Hybrid Graphenene Oxide/Cellulose Nanofillers to Enhance Mechanical and Barrier Properties of Chitosan-Based Composites.

Chitosan-based hybrid nanocomposites, containing cellulose nanocrystals (CNCs), graphene oxide (GO), and borate as crosslinking agents, were successfully prepared by solution-casting technique. The synergistic effect of the two fillers, and the role of the cross-linker, in enhancing the structural and functional properties of the chitosan polymer, was investigated. XPS results confirm the chemical interaction between borate ions and hydroxyl groups of chitosan, GO, and CNCs. The morphological characterization shows that the GO sheets are oriented along the casting surface, whereas the CNC particles are homogenously distributed in the sample. Results of tensile tests reveal that the presence of graphene oxide enhances the elastic modulus, tensile strength, elongation at break, and toughness of chitosan, while cellulose and borate induce an increase in the elastic modulus and stress at the yield point. In particular, the borate-crosslinked chitosan-based sample containing 0.5 wt% of GO and 0.5 wt% of CNCs shows an elongation at a break value of 30.2% and a toughness value of 988 J*m-3 which are improved by 124% and 216%, respectively, compared with the pristine chitosan. Moreover, the water permeability results show that the presence of graphene oxide slightly increases the water barrier properties, whereas the borate and cellulose nanocrystals significantly reduce the water vapor permeability of the polymer by about 50%. Thus, by modulating the content of the two reinforcing fillers, it is possible to obtain chitosan-based nanocomposites with enhanced mechanical and water barrier properties which can be potentially used in various applications such as food and electronic packaging.

MWCNT/rGO/natural rubber latex dispersions for innovative, piezo-resistive and cement-based composite sensors.

The present study is focused on the development and characterization of innovative cementitious-based composite sensors. In particular, multifunctional cement mortars with enhanced piezoresistive properties are realized by exploiting the concept of confinement of Multiwall Carbon Nanotubes (MWCNTs) and reduced Graphene Oxide (rGO) in a three-dimensional percolated network through the use of a natural-rubber latex aqueous dispersion. The manufactured cement-based composites were characterized by means of Inelastic Neutron Scattering to assess the hydration reactions and the interactions between natural rubber and the hydrated-cement phases and by Scanning Electron Microscopy and X-Ray diffraction to evaluate the morphological and mineralogical structure, respectively. Piezo-resistive properties to assess electro-mechanical behavior in strain condition are also measured. The results show that the presence of natural rubber latex allows to obtain a three-dimensional rGO/MWCNTs segregate structure which catalyzes the formation of hydrated phases of the cement and increases the piezo-resistive sensitivity of mortar composites, representing a reliable approach in developing innovative mortar-based piezoresistive strain sensors.

Effect of carbonaceous fillers on adsorption behavior of multifunctional diatomite-based foams for wastewater treatment.

Nowadays the study of the potential applications of multifunctional materials for environmental remediation is one of the main goals of the materials engineering. Multifunctional porous materials, MPMs, incorporate, all in once, different and multiple functionalities that make them suitable for several uses and can satisfy many purposes at the same time. Multifunctional diatomite-based foams with a hierarchical porosity, already produced and characterized to be applied in building as well as aerospace sectors, are proposed as adsorbents for inorganic and organic pollutants removal from wastewaters. Then, the effect of the addition of different carbonaceous nanofillers (graphite, graphene and graphene oxide) on the water purification efficiency of the adsorbent was evaluated. Firstly, pristine MPM showed the best performance in adsorbing Indigo Carmine due to its intrinsic chemism and hierarchical porosity (at macro-, micro- and nano-level), but it is not the best with respect to the Cd2+ adsorption, if compared with the nanocomposites. Among the nanocomposite products, both graphene- and graphene oxide-MPM samples showed a significantly improved adsorption capacity towards Cd2+. This behavior is due to the synergistic effect of the finer morphology, higher available foam surface, and the highly exfoliated fillers, graphene and graphene oxide, which permit a better dispersion into the matrix.

Process strategy to fabricate a hierarchical porosity gradient in diatomite-based foams by 3D printing.

