Unveiling the Intrinsic Photophysics in Quasi-Two-Dimensional Perovskites.

The two-dimensional (2D) perovskites have drawn intensive attention due to their unique stability and outstanding optoelectronic properties. However, the debate surrounding the spatial phase distribution and band alignment among different 2D phases in the quasi-2D perovskite has created complexities in understanding the carrier dynamics, hindering material and device development. In this study, we employed highly sensitive transient absorption spectroscopy to investigate the carrier dynamics of (BA)2(MA)n-1PbnI3n+1 quasi-2D Ruddlesden-Popper perovskite thin films, nominally prepared as n = 4. We observed the carrier-density-dependent electron and hole transfer dynamics between the 2D and three-dimensional (3D) phases. Under a low carrier density within the linear response range, we successfully resolved three ultrafast processes of both electron and hole transfers, spanning from hundreds of femtoseconds to several picoseconds, tens to hundreds of picoseconds, and hundreds of picoseconds to several nanoseconds, which can be attributed to lateral-epitaxial, partial-epitaxial, and disordered-interface heterostructures between 2D and 3D phases. By considering the interplay among the phase structure, band alignment, and carrier dynamics, we have proposed material synthesis strategies aimed at enhancing the carrier transport. Our results not only provide deep insights into an accurate intrinsic photophysics of quasi-2D perovskites but also inspire advancements in the practical application of these materials.

Insight into the Catalytic Oxidation Mechanism of Hydrogen Isotopes by Pt Clusters Confined by Silicalite-1.

Highly efficient removal of low concentrations of hydrogen isotope gas in air is crucial for the safe operation of nuclear energy plants. Herein, silicalite-1-confined Pt cluster catalysts were used for the catalytic oxidation of hydrogen isotopes, and the related catalytic mechanism was revealed. Increased temperature in direct hydrogen reduction treatment slightly increased the size of Pt clusters from 1.6 nm at 400 °C to 1.8 nm at 600 °C. The catalyst reduced at 600 °C exhibited excellent performance (99%) in hydrogen isotope oxidation at 75 °C, as well as high stability and catalytic efficiency in continuous and intermittent operation for 7200 min. X-ray absorbance spectroscopy confirmed the existence of Pt clusters in the catalysts, and the theoretical results showed that the total net charge was -0.07 e, indicating a slight charge transfer from the zeolite to the Pt atoms. The metal-support interaction thermally stabilized Pt clusters and altered the metal electronic structure, which enhanced the catalytic activity following a hydroperoxyl (OOH)-mediated route. Based on the low reaction temperature, efficient hydrogen conversion rate, and high stability, the silicalite-1-confined Pt cluster catalyst is expected to be used in hydrogen isotope oxidation treatment to achieve nuclear safety.

Unraveling CO adsorption behaviors and its poisoning effects on ZrCo surface.

Theoretical calculations are performed to elucidate the adsorption behaviors and poisoning effects of CO gas on the ZrCo surface, which drastically limits its application in hydrogen isotopic storage. Specifically, the ionic Zr-Co bond on the surface leads to unique CO adsorption structures on different sites. The CO molecule tends to prefer a tilted adsorption configuration on the Co-Co bridge site. The electronic structures, charge distributions, and bonding characteristics are further explored to study the CO adsorption properties, which obey the electron density donation and back-donation mechanism. For different CO coverages, the stepwise adsorption energies of CO increase with the increasing of coverage, reaching the saturated coverage at nCO = 11. Then, the effects of temperature and partial pressure on CO coverage are evaluated using atomic thermodynamics. The computed phase diagram shows that the ZrCo(110) surface has a stable coverage of nCO = 6 at ambient temperature under ultrahigh vacuum conditions. The pre-adsorbed CO molecules lead to the charge redistribution and the d-band center downshift on the surface, which significantly affect hydrogen adsorption and dissociation. Our results provide insights into the poisoning mechanisms of the impurity gas on ZrCo alloys, which can be beneficial for designing high-performance ZrCo-based alloys with improved poisoning tolerance.

Characterization and Application of Guar Gum/Polyvinyl Alcohol-Based Food Packaging Films Containing Betacyanins from Pokeweed (Phytolacca acinosa Roxb.) Berries and Silver Nanoparticles.

