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The depletion of selected substituted phenol stabilizers from systems simulating self-etching dental adhesives is studied. If the adhesive monomer is an acrylate derivative, the stabilizer disappears quickly. Experimental results support the hypothesis that the phenol stabilizers are depleted from the system via a non-radical reaction with the acrylic double bond in addition to the free-radical mechanism. The C-conjugate addition of aryloxide anions to the acrylate double bonds (the Michael reaction) is proposed as the reaction mechanism. The rate of the acid-catalyzed Michael addition between acrylate monomers and phenolic stabilizers depends on the strength of the acidic catalyst. [ABSTRACT FROM AUTHOR]

The subject of the article is a physical-mechanical analysis of waterproofing materials exposed to an external environment. Physical and mechanical properties have a direct impact on the life of waterproofing materials and their later remediation. In the introduction, the factors influencing the properties of waterproofing materials are presented. The main part of the article covers the basic possibilities of testing the materials testing the materials, normative testing conditions, and critical aspects of their implementation. In this article we deal with the laboratory testing of a waterproofing membrane based on PVC-P in terms of its degradation from UV radiation, humidity, and the temperature. [ABSTRACT FROM AUTHOR]

The effect of humidity on sheep wool during irradiation by an accelerated electron beam was examined. Each of the samples with 10%, 53%, and 97% relative humidity (RH) absorbed a dose of 0, 109, and 257 kGy, respectively. After being freely kept in common laboratory conditions, the samples were subjected to batch Co(II) sorption experiments monitored with VIS spectrometry for different lapses from electron beam exposure. Along with the sorption, FTIR spectral analysis of the wool samples was conducted for cysteic acid and cystine monoxide, and later, the examination was completed, with pH measuring 0.05 molar KCl extract from the wool samples. Besides a relationship to the absorbed dose and lapse, the sorptivity results showed considerable dependence on wool humidity under exposure. When humidity was deficient (10% RH), the sorptivity was lower due to limited transformation of cystine monoxide to cysteic acid. The wool pre-conditioned at 53% RH, which is the humidity close to common environmental conditions, demonstrated the best Co(II) sorptivity in any case. This finding enables the elimination of pre-exposure wool conditioning in practice. Under excessive humidity of 97% RH and enough high dose of 257 kGy, radiolysis of water occurred, deteriorating the sorptivity. Each wool humidity, dose, and lapse showed a particular scenario. The time and humidity variations in the sorptivity for the non-irradiated sample were a little surprising; despite the absence of electron irradiation, relevant results indicated a strong sensitivity to pre-condition humidity and lapse from the start of the monitoring. [ABSTRACT FROM AUTHOR]

Photo‐oxidation of syndiotactic polypropylene–sPP/organoclay nanocomposites was performed. Nanocomposites were prepared in situ by melt compounding of sPP, compatibilizer (iPP grafted with maleic anhydride–iPP‐g‐MAN) and organoclay filler ME C18 (modified with octadecyl ammonium chains in intergaleries of layered silicate, of which silicate layers (about 1 nm thin) were exfoliated). The influence of ME C18 nanoparticles alone (in content region 1 to 15 wt%) and together with compatibilizer iPP‐g‐MAN on the photostability of the sPP nanocomposite was studied. It was found that the silicate ME C18 nanoparticles alone catalyze the photooxidation and shorten the induction period of photo‐oxidation to one fourth (at the content of 5 wt% of ME C18) in comparison with unfilled sPP) and the presence of compatibilizer supports the photo‐oxidation of sPP nanocomposite. The ME C18 nanoparticles decrease the efficiency of UV stabilizers. The rate of photo‐oxidation of sPP/clay nanocomposite after the induction period is significantly higher than unfilled sPP. The mechanism of photo‐oxidation is discussed. [ABSTRACT FROM AUTHOR]

Novel alginate-based binders containing either catechol (d-Alg) or sulfonate (s-Alg) functional groups were developed and characterized to improve the capacity decay performance and better stability of Li-ion batteries. The electrochemical performance of silicon–graphite (Si/Gr) anode with alginate-based binders were compared to the commonly used CMC/SBR binder. The active material in the anodes was the ball-milled Si/Gr (20:80 wt%) powder mixture. A comprehensive electrochemical study was carried out through rate capability test, cycle test, differential capacity analysis (dQ/dV), and electrochemical impedance spectroscopy (EIS). The functionalized s-Alg binder showed the lowest electrolyte uptake (11.5%) and the highest tensile strength (97 MPa). Anodes with s-Alg exhibited high initial capacity (1250 mAh g−1) and improved decay performance (580 mAh g−1 at 0.2 C), by ~ 65% higher compared to CMC/SBR binder. The influence of pH value of s-Alg binder preparation showed that anodes prepared at pH 3 of s-Alg exhibit better performance, reaching 800 and 750 mAh g−1 at 0.1 and 0.2 C, respectively, due to the stronger bonding formation and compactness of anode layer which providing low charge transfer and solid electrolyte interface resistance. [ABSTRACT FROM AUTHOR]

