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In this study, two packaging materials, modified polypropylene (MPP) and polyethylene terephthalate/aluminum/ low-density polyethylene (PETFA-Al-LDPE) were studied under various atmospheric conditions: 100% CO2, 70% N2 - 30% CO2, 80% N2 - 20% CO2 for packing probiotic ultrafiltered (UF) white brined cheese. pH, titratable acidity, moisture content, Lacticaseibacillus paracasei viability and overall acceptability were monitored within a 12-week period. The control samples were packaged in atmospheric air. Results revealed that samples packaged in PETFA-Al-LDPE with the combination of 70% N2 - 30% CO2 had the lowest pH, highest acidity and moisture content. The viability of Lacticaseibacillus paracasei was reported to be 4*106 CFU/g within 12 weeks. The highest and lowest overall acceptability was for the cheese packaged in 70% N2 - 30% CO2 and the control sample, respectively., U ovom istraživanju je ispitivana mogućnost primjene dvaju ambalažnih materijala - modificiranog polipropilena (MPP) i polietilen tereftalata/aluminij/polietilen niske gustoće (PETFA-Al-LDPE) u različitim uvjetima modificirane atmosfere (100 % CO2, 70 % N2 – 30 % CO2, 80 % N2 - 20 % CO2) za pakiranje probiotičkog sira iz salamure proizvedenog iz ultrafiltriranog (UF) mlijeka. Tijekom 12 tjedana čuvanja uzorcima sira su određivani pH, titracijska kiselost, sadržaj vlage, preživljavanje soja Lacticaseibacillus paracasei i prihvatljivost. Kontrolni uzorci su pakirani u normalnoj atmosferi (zrak). Dobiveni rezutati ukazuju kako uzorci pakirani u PETFA-Al-LDPE i modificiranoj atmosferi 70 % N2 - 30 % CO2 imaju najniži pH, te najveću kiselost i sadržaj vlage. Preživljavanje soja Lacticaseibacillus paracasei je bilo oko 4x106 CFU/g tijekom 12 tjedana. Najnižu i najvišu prihvatljivost su imali uzorak pakiran u atmosferi 70% N2 - 30 % CO2 te kontrolni uzorak.

Prostate cancer (PCa) is a slow-growing neoplasm that has, when diagnosed in its early stages, great chances of cure. During initial tumor development, current diagnostic methods fail to have the desired accuracy, thus, it is necessary to develop or improve current detection methods and prognostic markers for PCa. In this scenario, films composed of hyaluronic acid (HA) and chitosan (CHI) have demonstrated significant capture potential of prostate tumor cells (PC3 line), exploring HA as a CD44 receptor ligand and direct mediator in cell-film adhesion. Here, we present a strategy to control structural and cell adhesion properties of HA/CHI films based on film assembly conditions. Films were built via Layer-by-layer (LbL) deposition, where the pH conditions (3.0 and 5.0) and number of bilayers (3.5, 10.5, and 20.5) were controlled. The characterization of these films was carried out using profilometry, ultraviolet-visible (UV-VIS), atomic force microscopy (AFM) and contact angle measurements. Multilayer HA/CHI films produced at pH 3.0 gave optimum surface wettability and availability of free carboxyl groups. In turn, at pH 5.0, the coverings were thinner and presented a smoother surface. Films prepared with 3.5 bilayers showed greater tumor cell capture regardless of the pH condition, while films containing 10.5 and 20.5 bilayers presented a significant swelling process, which compromised their cell adhesion potential. This study shows that surface chemistry and morphology are critical factors for the development of biomaterials designed for several cell adhesion applications, such as rapid diagnostic, cell signaling, and biosensing mechanisms.

Non-viral vectors represent versatile and immunologically safer alternatives for nucleic acid delivery. Nanoneedles and high-aspect ratio nanostructures are unconventional but interesting delivery systems, in which delivery is mediated by surface interactions. Herein, nanoneedles are synergistically combined with polysaccharide-polyplex nanofilms and enhanced transfection efficiency is observed, compared to polyplexes in suspension. Different polyplex-polyelectrolyte nanofilm combinations are assessed and it is found that transfection efficiency is enhanced when using polysaccharide-based polyanions, rather than being only specific for hyaluronic acid, as suggested in earlier studies. Moreover, results show that enhanced transfection is not mediated by interactions with the CD44 receptor, previously hypothesized as a major mechanism mediating enhancement via hyaluronate. In cardiac tissue, nanoneedles are shown to increase the transfection efficiency of nanofilms compared to flat substrates; while in vitro, high transfection efficiencies are observed in nanostructures where cells present large interfacing areas with the substrate. The results of this study demonstrate that surface-mediated transfection using this system is efficient and safe, requiring amounts of nucleic acid with an order of magnitude lower than standard culture transfection. These findings expand the spectrum of possible polyelectrolyte combinations that can be used for the development of suitable non-viral vectors for exploration in further clinical trials.

Multilayer films with high-density layer interfaces have been studied widely because of the unique mechanical and functional properties. Magnetron sputtering is widely chosen to fabricate multilayer films because of the convenience in controlling the microstructure. Essentially, the properties of multilayer films are decided by the microstructure, which could be adjusted by manipulating the deposition parameters, such as deposition temperature, rate, bias, and target–substrate distance, during the sputter process. In this review, the influences of the deposition parameters on the microstructure evolution of the multilayer films have been summarized. Additionally, the impacts of individual layer thickness on the microstructure evolution as well as the irradiation behavior of various multilayer films have been discussed.

Ferroelectric multilayer films attract great attention for a wide variation of applications. The synergistic effect by combining different functional layers induces distinctive electrical properties. In this study, ferroelectric BaZr0.2Ti0.8O3/PbZr0.52Ti0.48O3/BaZr0.2Ti0.8O3 (BZT/PZT/BZT) multilayer thin films are designed and fabricated by using the magnetron sputtering method, and a LaNiO3 (LNO) seed layer is introduced. The microstructures and electrical properties of the BZT/PZT/BZT films with and without the LNO seed layer are systematically studied. The results show that the BZT/PZT/BZT/LNO thin film exhibits much lower surface roughness and a preferred (100)-orientation growth, with the growth template and tensile stress provided by the LNO layer. Moreover, an enhanced dielectric constant, decreased dielectric loss, and improved ferroelectric properties are achieved in BZT/PZT/BZT/LNO thin films. This work reveals that the seed layer can play an important role in improving the microstructure and properties of ferroelectric multilayer films.

The spontaneously self-organizing multilayered graphite-like carbon (denoted as GLC) /TiC films with various bilayer periods in the range of 13.3–17.5 nm were deposited on silicon and 1Cr18Mn8Ni5N stainless steel substrates using closed field magnetron sputtering deposition facility. The microstructures and chemical compositions of the prepared multilayered films were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy respectively. The self-organizing multilayered structures in all of the films consisted of titanium carbide layers and sp2-rich carbon layers periodically alternate arrangement. The TiC contents and bilayer periods of the multilayered films can be controlled by means of adjusting of sputtering current of graphite target. Furthermore, the mechanical and tribological performances of the prepared films were appraised by nano-indentor, scratch measures, and ball-on-plate tribometer respectively. The results indicated that multilayer structure endowed the as-deposited TiC/GLC films outstanding mechanical and tribological properties, especially the multilayer film with 15.9 nm bilayer period deposited at 10 A sputtering current showed the excellent adhesion strength and hardness, Simultaneously it also exhibited the lowest average friction coefficient in the humid environment owing to its high content of sp2 hybrid carbon.

