A new strategy to improve ramie degumming based on removal of the xylan branched structure

2021 ◽  
pp. 004051752110449
Author(s):  
Huihui Wang ◽  
Tong Shu ◽  
Pandeng Li ◽  
Yun Bai ◽  
Mengxiong Xiang ◽  
...  
Keyword(s):  
Removal Rate ◽  
Natural Fibers ◽  
Green Manufacturing ◽  
Operating Conditions ◽  
Ramie Fiber ◽  
Wild Type ◽  
Acetyl Xylan Esterase ◽  
Degumming Process ◽  
Main Component ◽  
Engineered Strain

Ramie fiber is known as the “king of natural fibers,” and the key to its wide application is efficient and green manufacturing. Microbial degumming has gradually become a hot area of research due to its environmental protection and mild operating conditions. However, some gummy materials remain after microbial degumming. Xylan is the main component of residual gums; its acetylated branched chains create the space barrier that makes the removal of hemicellulose difficult during ramie degumming. An acetyl xylan esterase (AXE) was obtained from Bacillus pumilus and characterized to solve this problem. Its optimum temperature and pH were 35°C and 8.0, respectively, and it had good temperature and pH stability. These properties were consistent with the conditions of ramie degumming and they laid a foundation for the application of AXE in ramie degumming. Besides, an engineered strain with a high activity of AXE was constructed successfully on the basis of the wild-type degumming strain Pectobacterium carotovorum HG-49 and used for ramie degumming. The removal rate of hemicellulose and total gums by the engineered strain increased by 4.89% and 2.53%, respectively, compared with that of the wild-type strain. Moreover, the role of this AXE in ramie degumming was further proven by X-ray diffraction and scanning electron microscopy. This study showed that AXE played an important role in the removal of hemicellulose in the degumming process of ramie fibers, thus providing a promising degumming strategy for ramie and other bast fiber plants.

scholarly journals Green degumming process of ramie fiber thermal effect and optimization

2019 ◽  
Vol 23 (4) ◽  
pp. 2447-2451 ◽  
Author(s):  
Guoliang Liu ◽  
Dan Tian ◽  
Bangze Zhou ◽  
Yumeng Zhang ◽  
Tao Xu ◽  
...  
Keyword(s):  
Natural Fibers ◽  
Weight Ratio ◽  
Raw Material ◽  
Effect Of Temperature ◽  
Ramie Fiber ◽  
Traditional Treatment ◽  
Sodium Percarbonate ◽  
Ramie Fibers ◽  
Degumming Process ◽  
Environmentally Friendly Process

Ramie is a kind of natural fibers, it requires degumming process before it can be used as a raw material for various applications. The traditional treatment uses alkali, which is not an environmentally friendly process. In this paper, ramie fibers are degummed using sodium percarbonate, which causes no any negative environmental problems, and its decomposition, hydrogen peroxide, is a clear liquid, it can be used as an oxidizer, bleaching agent and antiseptics for surface treatment of ramie fibers. Effect of temperature and concentration of sodium percarbonate on the degumming process are studied theoretically and verified experimentally. Finally an optimal degumming process is suggested for maximal weight ratio of degummed ramie fiber to raw bast.

Determination of cost-efficient cooling power range for improving the performance of internally cooled ultrasonic atomization liquid desiccant dehumidifiers

2020 ◽  
Vol 29 (9) ◽  
pp. 1260-1276
Author(s):  
Zili Yang ◽  
Lu-An Chen ◽  
Ruiyang Tao ◽  
Ke Zhong
Keyword(s):  
Power Efficiency ◽  
Removal Rate ◽  
Operating Conditions ◽  
Cooling Power ◽  
Internal Cooling ◽  
Liquid Desiccant ◽  
Improvement Rate ◽  
Ultrasonic Atomization ◽  
Internally Cooled ◽  
Cost Efficient

