Hydrolysis Of Fibers Research Articles

Structural characterization of corn fiber hemicelluloses extracted by organic solvent and screening of degradation enzymes

An integrated treatment coupling peracetic acid delignification, dimethyl sulfoxide extraction, and ethanol precipitation were performed to isolate hemicellulose from de-starched corn fiber. Based on chemical composition, molecular weight distribution, methylation, and nuclear magnetic resonance spectroscopy, it is proposed that hemicelluloses in corn fiber were composed of two polysaccharides, glucuronoarabinoxylan (about 80 %) and xyloglucan (about 20 %). Xylose (about 46 %) and arabinose (about 32 %) were the main components in glucuronoarabinoxylan. More than half of the xylose units in the glucuronoarabinoxylan backbone chain were substituted at O-2 and/or O-3 by various monomers or oligomeric side chains. Based on structure analysis, five hemicellulases were selected and added to Penicillium oxalicum MCAX enzymes for enzymatic hydrolysis of corn fiber. The results showed that the addition of hemicellulases increased the sugar yield of corn fiber. These results demonstrate the effectiveness of enzyme consortium constructed by elucidating the chemical structure of hemicellulose in corn fiber for the degradation of corn fiber and also provide a general solution for the rational construction of targeted and efficient enzyme systems for the degradation of lignocellulosic biomass.

Preparation of Cellulose Hydrogels and Hydrogel Nanocomposites Reinforced by Crystalline Cellulose Nanofibers (CNFs) as a Water Reservoir for Agriculture Use

An effective strategy for the management of available water and fertilizers is imperative to improve agricultural production and food quality, including releasing them sustainably to the soil and plants. Polymeric hydrogels with three-dimensional (3D) networks can absorb ample water and soluble fertilizers without network dissolution. Subsequently, the absorbed water and fertilizers can be released to arid and semi-arid agricultural land to furnish enough moisture and nutrients for plant growth. In this study, carboxymethyl cellulose sodium salt (NaCMC)- and hydroxyethyl cellulose (HEC)-based hydrogels have been synthesized using citric acid (CA) as a crosslinker. The Fourier transform infrared (FTIR) spectroscopy study revealed the formation of hydrogels with porous structures depicted by field emission scanning electron microscopy images. The prepared hydrogels have shown a remarkable swelling ratio of ∼1070% for the hydrogel prepared using NaCMC/HEC: 2/1 and ∼840% for NaCMC/HEC: 3/1 and a reduction in the swelling ratio with increasing crosslinking density. Moreover, crystalline (shown by X-ray diffraction) cellulose nanofibers (CNFs: ∼600 nm), prepared by acid (H2SO4) hydrolysis of cotton fibers, have been used to prepare hydrogel nanocomposites. The evaluation of hydrogel nanocomposites’ mechanical properties (universal testing matching test) depicted an improved tensile strength (16.27 MPa using 0.7% CNFs) compared to that of the hydrogel without CNFs. The soil burial test for biodegradation study of prepared hydrogels revealed soil degradation of hydrogel, confirmed by FTIR analysis and visual appearance. The current study provides comprehensive data establishing the potential of hydrogels for agriculture applications.

Oxidized Dopamine Acrylamide Primer to Achieve Durable Resin-Dentin Bonding.

The durability of the resin-dentin bonding interface is a key issue in clinical esthetic dentistry. Inspired by the extraordinary bioadhesive properties of marine mussels in a wet environment, we designed and synthetized N-2-(3,4-dihydroxylphenyl) acrylamide (DAA) according to the functional domain of mussel adhesive proteins. DAA's properties of collagen cross-linking, collagenase inhibition, inducing collagen mineralization in vitro, and as a novel prime monomer for clinical dentin adhesion use, its optimal parameters, and effect on the adhesive longevity and the bonding interface's integrity and mineralization, were evaluated in vitro and in vivo. The results showed that oxide DAA can inhibit the activity of collagenase and cross collagen fibers to improve the anti-enzymatic hydrolysis of collagen fibers and induce intrafibrillar and interfibrillar collagen mineralization. As a primer used in the etch-rinse tooth adhesive system, oxide DAA can improve the durability and integrity of the bonding interface by anti-degradation and mineralization of the exposed collagen matrix. Oxidized DAA (OX-DAA) is a promising primer for improving dentin durability; using 5% OX-DAA ethanol solution and treating the etched dentin surface for 30 s is the optimal choice when used as a primer in the etch-rinse tooth adhesive system.