Here we present a new effective antibacterial material suitable for a coating, e.g., surface treatment of textiles, which is also time and financially undemanding. The most important role is played by hydrophobic carbon quantum dots, as a new type of photosensitizer, produced by carbonization of different carbon precursors, which are incorporated by swelling from solution into various polymer matrices in the form of thin films, in particular polyurethanes, which are currently commercially used for industrial surface treatment of textiles. The role of hydrophobic carbon quantum dots is to work as photosensitizers upon irradiation and produce reactive oxygen species, namely singlet oxygen, which is already known as the most effective radical for elimination different kinds of bacteria on the surface or in close proximity to such modified material. Therefore, we have mainly studied the effect of hydrophobic carbon quantum dots on Staphylococcus aureus and the cytotoxicity tests, which are essential for the safe handling of such material. Also, the production of singlet oxygen by several methods (electron paramagnetic spectroscopy, time-resolved near-infrared spectroscopy), surface structures (atomic force microscopy and contact angle measurement), and the effect of radiation on polymer matrices were studied. The prepared material is easily modulated by end-user requirements. • Light-triggered antibacterial nanoparticles and photodynamic therapy. • Singlet oxygen produced by carbon quantum dots in a polymer matrix. • Prevention in bacterial resistance using smart polymer materials. [ABSTRACT FROM AUTHOR]

We examined the characteristics of an electron beam irradiated wool with an absorbed dose of (21–410) kGy in comparison with natural wool with respect to the determination of the isoelectric point (IEP), zero charge point (ZCP), mechanism of Cr(III) sorption from higher concentrated solutions, and the modelling of the wool-Cr(III) interaction. The data of ZPC and IEP differed between natural and irradiated samples. Increasing the dose shifted the pH of ZPC from 6.85 for natural wool to 6.20 for the highest dosed wool, while the natural wool IEP moved very little, from pH = 3.35 to 3.40 for all of the irradiated samples. The sorption experiments were performed in a pH bath set at 3.40, and the determination of the residual Cr(III) in the bath was performed by VIS spectrometry under optimized conditions. The resulting sorptivity showed a monotonically rising trend with increasing Cr(III) concentration in the bath. Lower doses, unlike higher doses, showed better sorptivity than the natural wool. FTIR data indicated the formation of complex chromite salts of carboxylates and cysteinates. Crosslinks via ligands coming from different keratin chains were predicted, preferably on the surface of the fibers, but to a degree that did not yet inhibit the diffusion of Cr(III)-cations into the fiber volume. We also present a concept of a complex octahedral structure. [ABSTRACT FROM AUTHOR]

Industrially important properties of wood can be changed due to the modification of birch wood (Betula pendula L.) after the process of thermal treatment with saturated water steam. The birch wood was modified by saturated water steam at 125 ± 2.5 °C for 8 hours and at a pressure of 0.18 MPa. The water contact angle of steam-treated birch wood increased from 42.1° (for untreated birch wood) to 52.4° (for steam-treated birch wood), and the stability of water drop on steam-treated birch wood surface increased. FTIR spectra showed an increase in C=O and glycoside bonds concentration on the surface of steam-treated birch wood, but the concentration of C-O-C groups decreased. XPS measurements confirmed that the concentration of oxygen as well as C=O and C-O-O groups on the surface of steamtreated birch wood showed an increment in comparison with the native wood sample. SEM micro photos confirmed the minor changes of birch wood cells due to the action of saturated water steam modification. [ABSTRACT FROM AUTHOR]

Sorption of higher concentrations of Cu(II) solution onto natural sheep wool or wool irradiated by an electron beam was studied. Sorption isotherms were of unexpected character, showing extremes. The samples with lower absorbed doses adsorbed less than non-irradiated wool, while higher doses led to increased sorption varying with both concentration and dose. FTIR spectra taken from the fibre surface and bulk were different. It was concluded that there was formation of Cu(II)-complexes of carboxylic and cysteic acids with ligands coming from various keratin macromolecules. Clusters of chains crosslinked through the ligands on the surface limit diffusion of Cu(II) into the bulk of fibre, thus decreasing the sorption. After exhausting the available ligands on the surface the remaining Cu(II) cations diffuse into the keratin bulk. Here, depending on accessibility of suitable ligands, Cu(II) creates simple or complex salts giving rise to the sorption extremes. Suggestion of a mechanism for this phenomenon is presented. [ABSTRACT FROM AUTHOR]

