This paper presents a review on the resistance spot welding (RSW) of Al/Al alloys, Al alloys/steel, Al/Mg alloys, and Al/Ti alloys, with focus on structure, properties, and performance relationships. ...It also includes weld bonding, effect of welding parameters on joint quality, main metallurgical defects in Al spot welds, and electrode degradation. The high contact resistance, induced by the presence of oxide layer on the surface of Al alloys, and the need for application of high welding current during RSW of Al alloys result in rapid electrode tip wear and inconsistency in weld quality. Studies have shown that cleaning the oxide layer, sliding of a few microns between sheets, enhancing the electrode force, and the application of a low-current pre-heating can significantly reduce the contact resistance and improve joint quality. For Al/steel dissimilar RSW, the technique of resistance element welding, the use of optimized electrode morphology, the technique of RSW with cover plates, and the use of interlayers such as Al-Mg, AlSi12, and AlCu28 alloys were found to suppress the formation of brittle intermetallic compounds (IMC) and improve the joint quality. The employment of pure Ni foil, Au-coated Ni foil, Sn-coated steel, and Zn-coated steel interlayers was also found to restrict the formation of brittle IMCs during RSW of Al/Mg alloys. Furthermore, the techniques of RSW with cover plates and RSW under the influence of electromagnetic stirring effect were found to improve the weldability of Al/Ti dissimilar alloys.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide), BmImTFSI based poly(methyl methacrylate)-poly (vinyl chloride), PMMA-PVC gel polymer electrolytes were prepared by solution casting ...technique. These ionic liquid-based gel polymer electrolytes exhibit Arrhenius type temperature dependence of ionic conductivity. The highest ionic conductivity of (8.08
±
0.01)
×
10
−
4
Scm
−1 was achieved at 80
°C upon addition of 60
wt.% of BmImTFSI. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies revealed the amorphous nature and morphology of these polymer electrolytes, respectively. The lower coherence length of the peak inferred the higher amorphous degree in these polymer matrices. Decreases in
T
g
and
T
m
indicate the flexibility of polymer backbone. The amorphous behavior of these ionic liquid-based gel polymer electrolytes are also enhanced as shown in differential scanning calorimetry (DSC) analysis. On the contrary, thermogravimetric analysis (TGA) divulges that the thermal stability of polymer electrolytes has been improved upon impregnation of BmImTFSI.
► BmImTFSI is the ionic liquid used in PMMA-PVC based polymer electrolytes. ► The presence of ionic liquid increases the ionic conductivity. ► XRD and SEM reveal the amorphous nature of the ionic liquid polymer electrolytes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Salmonella infection has become a foremost health issue as it is the causative agent of several foodborne outbreaks. Currently, there is a huge demand for safe, healthy, and nutritious, fresh-like ...food products. It strongly suggests the food manufacturers to develop appropriate practices like expeditious testing, detection, and inactivation of foodborne pathogens as well as to prevent the pathogen entry into the supply chain.
In this decade, a lot of innovative ideas and technologies have been investigated as a substitute for conventional thermal technologies employed to inactivate foodborne pathogens. This review presents the potential of such technologies for instance, cold plasma, light-emitting diode, ozone, ultrasound, and pulsed electric field in decontaminating the Salmonella in food production and supply chain. These emerging innovative decontamination practices not only ensure the freshness of food but also enhance the microbial safety and quality of a food product. The synergistic effect of the cold plasma technique arrests the pathogenic cells’ viability and multiplication. Oxidative response and the free radical generation capability of ozone treatment destroy the bacterial cells and accord antimicrobial activity. Applications of acoustic cavitation mechanism of ultrasound and non-ionizing electromagnetic radiations of UV light progressively inactivate the pathogenic microorganisms. The high-intensity usage of electric field strength by utilizing the electroporation method resulting in microbial cell death.
The effect of emerging non-thermal technologies and the processing parameters involved in the decontamination have been reviewed comprehensively along with the summary of different food products. A thorough understanding and deep insights into the mechanisms underlying the optimization of the process conditions will pave the way for upscaling these technologies for improved quality and sustaining the nutritional components of the food product.
