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BACKGROUND: Prolonged fatigue effects may be a concern after futsal matches mainly because of the actions performed by futsal players (e.g., sprinting, jumping) that usually involve the stretch-shortening cycle (SSC). However, there no studies analyzed the prolonged effects of futsal-specific fatigue and how futsal players can recover from performance tasks. OBJECTIVE: To analyze the acute and prolonged effects of a protocol that simulates specific physical demands of futsal on countermovement-jump, sprint performance, muscle strength and muscle soreness. METHODS: Fifteen amateur futsal male athletes (18.3 ± 3.8 years) performed a futsal intermittent running protocol (FIRP) and were assessed for (moment production, sprint and jumping performance and muscle soreness) at pre, during half-time, immediately after, post 24 and 48 hours after the FIRP. Analysis of variance (repeated measures) was used to compare variable means over time. RESULTS: The main results indicated a decrement in the CMJ height (p = 0.03) and an increase of 10 m and 20 m sprint times (p = 0.01– p < 0.01, respectively) during half-time and the post FIRP. There was a decrement in eccentric peak moment of the knee extensors (p = 0.02) and flexors (p < 0.01) until 48h post protocol and a decrement in concentric peak moment of the flexors (p < 0.01) post protocol. Athletes reported muscle soreness in the hamstrings (p = 0.03) post and 24 h after the FIRP. CONCLUSION: FIRP induced acute effects in the jump and sprint performances only. On the other hand, the knee moment production capability (mainly eccentric) suffered acute and also prolonged effects of the FIRP accompanied by delayed muscle soreness in the hamstring muscles. [ABSTRACT FROM AUTHOR]

Resole resins have many applications, especially for foam production. However, the use of phenol, a key ingredient in resoles, has serious environmental and economic disadvantages. In this work, lignin extracted from pine wood using a "green" solvent, levulinic acid, was used to partially replace the non-sustainable phenol. The physicochemical properties of this novel resin were compared with resins composed of different types of commercial lignins. All resins were optimized to keep their free formaldehyde content below 1 wt%, by carefully adjusting the pH of the mixture. Substitution of phenol with lignin generally increases the viscosity of the resins, which is further increased with the lignin mass fraction. The addition of lignin decreases the kinetics of gelification of the resin. The type and amount of lignin also affect the thermal stability of the resins. It was possible to obtain resins with higher thermal stability than the standard phenol-formaldehyde resins without lignin. This work provides new insights regarding the development of lignin-based resoles as a very promising sustainable alternative to petrol-based resins. [ABSTRACT FROM AUTHOR]

The limited stability of catanionic vesicles has discouraged their wide use for encapsulation and controlled release of active substances. Their structure can easily break down to form lamellar phases, micelles or rearrange into multilamellar vesicles, as a consequence of small changes in their composition. However, despite the limited stability, catanionic vesicles possess an attractive architecture, which is able to efficiently encapsulate both hydrophobic and hydrophilic molecules. Therefore, improving the stability of the vesicles, as well as the control on unilamellar structures, are prerequisites for their wider application range. This study focuses on the impact of β-cyclodextrins for the stabilization of SDS/CTAB catanionic vesicles. Molar ratio and sample preparation procedures have been investigated to evaluate the temperature stability of catanionic vesicles. Diffusion and spectroscopic techniques evidenced that when β-cyclodextrins are added, unilamellar structures are stabilized above the multilamellar-unilamellar vesicles critical temperature. The results evidence encouraging perspectives for the use of vesicular nanoreservoirs for drug depot applications. [ABSTRACT FROM AUTHOR]

Viscosupplementation is a therapeutic approach for osteoarthritis treatment, where the synovial fluid, the natural lubricant of the joints, is replaced by viscoelastic solutions with rheological properties comparable or better than the starting material. This study presents the development of an innovative platform for viscosupplementation, based on the optimization of polysaccharide-based colloidal hydrogel, aiming to reduce on-site enzyme degradation and enhance the possibility of hyaluronic acid substitution with alternative biomaterials. Catanionic vesicles are proposed as physical crosslinker that can guarantee the formation of a ‘soft’, tunable network, offering a dual-therapeutic approach: on the mechanical relief perspective, as well as on the drug/gene delivery strategy. This research focuses on the fabrication and optimization of colloidal networks, driven by the synergistic interaction among catanionic vesicles and cationic modified cellulose polymers. This study tests the hypothesis that cellulose-like polymers can be arranged into functional matrix, mimicking the mechanical properties of healthy synovial fluids. [ABSTRACT FROM AUTHOR]

This paper presents an empirical model to predict attenuation in forest environments considering parameters related to vegetation. Typically, environmental parameters are only included in theoretical models, but they are more difficult to apply. The developed model uses tree density, average tree canopy diameter and foliage density as input parameters. The foliage density is very difficult to determine since it depends on the characteristics of trees. A simple metric of this parameter was obtained by measuring the background light silhouetted by the canopy. The model was developed with measurements obtained in different forest environments for two frequencies within the UHF band (Ultra High Frequency). A procedure was also applied to extend the operating frequency range of the model. [ABSTRACT FROM AUTHOR]

Abstract: The role of nonionic vesicles on the rheological behavior of Pluronic F127 is investigated above the dilute regime and below the cloud point of the nonionic surfactant. F127 is a copolymer possessing sol–gel transition by heating attributed to a phase transition from micellar to cubic. The presence of surfactant vesicles is expected to enhance the compartmentalization of a variety of drugs, independently of their affinity to the solvent. Such entrapment would be suitable for controlled release of the drugs in different applications. We address here a mixed Pluronic–nonionic surfactant system with particular emphasis to the effects of the surfactant on the rheological properties of the Pluronics, and the correlation between these properties and drug release control. The results show that the rheological properties of the mixed system are mainly governed by the behavior of the polymer alone and that the mixed system can be useful to control the percutaneous permeation of a small drug, such as Diclofenac Sodium salt. [Copyright &y& Elsevier]