Gel electrolytes for aluminum-air (Al-air) primary batteries were prepared based on hydroxyethyl cellulose (HEC) and acrylate monomers bearing differently charged functional groups (i.e., -COOCH 2 CH 2 N+(CH 3) 3 Cl−, -COO- and -COOCH 2 CF 3). The acrylate monomers were grafted from HEC backbone and crosslinked using methylenebisacrylamide (MBA) to obtain hydrogels with tuned mechanical (15–75 kPa), morphological (pore size 35–125 μm) properties and varied swelling degrees at alkaline electrolyte (900–2500%). Electrochemical measurements were performed on Al-air cells assembled from Al anode, gel electrolytes (in 1 M NaOH) and carbon-based air-cathodes containing silver fine particles (Ag-FPs). Hydrogels with quaternary ammonium salt (HEC-AEtMACl) showed very long discharge time (6.5 h) compared to 1.8 h with the fluorinated hydrogels (HEC-TFEMA) and 1.1 h with carboxylated hydrogels (HEC-AA). Also, HEC-AEtMACl showed the highest current peak (3.9 μA at 1.4 V). Polarization curves proved that the anodic polarization behavior is dominant resulting from the anodic parasitic reaction. The Electrochemical Impedance Spectroscopy (EIS) evidenced that HEC-TFEMA has ionic conductivity (34.4 mScm−1) higher than that of HEC-AEtMACl. However, the highest specific capacity was observed to HEC- AEtMACl 0.928 mA h/cm2 compared to 0.26 and 0.15 mA h/cm2 for HEC-TFEMA and HEC-AA respectively. • Gel electrolytes based on hydroxyethyl cellulose were prepared for Al-air batteries. • Charged-functional groups on hydrogels impact the discharging time significantly. • Positively charged hydrogel prevents the passivation layer on Al-anode. • Fluorinated hydrogels showed the highest ionic conductivity. [ABSTRACT FROM AUTHOR]

Development of new types of antimicrobial coatings is of utmost importance due to increasing problems with pathogen transmission from various infectious surfaces to human beings. In this study, new types of highly potent antimicrobial polyurethane composite films encapsulated by hydrophobic riboflavin-based carbon polymer dots are presented. Detailed structural, optical, antimicrobial, and cytotoxic investigations of these composites were conducted. Low-power blue light triggered the composites to eradicate Escherichia coli in 30 min, whereas the same effect toward Staphylococcus aureus was reached after 60 min. These composites also show low toxicity against MRC-5 cells. In this way, RF-CPD composites can be used for sterilization of highly touched objects in the healthcare industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface initiated photoATRP was optimized to achieve high thickness of brushes. • High fidelity of the polymer chain-ends was proven by grafting multiblock chains. • Versatility of the conditions was demonstrated on 3 types of hydrophilic monomers. • Antifouling properties were improved with thickness of the PHEMA brushes. The recent development of sustainable chemistry motivates scientists to develop economically favourable, highly efficient, and environmentally friendly polymerization techniques. This contribution demonstrates a facile fabrication of hydrophilic polymer brushes via surface-initiated photochemically induced atom transfer radical polymerization using a copper catalyst in low concentrations and microlitre volume of polymerization mixture (SI-μL-CuPhotoATRP). The fabrication proceeds by sandwiching of μL reaction solution between a Si-wafer modified with ATRP-initiator and a glass slide under atmospheric and ambient conditions. Optimization of reaction conditions was realized on hydrophilic monomer such as 2-hydroxyethyl methacrylate (HEMA). Effect of various experimental parameters such as light intensity, solvents, ligands, the volume of the reaction solution, size of the Si-wafers, amount of CuBr 2 , and CuBr 2 /ligand ratio in kinetics, linear increase of polymer layer thickness, final thickness and profile of unmodified edges were investigated. The successful fabrication of hydrophilic polymer brushes is confirmed via Fourier transfer infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), profilometry and water contact angle. A linear thickness increase with time up to at least 300 nm was achieved, compared to polymethacrylate layers with thickness up to approximately 100 nm previously published by using photoATRP. The general applicability of the optimized conditions for SI-μL-CuPhotoATRP was further proved for two additional hydrophilic monomers, such as glycidyl methacrylate and 2-hydroxypropyl methacrylate. Furthermore, sequential homo and block copolymerization demonstrated the living character of fabrication conditions, permitting facile fabrication of well-controlled tetra block homo/copolymer brushes with a pyramid-like pattern on Si-wafer. Poly(2-hydroxyethyl methacrylate) (PHEMA) brushes-grown surfaces exhibit excellent antifouling properties and long-term structural stability. The facile, affordable, and environmentally friendly SI-μL-CuPhotoATRP approach provides avenues for various surface modifications, such as biomedical, soft robotic, and coating applications. [ABSTRACT FROM AUTHOR]

