General mixed mode I/II fracture criterion for wood considering T-stress effects

A general mixed mode I/II fracture criterion applicable to orthotropic materials with arbitrary oriented cracks with respect to the orthotropy axes is presented. Wasted energy in fracture process zone is considered based on the calculated damage properties for an elastic solid containing random distributed micro-cracks. This new criterion includes the effects of T-stress as a significant term in fracture of some specimens. The correctness and applicability of this criterion has been investigated for some wood specimens. Very good agreement is obtained from verification of results with experimental data.     

Synthesis of undoped and Fe nanoparticles doped SnO<Subscript>2</Subscript> nanostructure: study of structural,optical and electrocatalytic properties

In this study, undoped and nano Fe doped SnO₂ nanostructures were synthesized by hydrothermal method. Characterization of the synthesized nanostructures was performed by X-ray diffraction and scanning electron microscopy. For investigation of optical properties, photo luminescence and UV–Vis spectrum were taken. The electrochemical response of the carbon paste electrode modified with synthesized nanostructures toward levodopa (L-Dopa) was studied. Cyclic voltammetry studies using prepared modified electrodes showed outstanding electrocatalytic properties towards electro-oxidation of L-Dopa and a significant reduction was observed in anodic over voltage compared to the bare electrode. Obtained results indicated the effective role of the employed dopant. Best response in terms of the current enhancement, overvoltage reduction, and reversibility improvement of the L-Dopa oxidation reaction under experimental conditions was obtained by modified electrode with Fe doped SnO₂ nanoparticles.     

A probe into the status quo of interfacial adhesion in the compatibilized ternary blends with core/shell droplets: Selective versus dictated compatibilization

A simple approach was applied to probe into the situation of interfacial adhesion in the compatibilized ternary polymer blends with core/shell morphology. The performance of compatibilization was discussed in terms of thermal, rheological, and mechanical properties analyses for blends prepared through different mixing strategies for which maleic anhydride‐grafted high‐density polyethylene (HDPE‐g‐MAH) could be localized at the interface of HDPE/poly(ethylene‐co‐vinyl alcohol) copolymer (EVOH) or HDPE/polyamide 6 (PA‐6) in their ternary blends. Two mixing strategies, one simultaneously (one‐step or selective) and two sequentially (two‐step or dictated), were performed, compared, and discussed. It was found that mixing policy (dictated or selective) significantly changes the interfacial adhesion, as signaled by variations in rheological and thermal properties. In the case of mechanical properties, facilitation of stress transfer across the matrix/shell/core interfaces was detected by calculation of semi‐experimental models' coefficients. It was found that one‐step mixing or selective localization of HDPE‐g‐MAH helps in accumulation of more compatibilizer molecules at the interface HDPE/EVOH or EVOH/PA‐6. By contrast, addition of compatibilizer to minor phase (masterbatch of EVOH and PA‐6) or to HDPE matrix alone in case of two‐step blending causes imperfect stress transfer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45503.     

Effect of α-Fe2O3 addition on the morphological,optical and decolorization properties of ZnO nanostructures

Visible light sensitive photocatalysts of Fe₂O₃/ZnO nanocomposites were prepared by a simple solid-state reaction method, using zinc acetate, α-Fe₂O₃ and sodium hydroxide at room temperature. The products were characterized by scanning electron microscopy, powder X-ray diffraction, N₂ adsorption–desorption measurement, UV–vis absorption, and photoluminescence spectroscopy and used for photodecolorization of Congo red. The characterization results showed that the morphology, crystallite size, BET surface area and optical absorption of the samples varied significantly with the Fe³⁺ to Zn²⁺ ratios. The nanocomposites show two absorption edges at ultraviolet and visible region. The optical band gap values of these nanocomposites were calculated to be about 3.98–3.81 eV and 2.88–2.98 eV, which show a red shift from that of pure ZnO. These red shifts are related to the formation of Fe s-levels below the conductive band edge of ZnO and effectively extend the absorption edge into the visible region. The growth mechanisms of the samples are proposed. These nanocomposites showed high decolorization ability in visible light with wavelength up to about 400 nm. Among the samples, Fe₂O₃/ZnO nanoflower (molar ratio of Fe³⁺ to Zn²⁺ is 1:100) exhibited higher decolorization efficiency than the other nanocomposites. It could be considered as a promising photocatalyst for dyes treatment.     

