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"Min, Yan"
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Surface ligand controls silver ion release of nanosilver and its antibacterial activity against Escherichia coli
Understanding the mechanism of nanosilver-dependent antibacterial activity against microorganisms helps optimize the design and usage of the related nanomaterials. In this study, we prepared four kinds of 10 nm-sized silver nanoparticles (AgNPs) with dictated surface chemistry by capping different ligands, including citrate, mercaptopropionic acid, mercaptohexanoic acid, and mercaptopropionic sulfonic acid. Their surface-dependent chemistry and antibacterial activities were investigated. Owing to the weak bond to surface Ag, short carbon chain, and low silver ion attraction, citrate-coated AgNPs caused the highest silver ion release and the strongest antibacterial activity against
, when compared to the other tested AgNPs. The study on the underlying antibacterial mechanisms indicated that cellular membrane uptake of Ag, NAD
/NADH ratio increase, and intracellular reactive oxygen species (ROS) generation were significantly induced in both AgNP and silver ion exposure groups. The released silver ions from AgNPs inside cells through a Trojan-horse-type mechanism were suggested to interact with respiratory chain proteins on the membrane, interrupt intracellular O
reduction, and induce ROS production. The further oxidative damages of lipid peroxidation and membrane breakdown caused the lethal effect on
. Altogether, this study demonstrated that AgNPs exerted antibacterial activity through the release of silver ions and the subsequent induction of intracellular ROS generation by interacting with the cell membrane. The findings are helpful in guiding the controllable synthesis through the regulation of surface coating for medical care purpose.
Journal Article
Pseudo-adsorption and long-range redox coupling during oxygen reduction reaction on single atom electrocatalyst
Fundamental understanding of the dynamic behaviors at the electrochemical interface is crucial for electrocatalyst design and optimization. Here, we revisit the oxygen reduction reaction mechanism on a series of transition metal (M = Fe, Co, Ni, Cu) single atom sites embedded in N-doped nanocarbon by ab initio molecular dynamics simulations with explicit solvation. We have identified the dissociative pathways and the thereby emerged solvated hydroxide species for all the proton-coupled electron transfer (PCET) steps at the electrochemical interface. Such hydroxide species can be dynamically confined in a “pseudo-adsorption” state at a few water layers away from the active site and respond to the redox event at the catalytic center in a coupled manner within timescale less than 1 ps. In the PCET steps, the proton species (in form of hydronium in neutral/acidic media or water in alkaline medium) can protonate the pseudo-adsorbed hydroxide without needing to travel to the direct catalyst surface. This, therefore, expands the reactive region beyond the direct catalyst surface, boosting the reaction kinetics via alleviating mass transfer limits. Our work implies that in catalysis the reaction species may not necessarily bind to the catalyst surface but be confined in an active region.
The reaction region is commonly considered to be the direct catalyst surface. Here, the authors challenge this view and use molecular dynamics simulations to reveal a solvated hydroxide species dynamically confined in a pseudo-adsorption state at a few water layers away from the active site during oxygen reduction reaction on single atom electrocatalyst.
Journal Article
تدويل العملات والتحكم الكلي بالمخاطر المالية
شهد الاقتصاد الصيني مؤخرا طبيعة جديدة مع الانتعاش الاقتصادي العالمي وديناميكية السوق المالي. ورغم الضغوطات الاقتصادية المحلية والعالمية وتغير قيمة العملة، لا يزال تدويل العملة في الصين يكتسب زخما كبيرا مع إطلاق المرحلة الأولى من نظام الحدود بين البنوك (CIPS) وتنفيذ مبادرة الحزام والطريق. من هنا، يعالج هذا الكتاب موضوع تدويل العملة في الصين والتحكم الكلي بالمخاطر المالية المحدقة، بهدف إلقاء الضوء على أسباب تقدم الاقتصاد الصيني، وإعطاء القارئ لمحة موجزة عن السياسة الحكيمة التي اعتمدتها حكومة جمهورية الصين الشعبية للنهوض باقتصادها والوصول به إلى مصاف الدول المتقدمة.
Emerging opportunities and challenges for the future of reservoir computing
Reservoir computing originates in the early 2000s, the core idea being to utilize dynamical systems as reservoirs (nonlinear generalizations of standard bases) to adaptively learn spatiotemporal features and hidden patterns in complex time series. Shown to have the potential of achieving higher-precision prediction in chaotic systems, those pioneering works led to a great amount of interest and follow-ups in the community of nonlinear dynamics and complex systems. To unlock the full capabilities of reservoir computing towards a fast, lightweight, and significantly more interpretable learning framework for temporal dynamical systems, substantially more research is needed. This Perspective intends to elucidate the parallel progress of mathematical theory, algorithm design and experimental realizations of reservoir computing, and identify emerging opportunities as well as existing challenges for large-scale industrial adoption of reservoir computing, together with a few ideas and viewpoints on how some of those challenges might be resolved with joint efforts by academic and industrial researchers across multiple disciplines.
Reservoir Computing has shown advantageous performance in signal processing and learning tasks due to compact design and ability for fast training. Here, the authors discuss the parallel progress of mathematical theory, algorithm design and experimental realizations of Reservoir Computers, and identify emerging opportunities as well as existing challenges for their large-scale industrial adoption.
