•Atmospheric argon plasma treatment induced non-chemical modification of starch.•Cross-linking and depolymerization are competitive reactions induced by argon plasma.•Sample preparation and power ...supply determined predominant effect of these reactions.•Cross-linking predominated for granular starch at 50W and cooked starch at 100W.•Depolymerization predominated for granular starch at 100W and cooked starch at 50W.
Non-chemical modification of tapioca starch was investigated using jet atmospheric argon plasma treatment. Two forms of starch slurry, i.e. granular starch (G) and cooked starch (C), were jet-treated by argon plasma generated by supplying input power of 50W (denoted as G50 and C50 samples) and 100W (denoted as G100 and C100 samples) for 5min. Physical, rheological, and structural characteristics of the modified starch were investigated. The G50 and C100 samples had lower paste clarity but higher thermal stability and performed stronger gels (G50 only) compared to their control counterparts. On the other hand, the analyzed properties of the G100 and C50 samples showed the opposite trend. FTIR and 1H NMR results revealed that the relative areas of COC and OH peaks were changed after the treatment. Cross-linking reaction seemed to predominantly take place for the G50 and C100 samples, whereas depolymerization predominated for the G100 and C50 samples.
•Tapioca starch was cross-linked using different concentrations of STMP/STPP mixture.•Effect of cross-linking levels on physicochemical properties of starch was studied.•Starch cross-linked with 1% ...STMP/STPP mixture gave gel with the highest consistency.•Soup containing 1% STMP/STPP cross-linked starch had the best sensory quality.
Physicochemical properties of cross-linked tapioca starch (CLTS) with different cross-linking levels and their application as a thickening agent in soups were studied. The CLTS was prepared by cross-linking native tapioca starch suspended in alkaline solution (41.67% (w/w), pH 11) using a mixture (99:1 (w/w) ratio) of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) at different concentrations ranged from 0.25% to 6.0% (w/w of starch) at 45°C for 3h. Starch paste clarity decreased with increasing concentration of STMP/STPP mixture. Variations of swelling power, solubility, pasting, gelatinization, and rheological properties of the CLTS were found. Thermogravimetric analysis exhibited higher thermal stability for the CLTS granules compared to the native one. Among the samples, the CLTS prepared using 1.0% STMP/STPP (1.0%-CLTS) and soup containing the 1.0%-CLTS exhibited the strongest gel characteristic and the greatest shear resistant properties. The 1.0%-CLTS improved the textural properties and sensory quality of soups.
To develop a novel modification process of tapioca starch using low-pressure argon plasma treatment in a large-scale production, a semi-continuous downer reactor was designed to provide a production ...rate of 0.1–0.5 kg per cycle. Physicochemical and rheological properties of plasma-treated starch were investigated in order to predict the phenomena occurred during the plasma treatment. Native tapioca starch (NTS) was plasma-treated for 1, 3, or 6 cycles, which were referred to as PTS-1, PTS-3, or PTS-6 samples, respectively. Plasma treatment of the NTS resulted in a significant decrease (
P
< 0.05) in paste clarity and Rapid Visco Analyzer (RVA) breakdown viscosity, and an increase in gel strength of starch. The PTS-1 had the lowest paste clarity of 39.85 %
T
at 650 nm and breakdown viscosity of 29.71 Rapid Visco Unit (RVU), and the highest gel strength, e.g.,
G′
= 5.47
ω
0.32
. With increasing the number of treatment cycles, i.e., the PTS-3 and PTS-6, the paste clarity and breakdown viscosity significantly increased (
P
< 0.05), while the gel strength decreased. The Fourier transform infrared (FTIR) spectroscopy via relative areas of C–O–C peaks indicated that the PTS-1 had a significant increase (
P
< 0.05) in the C–O–C cross-linked bonds compared to the NTS, but the effect of depolymerization could further suppress the cross-linking reaction when the number of treatment cycle was increased. Taking an advantage of a very short residence time (less than 0.3 s) in the plasma downer reactor, the semi-continuous process of starch modification could be developed for a commercial production of non-chemically modified starch with a relatively low degree of cross-linking.
The wound-healing process can be disrupted at any stage due to various internal and external factors. The inflammatory stage of the process plays a vital role in determining the outcome of the wound. ...Prolonged inflammation due to bacterial infection can lead to tissue damage, slow healing, and complications. Wound dressings made using materials such as poly (vinyl alcohol) (PVA), chitosan (CS), and poly (ethylene glycol) (PEG) with Mangifera extract (ME) added can help reduce infection and inflammation, creating a conducive environment for faster healing. However, creating the electrospun membrane is challenging due to balancing various forces such as rheological behavior, conductivity, and surface tension. To improve the electrospinnability of the polymer solution, an atmospheric pressure plasma jet can induce chemistry in the solution and increase the polarity of the solvent. Thus, this research aims to investigate the effect of plasma treatment on PVA, CS, and PEG polymer solutions and fabricate ME wound dressing via electrospinning. The results indicated that increasing plasma treatment time increased the viscosity of the polymer solution, from 269 mPa∙to 331 mPa∙s after 60 min, and led to an increase in conductivity from 298 mS/cm to 330 mS/cm and an increase in nanofiber diameter from 90 ± 40 nm to 109 ± 49 nm. Incorporating 1% mangiferin extract into an electrospun nanofiber membrane has been found to increase the inhibition rates of
and
by 29.2% and 61.2%, respectively. Additionally, the fiber diameter decreases when compared with the electrospun nanofiber membrane without ME. Our findings demonstrate that electrospun nanofiber membrane with ME has anti-infective properties and can promote faster wound healing.