Motivated by the hierarchical micro and nanoscale features in terms of porosity of diatomite, the production of ceramic-graded porous foams with tailored porosity, obtained by using it as raw material, has been proposed. The main challenge during the foam-production process has been the preservation of diatomite nanometric porosity and the addition of other levels of hierarchical porosity. The coupled use of two techniques of direct foaming (chemical and mechanical), combined with the use of 3D printing inverse replica method, assured the achievement of porosity of, respectively, microscopic and macroscopic dimensions. Optical and scanning electron microscopies have been performed for an in-depth characterization of the final microstructure. XRD analysis has been carried out to check the influence of sacrificial templates on the matrix mineralogical composition. The porosity of the diatomite-based foams has been investigated by means of nitrogen-adsorption analysis and mercury-intrusion porosimetry. The experimental tests confirmed the presence of different porous architectures ranging over several orders of magnitudes, giving rise to complex systems, characterized by hierarchical levels of porosity. The presence of porosity of graded dimensions affects the final mechanical performances of the macroporous diatomite-based foams, while their mineralogical composition does not result to be affected by the addition of templates.

Tuning of polyurethane foam mechanical and thermal properties using ball-milled cellulose.

Cystalline-Cc and ultra-milled Amorphous-Ca cellulose were used as reactive filler to tune the performances of composite polyurethane-cellulose-foams, PUC. The effect of Cc and Ca on chemo-physical and mechanical properties of PUC was analysed through FTIR, morphological analysis, thermal conductivity and compression measurements. FTIR results show that, both Cc and Ca react with isocyanate through the OH functional groups contributing to the formation of a tough cellulose-polyurethane network. Morphological observations show that the addition of both Cc and Ca induces a decrease of average cell-size compared to the pristine-PU, thus confirming that they act as nucleating agent. In addition, the better dispersion of the Ca in the polyol, with respect to Cc induces, a finer cell leading to a reduction of the thermal conductivity around 33 % (for the composite loaded with 20 %wt-Ca) with respect to pristine-PU. Finally, the addition of Ca highly reactive modifies the mechanical behaviour from rigid-brittle to semi-rigid.

Optimization of dye adsorption capacity and mechanical strength of chitosan aerogels through crosslinking strategy and graphene oxide addition.

Chitosan (CS) aerogels were prepared by freeze-drying as potential adsorbents for water purification, and the effect of the strategy of crosslinking was investigated by varying the amount of crosslinker (glutaraldehyde) and the sequence of steps for the preparation of the aerogel. Two procedures were compared, in which the crosslinking step was carried out before or after the freeze-drying of the starting CS solution. When crosslinking was postponed after the freeze-drying step, the adsorption capacity towards an anionic dye, such as indigo carmine, considerably increased (up to +45%), reaching values as high as 534.4 ± 30.5 mg g-1. The same crosslinking strategy ensured a comparable improvement also in nanocomposite aerogels containing graphene oxide (GO), which was added to enhance the mechanical strength and provide adsorption capacity towards cationic dyes. Besides possessing good mechanical strength (compressive modulus higher than 1 MPa), the CS/GO aerogels were able to bind also cationic pollutants such as methylene blue. The maximum uptake capacity increased from 4.3 ± 1.6 to 168.6 ± 9.6 mg of cationic dye adsorbed per gram of adsorbent with respect to pristine CS aerogels.

Characterization of sustainable polyhydroxyls, produced from bio-based feedstock, and polyurethane and copolymer urethane-amide foams.

This manuscript presents data related to the research article entitled "Synthesis and characterization of sustainable polyurethane foams based on polyhydroxyls with different terminal groups" (DOI: 10.1016/j.polymer.2018.06.077) [1]. We provide Supplementary data on the chemical properties, in terms of FTIR characterization, of polyhydroxyls produced starting from bio-based feedstock (biosuccinic acid and 1,4 butandiol) and thermal properties (glass transition temperature-Tg and thermal degradation behavior) of polyurethane and copolymer urethane-amide foams manufactured from the aforementioned polyhydroxyls. The FTIR characterization elucidates the chemical structure of polyhydroxyls and allows to make some hypothesis on their reaction routes with the isocyanate molecules. The thermal characterization revealed that the addition of bio-based polyhydroxyls to the sample formulations improves both the glass transition and degradation temperature of the foams. These foamed products exhibit potential performances to be applied as a substitute for conventional polyurethane foams.

MMT-supported Ag nanoparticles for chitosan nanocomposites: structural properties and antibacterial activity.

Multifunctional bionanocomposites have been prepared by loading chitosan matrix with silver-montmorillonite antimicrobial nanoparticles obtained by replacing Na(+) ions of natural montmorillonite with silver ions. This filler has been chosen for its twofold advantage to serve as silver supporting material and to confer new and better performance to the obtained material. It has been proved that the achievement of the intercalation of chitosan into the silicate galleries of montomorillonite as well as the interaction between chitosan and Ag ions and silver particles lead to an enhancement of the thermal stability, to an improvement of mechanical strengths and to a reduction of the liquid water uptake of the obtained bionanocomposites. Results also show that silver ions are released in a steady and prolonged manner providing, after 24 h, a significant reduction in the microbial growth of Pseudomonas spp.

