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1.
Genes (Basel) ; 15(6)2024 Jun 13.
Article in English | MEDLINE | ID: mdl-38927711

ABSTRACT

The high-throughput proteomics data generated by increasingly more sensible mass spectrometers greatly contribute to our better understanding of molecular and cellular mechanisms operating in live beings. Nevertheless, proteomics analyses are based on accurate genomic and protein annotations, and some information may be lost if these resources are incomplete. Here, we show that most proteomics data may be recovered by interconnecting genomics and proteomics approaches (i.e., following a proteogenomic strategy), resulting, in turn, in an improvement of gene/protein models. In this study, we generated proteomics data from Leishmania donovani (HU3 strain) promastigotes that allowed us to detect 1908 proteins in this developmental stage on the basis of the currently annotated proteins available in public databases. However, when the proteomics data were searched against all possible open reading frames existing in the L. donovani genome, twenty new protein-coding genes could be annotated. Additionally, 43 previously annotated proteins were extended at their N-terminal ends to accommodate peptides detected in the proteomics data. Also, different post-translational modifications (phosphorylation, acetylation, methylation, among others) were found to occur in a large number of Leishmania proteins. Finally, a detailed comparative analysis of the L. donovani and Leishmania major experimental proteomes served to illustrate how inaccurate conclusions can be raised if proteomes are compared solely on the basis of the listed proteins identified in each proteome. Finally, we have created data entries (based on freely available repositories) to provide and maintain updated gene/protein models. Raw data are available via ProteomeXchange with the identifier PXD051920.


Subject(s)
Genome, Protozoan , Leishmania donovani , Proteogenomics , Protozoan Proteins , Leishmania donovani/genetics , Leishmania donovani/metabolism , Proteogenomics/methods , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Protein Processing, Post-Translational/genetics , Proteomics/methods , Proteome/genetics , Molecular Sequence Annotation
2.
Int J Biol Macromol ; 261(Pt 2): 129612, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38272426

ABSTRACT

The industrial use of TEMPO-mediated oxidation (TMO) reaction to produce highly fibrillated cellulose nanofibrils has been hindered by high catalyst costs, long reaction times and high reaction volumes. The hypothesis that cellulose concentration during TMO process is key to increase the process of efficiency has been confirmed. The novelty of this research is the proof-of-concept for a significant enhancement of the TMO reaction by kneading the cellulose to work in concentrations above 120 g/L. Results show that the increase of the cellulose concentration in the TMO reaction, from the traditional 10 g/L to 120 g/L, increase not only the production for the same reaction volume (1200 %) but also the pulp recovery (up to 94 %). Moreover, the oxidation time can be reduced from 42 min to only 4 min while properties of both the oxidized pulps and the final nanocellulose are similar. On the other hand, the use of buffers in the TMO reaction allows us to keep the pH constant without using NaOH, and to improve the selectivity of the carboxyl groups production. The proposed process also minimizes the final environmental impact.


Subject(s)
Cellulose , Nanofibers , Cellulose/chemistry , Nanofibers/chemistry , Cyclic N-Oxides/chemistry , Oxidation-Reduction
3.
Data Brief ; 52: 109944, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38293579

ABSTRACT

This article describes data related to the research paper "Simplification of gel point characterization of cellulose nano and microfiber suspensions" [1]. The characterization of fibrillated celluloses that include cellulose nano and microfibrils (CMNFs) is a challenge for their production on an industrial scale, requiring easy techniques that control their quality and reproducibility. Gel point is a convenient parameter commonly used to estimate the aspect ratio (AR) of CMNFs. However, this estimation requires many sedimentation experiments, which are tedious and time consuming. The dataset includes all information related to the traditional experiments and to the simplified experiments for estimating gel point and AR based on only one sedimentation experiment. The full data set is useful to select the initial concentration to carry out the experimentation. This dataset also includes the information for the validation of the proposed simplified methodology and shows that the errors are lower than 7% for the gel point calculation and of 3% for the AR estimation. A larger databased of nanocellulose suspensions can be built with the reuse of this data to allow the estimation of nanocellulose properties in a future.

