Poly(4‐vinylpyridine)‐supported cationic bis(cyclopentadienyl)zirconocene catalyst: Development of a new simple method to prepare polymer‐supported cationic zirconocene and its application to ethylene polymerization

Bis(cyclopentadienyl)zirconocene dimethyl (Cp₂ZrMe₂) combined with triphenylcarbenium tetrakis(pentafluorophenyl)borate ([Ph₃C][B(C₆F₅)₄]) was brought into contact with a suspension of 2% cross‐linked poly(4‐vinylpyridine) to give a new type of polymer‐supported cationic zirconocene catalyst. The resulting polymer‐supported catalyst system combined with Al(i‐Bu₃) showed markedly high activity for ethylene polymerization in even a non‐polar solvent like hexane at 25–60°C and [Al]/[Zr] molar ratio 40–200. By the analysis of Zr content of the hexane solution, it was found that no Zr was detected in the solution, i. e. no leaching of the cationic catalyst into the hexane medium. The catalytic activity was found to increase with an increase of polymerization temperature and showed the highest at [Al]/[Zr] = 100. The molecular weight, crystalline melting temperature, crystallinity, and bulk density of polyethylene formed were higher than those of the polymer obtained from the homogeneous system.     

Destabilization of cytochrome c by modified β-cyclodextrin

To clarify the effect of cyclodextrin (CD) on the stability of cytochrome c, the thermal denaturation of cytochrome c was measured by differential scanning calorimetry in aqueous solutions of β-CD modified with three substituents: methyl, acetyl, and 2-hydroxylpropyl groups. The midpoint temperature of thermal denaturation decreased with the addition of modified β-CDs, indicating that cytochrome c was destabilized. The destabilization effect of CD depended on the substituent and increased in the order of acetyl>methyl>2-hydroxypropyl. The estimated binding number and binding constant of the modified β-CDs for cytochrome c are 5.0 ± 1.0 and 10.3 ± 2.9 M^?1 for methyl-β-CD, 13.8 ± 3.6 and 4.7 ± 1.6 M^?1 for acetyl-β-CD, and 2.8 ± 0.9 and 7.0 ± 3.0 M^?1 for 2-hydroxypropyl-β-CD. The destabilization effect of acetyl-β-CD is the highest because many CD molecules interact with proteins by the inclusion effect of CD and the inhibition effect of the acetyl group on the hydrogen bond in the secondary structure. In contrast, the stabilization effect of 2-hydroxypropyl-β-CD is the smallest because the steric exclusion of the 2-hydroxypropyl group inhibits the binding of CD to cytochrome c as compared with the smaller structure of the methyl group. Dependency of the destabilization effect on the molar ratio of CD to cytochrome c suggests that the destabilization effect of CD is caused not only by the “direct” interaction of CD with proteins but also by the “indirect” interaction of CD which promotes the solvation of hydrophobic groups by altering the water structure as observed in urea.     

The effect of atmospheric plasma treatments on plastic scintillator for beta-ray measurement

A plastic scintillator (PS) can be used for beta-ray measurements using a liquid scintillation counter (LSC) without the necessity for a liquid scintillator when liquid samples of beta-emitters are placed on the PS. However, the measurement efficiency with the PS in this study was not high, especially in the case of tritium. With a sample of tritiated water, a long measurement time was necessary with a conventional LSC. However, the measurement efficiency was improved drastically by modifying the PS surface with atmospheric-pressure glow-plasma processing (the plasma method). A 2 Bq, 20 μL sample of tritiated water placed between two PS sheets was successfully measured within 2 min by an LSC. The measurement efficiency was same as that of using liquid scintillator: 48 ± 2 % for tritiated water. The measurement efficiency was initially increasing over time, and after almost 6 h, it plateaued and remained at a constant value for several weeks. Additionally, the measurement efficiency of the plasma-modified PS was identical when it was used soon after the treatment and after being properly stored for 1 week The results show that plasma-modified PS can be used stably after storage in a freezer or a deep freezer. The plasma method is advantageous because it produces little radioactive waste fluid. This paper presents these results and the results of an investigation of the surface of the plasma-modified PS under observation with an atomic force microscope, and the mechanism behind the high measurement efficiency is discussed.     

