Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Effects of surfactant micelles and surfactant-coated nanospheres on methane hydrate growth pattern
No full textSurfactants have been reported to promote the gas hydrate formation by changing the hydrate formation pattern. In this work, methane hydrate formation was carried out in glass tubes to study the effects of the existence of surfactant micelles on methane hydrate growth pattern. For comparison, surfactants could and could not form micelles at hydrate formation temperature were used, which were sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), respectively. SDS led to obvious upward hydrate growth on the reactor sidewall (cover factors 2.8-3.7), while SDBS resulted in obviously less extent of upward hydrate growth (cover factors 1.8-2.6) due to the micelle effect. When SDS-coated polystyrene nanospheres were used, SDS existed in the reaction solution in the form of mimic micelles and consequently much less extent of upward hydrate growth was achieved (cover factors 1.8-2.3). When SDBS was used together with SDS at non-micelle forming condition, prominent upward hydrate growth was obtained (cover factors 2.7-3.3). (C) 2016 Elsevier Ltd. All rights reserved
Improving the Secretory Expression of an - Galactosidase from Aspergillus niger in Pichia pastoris
No full textalpha-Galactosidases are broadly used in feed, food, chemical, pulp, and pharmaceutical industries. However, there lacks a satisfactory microbial cell factory that is able to produce alpha-galactosidases efficiently and cost-effectively to date, which prevents these important enzymes from greater application. In this study, the secretory expression of an Aspergillus niger alpha-galactosidase (AGA) in Pichia pastoris was systematically investigated. Through codon optimization, signal peptide replacement, comparative selection of host strain, and saturation mutagenesis of the P1' residue of Kex2 protease cleavage site for efficient signal peptide removal, a mutant P. pastoris KM71H (Mut(s)) strain of AGA-I with the specific P1' site substitution (Glu to Ile) demonstrated remarkable extracellular a-galactosidase activity of 1299 U/ ml upon a 72 h methanol induction in 2.0 L fermenter. The engineered yeast strain AGA-I demonstrated approximately 12-fold higher extracellular activity compared to the initial P. pastoris strain. To the best of our knowledge, this represents the highest yield and productivity of a secreted alpha-galactosidase in P. pastoris, thus holding great potential for industrial application
Unsubstituted Benzodithiophene-Based Conjugated Polymers for High-Performance Organic Field-Effect Transistors and Organic Solar Cells
No full textUnsubstituted benzo[1,2-b:4,5-b']dithiophene (BDT) was used to construct a high-performance conjugated polymer with 5,6-difluoro-4,7-bis[4-(2octyldodecyl)thiophene-2-yl]benzo[c] [1,2,5] thiadiazole (DTFFBT), named PBDTDTFFBT. The polymer shows the low-lying highest occupied molecular orbital (HOMO) energy level (-5.40 eV) and a broad absorption spectra with strong vibronic absorption peak. Pure polymer films exhibit good crystallinity and edge-on orientation, partially attributed to the BDT units without any side chains, and as a result, the corresponding thin-film transistor showed excellent hole mobility over 1 cm(2) V-(1) s(-1). Interestingly, a well-distributed nanofibrillar polymer aggregation with face-on orientation was obviously formed when blending with PC71BM, which was in favor of the charge transportation. Consequently, the bulk heterojunction polymer solar cells based on the blends showed high power conversion efficiency of 9.29% with large short-current density (14.56 mA cm(-2)) and high fill factor (0.751) without any process additives or thermal annealing
A balanced cation exchange reaction toward highly uniform and pure phase FA(1-x)MA(x)PbI(3) perovskite films
No full textUnlike traditional MAPbI(3), methods for large scale fabrication of high quality FA based perovskite films are still lacking. In this paper, the organic cation exchange temperature is optimized toward the formation of highly uniform FA based perovskite films. Under optimized conditions, the cation diffusion speed within the perovskite film is extremely enhanced and the time constant is reduced similar to 20 times. The shortened dipping time and mild reaction conditions can efficiently restrict the undesirable phase transition and preserve the film morphology. Fundamental insight into this solid-liquid reaction has been obtained by combining photophysical, XRD and SEM characterizations. The optimized FA(x)MA(1-x)PbI(3) with x approximate to 0.75 presents the highest efficiency of 15.5% with less hysteresis
Renewable chemical feedstocks from peanut shell liquefaction: Preparation and characterization of liquefied products and residue
No full textThe objective of this investigation is to liquefy peanut shell for the preparation of aromatic polyol-rich products. The influences of reaction parameters are discussed. It is found that, compared to single-solvent, the mixture of polyethylene glycol and glycerol as solvents shows higher liquefaction efficiency. And the maximum liquefaction yield of 98.7 wt % can be achieved when the sulfuric acid content, mass ratio between polyethylene glycerol, glycerol, and peanut shell powder, liquefaction temperature, and time are 17 wt % (relative to peanut shell), 8/2/1, 150 degrees C, and 2 h, respectively. Furthermore, the solubility test result indicates that the liquefied products are fully soluble in the water and polyol. Meanwhile, the properties of the peanut shell and liquefaction residue were analyzed by means of attenuated total reflectance-Fourier transform infrared spectroscope, thermal gravity analysis, and scanning electron microscope. The polysaccharide is degraded by the cleaving of C-O bond, and the lignin is decomposed by leaving the dominant linkages including beta-O-4, 4-O-5, and dibenzodioxocin units. The fibers in the peanut shell are broken, and the nondegraded components in the residue lost their network structure. (C) 2016 Wiley Periodicals, Inc