Effects of wood fiber on the properties of silicoaluminophosphate geopolymer

Silicoaluminophosphate geopolymer is an important class of inorganic cementitious material, which attracts increasing attention due to the excellent mechanical properties, high thermal resistance and low dielectric properties. However, like most of the pristine or unreinforced cement based materials, silicoaluminophosphate geopolymer still suffers from brittle failure, which seriously limits its popularization and application. Based on the characteristics that silicoaluminophosphate geopolymer is almost a Ca-free material forming in acidic environment and driving by the demands of low carbon, environmental friendly and low cost, this paper adopts wood fiber as a reinforcing material to improve the toughness of silicoaluminophosphate geopolymer. Results show that the incorporation of wood fiber can effectively reduce the brittleness and increase the fracture toughness of silicoaluminophosphate geopolymer by the excellent bonding performance between reaction products and wood fiber. However, the addition of wood fiber is unfavorable to the setting and hardening behaviour, reaction degree and compressive strength of silicoaluminophosphate geopolymer. Although the hydrolysis of wood fiber in acidic environment results in some local defects on its surface, these defects have little effect on the improvement of silicoaluminophosphate geopolymers toughness due to the repairing effect of reaction products.

Continuous succinic acid production from corn fiber hydrolysate by immobilized Actinobacillus succinogenes in a hollow fiber membrane packed‑bed biofilm reactor

Succinic acid is one of the most useful intermediate chemicals that can be produced in a biorefinery approach. In this study, Actinobacillus succinogenes was immobilized to produce succinic acid using non-detoxified corn fiber hydrolysate (CFH) and a control mimicking the sugars in CFH. Tests were carried out in a hollow fiber membrane packed-bed biofilm reactor (HFM–PBR) operated in a continuous mode. Under steady-state conditions, the bioconversion process was characterized in terms of sugar consumption, succinic acid and other organic acid production. Steady states were obtained at dilution rates of 0.025, 0.05, 0.075, 0.1, 0.2, and 0.3 h−1. The optimal results were achieved at the dilution rate of 0.05 h−1 and recirculation rate of 50 ml/min with a maximum succinic acid concentration, yield and productivity of 31.1 g/L, 0.61 g/g and 1.56 g/L h, respectively, when control was used. Succinic acid concentration, yield and productivity of 23.4 g/L, 0.51 g/g and 1.17 g/L h, respectively, were obtained when CFH was used. Productivity in the HFM–PBR was between 1.3 and 1.9 times higher than productivities for succinic acid production from CFH stated in the literature. The results demonstrated that immobilized A. succinogenes has the potential for effective conversion of an inexpensive biomass feedstock to succinic acid. Furthermore, the process has the potential to serve as a means for value-added chemical biomanufacturing in an integrated corn biorefinery.

Abatement of microfibre pollution and detoxification of textile dye - Indigo by engineered plant enzymes.

