Nanolasers are key elements in the implementation of optical integrated circuits owing to their low lasing thresholds, high energy efficiencies, and high modulation speeds. With the development of ...semiconductor wafer growth and nanofabrication techniques, various types of wavelength‐scale and subwavelength‐scale nanolasers have been proposed. For example, photonic crystal lasers and plasmonic lasers based on the feedback mechanisms of the photonic bandgap and surface plasmon polaritons, respectively, have been successfully demonstrated. More recently, nanolasers employing new mechanisms of light confinement, including parity–time symmetry lasers, photonic topological insulator lasers, and bound states in the continuum lasers, have been developed. Here, the operational mechanisms, optical characterizations, and practical applications of these nanolasers based on recent research results are outlined. Their scientific and engineering challenges are also discussed.
Recent progress of five representative nanolasers, including photonic crystal lasers, plasmonic lasers, parity–time symmetry lasers, photonic topological insulator lasers, and bound states in the continuum lasers, is reviewed in terms of their operational principles, optical properties, and practical applications. The future perspectives and challenges of these nanolasers are also discussed.
To realize wearable displays and interactive soft robots, significant research efforts are focused on developing highly deformable alternating‐current electroluminescent (ACEL) devices. Although soft ...emission layers are well developed, designing stretchable, conductive, and transparent soft electrodes remains challenging. In this study, ionic hydrogels are prepared comprising a double network (DN) of poly(N‐hydroxyethylacrylamide‐co‐acrylamide)/crosslinked chitosan swollen in aqueous lithium bis(trifluoromethanesulfonyl) imide. Owing to the finely tuned DN structure of the polymeric crosslinker and transparent electrolyte, the developed ionic hydrogels exhibit remarkable stretchability (1400%), excellent optical transmittance (>99%), and high conductivity (1.95 × 10−2 Sm−1). Based on the high performance of the ionic hydrogels, ACEL devices are fabricated with an emission layer containing phosphor microparticles and demonstrate stable, high luminance under extreme deformation, and ultra‐high elongation. The excellent transparency of the ionic hydrogel further enables the fabrication of novel soft ACEL devices with tandem structures by stacking several emission and electrode layers, in which each emission layer is independently controlled with a switch circuit.
Highly stretchable alternating current electroluminescent devices are developed based on soft electrodes comprising ionic hydrogels with a double‐network structure. Their high optical transparency and mechanical robustness allow extreme deformability and high stretchability over 1400% as well as a multi‐stacked structure, meeting the requirements of a soft electrode for future wearable devices.
In this paper, channel estimation techniques and phase shift design for intelligent reflecting surface (IRS)-empowered single-user multiple-input multiple-output (SU-MIMO) systems are proposed. The ...two novel channel estimation techniques proposed in the paper, single-path approximated channel (SPAC) and selective emphasis on rank-one matrices (SEROM), have low training overhead to enable practical IRS-empowered SU-MIMO systems. SPAC is mainly based on parameter estimation by approximating IRS-related channels as dominant single-path channels. SEROM exploits IRS phase shifts as well as training signals for channel estimation and easily adjusts its training overhead. A closed-form solution for IRS phase shift design is also developed to maximize spectral efficiency where the solution only requires basic linear operations. Numerical results show that SPAC and SEROM combined with the proposed IRS phase shift design achieve high spectral efficiency even with low training overhead compared to existing methods.
Fluorine doping of a compositionally graded cathode, with an average concentration of LiNi
0.80
Co
0.05
Mn
0.15
O
2
, yields a high discharge capacity of 216 mA h g
−1
with unprecedented cycling ...stability by retaining 78% of its initial capacity after 8000 cycles. The cathode is cycled at 100% depth of discharge (DOD), unlike the currently deployed layered cathode whose DOD is limited to 60-80% to compensate for capacity fading and guarantee the required battery life. Additionally, the capacity and cycling stability of the cathode easily surpass those of the existing state-of-the-art batteries, while achieving the energy density goal of 800 W h kg
−1
cathode
for electric vehicles (EV) with ultra-long cycle life. The structural and chemical stabilities of the cathode were provided by the compositional partitioning and unique microstructure of the compositionally graded cathode combined with the ordered site-intermixing of Li and transition metal (TM) ions discovered
via
transmission electron microscopy. F doping induced the formation of a 2
a
hex
× 2
a
hex
×
c
hex
superlattice from ordered Li occupation in TM slabs and
vice versa
, which has been proven to be essential for suppressing microcrack formation in deeply charged states, while maintaining the structural stability of the cathode during extended cycling. Furthermore, the proposed cathode allows for the recycling of used EV batteries in energy storage systems, thereby alleviating the negative environmental impact by reducing the CO
2
emissions and cost associated with disposing of dead batteries.
The observed ultra-long battery life of 8000 cycles demonstrated by the Ni-rich compositionally graded NCM cathode stems mainly from the cation ordered structure.
