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  1. Article ; Online: Estimating RNA dynamics using one time point for one sample in a single-pulse metabolic labeling experiment

    Micha Hersch / Adriano Biasini / Ana C. Marques / Sven Bergmann

    BMC Bioinformatics, Vol 23, Iss 1, Pp 1-

    2022  Volume 17

    Abstract: Abstract Background Over the past decade, experimental procedures such as metabolic labeling for determining RNA turnover rates at the transcriptome-wide scale have been widely adopted and are now turning to single cell measurements. Several ... ...

    Abstract Abstract Background Over the past decade, experimental procedures such as metabolic labeling for determining RNA turnover rates at the transcriptome-wide scale have been widely adopted and are now turning to single cell measurements. Several computational methods to estimate RNA synthesis, processing and degradation rates from such experiments have been suggested, but they all require several RNA sequencing samples. Here we present a method that can estimate those three rates from a single sample. Methods Our method relies on the analytical solution to the Zeisel model of RNA dynamics. It was validated on metabolic labeling experiments performed on mouse embryonic stem cells. Resulting degradation rates were compared both to previously published rates on the same system and to a state-of-the-art method applied to the same data. Results Our method is computationally efficient and outputs rates that correlate well with previously published data sets. Using it on a single sample, we were able to reproduce the observation that dynamic biological processes tend to involve genes with higher metabolic rates, while stable processes involve genes with lower rates. This supports the hypothesis that cells control not only the mRNA steady-state abundance, but also its responsiveness, i.e., how fast steady state is reached. Moreover, degradation rates obtained with our method compare favourably with the other tested method. Conclusions In addition to saving experimental work and computational time, estimating rates for a single sample has several advantages. It does not require an error-prone normalization across samples and enables the use of replicates to estimate uncertainty and assess sample quality. Finally the method and theoretical results described here are general enough to be useful in other contexts such as nucleotide conversion methods and single cell metabolic labeling experiments.
    Keywords RNA metabolic labeling ; RNA dynamics ; RNA responsiveness ; Zeisel model ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2022-04-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Biodegradable Microcapsules of Poly(Butylene Adipate- co -Terephthalate) (PBAT) as Isocyanate Carriers and the Effect of the Process Parameters

    António Aguiar / António Mariquito / Diogo Gonçalves / Isabel Pinho / Ana C. Marques

    Polymers, Vol 15, Iss 665, p

    2023  Volume 665

    Abstract: Poly(butylene adipate- co -terephthalate) (PBAT), a biodegradable flexible, and tough polymer is herein used, for the first time, to encapsulate and protect isocyanate derivatives. Isocyanates are essential building blocks widely employed in the chemical ...

    Abstract Poly(butylene adipate- co -terephthalate) (PBAT), a biodegradable flexible, and tough polymer is herein used, for the first time, to encapsulate and protect isocyanate derivatives. Isocyanates are essential building blocks widely employed in the chemical industry for the production of high-performing materials. Microencapsulation of isocyanates eliminates the risks associated with their direct handling and protects them from moisture. In light of this, and having in mind eco-innovative products and sustainability, we present a straightforward process to encapsulate isophorone diisocyanate (IPDI) using this biodegradable polymer. Spherical and core-shell microcapsules (MCs) were produced by an emulsion system combined with the solvent evaporation method. The MCs present a regular surface, without holes or cracks, with a thin shell and high isocyanate loadings, up to 79 wt%. Additionally, the MCs showed very good isocyanate protection if not dispersed in organic or aqueous solutions. Effects of various process parameters were systematically studied, showing that a higher stirring speed (1000 rpm) and emulsifier amount (2.5 g), as well as a smaller PBAT amount (1.60 g), lead to smaller MCs and narrower size distribution.
    Keywords Poly(butylene adipate- co -terephthalate) ; PBAT ; biodegradable microcapsules ; isophorone diisocyanate ; IPDI ; solvent evaporation ; Organic chemistry ; QD241-441
    Subject code 660
    Language English
    Publishing date 2023-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Development of BioPolyurethane Coatings from Biomass-Derived Alkylphenol Polyols—A Green Alternative

    Tiago A. R. Silva / Ana C. Marques / Rui G. dos Santos / Rana A. Shakoor / Maryna Taryba / Maria Fátima Montemor

    Polymers, Vol 15, Iss 2561, p

    2023  Volume 2561

    Abstract: Bio-based polyols were obtained from the thermochemical liquefaction of two biomass feedstocks, pinewood and Stipa tenacissima , with conversion rates varying between 71.9 and 79.3 wt.%, and comprehensively characterized. They exhibit phenolic and ... ...