Microfibres (diameter <5 mm) and textile dyes released from textile industries are ubiquitous, cause environmental pollution, and harm aquatic flora, fauna, animals and human life. Therefore, enzymatic abatement of microfibre pollution and textile dye detoxification is essential. Microbial enzymes for such application present major challenges of scale and affordability to clean up large scale pollution. Therefore, enzymes required for the biodegradation of microfibres and indigo dye were expressed in transplastomic tobacco plants through chloroplast genetic engineering. Integration of laccase and lignin peroxidase genes into the tobacco chloroplast genomes and homoplasmy was confirmed by Southern blots. Decolorization (up to 86%) of samples containing indigo dye (100 mg/L) was obtained using cp-laccase (0.5% plant enzyme powder). Significant (8-fold) reduction in commercial microbial cellulase cocktail was achieved in pretreated cotton fibre hydrolysis by supplementing cost effective cellulases (endoglucanases, ß-glucosidases) and accessory enzymes (swollenin, xylanase, lipase) and ligninases (laccase lignin peroxidase) expressed in chloroplasts. Microfibre hydrolysis using cocktail of Cp-cellulases and Cp-accessory enzymes along with minimal dose (0.25% and 0.5%) of commercial cellulase blend (Ctec2) showed 88%-89% of sugar release from pretreated cotton and microfibres. Cp-ligninases, Cp-cellulases and Cp-accessory enzymes were stable in freeze dried leaves up to 15 and 36 months respectively at room temperature, when protected from light. Use of plant powder for decolorization or hydrolysis eliminated the need for preservatives, purification or concentration or cold chain. Evidently, abatement of microfibre pollution and textile dye detoxification using Cp-enzymes is a novel and cost-effective approach to prevent their environmental pollution.

Effect of static magnetic field treatment on γ-aminobutyric acid content and sensory characteristics of germinated brown rice cake

This study aimed to improve γ-aminobutyric acid (GABA) content and sensory characteristics of brown rice (BR) cake by static magnetic field (SMF)-assisted germination. BR was pre-treated by SMF (10 mT, 60 min, 25 °C), germinated for 36 h, and then germinated BR (GBR) was used to prepare rice cake. The optimal formula was: 60 % GBR, 40 % white rice, 1 % yeast, 20 % sugar, and 55 % water. SMF significantly increased the GABA content by stimulating glutamate decarboxylase, with the values increasing from 28.17 to 32.43 mg/100 g and from 2.50 to 6.27 mg/100 g in GBR (36 h) and GBR cake, respectively. SMF also altered the swelling power and water solubility of GBR flour by promoting the hydrolysis of starch, protein, and fiber, thus improving the texture, flavor, and storage stability of GBR cake. Overall, SMF could be a prospective technique for improving the nutritional and sensory qualities of whole-grain food.

Agriculture Waste as Slow Carbon Releasing Source of Mixotrophic Denitrification Process for Treating Low C/N Wastewater

Mixotrophic denitrification has showed great potential for treating wastewater with a low C/N ratio. Mixotrophic denitrification is the process combining autotrophic denitrification and heterotrophic denitrification in one system. It can compensate the disadvantage of the both denitrifications. Instead of using sodium acetate and glucose as carbon source for the heterotrophic denitrification, agriculture solid wastes including rice straw (RS), wheat straw (WS), and corncob (CC) were employed in this study to investigate their potential as carbon source for treating low C/N wastewater. The carbon releasing pattern of the three carbon rich materials has been studied as well as their capacity in denitrification. The results showed that the highest denitrification occurred in the corncob system which was 0.34 kg N/(m3·d). Corncob was then selected to combine with sulfur beads to build the mixotrophic denitrification system. The reactor packed with sulfur bead on the top and corncob on the bottom achieved 0.34 kg N/(m3·d) denitrification efficiency, which is higher than that of the reactor packed with completely mixed sulfur bead and corncob. The autotrophic denitrification and heterotrophic denitrification were 42.2% and 57.8%, respectively. The microorganisms in the sulfur layer were Thermomonas, Ferritrophicum, Thiobacillus belonging to autotrophic denitrification bacteria. Kouleothrix and Geothrix were mostly found in the corncob layer, which have the function for fiber hydrolysis and denitrification. The study has provided an insight into agriculture solid waste application and enhancement on denitrification of wastewater treatment.

Interacción molecular de fructanos lineales y ramificados de distintos tamaños con levansacarasa e inulinsacarasa de Lactobacillus gasseri: modelado y análisis computacional

