Multicrystalline Informatics Applied to Multicrystalline Silicon for Unraveling the Microscopic Root Cause of Dislocation Generation.

A comprehensive analysis of optical and photoluminescence images obtained from practical multicrystalline silicon wafers is conducted, utilizing various machine learning models for dislocation cluster region extraction, grain segmentation, and crystal orientation prediction. As a result, a realistic 3D model that includes the generation point of dislocation clusters is built. Finite element stress analysis on the 3D model coupled with crystal growth simulation reveals inhomogeneous and complex stress distribution and that dislocation clusters are frequently formed along the slip plane with the highest shear stress among twelve equivalents, concentrated along bending grain boundaries (GBs). Multiscale analysis of the extracted GBs near the generation point of dislocation clusters combined with ab initio calculations has shown that the dislocation generation due to the concentration of shear stress is caused by the nanofacet formation associated with GB bending. This mechanism cannot be captured by the Haasen-Alexander-Sumino model. Thus, this research method reveals the existence of a dislocation generation mechanism unique to the multicrystalline structure. Multicrystalline informatics linking experimental, theoretical, computational, and data science on multicrystalline materials at multiple scales is expected to contribute to the advancement of materials science by unraveling complex phenomena in various multicrystalline materials.

Sequence-controlled supramolecular terpolymerization directed by specific molecular recognitions.

Nature precisely manipulates primary monomer sequences in biopolymers. In synthetic polymer sequences, this precision has been limited because of the lack of polymerization techniques for conventional polymer synthesis. Engineering the primary monomer sequence of a polymer main chain represents a considerable challenge in polymer science. Here, we report the development of sequence-controlled supramolecular terpolymerization via a self-sorting behavior among three sets of monomers possessing mismatched host-guest pairs. Complementary biscalix[5]arene-C60, bisporphyrin-trinitrofluorenone (TNF), and Hamilton's bis(acetamidopyridinyl)isophthalamide-barbiturate hydrogen-bonding host-guest complexes are separately incorporated into heteroditopic monomers that then generate an ABC sequence-controlled supramolecular terpolymer. The polymeric nature of the supramolecular terpolymer is confirmed in both solution and solid states. Our synthetic methodology may pave an avenue for constructing polymers with tailored sequences that are associated with advanced functions.Nature can precisely control monomer sequences in biopolymers, but this is somewhat problematic in the formation of synthetic polymers. Here the authors show sequence-controlled supramolecular terpolymerization via self-sorting behavior among three sets of monomers possessing mismatched host-guest pairs.

Removal efficiency of water purifier and adsorbent for iodine, cesium, strontium, barium and zirconium in drinking water.

The severe incident of Fukushima Daiichi Nuclear Power Station has caused radioactive contamination of environment including drinking water. Radioactive iodine, cesium, strontium, barium and zirconium are hazardous fission products because of the high yield and/or relatively long half-life. In the present study, 4 pot-type water purifiers and several adsorbents were examined for the removal effects on these elements from drinking water. Iodide, iodate, cesium and barium were removed by all water purifiers with efficiencies about 85%, 40%, 75-90% and higher than 85%, respectively. These efficiencies lasted for 200 l, which is near the recommended limits for use of filter cartridges, without decay. Strontium was removed with initial efficiencies from 70% to 100%, but the efficiencies were slightly decreased by use. Zirconium was removed by two models, but hardly removed by the other models. Synthetic zeolite A4 efficiently removed cesium, strontium and barium, but had no effect on iodine and zirconium. Natural zeolite, mordenite, removed cesium with an efficiency as high as zeolite A4, but the removal efficiencies for strontium and barium were far less than those of zeolite A4. Activated carbon had little removal effects on these elements. In case of radioactive contamination of tap water, water purifiers may be available for convenient decontamination of drinking water in the home.

Cadmium sorption to plasma membrane isolated from barley roots is impeded by copper association onto membranes.

The present study was designed to examine the effect of copper (Cu) on sorption of cadmium (Cd) to plasma membrane (PM) preparations as one of the models of competition between metals on root PM. Plasma membrane preparations were obtained from roots of barley (Hordeum vulgare L. cv. Minorimugi) and 50 µM CdSO4 with or without 50 µM CuSO4 were added to the PM suspensions. The sorption of Cd to PM vesicles increased with time within 15 min while Cu sorption to the PM occurred instantaneously. The sorption of Cd to PM vesicles was inactivated immediately after the addition of Cu into the reaction mixture. Results indicate that Cu association to PM vesicles occurs quicker than Cd, and, as a result, impedes the access of Cd to PM vesicles. The present study suggests that the competition between Cd and other minerals at root PM of plants can be demonstrated by employing isolated PM preparations. We consider that the difference in the capacity among some minerals for impeding Cd sorption to PM may also be characterized by investigating the interaction between Cd and other minerals on the PM.

The function of filensin and phakinin in lens transparency.

PURPOSE: Beaded filaments are lens cell-specific intermediate filaments composed of two proteins: filensin and phakinin (CP49). Filensin and phakinin are believed to function in the maintenance of lens transparency. To elucidate the function of filensin and phakinin at the molecular level, we examined the degradation of these two proteins in normal and cataractous rat lenses. METHODS: A hereditary cataract model, the Shumiya cataract rat (SCR), was used for these studies. Anti-filensin antibodies were raised against three different regions of the protein, the rod domain, the inner region of the tail domain, and the outer region of the tail domain. Anti-filensin and anti-phakinin antibodies were used to examine the conformation of degradation of filensin and phakinin by western blot analysis and fluorescent immunocytochemistry of cryosectioned lenses. RESULTS: In the normal lens, filensin was processed from a 94 kDa protein to proteins of 50 kDa and 38 kDa. Similarly, phakinin was processed from a 49 kDa protein to one of 40 kDa. The concentrations of filensin and phakinin in the rat lens cortex fluctuated with age and decreased during cataractogenesis. The 50 kDa form of filensin decreased significantly before opacification. In the normal lens, phakinin, the filensin rod domain, and the filensin inner tail domain localized to membrane lining regions in the shallow cortex and to the central region of the cytoplasm in the deep cortex. The COOH-terminal domain of filensin localized to the membrane lining region in the deep cortex. In pre-cataractous lenses, phakinin and the filensin rod domain localized primarily to the membranes lining the shallow cortex region and were distributed throughout the cytoplasm of lens fiber cells in the deep cortex. CONCLUSIONS: The 50 kDa form of filensin is important for the localization of beaded filaments in lens fiber cells and for lens transparency.

Protein evolution by hypermutation and selection in the B cell line DT40.

Genome-wide mutations and selection within a population are the basis of natural evolution. A similar process occurs during antibody affinity maturation when immunoglobulin genes are hypermutated and only those B cells which express antibodies of improved antigen-binding specificity are expanded. Protein evolution might be simulated in cell culture, if transgene-specific hypermutation can be combined with the selection of cells carrying beneficial mutations. Here, we describe the optimization of a GFP transgene in the B cell line DT40 by hypermutation and iterative fluorescence activated cell sorting. Artificial evolution in DT40 offers unique advantages and may be easily adapted to other transgenes, if the selection for desirable mutations is feasible.