Biominerals are inorganic/organic composites formed in living organisms. They have significant optical properties and mechanical toughness based on their hierarchical structures. Material scientists can design highly functional inorganic/organic hybrid materials inspired by biomineralization. Here we review recent studies about the formation of thin-film inorganic/organic hybrids. The novel composite materials with regular patterned surfaces or macroscopical orientation were demonstrated by using organic polymeric templates.

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Antifreeze proteins (AFP) and glycoproteins (AFGP) help fish, plants, insects and bacteria survive sub-freezing environments. It is well known that these proteins function via some surface interaction, but the exact mechanism has eluded scientists. Aside from mutagenesis experiments directed towards examining the functional importance of specific residues, conclusions about the mechanism have been drawn from indirect studies or more precisely from studies that describe the proteins effects on the ice interface. Here, we will review recent work aimed at directly studying the protein kinetics at the ice interface. fluorescent microscopy is used to determine interaction planes, surface concentrations as well as adsorption characteristics, while fourier transform infra-red attenuated total reflectance (FTIR-ATR) is used to determine the protein structure vs. temperature in the liquid and solid states as well as the ice interface characteristics. Although the functions to some degree are the same, it becomes somewhat evident that the AFGP, AFP III, and spruce budworm AFP (sbwAFP) kinetics at the ice/solution interface, as well as the mechanism, can be rather different.

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This article describes recent studies of ice growth inhibition by antifreeze protein, which is an example of crystal growth influenced by large impurity molecules. A recent molecular dynamics simulation study successfully provided knowledge on the binding structure of antifreeze protein to a growing ice interface and the molecular-scale growth kinetics of ice around the protein, which largely contributed to understanding of the growth inhibition mechanism of ice by antifreeze protein. However, many points concerning the growth inhibition mechanism still remain unclear. Future studies about ice growth inhibition by antifreeze protein and related topics will also be discussed.

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There are many factors that affect the quality of grown protein crystals. Most of the discussions on this subject look for external causes, such as the presence of impurities in the solution or disturbances in its temperature or concentration. But even under identical crystallization conditions, slight differences in the properties of protein molecules can cause dramatic changes in the quality of final crystal. Proteins into which point mutations have been introduced provide a good example-there are some cases where crystals do not form from wild-type molecules but single crystals can easily be obtained from mutants. This phenomenon means that the quality of grown crystal varies according to the physical properties of the molecules themselves; i.e., according to internal factors. Based on an analysis of intermolecular interactions, this study investigates how the substitution of a single amino-acid residue affects the quality of grown crystal, and how this factor is related to changes in the inherent physical properties of the protein molecules, taking the Ynd1p protein as an example.

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Although various kinds of additives have been added to the amorphous region of polymer materials to improve their performance, few attempts have been done to incorporate functional organic molecules into the crystalline region. Recently, it has been clarified that syndiotactic polystyrene (sPS), which is a well-known stereoregular polymer and used as a commodity polymer, forms crystalline-region based composite materials with many kinds of organic molecules. A procedure based on the guest exchange phenomenon expands the range of applicable molecules as guest. In particular, the addition of a plasticizer to the target guest compound remarkably facilitates the complex formation of sPS. We have followed the guest exchange process of sPS with FTIR-ATR spectroscopy, which gives us plenty of information about not only the behavior of old and new guest molecules and plasticizer but also the structural change of host sPS framework.

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We developed a method for simulating the birefringence of an annealed ingot of MgF_2 single crystal caused by the residual stress after annealing process. The method comprises the heat conduction analysis that provides the temperature distribution in the ingot during annealing, the elastic thermal stress analysis using the assumption of the stress-free temperature that provides the residual stress after annealing, and the analysis of the birefringence of an annealed ingot induced by the residual stress. The finite element method was applied to the heat conduction analysis and the elastic thermal stress analysis. In these analyses, the temperature dependence of material properties and the crystal anisotropy were taken into account. In the birefringence analysis, we proved the equivalence of the Jones calculus and the average stress method. Then we calculated the optical path difference induced by residual stress, using the average stress method. In these analyses, we obtained the distributions of optical path difference with the symmetry of the crystal and the intrinsic birefringence caused by it.

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