    Abstract Bio-based polyols were obtained from the thermochemical liquefaction of two biomass feedstocks, pinewood and Stipa tenacissima , with conversion rates varying between 71.9 and 79.3 wt.%, and comprehensively characterized. They exhibit phenolic and aliphatic moieties displaying hydroxyl (OH) functional groups, as confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. The biopolyols obtained were successfully employed as a green raw material to produce bio-based polyurethane (BioPU) coatings on carbon steel substrates, using, as an isocyanate source, a commercial bio-based polyisocyanate—Desmodur ® Eco N7300. The BioPU coatings were analyzed in terms of chemical structure, the extent of the reaction of the isocyanate species, thermal stability, hydrophobicity, and adhesion strength. They show moderate thermal stability at temperatures up to 100 °C, and a mild hydrophobicity, displaying contact angles between 68° and 86°. The adhesion tests reveal similar pull-off strength values (ca. 2.2 MPa) for the BioPU either prepared with pinewood and Stipa -derived biopolyols (BPUI and BPUII). Electrochemical impedance spectroscopy (EIS) measurements were carried out on the coated substrates for 60 days in 0.05 M NaCl solution. Good corrosion protection properties were achieved for the coatings, with particular emphasis on the coating prepared with the pinewood-derived polyol, which exhibited a low-frequency impedance modulus normalized for the coating thickness of 6.1 × 10 10 Ω cm at the end of the 60 days test, three times higher than for coatings prepared with Stipa -derived biopolyols. The produced BioPU formulations show great potential for application as coatings, and for further modification with bio-based fillers and corrosion inhibitors.
    Keywords thermochemical liquefaction ; biomass ; biopolyols ; biopolyurethane ; polyurethane coatings ; corrosion protection ; Organic chemistry ; QD241-441
    Subject code 620
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Influence of CO2 laser beam modelling on electronic and electrochemical properties of paper-based laser-induced graphene for disposable pH electrochemical sensors

    Tomás Pinheiro / André Rosa / Cristina Ornelas / João Coelho / Elvira Fortunato / Ana C. Marques / Rodrigo Martins

    Carbon Trends, Vol 11, Iss , Pp 100271- (2023)

    2023  

    Abstract: Laser-induced graphene (LIG) allows for the fabrication of cost-effective, flexible electrodes on a multitude of recyclable and sustainable substrates, for implementation within electrochemical biosensors. This work expands on current LIG research, by ... ...

    Abstract Laser-induced graphene (LIG) allows for the fabrication of cost-effective, flexible electrodes on a multitude of recyclable and sustainable substrates, for implementation within electrochemical biosensors. This work expands on current LIG research, by experimentally modeling the effects of several CO2 laser irradiation variables towards resulting conductive and electrochemical properties of paper-derived LIG. Instead of relying on the established paradigm of manipulating power and scan speed of the laser irradiation process for optimized outcomes, modeling of underlying laser operation principles for pulse modulation, regarding pulse repetition frequencies, pulse duration and defocus are presented as the key aspects dominating graphitization processes of materials. This approach shows that graphitization is dominated by appropriate pulse durations, dictating the time the substrate is exposed to each laser pulse, with laser fluence and irradiation defocus influencing the resulting conductive properties, with sheet resistances as low as 14 Ω sq−1. Similarly, fabrication settings controlled by these parameters have a direct influence on the properties of LIG-based electrochemical three-electrode cells, with optimized fabrication settings reaching electrochemically active surface area as high as 35 mm2 and heterogeneous electron transfer rates of 3.4 × 10−3 cm.s−1. As a proof-of-concept, the production of environmentally friendly, accessible, and biocompatible pH sensors is demonstrated, using two modification approaches, employing riboflavin and polyaniline as pH-sensitive elements.
    Keywords Laser-induced graphene ; CO2 laser ; Paper electronics ; Electrochemical sensors ; pH ; Sustainable production ; Chemistry ; QD1-999
    Subject code 620
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Development of Composites of PLA Filled with Different Amounts of Rice Husk Fibers for Fused Deposition Modeling

