1,720,988 research outputs found
ABE production from yellow poplar through alkaline pre-hydrolysis, enzymatic saccharification, and fermentation
No full textABE (acetone-butanol-ethanol) was produced through alkaline pre-hydrolysis, enzymatic saccharification, and fermentation using yellow poplar as a raw material. In alkaline pre-hydrolysis, 51.1% of the biomass remained as a residue. In the main woody components, the degrees of lignin and xylan removal were 94.3 and 62.0%, respectively. A yield of 80.9% for cellulose-to-glucose and 81.2% for xylan-to-xylose were obtained by enzymatic hydrolysis. The sugar composition of enzymatic hydrolysate was 95.1 g/L of glucose and 21.4 g/L of xylose. The enzymatic hydrolysate also contained 0.5 g/L of acetic acid and 0.5 g/L of total phenolics. Furfural and 5-hydroxymethylfurfural (5-HMF) were not detected in this hydrolysate. The yellow poplar hydrolysate (YPH) from enzymatic saccharification was used for the production of ABE using Clostridium acetobutylicum and C. beijerinckii. In YPH fermentation, C. acetobutylicum produced 18.1 g/L total ABE (productivity 0.38 g/L h, and yield 0.42), and C. beijerinckii produced 12.1 g/L (productivity 0.25 g/L h, and yield 0.37). Although the ABE productivity by C. beijerinckii was slightly low, the general performance of ABE fermentation in YPH was similar to or higher than those reported previously. Therefore, alkaline pre-hydrolysis could be a very effective pretreatment step prior to enzymatic hydrolysisclos
Silaffin Peptides as a Novel Signal Enhancer for Gravimetric Biosensors
No full textApplication of biomimetic silica formation to gravimetric biosensors has been conducted for the first time. As a model system, silaffin peptides fused with green fluorescent protein (GFP) were immobilized on a gold quartz crystal resonator for quartz crystal microbalances using a self-assembled monolayer. When a solution of silicic acid was supplied, silica particles were successfully deposited on the Au surface, resulting in a significant change in resonance frequency (i.e., signal enhancement) with the silaffin-GFP. However, frequency was not altered when bare GFP was used as a control. The novel peptide enhancer is advantageous because it can be readily and quantitatively conjugated with sensing proteins using recombinant DNA technology. As a proof of concept, this study shows that the silaffin domains can be employed as a novel and efficient biomolecular signal enhancer for gravimetric biosensorsope
Identification of Escherichia coli biomarkers responsive to various lignin-hydrolysate compounds
No full textAberrations in the growth and transcriptome of Escherichia coli str. BL21(DE3) were determined when exposed to varying concentrations of ferulic acid (0.25-1 g/L), an aromatic carboxylic acid identified within lignin-cellulose hydrolysate samples. The expression of several individual genes (aaeA, aaeB, inaA and marA) was significantly induced, i.e., more than 4-fold, and thus these genes and the heat shock response gene htpG were selected as biomarkers to monitor E. coli's responses to five additional hydrolysate-related compounds, including vanillic acid, coumaric acid, 4-hydroxybenzoic acid, ferulaldehyde and furfural. While all of the biomarkers showed dose-dependent responses to most of the compounds, expression of aaeA and aaeB showed the greatest induction (5-30-fold) for all compounds tested except furfural. Lastly, the marA, inaA and htpG genes all showed higher expression levels when the culture was exposed to spruce hydrolysate samples, demonstrating the potential use of these genes as biomarkers.close4
Feasibility of a facile butanol bioproduction using planetary mill pretreatment
No full textA facile butanol bioproduction process was developed using planetary milling, and Pinus rigida wood waste as a model substrate for fermentable sugars. The use of planetary milling as the pretreatment eliminates the need for washing and transfer of the biomass prior to enzymatic hydrolysis. Moreover, using this pretreatment process resulted in the production of only 0.072 +/- 0.003 g/L soluble phenolic compounds, a concentration that was not inhibitory towards Clostridium beijerinckii NCIMB 8052. As the milling was performed in a compatible buffer (50 mM acetate, pH 4.8), the enzymatic hydrolysis step was initiated by simply adding the cellulase cocktail powder directly to pretreated biomass without washing the biomass or exchanging the buffer, resulting in a glucose yield of 31 g/L (84.02%). Fermentation of the hydrolysate samples by C. beijerinckii NCIMB 8052 gave slightly better butanol yields than cultures grown in a typical lab media (P2), with final concentrations of 6.91 and 6.66 g/L, respectively. (C) 2015 Elsevier Ltd. All rights reservedopen
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Improved Sugar Production by Optimizing Planetary Mill Pretreatment and Enzyme Hydrolysis Process
Get PDFThis paper describes an optimization of planetary mill pretreatment and saccharification processes for improving biosugar production. Pitch pine (Pinus rigida) wood sawdust waste was used as biomass feedstock and the process parameters optimized in this study were the buffering media, the milling time, the enzyme quantity, and the incubation time. Glucose yields were improved when acetate buffer was used rather than citrate buffer. Initially, with each process variable tests, the optimal values were 100 minutes of milling, an enzyme concentration of 16 FPU/g-biomass, and a 12-hour enzymatic hydrolysis. Typically, interactions between these experimental conditions and their effects on glucose production were next investigated using RSM. Glucose yields from the Pinus rigida waste exceeded 80% with several of the conditions tested, demonstrating that milling can be used to obtain high levels of glucose bioconversion from woody biomass for biorefinery purposesopen
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Thermostabilization of Candida antarctica lipase B by double immobilization:. Adsorption on a macroporous polyacrylate carrier and R1 silaffin-mediated biosilicification
No full textA large improvement in the thermostability of Candida antarctica lipase B (CALB) was achieved through double immobilization, i.e., physical adsorption and R1 silaffin-mediated biosilicification. The C-terminus of CALB was fused with the R1 silaffin peptide for biosilicification. The CALB-R1 fusion protein was adsorbed onto a macroporous polyacrylate carrier and then subsequently biosilicified with tetramethyl orthosilicate (TMOS). After R1 silaffin-mediated biosilicification, the double-immobilized CALB-R1 exhibited remarkable thermostability. The T-50(60) of the double-immobilized CALB-R1 increased dramatically from 45 to 72 degrees C and that was 27, 13.8, 9.8 and 9.9 degrees C higher than the T-50(60) values of free CALB-R1, CALB-R1 adsorbed onto a resin, commercial Novozym 435, and Novozym 435 treated with TMOS, respectively. In addition, the time required for the residual activity to be reduced to half (t(1/2)) of the double immobilized CALB-R1 elevated from 12.2 to 385 min, which is over 30 times longer life time compared free CALB-R1. The optimum pH for biosilicification was determined to be 5.0, and the double-immobilized enzyme showed much better reusability than the physically adsorbed enzyme even after 6 repeated reuses. This R1-mediated biosilicification approach for CALB thermostabilization is a good basis for the thermostabilization of industrial enzymes that are only minimally stabilized by protein engineering.ope
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