4.
J Interferon Cytokine Res ; 44(1): 26-36, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37962860

ABSTRACT

Although the modulation of immunity by exercise has been a long-studied paradigm, the molecular pathways connecting the two are still not fully understood. Regular moderate aerobic exercise is associated with improved health and directly impacts the immune system by changing the proportion of cell subpopulations, their function, and interleukin production. The endocannabinoid system has gained importance as an immune modulator, affected by moderate aerobic promoting the production of endocannabinoids, which are ligands of the cannabinoid receptors (CBRs) expressed on the surface of all immune cells. Our group previously reported a reduction of lymphocytic populations in the spleen of chronically exercised rats, accompanied by an increase in CBR expression. Given the complex and compartmentalized nature of the immune system, we decided to study the effects of chronic exercise on the proportion of peripheral blood mononuclear cells, serum interleukins, and the expression of CBRs on these cells. Overall, our results indicate that chronic exercise decreases the proportion of T helper and Tγδ cells but increases the expression of cannabinoids (CBR1) on T helper and natural killer cells, and the production of interleukins, including IL-1ß, interferon-gamma, tumor necrosis factor-alpha, IL-10, and IL-4, suggesting higher reactivity and efficiency from the immune system conferred by exercise.


Subject(s)
Cytokines , Leukocytes, Mononuclear , Rats , Animals , Cytokines/metabolism , Interleukins/metabolism , Killer Cells, Natural , Tumor Necrosis Factor-alpha/metabolism
5.
Nanomaterials (Basel) ; 13(18)2023 Sep 11.
Article in English | MEDLINE | ID: mdl-37764564

ABSTRACT

The cost-effective implementation of nanofibrillated cellulose (CNF) at industrial scale requires optimizing the quality of the nanofibers according to their final application. Therefore, a portfolio of CNFs with different qualities is necessary, as well as further knowledge about how to obtain each of the main qualities. This paper presents the influence of various production techniques on the morphological characteristics and properties of CNFs produced from a mixture of recycled fibers. Five different pretreatments have been investigated: a mechanical pretreatment (PFI refining), two enzymatic hydrolysis strategies, and TEMPO-mediated oxidation under two different NaClO concentrations. For each pretreatment, five high-pressure homogenization (HPH) conditions have been considered. Our results show that the pretreatment determines the yield and the potential of HPH to enhance fibrillation and, therefore, the final CNF properties. These results enable one to select the most effective production method with the highest yield of produced CNFs from recovered paper for the desired CNF quality in diverse applications.

6.
Front Public Health ; 11: 1226888, 2023.
Article in English | MEDLINE | ID: mdl-37663841

ABSTRACT

Background: We are currently undergoing a profound process of digital transformation that has favoured the development and use of apps in multiple facets of people's daily lives. In the fitness industry, this situation has facilitated the control of exercise and the maintenance of healthier lifestyles. However, it is not known how the perceived quality and importance of fitness apps vary for users based on gender and age, which is the objective of this study conducted among users of fitness centres. Methods: By means of a convenience sample, 321 users from different centres of the boutique fitness chain Sano Centre (238 females and 83 males) took part in the study. They answered the 16 items of the MARS scale, distributed in four dimensions, in terms of importance and perceived quality. The existence of significant differences was analysed using non-parametrical statistics such as the U-Mann-Whitney (gender) and the H-Kruskal-Wallis (age). In addition, a cluster analysis, combining hierarchical and non-hierarchical methods, was analysed considering as a dependent variable the level of recommendation of fitness apps. Results: Considering gender, in importance-performance analysis (IPA), credibility was the most important attribute for females and quality of information for males. In the case of age, credibility was the most important attribute in all the ranges. The cluster analysis established two groups (high and low recommendations of the fitness app). In importance, the first group scored better on all factors except entertainment and interest. In valuation, the scores were lower than on importance, especially in the low recommendation group. Conclusion: Regarding usage behaviour, credibility is the factor to which users attach the highest importance and rating, regardless of gender and age. The main demand focuses on improving the gestural design and visual appeal, which will facilitate a better user experience.