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•Salmonella induced illness continues to be a major health concern worldwide.•Non-thermal technologies exhibit efficient decontamination with less impact on food quality.•Oxidative properties of cold plasma and ozone impose detrimental effects on bacterial cell.•LED/UV illumination of microbial photosensitizers releases reactive species with cytotoxic effect.•Hurdle approach showed enhanced antimicrobial effect on Salmonella.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The simplest method of synthesizing metallic Cu (111) nanoparticles on the zinc–aluminum mixed oxides was found to be easily obtained by solid state grinding of all the three metal nitrates and ...organic compounds in suitable proportions. Organic compounds such as citric acid, formic acid, and hydrazine were used, which act as reducing agents for Cu. The catalysts were characterized by various physicochemical methods such as X-ray diffraction, X-ray fluorescence, temperature programmed reduction, high-resolution transmission electron spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and N2-physisorption. The use of citric acid resulted in Cu(111) nanoparticles with higher surface area and better dispersion on the surface of mixed oxides. The catalysts were used for the selective hydrogenation of furfural to furfuryl alcohol under vapor phase conditions. Among the various catalysts studied, citric acid-assisted catalysis showed better conversion with higher selectivity of desired product and deactivation free catalytic activity on stream more than 30 h.
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IJS, KILJ, NUK, PNG, UL, UM
Novel pH sensitive N-succinyl chitosan-g-poly (acrylic acid) hydrogels were synthesized through free radical mechanism. Rheometer was used to observe the mechanical strength of the hydrogels. In ...vitro degradation was conducted in SIF (pH 7.4). The effect of concentration of monomers, initiator, and crosslinking agent and pH and ionic strength of NaCl, CaCl2, and AlCl3 on swelling of the hydrogels was observed. The results showed that equilibrium swelling ratio was highly influenced by concentration of monomers, initiator, and crosslinking agent concentration, and pH and salt solutions of NaCl, CaCl2, and AlCl3. The swelling kinetics revealed that swelling followed non-Fickian anomalous transport. Furthermore, theophylline loading (DL %) and encapsulation efficiency (EE %) of the hydrogels was in the range of 15.5 ± 0.15–22.8 ± 0.06% and 62 ± 0.15–91 ± 0.26%, respectively. The release of theophylline in physiological mediums was strongly influenced by the pH. The theophylline release was in the range of 51 ± 0.20–92 ± 0.12% in SIF and 7.4 ± 0.02–14.9 ± 0.03% in SGF (pH 1.2), respectively. The release data fitted well to Korsmeyer-Peppas model. The chemical activity of the theophylline suggested that drug maintained its chemical activity after release in vitro. The results suggest that synthesized hydrogels are excellent drug carriers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Immunoglobulin G4 antibodies exhibit unusual properties with important biological consequences. We report the structure of the human full-length IgG4 S228P anti-PD1 antibody pembrolizumab, solved to ...2.3-Å resolution. Pembrolizumab is a compact molecule, consistent with the presence of a short hinge region. The Fc domain is glycosylated at the CH2 domain on both chains, but one CH2 domain is rotated 120° with respect to the conformation observed in all reported structures to date, and its glycan chain faces the solvent. We speculate that this new conformation is driven by the shorter hinge. The structure suggests a role for the S228P mutation in preventing the IgG4 arm exchange. In addition, this unusual Fc conformation suggests possible structural diversity between IgG subclasses and shows that use of isolated antibody fragments could mask potentially important interactions, owing to molecular flexibility.
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IJS, NUK, SBMB, UL, UM, UPUK
Two dimensional (2D) porous cobalt oxide (Co3O4) nanoflake (CONF) arrays are prepared by a facile sonochemical synthesis followed by calcination at 300 °C for 3 h. The successful synthesis and phase ...purity of CONFs were confirmed using X-ray diffraction (XRD) and Raman spectroscopy. Field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) analyses confirmed the porous flake-like structure of Co3O4. The performance of the CONFs is evaluated for energy storage application. The electrochemical performance in standard three electrode cell system revealed a high redox behaviour of CONFs which reveals its battery grade behaviour. In order to fabricate the supercapattery, CONFs-based electrode is employed as a positive electrode while activated carbon based electrode is used as negative electrode. Supercapattery device showed an excellent performance in terms of specific capacity (108.8C/g), energy density (23.7 Wh/kg) and power density (307 W/kg). The enhanced electrochemical performance was attributed to the unique 2D porous structure of Co3O4. Additionally, supercapattery showed excellent cyclic stability over 2500 cycles by maintaining 88.5% of its initial specific capacity value.