Abstract: The interaction between an anionic surfactant (sodium dodecyl sulfate (SDS)) and an uncharged polymer (hydroxypropylmethyl cellulose) in aqueous solutions has been studied using conductivity, rheology and UV–vis transmittance methods. The effect of hydroxypropylmethyl cellulose (HPMC) concentration on the critical association concentration (cac) of the surfactant and on the polymer saturation points (psp) was analyzed using an electrical conductivity technique, which allowed establishing association and micellization thermodynamic parameters at different polymer concentrations. The effect of temperature on these parameters was also investigated. It is seen that the free energy change in the association process is constant up to 0.5% HPMC, but increases after this point. A similar behavior is found for the bulk micellization process. It is also seen that the association process becomes more and more favorable as the temperature increases. Rheological measurements were performed to investigate the influence of surfactant concentration in the viscosity of HPMC hydrogels at room temperature. Three regimes were found: an initial decrease, up to the cac, followed by a drastic increase and a further decrease starting close to the psp. Studies with temperature ramps have been also conducted to assess the effect of SDS on the thermal gelation of HPMC, showing that SDS delays or even inhibits gelation. Optical transmittance studies were carried out in order to evaluate the behavior of the polymer chains (extension and compaction) as a function of SDS concentration. A model for HPMC–SDS interaction has been proposed, rationalizing the development of the system at different SDS and HPMC concentrations. [Copyright &y& Elsevier]

Abstract: Mixed polymer–surfactant systems have been intensively investigated in the last two decades, with the main focus on surfactant micelles as the surfactant aggregate in interaction. The main types of phase behavior, driving forces and structural/rheological effects at stake are now fairly well understood. Polymer–vesicle systems, on the other hand, have received comparatively less attention from a physico-chemical perspective. In this review, our main goal has been to bridge this gap, taking a broad approach to cover a field that is in clear expansion, in view of its multiple implications for colloid and biological sciences and in applied areas. We start by a general background on amphiphile self-assembly and phase separation phenomena in mixed polymer–surfactant solutions. We then address vesicle formation, properties and stability not only in classic lipids, but also in various other surfactant systems, among which catanionic vesicles are highlighted. Traditionally, lipid and surfactant vesicles have been studied separately, with little cross-information and comparison, giving duplication of physico-chemical interpretations. This situation has changed in more recent times. We then proceed to cover more in-depth the work done on different aspects of the associative behavior between vesicles (of different composition and type of stability) and different types of polymers, including polysaccharides, proteins and DNA. Thus, phase behavior features, effects of vesicle structure and stability, and the forces/mechanisms of vesicle–macromolecule interaction are addressed. Such association may generate gels with interesting rheological properties and high potential for applications. Finally, special focus is also given to DNA, a high charge polymer, and its interactions with surfactants, and vesicles, in particular, in the context of gene transfection studies. [Copyright &y& Elsevier]

Abstract: Vesicles composed of sodium oleate (NaO) and monoolein (MO) are adequate candidates for drug nanoencapsulation and controlled release due to their stability and perceived biocompatibility. The object of the present study is to design hydrogels based on those anionic vesicles and polymers of both non-associative and associative type. The selected macromolecules were k-carrageenan (KC), carboxymethyl cellulose (CMC) and hydrophobically modified carboxymethyl cellulose (HMCMC). While the polymer-vesicle association was probed by rheology, the influence of the polymer on the vesicle stability was monitored by cryo-TEM and calorimetric measurements. The effects of the polymer on the rheological properties of surfactant aggregate solutions clearly depend on the polymer type: the storage moduli of the polymer–vesicle mixtures, compared to the vesicles alone, increases around 2 orders of magnitude if the polymer is non-associative and 4 orders of magnitude if the macromolecule is of associative type. As the vesicles are added, the non-associative polymer networks tend to be disrupted, while the networks formed by associative polymer get more robust. These observations can be explained by fundamental changes in electrostatic/hydrophobic interactions: vesicles entrapped in KC networks convert the polysaccharide in a highly charged entity and favor high electrostatic repulsions between the chains; this encourages network collapse. The opposite picture is experienced in HMCMC systems, i.e., such network is stabilized by the presence of vesicles. This is ascribed to the enhanced hydrophobic association, compensating the electrostatic repulsions between vesicles and polymer chains. [Copyright &y& Elsevier]

Abstract: The knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of shear-rheology, NMR-diffusometry, optical polarizing microscopy and differential scanning calorimetry. The preparation of NaO/water mixtures in this work fitted with the interesting regions of the phase diagrams where most of the new systems will be prepared (i.e. from 0.01 to 30wt.% NaO and within the temperature range 5–70°C). Steady shear and linear viscoelastic experiments were accurately performed and the relationship between phase morphology and rheological properties was also studied. Regarding the mixtures at low surfactant concentrations, the shear flow showed: (1) a structural evolution into the liquid micellar phase (L1) as a function of composition and (2) the presence of a viscous micellar region () induced by temperature and composition changes. NaO/water mixtures with a liquid-crystalline structure (hexagonal H1) were studied by linear shear deformations and paying particular attention to frequency and temperature scans. Viscoelastic spectra of H1 phase presented a gel-like response which, although not expected, indicated the presence of a stiff liquid-crystalline lattice. Finally, a correlation between rheology and microstructural changes was conducted by the “weak-gel” model. [Copyright &y& Elsevier]

