Variations on the processing conditions of conventional methods for polymeric film preparation may allow tuning certain properties. In this work, different casting surfaces and humidity are presented as variables to consider for cellulose acetate (CA) film preparation using conventional solution casting method. Specifically, borosilicate glass, soda-lime glass and Teflon (PTFE) dishes have been used for casting and their influence on various properties on CA films assessed. The surfaces of glass dishes are smooth, while PTFE surface has a pattern constituted by concentric channels of micro dimensions (as seen by optical microscope), which is adopted by cast films upon drying. The resulting patterned films are translucent while films produced using smooth surfaces are transparent. The effect of the environment humidity (35%, 55% and 75% RH) in the properties of the CA films during the evaporation of solvent from solution has been evaluated. Higher humidity produces smoother surfaces and increased crystallinity as shown by XRD and DSC; however, the wettability of the films does not seem to be influenced by this variable. Due to the specific morphology of the patterned films, changes in material opacity upon wetting are detected, from translucent to transparent, while the removal of water from the surface restores the translucency. This micropatterning effect that causes different visual appearance of the material can find use as a humidity sensor in food packaging applications.

Carreaux de pavement is a type of mediaeval tile common in northwestern Europe, whose method of producing has been unknown until now. In this article, the kiln firing conditions of the unique carreaux de pavement found in the Iberian Peninsula were determined by comparing the physicochemical and mineralogical properties of the archaeological tiles with those of some reproductions of the tile's body manufactured in the laboratory (replica) made by varying the firing temperature and time, as well as the sample size and thickness. The resistance to acid digestion exhibited by the fired samples was especially revealed. According to the results and the modelling performance with the collected data, it was established that the maximum firing temperature was between 900 and 975 °C, and the time was longer than 24 h. These results show the technology used by mediaeval French potters and are a basis for future studies.

Cyclodextrins, cyclic oligosaccharides with a hydrophobic cavity that form inclusion complexes with nonpolar molecules, can be used to functionalize other polysaccharides. Xanthan gum, locust bean gum or chitosan can be crosslinked using citric acid in the presence of ß-cyclodextrin to produce insoluble matrices. In this work, polymeric foams based on those polysaccharides and saponin have been prepared using a green synthesis method to increase the porosity of the matrices. The saponin of soapbark (Quillaja saponaria) has been used to obtain foams using different procedures. The influence of the synthesis path on the porosity of the materials and their corresponding sorption capacities in the aqueous phase were evaluated.

Chitosan-based hydrogels are prepared via the formation of polypseudorotaxanes (PPR), by selectively threading alpha-cyclodextrin (alpha-CD) macrocycles onto polymeric chains, which, through the formation of microcrystalline domains, act as junction points for the network. Specifically, host-guest inclusion complexes are formed between alpha-CD and PEGylated chitosan (PEG-Ch), resulting in the formation of supramolecular gels. PEG-grafted chitosan is obtained with a reaction yield of 79.8%, a high degree of grafting (50.9% GW) and water solubility (approximate to 16 mg mL(-1)), as assessed by turbidimetry. A range of compositions for mixtures of PEG-Ch solutions (0.2-0.8% w/w) and alpha-CD solutions (2-12% w/w, or 0.04-0.2% mol) are studied. Regardless of PEG content, gels are not formed at low alpha-CD concentrations (<4%). Dynamic rheology measurements reveal stiff gels (G' above 15k) and a narrow linear viscoelastic region, reflecting their brittleness. The highest elastic modulus is obtained for a hydrogel composition of 0.4% PEG-Ch and 6% alpha-CD. Steady-state measurements, cycling between low and high shear rates, confirm the thixotropic nature of the gels, demonstrating their capacity to fully recover their mechanical properties after being exposed to high stress, making them good candidates to use as in-situ gel-forming materials for drug delivery to topical or parenteral sites.

Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.). In addition, this hydrocolloid is easily modified by derivatization or crosslinking. These LBG-related products, besides their applications in the food industry, can be used as encapsulation and drug delivery devices, packaging materials, batteries, and catalyst supports, among other biopharmaceutical and industrial uses. As the new derivatized or crosslinked polymers based on LBG are mainly biodegradable and non-toxic, the use of this polysaccharide (by itself or combined with other biopolymers) will contribute to generating greener products, considering the origin of raw materials used, the modification procedures selected and the final destination of the products.

Collagen-based polymers and their blends have attracted considerable interest for new materials development due to their unique combination of biocompatibility, physical and mechanical properties and durability. Leather, a modified natural biopolymer made from animal rawhide and the first synthetic collagen-based polymer known since the dawn of civilization, combines all these features. Rawhide is transformed into leather by tanning, a process in which the collagen is cross-linked with different agents to make it stronger and more durable and to prevent its decay. Research on the development of environmentally friendly procedures and sustainable materials with higher efficiency and lower costs is a rapidly growing field, and leather industry is not an exemption. Chrome-tanned and vegetable-tanned (chromium-free) shavings from the leather industry present a high content of organic matter, yet they are considered recalcitrant waste to be degraded by microbiological processes like anaerobic digestion (AD), a solid technology to treat organic waste in a circular economy framework. In this technology however, the solubilisation of organic solid substrates is a significant challenge to improving the efficiency of the process. In this context, we have investigated the process of microbial decomposition of leather wastes from the tannery industry to search for the conditions that produce optimal solubilisation of organic matter. Chrome-tanned and chromium-free leather shavings were pre-treated and anaerobically digested under different temperature ranges (thermophilic-55 degrees C-, intermediate-42 degrees C- and mesophilic-35 degrees C) to evaluate the effect on the solubilisation of the organic matter of the wastes. The results showed that the presence of chromium significantly inhibited the solubilization (up to 60%) in the mesophilic and intermediate ranges; this is the fastest and most efficient solubilization reached under thermophilic conditions using the chromium-free leather shaving as substrates. The most suitable temperature for the solubilization was the thermophilic regime (55 degrees C) for both chromium-free and chrome-tanned shavings. No significant differences were observed in the thermophilic anaerobic digestion of chromium-free shavings when a pre-treatment was applied, since the solubilisation was already high without pre-treatment. However, the pre-treatments significantly improved the solubilisation in the mesophilic and intermediate configurations; the former pre-treatment was better suited in terms of performance and cost-effectiveness compared to the thermophilic range. Thus, the solubilisation of chromium-free tannery solid wastes can be significantly improved by applying appropriate pre-treatments at lower temperature ranges; this is of utter importance when optimizing anaerobic processes of recalcitrant organic wastes, with the added benefit of substantial energy savings in the scaling up of the process in an optimised circular economy scenario.