Introduction. An incomplete list of graphene properties includes high electric conductivity, thermal conductivity, strength, large surface area, high light transmittance. Graphene is a very promising material from the point of view of its application in micro- and nanoelectronics. In addition, graphene advantage is a possibility of its obtaining by various ways. It allows creating materials with desired physicochemical properties by using appropriate technological methods. Objective. The investigation of a thermal reduction temperature influence on physicochemical properties of graphene oxide (GO) films. Materials and methods. In the present work, GO films are obtained on a slide surface by its immersing and removing from a graphene oxide water dispersion (dip coating). Obtained samples are studied by methods of scanning electron microscopy, Raman spectroscopy, and elemental CHN analysis. A sheet resistance is measured by a four-point probes method. Results. A content difference of elements (C, H, N) in studied samples, and both graphene structure defectiveness and sheet resistance decrease, are found to be proportional to a reduction temperature increase. A GO films thickness decrease during a heat treatment is also observed, which is presumably associated with a functional GO groups loss while thermal reduction. Conclusion. Research results demonstrate a possibility of a carbon films with desired physicochemical properties obtaining from a reduced graphene oxide (RGO), which can be used in thin-film technologies. Presented materials can also be useful in issues related to GO and RGO obtaining and applying.

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Multilayer thin films polymer have been commonly used in a wide range of electronics applications, such as solar cells, photoconductors, semiconductors, and light-emitting diodes, in which failure due to delamination can occur. For evaluating and improving the quality of a multilayer thin-film product, the interfacial strength between its layers must be measured correctly and accurately. In this work, the interfacial strength of a multilayer thin-film polymer was quantified by measuring the interfacial energy release rate (interfacial fracture toughness), Gi , using the nanoindentation test technique. Three specimens of four-layer thin films were fabricated on a glass substrate. The top layer of each specimen was prepared with different thicknesses. The unloading curve technique introduced by Kozuki and Kishimoto (2010) was implemented to quantify the Gi of each specimen. Then, cross-sectional observation of the specimens was performed to confirm the layer thicknesses and to identify the delamination condition after the test. The measured Gi tended to increase as the range between the two unloading curves used to calculate the delamination energy widened. This phenomenon is believed to be caused by the plastic energy of the deformed films during the indentation process. Finally, an empirical method for eliminating the effect of the plastic energy on the measured Gi was proposed. Using this method, a pure Gi value can be effectively extracted; thus, the interfacial strength of multilayer thin-film polymers can be measured correctly and accurately.

In this study, we report the isolation of cellulose nanocrystals (CNCs) from Isora plant fibers by sulfuric acid hydrolysis and their assembly on hydrophilic cellulose and silicon-di-oxide (SiO2) surfaces via a layer-by-layer (LBL) deposition method. The isolated CNCs were monodis-persed and exhibited a length of 200-300 nm and a diameter of 10-20 nm, a negative zetapotential (34-39 mV) over a wide pH range, and high stability in water at various concentrations. The multi-layered structure, adsorbed mass, conformational changes, and anticoagulant activity of sequen-tially deposited anionic (sulfated) CNCs and cationic polyethyleneimine (PEI) on the surfaces of cellulose and SiO2 by LBL deposition were investigated using a quartz crystal microbalance tech-nique. The organization and surface features (i.e., morphology, thickness, wettability) of CNCs ad-sorbed on the surfaces of PEI deposited at different ionic strengths (50-300 mM) of sodium chloride were analysed in detail by profilometry layer-thickness, atomic force microscopy and contact angle measurements. Compared to cellulose (control sample), the total coagulation time and plasma deposition were increased and decreased, respectively, for multilayers of PEI/CNCs. This study should provide new possibilities to fabricate and tailor the physicochemical properties of multilayer films from polysaccharide-based nanocrystals for various biomedical applications. Acknowledgments: The authors acknowledge Volker Ribitsch (retired) from the University of Graz/Austria for his support and valuable discussion for this manuscript. The authors also acknowledge the financial support from the Slovenian National Research Agency ARRS (Grant No. J4-1764). Scopus

Xingfang Yu,1,* Xin Liao,2,* Hongwei Chen1 1Department of Orthopedics, The Affiliated Yiwu Hospital of Wenzhou Medical University, Yiwu, Zhejiang, 322000, People’s Republic of China; 2Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hongwei ChenDepartment of Orthopedics, The Affiliated Yiwu Hospital of Wenzhou Medical University, Yiwu, Zhejiang, 322000, People’s Republic of ChinaTel +86-13506896988Email sssaaa18@163.comBackground: Bone infections remain one of the most common and serious complications of orthopedic surgery, posing a tremendous economic burden to society and patients. This is because bacteria colonize and multiply on the surface of the implant. The (MMT/PLL)8 multilayer films have been shown to effectively release antibiotics depending on the changes in the microenvironment. Here, vancomycin was loaded into the (MMT/PLL)8 multilayer films, which were prepared to be used as a local delivery system for the treatment of bone infections.Methods: We used the layer-by-layer self-assembly method to prepare VA-loaded coatings (MMT/PLL-VA)8 consisting of montmorillonite (MMT), poly-L-lysine (PLL), and VA. The thickness and surface morphology of coatings were characterized using spectroscopic ellipsometry and scanning electron microscopy (SEM). In order to evaluate the drug release behavior from coatings in different media, we measured the size of the zone of inhibition. Additionally, in vitro antibacterial activity was assessed using the shake-flask culture method and SEM images, while that of in vivo was evaluated by establishing an animal model of bone infection.Results: Our findings revealed that small-molecule antibiotics were successfully loaded into the (MMT/PLL-VA)8 multilayer film structure during the hierarchical self-assembly process and subsequently the multilayer film structure depicted linear growth behavior. The PLL in the multilayer films was progressively degraded which triggered the VA release when contacted with CMS or bacterial infections. The release of VA from multilayer film structure depends on the concentration changes of CMS. Notably, the multilayer films presented great in vitro cell compatibility. Moreover, the prepared antibacterial multilayer films showed excellent antibacterial property by killing more than 99.99% of S. aureus in 24 h. More importantly, we found that multilayer film exhibits good sterilization effect and biocompatibility under the stimulation of bacterial liquid both in vitro and in vivo antibacterial ability tests.Conclusion: Altogether, this study shows that (MMT/PLL-VA)8 multilayer films containing CMS and bacteria-responsive drug release properties posess high bactericidal activity and good biocompatibility. This finding provides a novel strategy for the treatment of bone infections.Keywords: bone infections, multilayer films, microenvironment, layer-by-layer, antibacterial

Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate.