Vesicles composed of an anionic and a cationic surfactant, with a net negative charge, associate strongly with a hydrophobically modified polycation (LM200) and with an unmodified polycation with higher charge density (JR400), forming viscoelastic gel-like structures. Calorimetric results show that in these gels, LM200 induces a rise of the chain melting temperature (Tm) of the vesicles, whereas JR400 has the opposite effect. For both polymer−vesicle systems, the shear viscosity exhibits an inflection point at Tm, and for the LM200 system the measured relaxation times are significantly higher below Tm. The neat vesicles and the polycation-bound vesicles have a polygonal-like faceted shape when the surfactant chains in the bilayer are crystallized, as probed by cryo-transmission electron microscopy. Above Tm, the neat and the LM200-bound vesicles regain a spheroidal shape, whereas those in the JR400 system remain with a deformed faceted shape even above Tm. These shape changes are interpreted in terms of different mechanisms for the polymer−vesicle interaction, which seem to be highly dependent on polymer architecture, namely charge density and hydrophobic modification. A crystallization−segregation mechanism is proposed for the LM200−vesicle system, while, for the JR400−vesicle one, charge polarization−lateral segregation effects induced by the polycation in the catanionic bilayer are envisaged. [ABSTRACT FROM AUTHOR]

Hydrophobically modified polymers (HM-P) typically behave as thickeners in a wide range of systems. The thickening effect in an aqueous solution of this kind of polymer depends on intermolecular hydrophobic associations and also on chain entanglements if the polymer concentration is significantly above the overlap concentration. In the present investigation a rather short end-capped polymer has been investigated at concentrations that are significantly below the overlap concentration. Despite the rather low polymer concentration, polymer chains were connected into a three-dimensional network by using microemulsion droplets as cross-linking points. The simple structure of the solution simplifies interpretations of results since chain entanglements can be expected to be of low importance and only intermolecular hydrophobic associations have to be considered. In particular the rheological response is in most cases well characterized by one single relaxation time and, then, the solution can be rationalized within the framework of the Maxwell model. We have found that the length of the polymer chain''s hydrophobic end-groups, as well as the temperature, have a large influence on dynamics of the system, while the length of the hydrophilic mid-block has a relatively small significance. On the other hand, the connectivity in the system depends critically on the microemulsion concentration. Thus, a maximum was found in viscosity as a function of volume fraction, interpreted as being due to a decrease in crosslink lifetime. [Copyright &y& Elsevier]

S100B is an astrocytic extracellular Ca2+-binding protein implicated in Alzheimer's disease, whose role as a holdase-type chaperone delaying Aβ42 aggregation and toxicity was recently uncovered. Here, we employ computational biology approaches to dissect the structural details and dynamics of the interaction between S100B and Aβ42. Driven by previous structural data, we used the Aβ25–35 segment, which recapitulates key aspects of S100B activity, as a starting guide for the analysis. We used Haddock to establish a preferred binding mode, which was studied with the full length Aβ using long (1 μs) molecular dynamics (MD) simulations to investigate the structural dynamics and obtain representative interaction complexes. From the analysis, Aβ-Lys28 emerged as a key candidate for stabilizing interactions with the S100B binding cleft, in particular involving a triad composed of Met79, Thr82 and Glu86. Binding constant calculations concluded that coulombic interactions, presumably implicating the Lys28(Aβ)/Glu86(S100B) pair, are very relevant for the holdase-type chaperone activity. To confirm this experimentally, we examined the inhibitory effect of S100B over Aβ aggregation at high ionic strength. In agreement with the computational predictions, we observed that electrostatic perturbation of the Aβ-S100B interaction decreases anti-aggregation activity. Altogether, these findings unveil features relevant in the definition of selectivity of the S100B chaperone, with implications in Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Food contamination due to the presence of microorganisms is a serious problem. New food preservation systems are being studied to kill or inhibit spoilage and pathogenic microorganisms that contaminate food and reduce the shelf life of products. Chitosan films with potential application to food preservation have witnessed great developments during the last years. Chitosan is a cationic polysaccharide with the ability to form films and possess antimicrobial properties. It is water-insoluble but can be dissolved in acidic solutions. In the present work, three different acids (acetic, lactic and citric) were used in chitosan dissolution and both, the resultant solutions and formed films were characterized. It was observed that chitosan water-acetic acid systems show the highest antimicrobial activity due to the highest chitosan charge density, compared to the mixtures with lactic and citric acid. This system showed also the higher solution viscosity compared to the other systems. Chitosan–acetic acid films were also the ones presenting better mechanical properties; this can be attributed to the fact that lactic and citric acids remain in the films, changing their properties, which does not happen with acetic acid. Films produced from chitosan dissolved in water/acetic acid system are resistant, while very fragile but elastic films are formed when lactic acid is used. It was demonstrated that a good selection of the type of acid not only facilitates the dissolution of chitosan but also plays a key role in the properties of the formed solutions and films. [ABSTRACT FROM AUTHOR]

Catanionic vesicles are emerging interesting structures for bioapplications. They self-generate by a pairing of oppositely charged ionic surfactants that assemble into hollow structures. Specifically, the anionic-cationic surfactant pair assumes a double-tailed zwitterionic behavior. In this work, the multilamellar-to-unilamellar thermal transition of several mixed aqueous systems, with a slight excess of the anionic one, were investigated. Interestingly, it was found that the anionic counterion underwent a dissociation as a consequence of a temperature increase, leading to the mentioned thermal transition. The present work proposed the spectroscopic techniques, specifically multinuclear NMR and PGSTE (pulsed gradient stimulated echo), as a key tool to study such systems, with high accuracy and effectiveness, while requiring a small amount of the sample. The results presented herein evidence encouraging perspectives, forecasting the application of the studied vesicular nanoreservoirs, for e.g., drug delivery. [ABSTRACT FROM AUTHOR]

