General Method to Correct the Fluctuation of Acid Based Pretreatment Efficiency of Lignocellulose for Highly Efficient Bioconversion

Acid based pretreatment efficiency frequently changes with the varying properties of raw lignocellulose feedstock and creates disturbances in industrial biorefining applications. This study revealed that high alkaline ash content in feedstocks neutralized partial acid catalyst and consequently reduced the pretreatment efficiency. The ash content varies in each batch of feedstocks by differences in growing regions, seasons, irrigation, soil, fertilizer use, harvest operation, transportation, storage, and prehandling operations. These differences lead to frequent and significant fluctuations of acid based pretreatment efficiency. The practical solution to the fluctuation should be simple and fast, preferably without performing a time-consuming pretreatment operation assay. Here we proposed a Base pH Approaching method to correct the fluctuating pretreatment efficiency by a simple titration procedure. The method contained only two simple steps in flasks. The first step is the measurement of the inherent base pH value of the thoroughly washed feedstock slurry, and the second step is the adjustment of sulfuric acid usage by titration of the feedstock slurry to the base pH value. The method is universally effective to different feedstocks (corn stover, wheat straw, or rice straw) using different strains (yeasts or bacteria) for different products (ethanol and lactic acid) and different fermentation types (SSF or SSCF)

VSMC MIMO: A spectral efficient scheme for cooperative relay in cognitive radio networks

Multiple-Input Multiple-Output (MIMO) technology has become an efficient way to improve the capacity and reliability of wireless networks. Traditional MIMO schemes are designed mainly for the scenario of contiguous spectrum ranges. However, in cognitive radio networks, the available spectrum is discontiguous, making traditional MIMO schemes inefficient for spectrum usage. This motivates the design of new MIMO schemes that apply to networks with discontiguous spectrum ranges. In this paper, we propose a scheme called VSMC MIMO, which enables MIMO nodes to transmit variable numbers of streams in multiple discontinuous spectrum ranges. This scheme can largely improve the spectrum utilization and meanwhile maintain the same spatial multiplexing and diversity gains as traditional MIMO schemes. To implement this spectral-efficient scheme on cooperative MIMO relays in cognitive radio networks, we propose a joint relay selection and spectrum allocation algorithm and a corresponding MAC protocol for the system. We also build a testbed by the Universal Software Radio Peripherals (USRPs) to evaluate the performances of the proposed scheme in practical networks. The experimental results show that VSMC MIMO can efficiently utilize the discontiguous spectrum and greatly improve the throughput of cognitive radio networks.EICPCI-S(ISTP)[email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]