An understanding of the structural evolution in micro-/nano-layer co-extrusion process is essential to fabricate high-performance multilayered products. Therefore, in this work, we reveal systematically the multiscale structural development, involving both the layer architecture and microstructure within layers of micro-/nano-layer coextruded polymer films, as well as its relationship to dielectric properties, based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/polycarbonate (PC) system. Interestingly, layer architecture and morphology show strong dependences on the nominal layer thicknesses. Particularly, with layer thickness reduced to nanometer scale, interfacial instabilities triggered by viscoelastic differences between components emerge with the creation of micro-droplets and micro-sheets. Films show an enhanced crystallization with the formation of two-dimensional (2D) spherulites in microlayer coextruded systems and the oriented in-plane lamellae in nanolayer coextruded counterparts, where layer breakup in the thinner layers further changes the crystallization behaviors. These macro- and microscopic structures, developed from the co-extrusion process, substantially influence the dielectric properties of coextruded films. Mechanism responsible for dielectric performance is further proposed by considering these effects of multiscale structure on the dipole switching and charge hopping in the multilayered structures. This work clearly demonstrates how the multiscale structural evolution during the micro-/nano-layer coextrusion process can control the dielectric properties of multilayered products.

In this work, we prepared TiO2 and Co multilayer thin films via DC magnetron sputtering method on (100) GaAs and (100) Si substrates. The power for each target (TiO2 and Co), deposition time of the layers, and pressure during deposition were kept constant. From XRD, Raman, and IR measurements, the formation of the rutile and triclinic Co phases were identified in the multilayer thin films. An annealing process was carried in situ on all samples and subsequent to the deposition stage during 2 h. The substrate used was GaAs and Si wafer, favoring the formation and growth of the found phases. The diffusion and interdiffusion of the layers in the thin films were determined from Rutherford Backscattering Spectroscopy (RBS). In particular, Co and Ga were observed to associate after the annealing process according to the depth profiles. Due to the interdiffusion layers, the parallel magnetic contribution is not significant in the bilayer. Curves I-V of the Co/TiO2 bilayer showed the presence of resistive switching, according to the bipolar resistive. A correlation between synthesis parameters and the physical properties of the multilayers is presented, The Universidad Nacional de Colombia, COLCIENCIAS Conv. 727- 2015 and Universidad del Rosario supported this work. Heiddy Paola Quiroz is scholarship PhD of Doctorados COLCIENCIAS. Acknowledgments to the Universidad del Rosario for the EDI 2017 scholarship to professor Fredy Mesa

Electromagnetic interference (EMI), an unwanted phenomenon, often affects the reliability of precise electronic circuitry. To prevent this, an effective shielding is prerequisite to protect the electronic devices. In this study, an attempt was made to understand how processing of polymeric blend nanocomposites involving multiwalled carbon nanotubes (MWCNTs) affects the evolving interconnected network structure of MWCNTs and eventually their EMI shielding properties. Thereby, the overall blend morphology and especially the connectivity of the polycarbonate (PC) component, in which the MWCNTs tend to migrate, as well as the perfectness of their migration, and the state of nanotube dispersion are considered. For this purpose, blends of varying composition of PC and poly(methyl methacrylate) were chosen as a model system as they show a phase diagram with lower critical solution temperature type of characteristic. Such blends were processed in two different ways: solution mixing (from the homogeneous state) and melt mixing (in the biphasic state). In both the processes, MWCNTs (3 wt %) were mixed into the blends, and the evolved structures (after phase separation induced by annealing in solution-mixed blends) and the quenched structures (as the blends exit the extruder) were systematically studied using transmission electron microscopy (TEM). Both the set of blends were subjected to the same thermal history, however, under different conditions such as under quiescent conditions (in the case of solution mixing) and under shear (in the case of melt mixing). The electrical volume conductivity and the evolved morphologies of these blend nanocomposites were evaluated and correlated with the measured EMI shielding behavior. The results indicated that irrespective of the type of processing, the MWCNTs localized in the PC component; driven by thermodynamic factors and depending on the blend composition, sea-island, cocontinuous, and phase-inverted structures evolved. Interestingly, the better interconnected network structures of MWCNTs observed using TEM in the solution-mixed samples together with larger nanotube lengths resulted in higher EMI shielding properties (-27 dB at 18 GHz) even if slightly higher electrical volume conductivities were observed in melt-mixed samples. Moreover, the shielding was absorption-driven, facilitated by the dense network of MWCNTs in the PC component of the blends, at any given concentration of nanotubes. Taken together, this study highlights the effects of different blend nanocomposite preparation methods (solution and melt) and the developed morphology and nanotube network structure in MWCNT filled blend nanocomposites on the EMI shielding behavior.

Encapsulation of cells has been an active area of research. Among various methods for encapsulation, Layer-by-Layer (LbL) offers extensive flexibility in the design of surfaces and their interfacial nanoarchitectonics. A diverse range of functionalities have been recently demonstrated for cell encapsulation including protection and improved circulation. Here, we present a new strategy of cell encapsulation in a hybrid coating containing LbL assembly functionalized with gold nanoparticle aggregates. The effect of this hybrid coating on cell viability was assessed. Subsequently, upon laser illumination the encapsulated cells undergo immediate necrosis caused by the localized heat generated by the laser beam on gold nanoparticle aggregates. Similarly to affecting polyelectrolyte multilayer capsules, one envisions controlling surface properties of cells remotely by a laser beam. Further applications of the proposed approach are expected to be in biomedicine.

Self-defensive antibiotic-loaded coatings have shown promise in inhibiting growth of pathogenic bacteria adhering to biomaterial implants and devices, but direct proof that their antibacterial release is triggered by bacterially-induced acidification of the immediate environment under buffered conditions remained elusive. Here, we demonstrate that Staphylococcus aureus and Escherichia coli adhering to such coatings generate highly localized acidification, even in buffered conditions, to activate pH-triggered, self-defensive antibiotic release. To this end, we utilized chemically crosslinked layer-by-layer hydrogel coatings of poly(methacrylic acid) with a covalently attached pH-sensitive SNARF-1 fluorescent label for imaging, and unlabeled-antibiotic (gentamicin or polymyxin B) loaded coatings for antibacterial studies. Local acidification of the coatings induced by S. aureus and E. coli adhering to the coatings was demonstrated by confocal-laser-scanning-microscopy via wavelength-resolved imaging. pH-triggered antibiotic release under static, small volume conditions yielded high bacterial killing efficiencies for S. aureus and E. coli . Gentamicin-loaded films retained their antibacterial activity against S. aureus under fluid flow in buffered conditions. Antibacterial activity increased with the number of polymer layers in the films. Altogether, pH-triggered, self-defensive antibiotic-loaded coatings become activated by highly localized acidification in the immediate environment of an adhering bacterium, offering potential for clinical application with minimized side-effects. Statement of significance Polymeric coatings were created that are able to uptake and selectively release antibiotics upon stimulus by adhering bacteria in order to understand the fundamental mechanisms behind pH-triggered antibiotic release as a potential way to prevent biomaterial-associated infections. Through fluorescent imaging studies, this work importantly shows that adhering bacteria produce highly localized pH changes even in buffer. Accordingly such coatings only demonstrate antibacterial activity by antibiotic release in the presence of adhering bacteria. This is clinically important, because ad libitum releasing antibiotic coatings usually show a burst release and have often lost their antibiotic content when bacteria adhere.

Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to “Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging” by Garofalo et al. (2017) [1] . Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2] , [3] , [4] . The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

We demonstrate a method for the formation of multilayers composed of reduced graphene oxide (rGO), which can be used for transparent, conducting thin films. Using the layer-by-layer (LbL) assembly of positively and negatively charged GO sheets, we could obtain thin films with highly controllable sheet resistance. The natural negative charge of graphene oxide was turned to positive by the amidation reaction. After forming the multilayer films, the graphene oxide underwent thermal reduction at temperatures above 150 °C. The (rGO+/rGO−) films were characterized by UV-Vis and scanning electron microscopy (SEM), and their conductivity was measured by the four-point method. We found that after deposition of five (rGO+/rGO−), the coating structure reached the percolation limit, and the film resistance decreased more gradually to around 20 kΩ/sq for the films obtained by eleven deposition cycles with graphene oxide reduced at 250 °C. The formation of thin films on polyimide allows the forming of new flexible conductive materials, which can find applications, e.g., in biomedicine as new electroactive, low-cost, disposable sensors.

The direct local delivery of short interfering RNA (siRNA) to tissues may present solutions to several complex medical conditions. In particular, chronic wound healing is a serious and painful complication of diabetes mellitus (DM) affecting as many as one in four patients with a three year recurrence rate of more than 50% and leaving over 70,000 patients in the United States alone facing amputation. Here we describe the use of siRNA delivered locally into the diabetic ulcer directly and in a sustained fashion to knockdown a chronically upregulated extracellular matrix protease, matrix metalloproteinase-9 (MMP-9), to improve wound healing. A self-assembled polymer thin film coating, when applied conformally to commercially available nylon bandages, sustains the delivery of small interfering RNA (siRNA) into the wound bed while maintaining activity and facilitating transfection. This approach reduces protein expression and enzyme activity within the wound for over two weeks, leading to a significant improvement in chronic wound healing.

International audience; The work is dedicated to the investigation of blister formation in ZrN/SiNx multilayer films irradiated with He ions (30 keV) and annealed in a vacuum at 600 °C. Multilayer films were prepared by reactive magnetron sputter-deposition on Si wafers under Ar + N2 plasma discharges. ZrN/SiNx films were deposited by sequential sputtering from elemental Zr and Si3N4 targets at substrate temperature of 300 °C, with ZrN and SiNx layer thickness varying from 2 to 10 nm. According to transmission electron microscopy (TEM), the multilayer films consist of nanocrystalline (002)-oriented ZrN and amorphous SiNx layers. Surface morphology changes of ZrN/SiNx films irradiated with He ions (30 keV) and annealed in a vacuum at 600 °C were studied by scanning electron (SEM) and atomic-force microscopy (AFM) methods. It has been found that under He ions (30 keV) irradiation ZrN/SiNx multilayer films remain resistant to blistering and flaking up to fluence of 8·1016 cm−2. The investigations have shown influence of the crystalline and amorphous layer thicknesses on the character and damage degree of the multilayer films surface as a result of post-radiation annealing at 600 °C. In this work potential processes (mechanisms) of blister formation and flacking in ZrN/SiNx multilayer systems are discussed.

Skyrmions are nanoscale spin configurations with topological properties that hold great promise for spintronic devices. Here, we establish their N\'eel texture, helicity, and size in Ir/Fe/Co/Pt multilayer films by constructing a multipole expansion to model their stray field signatures and applying it to magnetic force microscopy (MFM) images. Furthermore, the demonstrated sensitivity to inhomogeneity in skyrmion properties, coupled with a unique capability to estimate the pinning force governing dynamics, portends broad applicability in the burgeoning field of topological spin textures., Comment: 6 pages, 4 figures, significantly revised and upgraded. For the updated supplementary material please contact one of the corresponding authors

A high-resolution hard x-ray microscope is described. This system is capable of detecting line features as small as 0.6 micrometer in width, and resolving line pairs 1.2 micrometers wide and 1.2 micrometers apart. Three types of two-dimensional image detectors are discussed and compared for use with hard x rays in high resolution. Principles of x-ray image magnification are discussed, based on x-ray optics and diffraction physics. Examples of applications are shown in microradiography with fiber reinforced composite materials (SiC in Ti3Al Nb) and in diffraction imaging (topography) with device patterns on a silicon single crystal. High-resolution tomography has now become a reality.

In our work we focused on the electroactive and electrocatalytic properties of multilayer films formed from polyelectrolytes (PE) and Prussian blue nanoparticles (PBn), enhanced by addition of reduced graphene oxide (rGO). Films containing poly(allylamine hydrochloride) (PAH) and PBn were constructed using the layer-by-layer adsorption method. Graphene oxide (GO) was deposited from its aqueous suspension forming additional layers of the film. Then they were exposed to the elevated temperature, 180 °C to turn graphene oxide into its reduced form. We demonstrated, by cyclic voltamperometry, that the presence of conductive rGO greatly enhanced the electroactive properties of the PE/PB multilayer films. Simultaneously, they were also up to 40 times more effective for the electrocatalytic redox processes of hydrogen peroxide.

Indium-tin-oxide (ITO) thin films were prepared by reactive magnetron sputtering; their optical constants and thickness were determined by spectral reflectometry (SR) in the wavelength range from 400 nm to 800 nm and spectroscopic ellipsometry (SE) in the wavelength range from 191 nm to 1690 nm. A comparative evaluation of the measured data from SR and SE has been made using the same single layer optical model based on the Cauchy dispersion relation. The introduction of a surface roughness layer into the optical model considerably improved the fit quality during evaluation of SE data. Vertical inhomogeneity of the ITO thin films was assessed using a multilayer optical model describing porosity gradient and the three-layer optical model suggested by Jung [Y.S. Jung, Thin Solid Films 467, 36 (2004)] from the SE data. Copyright � 2014 Materials Research Society.

The present research reports on the development of bi- and multilayer polylactide (PLA) films by the incorporation of electrospun nanostructured PLA coatings and interlayers containing the antioxidant gallic acid (GA) at 40 wt% onto cast-extruded PLA films. To achieve the bilayer structures, submicron GA-loaded PLA fibers were applied on 200-&micro, m cast PLA films in the form of coatings by electrospinning for 1, 2, and 3 h. For the multilayers, the cast PLA films were first coated on one side by electrospinning, then sandwiched with 10-&micro, m PLA film on the other side, and the resultant whole structure was finally thermally post-treated at 150 &deg, C without pressure. Whereas the bilayer PLA films easily delaminated and lacked transparency, the multilayers showed sufficient adhesion between layers and high transparency for deposition times during electrospinning of up to 2 h. The incorporation of GA positively contributed to delaying the thermal degradation of PLA for approximately 10 &deg, C, as all films were thermally stable up to 345 &deg, C. The in vitro release studies performed in saline medium indicated that the GA released from the bilayer PLA films rapidly increased during the first 5 h of immersion while it stabilized after 45&ndash, 250 h. Interestingly, the PLA multilayers offered a high sustained release of GA, having the capacity to deliver the bioactive for over 1000 h. In addition, in the whole tested period, the GA released from the PLA films retained most of its antioxidant functionality. Thus, during the first days, the bilayer PLA films can perform as potent vehicles to deliver GA while the multilayer PLA films are able to show a sustained release of the natural antioxidant for extended periods.