Subject(s)
Exercise , Healthy Lifestyle , Female , Male , Humans , Cluster Analysis , Industry , Research Design
7.
Genes (Basel) ; 14(8)2023 08 17.
Article in English | MEDLINE | ID: mdl-37628688

ABSTRACT

Advances in next-generation sequencing methodologies have facilitated the assembly of an ever-increasing number of genomes. Gene annotations are typically conducted via specialized software, but the most accurate results require additional manual curation that incorporates insights derived from functional and bioinformatic analyses (e.g., transcriptomics, proteomics, and phylogenetics). In this study, we improved the annotation of the Leishmania donovani (strain HU3) genome using publicly available data from the deep sequencing of ribosome-protected mRNA fragments (Ribo-Seq). As a result of this analysis, we uncovered 70 previously non-annotated protein-coding genes and improved the annotation of around 600 genes. Additionally, we present evidence for small upstream open reading frames (uORFs) in a significant number of transcripts, indicating their potential role in the translational regulation of gene expression. The bioinformatics pipelines developed for these analyses can be used to improve the genome annotations of other organisms for which Ribo-Seq data are available. The improvements provided by these studies will bring us closer to the ultimate goal of a complete and accurately annotated L. donovani genome and will enhance future transcriptomics, proteomics, and genetics studies.


Subject(s)
Leishmania donovani , Ribosome Profiling , Leishmania donovani/genetics , Gene Expression Profiling , RNA, Messenger/genetics , Ribosomes/genetics
8.
Materials (Basel) ; 16(16)2023 Aug 10.
Article in English | MEDLINE | ID: mdl-37629862

ABSTRACT

The present work reports the synthesis and the physicochemical characterization of biochar from the organic wastes of nopal (Opuntia Leucotricha), coffee grounds (Coffea arabica) and Ataulfo mango seeds (Mangifera indica) as alternative electrocatalyst supports to Vulcan XC-72 carbon black. The biochars were prepared using pyrolysis from organic wastes collected at three temperatures, 600, 750 and 900 °C, under two atmospheres, N2 and H2. The synthesized biochars were characterized using Raman spectroscopy and scanning electron microscopy (SEM) to obtain insights into their chemical structure and morphological nature, respectively, as a function of temperature and pyrolysis atmosphere. A N2 adsorption/desorption technique, two-point conductivity measurements and cyclic voltammetry (CV) were conducted to evaluate the specific surface area (SSA), electrical conductivity and double-layer capacitance, respectively, of all the biochars to estimate their physical properties as a possible alternative carbon support. The results indicated that the mango biochar demonstrated the highest properties among all the biochars, such as an electrical conductivity of 8.3 S/cm-1 at 900 °C in N2, a specific surface area of 829 m2/g at 600 °C in H2 and a capacitance of ~300 mF/g at 900 °C in N2. The nopal and coffee biochars exhibited excellent specific surface areas, up to 767 m2/g at 600 °C in N2 and 699 m2/g at 750 °C in H2, respectively; nonetheless, their electrical conductivity and capacitance were limited. Therefore, the mango biochar at 900 °C in N2 was considered a suitable alternative carbon material for electrocatalyst support. Additionally, it was possible to determine that the electrical conductivity and capacitance increased as a function of the pyrolysis temperature, while the specific surface area decreased for some biochars as the pyrolysis temperature increased. Overall, it is possible to conclude that heat treatment at a high temperature of 900 °C enhanced the biochar properties toward electrocatalyst support applications.