In this study, the thermal behavior of a series of leishmanicidal selenocyanate and diselenide biological active compounds has been studied by means of differential scanning calorimetry, X-ray diffraction and thermogravimetry in order to establish thermal stability criteria and investigate their polymorphism. Moreover, stability under acid, alkaline and oxidative media was tested using high-performance liquid chromatography with fluorescence detection. The results of the experiments show that there are five types of polymorphic behaviors for the studied compounds. In addition, relationship is found among stability and a series of structural effects and stress conditions of compounds.

The relationship between processing conditions, structure and morphology are key issues to understanding the final properties of materials. For instance, in the case of polymers to be used as scaffolds in tissue engineering, wound dressings and membranes, morphology tuning is essential to control mechanical and wettability behaviors. In this work, the relationship between the processing conditions of the solution blow spinning process (SBS) used to prepare nonwoven mats of polyethylene oxide (PEO), and the structure and morphology of the resulting materials are studied systematically, to account for the thermal and mechanical behaviors and dissolution in water. After finding the optimal SBS processing conditions (air pressure, feed rate, working distance and polymer concentration), the effect of the solvent composition has been considered. The structure and morphology of the blow spun fibers are studied as well as their thermal, mechanical behaviors and dissolution in water. We demonstrate that the morphology of the fibers (size and porosity) changes with the solvent composition, which is reflected in different thermal and mechanical responses and in the dissolution rates of the materials in water.

This manuscript provided one of the first scientific studies performed on ancient Spanish liturgical vestments by using a multitechnical physicochemical approach. The interlining and lining fabrics were done by cotton and the core of threads by silk. Silver, gold and little amounts of copper were detected. The highest values of gold were found in the metal threads of the cope and the gallon of the chasuble. Two layers were identified: the internal composed by silver and the external by silver and gold. The fibers were proved to be degraded and also the surface of the metal, where scratches and silver-based compounds were detected due to environmental and anthropogenic actions. Indigo was employed as dye in the blue and green fabrics. Wax was detected in the yellow fibers, although other dyes could not be discarded. The materials used in the restoration processes were of minor quality.

Gemfibrozil (GEM) is a hypolipidemic agent, which is effective in reducing serum cholesterol and triglyceride levels. Complexation of GEM with native ß-cyclodextrin (ß-CD) and with the derivatives hydroxypropyl-ß- and randomly methylated ß-CD (HPß-CD and Meß-CD) was studied in aqueous solution of pH 2.8 and 7.0. The stability constants were determined by spectrofluorimetry, 1H-NMR spectroscopy and solubility assays. Considering the well-known difficulties to obtain similar stability constants by different techniques, the agreement of the values obtained supports the reliability of the results presented. The advantages and drawbacks of each analytical technique for the study of inclusion complexation were discussed as well. In addition, the thermodynamic parameters of complexation, enthalpy (¿H) and entropy (¿S), were determined and related to the type of molecular interactions that take place between GEM and the different cyclodextrins. Finally, solid dispersions were prepared by co-evaporation, kneading, vacuum desiccation, and coprecipitation, and complexation was evaluated by X-ray diffraction.

Polylactic acid (PLA) and cellulose acetate (CA) as biodegradable polymers are being highly exploited in the development of innovative materials across several industrial sectors. PLA and CA composite films with TiO2 nanoparticles (NPs) and beta-cyclodextrin grafted TiO2 NPs were prepared. Thermo- and photo-degradation studies were performed on PLA and CA films and noticed that higher amount of TiO2 induce greater color variations, structure modifications and weight losses. It has been observed 9.3 % and 5.1 % maximum weight loss for 5 % TiO2 CA and PLA matrices, respectively. beta CD-modified TiO2 NPs increased the photo-degradation of the plain polymers to a lesser extent than TiO2 NPs. Benzoic acid (BA) and sorbic acid (SA) were incorporated to beta CD-TiO2 NPs and the antibacterial activity of PLA and CA composite films was studied by inactivation of Escherichia coli and Staphylococcus aureus. CA film filled with 5 % TiO2 NPs presented the highest antibacterial activity and achieved 71 % inhibition of E. coli and 88 % inhibition of S. aureus. CA composite films showed potential to be used as antimicrobial food packaging.

The walls of the Alcazar Palace in Seville have been covered with ceramic tiles of different styles that were manufactured with different techniques. Several studies have been carried out on these ceramics, but no interest has been paid to the tiles manufactured by the workshop of the Valladares family, one of the most productive ceramic workshops in Triana (Seville). In this work, tiles that were made in the Valladares workshop are studied for the first time. The tiles from the Cenador del Leon built in 1645-1646 were chosen. The experimental studies suggest that the ceramic body was manufactured with silico-calcareous clay. This raw material was heated to a temperature of ca. 900 degrees C. A nondestructive and on-site analytical procedure was applied first. Microsamples were also taken and studied through microanalytical techniques. The maiolica style was used by Benito de Valladares for tile manufacture. The glaze phases were constituted by two layers. The pigments and doping elements used to obtain different colors were characterized. Valladares' work is considered as a continuation of Augusta's work; therefore, a comparison between both ceramists has been realized to better understand the ceramics production in southern Spain during the sixteenth to seventeenth centuries.

Polysaccharides such as xanthan, locust bean gum or chitosan are easily crosslinked and purified using citric acid in an ecofriendly process. In order to achieve an improved sorption capability towards hydrophobic solutes, B-cyclodextrin, a cyclic oligosaccharide, and lignin, a natural aromatic polymer, are incorporated in the same process. Once crosslinked, the influence of these on the sorption capacities towards model solutes has been assessed by comparing the sorption isotherms of matrices with or without the hydrophobic modifications. The sorption capacities of these materials for different phenolic compounds have also been tested to ascertain their efficiencies as a function of their affinities to B-cyclodextrin cavities and/or their partition coefficients. In addition, these functionalized carbohydrate matrices were successfully characterized by principal component analysis, which is a useful tool to select the most appropriate polymers to interact with a specific molecule.

