Material-binding peptide application--ZnO crystal structure control by means of a ZnO-binding peptide

Recently, a zinc oxide (ZnO)-binding peptide (ZnOBP) has been identified and has been used to assist the synthesis of unique crystalline ZnO particles. We analyzed the influence of ZnOBP on the crystal growth of ZnO structures formed from zinc hydroxide. The addition of ZnOBP in the hydrothermal synthesis of ZnO suppressed [0001] crystal growth in the ZnO particles, indicating that the specificity of the material-binding peptide for specific inorganic crystal faces controlled the crystal growth. Furthermore, the dipeptides with a partial sequence of ZnO-binding "hot spot" in ZnOBP were used to synthesize ZnO particles, and we found that the presence of these dipeptides more strictly suppressed (0001) growth in ZnO crystals than did the complete ZnOBP sequence. These results demonstrate the applicability of dipeptides selected from material-binding peptides to control inorganic crystal growth.     

Designing novel multiconstituent inter me tallies: Contribution of modern alloy theory in developing engineered materials

This paper shows how materials scientists and engineers can take advantage of the knowledge generated by modern alloy theory for the development of real structural intermetallics and what further contribution is expected from theoretical scientists. In the first part of this paper, the importance of developing multiphase materials, in particular, based on the outstanding mechanical performance of Ni-base superalloys is emphasized first. Inspired by the two-phase γ- γ’ microstructure, which constitutes key factor for their mechanical performance, the authors have tried to generate two-phase γ- γ’ type microstructures in different alloy systems. The outcome of this effort is illustrated by some successful examples such as Fe-Ni₂AlTi and Ta-(Ti,Zr)₂Al(Mo,Nb). The second part of this paper deals with complex B2 aluminides of refractory metals. These aluminides are constituted by three groups of metallic elements, namely X = (Ti, Zr, Hf), Al and Y = (V, Nb, Ta, Cr, Mo, W),and their field of existence in the pseudoternary X-Al-Y system is often very large. It is found that there is a large variety of ordered states for these aluminides; in particular, their degree of order varies from one alloy composition to another. The last part of this paper describes the mechanical behavior of several alloys of the X-Al-Y system, characterized by an unusually high room-temperature tensile ductility (10 to 28 %). Plastic instabilities encountered during high-temperature extrusion are also mentioned. Such instabilities, characterized by a “van Gogh’s sky”-like microstructure, originate from local variations in deformability or hardness presumably caused by the variation of the degree of order associated with a change of the local chemistry due to preexisting dendritic segregation.     

Phase Reactions and Diffusion Path of the SiC/Cr System

Solid-state bonding at pressureless-sintered SiC has been carried out using 25-m Cr foil at temperatures from 1373 to 1773 K for 1.8 ks in vacuum. The formation of reaction phases and microstructures at the interface between SiC and Cr was investigated by X-ray diffraction and microprobe analysis. At the bonding temperature of 1373 K the cubic Cr₂₃C₆phase formed next to Cr, and the hexagonal Cr₇C₃ phase formed next to SiC. At 1473 K the cubic phase Cr₃SiC_x appeared additionally on the SiC side. At 1573 K the complete diffusion path was established. Upon increasing the joining temperature beyond 1573 K all the chromium was consumed, and Cr₂₃C₆ and Cr₃SiC _x dissolved. A layered structure consisting of SiC/Cr₅Si₃ C _x /Cr₇C₃/Cr₅Si₃ C _x /SiC occurred.     

The effect of Si upon the interfacial reaction characteristics in SiCp/Al-Si system composites during multiple-remelting

The composite interfaces play an important role in determining the resultant composite properties, especially the development of interfacial reaction during remelting is critical to the commercialization and sustainable-development of metal matrix composites. In this paper, the interfacial reaction characteristics of SiCp/Al-Si system composites during multiple-remelting were investigated by Differential Scanning Calorimeter (DSC). It was found that the interfacial reactions were not sensitive to remelting number, remelting temperature and reinforcement volume fraction after a degree of reaction, and the results also suggested that the preventation effects of Si upon the interfacial reaction SiCp/Al were mainly attributed to the Si released from the interfacial reaction, while the original Si content in the master alloy also has the same effect only after a given Si content.     

