Research Articles

Although some engineered S. cerevisiae strains exhibit good xylose utilization ability, the lack of tolerance to inhibitors generated in biomass pretreatment limits the application of such strains in the production of bioethanol from lignocellulosic biomass. By applying a sexual mating method, inhibitor tolerance was developed in xylose-utilizing strains. The final ethanol concentrations in simultaneous scarification and co-fermentation (SScF) process at 38 °C with hybrid strains were 50% higher than the SScF process with the xylose-fermenting parent strain. The strain viability of the hybrid strain E7-12 at 24 h was 282 times higher than the parent strain in the SScF process at 25% solid loading. Due to the improved sugar utilization, the final ethanol concentration reached 69.7 g/L (E7-11) and 70.0 g/L (E7-12), which were 25.3 g/L and 25.6 g/L higher than that of SScF with the xylose-fermenting strain, respectively.

The impact of the trucking transportation network flow was modeled for the southern United States. The study addresses a gap in existing research by applying a Bayesian logistic regression and Geographic Information System (GIS) geospatial analysis to predict biorefinery site locations. A one-way trucking cost assuming a 128.8 km (80-mile) haul distance was estimated by the Biomass Site Assessment model. The “median family income,” “timberland annual growth-to-removal ratio,” and “transportation delays” were significant in determining mill location. Transportation delays that directly impacted the costs of trucking are presented. A logistic model with Bayesian inference was used to identify preferred site locations, and locations not preferential for a mill location. The model predicted that higher probability locations for smaller biomass mills (feedstock capacity, the size of sawmills) were in southern Alabama, southern Georgia, southeast Mississippi, southern Virginia, western Louisiana, western Arkansas, and eastern Texas. The higher probability locations for large capacity mills (feedstock capacity, the size for pulp and paper mills) were in southeastern Alabama, southern Georgia, central North Carolina, and the Mississippi Delta regions.

A series of novel rice husk char/poly-(acrylic acid(AA)-co-acrylamide(AM)) superabsorbent hydrogels were synthesized by graft copolymerization. The effects of the rice husk char (RHC) loading on their miscibility, shapes, and chemical structures were studied, and their swelling behaviors, kinetics, and pH response were evaluated. During the preparation, RHC reacted with acrylic acid. The RHC at lower loads (< mass ratios of RHC and AA of 1%) was scattered well within the polymer matrix, but an excessive load might result in the formation of large agglomerates. The swelling capacity and swelling rate of the hydrogels first were both increased with the rising RHC loading to 1% and then declined with further RHC loading. The superabsorbent hydrogel containing 1% RHC had the highest water absorbency (869 g/g in deionized water and 97 g/g in 0.9% NaCl solution).

To utilize the lignin generated by the paper industry and reduce the cost of poly(lactic acid) (PLA), PLA/lignin composites were prepared from PLA and different ratios of lignosulfonate (LS) or desulfonated lignosulfonate (DLS) particles using a casting method. The physicochemical properties of the lignins were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation-high performance liquid chromatography (GPC), and elementary analysis. The results indicate that the sulfur content of the original LS was successfully reduced to half by desulfonation to produce DLS, which was found to have a higher thermal stability and a lower average molecular weight than LS. Additionally, the thermal stability, crystallization, compatibility, mechanical, hydrophobicity, and optical properties of the PLA/lignin composites were also meticulously evaluated. Comparison of the PLA/DLS and PLA/LS composites revealed that the incorporation of DLS into PLA improved compatibility, thermal stability (T5% and Tmax), and hydrophobicity, while the mechanical properties remained almost unchanged. In addition, both PLA/DLS and PLA/LS exhibited UV light absorption capacity. Finally, the low-rate addition of both LS (10%) and DLS (5%) accelerated the crystallization of PLA, but crystallization was delayed with higher lignin content.

The steam reforming of acetic acid (SRA) was carried out in a fixed-bed tubular reactor with Ni-Fe/ceria-palygorskite (CPG) catalysts. The as-prepared catalysts were analyzed by N2 adsorption-desorption, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), H2 temperature programmed reduction (H2-TPR), and X-ray diffraction (XRD). The results of H2-TPR and XRD showed that the addition of CeO2 increased the hydrogen consumption of catalysts and the interaction force between active component (Ni-Fe alloy) and carrier. Moreover, the Ni-Fe alloys were successfully synthesized in the Ni-Fe/CPG catalysts and their crystallite sizes were decreased by adding CeO2. In addition, these catalysts were employed to SRA at 600 °C, GHSV = 14427 h-1 and different molar ratio of S/C. The experimental results revealed that the Ni-Fe/C0.4PG0.6 catalyst can achieve the highest yield of H2 (87%) and HOAc conversion (95%), as well as the highest stability during the process of steam SRA. Additionally, the spent catalysts were characterized by XRD, SEM, and thermogravimetric analysis (TGA). The results showed that the addition of CeO2 enhanced the stability and activity of Ni-Fe/palygorskite catalyst and reduced the coke deposition rate on the catalyst surface.