Food packaging films were prepared by using guar gum/polyvinyl alcohol (GP) as the film matrix, 2% Ag nanoparticles (AgNPs) as reinforcing filler and antimicrobial agent, and 1%, 2% and 3% pokeweed betacyanins (PB) as the colorant and antioxidant agent. The structures and color-changing, barrier, mechanical, thermal and antioxidant/antibacterial properties of different films were measured. The results show that the PB were pH-sensitive pigments with pink, purple and yellow colors at pH 3-8, pH 9-11 and pH 12, respectively. PB improved the compatibility of guar gum and polyvinyl alcohol through hydrogen bonds. The films with PB showed a color-changing capacity under ammonia vapor and good color stability in chilled storage. AgNPs and PB elevated the barrier capacity of GP film to light, water vapor and oxygen gas. Meanwhile, AgNPs and PB improved the stiffness, thermal stability and antioxidant/antibacterial activity of GP film. The film with AgNPs and 3% PB showed the highest barrier capacity, stiffness, thermal stability and antioxidant/antimicrobial activity. In shrimp spoilage test, the films with AgNPs and 2% and 3% PB indicated shrimp freshness through film color changes. The results reveal the potential use of the prepared films in active and smart packaging.

Effects of Modified Dietary Fiber from Fresh Corn Bracts on Obesity and Intestinal Microbiota in High-Fat-Diet Mice.

The effects of insoluble dietary fiber from fresh corn bracts modified by dynamic high-pressure micro-fluidization (DHPM) on the pathological characteristics of obesity, intestinal microflora distribution and production of short-chain fatty acids in high-fat-diet C57BL/6 mice were evaluated. The results show that the DHPM-modified dietary fiber from fresh corn bracts significantly reduces weight gain, insulin resistance and oxidative damage caused by a high-fat diet, and promotes the production of SCFAs, especially acetic acid, propionic acid and butyric acid. These modified dietary fibers also change the proportion of different types of bacteria in the intestinal microflora of mice, reduce the ratio of Firmicutes and Bacteroidota and promote the proliferation of Bifidobacteriales. Therefore, the DHPM-modified dietary fiber from fresh corn bracts can be used as a good intestinal microbiota regulator to promote intestinal health, thereby achieving the role of preventing and treating obesity.

Chlorogenic Acid from Burdock Roots Ameliorates Oleic Acid-Induced Steatosis in HepG2 Cells through AMPK/ACC/CPT-1 Pathway.

Hepatic steatosis can cause liver dysfunction and cell injury, on which natural functional factors are expected to be an effective approach for long-term intervention. However, the cellular molecular mechanisms are unclear. Chlorogenic acid is a phenolic compound, which can regulate lipid metabolism and is abundant in burdock root. The aim of this study was to investigate the potential molecular mechanism of the effect of chlorogenic acid from burdock root (ACQA) on steatosis in HepG2 cells. In this study, we found that ACQA reduced the number of lipid droplets and lipid levels in oleic acid-treated HepG2 cells. Molecular mechanistic results showed that ACQA enhanced CPT-1 expression by activating AMPK-related signaling pathways, and the concentrations of Ca2+ and cAMP were increased with the intervention of ACQA. In addition, ACQA enhanced the ß-oxidation of fatty acids, reduced alanine transaminase and aspartate transaminase, and inhibited apoptosis in oleic acid-treated HepG2 cells. Our studies elucidate a novel mechanism that ACQA enhances the ß-oxidation of fatty acids through the AMPK/ACC/CPT-1 pathway to protect against steatosis in HepG2 cells, which provides insight into its molecular mechanism as well as intervention strategies for chlorogenic acid against fatty liver diseases.

Ultrasound-Assisted Fermentation to Remove Cadmium from Rice and Its Application.