This study focussed on the development of fully biodegradable composites based on polybutylene succinate (PBS) in combination with raw materials from different processing stages of the pulp and paper industry. Sulfite pulp (SP), kraft pulp (KP) and screened sludge residue (SL) from wastewater treatment plants (WWTP) were investigated as reinforcing fibres contributing to a circular economy. We report a comparative study of the physicochemical properties and mechanical performance of PBS composites reinforced with these cellulosic raw fibres and commercial pure microcrystalline cellulose (MC). The composites were characterised in tensile strength, elongation at break, modulus of elasticity, water absorption and wettability. The incorporation of the fibres into the polymer matrix was also investigated using torque rheometry. Critical concentrations were obtained with maximum incorporation in the range of 15–20 wt% for SP/KP and 25–30 wt% for SL. SP and KP composites showed at least as good physicochemical and mechanical properties as MC at the concentrations studied (0–20 wt%). SP-composites showed the highest tensile strength and modulus of elasticity. It was shown that these fibres from the pulp and paper industry can be used as reinforcement for PBS matrices without additional chemical purification and provide a valuable alternative to commercial microcrystalline cellulose. [ABSTRACT FROM AUTHOR]

Interpolation error is a major source of uncertainty in the calibration of standard platinum resistance thermometer (SPRT) in the subranges of the International Temperature Scale of 1990 (ITS-90). This interpolation error arises because the interpolation equations prescribed by the ITS-90 cannot perfectly accommodate all the SPRTs natural variations in the resistance–temperature behavior, and generates different forms of non-uniqueness. This paper investigates the type 3 non-uniqueness for fourteen SPRTs of five different manufacturers calibrated over the water–zinc subrange and demonstrates the use of the method of divided differences for calculating the interpolation error. The calculated maximum standard deviation of 0.25 mK (near 100∘C) is similar to that observed in previous studies. [ABSTRACT FROM AUTHOR]

S100B is an extracellular protein implicated in Alzheimer's Disease and a suppressor of amyloid-β aggregation. Herein we report a mechanism tying Cu2+ binding to a change in assembly state yielding disulfide cross-linked oligomers with higher anti-aggregation activity. This chemical control of chaperone function illustrates a regulatory process relevant under metal and proteostasis dysfunction as in neurodegeneration. [ABSTRACT FROM AUTHOR]

Abstract Mixtures containing ether sulfate based surfactants (SLE n S) and linear alkylbenzene sulfonic acid (LAS) are relatively common in personal care and household products. When in mixture, they form mixed micelles, which act as reservoirs for the cleaning process. The increase of ethylene oxide (EO) units in the head of SLE n S lowers the critical micelle concentration, meaning that less quantity of each surfactant is needed to form the micelles. Within an eco-friendly perspective this is advantageous since less chemicals are expected to be released into the environment. But, this advantage will only be effective if variations with the higher number of EO units exhibit a lower toxicity as well. Despite its wide use in commercial products, the ecotoxicity of these micelles and the influence of the EO units on their toxicity still did not receive the necessary attention. In this context, the present study aimed at assessing the influence of the number of ethylene oxide (EO) units in the head groups of SLE n S on the toxicity of the SLE n S-LAS mixed micelles to the bacterium Vibrio fischeri (Microtox® assay, here used as a fast and preliminary ecotoxicological indicator). The SLE n S variants with fewer EO units showed higher toxicity relatively to those with more EO units - EC 50 range (0–50 EO units): 0.56–8.59 mg L−1, thus they can be suggested as environmentally safer variants to be used in personal care and household products. Provided the consistency of Microtox® results as obtained here, this quick and cost-effective procedure can be an important tool towards the development of eco-friendlier surfactant-based formulations. Graphical abstract Unlabelled Image Highlights • Toxicity to Vibrio fisheri of seven variations of SLE n S-LAS mixed micelles was studied. • Variations with higher ethylene oxide (EO) groups exhibited lower toxicity. • Lower CMC of the variations with higher EO groups suggest a reduced release of these surfactants to the environment. • Microtox revealed to be an adequate tool in the development of eco-friendlier surfactant formulations. [ABSTRACT FROM AUTHOR]

An abstract of the article "Characterization of Severe Plasmodium Falciparum Malaria Patients in an Angolan General ICU," by Esmael Tomás and colleagues, presented at the conference titled "Parasite to Prevention: Advances in the Understanding of Malaria" held in Edinburgh, Great Britain from October 20-22, 2010, is presented.

Phenolic foams are typically produced from phenolic resins, using phenol and formaldehyde precursors. Therefore, common phenolic foams are non-sustainable, comprising growing environmental, health, and economic concerns. In this work, lignin extracted from pine wood residues using a "green" levulinic acid-based solvent, was used to partially substitute non-sustainable phenol. The novel engineered foams were systematically compared to foams composed of different types of commercially available technical lignins. Different features were analyzed, such as foam density, microstructure (electron microscopy), surface hydrophilicity (contact angle), chemical grafting (infrared spectroscopy) and mechanical and thermal features. Overall, it was observed that up to 30 wt% of phenol can be substituted by the new type of lignin, without compromising the foam properties. This work provides a new insights on the development of novel lignin-based foams as a very promising sustainable and renewable alternative to petrol-based counterparts. [ABSTRACT FROM AUTHOR]

