Measurement of the decay and time-resolved spectra of the emission from σ-excitons in KBr in the nanosecond range,produced by heavy-ion irradiation

While energetic heavy ions are currently in increasing use in solid state physics, radiation chemistry and biology, there is still little experimental information regarding the primary physicochemical processes. These high LET (linear energy transfer) ion particles injected into condensed matter produce short life-intermediates such as excited states, ions, and radicals, at high density along the track. The density effect of these intermediates may cause damage-formation and chemical reaction to yield different results compared with low LET radiation (γ, X-ray) or photo-irradiation. Electronically excited states, among the above intermediates, are thought to be especially important precursors. Measurements of the decay and time-resolved spectra of the emission are expected to give useful information regarding the radiation action of heavy ions. The measurements were done using a KBr single crystal at 4.2 K. We reported previously [1] that heavy ion irradiated KBr results in an extraordinarily large ratio of σ-emission to π-emission 2 intensity (～ 5 times larger than in the X- or electron-irradiation). This large ratio is, as was ascertained previously, not due to apparent processes such as temperature increase of a track but to intrinsic processes which will be discussed here.     

Sulfur-containing polymers. V. Preparation of polyoxycarbonylsulfenamides by polycondensation of bis(oxycarbonylsulfenyl chlorides) with diamines

Polyoxycarbonylsulfenamides (POSA) have been prepared by interfacial polycondensation of bis(oxycarbonylsulfenyl chlorides) with diamines. The polymers obtained ranged in physical form from crystalline solids to resinous materials depending on the kind of both bis(oxycarbonylsulfenyl chlorides) and diamines used. Some of the polymers gave transparent pliable films from chloroform solution. The polymer films decomposed with liberation of carbonyl sulfide on being subjected to ultraviolet radiation.     

A convenient method for the synthesis of (E)-3-alkenoic acids by a regio- and stereoselective reaction of β-vinyl-β-propiolactone with organocopper reagents

β-Vinyl-β-propiolactone reacts regio- and stereoselectively with Grignard reagents in the presence of copper(I) catalyst or with diorganocuprates to afford (E)-3-alkenoic acids in high yields.     

A novel five-carbon homologation leading to 3,4-alkadienoic acids by SN2′ reaction of β-ethynyl-β-propiolactone with grignard reagents in the presence of copper(i) catalyst

β-Ethynyl,-β-propiolactone reacts regioselectively with Grignard reagents in the presence of copper(I) catalyst to afford 3,4-alkadienoic acids in high yields. Synthetic utility of this reaction is demonstrated in the simple synthesis of pellitorine.     

Preparation of composite monoliths of quaternized chitosan and diatom earth for protein separation

In this study, composite monoliths with porous structures were prepared using quaternized chitosan and diatom earth for protein separation. Quaternized chitosan (N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride) dissolved in water was mixed with diatom earth and crosslinked with glutaraldehyde under low-temperature conditions to form a cryogel. Interconnected porous monoliths were obtained after removing ice crystals from the cryogel. The monoliths adsorbed bovine serum albumin selectively from the solution mixture of bovine serum albumin and bovine ɤ-globulin, and bovine ɤ-globulin was recovered in the flow-through fraction. The adsorption selectivity was enhanced by changing the solution pH from 6.8 to 5.5. The adsorption of bovine serum albumin by the monolith was replicated at least five times following its washing with a buffer containing 400 mM NaCl and subsequent regeneration with a 10 mM acetate buffer. The composited monolith is a promising adsorbent for the removal of acidic proteins, such as serum albumin contamination in neutral proteins, for example, ɤ-globulins, in bioproduction processes.     

Radical-scavenging activity of natural methoxyphenols vs. synthetic ones using the induction period method

The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X = NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC) by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activity and the induction period for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO). 2-Allyl-4-methoxyphenol and 2,4-dimethoxy-phenol scavenged not only oxygen-centered radicals (PhCOO*) derived from BPO, but also carbon-centered radicals (R*) derived from the AIBN and DPPH radical much more efficiently, in comparison with eugenol and isoeugenol. 2-Allyl-4-methoxyphenol may be useful for its lower prooxidative activity.     

Vibrational overtone induced elimination reactions within hydrogen-bonded molecular clusters: the dynamics of water catalyzed reactions in CH2FOH.H2On

The dynamics of the light initiated OH-overtone induced elimination reactions CH(2)FOH.(H(2)O)(n) + hnu--> HF + CH(2)O + n(H(2)O), n = 1-3, are studied using classical trajectory simulations where the ab initio potential energy surface is computed "on-the-fly". Hydrogen bonding to the water is found to lower the barrier to reaction by over 20 kcal mol(-1) and modifies the mechanism to a concerted multiple H-atom transfer process. The reaction process is found to occur on a rapid timescale, <100 fs, and involves the hydronium ion as an intermediate. An essential aspect of dynamics is the successful competition of reaction with energy dissipation through water evaporation from the cluster.     

Spectroscopic and electronic structure studies of the diamagnetic side-on CuII-superoxo complex Cu(O2)[HB(3-R-5-iPrpz)3]: antiferromagnetic coupling versus covalent delocalization

Magnetic, vibrational, and optical techniques are combined with density functional calculations to elucidate the electronic structure of the diamagnetic mononuclear side-on CuII-superoxo complex. The electronic nature of its lowest singlet/triplet states and the ground-state diamagnetism are explored. The triplet state is found to involve the interaction between the Cu xy and the superoxide pi v * orbitals, which are orthogonal to each other. The singlet ground state involves the interaction between the Cu xy and the in-plane superoxide pi v * orbitals, which have a large overlap and thus strong bonding. The ground-state singlet/triplet states are therefore fundamentally different in orbital origin and not appropriately described by an exchange model. The ground-state singlet is highly delocalized with no spin polarization.     

Beta-1,3-glucan (schizophyllan) can act as a one-dimensional host for creation of novel poly(aniline) nanofiber structures

We here demonstrate the creation of novel poly(aniline) (PANI) nanofiber structures by a polymer wrapping method using schizophyllan (SPG). Mannose-modified SPG can also wrap PANIs to give nanofibers having a lectin affinity. This interaction is applicable to designing novel PANI/protein composites. The results establish that SPG can act as a novel "host" to assemble PANIs into one-dimensional superstructures. [reaction: see text]