Rice, which is a major part of the daily diet, is becoming more and more contaminated by cadmium (Cd). This study combined low-intensity ultrasonic waves with the Lactobacillus plantarum fermentation method and optimized this technique by a single-factor and response surface experiment, aiming to solve the practical problems that the current Cd removal methods for rice cannot address, due to the fact that they require a long time (nearly 24 h), which prevents meeting the rice production demands. The described technique required a short time (10 h), and the highest Cd removal reached 67.05 ± 1.38%. Further analysis revealed that the maximum adsorption capacity of Lactobacillus plantarum for Cd increased by nearly 75%, and the equilibrium adsorption capacity increased by almost 30% after the ultrasonic intervention. Additionally, a sensory evaluation and other experiments proved that the properties of the rice noodles prepared from Cd-reduced rice obtained by ultrasound-assisted fermentation were comparable to those of traditional rice noodles, indicating that this method can be used in actual rice production.

Study on physicochemical characteristics of lutein nanoemulsions stabilized by chickpea protein isolate-stevioside complex.

BACKGROUND: Chickpea protein isolate (CPI) originating from chickpeas has the advantages of facilitating the stability of food emulsions. Stevioside (STE) exhibits a notable surface activity and can improve the water solubility of numerous hydrophobic nutrients. STE and protein mixtures show great potential as emulsions stabilizers. The present study aimed to prepare a novel nanoemulsion for encapsulating lutein (LUT) by ultrasonic homogenization using chickpea protein isolate-stevioside complex (CPI-STE) as a stabilizer and also to investigate the physicochemical characteristics. RESULTS: The results obtained showed that different preparation conditions demonstrated significant influences on the physicochemical properties of CPI-STE-LUT nanoemulsions. Under the optimal condition, the average particle size of CPI-STE-LUT nanoemulsions was 195.1 nm, and the emulsifying and encapsulation efficiencies of lutein were 91.04% and 87.56%, respectively. CPI-STE-LUT nanoemulsions stabilized by CPI-STE could significantly increase the emulsifying and encapsulation efficiencies of lutein compared to that stabilized by CPI. Fourier transform infrared spectroscopy revealed that hydrogen bond was the main binding force of CPI and lutein, and there was a covalent bond between the two molecules. Furthermore, the stability of CPI-STE-LUT nanoemulsions in gastrointestinal phase was higher than that of CPI-LUT nanoemulsions, which could load lutein more effectively and be more resistant to digestive enzymes. CONCLUSION: The present study reports the physicochemical characterization of CPI-STE-LUT nanoemulsions for the first time. CPI-STE-LUT nanoemulsions were characterized by a small average particle size lower than 200 nm, as well as high emulsifying and encapsulation efficiencies, and good stability. © 2021 Society of Chemical Industry.

Effect of Hf doping on He behavior in tritium storage material ZrCo.

An exhaustive analysis based on density functional theory (DFT) simulations of the effect of Hf doping on helium behavior has been performed in ZrCo. The He impurities have been placed both at interstitial positions and substitutional positions from the first nearest neighbor (1nn) of the Hf atom to the sixth nearest neighbor (6nn). In such areas, the electronic charge density is different, and therefore the formation and diffusion of He atoms vary in the surrounding of the Hf atom. The results show that Hf doping reduces the volume of the interstitial sites nearby, resulting in the weakening ability of the interstitial sites to accommodate He atoms. According to the results of formation energy, whether it is the substitutional He or the interstitial He atom, the formation is not only related to the distance of Hf, but more importantly, it is closely related to the unit cell where the He atom is located. In addition, Hf atoms promote the capture of He atoms by vacancies nearby and the migration of He atoms between the tetrahedral positions. The result also validates the well-known knowledge of vacancies as efficient sinks for He atoms in ZrCo. From the lower and lower migration energetic barriers along 3nn → 2nn → 1nn → 1nn pathways, we can infer an increasing mobility of the He atom from 3nn to 1nn. This situation could favor their accumulation surrounding an Hf atom, improving the ability of helium retention. These findings provide really indisputable evidence that the Hf dopant makes a difference in the behavior of He atoms in bulk ZrCo. Therefore, a ZrCo system with Hf doping can be considered as a good candidate for tritium storage material in a future nuclear fusion reactor.

Activation and Disproportionation of Zr2Fe Alloy as Hydrogen Storage Material.