Human beings consume probiotics and prebiotics because of the health benefits they provide. Lactobacillus gasseri is a probiotic microorganism native to humans which produces glycolytic enzymes directed at the hydrolysis of soluble fibers as prebiotic fructans. In this work, levansucrase (LevG) and inulosucrase (InuGB) from L. gasseri were used to predict the ability of L. gasseri to interact with linear and branched fructans prebiotics (inulin and agavins). AlphaFold and SWISS-MODEL were the servers used for tertiary structure prediction of LevG and InuGB, and fructans with different degrees of polymerization (DP2, DP4 DP6, DP8, DP12 and DP20) were used to generate ligand-enzyme molecular dockings by AutodockVina, GlycoTorchVina, and Autodock FR software. The best affinity energies obtained by molecular docking were obtained with agavin and inulin with a DP of 6 and 8 units. Aspartic acid, glutamic acid, asparagine and arginin are the main amino acids involved in the interaction with these substrates. At the same time, the binding pocket shows hydrophilic characteristics; GlycoTorchVina was the best software for protein-ligand docking. These results demonstrate the ability of L. gasseri enzymes to interact with different molecular structures of fructans; levansucrase with better affinity to agavin and inulosucrase with better affinity to inulin. The above helps to understand the structure-functionality relationship of the prebiotic effect, both in symbiotic formulations and in the human digestive tract.

Metataxonomic characterization of an autochthonous and allochthonous microbial consortium involved in a two-stage anaerobic batch reactor applied to hydrogen and methane production from sugarcane bagasse

Enzymatically pre-treated sugarcane bagasse (SCB) was used as substrate for sequential production of hydrogen (H2) and methane (CH4). In stage I, SCB was used by autochthonous bacteria, such as Enterococcus (42.4 % relative abundance) and Paraclostridium (16.8 %) for H2 production (166.8 mL H2/L), while the metabolites accumulated at the end of this stage (9140.5 mg HAc/L) were used by allochthonous inoculum for CH4 production (870.8 mL CH4/L) in stage II. In stage II, hydrogenotrophic (Methanoculleus, 49.1 %) and acetoclastic (Methanosaeta, 15.5 %) archaeal genera were identified and considered important to maintain low H2 pressure in the system. According to gene inference, the hydrolysis of the SCB fiber was performed in both stages, as potential β-glucosidase and 1,4-β-xylosidase encoding genes were predicted. However, the energy metabolism of microbial populations differed, as potential genes involved in CH4 metabolism were predominant in phase II (39.0 %).

Hydrothermal aging of fire‐protective fabrics

AbstractFire‐protective fabrics made from high‐performance fibers are available to provide protection from various hazardous conditions such as extreme heat and flame. However, these fabrics are often exposed to other deteriorating conditions, including moisture. It is a concern for user's safety as some high‐performance fibers are sensitive to hydrolysis. This study exposed eight fire‐protective fabrics corresponding to typical blends used in firefighter protective suit outer shells to accelerated hydrothermal aging. They were immersed in water at different temperatures between 60 and 95°C for up to 1200 h. After exposure to hydrothermal aging, some fabrics exhibited a significant loss in tensile strength without any morphological changes. Based on results from energy‐dispersive X‐ray spectroscopy and pH measurements of the aging water, the larger loss in strength experienced by the para‐aramid/PBI fiber‐based fabrics can be related to the high amount of sulfur measured in the PBI fibers, contributing to an acceleration of the para‐aramid fiber's hydrolysis in acidic conditions. Hydrothermal aging also appears to affect the water‐repellent finish of some fabrics. The study provides an insight into the effect of a generally ignored hazard, that is, moisture, on the long‐term performance of fire‐protective fabrics.

Foxtail millet (Setaria italica L.) silage compared peanut vine hay (Arachis hypogaea L.) exhibits greater feed efficiency via enhancing nutrient digestion and promoting rumen fermentation more efficiently in feedlotting lambs