Liquid desiccant dehumidifiers (LDDs) can be improved by adding internal cooling. However, the addition of excessive cooling power may deteriorate the system‘s cost-efficiency, whereas the addition of insufficient cooling power leads to negligible performance improvements. The objective of this study is to determine the suitable cost-efficient cooling power range for improving the performance of internally cooled LDDs (IC-LDDs). A novel method and a set of criteria related to the moisture removal rate, cooling-power efficiency ( ηc) and coefficient of dehumidification performance from cooling power ( DCOPcooling) were proposed to determine cost-efficient cooling power. The internally cooled ultrasonic atomization liquid desiccant system (IC-UADS), together with a well-validated model based on the conservation laws of mass and energy and the sensible heat balance, was adopted to demonstrate the analysis. The results showed that, although the dehumidification performance improves with increasing cooling power, the improvement rate decreases, while ηcand DCOPcoolingdecline quickly (by 87.9%). For cost-efficient improvement, the necessary power proportion of internal cooling to the system‘s target dehumidification capacity tends to be stable, which was about 29% for the IC-UADS, and independent of the operating conditions. The results may help to determine the reasonable cooling power range for cost-efficient improvement of IC-LDDs.

scholarly journals Mechanical Properties of Boehmeria nivea Natural Fabric Reinforced Epoxy Matrix Composite Prepared by Vacuum-Assisted Resin Infusion Molding

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1311 ◽  
Author(s):  
Fabio da Costa Garcia Filho ◽  
Fernanda Santos da Luz ◽  
Lucio Fabio Cassiano Nascimento ◽  
Kestur Gundappa Satyanarayana ◽  
Jaroslaw Wieslaw Drelich ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Volume Fraction ◽  
Natural Fibers ◽  
Ramie Fiber ◽  
Resin Infusion ◽  
Lignocellulosic Fibers ◽  
Boehmeria Nivea ◽  
Fabric Composites ◽  
Epoxy Matrix Composite ◽  
Efficient Alternative

Natural lignocellulosic fibers and corresponding fabrics have been gaining notoriety in recent decades as reinforcement options for polymer matrices associated with industrially applied composites. These natural fibers and fabrics exhibit competitive properties when compared with some synthetics such as glass fiber. In particular, the use of fabrics made from natural fibers might be considered a more efficient alternative, since they provide multidirectional reinforcement and allow the introduction of a larger volume fraction of fibers in the composite. In this context, it is important to understand the mechanical performance of natural fabric composites as a basic condition to ensure efficient engineering applications. Therefore, it is also important to recognize that ramie fiber exhibiting superior strength can be woven into fabric, but is the least investigated as reinforcement in strong, tough polymers to obtain tougher polymeric composites. Accordingly, this paper presents the preparation of epoxy composite containing 30 vol.% Boehmeria nivea fabric by vacuum-assisted resin infusion molding technique and mechanical behavior characterization of the prepared composite. Obtained results are explained based on the fractography studies of tested samples.

Study on De-Nitrification of Improved Step-Feed Progress

2014 ◽  
Vol 703 ◽  
pp. 171-174
Author(s):  
Bing Wang ◽  
Yi Xiao ◽  
Shou Hui Tong ◽  
Lan Fang ◽  
Da Hai You ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Operating Conditions ◽  
Removal Mechanism ◽  
Aerobic Zone

Improved step-feed de-nitrification progress combined with biological fluidized bed was introduced in this study. The progress had good performance and capacity of de-nitrification and organic matter. The experiment result showed that the de-nitrification efficiency of the improved biological fluidized bed with step-feed process was higher than the fluidized bed A/O process under the same water quality and the operating conditions. When the influent proportion of each segment was equal, the system showed good nitrogen removal efficiency with the change of influent C/N ratio, HRT and sludge return ratio. The removal rate of TN reached up to 88.2%. It showed that the simultaneous nitrification and de-nitrification phenomenon happened in the aerobic zone. The nitrogen removal mechanism was also studied.

scholarly journals Single Amino Acid Substitutions in HXT2.4 from Scheffersomyces stipitis Lead to Improved Cellobiose Fermentation by Engineered Saccharomyces cerevisiae

2012 ◽  
Vol 79 (5) ◽  
pp. 1500-1507 ◽  
Author(s):  
Suk-Jin Ha ◽  
Heejin Kim ◽  
Yuping Lin ◽  
Myoung-Uoon Jang ◽  
Jonathan M. Galazka ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Single Amino Acid ◽  
Kinetic Properties ◽  
Wild Type ◽  
Scheffersomyces Stipitis ◽  
Content Type ◽  
Charged Amino Acids ◽  
Cellodextrin Transporter ◽  
Engineered Strain