As a hydrogen storage material, Zr2Fe alloy has many advantages such as fast hydrogen absorption speed, high tritium recovery efficiency, strong anti-pulverization ability, and difficulty self-igniting in air. Zr2Fe alloy has lower hydrogen absorption pressure at room temperature than LaNi5 alloy. Compared with the ZrVFe alloy, the hydrogen release temperature of Zr2Fe is lower so that the material can recover hydrogen isotopes at lower hydrogen concentration efficiently. Unfortunately, the main problem of Zr2Fe alloy in application is that a disproportionation reaction is easy to occur after hydrogen absorption at high temperature. At present, there is little research on the generation and influencing factors of a disproportionation reaction in Zr2Fe alloy. In this paper, the effects of temperature and hydrogen pressure on the disproportionation of Zr2Fe alloy were studied systematically. The specific activation conditions and experimental parameters for reducing alloy disproportionation are given, which provide a reference for the specific application of Zr2Fe alloy.

Electric Properties of Molecule Zr2Fe Based on the Full Relativistic Theory.

The present work is devoted to the study of the electric properties: electric dipole moment, electric quadrupole moment, electric field gradients and electric dipole polarizability of molecule Zr2Fe on base of the full relativistic theory with basis set 3⁻21G. The electric dipole moment of Zr2Fe is symmetrical to the axis of C 2 V -the vector sum of two projections for two chemical bond FeZr (3.2883 Å), based on when there is charge distribution. The force constant k 2 is directly connected with electric field gradients.

Effect of exogenous spermine on chilling injury and antioxidant defense system of immature vegetable soybean during cold storage.

The effect of exogenous spermine on chilling injury (CI) and antioxidant defense system of immature vegetable soybean (Glycine max L.) during cold storage were investigated. Freshly harvested immature soybeans were treated with 0.8 mmol/L spermine at room temperature for 20 min and then stored at 5 ± 1 °C or 1 ± 1 °C and 85-95% relative humidity for up to 60 days. Results showed that exogenous spermine alleviated the CI, delayed the gradual decreasing activities of superoxide dismutase (SOD) and catalase, and maintained a favourable balance in reactive oxygen species levels at storage period. Although cold temperature (1 ± 1 °C) inhibited the synthesis of l-(malonylamino)-cyclopropane-l-carboxylic acid (MACC), raised ethylene production, and resulted in membrane damage, exogenous spermine obviously hindered the accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC). It was concluded that exogenous spermine alleviated CI of cold-stored immature soybeans through regulating the antioxidant system and ACC metabolism.

Effect of starch osmo-coating on carotenoids, colour and microstructure of dehydrated pumpkin slices.

Carotenoids in pumpkins are extremely unstable during industrial drying, to avoid the carotenoid degradation, starch omso-coating was subjected to the pretreatment process for dehydrated pumpkin slices. The results showed that starch omso-coating reduced the dehydration rate of pumpkin slices. When coated with corn starch, the retention rates of lutein, α-carotene and ß-carotene in dehydrated pumpkin slices significantly increased by 11.3, 9.0 and 7.7%, respectively, and the provitamin A activity increased by 9.5%. 1% (w/v) modified corn omso-coating gave highest retention rate of total carotenoids (95.5%), while provitamin A activity reached 4148 µg RAE/100 g. In addition, the colour parameters △E and a* values reduced, but L*, b* and H values increased with coated samples. Pearson correlation analysis showed that lutein, α-carotene and ß-carotene were significantly positive correlated with L*, and exhibited negative correlations with △E. The SEM indicated starch granules was attached to tissue gap and caused the film formation of oxygen barrier. It could be concluded that modified corn coating effectively improved the quality of final product.

Delivery of Lutein by Using Modified Burdock Polysaccharide Aggregates: Preparation, Characterization, and In Vitro Release Properties.

Novel self-assembled aggregates of stearic acid (SA)-modified burdock polysaccharide (BP) for loading lutein were constructed, and the release and absorption properties of lutein in the aggregates in simulated gastrointestinal fluid were investigated. Three different degrees of substitution (DS) of SA-BPs were used to embed lutein, resulting in the encapsulation efficiency exceeding 90%. The aggregates were uniformly spherical, with a particle size range of 227-341 nm. XRD analysis revealed that lutein was present in a non-crystalline state within the aggregates. FT-IR and FS analysis demonstrated that lutein was located in the hydrophobic domains of SA-BP. The highest bioavailability of lutein in these aggregates reached 4.36 times that in the unmodified samples. These aggregates were able to remain stable in gastric juice and enhance the release rate of lutein in intestinal fluid. The transport of lutein-loaded SA-BP aggregates in Caco-2 cells competed with P-glycoprotein inhibitors, mainly promoting the transmembrane absorption of lutein through caveolae (or lipid raft)-related and clathrin-dependent endocytosis pathways. The above results suggest that SA-BP aggregates have the potential to be promising carriers for the efficient delivery of hydrophobic lutein.