A monomer of the AB-type and a bifunctional comonomer of the AA-type containing two 2-oxazoline rings and a biphenyl structural unit were prepared from the corresponding carboxylic acids via their esterification and subsequent amidation with an aminoalcohol. The cyclization of an amide to 2-oxazoline structure was achieved by treatment with thionyl chloride followed by liberation of the free base with sodium hydrocarbonate in an aqueous solution. The prepared monomers were used for the polyaddition polymerization of the AB-type monomer having a 2-oxazoline and phenol group bound on adjacent rings of the biphenyl structure in solution. The monomer of the AA-type was used for AA+BB-type polyaddition reactions with aliphatic dicarboxylic acids. Both types of polymerizations have been performed in melt and in solution. The structures of the polymers were determined, and the thermal properties of the polymers were evaluated. Liquid-crystalline (LC) structures of the prepared polymers were observed by DSC measurements and optical microscopy. The polyaddition reactions of the monomers containing a 2-oxazoline ring and a biphenyl unit represent a new efficient way for the preparation of a biphenyl unit containing poly(ether amide)s and poly(ester amide)s. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

[Display omitted] • A study on lipase-producing yeast Sporidiobolus metaroseus. • The Extracellular Enzymatic Mixture (EEM) of yeast was extracted. • The EEM was characterized through biochemical analyses. • The EEM combined with various gels was applied for removing an overpainting. • The effectiveness of the enzymatic application was evaluated by ATR-FTIR. Biocleaning of cultural heritage items is mainly performed using living microorganisms. Approaches utilizing the enzymes of isolated microorganisms have not been frequently investigated. To find an enzymatic alternative for the removal of an oil-based overpainting, we focused on the characterization and use of a yeast Extracellular Enzymatic Mixture (EEM). A historical silk yeast was selected for its lipolytic properties and its EEM was extracted after cultivation on a medium supplemented with linseed oil. The EEM protein content was visualized by SDS-PAGE, its concentration assessed by fluorimeter and the enzymatic activity evaluated by p-NPP spectrophotometric lipase assay. The yeast growth was suppressed by adding diverse metal ions (Cd, Zn, Cr and Cu) in Reasoner's 2A (R2A) broth, while the quantity and activity of EEM were affected by adding Fe and Pb. Various delivery systems (agar-agar, tylose and klucel G) alone or in a combination with EEM were assayed on the historical painting surface. The colorimetric measurements and the ATR-FTIR analysis indicated that the combinations tylose-EEM and klucel G-EEM can be easily and effectively applied as biocleaning procedures to remove oil-based overpainting from fragile and valuable historical painting surfaces. [ABSTRACT FROM AUTHOR]

Commercial metallocene ethylene–octene random copolymer, Resinex PE RXP 1502 (RXP), was grafted with acrylic or crotonic acid in the solution and in the melt to increase the RXP's polarity and adhesion to cellulose-based substrates. Acrylic or crotonic acids were grafted on the RXP macromolecules which were activated with an oxygen–ozone mixture. The formed graft copolymer was tested as additive to a hot melt adhesive (HMA) improving adhesive properties. The most effective procedure was to graft RXP with acrylic acid in the melt, while grafting activated RXP in a toluene solution was less efficient. The melt grafting efficiency is high and varies between 0.77 and 0.97. The RXP polarity after grafting increases significantly, as there is a 15% decrease in the water contact angle and an increase in the surface energy and its polar component by 1.1–1.7 times as compared to the virgin RXP. The heat-fail temperature resistance in peel of RXP grafted with acrylic and/or crotonic acid increased by more than 10°C, while the heat-fail temperatures of adhesive joints in shear tests were similar. The adhesive joint peel strength increased 1.2 times. The cardboard–HMAs based on virgin RXP adhesive joint peel tests exhibit adhesive failure, whereas the cardboard–HMAs containing grafted RXP joints show cohesive failure. [ABSTRACT FROM AUTHOR]

