X-ray diffractometry for the structure determination of a submicrometre single powder grain

A high-precision diffractometer with a synchrotron radiation microfocusing technique has been developed to investigate the crystal structure of a submicrometre-scale single grain of powder sample. The structure of a BaTiO3 single powder grain, of dimensions ∼600 × 600 × 300 nm, was determined

In situ Zn/ZnO mapping elucidating for “shape change” of zinc electrode

For the use of the zinc anode in secondary batteries, it is necessary to solve the “shape change” deterioration issue in that zinc species agglomerate in the center of the electrode to fade the available capacity. The local chemical compositions of the zinc electrodes during “shape change” were precisely analyzed using the synchrotron X-ray diffraction mapping analysis of practical zinc-nickel cells in a non-destructive manner. The in situ Zn/ZnO mapping shows that metallic Zn deposition chiefly occurs in the periphery of ZnO while ZnO are left in the center of electrode like a hill on charging. On discharging, the ZnO hill grows to the perpendicular direction on the electrode while metallic zinc is oxidized and dissolved. These findings allow us to propose a mechanism for the shape change; thus dissolved zincate species are decomposed on the ZnO hill during discharging to be accumulated in the center of the electrode. It is suggested that suppressing zincate dissolution and non-uniform zinc deposition slow the growth rate of the ZnO hill to enhance the cyclability of zinc-based secondary batteries

CD46 Transgenic Mouse Model of Necrotizing Fasciitis Caused by Streptococcus pyogenes Infection▿

We developed a human CD46-expressing transgenic (Tg) mouse model of subcutaneous (s.c.) infection into both hind footpads with clinically isolated 11 group A streptococcus (GAS) serotype M1 strains. When the severity levels of foot lesions at 72 h and the mortality rates by 336 h were compared after s.c. infection with 1 × 107 CFU of each GAS strain, the GAS472 strain, isolated from the blood of a patient suffering from streptococcal toxic shock syndrome (STSS), induced the highest severity levels and mortality rates. GAS472 led to a 100% mortality rate in CD46 Tg mice after only 168 h postinfection through the supervention of severe necrotizing fasciitis (NF) of the feet. In contrast, GAS472 led to a 10% mortality rate in non-Tg mice through the supervention of partial necrotizing cutaneous lesions of the feet. The footpad skin sections of CD46 Tg mice showed hemorrhaging and necrotic striated muscle layers in the dermis, along with the exfoliation of epidermis with intracellular edema until 48 h after s.c. infection with GAS472. Thereafter, the bacteria proliferated, reaching a 90-fold or 7-fold increase in the livers of CD46 Tg mice or non-Tg mice, respectively, for 24 h between 48 and 72 h after s.c. infection with GAS472. As a result, the infected CD46 Tg mice appeared to suffer severe liver injuries. These findings suggest that human CD46 enhanced the progression of NF in the feet and the exponential growth of bacteria in deep tissues, leading to death

Spectroscopic X‑ray Diffraction for Microfocus Inspection of Li-Ion Batteries

We developed spectroscopic X-ray diffraction (XRD) analysis to visualize electrochemical reactions occurring at various locations in Li-ion batteries (LIBs). Continuous irradiation with monochromatic X-rays in an energy region using a confocal setup provided a fixed observation position on the order of several tens of microns. Unlike three-dimensionally position sensitive XRD analyses, e.g., angle-scanning XRD and energy-dispersive XRD, this energy-scanning XRD analysis with angle-scanning of the monochromator instead of the detector-scanning has the advantage of profile resolution, position sensitivity, and time-resolution for mapping concentration gradients and diffusion of Li⁺ associated with the electrochemical properties of LIBs. The microscopic structural inhomogeneity in a sheet-like composite electrode of LiNi_1/3Co_1/3Mn_1/3O₂ with a thickness of 150 μm was successfully determined with a depth resolution of 50 μm during cell operation. This work demonstrates the potential of spectroscopic XRD as a nondestructive and pinpoint analysis method, thus contributing to the development of high-performance LIBs

Thickness estimation of interface films formed on Li_{1−x}CoO2 electrodes by hard X-ray photoelectron spectroscopy

Solid electrolyte interface (SEI) films formed on Li_{1−x}CoO_2 electrodes were observed with hard X-ray photoelectron spectroscopy (HX-PES). This paper particularly focuses on film thickness estimation using HX-PES with theoretical calculation. The validity of the calculation was proven by experiments using model SEI films. The native film formed on a LiCoO2 composite electrode was estimated to be LiF with its thickness of 5 nm. Formation of Co (II) species on top of LiCoO_2 was also indicated. Storage of the electrode at 60 °C brought about considerable film growth (30–40 nm) with carbonate compounds formation. SEI film changes during charging of the LiCoO_2 electrode were also examined. The main component in the film was deduced to be LiF or a kind of fluorite, with its thickness decreased during charging. The SEI formation mechanisms are also elucidated

Transient Phase Change in Two Phase Reaction between LiFePO₄ and FePO₄ under Battery Operation

Transient states of phase transition in LiFePO₄/FePO₄ for lithium ion battery positive electrodes are investigated by time-resolved measurements. To directly detect changes in electronic and crystal structures under battery operation, <i>in situ</i> time-resolved X-ray absorption and diffraction measurements are performed, respectively. The phase fraction change estimated by the iron valence change is similar to the electrochemically expected change. The transient change of lattice constant during two phase reaction is clearly observed by the time-resolved X-ray diffraction measurement. The nonequilibrium lithium extraction behavior deviates from the thermodynamic diagram of the two phase system, resulting in continuous phase transition during electrochemical reactions

Supramolecularly Engineered Perylene Bisimide Assemblies Exhibiting Thermal Transition from Columnar to Multilamellar Structures

Perylene 3,4:9,10-tetracarboxylic acid bisimide (PBI) was functionalized with ditopic cyanuric acid to organize it into complex columnar architectures through the formation of hydrogen-bonded supermacrocycles (rosette) by complexing with ditopic melamines possessing solubilizing alkoxyphenyl substituents. The aggregation study in solution using UV–vis and NMR spectroscopies showed the formation of extended aggregates through hydrogen-bonding and π–π stacking interactions. The cylindrical fibrillar nanostructures were visualized by microscopic techniques (AFM, TEM), and the formation of lyotropic mesophase was confirmed by polarized optical microscopy and SEM. X-ray diffraction study revealed that a well-defined hexagonal columnar (Col_h) structure was formed by solution-casting of fibrillar assemblies. All of these results are consistent with the formation of hydrogen-bonded PBI rosettes that spontaneously organize into the Col_h structure. Upon heating the Col_h structure in the bulk state, a structural transition to a highly ordered lamellar (Lam) structure was observed by variable-temperature X-ray diffraction, differential scanning calorimetry, and AFM studies. IR study showed that the rearrangement of the hydrogen-bonding motifs occurs during the structural transition. These results suggest that such a striking structural transition is aided by the reorganization in the lowest level of self-organization, i.e., the rearrangement of hydrogen-bonded motifs from rosette to linear tape. A remarkable increase in the transient photoconductivity was observed by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements upon converting the Col_h structure to the Lam structure. Transient absorption spectroscopy revealed that electron transfer from electron-donating alkoxyphenyl groups of melamine components to electron-deficient PBI moieties takes place, resulting in a higher probability of charge carrier generation in the Lam structure compared to the Col_h structure