Solubility-permeability interplay of a supersaturated lutein delivery system constructed by glycosylated stevioside and hydroxypropyl-methylcellulose.

This study investigated the solubilizing capacity of glycosylated stevioside/hydroxypropyl-methylcellulose (stevia-G-HPMC) complexes with varying mass ratios on lutein. The impact on the steady-state flux and permeability coefficient of intracellular lutein was also explored through the construction of a Caco-2 cellular transport model. The results indicated that the equilibrium solubility of lutein linearly increased with an increase in stevia-G amount. The stability constants of the ternary system surpassed those of the binary system. Molecular dynamics simulation revealed a tight and stable structure in lutein supersaturated complexes. Meanwhile, lutein-stevia-G-HPMC complexes demonstrated superior cumulative penetrations, with the peak Papp (AP â†’ BL) value being (3.24 ± 0.89) × 10-5 cm·s-1. There was a slight decrease in Papp (BL â†’ AP), which improved the forward transport of lutein. Highly soluble lutein in aqueous environments saturated the extracellular transport proteins on the AP side of cell membranes, thereby maintaining the high permeability transport. Notably, the permeability trend of lutein in Caco-2 cells negatively correlated with the equilibrium solubility and matched the single exponential growth model. When the mass ratio of lutein, stevia-G and HPMC was 1:21:5, the solubility-permeability trade-off of lutein was effectively maintained.

Isotope engineering achieved by local coordination design in Ti-Pd co-doped ZrCo-based alloys.

Deuterium/Tritium (D/T) handling in defined proportions are pivotal to maintain steady-state operation for fusion reactors. However, the hydrogen isotope effect in metal-hydrogen systems always disturbs precise D/T ratio control. Here, we reveal the dominance of kinetic isotope effect during desorption. To reconcile the thermodynamic stability and isotope effect, we demonstrate a quantitative indicator of Tgap and further a local coordination design strategy that comprises thermodynamic destabilization with vibration enhancement of interstitial isotopes for isotope engineering. Based on theoretical screening analysis, an optimized Ti-Pd co-doped Zr0.8Ti0.2Co0.8Pd0.2 alloy is designed and prepared. Compared to ZrCo alloy, the optimal alloy enables consistent isotope delivery together with a three-fold lower Tgap, a five-fold lower energy barrier difference, a one-third lower isotopic composition deviation during desorption and an over two-fold higher cycling capacity. This work provides insights into the interaction between alloy and hydrogen isotopes, thus opening up feasible approaches to support high-performance fusion reactors.

Large-Scale Integration of the Ion-Reinforced Phytic Acid Layer Stabilizing Magnesium Metal Anode.

Rechargeable magnesium batteries (RMBs) have garnered significant attention for their potential in large-scale energy storage applications. However, the commercial development of RMBs has been severely hampered by the rapid failure of large-sized Mg metal anodes, especially under fast and deep cycling conditions. Herein, a concept proof involving a large-scale ion-reinforced phytic acid (PA) layer (100 cm × 7.5 cm) with an excellent water-oxygen tolerance, high Mg2+ conductivity, and favorable electrochemical stability is proposed to enable rapid and uniform plating/stripping of Mg metal anode. Guided by even distributions of Mg2+ flux and electric field, the as-prepared large-sized PA-Al@Mg electrode (5.8 cm × 4.5 cm) exhibits no perforation and uniform Mg plating/stripping after cycling. Consequently, an ultralong lifespan (2400 h at 3 mA cm-2 with 1 mAh cm-2) and high current tolerance (300 h at 9 mA cm-2 with 1 mAh cm-2) of the symmetric cell using the PA-Al@Mg anode could be achieved. Notably, the PA-Al@Mg//Mo6S8 full cell demonstrates exceptional stability, operating for 8000 cycles at 5 C with a capacity retention of 99.8%, surpassing that of bare Mg (3000 cycles, 74.7%). Moreover, a large-sized PA-Al@Mg anode successfully contributes to the stable pouch cell (200 and 750 cycles at 0.1 and 1 C), further confirming its significant potential for practical utilization. This work provides valuable theoretical insights and technological support for the practical implementation of RMBs.