A cyclodextrin-based polymer was prepared by crosslinking beta-cyclodextrin with epichlorohydrin to be assessed as a sorbent material for cresols in packed-bed columns. Both Langmuir and Freundlich isotherms were appropriate to describe the sorption equilibrium in the conditions tested, and the thermodynamic parameters obtained for this process confirmed its exothermic nature with similar enthalpies (between - 6.8 and - 8.3 kJ/mol) for the three isomers. The removal of cresols from water was carried out in nine cycles of sorption-desorption in fixed-column experiments with the cyclodextrin hydrogel, achieving sorption capacities of 6.2, 11.6, and 15.1 mg/g for o-, m-, p-cresol, respectively. These differences in sorption capacities are due to the different chemical structures of cresols, that is, the relative position of the methyl and hydroxyl groups. However, similar sorption rates were observed for each isomer, with a mean value of 0.10 mg-cresol g-CDP-1 min(-1) in all cases. The experimental data for the breakthrough and the elution curves have been successfully modeled by two effective two-parameter equations, a dose-response model for the sorption step and a pulse-peak model for the regeneration step. The cyclodextrin polymer matrix has been proven to be an effective a good sorbent material for removing cresols from water, exhibiting remarkable reusability performance and structural stability throughout the successive elution steps carried out with methanol.

Pseudopolyrotaxanes (PPRs) are supramolecular structures consisting of macrocycles able to thread on a linear polymer chain in a reversible, non-covalent way, often referred to in the literature as "molecular necklaces". While the synthesis and reaction mechanisms of these structures in solution have been widely described, their solvent-free production has received little attention, despite the advantages that this route may offer. We propose in this work a kinetic mechanism that describes the PPR formation in the solid phase as a process occurring in two consecutive stages. This mechanism has been used to investigate the spontaneous formation of a PPR that occurs when grinding alpha-Cyclodextrin (alpha-CD) with polyethylene glycol (PEG). In the threading stage, the inclusion of the polymer and subsequent release of the water molecules lodged in the cavity of the macrocycle cause vibrational changes that are reflected in the time-dependence of the FTIR-ATR spectra, while the further assembly of PPRs to form crystals produces characteristic reflections in the XRD patterns, due to the channel-like arrangement of CDs, that can be used to track the formation of the adduct in crystalline form. The effects that working variables have on the kinetics of the reaction, such as temperature, feed ratio, molar mass of the polymer and the introduction of an amorphous block in the polymer structure, have been investigated. The rate constants of the threading step increase with the temperature and the activation energy of the process increases at lower proportions of CD to PEG. This is attributed to the lower degree of covering of the polymer chain with CDs that reduces the hydrogen-bonding driven stabilization between adjacent macrocycles. The formation of crystalline PPR, which takes place slowly at room temperature, is markedly promoted at higher temperatures, with lower proportions of CD favoring both the formation and the growth of the crystals. The molar mass of the polymer does not modify the typical channel-like arrangement of packed PPRs but the conversion into crystalline PPR diminishes when using PEG1000 instead of PEG400. At a microscopic level, the crystals arrange into lamellar structures, in the order of hundreds of nm, embedded in an amorphous-like matrix. The introduction of a polypropylene oxide block in the structure of the polymer (Pluronic L62) renders poorer yields and a considerable loss of crystallinity of the product of the reaction. The methodology here proposed can be applied to the general case of inclusion complexes of CDs with drugs in the solid phase, or to multicomponent systems that contain polymers as excipients in pharmaceutical formulations along with CDs.

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view. In food science, applications include debittering of juices, retention of aromas and release of preservatives from packaging. In biomedical science, cyclodextrin polymers are applied classically to drug release, and more recently to gene delivery and regenerative medicine. The remarkable points are: 1) epichlorohydrin and diisocyanates have been extensively used as crosslinkers since the 1960s, but during the last two decades more complex cyclodextrin polymeric structures have been designed. 2) The evolution of cyclodextrin polymers matches that of macromolecular materials with regard to complexity, functionality and capabilities. 3) The use of cyclodextrin polymers as sorbents in the food sector came first, but smart packaging is now an active challenge. Cyclodextrins have also been recently used to design treatments against the coronavirus disease 2019 (COVID-19).

Hypothesis: The combination of polymeric surfactants into mixed micelles is expected to improve properties relevant to their use in drug delivery, such as micellar size, gelation, and toxicity. We investigated synergistic effects in mixtures of D-¿-Tocopheryl polyethylene glycol succinate (TPGS), an FDA-approved PEGylated derivative of vitamin E, and Tetronic surfactants, pH-responsive and thermogelling polyethylene oxide (PEO)-polypropylene oxide (PPO) 4-arm block copolymers. We hypothesized that mixed micelles would form under specific conditions and provide a handle to tune formulation characteristics. Experiments: We examined the morphology of the self-assembled structures in mixtures of TPGS with two Tetronic: T1107 and T908, using a combination of dynamic light scattering (DLS), small-angle neutron scattering (SANS), NMR spectroscopy (NOESY and diffusion NMR) and oscillatory rheology, over a range of compositions, temperatures and pH. Cell viability was assessed in NIH/3T3 fibroblasts. Findings: The combination of TPGS with either of the two Tetronic produces spherical core-shell micelles that comprise both surfactants in their structure (mixed micelles). T1107 unimers incorporate into TPGS aggregates below the critical micelle temperature of the poloxamine, while mixed micelles only form under limited conditions with T908. At high concentration/temperature, small proportions of TPGS extend the gel phase, more markedly with T1107, with similar elastic moduli (30-50 kPa) and a BCC crystalline structure. Cell viability of NIH/3T3 fibroblasts grown in the hydrogels increases significantly when the poloxamine gels are doped with TPGS, making the combination of poloxamines and TPGS a promising platform for drug delivery.

Three different polysaccharides, xanthan gum, chitosan and locust bean gum, were crosslinked with or without ß-cyclodextrin, using citric acid in different ratios, to create "green" hydrogel matrices. The crosslinking of these polysaccharides was produced through an inexpensive and innocuous solvent-free synthesis process. A favorable swelling behavior of the hydrophilic matrices facilitates the sorption of the solutes tested. Interestingly, the amount of ß-cyclodextrin groups is not the only factor to yield the best sorption capability for hydrophobic model molecules: polysaccharides themselves also influence the sorption depending on their characteristic functional groups, the conformation of their chains and, as mentioned above, their degrees of swelling. In order to ascertain the effect of the polysaccharides on the sorption capabilities of a model sorbate (1-naphthol), isotherms using a wide range of solute concentrations were analyzed, and the Hill equation yielded the best fitting results and provided some insight into the mechanisms of interaction.

