Reversible cross-linking facilitates the formation of critical nucleus in binary polymer blends.

Using self-consistent field theory, we study the effect of reversible cross-linking on the nucleation behavior of a binary polymer blend where only one of the components is able to form cross-links. To control the total number of cross-links and their distribution, we introduce a position-dependent cross-linking probability function that is characterized mainly by two parameters, the magnitude and the width. In the weakly cross-linked region, where the product of the magnitude and width, I, is small, the nucleation behavior is classical-like and the profile of the free energy excess is unimodal. In contrast, in the strongly cross-linked region, the profile of the free energy excess becomes bimodal, and the free energy minimum specifies a metastable nucleus. In a certain I, the free energy barrier for the metastable nucleus turns to be negative, which means it becomes more stable. In both cases, the free energy barrier of the critical nucleus is lower than that without cross-linking, indicating that cross-linking always facilitates nucleation although the dynamic behavior may be different when a metastable nucleus is involved during the nucleation process. The free energy analysis demonstrates that the interaction energy rather than the entropy is responsible for the properties of the critical nucleus. Our study provides an easy alternative way for the control of the nucleation behavior and may attract practical interest.

Extracellular Metabolites of Heterotrophic Auxenochlorella protothecoides: A New Source of Bio-Stimulants for Higher Plants.

The biodiversity of microalgal species is enormous, and their versatile metabolism produces a wide diversity of compounds that can be used in food, healthcare, and other applications. Microalgae are also a potential source of bio-stimulants that enhance nutrition efficiency, abiotic stress tolerance, and/or crop quality traits. In this study, the extracellular metabolites of Auxenochlorella protothecoides (EAp) were prepared using three different culture strategies, and their effects on plant growth were examined. Furthermore, the composition of EAp was analyzed by GC-MS. The elongation of lateral roots and the cold-tolerance of Arabidopsis thaliana and Nicotiana benthamiana were promoted by EAp. Moreover, EAp from high-cell-density fermentation stimulated the growth of the leafy vegetables Brassica rapa and Lactuca sativa at dilutions as high as 500- and 1000-fold. Three major groups of compounds were identified by GC-MS, including organic acids or organic acid esters, phenols, and saccharides. Some of these compounds have known plant-stimulating effects, while the rest requires further investigation in the future. Our study demonstrates that EAp is a potential bio-stimulant, while also providing an environmentally friendly and economical microalgae fermentation process.

Mesenchymal Stem Cell-Derived Exosomes Attenuate Murine Cytomegalovirus-Infected Pneumonia via NF-κB/NLRP3 Signaling Pathway.

Reactivation and infection with cytomegalovirus (CMV) are frequently observed in recipients of solid organ transplants, bone marrow transplants, and individuals with HIV infection. This presents an increasing risk of allograft rejection, opportunistic infection, graft failure, and patient mortality. Among immunocompromised hosts, interstitial pneumonia is the most critical clinical manifestation of CMV infection. Recent studies have demonstrated the potential therapeutic benefits of exosomes derived from mesenchymal stem cells (MSC-exos) in preclinical models of acute lung injury, including pneumonia, ARDS, and sepsis. However, the role of MSC-exos in the pathogenesis of infectious viral diseases, such as CMV pneumonia, remains unclear. In a mouse model of murine CMV-induced pneumonia, we observed that intravenous administration of mouse MSC (mMSC)-exos reduced lung damage, decreased the hyperinflammatory response, and shifted macrophage polarization from the M1 to the M2 phenotype. Treatment with mMSC-exos also significantly reduced the infiltration of inflammatory cells and pulmonary fibrosis. Furthermore, in vitro studies revealed that mMSC-exos reversed the hyperinflammatory phenotype of bone marrow-derived macrophages infected with murine CMV. Mechanistically, mMSC-exos treatment decreased activation of the NF-κB/NLRP3 signaling pathway both in vivo and in vitro. In summary, our findings indicate that mMSC-exo treatment is effective in severe CMV pneumonia by reducing lung inflammation and fibrosis through the NF-κB/NLRP3 signaling pathway, thus providing promising therapeutic potential for clinical CMV infection.

Kondo scattering in underdoped Nd1-xSrxNiO2 infinite-layer superconducting thin films.

The recent discovery of superconductivity in infinite-layer nickelates generates tremendous research endeavors, but the ground state of their parent compounds is still under debate. Here, we report experimental evidence for the dominant role of Kondo scattering in the underdoped Nd1-xSrxNiO2 thin films. A resistivity minimum associated with logarithmic temperature dependence in both longitudinal and Hall resistivities are observed in the underdoped Nd1-xSrxNiO2 samples before the superconducting transition. At lower temperatures down to 0.04 K, the resistivities become saturated, following the prediction of the Kondo model. A linear scaling behavior [Formula: see text] between anomalous Hall conductivity [Formula: see text] and conductivity [Formula: see text]is revealed, verifying the dominant Kondo scattering at low temperature. The effect of weak (anti-)localization is found to be secondary. Our experiments can help in clarifying the basic physics in the underdoped Nd1-xSrxNiO2 infinite-layer thin films.