Foxtail millet (Setaria italica L.) is an important alternative crop plant that is cultivated in Northern China. To explore its forage-use potential, a feeding trial of 60 healthy male feedlotting lambs weighing 23 ± 0.36 kg was conducted to determine the effects of replacing peanut vine hay (PVH) with different ratios (0%, 20%, 60%, and100%) of foxtail millet silage (FMS) as forage in rations on growth performance, nutrient digestibility, rumen fermentation characteristics, and bacterial community. The feeding trial was completed in two stages (Stage 1: days 1–42, forage: concentrate = 25:75; Stage 2: days 43–84, forage: concentrate = 20:80). The results show that dry matter intake (DMI) and average daily gain (ADG) increased linearly with the inclusion level of FMS in the diet (P < 0.05). Increasing the FMS replacement of PVH in rations quadratically increased the nutrient digestibility of dry matter, organic matter, crude protein and ether extract (P < 0.01) during the two stages, but the improvement of neutral detergent fiber (NDF) in response to FMS inclusion was observed during stage 2 (P < 0.01) instead of stage 1. Increasing the forage inclusion level of FMS linearly increased the digestibility of acid detergent fiber (ADF) at two stages (P < 0.05). Regarding rumen fermentation characteristics, increasing the FMS replacement of PVH in rations decreased rumen pH and linearly increased microbial crude protein (MCP) for the two stages (P < 0.05) and linearly increased NH3-N and total volatile fatty acid (VFA) (P < 0.05) during stage 2 instead of stage 1. Regarding rumen VFA pattern, increasing the FMS replacement of PVH in rations increased molar propionate proportion and remarkably decreased the acetate: proportion ratio after lamb feeding, suggesting that rumen fermentation shifted to glucogenic propionate production. Furthermore, the rumen contents of each treatment were subjected to high-throughput sequencing analysis of 16 S rRNA genes in the V3-V4 hypervariable region; here, increasing the FMS replacement of PVH in the rations did not change the alpha diversity indexes, except for the Simpson index, including Chao1, ACE, and OTUs in rumen, while increasing the FMS level in the rations linearly increased the Simpson index (P < 0.01). Increasing the FMS replacement of PVH in the rations did not alter the relative abundance of the major bacteria phyla, nor most of the major genera of rumen in lambs, except for an increasing trend in Proteobacteria. Increasing the FMS replacement of PVH in rations numerically increased starch hydrolysis bacteria, including Prevotella (P = 0.06) and Selenomonas (P = 0.05), while it linearly decreased fiber hydrolysis bacteria involved Ruminococcus and unclassified_Ruminococcaceae (P < 0.05), with numerical improvement occurring in unclassified_Lachnospiraceae (P = 0.11) in the rumen. In brief, increasing the FMS replacement of PVH in rations exhibited greater feed efficiency with increased nutrient digestibility, promoting the total VFA production as available energy in the rumen of feedlotting lambs. Rumen fermentation shifted toward glucogenic propionate production in response to dietary FMS inclusion, and this shift was found to be associated with the increased growth abundance of Prevotella and Selenomonas and the inhibition of Ruminococcus in the rumen.

Concept for the Use of Cotton Waste Hydrolysates in Fermentation Media for Biofuel Production

Currently, most cotton textile waste is sent to landfill. However, due to the use of synthetic additives and the chemical treatment of cotton fibers, cotton textile waste is difficult to biodegrade. Cotton textile waste can also be subjected to material recycling, or to incineration/gasification to produce energy. Here, we present the optimization of acid hydrolysis of cotton yarn fibers for glucose efficiency. The cotton yarn hydrolysates showed great potential for replacing simple sugar solutions in fermentation media. The highest glucose concentration was obtained in the hydrolysates of cotton yarn hydrolyzed in a 2% solution of sulfuric acid or phosphoric acid at 140–160 °C for 2 h. After 2 h of hydrolysis at 140 °C with 2% H3PO4, the concentration of glucose in the cotton yarn hydrolysate (13.19 g/L) increased fivefold compared with cotton yarn treated under the same conditions with H2SO4 (2.65 g/L). The structural modifications in the solid residues after acid hydrolysis were analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR), and Raman spectroscopy. The SEM images, IR spectra, and Raman spectra revealed that the most significant changes in the morphology of the fibers occurred when the process was carried out at high temperatures (≥140 °C). Better growth of the yeast strains Saccharomyces cerevisiae Ethanol Red and Saccharomyces cerevisiae Tokay ŁOCK0204 was observed in the medium containing phosphoric acid hydrolysate. The maximum methane yield of 278 dm3/kgVS and the maximum hydrogen yield of 42 dm/kgVS were reported for cotton yarn waste after pretreatment with H3PO4. This might have been linked to the beneficial effect of phosphorus, which is a key nutrient for anaerobic digestion. The proposed hydrolysis method does not generate fermentation inhibitors.

