High oil prices, increasing focus on renewable carbohydrate-based feedstocks for fuels and chemicals, and the recent publication of its genome sequence, have provided continuing stimulus for studies on Zymomonas mobilis. However, despite its apparent advantages of higher yields and faster specific rates when compared to yeasts, no commercial scale fermentations currently exist which use Z. mobilis for the manufacture of fuel ethanol. This may change with the recent announcement of a Dupont/Broin partnership to develop a process for conversion of lignocellulosic residues, such as corn stover, to fuel ethanol using recombinant strains of Z. mobilis. The research leading to the construction of these strains, and their fermentation characteristics, are described in the present review. The review also addresses opportunities offered by Z. mobilis for higher value products through its metabolic engineering and use of specific high activity enzymes.

We investigate defect modes of cholesteric liquid crystals as photonic band gap materials. For normal incidence of light, cholesteric liquid crystals exhibit total reflection for the circular polarization with the same handedness as that of cholesteric helix. However, the other orthogonal component is completely transmitted. When we replace a thin layer of liquid crystal by an isotropic material as a defect, defect modes are induced for both polarizations of incident light. We analyze the wavelength and reflectivity of the defect modes in terms of the refractive index of defect layer.

This paper firstly reports key factors which are to be necessarily considered for the successful two-bit (four-level) cell operation in a phase-change random access memory (PRAM). They are 1) the writeand-verify (WAV) writing of four-level resistance states and 2) the moderate-quenched (MQ) writing of intermediate resistance levels, 3) the optimization of temporal resistance increase (so-called resistance drift) and 4) of resistance increase after thermal annealing. With taking into account of them, we realized a two-bit cell operation in diodeswitch phase change memory cells with 90nm technology. All of four resistance levels are highly write endurable and immune to write disturbance above 10 8 cycles, respectively. In addition, they are nondestructively readable above 10 7 read pulses at 100ns and 1uA. IntroductionPhase-change random access memory (PRAM) is most promising to realize a multi-level cell (MLC) operation because it has very wide range of resistance across two orders of magnitude or the higher, with respect to writing current. According to the PRAM road map [1], it is expected that highest memory densities of PRAM become comparable to conventional memories such as NOR Flash and DRAM in coming years when MLC operation is fully accomplished. In this paper, we systematically investigated a four-level (two-bit) cell operation in diode-switch phase change memory cells with 90nm technology and discussed its possibilities and issues as well.

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Aims:  To evaluate sugar recoveries and fermentabilities of eight lignocellulosic raw materials following mild acid pretreatment and enzyme hydrolysis using a recombinant strain of Zymomonas mobilis. Methods and Results:  Dilute acid pretreatment (2% H2SO4) with 10% (w/v) substrate loading was performed at 134°C for 60 min followed by enzyme hydrolysis at 60°C. The results demonstrated that hydrolysis of herbaceous raw materials resulted in higher sugar recoveries (up to 60–75%) than the woody sources (<50%). Fermentation studies with recombinant Z. mobilis ZM4 (pZB5) demonstrated that final ethanol concentrations and yields were also higher for the herbaceous hydrolysates. Significant reduction in growth rates and specific rates of sugar uptake and ethanol production occurred for all hydrolysates, with the greatest reductions evident for woody hydrolysates. Further studies on optimization of enzyme hydrolysis established that higher sugar recoveries were achieved at 50°C compared to 60°C following acid pretreatment. Conclusions:  Of the various raw materials evaluated, the highest ethanol yields and productivities were achieved with wheat straw and sugarcane bagasse hydrolysates. Sorghum straw, sugarcane tops and Arundo donax hydrolysates were similar in their characteristics, while fermentation of woody hydrolysates (oil mallee, pine and eucalyptus) resulted in relatively low ethanol concentrations and productivities. The concentrations of a range of inhibitory compounds likely to have influence the fermentation kinetics were determined in the various hydrolysates. Significance and Impact of the Study:  The study focuses on lignocellulosic materials available for second generation ethanol fermentations designed to use renewable agricultural/forestry biomass rather than food‐based resources. From the results, it is evident that relatively good sugar and ethanol yields can be achieved from some herbaceous raw materials (e.g. sugarcane bagasse and sorghum straw), while much lower yields were obtained from woody biomass.

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