Development of phase morphology in immiscible poly(styrene‐co‐acrylonitrile)/poly(butylene terephthalate) nanoblends: Mechanical properties and effect of the compatibilizer

Nanoblends were obtained from poly(styrene‐co‐acrylonitrile) (SAN) as a matrix, and poly(butylene terephthalate) (PBT) was used as a nanodispersed phase. Compatibilized SAN/PBT blends were prepared by reactive extrusion, and the PBT concentrations ranged between 3 and 30 wt %. Nanoblends were obtained for up to 10 wt % PBT concentrations in the presence of the compatibilizer. With 20 and 30 wt % PBT, the extruded material presented a droplet dispersed phase. The same blends were subjected to an injection‐molding process, which provided a cocontinuous phase morphology. The influence of the concentration of the dispersed phase and the type of morphology on the mechanical behavior of tensile test, flexural test, impact test, and deflection temperature of the blends was analyzed. The results show an important reduction in the particle size of the dispersed phase, which was due to the presence of the compatibilizer. Furthermore, the type of morphology and an excess of compatibilizer exerted a stronger influence on the mechanical properties than the particle size of the dispersed phase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45030.     

Structural and dielectric spectroscopy studies of the M-type barium strontium hexaferrite alloys (Ba x Sr1? x Fe12O19)

The M-type barium hexaferrite Ba _x Sr_1−x Fe₁₂O₁₉ (where 0 < x < 1) alloys were prepared by a new ceramic procedure. The samples were studied using X-ray diffraction and Rietveld analysis, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, infrared and M?ssbauer spectroscopy. The X-ray analysis indicates that the all the samples present a hexagonal structure. The IR spectra showed three main absorption bands in range of 400–600 cm⁻¹ corresponding to SFO100 and BFO100. The M?ssbauer spectra showed a superposition of five subspectra associated with the five sites of the iron ion, which in the ferric state. The SEM studies showed that the hexaferrites presented grains that varied in the range of 260–305 nm. The dielectric properties: dielectric constant (ε′) and dielectric loss (tg δ) were measured at room temperature in the frequency range from 100 Hz to 40 MHz. The samples present a nonlinear behavior for the dielectric constant at 100 Hz, 1 kHz and 1 MHz. The dielectric constant is not following the linear mixing rule for the samples. The structural, dielectric and magnetic properties of the composite barium hexaferrite phases were discussed in view of applications as a material for permanent magnets, high density magnetic recording and microwave devices.     

Thorns and dermal denticles of skates Atlantoraja cyclophora and A. castelnaui: Microscopic features and functional implications

Some batoid species are covered with dermal denticles (or placoid scales) that occasionally develop into thorns. In sexually mature males, sharp teeth and alar thorns found on the apex of the lateral disc are used to hold the female during copulation. This study set out to analyze microscopic features of modified dermal denticles and thorns and to investigate sexual dimorphism in Atlantoraja cyclophora and A. castelnaui species. Skin samples collected from areas covered with thorns were fixed in 10% formaldehyde, processed and analyzed using scanning electron microscopy. Alar thorn morphology varied within species, while caudal thorn, rostral and caudal dermal denticle morphology varied within and between species. These structures play an important role in the protection and reproduction of the species studied and constitute important taxonomic information, given they are often the only elements preserved in archaeological sites and fossil records.     

Development and immunobiological evaluation of nanoparticles containing an immunodominant epitope of herpes simplex virus

Herpes simplex virus (HSV) 1 and 2 are viruses that infect individuals worldwide and for which there is no cure or vaccine available. The protective response against herpes is mostly mediated by CD8 T lymphocytes that respond to the immunodominant SSIEFARL epitope. However, there are some obstacles concerning the use of free SSIEFARL for vaccine or immunotherapy. The aim of this study was to evaluate the feasibility of nanoencapsulation of SSIEFARL and its immunostimulatory properties. Nano/SSIEFARL was produced by interfacial polymerization in methylmetacrylate, and the physico‐chemical properties, morphology and immunobiological parameters were evaluated. To evaluate the ex vivo capacity of Nano/SSIEFARL, we used splenocytes from HSV‐1‐infected mice to enhance the frequency of SSIEFARL‐specific CD8 T lymphocytes. The results indicate that Nano/SSIEFARL has a spherical shape, an average diameter of 352 ± 22 nm, the PDI was 0.361 ± 0.009 and is negatively charged (−26.30 ± 35). The stability at 4°C was 28 days. Also, Nano/SSIEFARL is not toxic for cells at low concentrations in vitro and it is taken up by JAWS II dendritic cells. No histopathological changes were observed in kidneys, liver and lymph nodes of animals treated with Nano/SSIEFARL. Nan/SSIEFARL increased the production of IL‐1β, TNF‐α and IL‐12 by the dendritic cells. Finally, Nano/SSIEFARL expanded the frequency of SSIEFARL‐specific CD8+T lymphocytes at the same rate as free SSIEFARL. In conclusion all data together indicate that SSIEFARL is suitable for nanoencapsulation, and the system produced presents some immunoadjuvant properties that can be used to improve the immune response against herpes.     