The preparation of urea (bonded) cross-linked multilayer thin films by sequential deposition of bifunctional and tetrafunctional molecular building blocks is demonstrated. Multilayer growth as a function of deposition cycles was inspected using UV-vis absorption spectroscopy. From infrared results, three characteristic infrared bands of amide I, amide II, and asymmetric νa(N-C-N) stretching confirmed the formation of polyurea networks by alternate dipping into solutions of amine and isocyanate functionality monomers. The deconvoluted component of the C 1s and N 1s spectra obtained by X-ray photoelectron spectroscopy shows clear evidence of stable polyurea networks. The enhancement of structural periodicity with film growth was demonstrated by grazing-incidence small-angle X-ray scattering measurements. The thin film near the substrate surface seems to have an amorphous structure. However, molecular ordering improves in the surface normal direction of the substrate with a certain number of deposited layers. Constant mass density was not observed with deposition cycles. The mass density increased up to 16% within deposited layers from proximate layers to those extending away from the substrate surface. This difference in the packing density might derive from the different degrees of cross-linking among layers proximate to the substrate surface and extending away from the substrate surface.

Biomedical implant failure arises mainly from the degradation caused by tribological processes occurring in the corrosive environment the human body represents, known as tribocorrosion. The material loss and metal ion release resulting from tribocorrosion processes compromise the biocompatibility of metallic implants. The deposition of protective coatings on metallic substrates is a promising solution to overcome this problem. Pure titanium (Ti-cp) is widely used as an implant material due to its excellent corrosion resistance and high biocompatibility. However, its mechanical properties must be improved in order to ensure a longer durability. For this purpose, TaN monolayer and multilayer coatings were deposited on medical grade Ti-cp to enhance its tribocorrosion performance in simulated body fluids. TaN coatings were deposited by recently developed High Power Pulsed Magnetron Sputtering (HPPMS) technique. HPPMS enables the deposition of extremely dense coatings with superior properties compared to the ones grown by conventional sputtering. Columnar-free TaN monolayer and multilayer films were developed exhibiting corrosion resistances in the MΩ range, one order of magnitude higher than for Ti-cp. Friction coefficient of Ti-cp was reduced from 0.58 to 0.25 while wear rate was considerably decreased. The determined material loss after tribocorrosion tests for Ti-cp was 0.4 mm. It was reduced up to 1.55 × 10 mm by the application of best-performing TaN multilayer film., Financial support of this research program from the Basque Government (EMAITEK program) and Spanish National Department of the Education and Science in the projects: CSD2008-00323 FUNCOAT and MAT2014-57547-R is gratefully acknowledged.

Short (5 min) post-deposition thermal treatments under magnetic field at low temperature (up to 200 °C) performed in exchange-coupled FeNi(40 nm)/FeMn(20 nm) bilayer thin films prepared by magnetron sputtering are shown to be effective to significantly modify their exchange field (from around 40 Oe down to 27 Oe) between FeNi and FeMn layers. A similar exchange field decrease was observed for the first deposited FeNi layer of the FeNi(40 nm)/FeMn(20 nm)/FeNi(40 nm) trilayer films after the same thermal treatments. The exchange field value for the second FeNi layer was not substantially changed. The X-ray diffraction patterns indicates that such a heat treatment has no effect on the grain size and crystalline texture of the films, while atomic force microscope studies reveal an increase of the surface roughness after the treatment which is more noticeable in the case of the trilayer film. Analysis of the experimental results leads us to conclude that the variations of the exchange field after heat treatment are likely caused by a modification of interfacial roughness and/or interfacial magnetic structure, but unlikely by the changes in the microstructure and/or changes of composition of the antiferromagnetic FeMn layer., This work was supported by the Ministry of Education and Science of the Russian Federation (Project No. 1362), and ACTIMAT project of Etortek program of the Basque Government and UPV-EHU. Support from Spanish MINECO under project MAT2013-48059-C2-1-R is also acknowledged.

A key challenge in the preparation of nanoplatelet-filled polymer composites is the ability to realize the nanometer-level dispersion and the planar orientation of nanosheets in polymer matrices. In this report, multilayer films were successfully fabricated by layer-by-layer assembly of regenerated cellulose and graphene oxide, in which graphene oxide nanosheets were used as the building blocks. The thickness of 50 layer film is about 20 μm and it exhibits a high degree of smoothness. This may be attributed to the well-defined layered structure with high degree of planar orientation and nanolevel assemblies of graphene oxide nanosheets in the polymer matrices. Typical field emission scanning electron microscope images demonstrate an ordered arrangement of layers. The electrical conductivity of the multilayer films shows a remarkable increase with increasing layer of the films. A significant enhancement of mechanical properties has been achieved, that is, a 110.8% improvement of elastic modulus and a 262.5% increase of hardness respectively.

International audience; A tunable strategy, based on the combination of Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and the Layer by Layer (LbL) deposition of polyelectrolytes, was exploited to design tailor-made polyelectrolyte multilayers (PEM) with unusual nanometric features. The cornerstone of the approach is to use polyelectrolytes grafted onto a planar inorganic substrate with different chain conformations as a template for depositing PEM. More particularly, tethered poly(trimethylammonium ethyl methacrylate iodide) (PTMAEMAI) grafts provide various 3D distributions of charge due to a conformation transition of the precursor quaternizable poly(N, N-dimethylamino)ethyl methacrylate (PDMAEMA) chains from 'pancake' to brush-like regime. The change of regime was ensured through the controlled variation of the graft molecular weight using SI-ATRP. The regions made of attached-polycations may serve as preferential positively charged anchoring sites and act as structure-directing agents for the subsequent LbL self-assembly of poly(sodium 4-styrenesulfonate) (PSS)/poly(diallyldimethylammonium chloride) (PDADMAC) multilayers. We have revealed the possibility to fine manipulate (i) the interaction abilities and (ii) the topology of (PSS/PDADMAC) films through the spatial organization exhibited by the PTMAEMAI grafts. This appears as a well-suited and straightforward tool to create an adjustable nanoscale patterning of the resulting multilayers.