9.
Carbohydr Polym ; 319: 121168, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37567710

ABSTRACT

The potential of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)-mediated oxidation (TMO) to produce cellulose nanofibrils (CNFs) is hindered using costly and environmentally harmful catalysts, limiting its large-scale implementation. To promote sustainability, the TMO medium should be reused but there is a lack of knowledge on this process. The novelty of this research is the identification of the key parameters that affect the recirculation of the TMO medium, and their impact on the quality of the oxidized pulps and CNF products. Contrary to previous hypothesis, results show that the accumulation of salts is not a key parameter; instead, the pulp consistency during oxidation plays a vital role since concentrations higher than 10 g/L led to better CNF quality. Thus, reusing 75 % of the reaction medium, when high pulp consistency is used, does not alter the CNF properties. By reusing the reaction medium up to six times, the catalyst dose is dramatically reduced by >90 % for TEMPO and 80 % for NaBr, compared to the conventional process (0.1 mmol of TEMPO/g and 1 mmol of NaBr/g without medium reuse). Additionally, the high consistency oxidation enables a reduction of >80 % in the reaction time and effluent, and thus a threefold increase in CNF production.

10.
Int J Biol Macromol ; 248: 125886, 2023 Sep 01.
Article in English | MEDLINE | ID: mdl-37481180

ABSTRACT

The use of cellulose micro/nanofibrils (CMNFs) as reinforcement paper additive at industrial scale is delayed due to inconsistent results, suggesting a lack of proper consideration of some key parameters. The high influence of fibrillated nanocellulose dispersion has been recently identified as a key parameter for paper bulk reinforcement but it has not been studied for surface coating applications yet. This paper studies the effect of CMNF dispersion degree prior to their addition and during mixing with starch on the reinforcement of paper by coating. Results show that this effect depends on the type of CMNFs since it is related to the surface interactions. For a given formulation, a correlation is observed between the CMNF dispersion and the CMNF/starch mixing agitation with the rheology of the coating formulation which highly affects the paper properties. The optimal dispersion degree is different for each nanocellulose, but the best mechanical properties were always achieved at the lowest viscosity of the coating formulation. In general, the initial state of the nanocellulose 3D network, influences the mixing and smooth application of the coating and affects the reinforcement effect. Therefore, the CMNF industrial implementation in coating formulations will be facilitated by the on-line control of formulations prior to their surface application.


Subject(s)
Cellulose , Industry , Rheology , Starch , Viscosity
11.
Nanomaterials (Basel) ; 13(13)2023 Jun 25.
Article in English | MEDLINE | ID: mdl-37446447

ABSTRACT

To extend the application of cost-effective high-yield pulps in packaging, strength and barrier properties are improved by advanced-strength additives or by hot-pressing. The aim of this study is to assess the synergic effects between the two approaches by using nanocellulose as a bulk additive, and by hot-pressing technology. Due to the synergic effect, dry strength increases by 118% while individual improvements are 31% by nanocellulose and 92% by hot-pressing. This effect is higher for mechanical fibrillated cellulose. After hot-pressing, all papers retain more than 22% of their dry strength. Hot-pressing greatly increases the paper's ability to withstand compressive forces applied in short periods of time by 84%, with a further 30% increase due to the synergic effect of the fibrillated nanocellulose. Hot-pressing and the fibrillated cellulose greatly decrease air permeability (80% and 68%, respectively) for refining pretreated samples, due to the increased fiber flexibility, which increase up to 90% using the combined effect. The tear index increases with the addition of nanocellulose, but this effect is lost after hot-pressing. In general, fibrillation degree has a small effect which means that low- cost nanocellulose could be used in hot-pressed papers, providing products with a good strength and barrier capacity.