First-Principles Study of Nitrogen Adsorption and Dissociation on ZrMnFe(110) Surface.

The adsorption, dissociation and penetration processes of N2 on the surface of ZrMnFe(110) were investigated using the first-principles calculation method in this paper. The results indicate that the vacancy Hollow 1 composed of 4Zr1Fe on the surface of ZrMnFe(110) is the best adsorption site for the N2 molecule and N atom, and the adsorption energies are 10.215 eV and 6.057 eV, respectively. Electron structure analysis indicates that the N2 molecule and N atoms adsorbed mainly interact with Zr atoms on the surface. The transition state calculation shows that the maximum energy barriers to be overcome for the N2 molecule and N atom on the ZrMnFe(110) surface were 1.129 eV and 0.766 eV, respectively. This study provides fundamental insight into the nitriding mechanism of nitrogen molecules in ZrMnFe.

Improvement of Hot Tearing Resistance of AZ91 Alloy with the Addition of Trace Ca.

Hot tearing is the most common and serious casting defect that restricts the light weight and integration of magnesium alloy components. In the present study, trace Ca (0-1.0 wt.%) was added to improve the resistance of AZ91 alloy to hot tearing. The hot tearing susceptivity (HTS) of alloys was experimentally measured by a constraint rod casting method. The results indicate that the HTS presents a ν-shaped tendency with the increase in Ca content, and reaches its minimum value in AZ91-0.1Ca alloy. Ca is well dissolved into α-Mg matrix and Mg17Al12 phase at an addition not exceeding 0.1 wt.%. The solid-solution behavior of Ca increases eutectic content and its corresponding liquid film thickness, improves the strength of dendrites at high temperature, and thereby promotes the hot tearing resistance of the alloy. Al2Ca phases appear and aggregate at dendrite boundaries with further increases in Ca above 0.1 wt.%. The coarsened Al2Ca phase hinders the feeding channel and causes stress concentration during the solidification shrinkage, thereby deteriorating the hot tearing resistance of the alloy. These findings were further verified by fracture morphology observations and microscopic strain analysis near the fracture surface based on kernel average misorientation (KAM).

Identification of carotenoids from fruits and vegetables with or without saponification and evaluation of their antioxidant activities.

This study investigates the composition and form of carotenoids in typical fruits and vegetables obtained through saponification or non-saponification and evaluates the correlation between carotenoids and antioxidant capacity. The results showed that the content of the total carotenoids in non-saponified broccoli was the highest, reaching 1505.93 ± 71.99 µg/g d.w. The content of the total carotenoids in pumpkin flesh and broccoli after saponification was reduced by 71.82% and 52.02%, respectively. The content of lutein in spinach decreased by 24.4% after saponification, but the content of ß-carotene increased compared to non-saponification. After saponification, the total antioxidant activities of apple peel, radish peel, radish flesh, and maize were significantly increased by 30.26%, 91.74%, 425.30%, and 242.88%, respectively. Saponification also improved the antioxidant activities of carotenoids in maize under six different antioxidant assays. The highest correlation was found between the total amount of carotenoids and oxygen radical absorbance capacity (R = 0.945), whereas the correlation coefficients among reducing power, 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid), hydroxyl and superoxide radical scavenging activity, and total carotenoids' content were 0.935, 0.851, 0.872, 0.885, and 0.777, respectively, all showing significant correlations. The study demonstrates that saponification can increase the total carotenoid content and antioxidation for apple peel, radish peel, radish flesh, and maize. Moreover, carotenoids were significantly positively correlated with most in vitro antioxidant assays. This study provides a theoretical basis for improving the postharvest added value of fruits and vegetables and rationally utilizing their byproducts.