compared the PL intensities between the phosphors that were annealed at 1373⿿1773 K and those of non-annealed ones. Actually, the (Ca1.95Eu0.02⿡0.03)(Si0.94P0.06)O4 phosphor, when annealed at 1473 K for 4 h, exhibited the highest PL intensity, which was 1.6 times higher than that of the non-annealed (Ca1.96Eu0.02⿡0.03)(Si0.96P0.04)O4 phosphor. The coexistence of the α⿿L- and β-phases would be essentially important for the enhancement of PL intensity and eventually provide a favorable environment for the efficient PL emission of Eu2+ ion. The disc-shaped sintered phosphor that was annealed at 1773 K clearly showed the core-shell structure, consisting of the red-emitting phosphor core and the green-emitting phosphor as shell. This unique structure in the annealed phosphor would be formed during the phase transitions.

The study of P-doped Ca2SiO4 (C2S) structure has demonstrated that the incorporation of P effectively stabilizes the high-temperature phases. In this work, we synthesize a series of (Ca2−x/2−yEuy□x/2) (Si1−xPx)O4 (0 ≤ x ≤ 0.20, 0.02 ≤ y ≤ 0.05) green-light emitting phosphors and discuss the influence of P concentration on the luminescence intensity and structural change of the host material. The phosphor is synthesized by a solid–state reaction and heated at 498 K for 6 h, and then at 1273 K for 8 h in air. Doping of Eu2+ is achieved by annealing the Eu2O3-containing materials at 1473 K for 3 h under a 90% N2–10% H2 reductive atmosphere. A phosphor with x = 0.04 and y = 0.03 shows the highest PL intensity, which is obviously higher than that of the P-free phosphor (x = 0) due to the structural change of the host material.

We synthesized the phosphors of RE3+-doped Li1+x (Ta1-zNbz)1-xTixO3 (LTNT) with various emission colors by solid-state reaction in air using a conventional electric furnace, where RE=Eu, Er, Tm, or Dy. The optimal host composition with each dopant was determined for the highest photoluminescence (PL) intensity; the relevant chemical formulas were Li1.11Ta0.89Ti0.11O3 (x=0.11 and z=0) with Eu3+, Li1.03 (Ta0.2Nb0.8)0.97Ti0.03O3 (x=0.03 and z=0.8) with Er3+, Li1.08 (Ta0.4Nb0.6)0.92Ti0.08O3 (x=0.08 and z=0.6) with Tm3+, and Li1.14 (Ta0.6Nb0.4)0.86Ti0.14O3 (x=0.14 and z=0.4) with Dy3+. The crystal structures of the phosphors were refined by the XRD-Rietveld method to clarify the relationship between the PL properties and crystal structures. In the LTNT host material, the most effective activator was the Eu3+ ion, with an internal quantum efficiency of 97%. The efficient PL emission is closely related to the coordination environment of Eu3+ in the [Li (Eu) O12] polyhedron of the host LTNT.

The disordered crystal structure of 20H-AlON (Al10O3N8) was determined by combined use of X-ray powder diffraction and transmission electron microscopy. The title compound is hexagonal with space group P63/mmc (Z=2) and the unit-cell dimensions are a=0.307082(5) nm, c=5.29447(8) nm and V=0.432376(12) nm3. The structural model showed the positional disordering of three of the six Al sites in the unit cell. The reliability indices calculated from the Rietveld method were Rwp=6.97%, S (=Rwp/Re)=1.68, Rp=5.45%, RB=5.13% and RF=4.56%. We interpreted the disordered structure of 20H-AlON as a statistical average of six different types of ordered structural configurations, which are composed of an octahedral [Al(O, N)6] layer and tetrahedral [Al(O, N)4] layers. We demonstrated the high correlations between the hexagonal unit-cell dimensions and the octahedral layer concentrations for AlON and SiAlON polytypoids.

The crystal structure of SiAl5O2N5was characterized by laboratory X-ray powder diffraction (CuKα1). The title compound is hexagonal with space groupP63/mmc(Z = 2). The unit-cell dimensions area = 0.303153(3) nm,c = 3.28153(3) nm, andV = 0.261178(5) nm3. The initial structural model was successfully derived by the direct methods and further refined by the Rietveld method. The final structural model showed the positional disordering of two of the four (Si,Al) sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF wereRwp = 5.00%,S(=Rwp/Re) = 1.25,Rp = 3.76%,RB = 1.26%, andRF = 0.90%. The disordered crystal structure was successfully described by overlapping four types of domains with ordered atom arrangements. The distribution of atomic positions in each of the domains can be achieved in the space groupP63mc. Two of the four types of domains are related by a pseudo-symmetry inversion, and the two remaining domains also have each other the inversion pseudo-symmetry.

