本研究は，伝統的製法に基づき製造された古典的膠の構造的・物理的特性を科学的に検討したものである。研究対象は，90℃で3 時間，6時間，12時間加熱抽出した古典的膠と日本画制作で用いられる三千本膠である。分析には，円偏光二色性分光法によるタンパク質構造の評価，分光光度計による可視光透過率測定，振動式粘度計による粘度測定を用いた。その結果，加熱時間の延長により膠タンパク質中のランダムコイル構造が増加し，透明性の向上と粘度の低下が認められた。特に12 時間加熱抽出した膠は，三千本膠の約35 倍の可視光透過率を示し，同等以上の粘度の安定性を有していた。これらの知見は，加熱条件が日本画制作における膠の発色性，作業性，耐久性に大きく影響することを明らかにしている。本研究は，伝統素材の科学的再評価に寄与するとともに，文化財保存や材料科学への応用に資す，日本の文化的・技術的基盤の再構築を支援するものである。

In the automotive industry, adhesives that combine high bonding strength with easy disassembly have long been in demand. However, conventional adhesives̶including epoxy-based adhesives-offer strong adhesion but are difficult to dismantle, making them unsuitable for such applications. Here, we report a bio-based adhesive derived from β-（1,3）-glucan（paramylon）sourced from Euglena gracilis, which achieves a tensile shear strength of 30 MPa on aluminum substrates̶substantially higher than that of conventional bio-based adhesives. Remarkably, this adhesive also offers exceptional circularity: bonded components can be easily disassembled by simple heating, allowing manual separation, and the adhesive can be reused repeatedly by re-laminating and reheating the adherends, fully restoring its initial strength. This study represents the first demonstration of a bio-based adhesive that simultaneously fulfills the key requirements for automotive applications: high bonding strength, facile disassembly, and reliable reusability.

In recent years, it has become widely recognized that high-strength materials, such as high-strength steels and titanium alloys, can undergo fatigue failure originating from internal sites at stress levels lower than those expected from their static strength. This review introduces an evaluation methodology combining synchrotron radiation X-ray computed tomography（CT）and vacuum fatigue testing to clarify the mechanisms of internalinitiated fatigue fracture. The former technique enables the elucidation of the initiation and propagation behavior of small internal cracks, while the latter simulates the environment surrounding internal cracks that is not exposed to the atmosphere. The proposed approach was applied to two titanium alloys,（α+β）-type Ti–6Al–4V and β-type Ti–22V–4Al. The results demonstrate that, although both are classified as titanium alloys, the initiation sites, propagation paths, and growth rates of small internal cracks differ significantly between them. One of the primary factors responsible for these differences is considered to be the unique characteristics of internal cracks propagating in environments not exposed to air （i.e., high to ultra-high vacuum conditions）． Furthermore, the sensitivity of internal crack growth to vacuum environments may vary depending on the material, particularly in terms of adhesion and cohesive interactions at the crack tip and fracture surfaces. To properly evaluate internal-initiated fatigue fracture in metallic materials and to develop effective mitigation strategies, it is essential to incorporate interdisciplinary insights from adhesion and bonding science.