An investigation was made of wood of the species oak (Quercus petraea), beech (Fagus sylvatica L.), maple (Acer pseudoplatanus) and ash (Fraxinus excelsior) pre-treated using radio-frequency (RF) plasma in air at reduced pressure. Physical and chemical changes for all of the wood species were determined using measurements of water contact angles and FTIR-ATR spectroscopy. The results confirmed an increase in the wood’s hydrophilicity/polarity in all cases, caused by an increase in –OH group concentration due to irradiation by RF plasma. The content of oxygen-containing functional groups after treatment by RF plasma significantly increased, and the water contact angles were diminished. FTIR-ATR spectroscopy confirmed that RF plasma modification of the surfaces of all investigated wood samples led to certain changes, which were also dependent on the time of plasma exposure. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report of employing the electron beam irradiation for preparation of poly(2-oxazoline)-based hydrogel coatings. • Applied method is independent on surface material (Si wafer, PS plate). • Grafting and crosslinking are driven by amount of double bonds essential for the formation of covalent bonds. • Presence of the hydrogel layer decreases cell adhesion to a negligible value. • The stiffness increases with the degree of crosslinking which denotes the possibility of adjusting the required stiffness by proper selection of the experimental parameters. Uncontrolled accumulation of proteins and cells on implantable materials often leads to failure of their performance in vivo. The idea presented in this paper is the use of electron beam irradiation as a widely applicable, cost-effective, and defined method to produce non-biofouling hydrogel coatings to improve the biocompatibility and in vivo performance of implantable materials. Statistical copolymers poly[2-methyl-2-oxazoline-co-2-(3-butenyl)-2-oxazoline]s were deposited on different substrates and irradiated with beta radiation of different radiation doses (2–100 kGy). In the bulk state experiments, we found that the higher content of crosslinkable 3-butenyl units and a higher radiation dose resulted in more efficient crosslinking. Similarly, the irradiation of coatings demonstrated the high impact of the concentration of 3-butenyl units on crosslinking efficiency. Accordingly, the concentration of crosslinkable double bonds in the copolymer is crucial for the stability and homogeneity of the formed hydrogel layer. Stable and uniform hydrogel layers with thicknesses in the micrometer range were prepared from a 5 wt% copolymer solution. Depending on the preparation conditions, the hydrogel layers showed excellent non-biofouling properties with a low number of adherent cells. In addition, stiffness was dependent on the degree of crosslinking, and can thus be tailored for specific application in living tissue. [ABSTRACT FROM AUTHOR]

Three biodegradable plastics materials, namely pure poly( l -lactide) (PLA), PLA with plasticizer triacetine (TAC) and the mixture PLA/polyhydroxybutyrate (PHB) and TAC were investigated concerning changes of physical properties due to biodegradation in compost at 58 °C up to 16 days. With rising time of degradation in compost, both number and weight molecular masses were decreasing progressively, but only marginal change of the polydispersity index was observed which indicates that biodegradation is not random process. FTIR spectroscopy revealed that in spite of the extensive decrease of molecular weight, no substantial change in chemical composition was found. The most significant modification of the spectra consisted in an appearing of the broad band in region 3100–3300 cm −1 , which was assigned to a formation of biofilm on the sample surfaces. This effect appeared for all three materials, however, it was much more pronounced for samples containing also triacetine. Measurement of changes in crystalline portion confirmed that amorphous phase degrades substantially faster compared to crystalline part. The plasticizer triacetine is disappearing also rather fast from the sample resulting besides other effect also in a temporary increase of Tg, which at the beginning grows almost to the value typical for PLA without plasticizer but later the Tg is decreasing due to substantial changes in molecular weight. Generally during composting, the samples keep shape for up to 8 days, after that time the material disintegrates to rough powder. [ABSTRACT FROM AUTHOR]

Boron-doped SiC thin films were deposited on N-type Si(100) substrates at various deposition conditions by means of HWCVD technology using silane (SiH4), methane (CH4), hydrogen(H2), diborane (B2H6, 5vol.% in H2) and argon (Ar) gas as precursors. Elements concentration was determined by RBS and ERD method. Chemical compositions were analyzed by FTIR and Raman spectroscopy. Solar cell structure with top grid Al electrode was prepared to investigate the photovoltaic response and to gain insight about the quality of films and their suitability for photovoltaic applications. Comparison of open-circuit voltage (VOC), short-circuit current (Isc), fill factor (FF) and efficiency (Ef) was discussed. [ABSTRACT FROM AUTHOR]

Low-temperature plasma was used to improve the surface and adhesive properties of wood. The pre-treatment of wood surfaces using radio-frequency (RF) discharge plasma is attractive for various wood applications, mainly because of the high efficiency and low production cost of the process. In addition, a significant increase in the polar component of the wood surface energy, which is associated with the presence of acid–base interactions (electron donor–acceptor bonds), after modification by RF discharge plasma was identified. The treatment of wood by RF plasma exhibited an aging effect, with the modified surface never recovering its initial hydrophobic state. Indeed, the enhancement of the wettability of wood is necessary for promoting better adhesion with water-based adhesives and coatings, which is currently the subject of ongoing study. [ABSTRACT FROM AUTHOR]