Device-Associated Healthcare-Associated Infections (DA-HAI) are a major threat to public health worldwide since they are associated with increased hospital stays, morbidity, mortality, financial burden, and hospital overload. A strategy to combat DA-HAI involves the use of medical devices endowed with surfaces that can kill or repel pathogens and prevent biofilm formation. We aimed to develop low-toxic protease-resistant anti-biofilm surfaces that can sensitize drug-resistant bacteria to sub-inhibitory concentrations of antibiotics. To this end, we hypothesized that polymyxin B nonapeptide (PMBN) could retain its antibiotic-enhancing potential upon immobilization on a biocompatible polymer, such as silicone. The ability of PMBN-coated silicone to sensitize a multidrug-resistant clinical isolate of Pseudomonas aeruginosa (strain Ps4) to antibiotics and block biofilm formation was assessed by viable counting, confocal microscopy and safranin uptake. These assays demonstrated that covalently immobilized PMBN enhances not only antibiotics added exogenously but also those incorporated into the functionalized coating. As a result, the functionalized surface exerted a potent bactericidal activity that precluded biofilm formation. PMBN-coated silicone displayed a high level of stability and very low cytotoxicity and hemolytic activity in the presence of antibiotics. We demonstrated for the first time that an antibiotic enhancer can retain its activity when covalently attached to a so

The combination of polymeric surfactants with different features into mixed micelles give access to properties that may be superior to the single-component micelles. In this work, we investigated synergistic effects in mixtures of D-alpha-Tocopheryl polyethylene glycol succinate (TPGS) with poloxamines (also known as Tetronic), pH-responsive and thermogelling polyethylene oxide (PEO)-polypropylene oxide (PPO) 4-arm block copolymers. We examined the morphology of the self-assembled micelles of TPGS with Tetronic 1107 (T1107) and 908 (T908) in the presence of naproxen (NA), used as a model drug, and assessed the capacity of the single and mixed micelles to trap the guest, using a combination of small-angle neutron scattering (SANS) and NMR spectroscopy (1D, 2D-NOESY and diffusion NMR), over a range of compositions and temperatures, in the dilute regime and gel state. NA did not interact with T1107 or T908 in their unimer form, but it was incorporated into the hydrophobic core of the micelles above the critical micellar temperature (CMT). In contrast, TPGS dissolved NA at any temperature, mainly in the tocopherol core, with some partitioning in the PEG-shell. The micellar structure was not altered by the presence of NA, except for an expansion of the core size, a result of the preferential accumulation of NA in that compartment. The solubility of the drug in single component micelles increased markedly with temperature, while mixed micelles produced an intermediate enhancement o

Lignocellulosic residues are a widely available energy resource, but their conversion into biogas through biomethanation may be hindered by a chemical structure with strong bonds. A strategy based on temperature-phased anaerobic digestion (TPAD) is here applied to optimize anaerobic digestion of artichoke as a representative lignocellulosic waste. The experiments consist of a first thermophilic stage conducted at 55 °C (7 and 5 days), followed by a second mesophilic stage at 35 °C. In addition, for comparison, single-stage temperature trials are carried out within the most common conditions for biomethanation (mesophilic at 35 °C, and thermophilic at 55 °C), as well as at the intermediate range (42 °C). In general, biomethanation of artichoke residues under TPAD configuration provides better performance than single-stage systems. Particularly, the best performance is observed for the TPAD arrangement using a thermophilic phase of 7 days. Thus, at this optimal configuration, volatile solids (VS) removal of 54%, and biogas and methane yields of 442 mL/g-VS and 375 mL-CH4/g-VS were reached, respectively. Moreover, a kinetic model coupling biogas generation and substrate consumption has been applied. Good agreement is found for both variables in each system tested. The calculated non-biodegradable substrate (S¿) is lower in TPAD systems (mean 49.6%) compared with that of single-stages (average 53.9%).

Polymeric materials, such as polyvinyl alcohol (PVA) and ethylene-PVA copolymers (EVOH) are widely used in the food sector as packaging materials because of their excellent properties. TiO2 nanoparticles (NPs) show photocatalytic activity; when added to the aforementioned polymers, on the one hand, they are expected to provide bactericidal capacity, whereas on the other hand, they could favor nanocomposite degradation. These types of nanoparticles can be derivatized with cyclodextrin macromolecules (CDs), which can act as food preservative carriers, increasing the packaging food protective properties. In this work, films containing beta-Cyclodextrin (beta CD)-grafted TiO2 nanoparticles and PVA or EVOH were prepared. Regarding the photocatalytic activity of the nanoparticles and the possible environmental protection, accelerated aging tests for PVA, EVOH, and their composites with cyclodextrin-grafted TiO2 nanoparticle (NP) films were performed by two methods, namely, stability chamber experiments at different conditions of temperature and relative humidity and UV light irradiation at different intensities. After analyzing the systems color changes (CIELAB) and Fourier transform infrared spectroscopy (FTIR) spectra, it was observed that the film degradation became more evident when increasing the temperature (25-80 degrees C) and relative humidity percentage (28-80%). There was no significant influence of the presence of CDs during the degradation process. When irradiating the films with UV light, the largest color variation was observed in the nanocomposite films, as expected. Moreover, the color change was more relevant with increasing NP percentages (1-5%) due to the high photocatalytic activity of TiO2. In addition, films were characterized by FTIR spectroscopy and variation in the signal intensities was observed, suggesting the increase of the material degradation in the presence of TiO2 NPs.

Several medieval tiles from Tiebas Castle in Navarre, classified as carreaux de pavement, were mineralogically analyzed. The aim was to add information to the very scarce analytical data available for carreaux de pavement in order to provide a quality primary work, mainly descriptive, in this topic. The characterization techniques applied were: optical microscopy (OM), colorimetry, Fourier transform infrared (FT-IR) spectroscopy, differential thermal analysis and thermogravimetry (DTA-TG), X-ray fluorescence (XRF) spectroscopy, petrographic microscopy (PM), X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS). The tiles comprised three layers: a top glaze with mainly silicon and lead-based compounds; a thin layer of silicoaluminate (very possibly kaolinite) called engobe under it; and the pastes, composed of quartz, hematite, potassium feldspars and calcite. Honey glazes were richer in iron, being copper-based compounds responsible for dark green glazes. The orangish-reddish color of the pastes was provided by hematite. Although the tiles were found in three different locations within the castle, no significant differences were detected among them. The carreaux de pavement from Tiebas had similarities with that from the Bordeaux region. According to the composition data and thickness of tiles from other French carreaux de pavement, the Tiebas artifacts were dated to the 13th century.

