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"Liu, Pan-pan"
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Zeolite-confined subnanometric PtSn mimicking mortise-and-tenon joinery for catalytic propane dehydrogenation
Heterogeneous catalysts are often composite materials synthesized via several steps of chemical transformation, and thus the atomic structure in composite is a black-box. Herein with machine-learning-based atomic simulation we explore millions of structures for MFI zeolite encapsulated PtSn catalyst, demonstrating that the machine-learning enhanced large-scale potential energy surface scan offers a unique route to connect the thermodynamics and kinetics within catalysts’ preparation procedure. The functionalities of the two stages in catalyst preparation are now clarified, namely, the oxidative clustering and the reductive transformation, which form separated Sn
4
O
4
and PtSn alloy clusters in MFI. These confined clusters have high thermal stability at the intersection voids of MFI because of the formation of “Mortise-and-tenon Joinery”. Among, the PtSn clusters with high Pt:Sn ratios (>1:1) are active for propane dehydrogenation to propene, ∼10
3
in turnover-of-frequency greater than conventional Pt
3
Sn metal. Key recipes to optimize zeolite-confined metal catalysts are predicted.
The atomic structure of heterogeneous catalysts is usually a blackbox. Here the authors demonstrate large-scale machine learning atomic simulations help to resolve the catalyst structure and reaction mechanism of encapsulated PtSnO
x
clusters in zeolite that feature a mortise-and-tenon joinery structure and the superior activity towards propane dehydrogenation.
Journal Article
طلاق على الطريقة الصينية /
تقدم هذه الرواية صورة عن قرب للسياسة المحلية التي هي المحرك لكل شيء في الصين» هكذا كتبت نيويورك تايمز عن رواية \"طلاق على الطريقة الصينية\"، فيما وصفة الرواية حسب kirkus reviews بأنها : «حكاية بارعة تجعلك تضحك حتى وأنت مبتئس، إنها ببساطة هجاء خفي ماكر». بينما يقر المترجم الأمريكي الشهير هاوارد جولدبلات بأن ليو كتب «قصة بارعة ستجعلك تضحك وتبكي. كلماته بسيطة لكنها ستظل باقية في ذاكرتك لفترة طويلة بعد أن تنتهي من قراءتها». \"طلاق على الطريقة الصينية\"، رواية ساخرة ولاذعة وتهكمية. أثارت ضجة كبيرة في الصين حين صدروها، وترجمت إلى 34 لغة، كما تحولت إلى فيلم سينمائي، أثار بدوره هو الآخر ضجة كبيرة سببها الطابع السياسي الذي يحمله النص الأصلي.
BOOK
The non-structural protein of SFTSV activates NLRP1 and CARD8 inflammasome through disrupting the DPP9-mediated ternary complex
Inflammasomes function as immune-signaling platforms that were assembled following detection of pathogens. NLRP1 and CARD8 are related inflammasomes that use their C-terminal (CT) fragments containing a caspase recruitment domain (CARD) and the UPA domain to initiate the inflammasome. At rest, dipeptidyl peptidases 8 and 9 (DPP8/9) inhibit inflammatory CT by interacting with the function-to-find domain (FIIND) of NLRP1/CARD8 and forming an inhibitory NLRP1/CARD8-DPP9 ternary complex consisting of DPP9, full-length NLRP1/CARD8, and NLRP1/CARD8 CT. However, the specific triggers of NLRP1 and CARD8 have not yet been fully identified. Here, we report that a tick-borne bunyavirus SFTSV infection activates the NLRP1 inflammasome in primary keratinocytes and the CARD8 inflammasome in macrophages in a similar manner by targeting the ternary inhibitory complex, respectively. Mechanistically, SFTSV NSs interact with NLRP1 and CARD8 via their FIIND domains, suggesting that DPP8/9 are likely to compete for binding; on the other hand, NSs promote the degradation of DPP8 and DPP9. Both contribute to more efficient destabilization of the DPP8/9 ternary complex and release the activated CT. Moreover, CARD8 deletion promotes SFTSV replication. In conclusion, we found a novel mechanism of viral protein activation of NLRP1 and CARD8 by disrupting the DPP9-binding checkpoint.