High-Stability Platinum Nano-Electrocatalyst Synthesized by Cyclic Voltammetry for Oxygen Reduction Reaction

Cyclic voltammetry as a simple electrochemical deposition method was developed in order to prepare a platinum nano-electrocatalyst for oxygen reduction reaction (ORR) in low-temperature fuel cell systems. The morphology of the prepared platinum was evaluated by scanning electron microscopy and energy dispersive x-ray analysis. The effects of platinum concentration in electrodeposition solution and scan numbers of cyclic voltammetry (scan rate: 50 m V s^?1, between 1.489 and ??0.311 versus reversible hydrogen electrode) on the performance of prepared electrocatalysts for ORR were studied. The fabricated electrodes were evaluated by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The results revealed that the optimum conditions for the preparation of electrocatalysts were 2E?3 M H₂PtCl₆ and 30 scan numbers. The optimized electrode showed high stability after 1200 cycles.     

Effects of post-packaging pasteurization process on microbial,chemical, and sensory qualities of ready-to-eat cured vacuum-packed Turkey breast

Ready-to-eat (RTE) cured vacuum-packed turkey breast was pasteurized (80°C, 5.5 min) and stored at 8°C (like supermarkets refrigerator temperature). After 42 days (current shelf life of this product), in control group (RTE cured vacuum-packed turkey breast), the number of mesophilic, anaerobic, lactic acid bacteria, mold and yeast, coliform, and psychrotrophic increased 5.82, 6.85, 5.85, 4.75, 1.49, and 5.57 log CFU/g, respectively. However, in the pasteurized samples, the number of mesophilic, anaerobic, and lactic acid bacteria increased 1.86, 2.12, and 2.28 log CFU/g, respectively, and mold and yeast, coliform, and psychrotrophic bacteria were under the detection limit. The effects of post-packaging pasteurization on the reduction of total mesophilic, anaerobic and lactic acid bacteria counts on Day 42 of storage was 7.04 ± 0.33, 4.73 ± 0.11, and 5.58 ± 0.11 log CFU/g, respectively. Sensory quality of treated samples was significantly better than the control's (p < .05). Post-packaging pasteurization (PPP) significantly inhibited the reduction in the pH and the increase in TVB-N, TBARS, titratable acidity, and drip loss (p < .05). This study shows the effectiveness of PPP on microbial, chemical, and sensory quality of cured vacuum-packed turkey breast during cold storage.     

Reduction of metastatic properties of BL6 melanoma cells expressing terminal fucose(alpha)1-2-galactose after alpha1,2-fucosyltransferase cDNA transfection

