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الفكر في الصين اليوم
تناول الكتاب الفكر حول الصين اليوم حيث أنه خلال القرون الثلاثة الأخيرة التي شهدت تكون الحداثة الغربية وسيطرتها، تكونت عن الصين وترسخت صورة صين صاحبة كتابة رمزية، خاضعة لموروث استبدادي، معزولة عن سائر بقاع العالم، طوال قرون، وهو ما يفسر جمودها الفلسفي والسياسي والعلمي الذي جاء الغرب في الوقت المناسب لإيقاظها منه. فحين ننظر إلى كل هذه الترهات، سوف نجدها، بالتأكيد، بصيغ مختلفة وعلى مستويات متفاوتة التنميق، في عدد لا بأس به من المؤلفات الرائجة. وعلينا أن نضيف أن هذه المؤلفات لم تعدم، في المقابل، أن تمارس تأثيرا كبيرا في طريقة النخب الصينية تنظر بها إلى ثقافتها الخاصة، سواء في انتقاد الذات أو، خلافا لذلك كما هو الحال منذ فترة وجيزة، في مدح هذه الذات مدحا معززا بشعور قومي متزايد النخوة.
Book
FBG-Based Monitoring of Geohazards: Current Status and Trends
In recent years, natural and anthropogenic geohazards have occured frequently all over the world, and field monitoring is becoming an increasingly important task to mitigate these risks. However, conventional geotechnical instrumentations for monitoring geohazards have a number of weaknesses, such as low accuracy, poor durability, and high sensitivity to environmental interferences. In this aspect, fiber Bragg grating (FBG), as a popular fiber optic sensing technology, has gained an explosive amount of attention. Based on this technology, quasi-distributed sensing systems have been established to perform real-time monitoring and early warning of landslides, debris flows, land subsidence, earth fissures and so on. In this paper, the recent research and development activities of applying FBG systems to monitor different types of geohazards, especially those triggered by human activities, are critically reviewed. The working principles of newly developed FBG sensors are briefly introduced, and their features are summarized. This is followed by a discussion of recent case studies and lessons learned, and some critical problems associated with field implementation of FBG-based monitoring systems. Finally the challenges and future trends in this research area are presented.
Journal Article
Dopamine D2 receptor regulates cortical synaptic pruning in rodents
Synaptic pruning during adolescence is important for appropriate neurodevelopment and synaptic plasticity. Aberrant synaptic pruning may underlie a variety of brain disorders such as schizophrenia, autism and anxiety. Dopamine D2 receptor (Drd2) is associated with several neuropsychiatric diseases and is the target of some antipsychotic drugs. Here we generate self-reporting Drd2 heterozygous (SR-Drd2
+/−
) rats to simultaneously visualize Drd2-positive neurons and downregulate Drd2 expression. Time course studies on the developing anterior cingulate cortex (ACC) from control and SR-Drd2
+/−
rats reveal important roles of Drd2 in regulating synaptic pruning rather than synapse formation. Drd2 also regulates LTD, a form of synaptic plasticity which includes some similar cellular/biochemical processes as synaptic pruning. We further demonstrate that Drd2 regulates synaptic pruning via cell-autonomous mechanisms involving activation of mTOR signaling. Deficits of Drd2-mediated synaptic pruning in the ACC during adolescence lead to hyper-glutamatergic function and anxiety-like behaviors in adulthood. Taken together, our results demonstrate important roles of Drd2 in cortical synaptic pruning.
Synaptic pruning is important during development and synaptic plasticity. Here, the authors show that the dopamine D2 receptor (Drd2) in the anterior cingulate cortex regulates synaptic pruning, affecting LTD and behaviour in transgenic rats.
Journal Article
Chemotherapeutic paclitaxel and cisplatin differentially induce pyroptosis in A549 lung cancer cells via caspase-3/GSDME activation
Gasdermin E (GSDME) has an important role in inducing secondary necrosis/pyroptosis. Upon apoptotic stimulation, it can be cleaved by activated caspase-3 to generate its N-terminal fragment (GSDME-NT), which executes pyroptosis by perforating the plasma membrane. GSDME is expressed in many human lung cancers including A549 cells. Paclitaxel and cisplatin are two representative chemotherapeutic agents for lung cancers, which induce apoptosis via different action mechanisms. However, it remains unclear whether they can induce GSDME-mediated secondary necrosis/pyroptosis in lung A549 cancer cells. Here we showed that both paclitaxel and cisplatin evidently induced apoptosis in A549 cells as revealed by the activation of multiple apoptotic markers. Notably, some of the dying cells displayed characteristic morphology of secondary necrosis/pyroptosis, by blowing large bubbles from the cellular membrane accompanied by caspase-3 activation and GSDME-NT generation. But the ability of cisplatin to induce this phenomenon was much stronger than that of paclitaxel. Consistent with this, cisplatin triggered much higher activation of caspase-3 and generation of GSDME-NT than paclitaxel, suggesting that the levels of secondary necrosis/pyroptosis correlated with the levels of active caspase-3 and GSDME-NT. Supporting this, caspase-3 specific inhibitor (Ac-DEVD-CHO) suppressed cisplatin-induced GSDME-NT generation and concurrently reduced the secondary necrosis/pyroptosis. Besides, GSDME knockdown significantly inhibited cisplatin- but not paclitaxel-induced secondary necrosis/pyroptosis. These results indicated that cisplatin induced higher levels of secondary necrosis/pyroptosis in A549 cells than paclitaxel, suggesting that cisplatin may provide additional advantages in the treatment of lung cancers with high levels of GSDME expression.
