Nanodomain manipulation for ultrahigh density ferroelectric data storage

Nanosized inverted domain dots in ferroelectric materials have potential application in ultrahigh density rewritable data storage systems. Herein, a data storage system is presented based on scanning non-linear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, we succeeded in forming our smallest artificial nanodomain single dot at 5.1?nm diameter and an artificial nanodomain dot array with a memory density of 10.1?Tbit?inch(-2) and a bit spacing of 8.0?nm, representing the highest memory density for rewritable data storage reported to date. Subnanosecond (500?ps) domain switching speed has also been achieved. Next, actual information storage with a low bit error and high memory density was performed. A bit error ratio of less than 1 × 10(-4) was achieved at an areal density of 258?Gbit?inch(-2). Moreover, actual information storage is demonstrated at a density of 1?Tbit?inch(-2).     

Cryogenic delamination growth in woven glass/epoxy composite laminates under mixed-mode I/II fatigue loading

This paper investigates the fatigue delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates under mixed-mode I/II conditions at cryogenic temperatures. Fatigue delamination tests were performed with the mixed-mode bending (MMB) test apparatus at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K), in order to obtain the delamination growth rate as a function of the range of the energy release rate, and the dependence of the delamination growth behavior on the temperature and the mixed-mode ratio of mode I and mode II was examined. The energy release rate was evaluated using three-dimensional finite element analysis. The fractographic examinations by scanning electron microscopy (SEM) were also carried out to assess the mixed-mode fatigue delamination growth mechanisms in the woven GFRP laminates at cryogenic temperatures.     

Degradation Mechanism and Stability Improvement Strategy for an Organic Laser Gain Material 4,4′‐Bis[(N‐carbazole)styryl]biphenyl (BSBCz)

The organic material 4,4′‐bis[(N‐carbazole)styryl]biphenyl (BSBCz) is an excellent gain medium for laser devices. However, BSBCz laser output quickly degrades during photoexcitation, which is an issue that must be overcome before it can be used for practical applications. In this study, the photodegradation mechanisms of BSBCz are investigated with the aim of enhancing its excited‐state stability. The photodegradation of BSBCz is attributed to instability of the triplet excited states that would occasionally decompose into other species. This decomposition reduces absorption and introduces exciton quenchers. Incorporating the triplet managing material 9,10‐di(naphtha‐2‐yl)anthracene (ADN) into BSBCz films greatly improves photoluminescence and amplified spontaneous emission stability because of the effective removal of the unstable triplets by ADN. This triplet managing method makes it possible to increase operational stability for BSBCz‐based organic light‐emitting diodes. Therefore, these results will contribute toward the fabrication of stable optically and electrically pumped organic laser diodes.     

Production and characterization of recombinant tachycitin, the Cys-rich chitin-binding protein

Tachycitin is an invertebrate chitin-binding protein with anamidated C-terminus, and possesses antimicrobial activity againstboth fungi and bacteria. The ¹H-NMR-based tertiary structureof tachycitin was recently determined [Suetake et al. (2000)J. Biol. Chem., 275, 17929–17932]. In order to examinethe structural and functional features of tachycitin more closely,we performed for the first time, gene expression, refolding,¹⁵N-NMR-based characterizations, and antimicrobial activitymeasurements of a recombinant tachycitin (rTcn) that does nothave the amide group at the C-terminus. The NMR analysis indicatedthat rTcn possesses the same structural construction as thenative tachycitin. The backbone ¹⁵N relaxation measurementsshowed that the molecular motional correlation time of rTcnincreases as its concentration increases, indicating that tachycitinshave a tendency to aggregate with each other. rTcn exhibitsantimicrobial activity against fungi but not against bacteria.The cell surface of fungi contains chitin as an essential constituent,but that of bacteria does not. These results suggest that notonly the chitin-binding region but also the C-terminal amidegroup of tachycitin plays a significant role in its antimicrobialproperties.     

Cationic Copolymer‐Chaperoned 2D–3D Reversible Conversion of Lipid Membranes

Nanosheets have thicknesses on the order of nanometers and planar dimensions in the micrometer range. Nanomaterials that are capable of converting reversibly between 2D nanosheets and 3D structures in response to specific triggers can enable construction of nanodevices. Supra‐molecular lipid nanosheets and their triggered conversions to 3D structures including vesicles and cups are reported. They are produced from lipid vesicles upon addition of amphiphilic peptides and cationic copolymers that act as peptide chaperones. By regulation of the chaperoning activity of the copolymer, 2D to 3D conversions are reversibly triggered, allowing tuning of lipid bilayer structures and functionalities.     

