Fermentative production of cadaverine from renewable resources may support a sustainable biorefinery process to produce carbon-neutral nylons such as biopolyamide 510 (PA510). Cost-competitive production of cadaverine is a key factor in the successful commercialization of PA510. In this study, an integrated biological and chemical process involving cadaverine biosynthesis, purification, and its polymerization with sebacic acid was developed to produce bio-PA510. To stably express ldcC from Escherichia coli in an engineered Corynebacterium glutamicum PKC strain, an expired industrial L-lysine-producing strain, ldcC, was integrated into the chromosome of the C. glutamicum PKC strain by disrupting lysE and controlling its expression via a strong synthetic H30 promoter. Cadaverine was produced at a concentration of 103.78 g/L, the highest titer to date, from glucose by fed-batch culture of this engineered C. glutamgicum PKC strain. Fermentation-derived cadaverine was purified to polymer-grade biocadaverine with high purity (99%) by solvent extraction with chloroform and two-step distillation. Finally, biobased PA510 with good thermal properties (T m 215 °C and T c 158 °C) was produced by polymerization of purified cadaverine with sebacic acid. The hybrid biorefinery process combining biological and chemical processes demonstrated in this study is a useful platform for producing biobased chemicals and polymers.

The surface phonon mode of CdSe quantum dots in a glass matrix was investigated by Raman spectroscopy. The blueshift and broadening of the surface phonon frequency were observed as the quantum dot size was reduced. It was shown that the observed size-dependent blueshift and broadening are mainly caused by the lattice contraction and the boundary relaxation, respectively. ͓S0163-1829͑99͒00811-5͔

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We report the light emission decay in bare gold nanoparticles by using the fluorescence up-conversion technique. The emission decay, of which the time constants increase consistently with excitation intensity, closely follows the electron thermalization dynamics, which has been independently observed from the bleach recovery of the surface plasmon band under the identical experimental conditions. These results indicate that a weak light emission from relatively large gold nanoparticles is attributable to the interactions between surface plasmons and incident photons, which occur simultaneously with the thermal electron relaxation.

The Ge2Sb,Tes (GST) thin film is well known to play a critical role in PRAM (Phase Change Random Access Memory). Through device simulation, we found that highresistive GST is indispensable to minimize the writing current of PRAM. For the first time, we tried to increase the GST resistivity by doping nitrogen. Doping nitrogen to GST successfully reduced writing current. Also, the cell endurance

Transient absorption anisotropies of the Zn(II)porphyrin monomer, its direct meso–meso coupled dimer, and trimer are measured in the B (Soret) band region by sub-30 fs laser pulses. It is shown that detailed information on the electronic structures and energy transfer dynamics can be obtained from the anisotropy and the magic angle data. The anisotropies of all three molecules exhibit remarkable behaviors in the first 200 fs region. Experimental observations can be accounted for adequately by treating the transient absorption signal as an explicit sum of ground state bleach and excited state stimulated emission contributions. In the monomer, the anisotropy decay denotes an oscillatory feature followed by a 100 fs time constant exponential decay. It is argued that the Bx and By transitions of the porphyrin monomer are nondegenerate with an energy splitting of ∼170 cm−1. Furthermore, equilibration of the excitation energy within the B states is slightly underdamped. Excitation of the monomerlike B band of the dimer (trimer) leads to ultrafast ∼30 fs (60 fs) anisotropy decay and a subsequent rise with ∼60 fs (70 fs) time constant. It is concluded that the anisotropy decay is due to the ultrafast energy transfer to the low-energy exciton split B band, while the rise is due to the redshift of the excited state stimulated emission spectrum thereby decreasing the contribution of the excited state stimulated emission component in the overall transient absorption signal.

We report the femtosecond transient absorption dynamics of the gold and gold-polypyrrole nanoparticles by photoexcitation at various wavelengths. The bleach recovery dynamics of the surface plasmon band for the gold and gold-polypyrrole nanoparticles exhibit different responses to the pump beam energy and intensity in thermal energy transfer from the gold nanoparticles to the surrounding medium or embedding material. This indicates that directly attached polypyrroles provide fast thermal energy transfer pathways for the core gold nanoparticles.

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