Long-range effect (LRE), which is known for ion-implanted crystals of diamond, metals and semiconductors, has also been observed in ion-implanted polymers. The effect is that a change in the physical characteristics of the material is observed far beyond the region of ion penetration into the sample. The present study was performed with polymethylmethacrylate (PMMA) implanted with 40 keV B+ ions with different fluences of ions and current density less than 2 μA cm−2. The samples were studied by nanoindentation technique with an ultra-nanohardness tester (UNHT), positron annihilation lifetime spectroscopy (PALS), and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). It was found that the changes of nanohardness induced by ion irradiation are observed up to a distance of about 1300 nm from the surface. This distance is much larger the size of implanted region that is of about 400 nm. The obtained PALS and ATR-FTIR results also testify that the microstructural changes occur far beyond the implanted layer of polymer. It is assumed that the observed effect is explained by the occurrence of internal mechanical stresses due to polymer carbonization in the implanted region of the sample. • Long-range effect (LRE) is found for ion-implanted polymers. • The effect is that a change in the physical characteristics of the material is far beyond of ion penetration into the sample. • The effect is confirmed by using independent methods – nanoindentation, positron annihilation and infrared spectroscopy. • In all cases of ionic treatment of polymers, the LRE must be taken into account. [ABSTRACT FROM AUTHOR]

A modified in situ polymerization microencapsulation procedure for the preparation of microcapsules with paraffin wax cores (43 wt.%) and melamine–formaldehyde resin shells having a uniform size distribution and a spherical shape with average diameters of approximately 15 μm was developed. The high-density polyethylene/microcapsule blends were prepared via two routes. In the first case, the dry high-density polyethylene powder covered by microcapsules was simply hot pressed, whereas, in the second case, the dry high density polyethylene/capsule powder was first blended in the molten state to obtain better homogeneity before hot pressing. It was observed that both systems behave qualitatively the same with comparable mechanical properties and thermal behavior. The thermal stability of high-density polyethylene/microcapsule blends characterized by thermogravimetry is significantly lower than that of neat high-density polyethylene. The selected characteristic temperatures of degradation decreased by more than 200 °C compared with the related temperatures for neat high-density polyethylene. An analysis based on Differential Scanning Calorimetry revealed separated melting and crystallization behavior of wax within the capsules and high density polyethylene in the blends. The enthalpies of melting and crystallization are proportional to the amount of individual components in the material. The capsules have a strong plasticizing effect on the high density polyethylene, resulting in a significant decrease in the melting and crystallization temperatures. The plasticizing effect was also confirmed by measurements of the tensile mechanical properties and rheological behavior. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) and nitrogen-doped silicon carbide (SiC(N)) films were deposited on p-type Si(100) substrates at various deposition conditions by means of plasma-enhanced chemical vapor deposition (PECVD) technology using silane (SiH4), methane (CH4), and ammonia (NH3) gas as precursors. The concentration of elements in the films was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical method simultaneously. Chemical composition was analyzed by Fourier transform infrared spectroscopy (FT-IR). The films contain a small amount of oxygen. IR results showed the presence of SiC, SiN, SiH, CH, CN, NH, and SiO bonds. The current-voltage ( I- V) characteristics of samples before and after neutron irradiation were measured. The measured current increases after irradiation with neutrons. [ABSTRACT FROM AUTHOR]

Wasted synthetic fabrics are a type of textile waste source; the reuse of them brings environmental protection and turns waste into a valuable material. In this work, the used nylon (polyamide) stockings were transmuted into a fine fibrous membrane via an electrospinning process. In addition, the safety antibacterial agent, monoacylglycerol (MAG), was incorporated into a recycled fibrous membrane. The results revealed that the neat, recycled polyamide (rPA) fibers with a hydrophobic surface could be converted into hydrophilic fibers by blending various amounts of MAG with rPA solution prior to electrospinning. The filtration efficiency and air/water vapor permeability of the two types of produced membranes, neat rPA, and rPA/MAG, were tested. Their filtration efficiency (E100) was more than 92% and 96%, respectively. The membranes were classified according to Standard EN1822, and therefore, the membranes rPA and rPA/MAG were assigned to the classes E10 and E11, respectively. The air permeability was not affected by the addition of MAG, and water vapor permeability was slightly enhanced. Based on the obtained data, prepared rPA/MAG fibrous membranes can be evaluated as antifouling against both tested bacterial strains and antimicrobial against S. aureus. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous silicon carbide (a-SiC) is an excellent alternative passivation layer material for silicon solar cells especially working in hard and space environment. Silicon carbide (SiC) and nitrogen-doped silicon carbide (SiC(N)) layers were deposited on P-type Si(100) substrates at various deposition conditions by means of plasma enhanced chemical vapor deposition (PECVD) technology using silane (SiH4) methane (CH4) and ammonium (NH3) gas as precursors. The concentration of elements in layers was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical method simultaneously. Chemical compositions were analyzed by Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Irradiation of samples by fast neutrons with fluence 1.4×1014 cm−2 was used. No significance effect on the IR spectra band features after neutron irradiation was observed. Intensity of Raman spectra band features was decreased after neutron irradiation. The measured currents after irradiation are greater (up to 100 times) than the current before irradiation for all samples. [Copyright &y& Elsevier]