Treatment and recycling of asbestos-cement containing waste.

The remediation of industrial buildings covered with asbestos-cement roofs is one of the most important issues in asbestos risk management. The relevant Italian Directives call for the above waste to be treated prior to disposal on landfill. Processes able to eliminate the hazard of these wastes are very attractive because the treated products can be recycled as mineral components in building materials. In this work, asbestos-cement waste is milled by means of a high energy ring mill for up to 4h. The very fine powders obtained at all milling times are characterized to check the mineralogical and morphological transformation of the asbestos phases. Specifically, after 120 min of milling, the disappearance of the chrysotile OH stretching modes at 3690 cm(-1), of the main crystalline chrysotile peaks and of the fibrous phase are detected by means of infrared spectroscopy and X-ray diffraction and scanning electron microscopy analyses, respectively. The hydraulic behavior of the milled powders in presence of lime is also tested at different times. The results of thermal analyses show that the endothermic effects associated to the neo-formed binding phases significantly increase with curing time. Furthermore, the technological efficacy of the recycling process is evaluated by preparing and testing hydraulic lime and milled powder-based mortars. The complete test set gives good results in terms of the hydration kinetics and mechanical properties of the building materials studied. In fact, values of reacted lime around 40% and values of compressive strength in the range of 2.17 and 2.29 MPa, are measured.

Active systems based on silver-montmorillonite nanoparticles embedded into bio-based polymer matrices for packaging applications.

Silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles were obtained by allowing silver ions from nitrate solutions to replace the Na(+) of natural montmorillonite and to be reduced by thermal treatment. The Ag-MMT nanoparticles were embedded in agar, zein, and poly(ε-caprolactone) polymer matrices. These nanocomposites were tested in vitro with a three-strain cocktail of Pseudomonas spp. to assess antimicrobial effectiveness. The results indicate that Ag-MMT nanoparticles embedded into agar may have antimicrobial activity against selected spoilage microorganisms. No antimicrobial effects were recorded with active zein and poly(ε-caprolactone). The water content of the polymeric matrix was the key parameter associated with antimicrobial effectiveness of this active system intended for food packaging applications.

Chemical and toxic evaluation of a biological treatment for olive-oil mill wastewater using commercial microbial formulations.

Olive-oil-mill wastewater (OMW) has significant polluting properties due to its high levels of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and phenols. In the present study, different commercial bacterial formulations were used in the biological treatment of OMW. COD and toxicity testing using primary consumers of the aquatic food chain (the rotifer Brachionus calyciflorus and the crustacean Daphnia magna) were employed to evaluate abatement of the organic load and reduction of the toxic potential. In addition, the four most active formulations were tested mixed pair-wise on the basis of their unique characteristics in order to evaluate the improvement of treatment. The effect of treatment was assessed by measuring COD removal, reduction of total phenols, and decreased toxicity. The results obtained with the mixed formulations showed that the maximum removal of the organic load was about 85%, whereas phenols were reduced by about 67%. The toxicity for rotifers decreased by 43% and for crustaceans by about 83%.

The effects of salinomycin and roxarsone on the performance of broilers when included in the feed for four, five, or six weeks and infected with Eimeria species during the starter or grower phase of production.

The timing and magnitude of a coccidian infection, judged by the numbers of oocysts of Eimeria present in the litter, were affected by the duration of medication. In birds medicated for 6 wk and infected at 35 d of age, fewer oocysts were produced than in birds medicated for 4 or 5 wk whether infected at 18 or 35 d of age. Feed conversion at 6, 7, and 8 wk of birds infected at 18 d and medicated for 6 wk was less than that of birds medicated for 4 or 5 wk. Birds infected at 35 d and medicated for 6 wk had a lower feed conversion than birds medicated for 5 wk. Immunity to Eimeria tenella had developed by 8 wk in birds medicated for 4, 5, or 6 wk if infected at 18 d of age. Immunity did not develop in those birds medicated for 6 wk when infected at 35 d.

[Environmental quality of Volturno river with toxic and genotoxic findings]. / Stato di qualità ambientale del fiume Volturno integrato da indagini di tossicità e genotossicità.

