Influence of TiO2 nanoparticles on nonisothermal crystallization of PP in a wide range of cooling rates analyzed by fast scanning DSC

The influence of titanium dioxide (TiO₂) nanoparticles on the crystallization behavior of polypropylene was investigated by conventional differential scanning calorimetry (DSC) and fast scanning DSC measurements. The data obtained from both methods were estimated for the first time using the Lauritzen‐Hoffmann equation to analyze the behavior over a wide cooling range under nonisothermal conditions. This provides more reliable values of nucleation parameters (K_g) and surface free energy (σ_e). The variation of the effective energy (ΔE) was determined with the Kissinger method. Regardless of the cooling rate, both K_g and σ_e indicate the role of titania as a nucleating agent enhances the crystallization rate. However, the ΔE denotes that TiO₂ acts as an obstacle to the mobility of chain segments at cooling rates below 150 °C/s, while, in contrast, the presence of titania enhances the chain mobility at cooling rates above 150 °C/s. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43944.     

Pectin changes in the pre-cooking step of dehydrated mashed potato production

Some in-vivo and in-vitro characteristics of pectin methylesterase (PME) from cell wall and whole potato tuber were determined and its role was elucidated in the pre-cooking and cooling steps of commercial dehydrated mashed potato production. The isolated cell walls contained 16.3% anhydrogalacturonic acid with a degree of esterification (DE) of 56, and 25% of tuber total PME. Cell wall pre-cooking in model systems resulted in a DE of 53.2. Native cell wall pectin solubilisation was much less than that of H-cell walls devoid of metal cations. Calcium but not Mg, supplied as Ca(Mg)-starches, retarded pectin solubilisation, while Ca-uptake by retained pectin was high when cooling followed pre-cooking. Texture measurements of potato slices pre-cooked, cooled and cooked suggested a firming effect which could be attributed to Ca-release from gelatinised starch during pre-cooking, and stabilisation of Cabridges with free COO^? groups of cell wall pectin duringcooling. The role ascribed to PME in causing firming is de-emphasised.     

The effect of iron and manganese on the recrystallization behavior of hotrolled and solution-heat-treated aluminum alloy 6013

The influence of manganese and iron additions on the recrystallization behavior of a hot-rolled Al-Mg-Si-Cu alloy has been investigated. In the as-cast ingot, some manganese remains in supersaturated solid solution and, during the preheating step, precipitates as fine (0.1 to 0.3 μm) dispersoidsα- Al₁₂Mn₃Si and α(AlFeMnSi), depending on the local iron content. The presence of the dispersoids increases the alloy’s resistance to recrystallization. The remaining manganese along with iron forms coarse (30 to 100 μm) α(AlFeMnSi) phases in the interdendritic channels upon solidification. During rolling, these coarse phases are broken up and the matrix surrounding the phases is highly strained. The highly strained regions around the precipitates are preferential sites for the nucleation and growth of new, strain-free, recrystallized grains. Decreasing the iron content decreases the amount of coarse α(AlFeMnSi) constituent phase and increases the recrystallization resistance of the alloy for a given concentration of manganese. For iron-free alloys, coarse α-Al₁₂Mn₃Si phase forms during solidification. The increased recrystallization resistance is attributed to the lower probability for particle-stimulated recrystallization. Increasing the manganese content beyond what is normally found in 6013 increases the volume fraction of both the dispersoids and the coarse constituent phases. However, the increased volume fraction of the dispersoids in the iron-containing alloys more than compensates for the increase in volume fraction of coarse constituent particles, resulting in an increase in the recrystallization resistance with increased manganese content. In this research, alloys containing varying amounts of manganese and iron with levels of magnesium, silicon, and copper consistent with the nominal composition of 6013 were hot deformed and solution heat treated to produce microstructures ranging from fully recrystallized to unrecrystallized.     

Antimicrobial activity of vanillin against spoilage microorganisms in stored fresh-cut mangoes

The antimicrobial activity of vanillin against four bacteria (Pantoea agglomerans, Aeromonas enteropelogenes, Micrococcus lylae, and Sphingobacterium spiritovorun), four fungi (Alternaria sp., Aspergillus sp., Penicillium sp., and Fusarium sp.), and three unidentified yeasts isolated from spoiling fresh-cut mango slices was verified in laboratory media adjusted to pH 5.0. MICs of vanillin against the fungi (12.5 to 13.3 mM), bacteria (10 to 13.3 mM), and yeasts (5.0 to 6.7 mM) indicated that all the test species were sensitive to the antimicrobial effects of vanillin. Fresh-cut mango slices were dipped for 1 min in solutions containing 40 and 80 mM vanillin before being packaged in rigid trays and stored at 5 and 10 degrees C to verify the effects of vanillin on the development of the spoilage microflora. Microbiological analysis for up to 14 days of storage revealed that treatment with 80 mM vanillin significantly delayed (P < 0.05) the development of total aerobic bacteria and yeast and mold populations. Vanillin may be a practical preservative for processing fresh-cut mango.     