This paper investigates a distributed connectivity-preserving and collision-avoiding formation tracking problem of networked uncertain underactuated surface vessels (USVs) with heterogeneous limited ...communication ranges. All nonlinearities in the dynamic model are assumed to be completely unknown. Compared with the existing formation tracking results for USVs, our primary contribution is to develop a new nonlinearly transformed formation error for achieving the initial connectivity preservation, the collision avoidance, and the distributed formation tracking without switching the desired formation pattern and using any additional potential functions. In other words, these three objectives can be achieved by using only one transformed formation error surface. The local tracker design strategy using the nonlinearly transformed error is established under the direct graph topology, where the adaptive function approximation technique and the auxiliary variables are employed to compensate for uncertain nonlinearities and to deal with the underactuated problem of USVs, respectively. Finally, the Lyapunov stability analysis and simulations are performed to verify the effectiveness of the proposed theoretic result.
Therapeutic targets are needed to develop neuroprotective treatments for Parkinson's disease (PD). Mitophagy, the selective autophagic elimination of dysfunctional mitochondria, is essential for the ...maintenance of mitochondrial integrity and is predominantly regulated by the PINK1/Parkin-mediated pathway. Loss of function mutations in Parkin and PINK1 cause an accumulation of dysfunctional mitochondria, leading to nigral neurodegeneration and early-onset PD with a high penetrance rate. We previously identified an asymptomatic homozygous Parkin mutation carrier who had not developed PD by her eighth decade despite the loss of functional Parkin. Here we discover a putative mechanism that protects her against PD. In contrast to Parkin-related PD patient-derived cells, the asymptomatic carrier cells show preserved mitochondrial function and mitophagy which is mediated by mitochondrial receptor Nip3-like protein X (Nix). Nix-mediated mitophagy was not affected by PINK1 knockdown. Both genetic and pharmacological induction of Nix restores mitophagy in PINK1- and Parkin-related PD patient cell lines, confirming its ability to induce mitophagy in the absence of PINK1/Parkin-mediated pathway. Moreover, Nix over-expression improves mitochondrial ATP production in these patient cells. Our results demonstrate that Nix can serve as an alternative mediator of mitophagy to maintain mitochondrial turnover, identifying Nix as a promising target for neuroprotective treatment in PINK1/Parkin-related PD.
Oxidative stress caused by free radicals has been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). Edaravone (also known as MCI-186), a free radical scavenger, was approved as ...an ALS treatment in 2015 in Japan. However, the therapeutic effects of edaravone on patients with ALS outside of Japan are not yet reported. This study aims to investigate effects of edaravone on ALS patients in the Korean population. The study included 22 patients with ALS who were treated with edaravone. Of the 16 patients who finished six cycles of treatment, a mean decline of ALSFRS-R after the treatments was 5.75 ± 6.07 points and the average change of FVC was − 8.7 ± 17.0%. Patients experienced only minor adverse events. This study reports on the open-label study of edaravone on patients in Korea for ALS patients, which showed a modest effect of edaravone in this population of ALS patients.
The rational design of cathode materials for lithium–selenium (Li–Se) batteries is essential to achieve high-performance electrochemical properties with long cycle life and excellent rate capability. ...In this paper, novel porous carbon nanofibers with bimodal pores (micro/meso), as efficient cathode hosts for Li–Se batteries, were successfully synthesized by carbonization of electrospun zeolitic imidazole framework-8/polyacrylonitrile (ZIF-8/PAN) nanofibers and further chemical activation. Mesopores originated from carbonization of ZIF-8 embedded in the carbon nanofiber, and micropores were further introduced via KOH activation. During the activation step, micropores were introduced to the ZIF-8-derived meso porous carbon cages and within the carbon nanofibers, resulting in the formation of bimodal porous carbon nanofibers with enlarged pore volumes. Owing to their mesopores for easy access of electrolyte and high utilization of chain-like selenium with low-range ordering within the micropore, the selenium-loaded bimodal porous carbon nanofibers exhibited high discharge capacity and superb rate performance. The discharge capacities of the nanofibers at the 2 nd and 300 th cycle at a current density of 0.5C were 742 and 588 mA h g −1 , respectively. The capacity retention calculated from the 2 nd cycle was 79.2%. In addition, a discharge capacity of 568 mA h g −1 was obtained at an extremely high current density of 10.0C.
2D nanomaterials have been found to show surface‐dominant phenomena and understanding this behavior is crucial for establishing a relationship between a material's structure and its properties. Here, ...the transition of molybdenum disulfide (MoS2) from a diffusion‐controlled intercalation to an emergent surface redox capacitive behavior is demonstrated. The ultrafast pseudocapacitive behavior of MoS2 becomes more prominent when the layered MoS2 is downscaled into nanometric sheets and hybridized with reduced graphene oxide (RGO). This extrinsic behavior of the 2D hybrid is promoted by the fast Faradaic charge‐transfer kinetics at the interface. The heterostructure of the 2D hybrid, as observed via high‐angle annular dark field–scanning transmission electron microscopy and Raman mapping, with a 1T MoS2 phase at the interface and a 2H phase in the bulk is associated with the synergizing capacitive performance. This 1T phase is stabilized by the interactions with the RGO. These results provide fundamental insights into the surface effects of 2D hetero‐nanosheets on emergent electrochemical properties.
The extrinsic surface charge‐storage behavior of 2D RGO/MoS2 hybrids translated from diffusion‐controlled intercalation mechanism is demonstrated. The 2D RGO/MoS2 hybrids exhibit a 1T phase of MoS2 at the interface interacting with the RGO sheets, where the Faradaic charge‐transfer process is facilitated by the strong interplay between the redox‐active MoS2 and electrically conductive RGO sheets.
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