During the last decades, the demand for sustainable and renewable resources has greatly increased. It is clear that biomass exploitation in general, and lignin in particular, will play a key role toward a sustainable and environmental prosperous society. Lignin is a three-dimensional amorphous polymer, mainly found in the cell wall of woody tree species, quite abundant and renewable natural bioresource capable to become in the near future a usual chemical feedstock for many materials of added value. However, its physicochemical understanding is still poor in comparison to other polymers, most likely due to its complexity. Its dissolution, as an often required first step for several production processes and applications, is typically complicated. Nevertheless, a wide variety of solvents for lignin have already been developed and, among them, organic solvents, ionic liquids and deep eutectic solvents are particularly relevant. In this brief treatise, the general features of lignin dissolution are reviewed as the drawbacks and virtues of lignin solvents and appropriate dissolution conditions. [ABSTRACT FROM AUTHOR]

Malignant melanoma (MM) is currently the fastest increasing malignancy and constitutes a major public health burden. The number of common naevi (CN) is known to be related to the MM risk and may serve as a marker in epidemiological studies. For the KORA, Cooperative Health Research in the region of Augsburg, Germany, Survey 2000, a random sample stratified by age and gender of the adult population of the city of Augsburg was drawn. CN are frequent in the adult general population and their number depends on demographic, body metric, and genetic factors as well as parameters of an individual ultraviolet exposure.

The aim of the present work was to modify the exuded gum of Sterculia striata tree by an amination reaction. The viscosity and zero potential of the chicha gum varied as a function of pH. The modification was confirmed by X-ray diffraction (XRD), infrared spectroscopy (FTIR), size exclusion chromatography (SEC), zeta potential, thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Furthermore, the chemical modification changed the molar mass and surface charge of the chicha gum. In addition, the gums were used in tests for ex vivo mucoadhesion strength, antibacterial activity against the standard strain of Staphylococcus aureus (ATCC 25923), inhibitory activity of α-glucosidase, antioxidant capacity, and viability of Caco-2 cells. Through these tests, it was found that amination caused an increase in the mucoadhesive and inhibitory activity of chicha gum against the bacterium Staphylococcus aureus. In addition, the gums (pure and modified) showed antioxidant capacity and an inhibitory effect against the α-glucosidase enzyme and did not show cytotoxic potential. • The exuded gum from the Sterculia striata tree was chemically modified by an amination reaction. • Chemical modification of the gum was confirmed by XRD, FTIR, SEC, zeta potential and thermal analysis (TG/DTG/DSC). • Chicha gum aminated showed an increase in mucoadhesive and inhibitory activity against Staphylococcus aureus bacteria. • The chicha gum and modified gum showed no cytotoxic potential. [ABSTRACT FROM AUTHOR]

Cellulose is insoluble in water but can be dissolved in strong acidic or alkaline conditions. How well dissolved cellulose is in solution and how it organizes are key questions often neglected in literature. The typical low pH required for dissolving cellulose in acidic solvents limits the use of typical characterization techniques. In this respect, Polarization Transfer Solid State NMR (PT ssNMR) emerges as a reliable alternative. In this work, combining PT ssNMR, microscopic techniques and X-ray diffraction, a set of different acidic systems (phosphoric acid/water, sulfuric acid/glycerol and zinc chloride/water) is investigated. The studied solvent systems are capable to efficiently dissolve cellulose, although degradation occurs to some extent. PT ssNMR is capable to identify the liquid and solid fractions of cellulose, the degradation products and it is also sensitive to gelation. The materials regenerated from the acidic dopes were found to be highly sensitive to the solvent system and to the presence of amphiphilic additives in solution. [ABSTRACT FROM AUTHOR]

Cleaning products have a global market of around $33 billion in 2020 and play an essential role in daily life, providing consumers with important public health benefits. Surfactants are the main ingredients of cleaning products and they can effectively remove dirt, germs, and other contaminants from surfaces. Understanding the role of each surfactant class in a detergent formulation and their interaction with NaCl is of utmost importance for formulating efficient and sustainable cleaning products. This paper describes the study of ternary surfactant systems consisting of surfactants (sodium lauryl ether sulfate, alkyl polyglycoside, or betaine, three of the most commonly used surfactants in detergent formulations), water, and NaCl. The effects of concentration on critical micelle concentration, aggregate size, and rheological behavior were evaluated by dynamic light scattering and rheology techniques. [ABSTRACT FROM AUTHOR]

The development of strategies for dissolution and regeneration of cellulose constitutes an increasingly active research field due to the direct relevance for many production processes and applications. A wide variety of suitable solvents for cellulose are already available. However, cellulose solvents are of highly different nature reflecting the great challenges in the understanding of the subtle balance between the different interactions. Here, we report on the effect of two different solvents on the dissolution of cellulose on multiple length scales and its consequences for the characteristics of the regenerated material. While an aqueous tetrabutylammonium hydroxide solution gives rise to what appears to be dissolution down to the molecular level, a sodium hydroxide solution does not dissolve cellulose molecularly but rather leaves aggregates of high crystallinity stable in the cellulose dope. The dramatic difference between a small inorganic cation and an amphiphilic cation indicates a critical role of hydrophobic interactions between cellulose molecules and provides support for the picture that cellulose molecules have pronounced amphiphilic properties. [ABSTRACT FROM AUTHOR]