Journal Article
Shear-induced assembly of a transient yet highly stretchable hydrogel based on pseudopolyrotaxanes
Dissipative self-assembly is common in biological systems, where it serves to maintain a far-from-equilibrium functional state through fuel consumption. Synthetic dissipative systems have been prepared that can mimic some of the properties of biological systems, but they often show poor mechanical performance. Here, we report a shear-induced transient hydrogel that is highly stretchable. The system is constructed by adding Cu(
ii
) into the aqueous solution of a pseudopolyrotaxane, which is itself formed by threading molecular tubes on polyethylene glycol chains. Vigorous shaking transforms the solution into a gel, which gradually relaxes back to the sol state over time. This cycle can be repeated at least five times. A mechanism is proposed that relies on a shear-induced transition from intrachain to interchain coordination and subsequent thermal relaxation. The far-from-equilibrium hydrogel is highly stretchable, which is probably due to ‘frictional’ sliding of the molecular tubes on the polyethylene glycol chains. On shaking, the hydrogel undergoes fast self-healing.
Synthetic dissipative systems, formed by out-of-equilibrium self-assembly processes, can mimic some of the properties of biological systems, but often show poor mechanical performance. Now, a shear-induced transient hydrogel has been prepared that is also highly stretchable. The system is based on coordination interactions between Cu(
ii
) centres and the pendant carboxylate groups of a pseudopolyrotaxane.
Journal Article
Regulation of stem-like cancer cells by glutamine through β-catenin pathway mediated by redox signaling
Background
Cancer stem cells (CSCs) are thought to play an important role in tumor recurrence and drug resistance, and present a major challenge in cancer therapy. The tumor microenvironment such as growth factors, nutrients and oxygen affect CSC generation and proliferation by providing the necessary energy sources and growth signals. The side population (SP) analysis has been used to detect the stem-like cancer cell populations based on their high expression of ABCG2 that exports Hoechst-33342 and certain cytotoxic drugs from the cells. The purpose of this research is to investigate the effect of a main nutrient molecule, glutamine, on SP cells and the possible underlying mechanism(s).
Methods
Biochemical assays and flow cytometric analysis were used to evaluate the effect of glutamine on stem-like side population cells in vitro. Molecular analyses including RNAi interfering, qRT-PCR, and immunoblotting were employed to investigate the molecular signaling in response to glutamine deprivation and its influence on tumor formation capacity in vivo.
Results
We show that glutamine supports the maintenance of the stem cell phenotype by promoting glutathione synthesis and thus maintaining redox balance for SP cells. A deprivation of glutamine in the culture medium significantly reduced the proportion of SP cells. L-asparaginase, an enzyme that catalyzes the hydrolysis of asparagine and glutamine to aspartic acid and glutamate, respectively, mimics the effect of glutamine withdrawal and also diminished the proportion of SP cells. Mechanistically, glutamine deprivation increases intracellular ROS levels, leading to down-regulation of the β-catenin pathway.
Conclusion
Glutamine plays a significant role in maintaining the stemness of cancer cells by a redox-mediated mechanism mediated by β-catenin. Inhibition of glutamine metabolism or deprivation of glutamine by L-asparaginase may be a new strategy to eliminate CSCs and overcome drug resistance.
Journal Article
Advances in photobiomodulation for cognitive improvement by near-infrared derived multiple strategies
Cognitive function is an important ability of the brain, but cognitive dysfunction can easily develop once the brain is injured in various neuropathological conditions or diseases. Photobiomodulation therapy is a type of noninvasive physical therapy that is gradually emerging in the field of neuroscience. Transcranial photobiomodulation has been commonly used to regulate neural activity in the superficial cortex. To stimulate deeper brain activity, advanced photobiomodulation techniques in conjunction with photosensitive nanoparticles have been developed. This review addresses the mechanisms of photobiomodulation on neurons and neural networks and discusses the advantages, disadvantages and potential applications of photobiomodulation alone or in combination with photosensitive nanoparticles. Photobiomodulation and its associated strategies may provide new breakthrough treatments for cognitive improvement.