We reported previously that transfection of BL6 melanoma cells that do not express the alpha1,3-galactosyltransferase (alpha1,3GT) gene with the alpha1,3GT cDNA resulted in synthesis and expression of alpha-galactosyl epitopes (Gal(alpha)1-3Gal(beta)1-4GlcNAc-R) and an impairment of their metastatic potentials. It was of interest to test whether inhibition of metastatic properties of BL6 melanoma cells is specifically associated with the appearance of the terminal alpha-Gal or whether capping N-acetyllactosamine with another oligosaccharide would also affect the metastatic properties of BL6 melanoma cells. For this purpose, BL6-2 clone isolated from B16BL6 melanoma was transfected with the alpha1,2-fucosyltransferase (alpha1,2FT) cDNA. The alpha1,2FT catalyzes a transglycosylation reaction, resulting in syntheses of the Fuc(alpha)1-2Gal(beta)1-4GlcNAc-R structure, which is known as the H antigen of O blood group in humans and is also synthesized in some cells of mice. Transfection of BL6 melanoma cells with the alpha1,2FT cDNA resulted in the appearance of the terminal Fuc(alpha)1-2Gal(beta)1-4GlcNAc-R epitopes reacting with the Ulex europaeus agglutinin lectin. In parallel, the transfected cells showed a decrease in N-acetyllactosamine sialylation. Decline in sialylation of the transfected cells is likely to be the result of competition between alphal,2FT and alpha2,3- or alpha2,6-sialyltransferases for the common substrate N-acetyllactosamine (Gal(beta)1-4GlcNAc-R) on N-linked carbohydrate chains of glycoproteins and glycolipids. The alpha1,2FT-transfected BL6-2 cells showed an increase in homotypic aggregation. In parallel, metastatic ability of the alpha1,2FT-transfected BL6-2 cells was reduced significantly in the immunocompetent as well as immunosuppressed (X-irradiated) mice. Thus, these data imply that capping N-acetyllactosamine with alphaGal or alphaFuc and the corresponding reduction in sialylation of BL6-2 melanoma cells were associated with reduction of their metastatic potential.     

Fabrication of PLA/PEG/MWCNT electrospun nanofibrous scaffolds for anticancer drug delivery

In the present study, polylactic acid (PLA)/polyethylene glycol (PEG)/multiwalled carbon nanotube (MWCNT) electrospun nanofibrous scaffolds were prepared via electrospinning process and their applications for the anticancer drug delivery system were investigated. A response surface methodology based on Box–Behnken design (BBD) was used to evaluate the effect of key parameters of electrospinning process including solution concentration, feeding rate, tip–collector distance (TCD) and applied voltage on the morphology of PLA/PEG/MWCNT nanofibrous scaffolds. In optimum conditions (concentration of 8.15%, feeding rate of 0.2 mL/h, voltage of 18.50 kV and TCD of 13.0 cm), the minimum experimental fiber diameter was found to be 225 nm which was in good agreement with the predicted value by the BBD analysis (228 nm). In vitro drug release study of doxorubicin (DOX)‐loaded nanofibrous scaffolds, higher drug content induced an extended release of drug. Also, drug release rate was not dependent on drug/polymer ratio in different electrospun nanofibrous formulations. The equation of M_t = c₀ + kt^0.5was used to describe the kinetic data of DOX release from electrospun nanofibers. The cell viability of DOX‐loaded nanofibrous scaffolds was evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide, a tetrazole assay on lung cancer A549 cell lines. We propose that DOX‐incorporated PLA/PEG/MWCNT nanofibrous scaffold could be used as a superior candidate for antitumor drug delivery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41286.     

New approach for time-resolved and dynamic investigations on nanoparticles agglomeration

Nanoparticle (NP) colloidal stability plays a crucial role in biomedical application not only for human and environmental safety but also for NP efficiency and functionality. NP agglomeration is considered as a possible process in monodispersed NP colloidal solutions, which drastically affects colloidal stability. This process is triggered by changes in the physicochemical properties of the surrounding media, such as ionic strength (IS), pH value, or presence of biomolecules. Despite different available characterization methods for nanoparticles (NPs), there is a lack of information about the underlying mechanisms at the early stage of dynamic behaviors, namely changing in NP size distribution and structure while placing them from a stable colloidal solution to a new media like biological fluids. In this study, an advanced in situ approach is presented that combines small angle X-ray scattering (SAXS) and microfluidics, allowing label-free, direct, time-resolved, and dynamic observations of the early stage of NP interaction/agglomeration initiated by environmental changes. It is shown for silica NPs that the presence of protein in the media enormously accelerates the NP agglomeration process compared to respective changes in IS and pH. High IS results in a staring agglomeration process after 40 min, though, in case of protein presence in media, this time decreased enormously to 48 s. These time scales show that this method is sensitive and precise in depicting the dynamics of fast and slow NP interactions in colloidal conditions and therefore supports understanding the colloidal stability of NPs in various media concluding in safe and efficient NP designing for various applications.