Unlike many nanomaterials, nanocrystalline cellulose (CNC) is not synthesized from molecular or atomic components but rather extracted from naturally occurring cellulose. Undoubtedly, the exploitation of CNCs will become a bridge between nanoscience and natural resource products, which could play a major role in reviving the forest industry. In this work, CNC was successfully extracted from unusual sources, hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC). The extracted crystallites were purified and further characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and dynamic light scattering (DLS). The average size of the CNCs extracted from HPMC and CMC was found to be less (and with lower zeta potential) than the ones extracted from microcrystalline cellulose (MCC). On the other hand, FTIR and XRD revealed that native HPMC and CMC are unexpectedly highly crystalline and hence can be used as a source for CNCs. [ABSTRACT FROM AUTHOR]

The control over the Low Critical Solution Temperature (LCST) and thickening of thermosensitive polymers is of crucial interest for applications such as drug delivery systems and temperature sensors. Commonly the design of a new drug delivery system of a temperature sensor requires the synthesis of new thermosensitive polymers that respond to a desired target temperature. In this study we follow the LCST by rheology and report examples of how the onset of LCST can be adjusted by chemical species that are able to change polymer solubility, such as salts, organic solvents or surfactants. For this purpose we used the thermo-responsive polymer, poly(N-isopropyl acrylamide) or PNIPAM, and surfactants, salts and ethanol as additives. The LCST was investigated by means of rotational rheology, as it has been shown a good correlation between the LCST and the onset of the temperature-induced thickening. From this study we observe that salts can both increase or decrease the temperature at which the LCST occurs. This is attributed to the affinity of the different salts with the polymer. More hydrophobic salts such as KSCN shifted the LCST of PNIPAM to higher temperature values while the opposite scenario is observed in the case of more hydrophilic salts such as KCl. When surfactants are added to the system, it is observed that, in both cases (SDS and CTAB) and at the concentrations employed, the LCST was shifted to higher temperatures. Surfactants interact with the polymeric chains, converting the macromolecule into a polyelectrolyte and retarding the occurrence of clouding or phase separation. Major effects were also observed by changing the polarity of the bulk: the presence of 10% ethanol shifted the LCST of PNIPAM solution to lower temperatures, forming a co-non-solvent pair with water. No phase transition was observed when PNIPAM was dissolved in absolute ethanol. These observations highlight the role of hydrophobic associations and the entropy of counterions. [ABSTRACT FROM AUTHOR]

Abstract: In this work we present an analysis of the thermal behavior of hydroxypropylmethyl cellulose aqueous solutions, from room temperature to higher temperatures, above gelation. We focus on significant aspects, essentially overlooked in previous work, such as the correlation between polymer hydrophobicity and rheological behavior, and the shear effect on thermal gelation. Micropolarity and aggregation of the polymer chains were monitored by both UV/vis and fluorescence spectroscopic techniques, along with polarized light microscopy. Gel formation upon heating was investigated using rheological experiments, with both large strain (rotational) tests at different shear rates and small strain (oscillatory) tests. The present observations allow us to compose a picture of the evolution of the system upon heating: firstly, polymer reptation increases due to thermal motion, which leads to a weaker network. Secondly, above 55 °C, the polymer chains become more hydrophobic and polymer clusters start to form. Finally, the number of physical crosslinks between polymer clusters and the respective lifetimes increase and a three-dimensional network is formed. This network is drastically affected if higher shear rates, at non-Newtonian regimes, are applied to the system. [Copyright &y& Elsevier]

Abstract: The association between hydrophobically modified polyethylene glycol, HM-PEG, and non-ionic vesicles of tetraethylene glycol monododecyl ether, C12E4, was investigated. HM-PEG is in a triblock form, with an alkyl chain attached to each hydrophilic polymer-end. Such polymer structure is denoted as telechelic. The vesicle average radius was measured by self-diffusion measurements. The system exhibits both a monophasic gel and biphasic regions. The monophasic region was characterized from a rheological point of view. We argue that the gel formation is due to the presence of polymer crosslinks between different surfactant aggregates, once the polymer''s hydrophobic moieties may adsorb into the vesicle bilayer. This association is strongly concentration dependent which is reflected in the monotonic increase of the storage modulus, relaxation time and shear viscosity with the addition of surfactant and/or polymer. [Copyright &y& Elsevier]

Abstract: Micropipettes or piston pipettes are used to make the most of volume measurements in fields like health, chemistry, biology, pharmacy and genetics. Laboratories must ensure that obtained results using these instruments are reliable, for that is necessary to calibrate micropipettes using the correct method and estimate uncertainties. The objective of this work is to present the best method to calibrate micropipettes according to the describe measurement conditions. A model for the calculation of the measurement uncertainty is also described. [Copyright &y& Elsevier]

BACKGROUND: Repetitive stretch-shortening cycle exercises generate high rates of mechanical work and consequently induce substantial muscular fatigue related to delayed neuromuscular functions. OBJECTIVE: To investigate the neuromuscular impairment after high-intensity exercise protocols involving different gravity loads in stretch-shortening cycle – running (RUN) and vertical jumps (VJ). METHODS: Twenty-two healthy men, divided into two groups, VJ and RUN participated in this study. The individuals performed a training session involving six bouts of 30 s of VJ or RUN. The isokinetic PM (PM) of the knee extensors and flexor muscles, rate of perceived exertion and delayed onset muscle soreness (DOMS) were evaluated at pre, post, 24 h and 48 h post-training. RESULTS: The concentric and eccentric PM of the extensor in the RUN group was reduced until 24 h, while in the VJ a decrement was observed until 48 h. Following running, the PM of the flexors decreased until 48 h, while for VJ there was an eccentric PM decrement at 48 h. The DOMS increased at the anterior thigh and only after VJ training for 48 h. CONCLUSION: Acute and delayed neuromuscular impairment may be observed after both exercise regimens, but high-intensity training using vertical jumps seems to induce a more pronounced impairment than running. [ABSTRACT FROM AUTHOR]

