Abstract
In response to the changing geopolitical landscape in Asia, both China and the United States attempt to alter the regional order in their own favour, both in the economic and security ...realms. This article shows how diverging views on future arrangements are leading to strategic shifts and increasing tension between these two Great Powers. As part of its quest for Great-Power status, China has been actively pushing its regional initiatives such as the Belt and Road Initiative (BRI) and the Asian Infrastructure Investment Bank (AIIB), as well as adopting assertive security policies towards its neighbours. In contrast, in order to counter China's growing influence America's regional strategy is undergoing a subtle shift from ‘rebalancing to Asia’ to focusing on the ‘Indo-Pacific’ region. However, amid an intensifying trade war and other challenges facing the region, China has chosen to moderate its proactive foreign policy-orientation in the past few years. In particular, China has made attempts to downplay its domestic rhetoric, rebuild strategic relationship with India and Japan, and to reassure ASEAN states in the South China Sea. In response to the Indo-Pacific strategy, it would be more effective for China to articulate a more inclusive regional vision and promote an institutional framework that also accommodates a US presence in the region.
Synergistic phototherapy has the potential to conquer the extreme heterogeneity and complexity of difficult tumors and result in better cancer treatment outcomes than monomodal photodynamic therapy ...(PDT) or photothermal therapy (PTT). However, the previous approaches to combining PDT and PTT are mainly focused on primary tumor obliteration while neglecting tumor metastasis, which is responsible for about 90% of cancer deaths. It is shown that a combined PDT/PTT approach, based on upconversion‐polymer hybrid nanoparticles with surface‐loaded chlorin e6 photosensitizer, can enhance primary tumor elimination and elicit antitumor immunity against disseminated tumors. The specifical arrangement of an external upconversion coating over the polymer core ensures adequate photoabsorption by the upconversion nanoparticles for the generation of reactive oxygen species upon single near‐infrared light irradiation. Furthermore, it is found that synergistic phototherapy can elicit robust systemic and humoral antitumor immune responses. When combined with immune checkpoint blockades, it can inhibit tumor relapse and metastasis as well as prolong the survival of tumor‐bearing mice in two types of tumor metastasis models. This study may establish a new modality for enhancing immunogenic cell death through a synergistic phototherapeutic nanoplatform and extend this strategy to overcome tumor metastasis with an augmented antitumor immune response.
Synergistic phototherapy holds potential for improved cancer treatment. Bionanoprobes are designed for synchronous phototherapy of a tumor with high efficiency and augmentation of a robust systemic antitumor immune response.
The discovery of NHCs (NHC = N‐heterocyclic carbenes) as ancillary ligands in transition‐metal‐catalysis ranks as one of the most important developments in synthesis and catalysis. It is now ...well‐recognized that the strong σ‐donating properties of NHCs along with the ease of scaffold modification and a steric shielding of the N‐wingtip substituents around the metal center enable dramatic improvements in catalytic processes, including the discovery of reactions that are not possible using other ancillary ligands. In this context, although the classical NHCs based on imidazolylidene and imidazolinylidene ring systems are now well‐established, recently tremendous progress has been made in the development and catalytic applications of BIAN‐NHC (BIAN = bis(imino)acenaphthene) class of ligands. The enhanced reactivity of BIAN‐NHCs is a direct result of the combination of electronic and steric properties that collectively allow for a major expansion of the scope of catalytic processes that can be accomplished using NHCs. BIAN‐NHC ligands take advantage of (1) the stronger σ‐donation, (2) lower lying LUMO orbitals, (3) the presence of an extended π‐system, (4) the rigid backbone that pushes the N‐wingtip substituents closer to the metal center by buttressing effect, thus resulting in a significantly improved control of the catalytic center and enhanced air‐stability of BIAN‐NHC‐metal complexes at low oxidation state. Acenaphthoquinone as a precursor enables facile scaffold modification, including for the first time the high yielding synthesis of unsymmetrical NHCs with unique catalytic properties. Overall, this results in a highly attractive, easily accessible class of ligands that bring major advances and emerge as a leading practical alternative to classical NHCs in various aspects of catalysis, cross‐coupling and C−H activation endeavors.
A comprehensive overview of BIAN‐NHC (BIAN = bis(imino)acenaphthene), NHC = N‐heterocyclic carbene) ligands in transition‐metal‐catalysis with a focus on both the catalyst structure and the scaffold's role in catalysis is presented.
Despite the rapid progress in the field of the quantum spin Hall (QSH) effect, most of the QSH systems studied up to now are based on crystalline materials. Here we propose that the QSH effect can be ...realized in quasicrystal lattices (QLs). We show that the electronic topology of aperiodic and amorphous insulators can be characterized by a spin Bott index B_{s}. The nontrivial QSH state in a QL is identified by a nonzero spin Bott index B_{s}=1, associated with robust edge states and quantized conductance. We also map out a topological phase diagram in which the QSH state lies in between a normal insulator and a weak metal phase due to the unique wave functions of QLs. Our findings not only provide a better understanding of electronic properties of quasicrystals but also extend the search of the QSH phase to aperiodic and amorphous materials that are experimentally feasible.