Combination of zinc and selenium alleviates ochratoxin A-induced fibrosis via blocking ROS-dependent autophagy in HK-2 cells.

BACKGROUND: Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium. The key target organ of OTA toxicity is the kidney, which has a significant impact on human health. Recently, nutrition regulation is suggested to be an effective protection against mycotoxins contamination. The current study investigated the combined protective effects of zinc and selenomethionine (SeMet) (a major component of organic selenium) on OTA-induced renal fibrosis and their potential mechanisms in human renal proximal tubule epithelial cells (HK-2 cells). METHODS: Cytotoxicity of different concentrations of OTA, zinc and SeMet on HK-2 cells was detected by cell viability, lactate dehydrogenase (LDH) and apoptotic nuclei assays. The expression of fibrosis biomarkers was detected by Real-Time PCR, western blotting and indirect immunofluorescence assays. The production of reactive oxygen species (ROS) was detected by ROS assay kit. The protein expression of autophagy biomarkers was detected by western blotting assay. RESULTS: Cytotoxicity was induced by OTA treatment in a dose-dependent manner, and it was attenuated by zinc or SeMet application in HK-2 cells. Zinc or SeMet application also down-regulated the expression of fibrosis biomarkers, and the combination of them displayed better effects. In addition, OTA increased intracellular ROS level and activated autophagy in a dose-dependent manner, and it was reversed by zinc and SeMet combined application. With the treatment of hydrogen peroxide (H2O2) or rapamycin (the specific activator of autophagy), the combined protective effects of zinc and SeMet were abolished. CONCLUSIONS: Zinc and SeMet application alleviated OTA-induced cytotoxicity and fibrosis in HK-2 cells. Combination of them was more effective than its individual application. The present study manifest novel insight about the alleviation of OTA-induced nephrotoxicity by nutrition regulation, and had a guiding effect on the clinical supplementation of nutritional elements.

Physicochemical properties and digestion mechanism of starch-linoleic acid complex induced by multi-frequency power ultrasound.

The effects of multi-frequencies (mono: 20 kHz, 40 kHz, 60 kHz; dual: 20/40 kHz, 40/60 kHz, 20/60 kHz, and tri: 20/40/60 kHz) on physicochemical properties and in vitro digestibility of arrowhead starch-linoleic acid (AS-LA) complexes were evaluated. The complexing index and FTIR analyses showed that sonication treatment might be helpful in the formation of AS-LA complexes in an ultrasound frequency-dependent manner. The SEM micrographs revealed that the various ultrasonication frequencies caused dense network structure in AS-LA complexes. The XRD showed a V-type crystalline structure with increased crystallinity. Compared with arrowhead starch, a decrease in rapidly digestible starch , and an increase in resistant starch contents of AS-LA under various ultrasound frequencies was due to arrowhead starch and linoleic acid molecular interactions, which inhibited the further binding abilities. As a non-thermal technology, ultrasound could be effectively employed to prepare starch-lipid complexes with significant potential in functional foods and drug delivery systems.

Influence of Small-Scale Correlation on the Interface Evolution of Semiflexible Homopolymer Blends.

Within the framework of a dynamic self-consistent field theory, we study the effect of the correlations in a small scale on polymer dynamics, adopting the semiflexible homopolymer blends as the model system. This is accomplished by taking the pair correlation function of ideal semiflexible chains as the Onsager coefficient and the Debye function as an approximation to the Onsager coefficient. Relying on the difference of the two pair correlation functions in the small-scale region, we can identify the effect of small-scale correlations. In the equilibrium state, with the chain length growing, the interface width has a continuous transition from the contour length to radius of gyration. The investigation of interfacial evolution and chain orientation reveals that strong small-scale correlations would accelerate the small-scale dynamic process. We also expect that such a small-scale effect should be highlighted in the process where microscopic phase separation happens.

Large linear magnetoresistance caused by disorder in WTe2- δ thin film.

Weyl semimetal WTe2 has attracted considerable attention owing to its extremely large, unsaturated and quadratic magnetoresistance. Here, we study the magnetotransport properties of WTe2-δ thin film, which shows an unsaturated and linear magnetoresistance of up to ∼1650%. A more complex and accurate method, known as the maximum entropy mobility spectrum, is used to analyze the mobility and density of carriers. The results show that linear magnetoresistance can be explained by the classical disorder model because the slope of linear magnetoresistance and the crossover field are proportional to the mobility and inverse mobility, respectively. Furthermore, the validity of the maximum entropy mobility spectrum is validated by the Shubnikov-de Haas oscillations. Moreover, at low temperature, we determined that the unsaturated and near-quadratic magnetoresistance in the WTe1.93 thin film can be explained by charge compensation. Note that the electron-hole compensation is broken in the WTe1.42 thin film, which indicates that the carrier scattering induced by the disorder may suppress the charge compensation in the WTe2 sample with defects/dopants. To summarize, the discovery of disorder-induced linear magnetoresistance allows us to explain different magnetoresistance behaviors of WTe2.