The dissolution and extraction of lignin from biomass represents a great challenge due to the complex structure of this natural phenolic biopolymer. In this work, several surfactants (i.e., non-ionic, anionic, and cationic) were used as additives to enhance the dissolution efficiency of model lignin (kraft) and to boost lignin extraction from pine sawdust residues. To the best of our knowledge, cationic surfactants have never been systematically used for lignin dissolution. It was found that ca. 20 wt.% of kraft lignin is completely solubilized using 1 mol L−1 octyltrimethylammonium bromide aqueous solution. A remarkable dissolution efficiency was also obtained using 0.5 mol L−1 polysorbate 20. Furthermore, all surfactants used increased the lignin extraction with formic acid, even at low concentrations, such as 0.01 and 0.1 mol L−1. Higher concentrations of cationic surfactants improve the extraction yield but the purity of extracted lignin decreases. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is a renewable and sustainable feedstock, mainly composed of cellulose, hemicellulose, and lignin. Lignin, as the most abundant natural aromatic polymer occurring on Earth, has great potential to produce value-added products. However, the isolation of highly pure lignin from biomass requires the use of efficient methods during lignocellulose fractionation. Therefore, in this work, novel acidic deep eutectic solvents (DESs) were prepared, characterized and screened for lignin extraction from maritime pine wood (Pinus pinaster Ait.) sawdust. The use of cosolvents and the development of new DES were also evaluated regarding their extraction and selectivity performance. The results show that an 1 h extraction process at 175 °C, using a novel DES composed of lactic acid, tartaric acid and choline chloride, named Lact:Tart:ChCl, in a molar ratio of 4:1:1, allows the recovery of 95 wt% of the total lignin present in pine biomass with a purity of 89 wt%. Such superior extraction of lignin with remarkable purity using a "green" solvent system makes this process highly appealing for future large-scale applications. [ABSTRACT FROM AUTHOR]

Lignin is a natural, renewable resource with potential to be used in biomaterials. Due to its complex structure, its efficient dissolution is still challenging, which hinders its applicability at large scale. This challenge become harder considering the current need of sustainable and environmentally friendly solvents. To the best of our knowledge, this work reports for the first time the dissolution of kraft lignin in levulinic acid, a "green" solvent, and compares its efficiency with common carboxylic acids and sulfuric acid. It has been found that levulinic acid has a high capacity to dissolve kraft lignin at room temperature (40 wt% solubility), and it efficiency is not compromised when diluting the acid with water (up to 40 wt% water content). The Kamlet-Taft π⁎ parameter of the different acidic solvents was estimated and found to correlate well with their solubility performance. Lignins previously dissolved in levulinic and formic acids were selected to be regenerated and minor differences were found in thermal stability and morphological structure, when compared to native kraft lignin. However, an increase in the content of the carbonyl groups in the regenerated lignin material was observed. [ABSTRACT FROM AUTHOR]

Lignins are among the most abundant renewable resources on the planet. However, their application is limited by the lack of efficient dissolution and extraction methodologies. In this work, a systematic and quantitative analysis of the dissolution efficiency of different alkaline-based aqueous systems (i.e. lithium hydroxide, LiOH; sodium hydroxide, NaOH; potassium hydroxide, KOH; cuprammonium hydroxide, CuAOH; tetrapropylammonium hydroxide, TPAOH and tetrabutylammonium hydroxide, TBAOH) is reported, for the first time, for kraft lignin. Phase maps were determined for all systems and lignin solubility was found to decrease in the following order: LiOH > NaOH > KOH > CuAOH > TPAOH > TBAOH, thus suggesting that the size of the cation plays an important role on its solubility. The π ∗ parameter has an opposite trend to the solubility, supporting the idea that cations of smaller size favor lignin solubility. Dissolution was observed to increase exponentially above pH 9–10 being the LiOH system the most efficient. The soluble and insoluble fractions of lignin in 0.1 M NaOH were collected and analyzed by several techniques. Overall, data suggests a greater amount of simple aromatic compounds, preferentially containing sulfur, in the soluble fraction while the insoluble fraction is very similar to the native kraft lignin. • Several alkaline-based solvents were used to dissolve kraft lignin. • The size of the cation was found to play an important role on lignin solubility. • Low polarizability of the solvent favors the lignin solubility. • The soluble lignin fraction has a greater amount of simple aromatic compounds. • The soluble lignin fraction has a higher sulfur content than the insoluble fraction. [ABSTRACT FROM AUTHOR]

Abstract Global environmental concerns on the production, usage and disposal of multiple human-made products have encouraged the study and development of new more ecological materials based on or inspired by biomolecules that may ultimately replace the current existing options. These efforts include the development of sugar-based surfactants. They have been increasingly adopted in selected applications to replace conventional surfactants. Sorbitan ester is a good example of a sugar-based surfactant already in use in the food industry as an emulsifier agent. However, in aqueous solution, the use of this type of surfactants is highly limited as nanocompartments due to their low water solubility. This problem can be overcome by using the alcohol injection method (AIM), where a small amount of alcohol is mixed with the surfactant in water to produce dispersed vesicles. Since the formation of sorbitan ester vesicles are of enormous interest for the nanoencapsulation of active substances for various applications, from food to cosmetics and pharmaceuticals, it is crucial to develop efficient ways to produce these aggregates via the alcohol injection method. The present work reports a study of the role of the alcohol structure on the formation of nanostructures of sorbitan ester. Methanol, ethanol and 2-propanol were selected to evaluate the influence of the alcohol alkyl chain length on the formation and stabilization of the vesicles. Some of the alcohol solutions were evaporated in order to probe the stability of the aggregates even after alcohol removal. Analysis by dynamic light scattering (DLS) and 1H NMR have shown a direct relation between the size of the alcohol's alkyl chain and the size of the formed sugar-based vesicles. Additionally, it is clear that the alcohol molecules remain in the vesicle, even after the evaporation process. The obtained results demonstrate that it is possible to control the size of the sugar-based sorbitan ester vesicles using the alcohol injection method. Hopefully, this research will encourage and enable the use of nanocompartments in a wider range of applications. Graphical abstract Unlabelled Image Highlights • Sugar-based vesicles can be produced by alcohol injection method. • The injected solvent promotes the selfassembly of the amphiphiles. • Vesicle size can be controlled by alcohol structure. • Lipophilic character of Span surfactants can be reverted by alcohol injection method. [ABSTRACT FROM AUTHOR]