When aqueous solutions of polycations and polyanions are mixed, polyelectrolyte complexes form. These are usually insoluble in water, so that they separate out as a new concentrated polymer phase, called a complex coacervate. The behavior of these complexes is reviewed, with emphasis on new measurements that shed light on their structural and mechanical properties, such as cohesive energy, interfacial tension, and viscoelasticity. It turns out that stoichiometric complexes can be considered in many respects as pseudo-neutral, weakly hydrophobic polymers, which are insoluble in water, but become progressively more soluble as salt is added. In fact, the solubility-enhancing effect of salt is quite analogous to that of temperature for polymers in apolar solvents. Since two-phase systems can be prepared in colloidal form, we also discuss several kinds of colloids or 'microphases' that can arise due to polyelectrolyte complexation, such as thin films, 'zipper' brushes, micelles, and micellar networks. A characteristic feature of these charge-driven two-phase systems is that two polymeric ingredients are needed, but that some deviation from strict stoichiometry is tolerated. This turns out to nicely explain how and when the layer-by-layer method works, how a 'leverage rule' applies to the density of the 'zipper brush', and why soluble complexes or micelles appear in a certain window of composition. As variations on the theme, we discuss micelles with metal ions in the core, due to incorporation of supramolecular coordination polyelectrolytes, and micellar networks, which form a new kind of physical gels with unusual properties.

This article is part of the Supramolecular Chemistry at Interfaces special issue. The layer-by-layer (LbL) assembly of salt-containing nonstoichiometric polyelectrolyte complexes (PECs) with oppositely charged uncomplexed polyelectrolyte for the fabrication of dewetting-induced porous polymeric films has been systematically investigated. Salt-containing poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) complexes (noted as PAH-PAA) with a molar excess of PAH were LbL assembled with polyanion poly(sodium 4-styrenesulfonate) (PSS) to produce PSS/PAH-PAA films. The structure of the PAH-PAA complexes is dependent on the concentration of NaCl added to their aqueous dispersions, which can be used to tailor the structure of the LbLassembled PSS/PAH-PAA films. Porous PSS/PAH-PAA films are fabricated when salt-containing PAH-PAA complexes with a large amount of added NaCl are used for LbL assembly with PSS. In-situ and ex-situ atomic force microscopy measurements disclose that the dewetting process composed of pore nucleation and pore growth steps leads to the formation of pores in the LbL-assembled PSS/PAH-PAA films. The present study provides a facile way to fabricate porous polymeric films by dewetting LbL-assembled polymeric films comprising salt-containing PECs. Refereed/Peer-reviewed

In this paper, we numerically demonstrate mid-IR nearly perfect resonant absorption and coherent thermal emission for both polarizations and wide angular region using multilayer designs of unpatterned films of hexagonal boron nitride (hBN). In these optimized structures, the films of hBN are transferred onto a Ge spacer layer on top of a one-dimensional photonic crystal (1D PC) composed of alternating layers of KBr and Ge. According to the perfect agreements between our analytical and numerical results, we discover that the mentioned optical characteristic of the hBN-based 1D PCs is due to a strong coupling between localized photonic modes supported by the PC and the phononic modes of hBN films. These coupled modes are referred as Tamm phonons. Moreover, our findings prove that the resonant absorptions can be red-or blue-shifted by changing the thickness of hBN and the spacer layer. The obtained results in this paper are beneficial for designing coherent thermal sources, light absorbers, and sensors operating within 6.2 mu m to 7.3 mu m in a wide angular range and both polarizations. The planar and lithography free nature of this multilayer design is a prominent factor that makes it a large scale compatible design. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

The layer-by-layer (LbL) adsorption technique allows construction of polyelectrolyte (PE) multilayer films with precisely defined properties and that opens a wide range of applications, where such materials can be used. One of the most important factors governing structure and interfacial properties of polyelectrolyte films is electrolyte concentration and pH of the PE solutions. In the present work we have focused our attention on multilayer films formed using combination of weak polyelectrolytes, PAH/PAA, whose charge can be tuned during the film preparation by pH of their solutions. PE films were formed by LbL technique on silicon wafers, Si/SiO 2 , and were characterized by ellipsometry, neutron reflectometry and AFM. Additionally quartz crystal microbalance (QCM) was used to determine mass of the films formed on the gold covered QCM crystals. We have found that the thickest films were formed when both polyelectrolytes were weakly charged, while the thinnest films were obtained for fully charged PAH and PAA. However, for the combination of weakly and strongly charged polyelectrolyte the non-monotonic increase of film thickness with a number of deposited PE layers was observed. We hypothesize, that it results from PE reorganization and formation of surface complexes during adsorption of polyelectrolyte layers.

The irreversibility temperatures were measured for a-axis oriented and c-axis in-plane aligned Y123/Pr123 multilayer films in various magnetic fields. Pr123 layers act as two-dimensional (planer) c-axis correlated artificial pinning centers (APCs) in the multilayer films. In the irreversibility field-temperature (B irr - T) curves, the crossover was observed near matching field B phi for the multilayer films, when the magnetic fields were applied parallel to the c -axis of the film (B//c). It is suggested the vortex state in Y123 films with two-dimensional APCs is Bose glass below the crossover field. The B irr - T curves under B // a shifted toward lower temperature and magnetic field regions.

In recent decades, polymers have experienced a radical evolution: from being used as inexpensive materials in the manufacturing of simple appliances to be designed as nanostructured devices with important applications in many leading fields, such as biomedicine at the nanoscale. Within this context, polymeric free-standing nanomembranes - self-supported quasi-2D structures with a thickness ranging from similar to 10 to a few hundreds of nanometers and an aspect ratio of size and thickness greater than 10(6) - are emerging as versatile elements for applications as varied as overlapping therapy, burn wound infection treatment, antimicrobial platforms, scaffolds for tissue engineering, drug-loading and delivery systems, biosensors, etc. Although at first, a little over a decade ago, materials for the fabrication of free-standing nanosheets were limited to biopolymers and insulating polymers that were biodegradable, during the last five years the use of electroactive conducting polymers has been attracting much attention because of their extraordinary advantages in the biomedical field. In this context, a systematic review of current research on polymeric free-standing nanomembranes for biomedical applications is presented. Moreover, further discussion on the future developments of some of these exciting areas of study and their principal challenges is presented in the conclusion section.

TSeveral polymers can be combined in one multilayer structure by reactive coextrusion. Tie-layers are often used to compatibilize adjacent layers and may reduce or suppress interfacial instabilities and defects in multilayer coextrusion flow. However, a new additional defect defined as “grainy” defect can be observed. In our best of knowledge, no study in literature has been dedicated to understand its origin. The phenomena are quite complex due to the coupling of the effects of flow and the physico-chemical mechanisms at the interface. The aim of this work is to understand the relationship between the instabilities and defects encountered in multilayer coextruded films and the role of the copolymer formed in-situ between tie and barrier layers. Polyamide 6 (PA6) and ethylene-vinyl alcohol copolymer (EVOH) were used as barrier layers sandwiched in polypropylene (PP) with or without tie-layer based on polypropylene grafted maleic anhydride (PP-g-MA). Influence of process parameters and nature of the polymer pair on the generation of “grainy” defect has been assessed and related to the rheological and the physico-chemical properties of layers. These experiments showed that this defect appeared mainly in the compatibilized EVOH system and could be distinguished from the usual coextrusion instabilities. Interfacial properties between tie and barrier layers have been investigated. Shear stress relaxation experiments have been carried out on reactive tie/barrier bilayers. Due to the interphase generated in-situ, the relaxation behavior was altered by extending the relaxation time. Investigation of interfacial morphology highlighted that the copolymer architecture significantly affected the interface/interphase development and interface roughness. Hence, relationships between relaxation process, interfacial morphology and copolymer structure were correlated with the generation of grainy defects in coextrusion.