Purification and characterization of an alkaline manganese peroxidase from Aspergillus terreus LD-1

We report that Aspergillus terreus LD-1 produces an extracellular ligninolytic enzyme, manganese peroxidase (MnP), that reacts under alkaline conditions. This MnP was purified 13.1-fold from the culture supernatant to elicit a single band upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of this MnP was estimated as either 43 kDa by SDS-PAGE or 44 kDa by gel permeation chromatography, suggesting a monomeric structure. The optimum pH and temperature of this MnP are 12.5 and 37 degrees C, respectively. This MnP is stable in the pH range 11.0 to 12.5 and also up to 40 degrees C. The K(m) values of this MnP for hydrogen peroxide, 2,6-dimethoxyphenol (2,6-DMP) and Mn2+ were 320 microM, 20 microM and 33 microM at pH 12.5, respectively. The activity of the MnP is completely inhibited by Hg2+, Pb2+, Ag+ and lactate. On the other hand, the MnP is activated by oxalate, maleate and fumarate. Maleate at 5 mM increased the MnP activity 5-fold. EDTA at 1 mM inhibited the MnP activity completely, but this inhibition was not observed in the presence of 1 mM Fe2+.     

Regio‐ and Stereoselective Synthesis of Tri‐ and Tetrasubstituted Enamides via Palladium‐Catalyzed Silaboration of Ynamides

The palladium‐catalyzed silaboration of ynamides is demonstrated. The silaboration proceeds in a highly regioselective manner to give the corresponding tri‐ and tetrasubstituted enamide derivatives having both a silyl group and a boryl group on the alkene. Furthermore, the silaborated enamide could be utilized as a coupling partner in Suzuki–Miyaura coupling with aryl iodides to give the corresponding cross‐coupling product in good yield.     

Origin and control of high-temperature ferromagnetism in semiconductors

The extensive experimental and computational search for multifunctional materials has resulted in the development of semiconductor and oxide systems, such as (Ga,Mn)N, (Zn,Cr)Te and HfO(2), which exhibit surprisingly stable ferromagnetic signatures despite having a small or nominally zero concentration of magnetic elements. Here, we show that the ferromagnetism of (Zn,Cr)Te, and the associated magnetooptical and magnetotransport functionalities, are dominated by the formation of Cr-rich (Zn,Cr)Te metallic nanocrystals embedded in the Cr-poor (Zn,Cr)Te matrix. Importantly, the formation of these nanocrystals can be controlled by manipulating the charge state of the Cr ions during the epitaxy. The findings provide insight into the origin of ferromagnetism in a broad range of semiconductors and oxides, and indicate possible functionalities of these composite systems. Furthermore, they demonstrate a bottom-up method for self-organized nanostructure fabrication that is applicable to any system in which the charge state of a constituent depends on the Fermi-level position in the host semiconductor.     

Quantitative measurement of physisorbed silane on a silica particle surface treated with silane coupling agents by thermogravimetric analysis

We investigated a new method for estimating the amount of silanes physisorbed on a silica particle surface treated with silane coupling agents from a weight loss curve measured by thermogravimetric (TG) analysis. The silica particles were treated with 3‐glycidoxypropyl trimethoxysilane (GPTMS) or 3‐mercaptopropyl trimethoxysilane (MrPTMS) with both dry and wet treatment methods. In the TG curve for silica particles treated with GPTMS, the weight decreased in three steps: 100–170°C (first step), 170–250°C (second step), and 250–400°C (third step). The weight loss in the first step decreased with heating or acetone washing to remove the physisorbed molecules as the posttreatment. The three weight losses were found to be based on physisorbed monomeric silanes (first step), physisorbed polycondensed silanes (second step), and chemisorbed silanes (third step), respectively. The amount of physisorbed silanes on the silane‐treated layer could be estimated from the TG curve without solvent washing to remove the physisorbed molecules. The amounts obtained were almost equal to those measured from a comparison of the weight losses for the treated particles before and after acetone washing. A similar tendency was observed for MrPTMS‐treated silica. Thus, the amount of physisorbed silanes in silane‐coupling‐agent‐treated silica particles was successfully estimated from the TG measurements. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43256.