Full configuration interaction calculations of the second hyperpolarizabilities of the H4 model compound: summation-over-states analysis and interplay with diradical characters

The second hyperpolarizability (γ) of the one-dimensional H(4) model compound has been calculated at the full configuration interaction level to describe its relationships with the diradical characters y(i) [the occupation numbers of the lowest unoccupied natural orbital (LUNO) + i] and the geometry. It is found that the system with intermediate y(0) ( = 0.527) and small y(1) ( = 0.178) exhibits the largest γ value [enhanced by a factor of 9 compared to that of a nearly closed-shell H(4) analog (y(0) = 0.099, y(1) = 0.029)], where both the outer H-H distances are slightly larger than the inner one. These results provide a molecular design guideline for enhancing and controlling the third-order nonlinear optical properties of singlet multiradical linear molecular systems such as multiradical organic aggregates, supermolecular systems, and extended metal atom chains.     

Expression of heme oxygenase-1 due to intracellular reactive oxygen species induced by ultrasound

The present study was undertaken to elucidate the mechanism by which ultrasound induces the expression of heme oxygenase-1 (HO-1). When human lymphoma U937 cells were exposed to a 1 MHz continuous wave for 1 min, HO-1 expression examined by real-time quantitative polymerase chain reaction and immunoblotting was observed at intensities above the cavitational threshold. No induction of HO-1 expression was observed in the cells exposed for 1 min to 42 degrees C, a temperature higher than that during sonication. When a potent antioxidant, N-acetyl-l-cysteine, was added to the culture medium before or after sonication, the induction was attenuated, indicating that reactive oxygen species (ROS) are involved. However, the addition of catalase did not affect the induction, and no HO-1 was observed on the addition of pre-sonicated medium, suggesting that hydrogen peroxide due to the recombination of hydroxyl radicals generated extracellularly was not involved. The addition of free radical scavengers, glutathion-monoethyl ester, dimethyl sulfoxide and D(-)-mannitol, suppressed the induction. A decrease in mitochondrial membrane potential and the generation of superoxide were also observed in the sonicated cells, suggesting that mitochondria were the source of intracellularly generated ROS. These results indicate that superoxide secondarily generated from damaged mitochondria, not hydroxyl radicals generated in medium directly by sonication, give rise to intracellular oxidative stress inducing HO-1 expression.     

Exciton recurrence motion in aggregate systems in the presence of quantized optical fields

The exciton dynamics of model aggregate systems, dimer, trimer, and pentamer, composed of two-state monomers is computationally investigated in the presence of three types of quantized optical fields, i.e., coherent, amplitude-squeezed, and phase-squeezed fields, in comparison with the case of classical laser fields. The constituent monomers are assumed to interact with each other by the dipole-dipole interaction, and the two-exciton model, which takes into account both the one- and two-exciton generations, is employed. As shown in previous studies, near-degenerate exciton states in the presence of a (near) resonant classical laser field create quantum superposition states and thus cause the spatial exciton recurrence motion after cutting the applied field. In contrast, continuously applied quantized optical fields turn out to induce similar exciton recurrence motions in the quiescent region between the collapse and revival behaviors of Rabi oscillation. The spatial features of exciton recurrence motions are shown to depend on the architecture of aggregates. It is also found that the coherent and amplitude-squeezed fields tend to induce longer-term exciton recurrence behavior than the phase-squeezed field. These features have a possibility for opening up a novel creation and control scheme of exciton recurrence motions in aggregate systems under the quantized optical fields.     

Cathode materials for lithium-sulfur battery: a review

Journal of Solid State Electrochemistry - Lithium-sulfur batteries (LSBs) are considered to be one of the most promising candidates for becoming the post-lithium-ion battery technology, which would...     

A new crosslinkable polyphenol from a renewable resource

Cardanol, a major component obtained by thermal treatment of cashew nut shell liquid, is a phenol derivative mainly having a C15 unsaturated hydrocarbon chain with 1–3 double bonds at the m‐position. We polymerized cardanol using an Fe‐salen complex as the catalyst to give a soluble polyphenol containing the unsaturated alkyl group in the side chain. The polymer was subjected to hardening by a cobalt naphthenate catalyst or thermal treatment, yielding crosslinked film with high gloss surface.     

Synthesis and radical polymerization of end-methacrylated poly(succinimide) leading to poly(aspartic acid) hydrogel

The polycondensation of aspartic acid in the presence of phthalic anhydride was carried out in mesitylene/sulfolane using o-phosphoric acid as a catalyst. The polymer yields were 91–78%, when 5–20 mol-% phthalic anhydride was added into the feed. The obtained poly(succinimide) carried a phthalic imide unit and a succinic acid unit as end groups. In the MALDI-TOF mass spectrum, the peak-to-peak distances between adjacent signals were 97.07 m/z, corresponding to the calculated value (97.07) of the succinimide unit. Poly(succinimide) was reacted with 2-(methacryloxy)ethyl isocyanate to give end-methacrylated poly-(succinimide), in which the end-functionality of the methacrylate group was ca. 1. End-methacrylated poly-(succinimide) was polymerized with ethylene glycol dimethacrylate using 2,2′-azoisobutyronitrile to give poly(succinimide) gel, which could be converted into water-absorbing poly(aspartic acid) hydrogel.     

Synthesis of Hyperbranched Polysaccharide by Thermally Induced Cationic Polymerization of 1,6-Anhydrohexopyranose

The thermally induced cationic polymerizations of 1,6-anhydro-β-D -glucopyranose ( 1a ), 1,6-anhydro-β-D -mannopyranose ( 1b ) and 1,6-anhydro-β-D -galactopyranose ( 1c ) as a latent cyclic AB₄-type monomer were carried out using (S-2-butenyl)tetramethylenesulfonium hexafluoroantimonate ( 2 ) as an initiator. The solution polymerization in propylene carbonate proceeded without gelation to produce the water-soluble hyperbranched polysaccharides ( 3a-c ) with controlled molecular weights and narrow polydispersities. The degree of branching (DB), estimated by the methylation analysis of 3a-c , was in the range of 0.38 – 0.49. The thermally induced cationic polymerization of 1a-c using 2 is a facile method leading to a hyperbranched polysaccharide with a high DB value.