    Daniel F. Pereira / A.C. Branco / Ricardo Cláudio / Ana C. Marques / C. G. Figueiredo-Pina

    Journal of Natural Fibers, Vol 20, Iss

    2023  Volume 1

    Abstract: Polylactic acid (PLA) has been used as a matrix material to produce composites with natural fibers, which present several advantages, being one of them the addition of value to agricultural waste. Thus, this study aims to develop a PLA 3D filament with ... ...

    Abstract Polylactic acid (PLA) has been used as a matrix material to produce composites with natural fibers, which present several advantages, being one of them the addition of value to agricultural waste. Thus, this study aims to develop a PLA 3D filament with the incorporation of a waste agriculture product (rice husk (RH)). For that, RH fibers were prepared, and PLA was loaded up to 20% RH. The filaments were obtained by extrusion. Finally, samples were produced by fused deposition modeling (FDM). The fibers and filaments’ density and thermal stability (TGA) were determined, and their chemical structure changes due to alkali treatment were accessed by Fourier Transform Infrared Spectroscopy (FTIR). Printability tests were performed, and printed samples were characterized in terms of density, water absorption, and mechanical behavior (compression, tensile, and flexural tests). The results showed that the alkali treatment changed the chemical structure of RH fibers and TGA showed that the filaments did not degrade significantly until 250ºC. The best printability was achieved with 5% of HR content and was the one that showed the lowest mechanical properties reduction. Overall, the present work showed that RH fibers can be successfully used as a filler in PLA filaments for FDM.
    Keywords rice husk ; natural fiber-filled polymer ; additive manufacturing ; pla ; mechanical properties ; composites ; Science ; Q ; Textile bleaching ; dyeing ; printing ; etc ; TP890-933
    Subject code 660
    Language English
    Publishing date 2023-04-01T00:00:00Z
    Publisher Taylor & Francis Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Design of Experiment for Optimizing Microencapsulation by the Solvent Evaporation Technique

    Mónica V. Loureiro / António Aguiar / Rui G. dos Santos / João C. Bordado / Isabel Pinho / Ana C. Marques

    Polymers, Vol 16, Iss 1, p

    2023  Volume 111

    Abstract: We employed microemulsion combined with the solvent evaporation technique to produce biodegradable polycaprolactone (PCL) MCs, containing encapsulated isophorone diisocyanate (IPDI), to act as crosslinkers in high-performance adhesive formulations. The ... ...

    Abstract We employed microemulsion combined with the solvent evaporation technique to produce biodegradable polycaprolactone (PCL) MCs, containing encapsulated isophorone diisocyanate (IPDI), to act as crosslinkers in high-performance adhesive formulations. The MC production process was optimized by applying a design of experiment (DoE) statistical approach, aimed at decreasing the MCs’ average size. For that, three different factors were considered, namely the concentration of two emulsifiers, polyvinyl alcohol (PVA) and gum arabic (GA); and the oil-to-water phase ratio of the emulsion. The significance of each factor was evaluated, and a predictive model was developed. We were able to decrease the average MC size from 326 μm to 70 µm, maintaining a high encapsulation yield of approximately 60% of the MCs’ weight, and a very satisfactory shelf life. The MCs’ average size optimization enabled us to obtain an improved distributive and dispersive mixture of isocyanate-loaded MCs at the adhesive bond. The MCs’ suitability as crosslinkers for footwear adhesives was assessed following industry standards. Peel tests revealed peel strength values above the minimum required for casual footwear, while the creep test results indicated an effective crosslinking of the adhesive. These results confirm the ability of the MCs to release IPDI during the adhesion process and act as crosslinkers for new adhesive formulations.
    Keywords microencapsulation ; DoE ; polycaprolactone ; isocyanate ; adhesives ; Organic chemistry ; QD241-441
    Language English
    Publishing date 2023-12-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Non-Formaldehyde, Bio-Based Adhesives for Use in Wood-Based Panel Manufacturing Industry—A Review