Fabrication of an Inexpensive Hydrophilic Bridge on a Carbon Substrate and Loading Vanadium Sulfides for Flexible Aqueous Zinc-Ion Batteries.

Coupling electrode materials with carbon substrates to construct flexible aqueous Zn-ion batteries (ZIBs) with excellent electrochemical performance is an attractive research focus. However, further improving the Zn2+/electron diffusion kinetics in such systems is still desirable. Herein, we present a novel hydrophilic carbon substrate that employs acid-treated natural halloysite and carbon nanotubes for the first time as structural and interfacial modifiers for loading V3S4 as a composite cathode (denoted as HCC-V3S4) for flexible ZIBs. The devices exhibit a high specific capacity of 148 mA h·g-1 under a current density of 0.5 A·g-1 (95% retention after 200 cycles), excellent rate performance, and a high energy density of 155.7 W h·kg-1, together with a high-power density of 5000 W·kg-1. The promising electrochemical property can be associated with the formation of the hydrophilic surface/interface and with the good conductivity of the composite electrode, which increases the Zn2+/electron transmission rate. Owing to the cost-effective design of the flexible substrate and the ZIB's impressive electrochemical performance, the fabricated device shows good potential applications in portable and wearable electronics.

Effects of frequency ultrasound on the properties of zein-chitosan complex coacervation for resveratrol encapsulation.

In this study, resveratrol was successfully encapsulated using zein-chitosan complex coacervation. The encapsulation efficiency was markedly improved (51.4%) after chitosan coating at 1:2.5 zein/chitosan ratio, compared with 38.6% using native zein. Analysis of multi-model frequency ultrasound treatment effects on resveratrol encapsulation using zein-chitosan complex coacervation showed that 28/40 kHz dual-frequency ultrasound led to the highest encapsulation efficiency (65.2%; 31.9% increase) and loading capacity (5.9%; 31.1% increase) of resveratrol, followed by multi-frequency ultrasound at 20/28/40 kHz (17.8% encapsulation efficiency increase; 17.8% loading capacity increase). Dual-frequency ultrasound treatment significantly reduced the zein-chitosan complex coacervation particle size and reduced their distribution, however, did not change the zeta potential. Fourier transform infrared spectroscopy and fluorescence spectroscopy analysis demonstrated that ultrasound treatment had no effect on secondary structure of zein-chitosan complex but markedly decreased the fluorescence emission intensity. Differential scanning calorimetry and X-ray diffraction results indicated that Dual-frequency ultrasound treatment improved the thermal stability of zein-chitosan complex coacervation but had no effect on the crystal structure. Atomic force microscopy and scanning electron microscopy images revealed uniform distribution of zein-chitosan complex coacervation followed by ultrasonic treatment.

Gambogic acid induces apoptosis by regulating the expression of Bax and Bcl-2 and enhancing caspase-3 activity in human malignant melanoma A375 cells.

OBJECTIVES: To investigate the effect of a Chinese traditional medicine, gambogic acid (GA), on human malignant melanoma (MM) A375 cells and to study the mechanism of apoptosis induced by GA. METHODS: A375 cells were treated with GA at different doses and for different times, and their proliferation and viability were detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induced by GA in A375 cells was observed by annexin-V/propidium iodide doubling staining flow cytometry assay and Hoechst staining. To further determine the molecular mechanism of apoptosis induced by GA, the changes in expression of Bcl-2 and Bax were detected by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot, and caspase-3 activity was measured by fluorescence resonance energy transfer (FRET) probe. RESULTS: After incubation with GA, A375 cell proliferation was dramatically inhibited in a dose-dependent manner. After these cells had been exposed to GA for 24, 36 and 48 h, the IC(50) values were 1.57 +/- 0.05, 1.31 +/- 0.20, and 1.12 +/- 0.19 microg/mL, respectively. Treatment of A375 cells with GA (2.5-7.5 microg/mL) for 36 h resulted in an increased number of early apoptotic cells, which ranged from 27.6% to 41.9%, in a dose-dependent manner, compared with only 3.5% apoptotic cells in the non-GA-treated group. An increase in Bax and decrease in Bcl-2 expression were found by real-time RT-PCR and Western blot. Caspase-3 activity was increased in a dose-dependent manner, observed by FRET probe. CONCLUSION: GA can inhibit the proliferation of A375 cells and induce their apoptosis, which may be related to the up-regulation of the Bax/Bcl-2 ratio and caspase-3 activity.