Abstract: Low-density polyethylene (LDPE) belongs to commodity polymer materials applied in biomedical applications due to its favorable mechanical and chemical properties. The main disadvantage of LDPE in biomedical applications is low resistance to bacterial infections. An antibacterial modification of LDPE appears to be a solution to this problem. In this paper, the chitosan and chitosan/pectin multilayer was immobilized via polyacrylic acid (PAA) brushes grafted on the LDPE surface. The grafting was initiated by a low-temperature plasma treatment of the LDPE surface. Surface and adhesive properties of the samples prepared were investigated by surface analysis techniques. An antibacterial effect was confirmed by inhibition zone measurements of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The chitosan treatment of LDPE led to the highest and most clear inhibition zones (35mm2 for E. coli and 275mm2 for S. aureus). [Copyright &y& Elsevier]

Polyethylene (PE) is one of the most widely used polymers in many industrial applications. Biomedical uses seem to be attractive, with increasing interest. However, PE it prone to infections and its additional surface treatment is indispensable. An increase in resistance to infections can be achieved by treating PE surfaces with substances containing antibacterial groups such as triclosan (5-Chloro-2-(2,4-dichlorophenoxy)phenol) and chlorhexidine (1,1'-Hexamethylenebis[5-(4-chlorophenyl)biguanide]). This work has examined the impact of selected antibacterial substances immobilized on low-density polyethylene (LDPE) via polyacrylic acid (PAA) grafted on LDPE by low-temperature barrier discharge plasma. This LDPE surface treatment led to inhibition of Escherichia coli and Staphylococcus aureus adhesion; the first causes intestinal disease, peritonitis, mastitis, pneumonia, septicemia, the latter is the reason for wound and urinary tract infections. [ABSTRACT FROM AUTHOR]

From environmental aspects, the recovery of keratin waste is one of the important needs and therefore also one of the current topics of many research groups. Here, the keratin hydrolysate after basic hydrolysis was used as a filler in plasticized polylactic acid/poly(3-hydroxybutyrate) blend under loading in the range of 1–20 wt%. The composites were characterized by infrared spectroscopy, and the effect of keratin on changes in molar masses of matrices during processing was investigated using gel permeation chromatography (GPC). Thermal properties of the composites were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of keratin loading on the mechanical properties of composite was investigated by tensile test and dynamic mechanical thermal analysis. Hydrolytic degradation of matrices and composites was investigated by the determination of extractable product amounts, GPC, DSC and NMR. Finally, microbial growth and degradation were investigated. It was found that incorporation of keratin in plasticized PLA/PHB blend provides material with good thermal and mechanical properties and improved degradation under common environmental conditions, indicating its possible application in agriculture and/or packaging. [ABSTRACT FROM AUTHOR]

Diclofenac sodium salt (DSS)-loaded electrospun nanofiber mats on the base of poly(ε-caprolactone) (PCL) were investigated as biocompatible nanofibrous mats for medical applications with the ability to inhibit bacterial infections. The paper presents the characteristics of fibrous mats made by electrospinning and determines the effect of medicament on the fiber morphology, chemical, mechanical and thermal properties, as well as wettability. PCL and DSS-loaded PCL nanofibrous mats were characterized using scanning electron microscopy, transmission electron microscopy, attenuated total reflectance-Fourier transform infrared spectrometry, dynamic mechanical analysis, and contact angle measurements. Electron paramagnetic resonance measurements confirmed the lifetime of DSS before and after application of high voltage during the electrospinning process. In vitro biocompatibility was studied, and it was proved to be of good viability with ~92% of the diploid human cells culture line composed of lung fibroblast (MRC 5) after 48 h of incubation. Moreover, the significant activity of DSS-loaded nanofibers against cancer cells, Ca Ski and HeLa, was established as well. It was shown that 12.5% (m/V) is the minimal concentration for antibacterial activity when more than 99% of Escherichia coli (Gram-negative) and 99% of Staphylococcus aureus (Gram-positive) have been exterminated. [ABSTRACT FROM AUTHOR]

Bacterial infection and their resistance to known antibiotics delays wound healing. In this study, nanochitosan dots (nChiD) produced by gamma irradiation have been encapsulated in bacterial cellulose (BC) polymer matrix to study the antibacterial potentials of these nanocomposites and their possible usage in wound healing treatment (scratch assay). Detailed analyses show that nChiDs have disc-like shape and average diameter in the range of 40 to 60 nm depending of the applied dose. All nChiDs as well as BC-nChiD nanocomposites emit green photoluminescence independently on the excitation wavelengths. The new designed nanocomposites do not have a cytotoxic effect; antioxidant analysis shows their moderate radical scavenging activity whereas antibacterial properties show significant growth inhibition of strains mostly found in difficult-to-heal wounds. The obtained results confirm that new designed BC-nChiD nanocomposites might be potential agent in wound healing treatment. Unlabelled Image • New innovative approach for wound healing treatment • Photoactive nanochitosan dots produced by gamma irradiation • Encapsulation of nanochitosan dots in bacterial cellulose • Nanochitosan dots/bacterial cellulose nanocomposite as moderate antioxidant agent • Nanochitosan dots/bacterial cellulose nanocomposite as strong bactericidal agent [ABSTRACT FROM AUTHOR]