International audience; Layer by Layer (LbL) thin films stemming from the formation of stereocomplex between oligolactate of opposite chirality (OLLA and ODLA) covalently anchored onto poly(vinyl alcohol) (PVA) chains is described herein for the first time. The feasibility to construct films by sequential adsorption of PVA-g-ODLA and PVA-g-OLLA graft copolymers is undertaken through the exploitation of two different film deposition techniques, namely dip-and spin-assisted processes. For both deposition methods, infrared spectroscopy in ATR mode reveals a progressive accumulation of matter on the flat substrate during the successive cycle depositions and proves that co-crystallisation involving the two homochiral copolymers is the main driving force for the step by step film build up. Also, the effect of the deposition technique is assessed on the film features in terms of (i) growth mechanism, (ii) internal organization and (iii) surface topology. The strong centrifugal forces associated with fast solvent elimination acting during spinning lead to thinner film with more uniform and homogeneous surface morphology in a much shorter time, than the ones resulting from the dip-assisted process. Such LbL nanometric films, induced by OLLA/ODLA interfacial stereocomplexation, open promising perspectives in the field of biodegradable self-assembled films.

The barrier performance of multilayer polymeric films for food applications has been significantly improved by incorporating oxygen scavenging materials. The scavenging activity depends on parameters such as diffusion coefficient, solubility, concentration of scavenger loaded and the number of available reactive sites. These parameters influence the barrier performance of the film in different ways. Virtualization of the process is useful to characterize, design and optimize the barrier performance based on physical configuration of the films. Also, the knowledge of values of parameters is important to predict the performances. Inverse modeling and sensitivity analysis are sole way to find reasonable values of poorly defined, unmeasured parameters and to analyze the most influencing parameters. Thus, the objective of this work was to develop a model to predict barrier properties of multilayer film incorporated with reactive layers and to analyze and characterize their performances. Polymeric film based on three layers of Polyethylene terephthalate (PET), with a core reactive layer, at different thickness configurations was considered in the model. A one dimensional diffusion equation with reaction was solved numerically to predict the concentration of oxygen diffused into the polymer taking into account the reactive ability of the core layer. The model was solved using commercial software for different film layer configurations and sensitivity analysis based on inverse modeling was carried out to understand the effect of physical parameters. The results have shown that the use of sensitivity analysis can provide physical understanding of the parameters which highly affect the gas permeation into the film. Solubility and the number of available reactive sites were the factors mainly influencing the barrier performance of three layered polymeric film. Multilayer films slightly modified the steady transport properties in comparison to net PET, giving a small reduction in the permeability and oxygen transfer rate values. Scavenging capacity of the multilayer film increased linearly with the increase of the reactive layer thickness and the oxygen absorption reaction at short times decreased proportionally with the thickness of the external PET layer.

Herein, hydroxypropyl-beta-cyclodextrin (HP beta CD) inclusion complex (IC) of a hydrophobic drug, sulfisoxazole (SFS) was incorporated in hydroxypropyl cellulose (HPC) nanofibers (HPC/SFS/HP beta CD-IC-NF) via electrospinning. SFS/HP beta CD-IC was characterized by DSC to investigate the formation of inclusion complex and the stoichiometry of the complex was determined by Job's plot. Modeling studies were also performed on SFS/HP beta CD-IC using ab initio technique. SEM images depicted the defect free uniform fibers and confirmed the incorporation of SFS/HP beta CD-IC in nanofibers did not alter the fiber morphology. XRD analyses showed amorphous distribution of SFS/HP beta CD-IC in the fiber mat. Release studies were performed in phosphate buffered saline (PBS). The results suggest higher amount of SFS released from HPC/SFS/HP beta CD-IC-NF when compared to free SFS containing HPC nanofibers (HPC/SFS-NF). This was attributed to the increased solubility of SFS by inclusion complexation. Sandwich configurations were prepared by placing HPC/SFS/HP beta CD-IC-NF between electrospun PCL nanofibrous mat (PCL-HPC/SFS/HP beta CD-IC-NF). Consequently, PCL-HPC/SFS/HP beta CD-IC-NF exhibited slower release of SFS as compared with HPC/SFS/HP beta CD-IC-NF. This study may provide more efficient future strategies for developing delivery systems of hydrophobic drugs. (C) 2015 Elsevier B.V. All rights reserved.

A mathematical model that predicts the water-permeability coefficient of multilayer films intended for food-packaging applications is presented. A 6-layer film composed of 5 polyolefinic layers and a layer made of a copolymer of ethylene and vinylalcohol (EVOH) was used to validate the proposed model. Water-permeability tests were run at 25°C both on each single layer and on the multilayer film; whereas the water-sorption isotherm and the water-sorption kinetics were determined only for the EVOH layer. Results suggest that the water-permeability coefficient of multilayer films can be predicted from the knowledge of the water-transport properties of each constituent layer.

In a marine environment, specific proteins are secreted by mussels and used as a bioglue to stick to a surface. These mussel proteins present an unusual amino acid 3,4-dihydroxyphenylalanine (known as DOPA). The outstanding adhesive properties of these materials in the sea harsh conditions have been attributed to the presence of the catechol groups present in DOPA. Inspired by the structure and composition of these adhesive proteins, we used dopamine-modified hyaluronic acid (HA-DN) prepared by carbodiimide chemistry to form thin and surface-adherent dopamine films. This conjugate was characterized by distinct techniques, such as nuclear magnetic resonance and ultraviolet spectrophotometry. Multilayer films were developed based on chitosan and HA-DN to form polymeric coatings using the layer-by-layer methodology. The nanostructured films formation was monitored by quartz crystal microbalance. The film surface was characterized by atomic force microscopy and scanning electron microscopy. Water contact angle measurements were also conducted. The adhesion properties were analyzed showing that the nanostructured films with dopamine promote an improved adhesion. In vitro tests showed an enhanced cell adhesion, proliferation and viability for the biomimetic films with catechol groups, demonstrating their potential to be used in distinct biomedical applications., The authors want to acknowledge the COST Action TD0906 - Biological adhesives: from biology to biomimetics. The authors also acknowledge the financial support from the Fundacao para a Ciencia e para a Tecnologia through the Ph.D. grants with the references SFRH/BD/73119/2010 and SFRH/BD/69529/2010. G. G. Ferrer acknowledges the support of the Spanish Ministry of Science and Innovation for the mobility grant JC2008-00135. G. Botelho acknowledges the NMR portuguese network (PTNMR, Bruker Avance III 400-Univ. Minho).

