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To convert carbohydrates into platform compounds, the deep eutectic solvent (DES) based on choline chloride and urea (molar ratio 1:2) was adopted as a green solvent. The physical properties of den...

Loss of energy potential during storage is a significant consideration when using crop residues for bioenergy production. However, previous studies about biomass storage only reported dry matter loss and composition change, but not the direct effects on bioenergy production. This study investigated the changes in chemical composition, enzymatic digestibility, and methane yield of corn stover after one-year outdoor dry bale storage under covered and uncovered conditions. The contents of easily degradable components, including extractives and hemicellulose, decreased by about 20%–50%, while the contents of cellulose and lignin did not change significantly. The methane yields of corn stover after one-year covered or uncovered storage declined by 13.2% and 22.7%, respectively, partially due to the decrease of cellulose degradability and the losses of hemicellulose and extractives. Increasing particle size from 1 mm to 12.7 mm reduced the methane yield of the stored corn stover by up to 26.4%. The modified Gompertz model suggested that both storage conditions and particle size affected methane yield, maximum methane production rate, and lag phase time of anaerobic digestion (AD) of corn stover. The information reported in this paper can provide important information for economic analysis and life cycle analysis of AD of corn stover.

The liquid-liquid equilibrium (LLE) data for the ternary systems of ethyl acetate + 2,2,3,3-tetrafluoro-1-propanol + water and isopropyl acetate + 2,2,3,3-tetrafluoro-1-propanol + water were measured at T = 298.15 K and T = 318.15 K under 101.3 kPa. Bachman and Hand equations were selected to check and confirm the reliability of the measured tie-line data, and the correlation coefficient (R2) were all close to 1. Meanwhile, the distribution coefficient and separation factor were calculated and discussed in detail. In addition, the nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models were applied to correlate the experimental data, and the RMSD values for the two models obtained are 0.0104, 0.0104 correlated by NRTL, and 0.0077, 0.0128 by UNIQUAC, respectively, which indicate that the experimental LLE data can be successfully correlated by both the NRTL and the UNIQUAC models. Also, the corresponding binary interaction parameters were regressed. The correlated model parameters could be applied for the optimization and design of the separation process.

To reduce the environmental pollution caused by organic solvents and improve the extraction efficiency, a range of natural deep eutectic solvents (NADESs) was explored for the extraction of green tea polyphenols (TPs). The use of the NADESs, especially ChCl/EG (Choline chloride/Ethylene glycol, molar ratio 1:2), can increase extraction efficiency when comparing with the traditional solvents. Then response surface methodology (RSM) was used for the optimization of TPs extraction with ChCl/EG. The perfect regression prediction model was generated and the highest TPs extraction yield of 20.12% was achieved, highlighting the potential of NADES for TPs extraction. Meanwhile, the applicability of COSMO-SAC (Conductor-like screening model for segment activity coefficient) for evaluation of TPs extractability in different solvents was investigated. Epigallocatechin gallate (EGCG) was employed as the TPs model solute. Geometry optimization and energy optimization of EGCG and these solvents were performed via COSMO-SAC. The extraction performance of the solvents was interpreted by the analysis of activity coefficient at infinite dilution (γ∞). The result showed that the higher the extraction yield, the lower the lnγ∞. The σ-profile and the interaction energy (EINT) were generated to analyse the molecular interaction between solvent and solute. It was demonstrated that the combination of a strong hydrogen bond acceptor (HBA) - ChCl, with a relatively weaker hydrogen bond donor (HBD) - EG, resulted in a NADES (ChCl/EG) with a stronger affinity to TPs. This work provided both experimental and intermolecular insight to help choose effective solvent for bioactive components extraction in further research.

Ternary liquid–liquid equilibrium (LLE) data of 2,2,3,3,4,4,5,5-octafluoro-1-pentanol + methanol + water were measured at (298.15, 308.15, and 318.15) K under atmospheric pressure. Both the Bachman and the Hand equations were applied to check the reliability of the tie-line data, and their correlation coefficient (R2) were all close to 1. Meanwhile, the nonrandom two-liquid (NRTL) activity coefficient model was applied to correlate the experimental data, which the results showed good agreement with the measured LLE data, and the binary interaction parameters were regressed. In addition, the distribution coefficients and separation factors were determined by using the experimental data and discussed in detail.

Evaluating the technical feasibility and economic viability of citric acid production at the commercial scale is challenging because it depends on several factors including type of feedstock, process parameters and production routes. In this research, techno-economic and environmental impacts of citric acid production from corn are comparatively evaluated for three scenarios. In the production process Aspergillus niger is used for corn fermentation in a commercial scale of 6400 kg/h citric acid production rate. The scenarios are defined based on application of three recovery methods, including calcium precipitation, solvent extraction, and ion exchange. From three investigated scenarios, the lowest selling price of citric acid is achieved in a scenario using solvent extraction recovery method, followed by the scenario with calcium precipitation recovery method. Sensitivity analysis shows that the minimum selling price of citric acid is highly sensitive to electricity cost, by-product credit, corn supply cost, fermentor cost and wastewater treatment cost. Environmental impacts of citric acid production in three scenarios are assessed using the life cycle assessment approach. Citric acid production with ion exchange recovery method is the most environment-friendly scenario. The results of this research are useful for the development of citric acid production in commercial scale.