Steering the formation of cellobiose and oligosaccharides during enzymatic hydrolysis of asparagus fibre

The enzymatic conversion of cellulosic-rich waste streams of white asparagus into cellobiose and cello-oligosaccharides (COS) is proposed for producing a natural carrier agent. The enzyme cocktail ‘Celluclast’ was used to steer towards maximum conversion and minimum formation of monosaccharides to obtain an enzymatic hydrolysate with a high glass transition temperature (Tg). Different enzyme loadings and hydrolysis times were tested in combination with a sodium hydroxide pre-treatment of the asparagus fibre. A loading of 700 nkat/g substrate and 7 h of hydrolysis time resulted in the best yield/purity combination, namely a conversion of 36 g/100 g cellulose with 81% celllobiose/COS. The same hydrolysis conditions were tested in a larger bench-scale experiment (conversion of 45 g/100 g cellulose) and the soluble hydrolysates were concentrated and spray-dried. The high Tg (108 °C) of the spray-dried hydrolysates of asparagus fibre proves its potential usage as a carrier agent for spray drying.

Sustainable Alkaline Hydrolysis of Polyester Fabric at Low Temperature.

High crystallinity leads to low hydrophilicity of fabric made of (poly(ethylene terephthalate)) fibers (PET) causing problems in finishing, washing, and dyeing processes. To improve these properties, the surface of PET fibers is usually modified by hydrolysis. Alkaline hydrolysis is a conventional process usually performed at a temperature higher than 100 °C for more than 1 h. However, the use of strong alkali and high processing temperatures (>100 °C) can lead to fabric damage and a negative impact on the environment. Therefore, in this paper, the possibility of hydrolysis of the PET fibers in the fabric in a sustainable, energy-efficient process was researched. The influence of low temperature (60–100 °C) and an accelerator (a cationic surfactant HDTMAC) to PET alkaline hydrolysis was studied through weight loss, the loss in breaking force, and fiber morphology. The kinetics of PET dissolution in 1.5 mol cm−3 NaOH at low temperature with and without the addition of HDTMAC was determined and the activation energy was calculated according to the theoretical model. It has been confirmed that PET hydrolysis can be carried out in 1.5 mol cm−3 NaOH with the addition of HDTMAC as an accelerator at 80 °C for 10 min. This process is more economically and energetically acceptable than the conventional process, and is therefore more sustainable.

A study of pure hydrolysis of carbon fibre reinforced polyamide 6 composites tested under mode I loading

This paper focuses on the durability of carbon/polyamide 6 thermoplastic composites subjected to hydrolytic aging and tested under mode I static crack growth loading. In this study, aging was performed at temperatures ranging from 100 to 140 °C for durations up to 3 months in oxygen-free water. Results show that following wet aging the fracture toughness (energy release rate) decreases significantly, from an unaged value of 3.4 kJ/m2 down to values below 1 kJ/m2 after extensive degradation. This decrease was associated with a change from ductile to brittle behaviour, which allowed a critical molar mass M’c, to be determined for the first time on long carbon fibre reinforced composites.

Corn fiber as a biomass feedstock for production of succinic acid

The selection of an economical carbon source is a fundamental parameter to establish a successful industrial succinic acid (SA) bioprocess. In this work, corn fiber (CF), a renewable and an inexpensive source of carbohydrates, was successfully used for bioproduction of SA. Optimized liquid hot water (LHW) pretreatment followed by enzymatic hydrolysis were used to obtain corn fiber hydrolysate (CFH). Results in batch fermentation with Actinobacillus succinogenes showed that a control solution mimicking CFH produced 28.7 g/L of SA with a yield of 0.67 g SA/g sugars, while fermentation of CFH produced 27.8 g/L of SA with a yield of 0.61 g SA/g sugars. It was found that culture pH was a critical factor affecting SA production. In sodium acetate buffered media, SA was the major end-product with lower levels of acetic acid (AA) and formic acid (FA). When unbuffered media was used, lactic acid (LA) and ethanol were also detected.

