Characterization of Vortex Development and Thermo-Solutal Transfers on Confined Wall Jets Submitted to Suction or Blowing: Part 2

A computational study is conducted to explore the effect of vertical wall suction or blowing on two-dimensional confined wall jet hydrodynamic characteristics. Using an implicit finite volume technique in Cartesian coordinate system, several parameters have been investigated for a wide range of Lewis numbers by fixing the Prandtl number at 7 that corresponds to water. The main purpose is to analyze the control size and location effectiveness on the flow pattern as well as heat and mass transfer rates. Detailed numerical simulations demonstrated that as the local blowing is moved downstream, discrete vortex formation begins at a critical location then shedding phenomenon occurs behind the slot at advanced positions. Since the flow dynamic structure is mainly altered, averages skin friction and thermo-solutal coefficients distributions are largely influenced. Approximately for x_s≤4 (upstream of the natural vortex emission position), Nusselt and Sherwood numbers slightly increase with the control location x_s. However, they gradually decrease as the blowing slot approaches the domain exit. Optimum values were obtained when locating the slot just downstream of the uncontrolled Kelvin-Helmholtz instability onset. Furthermore, computations illustrated that an appropriate suction slot length selection could be a simple and efficient tool to delay or even suppress natural structure emission and development. This choice is essentially related to the recirculation cell size

Identification of peptides with antioxidant and antihypertensive capacities by RP-HPLC-Q-TOF-MS in dry fermented camel sausages inoculated with different starter cultures and ripening times

Low molecular weight peptides are produced during meat fermentation. They contribute to generate flavor compounds but they can also exert certain bioactivities. The aim of this work was to evaluate, for the first time, the generation of bioactive peptides during the preparation of dry fermented camel sausages and to study the influence of the ripening time and the starter culture on bacteria growing, peptide concentration and size, and antioxidant and antihypertensive capacities of peptides. Camel meat sausages inoculated with different starter bacteria and non-inoculated were ripened up to 28 days. Results demonstrated that bacteria population, peptide concentration, and peptide size were affected by the ripening time and the inoculated bacteria. Moreover, the ripening process resulted in an increasing antioxidant and antihypertensive capacity showing the highest bioactivities in fractions with peptides below 3 kDa. Peptides in these fractions were identified by RP-HPLC-Q-TOF-MS analysis. Identified peptides showed common features with peptides with antioxidant or anti hypertensive activity

Commercial window glass tested as possible high dose dosimeter. Electron and gamma irradiation

The use of commercial window glass as possible high dose routine dosimeter has been investigated. Glass samples have been irradiated with doses in the range of 1-50 kGy using 60Co γ source, 4 MeV and 12 MeV electron accelerators. The samples were given a post irradiation thermal treatment (150 oC for 20 min) in order to improve the post irradiation stability of the measured specific optical absorbance, since a rapid fading of the optical absorbance has been observed at room temperature immediately after irradiation. The optical absorbance measurements of the irradiated samples, kept in the dark and at room temperature, were carried on for several weeks. The samples submitted to heat treatment showed a decrease of about 10-15% of the specific optical absorbance that became much less pronounced after 10 days from the irradiation. The response of the window glass plates is energy and dose rate dependent. This study shows the feasibility of using commercial window glass as a routine dosimeter in a certain dose range after proper calibration in the irradiation plant where they are going to be used

Biochemical status, oxidative and antioxidant responses after 3-month specific training in elite karate athletes

Aim To investigate the effects of 3-month-long specific training program on biochemical status, oxidative and antioxidant responses in elite karatekas. Methods Twenty male karatekas [BMI: 21.9 ± 2.4 (kg/m2)] participated in this study. They performed a 3-month specific training to prepare for an international competition. We measured selected biochemical parameters, the oxidative and antioxidant responses before (T0) and after 3 months of intense karate training (T1). Results We found significant increases in catalase activity (26.3% ± 21.3%, p  Conclusions The specific training program improves the prooxidant–antioxidant balance of elite karate athletes. It could be recommended for athletes having similar physical fitness level

Imidazolium-based ionic liquid type dependence of the bending response of polymer actuators