Paper is widely used as a substrate for inkjet printing, where the paper feature heavily impacts the print quality, especially the color reproduction. The unprinted area on paper is visible and applied as a background reflectance for the toner layer. Hence, it is worthwhile to understand the effects of paper whiteness on print color reproduction. In this study, the tested papers were treated with different dyes, which resulted in the change of the paper’s optical properties, but not surface roughness. The print density was impacted by the paper whiteness and ISO brightness. The effect of the paper whiteness on the print density is a stronger linear correlation compared to the ISO brightness. Paper whiteness has a positive correlation with the ISO brightness. The print colorimetric values (lightness and chroma values) increased with increasing paper whiteness up to a certain level, after which the paper whiteness did not have a noticeable impact on its print lightness and chroma values. The print color (a* and b* values) was affected by its corresponding paper color.

The dynamic drainage, zeta potential, cationic demand, fiber morphology, ash content, and silica content of rice straw soda-anthraquinone (soda/AQ) pulps were measured to study the effects of a mechanical treatment on the drainage performance. The physical properties of handsheets prepared from each beaten sample were also analyzed. It was indicated that pulp fibers played an important role in increasing the beating degree in comparison with non-fibrous cells during refining. The dynamic drainage curve could be divided into three different stages in terms of the drainage rate, and the difference between the pulps screened-out non-fibrous cells (Pnof), and unremoved non-fibrous cells (Pf) decreased with refining. Due to the absence of a large quantity of non-fibrous cells, as the beating proceeded, the straw pulp presented an ever-increasing tendency in terms of kink index and curl index. Also, cationic demands of pulps increased linearly and the zeta potential of the fibers decreased gradually with beating. Rice straw was found to be favorable for papermaking, helping to compensate for an acute shortage of wood in China.

The effects of technical, technological, and material factors affecting the size of juvenile poplar wood chips were evaluated. Each analysis was performed on two species of poplar, namely natural poplar Populus tremula L. and plantation poplar clones Populus euramericana Serotina, and on juvenile and mature wood within each poplar species. A cutter with angular geometry was selected for the face milling: b = 55° (angle of cutting wedge), g = 15° (rake angle). The cutting conditions were a feed rate of v_f = 2.5 and 15 m·min^-1, cutting speed of v_c = 30 m·s^-1, 45 m·s^-1, and 60 m·s^-1, and the depth of cut a_p = 1 mm. An image analysis of the size of the largest and smallest fraction was performed. Most of the chips generated during the face milling of poplar wood were classified as flat grain wood. A small percentage of the generated chips could be included in the group of rod-shaped fibrous bulk particles with a considerable extension in one direction (smaller fractions generated at a feed rate of 2.5 m·min^-1, and at the finest fractions- dust generated in all of the combinations of technical and technological parameters).

Silver nanoparticles (AgNPs) were synthesized from AgNO3 using rice straw biomass as the reducing agent at room temperature via light irradiation. Full wavelength scanning with UV/Vis spectrophotometer was used to study the effect of light intensity, reaction time, and concentrations of rice straw biomass and AgNO3 during AgNPs synthesis. Surface plasmon resonance (SPR) showed that the peak wavelength of synthesized silver nanoparticles arose at 425 nm, the optimal light intensity observed was 60,000 lx, and the optimal reaction time was 140 min. The optimum concentrations of the rice straw biomass and AgNO3 used were 4 mg/mL and 2 mM, respectively. The AgNPs were characterized by X-ray diffraction (XRD) analysis. The zeta potential of AgNPs reached -21.2 mV. In addition, the AgNPs synthesized by rice straw biomass revealed antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphyloccus aureus. The inhibition rate reached about 97.17 ± 2.01% when the concentration of AgNPs solution used was 8 μg/mL. In the detection of antimicrobial effect of AgNPs and antibiotics, the antibacterial activity was found to be superior to that of antibiotics alone.