Influence of Submicron Fibrillated Cellulose Fibers from Cotton on Hydration and Microstructure of Portland Cement Paste.

This paper reports the influence of submicron hydrophilic fibers on the hydration and microstructure of Portland cement paste. Submicron fibrillated cellulose (SMC) fibers was prepared by the acid hydrolysis of cotton fibers in H2SO4 solution (55% v/v) for 1.5 h at a temperature of 50 °C. The SMC fibers were added into cement with a dosage of 0.03 wt.%, and the effect of SMC on the hydration and microstructure of cement paste was investigated by calorimeter analysis, XRD, FT-IR, DSC-TG, and SEM. Microcrystalline cellulose (MCC) fibers were used as the contrast admixture with the same dosage in this study. The results show that the addition of SMC fibers can accelerate the cement hydration rate during the first 20 h of the hydration process and improve the hydration process of cement paste in later stages. These results are because the scale of SMC fibers more closely matches the size of the C-S-H gel compared to MCC fibers, given that the primary role of the SMC is to provide potential heterogeneous nucleation sites for the hydration products, which is conducive to an accelerated and continuous hydration reaction. Furthermore, the induction and bridging effects of the SMC fibers make the cement paste microstructure more homogeneous and compact.

The improved resistance against the degradation of sisal fibers under the environment of cement hydration by surface coating of graphene oxide (GO) based membranes

Natural fibers with low cost and sustainability can improve the cracking resistance of cement composites. However, the degradation of natural fibers in cement composites is the prime concern for their practical application. In this research, graphene oxide (GO) based membranes with selective permeability were coated on the surface of sisal fibers via a simple dip-coating method to improve their corrosion resistance. The uniformity and morphology of the GO-based membranes on the surface of sisal fibers were first characterized. Then, the effects of GO-based membranes on the degradation behavior (alkaline hydrolysis and mineralization) of sisal fibers were systematically investigated macroscopically and microscopically using both qualitative and quantitative analysis. The results showed that GO-based membranes can act as the protective layer of sisal fibers thus mitigating the degradation process. This research would provide a novel way to extend the long-term service life of natural fibers in cement composites.

Combined hydrothermal pre-treatment and enzymatic hydrolysis of corn fibre: Production of ferulic acid extracts and assessment of their antioxidant and antiproliferative properties

Ferulic acid may be used as a nutraceutical ingredient or as a substrate to produce bio-vanillin. There is an increasing market demand for ferulic acid obtained from natural sources such as low-cost agro-industrial by-products, due to its potential applications as nutraceutical ingredient and as a substrate to produce bio-vanillin. This work aims to study ferulic acid recovery from corn fibre (one of the most abundant natural sources of ferulic acid), involving an integrated process of hydrothermal pre-treatment followed by enzymatic hydrolysis. The objective is primarily to produce natural extracts with a maximum ferulic acid recovery yield, but it is also to assess their antioxidant and antiproliferative properties and their cytotoxicity.Different commercial enzyme preparations were tested for release of ferulic acid from corn fibre. The best results were obtained for Ultraflo ®XL in a concentration of 2 % (wenzyme preparation/w dry corn fibre) at a pH of 5 and at 55 °C, presenting a recovery yield of esterified ferulic acid of 7.83 ± 1.35 % (wrecovered ferulic acid/wtotal esterified ferulic acid), which corresponds to 0.13 ± 0.02 % (wferulic acid/w dry corn fibre). When using a hydrothermal pre-treatment at a temperature of 140 °C for 40 min, prior to the use of the same enzymatic hydrolysis procedure, the recovery yield of esterified ferulic acid increased to 28.94 ± 2.40 % (w recovered ferulic acid/ wtotal esterified ferulic acid), which corresponds to 4.9 ± 0.3 % (wferulic acid/wdry corn fibre). The use of this pre-treatment leads not only to the highest yield of ferulic acid, but also to the lowest concentration of furfural and hydroxymethylfurfural, without the formation of formic and levulinic acid (not detected). All pre-treatments tested led to an improved quality of the extract in terms of bioactivity.