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•Porous Co3O4 nanflakes were prepared by sonochemical method.•Structural and morphological characterizations were done.•Electrochemical performance of Co3O4 nanoflakes was done for energy storage.•Co3O4 nanoflakes based supercapattery gave enhanced electrochemical performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Trends in baseflows based on observed daily streamflow data are evaluated in this study at several sites in the least anthropogenically affected watersheds in the USA. Trends were determined for ...annual maximum, annual mean, and annual median baseflow. Baseflow values derived at 574 stations in the USA for the 44 years from 1970 through 2013 are analyzed using two nonparametric trend tests (Spearman’s rho (SR) test and Mann-Kendall (MK)). Results from the trend tests are compiled for 18 major regions to understand the spatial variability of changes in baseflows across the USA. Results from SR tests indicate that almost half of the stations show statistically significant trends in annual maximum baseflows. Trends in annual median baseflows show that 32.06% of the gauging stations have downward trends, and a total of 56.45% of sites show significant trends for annual mean baseflows. The Souris-Red-Rainy, Missouri, and California watershed regions have a larger number of sites with higher upward trends compared with those from other regions in the USA. The results from the SR test indicate that 262 sites have statistically significant trends in annual maximum baseflow compared with the 254 sites with similar trends noted from the MK test. Based on limited data, it can be concluded that baseflow and precipitation values accumulated for the same month are correlated in some regions. In general, the number of sites with decreasing trends for annual maximum, mean, and median baseflows is larger than the number of sites with increasing trends. Decreasing trends in baseflows are cause for concern and have serious implications on future planning for low flow management strategies for several streams in the USA.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Epoxy/PDMS nanocomposites were prepared using ZnO nanoparticles.•Solution intercalation method has been employed.•NC2 sample shown highest coating resistance (∼1010Ω) for 30 days of immersion.•NC6 ...coating had the highest contact angle as 128°.•Hydrophobicity has been improved noticeably approaching super hydrophobicity.
Epoxy-polydimethylsiloxane (PDMS) nanocomposite coatings loaded with different concentrations (ranged from 2 to 8% (w/w)) of ZnO nanoparticles have been successfully achieved by using the solution intercalation method. In this study, it has been aimed to investigate corrosion protection performance and hydrophobic properties of epoxy/PDMS nanocomposites (NC). Fourier transform infrared (FTIR) spectroscopy was utilized in order to study the chemical structure of the developed coatings. The coating surface wettability was studied by contact angle measurements and the dispersion of ZnO nanoparticles was examined via field emission scanning electron microscope (FESEM). The effects of ZnO nanoparticles on the corrosion resistance and the barrier performance were investigated by electrochemical impedance spectroscopy (EIS). Thermal properties were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) From the FTIR spectra it was observed that the incorporation of nano ZnO particles has demonstrated peak shift and change in intensity. The incorporation of nano ZnO particles within the hybrid polymeric matrix had improved the hydrophobicity in terms of contact angle which reached maximum as 128° for NC6 system. NC2 coating had shown higher coating resistance more than 109Ω even after 30 days of exposure in electrolyte medium. The results obtained from TGA and DSC studies demonstrated that introducing PDMS to epoxy resin increased Tg whereas the incorporation of ZnO nanoparticles in the nanocomposite coatings showed reduction in degradation temperature, cross-linking density of the composite by lowering Tg.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Polymer electrolytes based on poly(vinylidenefluoride-hexafluoropropylene) (PVdF-HFP) as the polymer host, lithium trifluoromethanesulfonate (LiTf) as the salt and ethylene carbonate (EC) as the ...plasticizer, has been prepared by a solution casting technique. Addition of LiTf resulted in an increase in the electrical conductivity of polymer. EC will act to increase the degree of salt dissociation and also ionic mobility. The highest ionic conductivity achieved at room temperature was for PVdF-HFP + LiTf : EC (60 : 40) with the conductivity ∼10
−3
S cm
−1
. The conductivity of the polymer electrolyte increases with the increase in amount of plasticizer. The interaction of the PVdF-HFP, LiTf and EC were analyzed by Fourier transform infared (FTIR). The temperature dependent conductivity, frequency dependent conductivity, dielectric permittivity (
/
) and modulus (
M
/
) studies were carried out. Thermo gravimetric analysis (TGA) reveals that the thermal stability of polymer electrolytes decreases with the increase in EC content.
Polymer electrolytes based on poly(vinylidenefluoride-hexafluoropropylene) (PVdF-HFP), lithium trifluoromethanesulfonate (LiTf) and ethylene carbonate (EC) were prepared. The highest ionic conductivity achieved at room temperature was for PVdF-HFP + LiTf : EC (60 : 40) with the conductivity ∼10
−3
S cm
−1
.
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IJS, KILJ, NUK, UL, UM, UPUK