The lanthanide-containing Keggin-type polyoxometalates (LnPOMs), [Ln(PINi O-39)(2)](11)-(Ln=Eu3+ and Sm3+), were incorporated for the first ime into porous chromium terephthalate MIL-101(Cr) via an impregnation method, originating two unprecedented composite materials, Eu(PIN11)(2)@MIL and Sm(PW11)(2)@MIL, to be used as heterogeneous catalysts. The characterization of these new composites was performed by vibrational spectroscopy (FT-IR and FT-Raman), powder X-ray diffraction (XRD), elemental analysis, UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and textural analysis. Ln(PW11)(2)@MIL materials were tested as heterogeneous catalysts in the oxidation of styrene using hydrogen peroxide as the oxidant and acetonitrile as the solvent. Their catalytic activity was also compared with the homogeneous LnPOM(5) catalysts in order to evaluate the effect of their incorporation on the catalytic activity. The composite materials exhibit higher catalytic activities toward the oxidation of styrene than the corresponding isolated LnPOM(5) with complete conversion of the substrate after 4 h and 5 h for the samarium and europium composites, respectively. Furthermore, microwave-assisted oxidative reactions were also performed showing an increase in the selectivity values while maintaining similar conversion values, especially in the heterogeneous reactions. (C) 2013 Elsevier B.V. All rights reserved.

Bu çalışma, 29 Nisan-4 Mayıs 2012 tarihlerinde İstanbul[Türkiye]'da düzenlenen 3. International Conference on Superconductivity and Magnetism (ICSM)'de bildiri olarak sunulmuştur. The effect of NaOH with different concentrations on CoFe/Cu multilayer films was studied between pH=3.70 and pH=2.70. The effect of different electrolyte pH from 3.7 to 2.7, which was obtained at various NaOH concentrations, on CoFe/Cu multilayer films was studied. The structural studies by x-ray diffraction (XRD) revealed that the multilayers have face-centered cubic structure. The preferential orientation of the multilayer is in the (220), (111), (111), and (222) direction at pH=3.7,3.3,3.0 and 2.7, respectively. It was observed that at pH=3.0, the film composition, by energy dispersive x-ray spectroscopy (EDX), contains 3.22 at. Co % and 96.78 at. Cu %, and at low pH (2.7), 10.58 at. Co %, 4.18 at. Fe % and 85.24 at. Cu %. Magnetoresistance measurements made at room temperature showed that all films exhibited giant magnetoresistance (GMR), which was affected by the electrolyte pH. The observed GMR values are 4.0 %, 4.6 %, 4.2 %, and 12 % at the pH values of 3.7, 3.3, 3.0 and 2.7, respectively. Magnetic measurements of the films were made at +/- 20 kOe by using ADE EV 9 model a vibrating sample magnetometer. The magnetic measurements revealed that the coercivity of the films increased from 70 Oe to 93 Oe and stayed there, and the saturation magnetization monotonically increased form 7.40 emu/g to 17.05 emu/g with decreasing electrolyte pH from 3.7 to 2.7.

We report an experimental study on the growth and adsorption kinetics of polyelectrolyte multilayers (PEMs). PEMs composed of poly(diallyldimethyl ammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS), and of poly(allylamine hydrochloride) (PAH) and PSS polyelectrolyte pairs were built and studied via dissipative quartz crystal microbalance (D-QCM) and ellipsometry. The results have pointed out that the growth trend of PEMs may be controlled by the assembly conditions that modify the layer structure and subsequently the film features. The study of adsorption kinetics of the layers suggests that, even though interdiffusion may take place during the growth of PEMs, it does not determine the growth mechanism. Analysis of the mechanical properties allows confirmation of the scenario proposed for the explanation of the PEMs growth. Independent of growth type, the adsorption kinetics of the layers is a bimodal process. The results here presented allow us to rule out any correlation between growth mechanism and adsorption dynamics. Fil: Guzmán, Eduardo. Universidad Complutense de Madrid; España Fil: Ritacco, Hernán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Ortega, Francisco. Universidad Complutense de Madrid; España Fil: Rubio, Ramón G.. Universidad Complutense de Madrid; España

Al-doped ZnO (AZO)/Ag/AZO multilayer coatings (50-70 nm thick) were grown at room temperature on glass substrates with different silver layer thickness, from 3 to 19 nm, by using radio frequency magnetron sputtering. Thermal stability of the compositional, optical and electrical properties of the AZO/Ag/AZO structures were investigated up to 400 °C and as a function of Ag film thickness. An AZO film as thin as 20 nm is an excellent barrier to Ag diffusion. The inclusion of 9.5 nm thin silver layer within the transparent conductive oxide (TCO) material leads to a maximum enhancement of the electro-optical characteristics. The excellent measured properties of low resistance, high transmittance in the visible spectral range and thermal stability allow these ultra-thin AZO/Ag/AZO structures to compete with the 1 μm thick TCO layer currently used in thin film solar cells. © 2012 Elsevier B.V. All rights reserved.

Take a metal powder and add aqueous hydrogen peroxide and a small amount of acetic acid (10:1 ratio) under ambient conditions and, in one simple step, colloidally stable dispersions of nanoparticle (NP) metal oxides of the respective metals form with diameters in the range approx. 3–8 nm. No complex work-up or time-consuming purification is required, just simple filtration and spin-coating to make a nanopar ticle metal oxide thin film. Furthermore, this straightforward approach avoids expensive organic surfactants, capping ligands and solvents, metal salts, coordination compounds, and sol–gel precursors commonly used in prior reported syntheses of metal oxide nanoparticles that often contaminate and therefore complicate their subsequent utilization. [1,2] This facile synthetic strategy provides a universal, clean, green, and simple approach to metal oxide nanoparticles, as well as single and multilayer metal oxide nanoparticle porous films perceived to provide diverse applications such as lithium batteries, solar and photoelectrochemical cells, electrochromics and sensors, photocatalysts, and photonic crystals. [3−7] Metal oxide nanoparticles and thin films thereof offer distinctive and desirable properties that make them attractive candidates for materials science and biomedical applications. [8] The synthesis begins with micrometer-scale metal powders exemplified by W, Mo, Ni, Co, Fe, Zn, and Mg (purity 99.5 to 99.95%) which dissolve in aqueous/H 2 O 2 (30 wt%) and acetic acid, AcH. (DANGER: Very exothermic reaction, instant ice-bath cooling is necessary in a well ventilated fumehood. Protective glasses, gloves, and a lab coat must be worn all the time during this synthetic procedure.) Contingent upon the choice of metal(s), this results in highly stable, single (M 1 O x ), binary Spinel (M 1 M 2 O 4 ) and ternary multi-metallic (M1M2M3Oz) aqueous dispersions of colloidally stable metal

dation. Here, we study the effect of the oxidation level on nonlinear optical properties of GO. We demonstrate that both electrochemically induced reversible reduction and optically induced photoreduction in GO result in changes in the nonlinear optical properties of GO thin films. We present the carrier dynamics and nonlinear optical properties of such films, studied by ultrafast wavelength-dependent pumpprobe spectroscopy. We show that ultrafast response of GO can be tuned by both reduction procedure. The preparation, characterization, linear optical, and electrochromism properties of GO were very recently reported. 10 We study the electrical reduction in GO in air, using multilayer GO thin films deposited on metalized glass substrates. The two terminal devices consist of thin 10‐50 nm Pd/Au planar contacts, separated by 0.3‐0.6 mm, with a thin multilayer GO film covering both contacts and in between Fig. 1a. The degree of chemical reduction and linear absorption spectrum can be tuned by applying a