Journal Article
Flavor characteristics and chemical compositions of oolong tea processed using different semi-fermentation times
Flavor characteristics and chemical compositions of Tieguanyin oolong tea processed using different semi-fermentation times were investigated. Six flavor attributes of the teas, namely, astringency, bitterness, umami, sweet aftertaste, floral flavor, and green fruity flavor, were analysed. With extended semi-fermentation time, the taste intensity of sweet aftertaste increased, and the aroma intensity of floral and green fruity flavors increased, while the intensities of astringency, bitterness, and umami showed no clear trend. With increasing semi-fermentation time, the concentrations of gallated catechins, myricetin-rhamnose, quercetin-rutinoside, myricetin, and theanine greatly decreased, while those of total theaflavins, vitexin-rhamnose, kaempferol-galactose, kaempferol-rutinoside, vitexin, quercetin, and kaempferol increased significantly. The intensity of bitter taste was positively correlated with the concentrations of total catechins and gallated catechins. The intensity of astringent taste strongly correlated with the flavonoid concentrations, and that of sweet aftertaste positively correlated with the concentrations of (−)-epigallocatechin and (−)-epicatechin. However, dose-over-threshold analysis revealed that catechins, theaflavin, flavonol glycosides, and caffeine are the main taste-active compounds contributing to the taste of Tieguanyin oolong tea. The concentrations of total volatiles and most of the esters increased markedly with the semi-fermentation time, while the concentrations of low aldehydes showed a significant decrease. The flavor index was consistent with the intensity of floral aroma, increasing from 0.59 (12 h) to 0.84 (24 h) and then decreasing to 0.63 (32 h). Results of this work suggest that the flavor change is mainly due to the variation of taste-active and aroma-active compounds in oolong tea.
Journal Article
Chitosan hydrogel encapsulated with LL-37 peptide promotes deep tissue injury healing in a mouse model
Background
LL-37 peptide is a member of the human cathelicidin family, and has been shown to promote the healing of pressure ulcers. However, the low stability of this peptide within the wound environment limits its clinical use. Chitosan (CS) hydrogel is commonly used as a base material for wound dressing material.
Methods
CS hydrogel (2.5% w/v) was encapsulated with LL-37. Cytotoxicity of the product was examined in cultured NIH3T3 fibroblasts. Effects on immune response was examined by measuring tumor necrosis factor-α (TNF-α) release from RAW 264.7 macrophages upon exposure to lipopolysaccharides. Antibacterial activity was assessed using
Staphylococcus aureus
. Potential effect on pressure ulcers was examined using a mouse model. Briefly, adult male C57BL/6 mice were subjected to skin pressure using magnets under a 12/12 h schedule for 21 days. Mice were randomized to receive naked LL-37 (20 μg), chitosan gel containing 20-μg LL-37 (LL-37/CS hydrogel) or hydrogel alone under the ulcer bed (
n
= 6). A group of mice receiving no intervention was also included as a control.
Results
LL-37/CS hydrogel did not affect NIH3T3 cell viability. At a concentration of 1–5 μg/ml, LL-37/CS inhibited TNF-α release from macrophage. At 5 μg/ml, LL-37/CS inhibited the growth of
Staphylococcus aureus.
The area of the pressure ulcers was significantly lower in mice receiving LL-37/CS hydrogel in comparison to all other 3 groups on days 11 (84.24% ± 0.25%), 13 (56.22% ± 3.91%) and 15 (48.12% ± 0.28%). Histological examination on days 15 and 21 showed increased epithelial thickness and density of newly-formed capillary with naked LL-37 and more so with LL-37/CS. The expression of key macromolecules in the process of angiogenesis (i.e., hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor-A (VEGF-A)) in wound tissue was increased at both the mRNA and protein levels.
Conclusion
Chitosan hydrogel encapsulated with LL-37 is biocompatible and could promote the healing of pressure ulcers.
Journal Article
Pair combinations of human monoclonal antibodies fully protected mice against bunyavirus SFTSV lethal challenge
Severe fever with thrombocytopenia syndrome (SFTS) is a viral hemorrhagic fever caused by a tick-borne virus SFTSV with a mortality rate of up to 30%. Currently, there is no vaccine or effective therapy for SFTS. Neutralizing monoclonal antibody therapy, which provides immediate passive immunity and may limit disease progression, has emerged as a reliable approach for developing therapeutic drugs for SFTS. In this study, 4 human monoclonal antibodies (hmAbs) derived from convalescent SFTS patients’ lymphocytes based on human single-chain variable fragment antibody libraries were tested for their neutralizing activities in cells and their treatment effect in animals individually and in pair combinations. The neutralization test showed that all 4 hmAbs exhibited strong neutralizing activity against SFTSV infection in vitro . The protection rate of hmAbs 4-6, 1F6, 1B2, and 4-5 against SFTSV lethal challenge in IFNAR1 -/- A129 mice are 50%, 16.7%, 83.3%, and 66.7%, respectively. Notably, the pair combination of antibodies (1B2 and 4-5, 1B2 and 1F6) that recognized distinct epitopes protected 100% of mice against SFTSV lethal challenge. In conclusion, our findings indicate that the pair combinations of hmAbs 1B2 and 4-5 or hmAbs 1B2 and 1F6 may serve as promising therapeutic drugs for treating SFTSV infection.
Journal Article