ABSTRACTSaccharomyces cerevisiaecannot utilize cellobiose, but this yeast can be engineered to ferment cellobiose by introducing both cellodextrin transporter (cdt-1) and intracellular β-glucosidase (gh1-1) genes fromNeurospora crassa. Here, we report that an engineeredS. cerevisiaestrain expressing the putative hexose transporter geneHXT2.4fromScheffersomyces stipitisandgh1-1can also ferment cellobiose. This result suggests that HXT2.4p may function as a cellobiose transporter whenHXT2.4is overexpressed inS. cerevisiae. However, cellobiose fermentation by the engineered strain expressingHXT2.4andgh1-1was much slower and less efficient than that by an engineered strain that initially expressedcdt-1andgh1-1. The rate of cellobiose fermentation by theHXT2.4-expressing strain increased drastically after serial subcultures on cellobiose. Sequencing and retransformation of the isolated plasmids from a single colony of the fast cellobiose-fermenting culture led to the identification of a mutation (A291D) in HXT2.4 that is responsible for improved cellobiose fermentation by the evolvedS. cerevisiaestrain. Substitutions for alanine (A291) of negatively charged amino acids (A291E and A291D) or positively charged amino acids (A291K and A291R) significantly improved cellobiose fermentation. The mutant HXT2.4(A291D) exhibited 1.5-fold higherKmand 4-fold higherVmaxvalues than those from wild-type HXT2.4, whereas the expression levels were the same. These results suggest that the kinetic properties of wild-type HXT2.4 expressed inS. cerevisiaeare suboptimal, and mutations of A291 into bulky charged amino acids might transform HXT2.4p into an efficient transporter, enabling rapid cellobiose fermentation by engineeredS. cerevisiaestrains.

scholarly journals Engineering cytoplasmic acetyl-CoA synthesis decouples lipid production from nitrogen starvation in the oleaginous yeast Rhodosporidium azoricum

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Silvia Donzella ◽  
Daniela Cucchetti ◽  
Claudia Capusoni ◽  
Aurora Rizzi ◽  
Silvia Galafassi ◽  
...  
Keyword(s):  
Lipid Content ◽  
Nitrogen Starvation ◽  
Neutral Lipids ◽  
Lipid Production ◽  
Industrial Process ◽  
Wild Type ◽  
Lipid Concentration ◽  
Atp Citrate Lyase ◽  
Acetyl Coa ◽  
Engineered Strain

Abstract Background Oleaginous yeasts are able to accumulate very high levels of neutral lipids especially under condition of excess of carbon and nitrogen limitation (medium with high C/N ratio). This makes necessary the use of two-steps processes in order to achieve high level of biomass and lipid. To simplify the process, the decoupling of lipid synthesis from nitrogen starvation, by establishing a cytosolic acetyl-CoA formation pathway alternative to the one catalysed by ATP-citrate lyase, can be useful. Results In this work, we introduced a new cytoplasmic route for acetyl-CoA (AcCoA) formation in Rhodosporidium azoricum by overexpressing genes encoding for homologous phosphoketolase (Xfpk) and heterologous phosphotransacetylase (Pta). The engineered strain PTAPK4 exhibits higher lipid content and produces higher lipid concentration than the wild type strain when it was cultivated in media containing different C/N ratios. In a bioreactor process performed on glucose/xylose mixture, to simulate an industrial process for lipid production from lignocellulosic materials, we obtained an increase of 89% in final lipid concentration by the engineered strain in comparison to the wild type. This indicates that the transformed strain can produce higher cellular biomass with a high lipid content than the wild type. The transformed strain furthermore evidenced the advantage over the wild type in performing this process, being the lipid yields 0.13 and 0.05, respectively. Conclusion Our results show that the overexpression of homologous Xfpk and heterologous Pta activities in R. azoricum creates a new cytosolic AcCoA supply that decouples lipid production from nitrogen starvation. This metabolic modification allows improving lipid production in cultural conditions that can be suitable for the development of industrial bioprocesses using lignocellulosic hydrolysates.

scholarly journals The Xylanase Inhibitor TAXI-I Increases Plant Resistance to Botrytis cinerea by Inhibiting the BcXyn11a Xylanase Necrotizing Activity