Synthesis of Amorphous Boron Nitride by Pressure Pyrolysis of Borazine

Amorphous BN that contains hydrogen could be synthesized by pressure pyrolysis of borazine below 700°C at 100 MPa. The fraction of B and N bonded to H in the pyrolysis product could be controlled by changing the pressure pyrolysis condition. The pyrolysis product at 700°C and 100 MPa showed formation of B-N-B bonds of the hexagonal structure in the amorphous state with some B-H and N-H bonding remaining. Spherulitic BN could be prepared only by pyrolysis below 400°C and 100 MPa. The yield of amorphous BN from borazine was as high as about 60% by this pressure pyrolysis. Amorphous BN formed from borazine could be readily converted to cubic BN by reacting it with AIN at 1200°C and 6.5 GPa.     

The oxidation of nanocrystalline Ni3Al fabricated by mechanical alloying and spark plasma sintering

Nanocrystalline Ni₃Al was fabricated through mechanical alloying of elemental powders and spark plasma sintering. The nanocrystalline Ni₃Al has a nearly full density after being sintered at 1223 K for 10 min under a pressure of 65 MPa. Isothermal and cyclic oxidations of nanocrystalline Ni₃Al were tested at 1173–1373 K with intervals of 100 K. The results indicate that nanocrystalline Ni₃Al exhibits excellent isothermal and cyclical oxidation resistance. The oxide scales consist primarily of dense and continuous -Al₂O₃. The grain refinement is beneficial for improving the oxidation resistance of Ni₃Al by providing more nucleation centers for the Al₂O₃ formation, promoting the selective formation of Al₂O₃ and improving the adhesion of oxide scales to the matrix.     

Hydrothermal synthesis and in situ surface modification of boehmite nanoparticles in supercritical water

In situ surface modification of boehmite (AlOOH) nanoparticles during hydrothermal synthesis in supercritical water was examined by adding CH₃(CH₂)₄CHO and CH₃(CH₂)₅NH₂ as modifier reagents to the reactants. Changes in surface properties of the nanoparticles by surface modification was observed by FTIR, dispersion in solvents and TEM analyses, which demonstrated that reagents chemically binded onto the surface of the AlOOH nanoparticles. The results of SEM and TEM pictures show that the surface modification affects crystal growth and reduces the particle size and changes the morphology of the particles.     

Improvement of corrosion resistance of magnesium metal by rare earth elements

Mg metal containing rare earth metals (REs) can be electrowon directly by molten salt electrolysis. The clarification of the optimum RE content in Mg is necessary to fix the electrolytic conditions in the direct electrowinning of Mg with RE. From this point of view, effect of RE addition in Mg metal on its corrosion property was studied in detail in this study. The specimen was prepared by adding La, Nd, or Ce in melted Mg metal, and its corrosion resistance was examined by an immersion test in 3 mass%-NaCl solution at room temperature. The corrosion resistance of Mg was improved greatly by adding a small amount of RE, whereas the excess addition of RE deteriorated the corrosion resistance. The optimum RE content was about 0.5 mass%. In this study, the corrosion property of Mg with an artificial surface oxide layer was also studied to clarify the effect of surface oxide. The corrosion resistance of Mg was particularly strengthened by conversion coating in a solution including La(NO₃)₃, Nd(NO₃)₃, or Ce(NO₃)₃, with Mg(NO₃)₂. This result suggests that the surface oxide film consisting of both Mg and RE gives ideal corrosion resistance to Mg metal. Mg metal with conversion coating including RE should also be of use as a corrosion-resistant material.     

Transport of human immunoglobulin G and Fc-fusion proteins to chicken egg yolk

We examined the transport of human immunoglobulin G (IgG) subclasses and fusion proteins with the Fc region of human IgG to the egg yolk, after the proteins were injected into a vein of hens. Human IgGs were efficiently transported and accumulated into the yolk, whereas the proteins were not detected in the egg white. Among human IgG subclasses, IgG2 was transported most efficiently. Fc-fusion proteins injected were also transported into the yolk. A fusion protein with the Fc region derived from human IgG2 was more efficiently transported into the yolk than the counterpart fusion with the Fc region from human IgG1. This study shows that the recovery of recombinant antibodies and Fc-fusion proteins from the yolk is an effective method in transgenic chicken bioreactors.     

The Superconducting Ferromagnet UCoGe

The correlated metal UCoGe is a weak itinerant ferromagnet with a Curie temperature T _C=3 K and a superconductor with a transition temperature T _s=0.6 K. We review its basic thermal, magnetic—on the macro and microscopic scale—and transport properties, as well as the response to high pressure. The data unambiguously show that superconductivity and ferromagnetism coexist below T _s=0.6 K and are carried by the same 5f electrons. We present evidence that UCoGe is a p-wave superconductor and argue that superconductivity is mediated by critical ferromagnetic spin fluctuations.