    Diogo Gonçalves / João Moura Bordado / Ana C. Marques / Rui Galhano dos Santos

    Polymers, Vol 13, Iss 4086, p

    2021  Volume 4086

    Abstract: There is a strong need to develop and implement appropriate alternatives to replace formaldehyde-based adhesive systems, such as phenol–formaldehyde, in the industry of wood-based panels (WBPs). This is due to the toxicity and volatility of formaldehyde ... ...

    Abstract There is a strong need to develop and implement appropriate alternatives to replace formaldehyde-based adhesive systems, such as phenol–formaldehyde, in the industry of wood-based panels (WBPs). This is due to the toxicity and volatility of formaldehyde and restrictions on its use associated with some formaldehyde-based adhesives. Additionally, the current pressure to reduce the dependence on polymeric materials, including adhesives, from petrochemical-based sources has led to increased interest in bio-based adhesives, which, in some cases, already provide acceptable properties to the end-product. Among the potential raw materials for good-quality, renewable-based adhesive formulations, this paper highlights tannins, lignin, and protein sources. However, regarding renewable sources, specific features must be considered, such as their lower reactivity than certain petrochemical-based sources and, therefore, higher production costs, resource availability issues, and the need for toxicological investigations on alternative systems, to compare them to conventional systems. As a result, further research is highly encouraged to develop viable formaldehyde-free adhesive systems based on renewable sources, either at the technical or economical level. Moreover, herein, we also showcase the present market of WBPs, highlighting the obstacles that the alternative and new bio-based adhesives must overcome.
    Keywords adhesives ; non-formaldehyde ; review ; wood-based panels ; Organic chemistry ; QD241-441
    Subject code 670
    Language English
    Publishing date 2021-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Porous Silica Microspheres with Immobilized Titania Nanoparticles for In‐Flow Solar‐Driven Purification of Wastewater

    Ana C. Marques / Mário Vale / Daniel Vicente / Murielle Schreck / Elena Tervoort / Markus Niederberger

    Global Challenges, Vol 5, Iss 5, Pp n/a-n/a (2021)

    2021  

    Abstract: Abstract In this paper, inorganic silica microspheres with interconnected macroporosity are tested as a platform for designing robust and efficient photocatalytic systems for a continuous flow reactor, enabling a low cost and straightforward purification ...

    Abstract Abstract In this paper, inorganic silica microspheres with interconnected macroporosity are tested as a platform for designing robust and efficient photocatalytic systems for a continuous flow reactor, enabling a low cost and straightforward purification of wastewater through solar‐driven photocatalysis. The photocatalytically active microspheres are prepared by wet impregnation of porous silica scaffolds with Trizma‐functionalized anatase titania (TiO2) nanoparticles (NPs). NPs loading of 22 wt% is obtained in the form of a thin and well‐attached layer, covering the external surface of the microspheres as well as the internal surface of the pores. The TiO2 loading leads to an increase of the specific surface area by 26%, without impacting the typically interconnected macroporosity (≈60%) of the microspheres, which is essential for an efficient flow of the pollutant solution during the photocatalytic tests. These are carried out in a liquid medium for the decomposition of methyl orange and paracetamol. In addition to photocatalytic activity under continuous flow, the microspheres offer the advantage that they can be easily removed from the reaction medium, which is an appealing aspect for industrial applications. In this work, the typical issues of TiO2 NPs photocatalysts are circumvented, without the need for elaborate chemistries, and for low availability and expensive raw materials.
    Keywords microspheres ; photocatalysis ; porous silica ; solar light ; sol–gel ; titania nanoparticles ; Technology ; T ; Environmental sciences ; GE1-350
    Subject code 620
    Language English
    Publishing date 2021-05-01T00:00:00Z
    Publisher Wiley
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Deacetylation and Desuccinylation of the Fucose-Rich Polysaccharide Fucopol