12.
Nanomaterials (Basel) ; 13(13)2023 Jun 29.
Article in English | MEDLINE | ID: mdl-37446493

ABSTRACT

In this work, the extraction of vanadium (V) ions from an alkaline solution using a commercial quaternary ammonium salt and the production of metal vanadates through precipitation stripping were carried out. The crystallization of copper vanadates from the extracts was performed using a solution containing a copper(II) source in concentrated chloride media as a stripping agent. In an attempt to control growth, a stabilizing polymer (polyvinylpyrrolidone, PVP) was added to the stripping solution. The structural characteristics of the crystallized products, mainly copper pyrovanadate (volborthite, Cu3V2O7(OH)2·(H2O)2) nanoflakes and nanoflowers and the experimental parameter influencing the efficiency of the stripping process were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable three-dimensional structures providing abundant active zones for energy and catalytic applications.

13.
Nanomaterials (Basel) ; 12(24)2022 Dec 19.
Article in English | MEDLINE | ID: mdl-36558352

ABSTRACT

Vegetable supply in the world is more than double than vegetable intake, which supposes a significant waste of vegetables, in addition to the agricultural residues produced. As sensitive food products, the reasons for this waste vary from the use of only a part of the vegetable due to its different properties to the product appearance and market image. An alternative high-added-value application for these wastes rich in cellulose could be the reduction in size to produce lignocellulose micro- and nanofibrils (LCMNF). In this sense, a direct treatment of greengrocery waste (leek, lettuce, and artichoke) to produce LCMNFs without the extraction of cellulose has been studied, obtaining highly concentrated suspensions, without using chemicals. After drying the wastes, these suspensions were produced by milling and blending at high shear followed by several passes in the high-pressure homogenizer (up to six passes). The presence of more extractives and shorter fiber lengths allowed the obtention of 5-5.5% leek LCMNF suspensions and 3.5-4% lettuce LCMNF suspensions, whereas for artichoke, only suspensions of under 1% were obtained. The main novelty of the work was the obtention of a high concentration of micro- and nanofiber suspension from the total waste without any pretreatment. These high concentrations are not obtained from other raw materials (wood or annual plants) due to the clogging of the homogenizer, requiring the dilution of the sample up to 1% or the use of chemical pretreatments.

14.
Polymers (Basel) ; 14(16)2022 Aug 22.
Article in English | MEDLINE | ID: mdl-36015682

ABSTRACT

Cellulose nanofibers (CNF) are sustainable nanomaterials, obtained by the mechanical disintegration of cellulose, whose properties make them an interesting adsorbent material due to their high specific area and active groups. CNF are easily functionalized to optimize the performance for different uses. The hypothesis of this work is that hydrophobization can be used to improve their ability as adsorbents. Therefore, hydrophobic CNF was applied to adsorb hexavalent chromium from wastewater. CNF was synthetized by TEMPO-mediated oxidation, followed by mechanical disintegration. Hydrophobization was performed using methyl trimetoxysilane (MTMS) as a hydrophobic coating agent. The adsorption treatment of hexavalent chromium with hydrophobic CNF was optimized by studying the influence of contact time, MTMS dosage (0-3 mmol·g-1 CNF), initial pH of the wastewater (3-9), initial chromium concentration (0.10-50 mg·L-1), and adsorbent dosage (250-1000 mg CNF·L-1). Furthermore, the corresponding adsorption mechanism was identified. Complete adsorption of hexavalent chromium was achieved with CNF hydrophobized with 1.5 mmol MTMS·g-1 CNF with the faster adsorption kinetic, which proved the initial hypothesis that hydrophobic CNF improves the adsorption capacity of hydrophilic CNF. The optimal adsorption conditions were pH 3 and the adsorbent dosage was over 500 mg·L-1. The maximum removal was found for the initial concentrations of hexavalent chromium below 1 mg·L-1 and a maximum adsorption capacity of 70.38 mg·g-1 was achieved. The kinetic study revealed that pseudo-second order kinetics was the best fitting model at a low concentration while the intraparticle diffusion model fit better for higher concentrations, describing a multi-step mechanism of hexavalent chromium onto the adsorbent surface. The Freundlich isotherm was the best adjustment model.

