Laccase immobilization on bacterial nanocellulose membranes: antimicrobial, kinetic and stability properties

This work studied the physical immobilization of a commercial laccase on bacterial nanocellulose (BNC) aiming to identify the laccase antibacterial properties suitable for wound dressings. Physico-chemical analysis demonstrates that the BNC structure is manly formed by pure crystalline I cellulose. The pH optimum and activation energy of free laccase depends on the substrate employed corresponding to pH 6, 7, 3 and 57, 22, 48 kJ mol1 for 2,6-dimethylphenol (DMP), catechol and 2,2 -azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), respectively. The Michaelis-Menten constant (Km) value for the immobilized laccase (0.77 mM) was found to be almost double of that of the free enzyme (0.42 mM). However, the specific activities of immobilized and free laccase are similar suggesting that the cage-like structure of BNC allows entrapped laccase to maintain some flexibility and favour substrate accessibility. The results clearly show the antimicrobial effect of laccase in Gram-positive (92%) and Gram-negative (26%) bacteria and cytotoxicity acceptable for wound dressing applications.Andrea Zille (C2011-UMINHO-2C2T-01) acknowledges FCT funding from Programa Compromisso para a Ciência 2008, Portugal, FEDER funding on the Programa Operacional Factores de Competitividade - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136 and UID/CTM/00264. Jorge Padrão and João P. Silva acknowledge Portuguese Foundation for Science and Technology (FCT) grants SFRH/BD/64901/2009 and SFRH/BPD/64958/2009 respectively. The authors Jorge Padrão, JoãoP. Silva and Fernando Dourado would like to thank the FCT StrategicProject PEst-OE/EQB/LA0023/2013, also to the Project “BioHealth −Biotechnology and Bioengineering approaches to improve healthquality”, Ref. NORTE-07-0124-FEDER-000027, co-funded by thePrograma Operacional Regional do Norte (ON.2-O Novo Norte),QREN, FEDER, and finnally to RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462)

Methodological considerations in assessing interlimb coordination on poststroke gait: a scoping review of biomechanical approaches and outcomes

To identify and summarize biomechanical assessment approaches in interlimb coordination on poststroke gait. Interlimb coordination involves complex neurophysiological mechanisms that can be expressed through the biomechanical output. The deepening of this concept would have a significant contribution in gait rehabilitation in patients with an asymmetric neurological impairment as poststroke adults. Poststroke adults (>19 years old), with assessment of interlimb coordination during gait, in an open context, according to the Population, Concept, Context framework. A literature search was performed in PubMed, Web of Science™, Scopus, and gray literature in Google Scholar™, according to the PRISMA-ScR recommendations. Studies written in Portuguese or English language and published between database inception and 14 November 2021 were included. Qualitative studies, conference proceedings, letters, and editorials were excluded. The main conceptual categories were “author/year”, “study design”, “participant’s characteristics”, “walking conditions”, “instruments” and “outcomes”. The search identified 827 potentially relevant studies, with a remaining seven fulfilling the established criteria. Interlimb coordination was assessed during walking in treadmill (n = 3), overground (n = 3) and both (n = 1). The instruments used monitored electromyography (n = 2), kinetics (n = 2), and kinematics (n = 4) to assess spatiotemporal parameters (n = 4), joint kinematics (n = 2), anteroposterior ground reaction forces (n = 2), and electromyography root mean square (n = 2) outcomes. These outcomes were mostly used to analyze symmetry indices or ratios, to calculate propulsive impulse and external mechanical power produced on the CoM, as well as antagonist coactivation. Assessment of interlimb coordination during gait is important for consideration of natural auto-selected overground walking, using kinematic, kinetic, and EMG instruments. These allow for the collection of the main biomechanical outcomes that could contribute to improve better knowledge of interlimb coordination assessment in poststroke patients.info:eu-repo/semantics/publishedVersio

Young’s modulus and hardness of multiphase CaZrO3 -MgO ceramics by micro and nanoindentation

The aim of this work is to determine the values of the hardness and elastic modulus of the phases present in CaZrO3-MgO-ZrO2 composites and to analyse their contribution to the composite properties. Two materials previously developed with the same major phases (CaZrO3, MgO and c-ZrO2) present in different volume fractions and grain size have been analysed. The hardness and Young´s modulus of each phase determined by nanoindentation are independent from the specific composite and coincident with nanoindentation values for single phase bulk materials. The contribution of the individual phases to Young´s modulus of the multiphase materials is in agreement with calculations using the nanoindentation values and the Voight upper limit of the “rule of mixtures”. Scale dependence due to microcracking has been observed for microhardness values of the composites and differences between calculations and experimental values are related to this effect.This work was performed in the frame of the CYTEDnetwork HOREF(312RT0453)and was supported by the Spanish Government underprojectMAT2013-48426-C2-1-R.AbílioP.Silvaacknowledges thefinancialsupportofJECSTrustthroughmobilityContract201597 and Instituto de Cerámica y Vidrio–CSIC.info:eu-repo/semantics/publishedVersio