Journal Article
Effect of ultrasonic surface deep rolling combined with oxygen boost diffusion treatment on fatigue properties of pure titanium
Ultrasonic surface deep rolling (USDR), oxygen boost diffusion (OBD), and their combination (USDR-OBD) were all used to improve the surface hardening of pure titanium. The microstructure, microhardness, and fatigue life of pure titanium treated by USDR, OBD, and USDR-OBD methods were analyzed. USDR treatment induced a severe deformation area, while OBD treatment produced a brittle oxygen diffusion zone. The USDR-OBD treated samples approached the highest hardness in comparison with other treated samples. The fatigue lives of USDR treated samples were improved, which was due to the high compressive residual stress and refined grains. However, the fatigue lives of both OBD treated samples and USDR-OBD treated samples were decreased due to premature crack initiation and rapid propagation in the oxygen diffusion zone. Finally, the fatigue fracture mechanisms of different samples were proposed.
Journal Article
Greybody factor and power spectra of the Hawking radiation in the 4D Einstein–Gauss–Bonnet de-Sitter gravity
A novel 4D Einstein–Gauss–Bonnet gravity was recently formulated by Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)]. Although this theory may run into trouble at the level of action or equations of motion, the spherically symmetric black hole solution, which can be successfully reproduced in those consistent theories of 4D EGB gravity, is still meaningful and worthy of study. In this paper, we investigate Hawking radiation in the spacetime containing such a de Sitter black hole. Both the greybody factor and the power spectra of the Hawking radiation of the massless scalar are studied numerically for the full range of various parameters, including the GB coupling constant
α
, the cosmological constant
Λ
and the coupling constant related to the scalar filed
ξ
. In particular, we find a negative
α
leads to a larger greybody factor than that of a
α
≥
0
. While, for the power spectra of the Hawking radiation the situation is quite the opposite. The reason is that the temperature of the black hole would be very high when
α
<
0
. Actually, we observe that the temperature would be arbitrarily high when
α
approaches to the lower bound.
Journal Article
Quantized Anomalous Hall Effect in Magnetic Topological Insulators
The anomalous Hall effect is a fundamental transport process in solids arising from the spin-orbit coupling. In a quantum anomalous Hall insulator, spontaneous magnetic moments and spin-orbit coupling combine to give rise to a topologically nontrivial electronic structure, leading to the quantized Hall effect without an external magnetic field. Based on first-principles calculations, we predict that the tetradymite semiconductors Bi₂Te₃, Bi₂Se₃, and Sb₂Te₃ form magnetically ordered insulators when doped with transition metal elements (Cr or Fe), in contrast to conventional dilute magnetic semiconductors where free carriers are necessary to mediate the magnetic coupling. In two-dimensional thin films, this magnetic order gives rise to a topological electronic structure characterized by a finite Chern number, with the Hall conductance quantized in units of e²/h (where e is the charge of an electron and h is Planck's constant).
Journal Article
Oxidative stress in cyanobacteria
Reactive oxygen species (ROS) are byproducts of aerobic metabolism and potent agents that cause oxidative damage. In oxygenic photosynthetic organisms such as cyanobacteria, ROS are inevitably generated by photosynthetic electron transport, especially when the intensity of light-driven electron transport outpaces the rate of electron consumption during CO₂ fixation. Because cyanobacteria in their natural habitat are often exposed to changing external conditions, such as drastic fluctuations of light intensities, their ability to perceive ROS and to rapidly initiate antioxidant defences is crucial for their survival. This review summarizes recent findings and outlines important perspectives in this field.
Journal Article
Synthesis of propenone-linked covalent organic frameworks via Claisen-Schmidt reaction for photocatalytic removal of uranium
The type of reactions and the availability of monomers for the synthesis of
sp
2
-c
linked covalent organic frameworks (COFs) are considerably limited by the irreversibility of the C=C bond. Herein, inspired by the Claisen-Schmidt condensation reaction, two propenone-linked (C=C–C=O) COFs (named Py-DAB and PyN-DAB) are developed based on the base-catalyzed nucleophilic addition reaction of ketone-activated
α
-H with aromatic aldehydes. The introduction of propenone structure endows COFs with high crystallinity, excellent physicochemical stability, and intriguing optoelectronic properties. Benefitting from the rational design on the COFs skeleton, Py-DAB and PyN-DAB are applied to the extraction of radionuclide uranium. In particular, PyN-DAB shows excellent removal rates (>98%) in four uranium mine wastewater samples. We highlight that such a general strategy can provide a valuable avenue toward various functional porous crystalline materials.
The synthesis of
sp
2
carbon-conjugated covalent organic frameworks is limited to a few reactions and monomers due to the poor irreversibility of carbon double bonds. Here the authors synthesize propenone-linked covalent organic frameworks for the removal of radionuclide uranium from mine wastewater samples.
Journal Article