Spray coating thin polymeric sensor films for Au3+

A novel polymeric sensor of the poly(sodium-4-styrenesulfonate) (PSS)-modified rhodamine B derivative (Rho) was synthesized using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N,N′-dimethylpyridin-4-amine (DMAP) as coupling reagents to obtain PSS-Rho4 in 21% yield. The characterization and “Off–On” sensing phenomena were established through UV–Vis, fluorescence, NMR, and FTIR techniques. The PSS-Rho4 showed high selectivity and sensitivity for Au³⁺ over other metal ions. Upon the addition of Au³⁺, significant color change and “Off–On” fluorescence were observed due to a cation Au³⁺ induced spirolactam ring-opening process with detection limit down to micromolar values (1.2 μM). In addition, spray coating thin polymeric sensor films were produced onto the surface of material (PSS-Rho4-ITO and PSS-Rho4-filtered paper) providing a fast, portable, and easy-to-use molecular device for the detection of Au³⁺ in the real system. Reversibility was evaluated by rinsing with EDTA solution under basic condition. We believe that, this approach provides a sensitive and accurate method for the detection of Au³⁺ in environmental and biological applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48273.     

Fishing Vessels Behavior Identification for Combating IUU Fishing: Enable Traceability at Sea

Wireless Personal Communications - Overfishing is a critical catastrophe to the ecosystem and the global food chain. The leading causes are Illegal Unreported and Unregulated Fishing (IUU Fishing)...     

The effect of cooling rate from the melt on the recrystallization behavior of aluminum alloy 6013

In most commercial operations, the plant metallurgist likely has little control over the solidification rate of the process. However, solidification rate is affected by the dimensions of the ingot, and product form (plate ingot vs extrusion billet, for example) determines the dimensions of the ingot to be cast. Consequently, understanding the effects of solidification rate might be useful in explaining differences in microstructure that are often observed in various product forms cast from equivalent compositions. To provide this microstructural information, the effect of cooling rate from the melt on the microstructural changes in hot-rolled and solution heat treated (SHT) aluminum alloy 6013 was investigated. The range of cooling rates in this investigation is comparable to what might be observed through the thickness of a plate ingot. Over the cooling rate range investigated (0.5 to 5 K/s), recrystallization behavior of the alloy appears to be primarily affected by the size and number density of the coarse α(AlFeMnSi) constituent particles, which act as sites for particle stimulated nucleation (PSN) of recrystallized grains. At intermediate cooling rates (1.5 K/s), the resistance to recrystallization is at a minimum. As the cooling rate increases beyond 1.5 K/s, the number of particles available for PSN decreases; thus, there is a decrease in the fraction of recrystallized grains after heat treating. On the other hand, as the cooling rate is decreased from 1.5 K/s, the size of the constituents increases; however, their number decreases, once again leading to a decrease in the fraction of recrystallized grains observed after heat treatment.     

A minimum five‐component five‐term single‐nonlinearity chaotic jerk circuit based on a twin‐jerk single‐op‐amp technique

A minimum 5‐component 5‐term single‐nonlinearity chaotic jerk circuit is presented as the first simplest chaotic jerk circuit in a category that a single op‐amp is employed. Such a simplest circuit displays 5 simultaneous advantages of (1) 5 minimum basic electronic components, (2) 5 minimum algebraic terms in a set of 3 coupled first‐order ordinary differential equations (ODEs), (3) a single minimum term of nonlinearity in the ODEs, (4) a simple passive component for nonlinearity, and (5) a single op‐amp. The proposed 5‐term single‐nonlinearity chaotic jerk circuit and a slightly modified version of an existing 6‐term 2‐nonlinearity chaotic jerk circuit form mirrored images of each other. Although both mirrored circuits yield 2 different sets of the ODEs, both sets however can be recast into a pair of twin jerk equations. Both mirrored circuits are therefore algebraically twin 5‐component chaotic jerk circuits, leading to a twin‐jerk single‐op‐amp approach to the proposed minimum chaotic jerk circuit. Two cross verifications of trajectories of both circuits are illustrated through numerical and experimental results. Dynamical properties are also presented.