In this work, it is reported that thermal analysis techniques such as TG, DTA and X-ray thermodiffraction, performed in air or nitrogen atmosphere, are very useful for evaluating and characterizing the pigments and the supports used for the manufacture of wall paintings from the San Isidoro del Campo Monastery (fifteenth century) in which different scenes from the life of San Jeronimo are represented. The use of thermal techniques has allowed for collecting information on the technology and raw materials used in the manufacture of these wall paintings. The composition of the different colours forming the wall paintings is the following: blue by azurite, green by atacamite, red by iron oxide (hematite), cinnabar and ochre by iron oxyhydroxides (goethite), black by carbon and white by calcite. In all the colours, calcite and quartz were also identified. The paintings were performed by using the fresco technique. The support mortars are constituted of calcite, quartz and straw.

Miltefosine (MF), an alkylphospholipid originally developed for breast cancer treatment, is a highly active drug for the treatment against leishmaniasis, a neglected tropical disease considered the world's second leading cause of death by a parasitic agent after malaria. MF exhibits dose-limiting gastrointestinal side effects in patients and its penetration through lipophilic barriers is reduced. In this work we propose a reformulation of MF by incorporating the drug to poly(ethylene)oxide (PEO)-based polymeric micelles, specifically, D-alpha-tocopheryl polyethylene glycol succinate (TPGS) and Tetronic block copolymers (T904 and T1107). A full structural characterization of the aggregates has been carried out by SANS (small-angle neutron scattering) and dynamic light scattering (DLS), in combination with proton 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, to determine the precise location of the drug. The structure of MF micelles has been characterized as a function of the temperature and concentration. In the presence of the block-copolymers, MF forms mixed micelles in a wide range of temperatures, TPGS being the co-surfactant that incorporates more MF unimers. The hydrophobic tail of MF and those of the block copolymers are in close contact within the micelles, which present a core-shell structure with a hydrophilic corona formed by the PEG blocks of the TPGS and the zwitterion head group of the MF. In order to identify the best carrier, the antileishmanicidal activity of MF in the different formulations has been tested on macrophages, promastigotes and intracellular amastigotes. The combination of the three vehicles with MF makes the formulated drug more active than MF alone against L. major promastigotes, however, only the combination with T904 increases the MF activity against intracellular amastigotes. With the aim of exploring gel-based formulations of the drug, the combination of MF and T1107 under gelation conditions has also been investigated.

The mainly use of infrared spectroscopy and colorimetry allowed the characterization of the pigments and compounds of the wall paintings from the Monastery of San Isidoro del Campo in Seville, dated on the 15th century. Calcite, quartz and albite were detected in the ground mortar layers. As pigments, red ochre, yellow ochre, paratacamite, atacamite, azurite and carbon black were used, and also lime as the binder, therefore the fresco technique was employed. Both FTIR-ATR and FTIR (in transmission) experiments were performed. Comparison between materials used in some of the wall paintings from Seville in this period was performed. The article revealed important information about wall paintings within a historical context related to the 15th century Catholic Reformation.

Photocatalytic properties of titanium dioxide nanoparticles (TiO2 NPs) have encouraged their use as fillers in polymer-based nanocomposites for application in food packaging. The surface modification of TiO2 NPs with cyclodextrins (CDs) can improve their functionality in a large extent. With this purpose, sorbic acid (SA) and benzoic acid (BA), commonly used as antifungal and antibacterial food preservatives, respectively, have been encapsulated in CD-grafted NPs. Inclusion complex formation of SA and BA with a and beta CDs in water has been assessed first by means of H-1 NMR and UV-Vis spectroscopy to determine the affinity of the preservatives for the macrocycles and the stoichiometry of the complexes. The association constants of both preservatives were found to be lower for beta CD, however, the loading efficiency in beta CD-grafted NPs was higher than that exhibited by alpha CD-NPs. Release kinetics from the CD-grafted NPs have been carried out. In the case of SA, the alpha CD-grafted NPs showed a prolonged and sustained release profile, suggesting its application as microbial growth inhibition system if incorporated into packaging materials.

Gram-negative bacteria possess numerous defenses against antibiotics, due to the intrinsic permeability barrier of their outer membrane (OM), explaining the recalcitrance of some common and life-threatening infections. We report the formulation of a new drug, PPA148, which shows promising activity against all Gram-negative bacteria included in the ESKAPEE pathogens. PPA148 was solubilized by inclusion complexation with cyclodextrin followed by encapsulation in liposomes. The complex and liposomal formulation presented increased activity against E. coli compared to the pure drug when assessed with the Kirby Bauer assay. The novel formulation containing 1 mu g PPA148 reached similar efficacy levels equivalent to those of 30 mu g of pure rifampicin. A range of biophysical techniques was used to explore the mechanism of drug uptake. Langmuir trough (LT) and neutron reflectivity (NR) techniques were employed to monitor the interactions between the drug and the formulation with model membranes. We found evidence for liposome fusion with the model Gram-negative outer membrane and for cyclodextrins acting as inner membrane (IM) permeation enhancers without presenting intrinsic antimicrobial activity. An antibiotic-in-cyclodextrin-in-liposomes (ACL) formulation was developed, which targets both the bacterial OM and IM, and offers promise as a means to breach the Gram-negative cell envelope.

The incorporation of cyclodextrins into polymeric crosslinked gels of hydrophilic nature can be useful for promoting the sorption of hydrophobic molecules and/or modulating the release of active principles. The covalent addition of these excipients to the matrix integrates their solubilizing effect that can contribute to increase the capacity of retention of hydrophobic substances. In this study, three diverse polysaccharides, chitosan, xanthan gum, and locust bean gum, were crosslinked with or without beta-cyclodextrin, using citric acid in different ratios, to create hydrogel matrices. Through a green synthetic path, the efficient production of soluble and insoluble (hydrogel) networks functionalized with beta-cyclodextrin was achieved by means of a solventless procedure. The characterization of their chemical composition, swelling in water, and their sorption and release behavior were also carried out in this work.