Constructing microstructure-property-processing relationships in polycrystalline metals remains a challenge mainly due to the lack of quantitative relations between grain boundary (GB) energies and ...populations as well as the macroscopic properties associated with the processing dependent microstructure. Here, we present a universal function for computing the energies of arbitrary GBs in body-centered cubic (bcc) metals. The effectiveness of the universal function in describing the variations of the GB energies is demonstrated by consistency between the output of the function and the energies of ∼ 2,500 GBs simulated by the embedded atom method. Large-scale comparisons between the interpolated energies and measured GB populations in W, Fe and ferritic steel reveal that the population distributions are governed by local energy minima located at the Σ1, Σ3, Σ9, Σ11, and Σ33a misorientations, representing a major step forward for the grain boundary engineering (GBE) of bcc metals.
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Describing microstructure evolution in tungsten requires a quantitative description of the anisotropic grain boundary energy. We present a grain boundary energy function for tungsten that specifies ...the energy of an arbitrary boundary given its five macroscopic crystallographic parameters. A comparison of measured grain boundary areas and the grain boundary energies given by the function at the Σ11, Σ17b, and Σ33a misorientations, which are problematic to determine by measurement or atomistic calculations, reveals inverse correlations that are similar to what have been observed in other metals.
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•Successful preparation of dealloyed ternary Cu@Pt-Ru core-shell electrocatalyst.•Preparation of Cu@Pt-Ru core-shell electrocatalyst by cyclic co-electrodeposition and selective ...copper dealloying (CCED-SCuD).•Excellent catalytic activity of Cu@Pt-Ru core-shell electrocatalyst for methanol electrooxidation.
Dealloyed ternary Cu@Pt-Ru core-shell electrocatalysts supported on carbon paper (CP) are fabricated by cyclic-co-electrodeposition and selective copper dealloying (CCED-SCuD). The physical properties of this catalyst such as surface and bulk compositions, electronic structure modification, phase structure, crystallite size, compressive lattice strain, and morphology were characterized by X-ray photoemission (XPS), inductive-coupling plasma atomic spectroscopy (ICP-AES), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscope, and transmission electron microscope (TEM). The best catalyst is Cu@Pt-Ru/CP, having core-shell structure with a Cu rich core and a Pt-Ru rich shell with grain size around 100nm. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) reveal that ternary Cu@Pt-Ru/CP gives significantly low onset potential and high activity towards methanol electrooxidation reaction (MOR), achieving specific peak current at 265mA.mgPt−1, which is significantly higher than that of dealloyed binary Cu@Pt/CP (211mA.mgPt−1) and pure Pt/CP (170mA.mgPt−1). The highest current stability is found for the ternary Cu@Pt-Ru/CP with decay rate at 2.3×10−3mA.mgPt−1.s−1. The enhancements of both activity and stability of the Cu@Pt-Ru/CP from the higher electrochemical surface area (ECSA) are major reason, which originates from the higher exposed surface of Pt, while the higher compressive lattice strain, electronic structure modification, and bi-functional mechanism are minor reason. However, the lower current density (JP) of the ternary Cu@Pt-Ru/CP suggests lower intrinsic reactivity.
Describing microstructure evolution in tungsten requires a quantitative description of the anisotropic grain boundary energy. Here we present a grain boundary energy function for tungsten that ...specifies the energy of an arbitrary boundary given its five macroscopic crystallographic parameters. A comparison of measured grain boundary areas and the grain boundary energies given by the function at the Σ11, Σ17b, and Σ33a misorientations, which are problematic to determine by measurement or atomistic calculations, reveals inverse correlations that are similar to what have been observed in other metals.
In this study, we prepared and characterized carbon paper-supported dealloyed binary Pt–Cu core–shell electrocatalysts (denoted as PtxCu(100−x)/CP) by cyclic co-electrodeposition and selective copper ...dealloying in an acidic medium, and we investigated the effect of the copper content in the samples on the catalytic activities toward methanol electroxidation reaction (MOR). X-ray photo-emission spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) indicated that the structure of dealloyed binary Pt–Cu catalysts possessed a Pt-rich shell and a Cu rich core. X-ray absorption near edge spectroscopy (XANES) displayed that the oxidation states of Pt and Cu were zero and one, respectively, implying the formation of metallic Pt and Cu2O, respectively. X-ray diffraction spectroscopy (XRD) confirmed that Cu was inserted into a face-centered cubic Pt structure forming Pt–Cu alloys. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) displayed a cubic shape of Pt/CP and a spherical shape of PtxCu(100−x)/CP with several hundred nanometer sizes of agglomeration that depended on the Cu content. Cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were performed to confirm that the sample of Pt70Cu30/CP exhibited the best catalytic activities in terms of the specific current, current density, catalytic poisoning tolerance, and stability.
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•Binary electrocatalysts of PtxCu(100−x)/CP were prepared by cyclic co-electrodeposition and selective copper dealloying.•The structures of PtxCu(100−x)/CP were a Pt rich shell and a Cu rich core.•The Pt70Cu30/CP was the excellent catalytic activity towards methanol electrooxidation and COads tolerance.
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