Organic–inorganic hybrid lead halide perovskites have been widely investigated in optoelectronics both experimentally and theoretically. The present work incorporates chemically modified graphene into nanocrystal SnO2 as the electron transporting layer (ETL) for highly efficient planar perovskite solar cells. The modification of SnO2 with highly conductive two-dimensional naphthalene diimide-graphene can increase surface hydrophobicity and form van der Waals interaction between the surfactant and the organic–inorganic hybrid lead halide perovskite compounds. As a result, highly efficient perovskite solar cells with power conversion efficiency of 20.2% can be achieved with an improved fill factor of 82%, which could be mainly attributed to the augmented charge extraction and transport.

Liquid–liquid equilibrium (LLE) data for the ternary system 2,2,3,3,4,4,5,5-octafluoro-1-pentanol + ethanol + water have been reported at (298.15, 308.15, and 318.15) K and 0.1 MPa. The Bachman equation and the Hand equation were used to confirm the reliability of the experimental tie-line data. The experimental data were correlated by the nonrandom two-liquid (NRTL) model, for which the calculated results show good agreement with the ternary LLE data, and the binary interaction parameters of NRTL model were also regressed. Moreover, the distribution coefficients and separation factors in the ternary system were determined by the experimental data.

Anaerobic digestion (AD) of minimal nutrient-supplemented wheat straw and digestate liquor recycle was evaluated in semi-continuous processes using a novel BioReactor Simulator developed for easy accurate online normalised-gas measurement. Three scenarios (i) no recycle (NR), (ii) recycle of soluble nutrient (RSN), and (iii) recycle of nutrient and microbes (RNM) were investigated in order to evaluate their respective efficiencies. Although mono-digestion of lignocellulosic biomasses are often performed with very long solid retention times (SRT), the present study demonstrated an efficient process operating with a 30-day SRT and an organic loading rate of 4 gVS/L d. The best methane yield was 303 mLCH(4)/g VS achieved in the RSN process showing a 21% improvement as compared to the NR process. The methanogenic potential of the digestates from the RSN and RNM processes was comparable to fresh inoculum indicating efficient processes. The RNM and RSN processes showed superior process stability evidenced by minimal volatile fatty acid accumulation (

Rice, as a major crop in the world, produces huge agronomic biomass residues besides food, which consist of cellulose, hemicelluloses and lignin. Many master regulators of secondary wall synthesis were identified in the model plant Arabidopsis. In this study, we investigated the function of a NAC (NAM, ATAF, and CUC2) transcription factor related to secondary cell wall biosynthesis, which is highly expressed in rice sclerenchyma tissue and is named OsSWN1. Our results showed that engineering of OsSWN1 could exhibit multiple features regulated to agronomic traits and bioenergy research. Over-expression of OsSWN1 caused an erect-leaf and enclosed-flower phenotype. Secondary cell wall-related genes were actively expressed in transgenic plants with obvious ectopic lignin deposition in the leaf collar, while increased lignin content and decreased the sugar yield correspondingly. In addition, down-regulation of OsSWN1 expression levels decreased lignin content and increased the sugar yield in transgenic plants. Bioinformatics analysis revealed that OsSWN1-like genes are highly conserved in switchgrass and sorghum, suggesting a possibility of manipulating the expression level of the OsSWN1 orthologs in the bioenergy crops for biofuel production.

Corn stover fractions (leaves, cobs, and stalks) were studied for enzymatic digestibility after pretreatment with a white rot fungus, Ceriporiopsis subvermispora. Among the three fractions, leaves had the least recalcitrance to fungal pretreatment and the lignin degradation reached 45% after 30 days of pretreatment. The lignin degradation of stalks and cobs was similar but was significantly lower than that of leaves (p < 0.05). For all fractions, xylan and glucan degradation followed a pattern similar to lignin degradation, with leaves having a significantly higher percentage of degradation (p < 0.05). Hydrolytic enzyme activity also revealed that the fungus was more active in the degradation of carbohydrates in leaves. As a result of fungal pretreatment, the highest sugar yield, however, was obtained with corn cobs.