Pseudopolyrotaxanes (PPRs) are supramolecular host-guest complexes constituted by the reversible threading of macrocycles along a polymer chain. We report the formation of hybrid PPRs (hPPRs), where two types of cyclodextrins (CDs) thread either simultaneously or sequentially on four-arm poly-(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers (Tetronic): native alpha-CD (CD) (with higher affinity for PEO) and dimethylated beta-CD (DIMEB, with higher affinity for PPO). The competitive complexation along the chains is examined with three Tetronics, differing mainly in the length of their PEO blocks: T904, T1107, and T1307. While PPRs formed with alpha-CD are insoluble, due to the hydrogen-bond network formed between adjacent alpha-CDs, the presence of DIMEB leads to soluble hybrid PPRs, slows down the kinetics of complexation, and increases the number of alpha-CDs threaded per arm. The morphology of the constructs in solution over time is followed by time-resolved small-angle neutron scattering (TR-SANS), while their crystalline structure is studied by X-ray diffraction. Whereas the complexation of the polymeric surfactant with DIMEB shifts the unimer-micelle equilibrium toward unimers, the presence of alpha-CD slows down demicellization and reduces its extent. Overall, the co-threading of two cyclodextrins on the same polymer provides a handle to tune the complexation process and the final properties of the PPR, including solubility, kinetics of complexation, and composition of the complexes.

We investigated the pH-directed self-assembly of Tetronic 304 (T304), an amphiphilic four-arm block copolymer of interest for application in drug delivery systems. While T304 and its analogues have been investigated regarding their pharmaceutical and therapeutic applications, a fundamental understanding of their pH-directed self-assembly is lacking. Integrating unbiased molecular dynamics simulations with small-angle neutron scattering and dynamic light scattering experiments provided an unprecedentedly detailed interpretation of our experimental findings and also directed the selection of suitable models for experimental data analysis. We subsequently probed the interactions that drive and hinder the self-assembly of T304 at the atomistic level of detail. pH-driven conformation changes in the central ethylenediamine group of T304, and subsequent interactions with water, ultimately drive the self-assembly of T304 and the structure of the resulting polymeric micelles. Our work provides detailed mechanistic understanding of pH-directed polymer self-assembly and supports the rational design of new pH-responsive functional polymer materials.

Interpenetrating polymer network (IPN) hydrogels were synthesised using beta-cyclodextrin (beta-CD) and N-vynil-2-pyrrolidone (NVP) crosslinked with epichlorohydrin and divinylbenzene, respectively, and prepared by four different procedures: simultaneous, sequential, hybrid and a novel one named hybrid-sequential. The IPNs prepared have been characterised by infrared spectroscopy and thermal analysis. The equilibrium swelling in water and the sorption of model substances into the IPNs have also been studied. The model sorbates (1-naphthol, 2-acetylnaphthalene and tannic acid) were selected according to the affinities towards each one of the two constituent polymers. Our studies reveal that these IPNs can be applied for the sorption of substances that can interact with the network by two mechanisms, i.e. inclusion within cyclodextrin cavities and/or via specific interactions with the functional groups present. Besides, due to the complementary character of their constituent polymers, these networks could also serve to retain two substances of different nature such as cetirizine and pseudoephedrine.

Nanocomposites based on poly(vinylidene fluoride) (PVDF) filled with barium titanate, BaTiO3, (BT) particles, and multiwalled carbon nanotubes (MWCNTs) were prepared by high-energy ball milling (HEBM) and subsequent hot pressing. This method of materials preparation allowed obtaining uniform dispersions of the nanofillers. The influence of the particles on the polymer structure and morphology was studied. To understand the origin of changes in the PVDF properties, thermal and electrical behaviors of the PVDF/BT/MWCNT nanocomposites were studied as a function of composition. The addition of BT, MWCNT, or its mixture had not any influence on the PVDF polymorphism. However, calorimetric results pointed out that the presence of the nanofillers exerted nucleation mainly ascribed to the surface to volume ratio of the nanoparticles. The capacitance of the composites increased as the nanofiller content increased, being the effect mainly dependent on the surface to volume ratio of the nanoparticles. The dielectric behavior of the materials as a function of frequency was modeled by a Debye equivalent circuit only below the percolation threshold respect to the amount of MWCNT. The piezoelectric behavior of the ternary nanocomposites was highly affected by the incorporation of the nanofillers only when high dielectric losses occurred above the percolation threshold.

Pseudo-polyrotaxanes (PPRs) are supramolecular host-guest complexes constituted by the reversible threading of a macrocycle along a polymer chain. The resuting dynamic "molecular necklaces" offer potential applications in nanotechnology, drug delivery, and biomaterials. We report the formation of PPRs by threading of cyclodextrins (CDs), cyclic oligosaccharides, onto X-shaped PEO-PPO block copolymers with two opposite presentation of their hydrophobic and hydrophilic blocks: Tetronic 904 (T904) and its reverse counterpart Tetronic 90R4 (T90R4). We assess the effects that relative block position on the polymeric surfactants and cavity size of CD have on the composition, morphology, thermodynamics, and kinetics of PPRs by using a combination of X-ray diffraction, scanning electron microscopy, NMR, UV-vis spectroscopy, and time-resolved small-angle neutron scattering (TR-SANS). Solid PPRs with lamellar microstructure and crystalline channel-like structures are obtained with native CDs and both Tetronics above a threshold concentration of the macrocycle, which varies with the type of CD and surfactant. While gamma-CD can form PPRs with both Tetronics, alpha-CD only forms a PPR with T90R4 at high concentrations. The results can be explained in terms of the preferential complexation of alpha-CD with EO and gamma-CD with PO monomers, which also has a direct impact on the kinetics of PPR formation.

An original family of multivalent vectors encompassing gemini and facial amphiphilicity, namely cationic Siamese twin surfactants, has been prepared fromthe disaccharide trehalose; molecular engineering lets us modulate the self-assembling properties and the topology of the nanocomplexes with plasmid DNA for efficient gene delivery in vitro and in vivo.