Evaluation of foamed bitumen efficiency in warm asphalt mixtures recycling

The recycling of pavements is nowadays a very important question to the road paving industry. With the objective of incorporating higher percentages of reclaimed asphalt (RA) materials in recycled asphalt mixtures, new techniques have been developed in the last years. The use of foamed bitumen is normally associated with the production of cold asphalt mixtures, which usually show lower quality standards. However, the objective of the work presented in this paper is to assess the use of foamed bitumen as the binder of warm asphalt mixtures incorporating 30% RA, which have quality standards similar to those of conventional mixtures. Thus, five mixtures have been produced with 30% RA, one of them with a conventional bitumen (control mix) and the others with foamed bitumen at different production temperatures. The mixtures were tested for compactability and water sensitivity and the results show a possible reduction of 25 ºC in the production temperatures, while the water sensitivity test results were kept close to 90 %.Funded by ERDF funds through the Operational Competitiveness Program – COMPETE in the scope of Project “Energy Efficiency and Environmental Design of Bituminous Mixtures and Reducing Emissions of Greenhouse Gases” (SI Innovation Project 7603). Thanks are also due to the Foundation for Science and Technology (FCT) for funding allocated through the PhD grant SFRH/BD/85448/201

Identification of hazardous nanoparticles present in the Caribbean Sea for the allocation of future preservation projects

The deposition of remaining nanoparticles in the Caribbean Sea generates the formation of potentially dangerous elements, which influence at the imbalance of ecosystems. The detection of nanoparticles is not simple and the use of conventional methods is difficult application, which is why we highlight the immediacy and importance of this research for the areas of marine biology, urbanism, engineering and geosciences, applied in the Caribbean Sea. The general objective of this study is to evaluate the use of advanced methods for the determination of toxic nanoparticles, which can directly affect the development of marine organisms in the aquatic ecosystem in waters of the Caribbean Sea, favoring the construction of future international public policies with the elaboration of projects capable of mitigating these levels of contamination. The morphology and structure of nanoparticles were analyzed by emission scanning electron microscope with a high-resolution electron microscope. The nanoparticles smaller than 97 nm were identified in different proportions. The morphological analyses indicated nanoparticles' presence in the form of nanotubes, nanospheres, and nanofibers, which were shown in an agglomerated form. The presence of potentially hazardous elements, such as As, Cd, Pb, Mg, Ni and V were verified. In addition, the presence of asbestos in the form of minerals was confirmed, and that of titanium dioxide was found in large quantities. The results provide new data and emphasize the possible consequences to the in the Caribbean Sea, with the identification of dangerous elements (As, Cb, Pb, Hg, Ni and V), harmful to the marine ecosystem. Therefore, there is a need for strict control to reduce contamination of the Caribbean Sea and avoid risks to the ecosystem and public health, through suggestions of international public policies, through constant monitoring and the application of environmental recovery projects in this marine estuary

Preservation of probiotic strains isolated from kefir by spray drying

Aims: This work aims to investigate the survival of Lactobacillus kefir CIDCA 8348, Lactobacillus plantarum CIDCA 83114 and Saccharomyces lipolytica CIDCA 812, all isolated from kefir, during spray drying and subsequent storage. Methods and Results: Micro-organisms were grown in De Man, Rogosa, Sharpe (MRS) or yeast medium (YM) medium and harvested in the stationary phase of growth. The thermotolerance in skim milk (D and Z values), the survival of spray drying at different outlet air temperatures and subsequent storage in different conditions during 150 days were studied. The resistance to the heat treatments was higher in Lact. plantarum compared to Lact. kefir and S. lipolytica. The three micro-organisms studied varied considerably in their ability to survive to spray drying processes. Lactobacillus plantarum showed the highest survival rate for all the tested outlet air temperatures and also to the further storage in the dried state. The survival rates of Lact. kefir and S. lipolytica through drying and subsequent storage in the dried state decreased when the drying outlet air temperatures increased. Conclusions: Spray drying is a suitable method to preserve micro-organisms isolated from kefir grains. A high proportion of cells were still viable after 80 days of storage at refrigerated temperatures Significance and Impact of Study: It is the first report about spray-dried probiotic strains isolated from kefir grain and contributes to the knowledge about these micro-organisms for their future application in novel dehydrated products.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Solid-liquid phase behavior of eutectic solvents containing sugar alcohols