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 601
Author(s):  
Silvio Tundo ◽  
Maria Chiara Paccanaro ◽  
Ibrahim Elmaghraby ◽  
Ilaria Moscetti ◽  
Renato D’Ovidio ◽  
...  
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Plant Cell Wall ◽  
Wild Type ◽  
Cell Wall Degrading Enzymes ◽  
Targeted Deletion ◽  
Plant Infection ◽  
Transgenic Lines ◽  
Xylanase Inhibitor ◽  
Main Component

During host plant infection, pathogens produce a wide array of cell wall degrading enzymes (CWDEs) to break the plant cell wall. Among CWDEs, xylanases are key enzymes in the degradation of xylan, the main component of hemicellulose. Targeted deletion experiments support the direct involvement of the xylanase BcXyn11a in the pathogenesis of Botrytis cinerea. Since the Triticum aestivum xylanase inhibitor-I (TAXI-I) has been shown to inhibit BcXyn11a, we verified if TAXI-I could be exploited to counteract B. cinerea infections. With this aim, we first produced Nicotiana tabacum plants transiently expressing TAXI-I, observing increased resistance to B. cinerea. Subsequently, we transformed Arabidopsis thaliana to express TAXI-I constitutively, and we obtained three transgenic lines exhibiting a variable amount of TAXI-I. The line with the higher level of TAXI-I showed increased resistance to B. cinerea and the absence of necrotic lesions when infiltrated with BcXyn11a. Finally, in a droplet application experiment on wild-type Arabidopsis leaves, TAXI-I prevented the necrotizing activity of BcXyn11a. These results would confirm that the contribution of BcXyn11a to virulence is due to its necrotizing rather than enzymatic activity. In conclusion, our experiments highlight the ability of the TAXI-I xylanase inhibitor to counteract B. cinerea infection presumably by preventing the necrotizing activity of BcXyn11a.

Anaerobic digestion of waste activated sludge combined with ozone post-treatment and recycling

2003 ◽  
Vol 48 (4) ◽  
pp. 61-68 ◽  
Author(s):  
A. Battimelli ◽  
C. Millet ◽  
J.P. Delgenès ◽  
R. Moletta
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Removal Rate ◽  
Operating Conditions ◽  
Cod Removal ◽  
Process Efficiency ◽  
Recycling Rate ◽  
Waste Activated Sludge ◽  
Digested Sludge ◽  
Combined Process

The aim of the study was to determine the performances of a combined ozone/anaerobic digestion system for waste activated sludge reduction. The objective was the estimation of the process efficiency and stability when keeping constant influent flow while increasing recycled chemically treated flow. The ozonation step consisted in a partial oxidation (0.16 g O3/g SS) of the anaerobic mesophilic digested sludge. Chemical treatment of digested sludge resulted in a threefold COD solubilization and a decrease of SS of 22%. Some of the advantages of digested sludge ozonation were: deodorization, better settlement and a reduction in viscosity. However there were drawbacks: foaming during ozonation and, at high ozone doses, poorer filterability. The anaerobic digestion was carried out over 6 months with an increasing recycling of ozonated flow. Suspended solids removal rate and COD removal rate were compared with initial operating conditions for the biological reactor and the whole combined process. The optimum recycling rate was 25% with increases of SS removal and COD removal of 54% and 66% respectively when considering the combined process; corresponding to a decrease of the hydraulic retention time from 24 days to 19 days.

scholarly journals A Simple Procedure for Searching Pareto Optimal Front in Machining Process: Electric Discharge Machining

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Ushasta Aich ◽  
Simul Banerjee
Keyword(s):  
Electric Discharge ◽  
Removal Rate ◽  
Simple Procedure ◽  
Operating Conditions ◽  
Machining Process ◽  
Optimum Process ◽  
Pareto Optimal ◽  
Electric Discharge Machining ◽  
Optimum Process Parameter ◽  
Pareto Optimal Front

Optimum control parameter setting in complex and stochastic type processes is one of the most challenging problems to the process engineers. As such, effective model development and determination of optimal operating conditions of electric discharge machining process (EDM) are reasonably difficult. In this apper, an easy to handle optimization procedure, weight-varying multiobjective simulated annealing, is proposed and is applied to optimize two conflicting type response parameters in EDM—material removal rate (MRR) and average surface roughness (Ra) simultaneously. A solution set is generated. The Pareto optimal front thus developed is further modeled. An inverse solution procedure is devised so that near-optimum process parameter settings can be determined for specific need based requirements of process engineers. The results are validated.

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