Journal Article
A Keplerian Ag90 nest of Platonic and Archimedean polyhedra in different symmetry groups
Polyhedra are ubiquitous in chemistry, biology, mathematics and other disciplines. Coordination-driven self-assembly has created molecules mimicking Platonic, Archimedean and even Goldberg polyhedra, however, nesting multiple polyhedra in one cluster is challenging, not only for synthesis but also for determining the alignment of the polyhedra. Here, we synthesize a nested Ag
90
nanocluster under solvothermal condition. This
pseudo
-T
h
symmetric Ag
90
ball contains three concentric Ag polyhedra with apparently incompatible symmetry. Specifically, the inner (Ag
6
) and middle (Ag
24
) shells are octahedral (O
h
), an octahedron (a Platonic solid with six 3.3.3.3 vertices) and a truncated octahedron (an Archimedean solid with twenty-four 4.6.6 vertices), whereas the outer (Ag
60
) shell is icosahedral (I
h
), a rhombicosidodecahedron (an Archimedean solid with sixty 3.4.5.4 vertices). The Ag
90
nanocluster solves the apparent incompatibility with the most symmetric arrangement of 2- and 3-fold rotational axes, similar to the arrangement in the model called Kepler’s Kosmos, devised by the mathematician John Conway.
Nested polyhedra are compelling but incredibly complex synthetic targets in cluster chemistry. Here, the authors synthesize a Ag
90
nanocluster comprising three concentric polyhedra with apparently incompatible octahedral (O
h
) and icosahedral (I
h
) symmetry, a mathematical oddity that is solved by the shells’ symmetric arrangement around rotational 2- and 3-fold axes.
Journal Article
X-ray-activated long persistent phosphors featuring strong UVC afterglow emissions
Phosphors emitting visible and near-infrared persistent luminescence have been explored extensively owing to their unusual properties and commercial interest in their applications such as glow-in-the-dark paints, optical information storage, and in vivo bioimaging. However, no persistent phosphor that features emissions in the ultraviolet C range (200–280 nm) has been known to exist so far. Here, we demonstrate a strategy for creating a new generation of persistent phosphor that exhibits strong ultraviolet C emission with an initial power density over 10 milliwatts per square meter and an afterglow of more than 2 h. Experimental characterizations coupled with first-principles calculations have revealed that structural defects associated with oxygen introduction-induced anion vacancies in fluoride elpasolite can function as electron traps, which capture and store a large number of electrons triggered by X-ray irradiation. Notably, we show that the ultraviolet C afterglow intensity of the yielded phosphor is sufficiently strong for sterilization. Our discovery of this ultraviolet C afterglow opens up new avenues for research on persistent phosphors, and it offers new perspectives on their applications in terms of sterilization, disinfection, drug release, cancer treatment, anti-counterfeiting, and beyond.
Journal Article
Study on the restoration and characteristics of the entrance space of Zuoyin Garden in Huizhou
Zuoyin Garden, built by Huizhou dramatist and publisher Wang Tingne in the late Ming Dynasty, is one of the most representative private gardens in Huizhou, China, and has increasingly attracted scholars’ attention in recent years. Chinese traditional gardens have always focused on the selection, design and organization of the entrance. The entrance space of Zuoyin Garden is different from other gardens in Huizhou, which is the focus of this paper. Based on the analysis of the long scroll print of Huizhou, the Garden View of Huancui Hall and the Notes of Huancui Hall of Mr. Zuoyin, this paper attempts to restore the layout relationship and spatial appearance of the entrance area of Zuoyin Garden, and analyzes its construction characteristics from a streamline and function perspective. The result shows that in the entrance construction of the Zuoyin Garden in late Ming dynasty, some characteristics of Huizhou garden construction are reflected, and the complex and contradictory mentality of the garden owner Wang Tingne is presented. The processing of the entrance space meets the activity requirements of different groups and functions, and reflects the characteristics of excursion, publicness and openness rarely observed in private gardens. This expands the research content of the garden in Huizhou and may be used for reference in contemporary landscape design.
Journal Article
GDF15 promotes the proliferation of cervical cancer cells by phosphorylating AKT1 and Erk1/2 through the receptor ErbB2
Background
Growth differentiation factor 15 (GDF15) is a member of the TGF-β superfamily, and evidence suggests that a substantial amount of GDF15 is secreted in various human cancers, such as ovarian cancer, prostate cancer, and breast cancer, among others. However, the function of GDF15 in cervical cancer has not yet been reported.
Methods
Immunohistochemistry was used to detect GDF15 expression in normal cervix and in different cervical cancer lesions. Cell growth curves, MTT, tumor formation assays and flow cytometry were utilized to observe the effects of ectopic GDF15 expression on the proliferation and cell cycle of cervical cancer cells. Real-time PCR, western blotting and immunoprecipitation assays were conducted to measure the expression of genes related to the cell cycle and the PI3K/AKT and MAPK/ERK signaling pathways. A chromatin immunoprecipitation assay was performed to confirm whether C-myc bound to a specific region of the GDF15 promoter. Inhibitor treatment and immunoprecipitation assays were employed to identify the association between GDF15 and ErbB2.
Results
GDF15 expression gradually increased during the progression of cervical carcinogenesis. GDF15 promoted cervical cancer cell proliferation via exogenous rhGDF15 treatment or the use of gene editing technology in vitro
and
in vivo and significantly accelerated the cell cycle transition from G0/G1 to S phase. The expression of p-ErbB2, p-AKT1, p-Erk1/2, CyclinD1 and CyclinE1 was up-regulated and the expression of p21 was down-regulated in GDF15-overexpressing and rhGDF15-treated cervical cancer cells. C-myc trans-activated GDF15 expression by binding to the E-box motifs in the promoter of GDF15 and contributed to the positive feedback of GDF15/C-myc/GDF15. Furthermore, GDF15 bound to ErbB2 in a protein complex in cervical cancer cells.
Conclusions
Our data demonstrated that GDF15 promoted the proliferation of cervical cancer cells via the up-regulation of CyclinD1 and CyclinE1 and the down-regulation of p21 through both the PI3K/AKT and MAPK/ERK signaling pathways in a complex with ErbB2.
Journal Article