The 8H-SiAlON crystal with general formula Si{sub 3−x}Al{sub 1+x}O{sub x}N{sub 5−x} was characterized using laboratory X-ray powder diffraction (CuKα{sub 1}), transmission electron microscopy and energy dispersive X-ray spectroscopy. The [Si: Al] molar ratios were determined to be [0.21(1): 0.79(1)], corresponding to x=2.2(1). The Si{sub 0.8(1)}Al{sub 3.2(1)}O{sub 2.2(1)}N{sub 2.8(1)} compound is hexagonal with space group P6{sub 3}/mmc (Z=2). The unit-cell dimensions are a=0.298877(8) nm, c=2.30872(5) nm and V=0.178602(8) nm{sup 3}. The initial structural model was successfully derived by the charge-flipping method and further refined by the Rietveld method. The final structural model showed the positional disordering of two of the three (Si,Al) sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R{sub wp}=4.74%, S (=R{sub wp}/R{sub e})=1.30, R{sub p}=3.40%, R{sub B}=1.04% and R{sub F}=0.74%. The disordered crystal structure was successfully described by overlapping four types of domains with ordered atom arrangements. The distribution of atomic positions in each of the domains can be achieved in the space group P6{sub 3}mc. Two of the four types of domains are related by a pseudo-symmetrymore » inversion, and the two remaining domains also have each other the inversion pseudo-symmetry. - Graphical abstract: Bird's eye view of electron densities up to 49.3% (0.071 nm{sup −3}) of the maximum on the plane parallel to (110) with the corresponding atomic arrangements of Si{sub 0.8}Al{sub 3.2}O{sub 2.2}N{sub 2.8}. - Highlights: • Crystal structure of Si{sub 0.8}Al{sub 3.2}O{sub 2.2}N{sub 2.8} is determined by laboratory X-ray powder diffraction. • The atom arrangements are represented by the split-atom model. • The maximum-entropy method-based pattern fitting method is used to confirm the validity of the model. • The disordered structure is described by overlapping four types of domains with ordered atom arrangements.« less

The crystal structure of Al9O3N7 was characterized by laboratory X-ray powder diffraction (CuKα1). The title compound is trigonal with space group R3m (centrosymmetric). The hexagonal unit-cell dimensions (Z=3) are a=0.30656(2) nm, c=7.2008(3) nm and V=0.58605(5) nm3. The initial structural model was derived by the powder charge-flipping method and subsequently refined by the Rietveld method. The final structural model showed the positional disordering of two of the five types of Al sites. The maximum-entropy method-based pattern fitting method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The disordered crystal structure was successfully described by overlapping five types of domains with ordered atom arrangements. The distribution of atomic positions in one of the five types of domains can be achieved in the space group R 3 ¯ m. The atom arrangements in the four other domains are noncentrosymmetric with the space group R3m. Two of the four types of domains are related by a pseudo-symmetry inversion, and the two remaining domains also have each other the inversion pseudo-symmetry. The very similar domain structure has been also reported for 21R-AlON (Al7O3N5) in our previous study.

The crystal structure of Al7O3N5was characterized by laboratory X-ray powder diffraction (CuKα1). The title compound is trigonal with a space groupR3m(centrosymmetric). The hexagonal unit-cell dimensions (Z = 3) area = 0.305 06(1) nm,c = 5.7216(1) nm, andV = 0.461 11(2) nm3. The initial structural model was derived by the charge-flipping method and refined by the Rietveld method. The final structural model showed the positional disordering of two of the four Al sites. The maximum-entropy method-based pattern fitting method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The disordered crystal structure was successfully described by overlapping five types of domains with ordered atom arrangements. The distribution of atomic positions in one of the five types of domains can be achieved in the space groupR3m. The atom arrangements in the four other domains are non-centrosymmetric with the space groupR3m. Two of the four types of domains are related by a pseudo-symmetrical inversion, and the two remaining domains also have each other in the inversion pseudo-symmetry.

Cilostazol, an antiplatelet drug, exhibits antiatherogenic effects. The purpose of the present study was to determine the effect of cilostazol on the cytotoxicity of cadmium (Cd) and arsenite (iAs(III)), which involved in the pathogenesis of vascular disorders such as atherosclerosis, in cultured vascular endothelial cells. Cytotoxicity was evaluated by the lactate dehydrogenase leakage assay and morphological observation. Cd (10 µM) -induced cytotoxicity was prevented by pretreatment with cilostazol (30 and 100 µM) and simultaneous treatment with cilostazol (100 µM). On the other hand, iAs(III)-induced cytotoxicity was blocked by pretreatment with cilostazol (30 and 100 µM) but not simultaneous treatment with cilostazol. The mRNA level and the protein level of metallothionein (MT) were significantly increased by cilostazol in the cells. These results suggested, therefore, that pretreatment with cilostazol effectively prevents the cytotoxicity of Cd and iAs(III) in cultured vascular endothelial cells, at least in part through the induction of MT synthesis.