Production and Corrosion Resistance of Thermally Sprayed Fe-Based Amorphous Coatings from Mechanically Milled Feedstock Powders

Mechanically milled FeCrNbB feedstock powders from commercial precursors were used to produce amorphous coatings through two different industrial thermal-spraying techniques: high-velocity oxygen fuel (HVOF) and flame spraying. Microstructure, thermal behavior, and hardness of the coatings and their corrosion resistances in acidic and alkaline chloride-rich media were comparatively studied. HVOF process was effective to produce ~ 200-µm-thick highly amorphous coatings with hardness over than 700 HV_0.3 and low porosity (~ 5 pct). Flame-sprayed ~ 220-µm-thick coatings were nanocrystalline, composed of α-Fe, Fe₂B, FeNbB, and Fe₂O₃ phases and presented hardness of 564 HV_0.3 and ~ 10 pct porosity. Electrochemical measurements indicated that HVOF coatings exhibit higher corrosion resistance than flame-sprayed ones thanks to the higher amorphous content and lower porosity resulting from the former processing route. Electrochemical impedance spectroscopy results demonstrated that amorphous HVOF Fe₆₀Cr₈Nb₈B₂₄ (at. pct) coatings are interesting to protect mild steels such as the API 5L X80 against corrosion in chloride-rich environments.

     

Emission factors for gas-powered vehicles traveling through road tunnels in São Paulo, Brazil

The objective of this study was to improve the vehicular emissions inventory for the light- and heavy-duty fleet in the metropolitan area of S?o Paulo (MASP), Brazil. To that end, we measured vehicle emissions in road tunnels located in the MASP. On March 22-26, 2004 and May 04-07, 2004, respectively, CO, CO2, NOx, SO2, and volatile organic compounds (VOCs) emissions were measured in two tunnels: the Janio Quadros, which carries light-dutyvehicles; and the Maria Maluf, which carries light-duty vehicles and heavy-duty diesel trucks. Pollutant concentrations were measured inside the tunnels, and background pollutant concentrations were measured outside of the tunnels. The mean CO and NOx emission factors (in g km(-1)) were, respectively, 14.6 +/- 2.3 and 1.6 +/- 0.3 for light-duty vehicles, compared with 20.6 +/- 4.7 and 22.3 +/- 9.8 for heavy-duty vehicles. The total VOCs emission factor for the Maria Maluf tunnel was 1.4 +/- 1.3 g km(-1). The main VOCs classes identified were aromatic, alkane, and aldehyde compounds. For the heavy-duty fleet, NOx emission factors were approximately 14 times higher than those found for the light-duty fleet. This was attributed to the high levels of NOx emissions from diesel vehicles.     

Generalization of a lumped parameters model using fractional derivatives applied to rice hydration

This study presents a generalization of a lumped parameters model through the use of fractional derivatives of arbitrary order. The conventional model has an analytical solution in terms of exponential function. However, when applied to kinetic data on moisture absorption in rice grains, its performance was worse when compared to the proposed generalized model. The results were analyzed for four hydration temperatures. Despite the similarity of the mass transfer coefficients for both models, the proposed generalization provided a statistically significant improvement in prediction of moisture values in relation to time and process temperature.

Practical applications

The model proposed in this paper is applicable in describing the hydration kinetics of rice which is an important step in parboiling process, for instance. The simplicity of the analytical solution of the model and the improvement of its prediction capability makes the presented approach useful to project of equipment intended to process rice.