To overcome devices' limitations in performing computation-intense applications, mobile edge computing (MEC) enables users to offload tasks to proximal MEC servers for faster task computation. ...However, the current MEC system design is based on average-based metrics, which fails to account for the ultra-reliable low-latency requirements in mission-critical applications. To tackle this, this paper proposes a new system design, where probabilistic and statistical constraints are imposed on task queue lengths, by applying extreme value theory . The aim is to minimize users' power consumption while trading off the allocated resources for local computation and task offloading. Due to wireless channel dynamics, users are reassociated to MEC servers in order to offload tasks using higher rates or accessing proximal servers. In this regard, a user-server association policy is proposed, taking into account the channel quality as well as the servers' computation capabilities and workloads. By marrying tools from Lyapunov optimization and matching theory, a two-timescale mechanism is proposed, where a user-server association is solved in the long timescale, while a dynamic task offloading and resource allocation policy are executed in the short timescale. The simulation results corroborate the effectiveness of the proposed approach by guaranteeing highly reliable task computation and lower delay performance, compared to several baselines.
Cancer can invade or spread to almost all parts of the body. The increasing morbidity and high mortality of cancer create a great demand for the development of novel anticancer drugs. Coumarin ...derivatives are ubiquitous in nature and can readily interact with diverse enzymes and receptors in cancer cells via weak bond interactions; hence, coumarin is a highly privileged pharmacophore for the development of novel anticancer agents. This review will focus on the recent development of coumarin hybrids as potential anticancer agents covering articles published from 2019 to 2020.
Coumarin derivatives are ubiquitous in nature and can readily interact with diverse enzymes and receptors in cancer cells via weak bond interactions. This review focuses on the recent development of coumarin derivatives as potential anticancer agents and their mechanisms of action.
Untethered small actuators have various applications in multiple fields. However, existing small-scale actuators are very limited in their intractability with their surroundings, respond to only a ...single type of stimulus and are unable to achieve programmable structural changes under different stimuli. Here, we present a multiresponsive patternable actuator that can respond to humidity, temperature and light, via programmable structural changes. This capability is uniquely achieved by a fast and facile method that was used to fabricate a smart actuator with precise patterning on a graphene oxide film by hydrogel microstamping. The programmable actuator can mimic the claw of a hawk to grab a block, crawl like an inchworm, and twine around and grab the rachis of a flower based on their geometry. Similar to the large- and small-scale robots that are used to study locomotion mechanics, these small-scale actuators can be employed to study movement and biological and living organisms.
In this paper, we propose multi-input multi-output (MIMO) beamforming designs towards joint radar sensing and multi-user communications. We employ the Cramér-Rao bound (CRB) as a performance metric ...of target estimation, under both point and extended target scenarios. We then propose minimizing the CRB of radar sensing while guaranteeing a pre-defined level of signal-to-interference-plus-noise ratio (SINR) for each communication user. For the single-user scenario, we derive a closed form for the optimal solution for both cases of point and extended targets. For the multi-user scenario, we show that both problems can be relaxed into semidefinite programming by using the semidefinite relaxation approach, and prove that the global optimum can be generally obtained. Finally, we demonstrate numerically that the globally optimal solutions are reachable via the proposed methods, which provide significant gains in target estimation performance over state-of-the-art benchmarks.
Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties with many promising application prospects, such as photoelectric detectors, nonlinear optics, ...infrared photoelectric devices, and ultrafast photonics. Among them, ultrafast photonics has attracted much attention due to its enormous advantages; for instance, extremely fast pulse, strong peak power, and narrow bandwidth. In this work, SnSe2 nanosheets are fabricated by using solvothermal treatment, and the characteristics of SnSe2 are systemically investigated. In addition, the solution of SnSe2 nanosheets is successfully prepared as a fiber‐based saturable absorber by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode locking is generated in an Er‐doped fiber laser, corresponding to the maximum repetition rate of 257.3 MHz and pulse duration of 887 fs. The results show that SnSe2 can be used as an excellent nonlinear photonic device in many fields, such as frequency comb, lasers, photodetectors, etc.
Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties. SnSe2 nanosheets fabricated by using solvothermal treatment are successfully prepared as fiber‐based saturable absorbers by utilizing the evanescent field effect, which can bear a high pump power. 31st‐order subpicosecond harmonic mode‐locking is generated, corresponding to 257.3 MHz repetition rate.
The ever‐growing global threats to human life caused by the human acute respiratory virus (RV) infections have cost billions of lives, created a significant economic burden, and shaped society for ...centuries. The timely response to emerging RVs could save human lives and reduce the medical care burden. The development of RV detection technologies is essential for potentially preventing RV pandemic and epidemics. However, commonly used detection technologies lack sensitivity, specificity, and speed, thus often failing to provide the rapid turnaround times. To address this problem, new technologies are devised to address the performance inadequacies of the traditional methods. These emerging technologies offer improvements in convenience, speed, flexibility, and portability of point‐of‐care test (POCT). Herein, recent developments in POCT are comprehensively reviewed for eight typical acute respiratory viruses. This review discusses the challenges and opportunities of various recognition and detection strategies and discusses these according to their detection principles, including nucleic acid amplification, optical POCT, electrochemistry, lateral flow assays, microfluidics, enzyme‐linked immunosorbent assays, and microarrays. The importance of limits of detection, throughput, portability, and specificity when testing clinical samples in resource‐limited settings is emphasized. Finally, the evaluation of commercial POCT kits for both essential RV diagnosis and clinical‐oriented practices is included.
The advanced rapid point‐of‐care tests (POCTs), including nucleic acid amplification, optical POCTs, electrochemistry, lateral flow assay, microfluidics, ELISA, and microarray‐based platforms, act figuratively as the Great Wall to the widespread transmission of acute respiratory virus infections by enabling early and rapid detection of these pathogens, as is the case during the current pandemic.
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