Hypothesis The rheological control of suspensions is of key interest in the formulation design. A chemically cross-linked hydrophobically modified poly(acrylic acid) (HMCL-PAA), used as rheology modifier, is pH sensitive and shows swelling behavior above a critical pH due to the ionization of the acrylic acid groups. At low pH, HMCL-PAA suspensions are liquid and turbid. The binding of surfactants to HMCL-PAA, at low pH conditions, can result in significant changes on rheology and transparency of the polymeric suspensions, due to the swelling of the microgel particles. Experiments The influence of surfactants addition on the rheological properties and transparency of HMCL-PAA suspensions was determined. A systematic study was performed using different types of surfactants (ionic, non-ionic and zwitterionic). Findings The gelation efficiency of HMCL-PAA suspensions at low pH is strongly dependent on surfactant architecture: ionic surfactants are found to be much more efficient than non-ionic or zwitterionic surfactants. Ionic surfactants lead to a liquid-to-gel transition accompanied by an increase of transparency of the suspensions. Among the ionic surfactants, anionics show stronger interactions with the polymer. Also the surfactant hydrophobicity is relevant; the more hydrophobic the surfactant, the stronger is the binding to the polymer and thus the larger the particle swelling. [ABSTRACT FROM AUTHOR]

An innovative technique for pancreas transplantation is described. The main aspect consists of the horizontal positioning of the pancreas, which allows a better venous outflow, thus preventing thrombosis and graft loss. The program of pancreas transplantation in this national reference center for pancreatic and liver surgery was started in 2007; the initial results were considered poor, resulting in the loss of half of the grafts due to venous thrombosis. After analyzing the possible causes, this technique was proposed and successfully implemented, reducing the postoperative complications, particularly the problem of venous thrombosis. A detailed description of the new surgical technique is provided. The main clinical and demographic characteristics of the 56 patients who underwent the surgery are analyzed. The incidence of venous thrombosis was 5.3% (3 patients) and graft loss was 3.5% (2 patients). Due to the good results, this technique became the standard surgery for transplantation of the pancreas in our center. The technique proved to be safe and successful. Due to the unique pancreas graft implantation, we called it “transverse pancreas surgery.” [ABSTRACT FROM AUTHOR]

In this work, new amphiphilic diblock copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(4-vinylpyridine) (P4VP) as anchoring blocks, and poly(acrylic acid) (PAA) as outer block, have been synthetized and evaluated as tailor-made polymeric dispersants of TiO 2 particles in aqueous solution. The amphiphilic block copolymers with molecular weight up to 20,000 g/mol were synthetized by atom transfer radical polymerization (ATRP), and the stabilizing effect of the different block segment ratios was studied. These diblock copolymers were fully characterized by size exclusion chromatography (SEC), and nuclear magnetic resonance analysis ( 1 H NMR). The success of the polymeric dispersant adsorption onto TiO 2 particles was confirmed by a clear change on zeta potential (ζ) values (from −1.28 mV of TiO 2 particles to values higher than 25 mV for the block copolymers dispersions) and by an increase of the hydrodynamic diameter determined by dynamic light scattering (DLS). The influence of different block segment lengths in the obtained copolymers was evaluated in aqueous dispersions of TiO 2 and in a common water-based paint formulation. After paint application, the successful dispersion of TiO 2 particles using the amphiphilic block copolymers of PAA 24 - b -P4VP 57 , PAA 72 - b -P4VP 82 , PAA 24 - b -PDMAEMA 16 and PAA 24 - b -PDMAEMA 24 was confirmed by an increase in the gloss (43.8, 41.8, 39.5 and 37.7 g u., respectively), when compared to the commercial reference, Additol VXW 6200 (36.6 g u.). Such features are particularly relevant for the development of polymeric stabilizers to be used as TiO 2 dispersants in paint formulations. [ABSTRACT FROM AUTHOR]

Cellulose dissolution is a challenging process which is typically very sensitive to the solvent characteristics such as pH, temperature or presence of additives. Regarding the later aspect, it is here reported the interaction between α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) with the tetrabutylammonium cation (TBA + ) by 1 H NMR titration experiments. The analysis by the continuous variation method suggests the formation of 1:1 CD:TBA + complexes. However, the computed apparent association constants reveal that the interaction of TBA + with the β-CD ( K = 1580 M −1 ) is unexpectedly stronger than with α-CD ( K = 106 M −1 ). In both CD cases, the formation of CD:TBA + complexes decrease the dissolution efficiency of the solvent and this has been rationalized as an effective decrease in the concentration of the amphiphilic cation and concomitant weakening of the hydrophobic interactions in solution influencing the overall performance of the solvent. Additionally, the data also supports the fact that amphiphilic species in solution are beneficial for the enhancement of cellulose solubility. [ABSTRACT FROM AUTHOR]