The solubilisation of methylparaben (MP), an antimicrobial agent used as a food preservative and in cosmetics and personal-care products, in two poloxamines of different Hydrophilic-Lipophilic Balance (HLB), namely Tetronic 904 (T904) and 1107 (T1107), has been studied. The influence of the preservative on the aggregation behaviour of both Tetronics has been analysed by dynamic light scattering (DLS) and small-angle neutron scattering (SANS), while the precise location of the molecule in the aggregates as well as the effects of the micellar solubilisation on the reactivity of the preservative have been elucidated by NMR and UV spectroscopies. The presence of MP reduces the critical micelle temperature (CMT) of any of the poloxamines and induces the formation of larger micelles at room temperature compared to the plain poloxamines; in addition, a remarkable temperature dependent effect on the structure of the micelles has been detected, which progressively evolve from core-shell spheres to rods as the temperature increases. The incorporation of the preservative into the micelles modifies its reactivity against alkaline hydrolysis, resulting in a decrease of its reaction rate constant in which the dominant factor for the reduction in the hydrolysis rate is the incorporation into the micelle core, with a little effect of the length of the hydrophilic polyethylene oxide (PEO) blocks.

Low density polyethylene ( LDPE) based nanocomposites containing multi-walled carbon nanotubes ( MWCNTs) were prepared by a two-stepprocess consisting of apre-mixture using high energy ball milling ( HEBM) and subsequent hotpressing. The effects of ball milling and the presence of the MWCNTs on some physical properties of the materials and the antimicrobial efficiency against DH5.. Escherichia coli were studied. Fourier transform infrared spectroscopy revealed that the polymer structure did not change in the final materials after the addition of MWCNTs and mixing. Differential scanning calorimetry showed small differences in the LDPEthermal behavior as a function of the type ofmaterial due to small changes in the polymer crystallization. This result was mainly ascribed to the milling process rather than to the incorporation of the MWCNTs. The presence of 1% by weight of the nanofiller increased the rigidity and hydrophobicity of the nanocomposites with respect to neat LDPE. This effect was explained by the preferential location of theMWCNTs in the surface of the material as themain factor decreasing the polar contribution to the surface free energy. A correlation between hydrophobicity, biofilm development and the shape and size of DH5.. E. coli was observed, indicating that the presence of MWCNTs leads to a biocide effect by decreasing cell adhesion and changing itsmetabolism.

Fibers of poly(vinylidene fluoride) (PVDF) filled with multiwalled carbon nanotubes (MWCNTs) were prepared by solution blow spinning (SBS). The influence of the MWCNTs on the surface morphology and mechanical behavior of single fibers was studied. The morphology of the materials prepared and the dispersion of the MWCNTs within the polymer were studied by optical microscopy (OM) and transmission electron microscopy (TEM), while atomic force microscopy (AFM) was used to inspect the topography of single fibers and to perform nanoindentation tests. OM and TEM images indicated a good dispersion of the MWCNTs within the PVDF. AFM images evidenced clear changes in the topography of the blow-spun fibers when the MWCNTs were present in the polymer. A greater amount of MWCNTs in the PVDF led to more heterogeneous fiber surfaces. The nanoindentation force curves revealed that the stiffness was practically constant along the fibers, which indicated that the mechanical response was homogeneous and, in turn, an even distribution of the MWCNTs. The incorporation of the MWCNTs produced a mechanical reinforcement of the PVDF fibers, showing increases of 31% and 49% in the elastic modulus when 1% and 5% by weight of MWCNTs were added to the polymer, respectively.

In this paper, the use of techniques such as TGA, FTIR-ATR and XRD has provided valuable information about the lignocellulosic wastes in anaerobic digestion (AD) processes. A deep study of their break-down in solid state could improve the management of these recalcitrant substrates. Representative wastes (artichoke -ART-, asparagus -ASP-, the co-digestion of both -AcoD-and pure cellulose -CELL-) were assessed in batch. The main obtained results were related to biochemical parameters. As the biomethanization progressed, hemicellulose, cellulose and lignin were weakened as shown by TGA, and cellulose crystallinity decreased as demonstrated by XRD. Additionally, results from FTIR-ATR allowed hypothesizing that the formation of acetate in solid state did not always lead to its solubilisation, thus hindering biogas formation. AcoD and CELL were the most successful in releasing the newly formed acetate from the solid fraction to the aqueous medium, increasing its bioavailability, which was supported by the higher biogas production.

This paper examines the long-term application of a cyclodextrin hydrogel sorbent in multiple sorption-desorption cycles. Aqueous phenol was the target pollutant, whilst methanol, ethanol and isopropanol were chosen as eluents. The experimental results were well described by empirical models: the breakthrough curves by a two-parameter dose-response equation, and the elution curves by a pulse peak equation with two independent parameters. The differences in polarity of solvents produced sorbent fragmentation, particularly marked for isopropanol and considerably lower for methanol, and therefore a progressive increase in mass-transfer coefficients. In addition, a dual approach was developed from the proposed breakthrough model to address the mass transport of sorbate within the packed beds. The first one defines an average mass-transfer coefficient as representative for each complete sorption cycle, whereas a time-profile of this coefficient is deduced in the second method. A sorption capacity of 29.6 mg-phenol/g-sorbent was found in the working conditions.

The degradation processes that occurred on metal threads applied in the embroidery used for clothing and in the ornamentation of sculptures, the Sevillian Holy Week processions, and Portuguese and Spanish palace and museum are thoroughly analyzed. Some threads from the 14th and 18-19th centuries were considered. In the metal threads, sulphur- and chlorine-based compounds were detected either individually or together, depending on the degradation process. Basic silver carbonate, sodium bicarbonate and copper-based compounds were also observed. The different degradation processes were attributed to different factors, such as environmental contamination, degradation of the fibrous cores, and inadequate cleaning and/or mechanical treatments. (C) 2018 Elsevier Masson SAS. All rights reserved.

This work comprises an exhaustive study of Spanish decorative leathers dating from the 12th to 14th centuries. These paintings are considered a key example of a crucible of artistic styles: Gothic, Islamic and Florentine Trecento. The goal of this work was to use the scientific information provided by a number of experimental techniques - namely EDX, micro-FTIR, micro-Raman and micro-XRD - to assess the dating of the wooden vault, leather preparation and filling fibres. Another goal was to assess the artistic technique based on the characterization of pigments and the differentiation between original materials and those added throughout its history. Gypsum was the original preparation layer extended over the leather. A new preparation stratum was added in further interventions with the artwork. The original pictorial materials and those used during refurbishments have been identified. Original pigments were: red lead, Mars red, red lake, cinnabar, lapis lazuli, red ochres, raw sienna, white lead and charcoal black. Gilding was also found. Pigments added during restoration were: barite, emerald green, rutile, anatase, Mars red, cadmium red, lithopone, cadmium yellow, charcoal black and orpiment.