    Sílvia Baptista / Diana Araújo / Patrícia Concórdio-Reis / Ana C. Marques / Elvira Fortunato / Vítor D. Alves / Filomena Freitas

    Molecules, Vol 27, Iss 7165, p

    Impact on Biopolymer Physical and Chemical Properties

    2022  Volume 7165

    Abstract: FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that include a shear thinning fluid behaviour, a film-forming capacity, and an emulsion forming and stabilizing capacity. In this study, the different conditions ( ... ...

    Abstract FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that include a shear thinning fluid behaviour, a film-forming capacity, and an emulsion forming and stabilizing capacity. In this study, the different conditions (concentration, temperature, and time) for alkaline treatment were investigated to deacylate FucoPol. Complete deacetylation and desuccinylation was achieved with 0.02 M NaOH, at 60 °C for 15 min, with no significant impact on the biopolymer’s sugar composition, pyruvate content, and molecular mass distribution. FucoPol depyruvylation by acid hydrolysis was attempted, but it resulted in a very low polymer recovery. The effect of the ionic strength, pH, and temperature on the deacetylated/desuccinylated polysaccharide, d-FucoPol, was evaluated, as well as its emulsion and film-forming capacity. d-FucoPol aqueous solutions maintained the shear thinning behaviour characteristic of FucoPol, but the apparent viscosity decreased significantly. Moreover, contrary to FucoPol, whose solutions were not affected by the media’s ionic strength, the d-FucoPol solutions had a significantly higher apparent viscosity for a higher ionic strength. On the other hand, the d-FucoPol solutions were not affected by the pH in the range of 3.6–11.5, while FucoPol had a decreased viscosity for acidic pH values and for a pH above 10.5. Although d-FucoPol displayed an emulsification activity for olive oil similar to that of FucoPol (98 ± 0%) for an oil-to-water ratio of 2:3, the emulsions were less viscous. The d-FucoPol films were flexible, with a higher Young′s modulus (798 ± 152 MPa), a stress at the break (22.5 ± 2.5 MPa), and an elongation at the break (9.3 ± 0.7%) than FucoPol (458 ± 32 MPa, 15.5 ± 0.3 MPa and 8.1 ± 1.0%, respectively). Given these findings, d-FucoPol arises as a promising novel biopolymer, with distinctive properties that may render it useful for utilization as a suspending or emulsifier agent, and as a barrier in coatings and packaging films.
    Keywords deacetylation ; desuccinylation ; alkaline treatment ; polysaccharide ; FucoPol ; rheology ; Organic chemistry ; QD241-441
    Subject code 660
    Language English
    Publishing date 2022-10-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Low Temperature Dissolution of Yeast Chitin-Glucan Complex and Characterization of the Regenerated Polymer

    Diana Araújo / Vítor D. Alves / Ana C. Marques / Elvira Fortunato / Maria A. M. Reis / Filomena Freitas

    Bioengineering, Vol 7, Iss 1, p

    2020  Volume 28

    Abstract: Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the ... ...

    Abstract Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris . Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63−68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although the acetylation degree decreased from 61.3% to 33.9−50.6%, indicating that chitin was converted into chitosan, yielding chitosan-glucan complex (ChGC). Consistent with this, there was a reduction of the crystallinity index and thermal degradation temperature. Given these results, this study reports a simple and green procedure to solubilize CGC and obtain aqueous ChGC solutions that can be processed as novel biomaterials.
    Keywords chitin-glucan complex (cgc) ; chitosan-glucan complex (chgc) ; naoh/urea solvent systems ; dissolution ; structural analysis ; thermal properties ; Technology ; T ; Biology (General) ; QH301-705.5
    Subject code 540
    Language English
    Publishing date 2020-03-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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