Factors Related to Continuation of Health Behaviours among Stroke Survivors

Purpose: This study investigated stroke survivors'' perspectives of health behaviours after stroke. We aimed to explore the actual process by which stroke survivors changed their health behaviours. Method: Semi-structured interviews were conducted with 40 people in a 1-year prospective study in the regional city of Chiba, Japan. Interviews covered views of health behaviours in order to explore why patients change their risk factors. Data were analysed using the principles of modified grounded theory. Results: Six categories related to practising health behaviours were identified: cause of stroke, antithetic thinking, awareness of the body, fear of disease progression, view of health, and psychological meaning of practise. Stroke survivors constructed a meaning of practise for each health behaviour. The recognition of previous lifestyle as cause of stroke, hope for recovery, and fear of future progression influenced health behaviours. Conclusions: The key finding of this study is that when cognitive behavioural therapy principles are enforced, an important aspect is that stroke survivors recognize the possibility that previous lifestyle was a cause of stroke and appreciate the necessity of preventing a new stroke.     

Near‐Infrared‐III‐Absorbing and ‐Emitting Dyes: Energy‐Gap Engineering of Expanded Porphyrinoids via Metallation

The synthesis of organometallic complexes of modified 26π‐conjugated hexaphyrins with absorption and emission capabilities in the third near‐infrared region (NIR‐III) is described. Symmetry alteration of the frontier molecular orbitals (MOs) of bis‐Pd^II and bis‐Pt^II complexes of hexaphyrin via N‐confusion modification led to substantial metal d_π–p_π interactions. This MO mixing, in turn, resulted in a significantly narrower HOMO–LUMO energy gap. A remarkable long‐wavelength shift of the lowest S₀→S₁ absorption beyond 1700 nm was achieved with the bis‐Pt^II complex, t ‐Pt₂‐3 . The emergence of photoacoustic (PA) signals maximized at 1700 nm makes t ‐Pt₂‐3 potentially useful as a NIR‐III PA contrast agent. The rigid bis‐Pd^II complexes, t ‐Pd₂‐3 and c ‐Pd₂‐3 , are rare examples of NIR emitters beyond 1500 nm. The current study provides new insight into the design of stable, expanded porphyrinic dyes possessing NIR‐III‐emissive and photoacoustic‐response capabilities.     

18π‐Electron Tautomeric Benziphthalocyanine: A Functional Near‐Infrared Dye with Tunable Aromaticity

Dihydroxybenziphthalocyanine 1 , with bulky aryloxy groups, has been synthesized and characterized by X‐ray crystallography, NMR and UV/Vis‐NIR spectroscopy, and theoretical calculations. Macrocycle 1 is the first example of an aromatic benziphthalocyanine with an 18π‐electron structure, and was found to exist as an equilibrium mixture of weakly aromatic and strongly aromatic tautomers. The aromaticity and near‐IR absorption can be controlled by chemical modification at the reactive resorcinol moiety and by variation of the solvent.     

Direct perfluoroalkylation of non-activated aromatic C-H bonds of phenols

A simple procedure for the perfluoroalkylation of the aromatic ring of phenols under mildly basic conditions is described. Treatment of a variety of phenols with perfluoroalkyl iodide in the presence of the radical initiator V-70L and Cs₂CO₃ provided the corresponding perfluoroalkylated products in moderate to good yields. Generally, the reaction proceeded smoothly at room temperature to yield regioselectively perfluoroalkylated products.     

Isotropic-nematic phase transition in a system of slightly flexible long thin rods

On the basis of Onsager's formalism, the isotropic-nematic phase transition in a system of slightly flexible long thin rods are studied theoretically. The phase diagram and some other physical quantities are calculated and the effects of flexibility are clarified. In particular, it is shown that with increasing flexibility of the rods, the transition density increases and the metastable region of each phase becomes wide.