Daicel (Japan)

Understanding the mechanism of amyloid fibril formation, a nucleation-dependent process influenced by physicochemical conditions, is crucial for eradicating amyloidosis, as it represents the initial step in the pathological cascade of the disease. In this study, we develop a miniaturized ultrasonic platform for the amyloid fibril study, μHANABI, which enables reproducible and rapid analysis of amyloid formation kinetics. Leveraging the robustness of the developed system, we investigate the nucleation rate of α-synuclein, an intrinsically disordered protein, and β2-microglobulin, a natively folded protein, at various temperatures and salt concentrations. The lag time for nucleation exhibits a clear dependence on salt concentration: α-synuclein amyloid formation is monotonically accelerated with increasing salt concentration, whereas β2-microglobulin exhibits a U-shape dependence. This contrast can be rationalized by evaluating the degree of supersaturation as a function of temperature and salt concentration, linking the solubility-limited phase transition with the folding-related two-state transition. These results demonstrate the superior performance of μHANABI as an effective platform for physicochemical studies of amyloid formation mechanisms, and the obtained results provide a physicochemical understanding of amyloid nucleation coupled with the folding reaction.

The degradation behavior of adhesion between cycloaliphatic epoxy resin and copper under high temperature and high humidity conditions was investigated. The Cu/resin joints were aged at 175°C and at 85°C in 85% R. H. The degradation behavior of the joint interface was analyzed by tensile tests and Fourier infrared transform spectroscopy (FT-IR). As a result, it was confirmed that the adhesion strength was retained after aging at 175°C for 1000 h, while it decreased with an increase in the aging time by aging at 85°C in 85% R. H. Furthermore, the interfacial fracture mode increased with aging at 175°C. In contrast, cohesive fracture was the main fracture mode and hardly changed by aging at 85°C in 85% R. H. The FT-IR analysis results showed that the peak intensity of the carbonyl group increases and that of the methylene group decreases by aging at 175°C. The result indicates that the resin was oxidized. Moreover, the peak intensities of carboxy and hydroxyl groups increased and that of ester groups decreased by aging at 85°C in 85% R. H. The results suggest that ester groups may be hydrolyzed due to aging and thus the adhesion is degraded.

A thiuram disulfide-modified cellulose adsorbent (TDMC) was developed for the highly selective recovery of silver ions from aqueous solutions. The adsorbent was synthesized by introducing thiuram disulfide functional groups onto a cellulose backbone to selectively adsorb Ag(i). Batch adsorption experiments were conducted to evaluate the adsorption performance and selectivity under various conditions. The maximum adsorption capacity of TDMC for Ag(i), estimated from the Langmuir model, was 3.61 mmol g-1 at pH 1.0. Remarkably, TDMC exhibited outstanding selectivity toward Ag(i) even in the presence of high concentrations of competing metal ions. When Ag(i) coexisted with Cu(ii), Pb(ii), Zn(ii), Ni(ii), Ca(ii), K(i), Mg(ii), and Na(i) at 2000-fold higher total concentrations, the adsorption percentage of Ag(i) remained 99.0%, comparable to that under single-metal conditions, whereas those of other ions were below 2.5%. X-ray photoelectron spectroscopy revealed that adsorbed Ag atoms were bonded to sulfur atoms of the thiuram disulfide groups. Furthermore, fast atom bombardment mass spectrometry was performed on a low-molecular-weight thiuram-Ag(i) complex that exhibits spectroscopic features similar to those of Ag-TDMC, allowing us to determine the molecular weight and structural characteristics of the complex. These findings demonstrate that TDMC possesses an exceptional ability to selectively capture Ag(i) through specific Ag-S coordination, providing a simple and efficient approach for silver recovery.

プリント配線板の耐熱性向上，伝送損失低減を目的として，オリゴ（2,6-ジメチル-1,4-フェニレンエーテル）系樹脂に代わり，スルフィド結合によってベンゼン環が結合したポリ（2,6-ジメチル-1,4-フェニレンスルフィド）樹脂(PMPS-V)を用いたプリント配線板を作製し，その特性を評価した。PMPS-Vを配合したプリント配線板は，誘電正接が0.0017と低く，従来の難燃剤添加量の3分の1でUL94 V-0相当の難燃性を達成した。さらに，150°Cでの耐熱試験において60 GHzまでの信号伝搬特性を測定し，伝送損失およびアイダイアグラムの劣化抑制効果があることを見出した。

Fluorescent nanodiamonds (F-NDs) are promising materials for quantum applications, but their practical use is limited by difficulties in separating them from non-fluorescent nanodiamonds. We focus on optical manipulation as a sorting method for F-NDs and demonstrate a selection utilizing stimulated recoil force (SRF). SRF is a recoil force arising from stimulated emission that pulls particles in the direction opposite to light propagation. Compared to conventional resonant absorption force (RAF) that pushes particles in the light propagation direction, SRF enables more efficient separation by avoiding absorption saturation effects and generating larger optical forces. Using silicon-vacancy-containing NDs as a model system, we report that SRF-based sorting achieves significantly higher efficiency than RAF-based methods.

According to the literature, mainly in relation to mixed cellulose esters (MCEs) with two types of acyl group, the solubility parameter (SP) is a measure of certain physical properties of MCE that is helpful for property prediction; contrary to expectations, it has been implied by different studies that simple cellulose esters (SCEs) with only one type of acyl group do not altogether follow the empirical relationship. In this study, MCE and SCE were systematically prepared to verify the SP-property relationship. It was revealed that the correlation between SP and physical properties exists only for MCE. Thermal analysis revealed that MCEs possess remarkable unidentified endothermic transition depending on the ratio of two acyl groups, suggesting that the formation of such a stable structure could contribute to the difference between MCE and SCE. It was also revealed that, even for MCE, the empirical relationship involving SP varies from acyl group to acyl group; there is no universal relationship. In spite of aforementioned limitation, the empirical relationship with SP was verified to be useful for the property prediction of MCE. We demonstrated that the Fox equation and Voigt model are also useful for this prediction.

Optical manipulation of nanomaterials using light resonant with material excitations holds promise for enhancing optical forces and sorting particles by unique quantum properties. Conventional resonant optical sorting mainly relies on absorption and scattering forces, making it difficult to sort nanomaterials by specific emission lines. Furthermore, emission typically induces negligible force unless the material is highly anisotropic, limiting selective manipulation via emission characteristics. To address this, we propose optical sorting of targeted emission lines by harnessing recoil forces under an inverted-occupation condition. Our theoretical evaluation of nanodiamonds (NDs) with a single-color center demonstrates the feasibility of sorting them by color-center-specific emission. These findings provide a pathway for ultrahigh concentrations of detonation NDs with single-color centers, opening avenues for advanced quantum technology and biosensing.

To reduce transmission loss in printed wiring boards (PWBs), materials with low dielectric loss tangent, such as oligo(2,6-dimethyl-1,4-phenylene ether)-based resins, are commonly used. In this study, we fabricated PWBs blending poly(2,6-dimethyl-1,4-phenylene sulfide)-based resins (PMPS-V), in which benzene rings are connected via sulfide rather than ether bonds, and evaluated its effects. The PWBs exhibited a low loss tangent of 0.0017 and achieved UL94 V-0 flame retardancy with only one-third the conventional flame retardant content. Transmission loss and eye diagram degradation up to 30 GHz were effectively suppressed after heat testing at 150 °C. It was clarified that PMPS-V contributes to improving the thermal reliability of PWBs.