15.
Sensors (Basel) ; 22(14)2022 Jul 07.
Article in English | MEDLINE | ID: mdl-35890786

ABSTRACT

The digital transformation of the defence sector is not exempt from innovative requirements and challenges, with the lack of availability of reliable, unbiased and consistent data for training automatisms (machine learning algorithms, decision-making, what-if recreation of operational conditions, support the human understanding of the hybrid operational picture, personnel training/education, etc.) being one of the most relevant gaps. In the context of cyber defence, the state-of-the-art provides a plethora of data network collections that tend to lack presenting the information of all communication layers (physical to application). They are synthetically generated in scenarios far from the singularities of cyber defence operations. None of these data network collections took into consideration usage profiles and specific environments directly related to acquiring a cyber situational awareness, typically missing the relationship between incidents registered at the hardware/software level and their impact on the military mission assets and objectives, which consequently bypasses the entire chain of dependencies between strategic, operational, tactical and technical domains. In order to contribute to the mitigation of these gaps, this paper introduces CYSAS-S3, a novel dataset designed and created as a result of a joint research action that explores the principal needs for datasets by cyber defence centres, resulting in the generation of a collection of samples that correlate the impact of selected Advanced Persistent Threats (APT) with each phase of their cyber kill chain, regarding mission-level operations and goals.


Subject(s)
Awareness , Software , Algorithms , Communication , Humans , Machine Learning
16.
Nanomaterials (Basel) ; 12(9)2022 May 09.
Article in English | MEDLINE | ID: mdl-35564321

ABSTRACT

The current trends in micro-/nanofibers offer a new and unmissable chance for the recovery of cellulose from non-woody crops. This work assesses a technically feasible approach for the production of micro- and nanofibrillated cellulose (MNFC) from jute, sisal and hemp, involving refining and enzymatic hydrolysis as pretreatments. Regarding the latter, only slight enhancements of nanofibrillation, transparency and specific surface area were recorded when increasing the dose of endoglucanases from 80 to 240 mg/kg. This supports the idea that highly ordered cellulose structures near the fiber wall are resistant to hydrolysis and hinder the diffusion of glucanases. Mechanical MNFC displayed the highest aspect ratio, up to 228 for hemp. Increasing the number of homogenization cycles increased the apparent viscosity in most cases, up to 0.14 Pa·s at 100 s-1 (1 wt.% consistency). A shear-thinning behavior, more marked for MNFC from jute and sisal, was evidenced in all cases. We conclude that, since both the raw material and the pretreatment play a major role, the unique characteristics of non-woody MNFC, either mechanical or enzymatically pretreated (low dose), make it worth considering for large-scale processes.

17.
Nanomaterials (Basel) ; 12(5)2022 Feb 26.
Article in English | MEDLINE | ID: mdl-35269278

ABSTRACT

The dispersion degree of cellulose micro and nanofibrils (CMFs/CNFs) in water suspensions is key to understand and optimize their effectiveness in several applications. In this study, we proposed a method, based on gel point (Øg), to calculate both aspect ratio and dispersion degree. This methodology was validated through the morphological characterization of CMFs/CNFs by Transmission Electronic Microscopy. The influence of dispersion degree on the reinforcement of recycled cardboard has also been evaluated by stirring CMF/CNF suspensions at different speeds. Results show that as stirring speed increases, Øg decreased to a minimum value, in which the aspect ratio is maximum. Then, Øg increased again. Suspensions with lower Øg, in the intermediate region of agitation present very good dispersion behavior with an open and spongy network structure, in which nanofibril clusters are totally dispersed. Higher stirring speeds shorten the nanofibrils and the networks collapse. Results show that the dispersion of the nanocellulose at the minimum Øg before their addition to the pulp, produces higher mechanical properties, even higher than when CNFs and pulp are agitated together. This method allows for the determination of the CMF/CNF dispersion, to maximize their behavior as strength agents. This knowledge would be crucial to understand why some industrial trials did not give satisfactory results.