• Very thin nanostructured carbon films contained C, n and a small amount of o and h. • Film morphology differed depending on the deposition parameters and substrate type. • Thin carbon films contained amorphous, graphite and nanocrystalline diamond phases. • Films prepared at 800 °C showed best photo-induced electron emission properties. • Photocathodes on sapphire substrate exhibited better results than on quartz substrate. Very thin N-doped nanostructured carbon films were deposited on quartz and sapphire substrate by radio-frequency reactive magnetron sputtering using carbon target and gas mixture of Ar and N 2 or N 2 +H 2 reactive gasses. Rutherford backscattering spectroscopy and Elastic recoil detection analytical methods determined the concentration of elements in the films. Scanning electron microscopy was used to investigate the surface morphology of nanostructured very thin carbon films. Raman spectroscopy was used for the determination of chemical structural properties of the thin nanostructured carbon films. Pulsed laser induced electron emission method was used for the study of photoelectron emission properties of nanostructured carbon films. Measured bunch charge results of fabricated transmission photocathodes showed better photoelectron emission properties of very thin nanostructured carbon films prepared on sapphire substrates. Effects of substrate and technology of very thin nanostructured carbon films on the properties of photo-induced electron emitters as backside illuminated transmission photocathode are discussed. [ABSTRACT FROM AUTHOR]

Silk fibroin is a biocompatible, non-toxic, mechanically robust protein, and it is commonly used and studied as a material for biomedical applications. Silk fibroin also gained particular interest as a drug carrier vehicle, and numerous silk formats have been investigated for this purpose. Herein, we have prepared electrospun nanofibers from pure silk fibroin and blended silk fibroin/casein, followed by the incorporation of an anti-inflammatory drug, diclofenac. Casein serves as an excipient in pharmaceutical products and has a positive effect on the gradual release of drugs. The characteristics of the investigated composites were estimated by scanning electron microscope, transmission electron microscope, thermogravimetric analysis, and a lifetime of diclofenac by electron paramagnetic resonance analysis. The cumulative release in vitro of diclofenac sodium salt, together with the antiproliferative effect of diclofenac sodium salt-loaded silk nanofibers against the growth of two cancer cell lines, are presented and discussed. [ABSTRACT FROM AUTHOR]

The dynamics of n-propanol confined in regular MCM-41matrix with the pore size Dpore = 40 Å, under various matrix conditioning and sample confining conditions, using broadband dielectric spectroscopy (BDS), is reported. First, various drying procedures with the capacitor filling under air or N2 influence the BDS spectra of the empty MCM-41 and the confined n-PrOH/MCM-41 systems, but have a little effect on the maximum relaxation time of the main process. Finally, various filling factors of n-PrOHmedium in the optimally treated MCM-41system lead to unimodal or bimodal spectra interpreted in terms of the two distinct dynamic phases in the confined states. [ABSTRACT FROM AUTHOR]

Photoactive materials called photosensitizers can be used for treatment of different types of cancer in combination with light source. In this paper, we have investigated pro-oxidant and antioxidant potentials of four graphene based nanomaterials (graphene oxide-GO, graphene quantum dots-GQDs, carbon quantum dots-CQDs and N-doped carbon quantum dots-N-CQDs) depending on the presence/absence of visible light source. Structural and optical properties of these materials and their potentials for reactive oxygen species generation/quenching are investigated by applying different microscopy and spectroscopy techniques (transmission electron microscopy, FTIR, UV–Vis, photoluminescence, electron paramagnetic resonance). Results show that all types of quantum dots has pro-oxidant and antioxidant potentials whereas GO demonstrated only moderate antioxidant effect. The best free radical scavenger is CQDs sample in the absence of light. CQDs are the best singlet oxygen generator under blue light irradiation as well. To check photo-cytotoxicity of these materials, photo-cytotoxic concentrations of the GO, GQDs, CQDs and N-CQDs were determined for three cellular lines: human rhabdomyosarcoma (RD), cell line derived from human cervix carcinoma Hep2c (HeLa) and fibroblast cell line from murine (L2OB). Cytotoxicity test has indicated that all samples are much less photocytotoxic than cis -diamminedichloroplatinum (cis -DPP). The production method and doping of quantum dots affect the photodynamic activity of tested samples very much. Unlabelled Image • Graphene oxide size and structure materials. • Crossover between pro-oxidant and antioxidant activities. • Fullerene like structure affects ROS generation/quenching. • Blue light dependent cytotoxicity toward cancer cells. [ABSTRACT FROM AUTHOR]