Mixtures of carbohydrates are often reported in the literature as deep eutectic solvents yet, in most cases, their solid–liquid phase diagrams are poorly characterized and no evidence is available to validate this classification. In this work, the phase diagrams of the binary systems composed of the sugar alcohols mannitol or maltitol and meso-erythritol, xylitol, or sorbitol, were experimentally determined. The results obtained reveal that these systems have a thermodynamic ideal behavior, questioning their classification as deep eutectic solvents and showing that intermolecular hydrogen bonding between the components of a mixture is not a sufficient condition to prepare deep eutectic solvents. The phase diagrams of the systems composed of mannitol or maltitol and cholinium chloride were also measured in this work. In sharp contrast to the mixtures composed solely by sugar alcohols, and unlike numerous other choline-based eutectic systems reported in the literature, these systems revealed significant deviations to thermodynamic ideality, leading to significant melting temperature depressions. The Cl-OH interaction between cholinium chloride and the sugar alcohols is identified as the main reason for these deviations to ideality, paving the way for the rational choice of hydrogen bond acceptors to prepare deep eutectic solvents.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, and CIMO-Mountain Research Center, UIDB/00690/2020, both financed by national funds through the Portuguese Foundation for Science and Technology(FCT)/MCTES. L.P.S. acknowledges FCT for her PhD grant (SFRH/BD/135976/2018).info:eu-repo/semantics/publishedVersio

Preservation of probiotic strains isolated from kefir by spray drying

Aims: This work aims to investigate the survival of Lactobacillus kefir CIDCA 8348, Lactobacillus plantarum CIDCA 83114 and Saccharomyces lipolytica CIDCA 812, all isolated from kefir, during spray drying and subsequent storage. Methods and Results: Micro-organisms were grown in De Man, Rogosa, Sharpe (MRS) or yeast medium (YM) medium and harvested in the stationary phase of growth. The thermotolerance in skim milk (D and Z values), the survival of spray drying at different outlet air temperatures and subsequent storage in different conditions during 150 days were studied. The resistance to the heat treatments was higher in Lact. plantarum compared to Lact. kefir and S. lipolytica. The three micro-organisms studied varied considerably in their ability to survive to spray drying processes. Lactobacillus plantarum showed the highest survival rate for all the tested outlet air temperatures and also to the further storage in the dried state. The survival rates of Lact. kefir and S. lipolytica through drying and subsequent storage in the dried state decreased when the drying outlet air temperatures increased. Conclusions: Spray drying is a suitable method to preserve micro-organisms isolated from kefir grains. A high proportion of cells were still viable after 80 days of storage at refrigerated temperatures Significance and Impact of Study: It is the first report about spray-dried probiotic strains isolated from kefir grain and contributes to the knowledge about these micro-organisms for their future application in novel dehydrated products.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Tetraalkylammonium Chlorides as Melting Point Depressants of Ionic Liquids

With the (re)advent of eutectic mixtures within the field of deep eutectic solvents, special attention has been given to the measurement of solid–liquid equilibrium (SLE) phase diagrams, supported by the relevant information they can provide on the molecular interactions and melting temperature depression of any given system. As such, this work investigates the SLE phase diagrams of mixtures between ionic liquids and tetraalkylammonium chlorides (methyl, ethyl, and propyl), with the goal of decreasing the melting temperature of ionic liquids and ammonium salts, thus, expanding their application scope. Results show that tetraalkylammonium salts exhibit negative deviations from thermodynamic ideality when mixed with ionic liquids, which are increased by increasing their alkyl chain length and are interpreted in terms of anion exchange mechanisms. In turn, this nonideality contributes greatly to depression of the melting point of the ionic liquids examined. Overall, this work demonstrates that the correct combination of tetraalkylammonium/ILs anions and cations can lead to significant melting point depressions in both species, thus creating new ionic liquid mixtures using an approach akin to that used to form deep eutectic solvents.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020, and CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2021), financed by national funds through the FCT/MEC (PIDDAC). L.P.S. acknowledges FCT for her Ph.D. Grant (SFRH/BD/135976/2018).info:eu-repo/semantics/publishedVersio

Eutectic mixtures based on polyalcohols as sustainable solvents: screening and characterization

Despite some promising potential applications of eutectic systems containing choline chloride ([Ch]Cl) and a polyalcohol, a detailed investigation of the thermodynamic behavior of these systems is still missing. In this work, the solid-liquid equilibria phase diagrams of binary systems containing [Ch]Cl and one from six different polyalcohols (ethylene glycol (EG), 1,3-propanediol, glycerol (Gly), meso-erythritol, xylitol, and sorbitol) were measured in the full composition. Except for the mixtures with Gly or EG, a quasi-ideal behavior in the [Ch]Cl solubility curve is observed. In the polyalcohol solubility curve, the mixtures present small negative deviations from ideality, except for [Ch]Cl + EG, which is slightly positive. The solid-liquid phase diagrams show a large liquid composition window, and not a fixed stoichiometry for the eutectic points, where the mixtures can be used as solvents close to, or below, room temperature. Aiming at their application, viscosities and densities were measured at the eutectic point in the temperature range from 278.15 to 373.15 K. All systems present densities and viscosities higher than water, which is directly related to the strong interactions between the components. Solvatochromic parameters were measured to characterize the solvents, and they show that solvent tunability can be achieved by varying the polyalcohol mole fraction.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, and CIMO-Mountain Research Center, UIDB/00690/2020, both financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project Nº 022161 (cofinanced by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). L.P.S. acknowledges FCT for her PhD grant (SFRH/BD/135976/2018).info:eu-repo/semantics/publishedVersio