This article focuses on improving the system capacity of 60-GHz wireless personal area networks WPANs and presents an effective time slot allocation scheme for spatial reuse, which combines the existing exclusive region ER-based scheduling algorithm with simple power control. In the study, the concept of ER for concurrent transmissions is introduced first. Considering the large path loss in the millimeter-wave band and the characteristics of typical indoor multipath channels, we generalize the signal propagation model as well as ER radius for 60-GHz WPANs. Then, we propose an improved ER-based scheduling algorithm, which employs power control instead of constant transmitting power. In this algorithm, devices are assumed to receive data at the receiver sensitivity, which refers to the minimum receiving power to ensure the reliability for communications. Implementation feasibility is provided within the current standards framework. Some more practical analysis based on the beamforming codebook specified by of the IEEE 802.15.3c standard is also developed. In addition, the impact of the antenna radiation efficiency and receiver sensitivity is discussed. Computer simulations validate the excellent performance of the proposed scheme, which can significantly improve the channel capacity under different antenna configurations. Copyright © 2012 John Wiley & Sons, Ltd.

The spent wheat straw from horse stall bedding has lower cellulose and hemicellulose contents, but higher volatile fatty acid content than raw wheat straw. Biogas production from solid-state anaerobic digestion (SS-AD) of spent wheat straw and raw wheat straw was compared in this study. The SS-AD tests were conducted at 22% total solids (TS) content using inoculum from a liquid AD system at three feedstock-to-inoculum (F/I) ratios of 2.0, 4.0, and 6.0. Daily methane yields of spent wheat straw peaked 8 and 3 days earlier than those of raw wheat straw at F/I ratios of 2.0 and 4.0, respectively. The highest methane yield of 150.0 L/kg volatile solids (VS) was obtained from spent wheat straw at an F/I ratio of 4.0, which was 56.2% higher than that of raw wheat straw. The corresponding cellulose and hemicellulose degradation of spent wheat straw was 24.1% and 49.4% higher than those of raw wheat straw, respectively.

Storage of lignocellulosic biomass is critical for a year-round supply of feedstock for a biorefinery. Compared with dry storage, wet storage is a promising alternative technology, providing several advantages including reduced dry matter loss and fire risk and improved feedstock digestibility after storage. This study investigated the concurrent pretreatment and wet-storage of corn stover with the assistance of NaOH or a lignin-degrading fungus, Ceriporiopsis subvermispora , during a 90-d period. Compared with ensilage, adding NaOH or inoculation with C. subvermispora significantly enhanced the enzymatic degradability of corn stover by 2–3-fold after 90-d wet storage. Lignin and xylan removal during NaOH pretreatment and wet-storage were influenced by NaOH loading and moisture. NaOH pretreatment retarded the production of organic acids during storage and the acetate release correlated with lignin and xylan removal. Further study is needed to reduce cellulose degradation during the late stage of fungal treatment.

In this paper, we propose an efficient timeslot allocation scheme to manage the network resource for a centralized indoor network under 60GHz millimeter-wave unlicensed spectrum. We develop a system model where both AP (access point) and devices are equipped with array antennas to improve the poor link budget in the 60GHz band. And the beamforming weighting vectors defined in the standard of IEEE 802.15.3c are employed in the system. Jain's fairness index in terms of the number of slots assigned to each device is adopted to ensure the fairness of the algorithm. Then, extensive simulations are conducted to demonstrate the accuracy of the analytical model and the efficiency of the proposed algorithm. The analysis and simulation results show that the proposed algorithm can always outperform the existing one at channel capacity, schedule length and fairness.

This article puts forward a method for codebook design to support beamforming mechanism in a 60GHz millimeter-wave wireless communication environment. The codebook is designed with only phase shifting but not any amplitude adjustment to meet the low power consumption requirement. IEEE802.15.3c beam MRA (main response axis) directions are taken as the original version to make curve fitting, so that weighting vector based on uniform weighting can be obtained to generate a codebook matrix. The simulation results show that, compared with the codebook in IEEE802.15.3c, similar main lobe patterns can be obtained in the proposed codebook, while the side lobe level is lower and the antenna gain at the direction of MRA is higher. Meanwhile, the interference decreases obviously with an improved network channel capacity in the practice environment, and the codebook is also robust to the beam shifting deriving from phase errors.

Wheat straw is one of the most commonly used bedding materials in horse stall. The finished straw bedding materials, or horse mulch, has lower cellulose and hemicellulose contents, whereas higher total volatile fatty acids (total VFA) concentration than wheat straw. Biogas production from solid-state anaerobic digestion (SS-AD) of horse mulch and wheat straw was compared in this study. The SS-AD tests were conducted at 22% total solids (TS) content using effluent from a liquid AD as inoculum at three feedstock-to-inoculum (F/I) ratios of 2.0, 4.0 and 6.0. Daily methane yield of horse mulch peaked earlier than that of wheat straw. The highest methane yield of 150.0 L/kg volatile solids (VS) was obtained from horse mulch at F/I ratio of 4.0, which was 56.2% higher than that of wheat straw. The corresponding cellulose and hemicellulose degradations of horse mulch were 24.1% and 49.4% higher than those of wheat straw, respectively.