This work explores the behavior of a fluidized-bed bioreactor, packed with a hydrogel carrier of cyclodextrin-based polymer, under transient shock-loading events to evaluate its robustness and stability. Fourteen input rectangular pulses with different steps (6-24 times the baseline concentration) and duration (0.5-8 times the hydraulic residence time) were applied and the dynamic responses measured. A new shock-loading index is defined to quantify the combined effect of the influent concentration increase and the perturbation duration. The shock-loading index is directly proportional to the extra amount of phenol removed, to the additional oxygen consumed in the shock pulse, and to the time to return to baseline conditions. A simple model was developed to predict the effluent phenol concentration under pulsed shock-loading events. It assumes that a continuous-flow complete-mix system without diffusional mass transfer resistance in the biofilm. In addition, substrate adsorption is modeled using a simple concept based on the constant-pattern theory, while substrate biodegradation is described by the Haldane model. In spite of its conceptual simplicity, the model provides a pragmatic approach predicting a good match for data obtained during overload events (R-2 = 0.9810). The best-fitting parameters obtained were mu(M) = 0.166 +/- 0.007 d(-1), K-S = 8.62 +/- 0.46 mg/L, and K-I = 95.3 +/- 3.8 mg/L.

Microbial dynamics in an upgrading biogas reactor system undergoing a more than two years-period at stable operating conditions were explored. The carbon dioxide generated during biomass degradation in the first reactor of the system was converted to methane into the secondary reactor by addition of external hydrogen. Considering the overall efficiency, the long-term operation period resulted in an improved biogas upgrading performance (99% methane content). However, a remarkable accumulation of acetate was revealed, indicating the enhancement of homoacetogenic activity. For this reason, a shift in the anaerobic digestion microbiome was expected and evaluated by 16S rRNA amplicon analysis. Results demonstrated that the most abundant archaeal species identified in the first time point, Candidatus Methanoculleus thermohydrogenotrophicum, was replaced by Methanothermobacter thermautotrophicus, becoming dominant after the community adaptation. The most interesting taxonomic units were clustered by relative abundance and six main long-term adaptation trends were found, characterizing functionally related microbes (e.g. homoacetogens).

The majority of the studied artworks were altarpieces, sculptures and/or wood-based works from different periods. Non-traditional gilding techniques have been first described in this paper, such as those that employ materials as oil in the gilding on bole, glue and bole with lead white in mordant gilding, vermilion in the preparation layers; and brass gilding or those with aluminium, lead chromate, mica or corla trying to imitate the golden hue in restoration or repaint processes. For the determination of the composition of the different gilded layers, spectroscopic techniques, such as FTIR and micro-Raman, and SEM-EDX elemental chemical analyses were successfully used. (C) 2017 Elsevier Masson SAS. All rights reserved.

Basalt fibers were surface treated with silane coupling agents as a method to enhance the adhesion and durability of fiber-matrix interfaces in concrete based composite materials. In particular, this work has been focused on the study of basalt fibers chemical coatings with aminosilanes and their subsequent characterization. Surface treatments were carried out after removing the original sizing applied by manufacturer and pretreating them with an activation process of surface silanol regeneration. Different samples were considered to make convenient comparisons: as received fibers (commercial), calcinated fibers (without commercial sizing), activated samples (calcinated fibers subjected to an acid process for hydroxyl regeneration), and silanized fibers with ¿-aminopropiltriethoxysilane, ¿-aminopropilmethyldiethoxysilane and a mixture of 50% by weight of both silanes. A deep characterization was carried out in terms of structure using X-ray diffraction, XRD, and Fourier transform infrared spectroscopy, FTIR, thermal properties by thermogravimetric analysis, TGA, coupled with single differential thermal analysis, SDTA, and morphology by scanning electron microscopy, SEM, and atomic force microscopy, AFM.

Poly(methyl methacrylate) (PMMA) films filled with titanium oxide (TiO2) nanoparticles were prepared by solution blow spinning (SBS). The influence of the presence of nanoparticles (up to 10% by weight) in the physicochemical properties of the material was studied, focusing on the morphology, structure, and thermal properties, by scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), thermogravimetry (TGA), and differential scanning calorimetry (DSC). It was demonstrated that SBS allows obtaining PMMA/TiO2 nanocomposites with a relatively high amount of nanoparticles uniformly dispersed within the polymeric matrix, varying the surface characteristics of the films according to the amount of TiO2. The results indicate that the flow of the macromolecules is somewhat forced by the SBS process, and that specific interactions between the ester group of the MMA and the surface of the nanoparticles induce a preferential conformation of the functional group with respect to the PMMA backbone, at least at low loads of nanopartciles, conditions in which the self-aggregation of the nanofiller takes place in a lesser extent.

The freezing-thawing is an advantageous method to produce hydrogels without crosslinking agents. In this study chitosan-poly(vinyl alcohol) (CS-PVA) hydrogels were prepared by varying the freezing conditions and composition, which affect the final characteristics of the products. The swelling degree, morphology, porosity, and diflunisal drug loading, as well as the drug release profiles were evaluated. The hydrogel swelling ratio was found to be mainly affected by the CS content, the number of freezing cycles and the temperature. SEM micrographs and porosity data confirm that pore size increases with the chitosan content. However, the use of either lower temperatures or longer freezing times, results in higher porosity and smaller pores. The drug release times of the CS-PVA hydrogels were as long as 30 h, and according to the mathematical fitting, a simple diffusion mechanism dominates the process. Moreover, a mathematical model predicting the hydrogels physical and structural behavior is proposed.

In this work, the antimicrobial effect of silver nanoparticles in polyethylene based nanocomposites has been investigated using a non-conventional processing method to produce homogeneous materials. High energy ball milling under cryogenic conditions was used to achieve a powder of well-blended low-density polyethylene and commercial silver nanoparticles. The final composites in the form of films were obtained by hot pressing. The effect of various silver nanoparticles content (0, 0.5, 1 and 2 wt %) on the properties of low-density polyethylene and the antimicrobial effectiveness of the composite against DH5 ff Escherichia coli were studied. The presence of silver nanoparticles did not seem to affect the surface energy and thermal properties of the materials. Apart from the inhibition of bacterial growth, slight changes in the aspect ratio of the bacteria with the content of particles were observed, suggesting a direct relationship between the presence of silver nanoparticles and the proliferation of DH5 alpha ff E. coli (Escherichia coli) cells. Results indicate that these materials may be used to commercially produce antimicrobial polymers with potential applications in the food and health industries.