In order to assess the environmental quality of Volturno river in Southern Italy, the Extended Biotic Index, chemical and microbiological parameters were determined in nine sampling points as provided for D. Lgs. 152/99. Furthermore, this study reported toxicity of surface waters and pore waters from sediments and genotoxicity of pore waters to improve the definition of the ecological condition of the investigated watercourse. Results showed that toxicity and genotoxicity testing contributed to assess environmental quality and pore waters are an useful tool to combine investigations.

Environmental and technological effectiveness of a process for the stabilization of a galvanic sludge.

A binding matrix containing calcium silicate beta-2CaO.SiO(2) and sulphoaluminate 4CaO.3Al(2)O(3).SO(3), and CaSO(4) that gives calcium silicate and trisulphoaluminate hydrates upon hydration has been used for the stabilization of a solid waste from a galvanic treatment process. The waste is to be disposed of in a hazardous wastes landfill to prevent the risk of cadmium, chromium and nickel release. Anhydrous calcium silicate and sulphoaluminate of the binder have been synthesized using a mixture containing powdered tuff in addition to bauxite and calcium carbonate and sulphate. Powdered tuff is quarry dust and is, as such, a true residue. Experiments have been carried out with mixtures containing up to 60% waste and have been addressed towards the environmental and technological assessment of the effectiveness of the stabilization process. Specifically, the study has been carried out taking into account requirements from three different points of view, that is the influence of the waste on the hydration process and on the technological properties of the stabilized products, the leaching behavior under some selected conditions and the effect of the leaching medium on the binding matrix in the stabilized system.

The biotechnology for the removal of specific pollutants.

In the last century, thanks to the development of molecular trials such as those involving genetic modification, biotechnologies have asserted themselves in diversified sectors and their evolution has been rapid, resulting in an enormous impact on the productive sector, on the quality of life, and on the consequences that their employment can have for man and, above all, for the environment. In particular, the application of biotechnologies in the sector concerned with the management and disposal of dangerous and non dangerous wastes, as well as in the sector concerned with the remediation of grounds contaminated by organic and inorganic pollutants, has led to the development of systems and processes that represent a valid and consolidated methodology for environmental improvement. This paper reviews the various different ways in which biotechnologies have been employed in the above sectors, citing the conditions necessary for their successful application, and stressing the great potential that these methodologies have, if optimised by means of further research, for solving environmental problems.

Response to divergent selection for early growth of chickens fed a diet deficient in selenium.

Three generations of divergent selection for 21-day growth response to a diet deficient in selenium (-Se) were bred using a meat-type chicken. The Athens-Canadian Randombred (AC) population of chickens served as the base population for this study. Mass selection was used to establish a -Se refractory line (SDR) and a -Se susceptible line (SDS). A genetic control line was maintained during the selection process to facilitate evaluation of the responses of the selected lines. The SDR males and females had an average of 17% increase in weight gain at 21 days of age when fed the -Se diet compared with the control line males and females fed the same diet for the three generations of selection. The SDS line had an average reduction in weight gain of 27% during the same period of selection. A difference of 25 g was observed between the mean body weights of SDR males and females and between the SDS males and females after one generation of selection. By the third generation of selection, the difference between SDR and SDS males had increased to 31 g, whereas the SDR and SDS females differed by 41 g. Early response to selection was asymmetrical because the response was greater in the SDS than in the SDR line. Response to selection, however, generally declined after the first generation. Realized heritability estimates for individual generations for this trait were variable (ranging from -.26 to .95), but cumulative estimates (.15 to .39) for growth through three generations were similar to those reported for chickens and quail.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence of a hereditary factor affecting the chick's response to uncomplicated selenium deficiency.

Experiments were conducted to determine whether a hereditary factor accounted for part of the variation observed in the growth responses of young chicks to uncomplicated selenium (Se) deficiency. Results showed that such a factor influenced the growth of chicks fed a Se-deficient diet. Those chicks most susceptible (SUS) to the growth depressing effects of Se-deficiency oxidized 14CH3-methionine to 14CO2 at a greater rate when fed the Se-deficient diet than did chicks that appeared refractory (REF) (i.e., grew at near normal rates) to Se-deficiency. When diets were supplemented with Se, both lines exhibited equivalent rates of 14CH3-methionine oxidation. The SUS chicks appeared to have lower levels of free homocystine and cystathionine in plasma compared to REF chicks or to Se-supplemented chicks of both lines. These results provide evidence for an impairment in sulfur-amino acid metabolism as the basis of the hereditary effect.