18.
Int J Biol Macromol ; 205: 220-230, 2022 Apr 30.
Article in English | MEDLINE | ID: mdl-35182566

ABSTRACT

Current knowledge on the properties of different types of cellulose nanofibers (CNFs) is fragmented. Properties variation is very extensive, depending on raw materials, effectiveness of the treatments to extract the cellulose fraction from the lignocellulosic biomass, pretreatments to facilitate cellulose fibrillation and final mechanical process to separate the microfibrils. Literature offers multiple parameters to characterize the CNFs prepared by different routes. However, there is a lack of an extensive guide to compare the CNFs. In this study, we perform a critical comparison of rheological, compositional, and morphological features of CNFs, produced from the most representative types of woody plants, hardwood and softwood, using different types and intensities of pretreatments, including enzymatic, chemical and mechanical ones, and varying the severity of mechanical treatment focusing on the relationship between macroscopic and microscopic parameters. This structured information will be exceedingly useful to select the most appropriate CNF for a certain application based on the most relevant parameters in each case.


Subject(s)
Nanofibers , Biomass , Cellulose/chemistry , Mechanical Phenomena , Nanofibers/chemistry , Rheology
19.
Int J Biol Macromol ; 187: 789-799, 2021 Sep 30.
Article in English | MEDLINE | ID: mdl-34352317

ABSTRACT

The transition of nanocellulose production from laboratory to industrial scale requires robust monitoring systems that keeps a quality control along the production chain. The present work aims at providing a deeper insight on the main factors affecting the rheological behavior of (ligno)cellulose micro/nanofibers (LCMNFs) and cellulose micro/nanofibers (CMNFs) and how they could correlate with their characteristics. To this end, 20 types of LCMNFs and CMNFs were produced combining mechanical refining and high-pressure homogenization from different raw materials. Aspect ratio and bending capacity of the fibrils played a key role on increasing the viscosity of the suspensions by instigating the formation of entangled structures. Surface charge, reflected by the cationic demand, played opposing effects on the viscosity by reducing the fibrils' contact due to repulsive forces. The suspensions also showed increasing shear-thinning behavior with fibrillation degree, which was attributed to increased surface charge and higher water retention capacity, enabling the fibrils to slide past each other more easily when subjected to flow conditions. The present work elucidates the existing relationships between LCMNF/CMNF properties and their rheological behavior, considering fibrillation intensity and the initial raw material characteristics, in view of the potential of rheological measurements as an industrial scalable characterization technology.


Subject(s)
Cellulose/chemistry , Lignans/chemistry , Nanofibers , Picea/chemistry , Pinus/chemistry , Cellulose/isolation & purification , Lignans/isolation & purification , Rheology , Species Specificity , Surface Properties , Viscosity , Water/chemistry
20.
Nanomaterials (Basel) ; 11(8)2021 Aug 16.
Article in English | MEDLINE | ID: mdl-34443907

ABSTRACT

The present paper proposes a novel approach for the morphological characterization of cellulose nano and microfibers suspensions (CMF/CNFs) based on the analysis of eroded CMF/CNF microscopy images. This approach offers a detailed morphological characterization and quantification of the micro and nanofibers networks present in the product, which allows the mode of fibrillation associated to the different CMF/CNF extraction conditions to be discerned. This information is needed to control CMF/CNF quality during industrial production. Five cellulose raw materials, from wood and non-wood sources, were subjected to mechanical, enzymatic, and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-mediated oxidative pre-treatments followed by different homogenization sequences to obtain products of different morphologies. Skeleton analysis of microscopy images provided in-depth morphological information of CMF/CNFs that, complemented with aspect ratio information, estimated from gel point data, allowed the quantification of: (i) fibers peeling after mechanical pretreatment; (ii) fibers shortening induced by enzymes, and (iii) CMF/CNF entanglement from TEMPO-mediated oxidation. Being mostly based on optical microscopy and image analysis, the present method is easy to implement at industrial scale as a tool to monitor and control CMF/CNF quality and homogeneity.

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