Actuators based on polymer blends of poly(vinylidene fluoride) (PVDF) with 40 % of different ionic liquids (IL) are prepared by solvent casting. [C2mim][Cl], [C6mim][Cl], [C10mim][Cl], [C2mim][NTf2], [C6mim][NTf2] and [C10mim][NTf2] were selected in order to evaluate the effect of anion and cation sizes in the bending properties. The microstructure, mechanical and electrical properties of the blend depend on the IL type, which in turn leads to a different bending response. In particular, the mechanical properties are independent on the IL type but the AC conductivity of the composites depend more on the anion type than on the size of the alkyl chain connected to the imidazolium based cation. Thus, the bending response of the IL/PVDF composites is correlated with the anion and cation sizes and a maximum bending response of 0.3 % is achieved for a 10 volts square signal in the IL/PVDF composite with 40 wt% content of [C2mim][NTf2].The authors thank FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under Strategic Funding UID/FIS/04650/2013, UID/Multi/04551/2013, UID/QUI/50006/2013, project PTDC/EEI-SII/5582/2014, a contract under Investigador FCT 2012 program (J.M.S.S.E.), and grants SFRH/BD/90215/2012 (JCD) and SFRH/BPD/112547/2015 (CMC). Financial support from the Basque Government Industry Department under the ELKARTEK Program is also acknowledged. The authors (R. M. and S. B. H.) would like to thank the Tunisian Ministry of Higher Education and Research for its financial support. The authors thank the support of M. S. Martins (U. Minho) for supporting the electromechanical measurements

Polarization-Sensitive Photodetectors Based on Directionally Oriented Organic Bulk-Heterojunctions

Polarized spectroscopic photodetection enables numerous applications in diverse areas such as sensing, industrial quality control, and visible light communications. Although organic photodetectors (OPDs) can offer a cost-effective alternative to silicon-based technology—particularly when flexibility and large-area arrays are desired—polarized OPDs are only beginning to receive due research interest. Instead of resorting to external polarization optics, this report presents polarized OPDs based on directionally oriented blends of poly(3-hexylthiophene) (P3HT) and benchmark polymer or nonfullerene acceptors fabricated using a versatile solution-based method. Furthermore, a novel postprocessing scheme based on backfilling and plasma etching is advanced to ameliorate high dark-currents that are otherwise inherent to fibrillar active layers. The resulting polarized P3HT:N2200 OPDs exhibit a broad enhancement across all principal figures of merit compared to reference isotropic devices, including peak responsivities of 70 mA W$^{-1}$ and up to a threefold increase in 3 dB bandwidth to 0.75 MHz under parallel-polarized illumination. Polarization ratios of up to 3.5 are obtained across a spectral range that is determined by the specific donor–acceptor combinations. Finally, as a proof-of-concept demonstration, polarized OPDs are used for photoelasticity analysis of rubber films under tensile deformation, highlighting their potential for existing and emerging applications in advanced optical sensing

Hygrothermal aging effects on mechanical and fatigue behaviors of a short-natural-fiber-reinforced composite

A new natural fiber composite made of high density polyethylene (HDPE) and 40% wt of short birch fibers (SBF) was developed to replace polyamide (better known under its industrial name “Nylon”) in spur gear manufacturing. The effect of hygrothermal aging on quasi-static and fatigue bending behaviors of this new composite has been studied in this work. Once hygrothermal aging is completed, flexural quasi-static tests have been performed on aged specimens and results compared with those obtained from unaged specimens. It has been observed that hygrothermal aging has no significant effect on flexural mechanical properties of this composite. After characterization, bending fatigue tests have been conducted on aged specimens and results have been compared with those of unaged specimens. These fatigue tests show that hygrothermal aging decreases the high cycles fatigue strength (HCFS) of this composite. The cause of this fatigue durability decrease has been investigated using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and a scanning electron microscope (SEM). These tests show that the chemical composition and thermal behavior of this composite are not affected by hygrothermal aging. On the contrary, these tests show that damage mechanisms of this composite (HDPE/40% wt of SBF) are directly affected by this type of aging

Fatigue life and residual strength of a short-natural-fiber-reinforced plastic vs Nylon

A new natural fiber composite made of high density polyethylene (HDPE) and short birch fibers (SBF) was developed to replace high-performance thermoplastics (Polyamide) commonly used in gears manufacturing. 3-point flexural quasi-static tests were achieved on bending specimens to assess mechanical properties. Comparison between these results and those of polyamide (PA) and neat polyethylene has showed that the polyethylene reinforced with 40%wt of SBF presents tensile and flexural mechanical properties that are higher than those of the PA11 or the neat polyethylene. After static characterisation, fatigue tests were performed to determine ε-N curves and the evolution of residual strength. Then, the fatigue behavior of the studied composite has been compared with that of PA66 and of ultra-high molecular weight polyethylene (UHMWPE). It has been noticed that polyethylene reinforced with 40%wt of SBF presents a high cycle fatigue strength (HCFS) that is more important than that of PA66 and UHMWPE. Consequently, the studied composite represents a good alternative to replace Nylon in spur gears manufacturing