Search

Donor‐acceptor Stenhouse adducts (DASAs) as a species of novel photochromic molecules, have been developing rapidly and attracting broad researchers' sights since 2014. DASAs show visible/near‐infrared (NIR) light induced linear‐to‐cyclic isomerization and heat induced cyclic‐to‐linear isomerization, therefore they are attractive in photoresponsive hydrogels, drug delivery, cell culturing and tissue engineering. As a series of well‐known photoresponsive molecules, spiropyrans (SPs) show similar molecular properties and comparable photoswitching with DASAs. UV light triggers closed‐to‐open (also known as spirocyclic (SC)‐to‐merocyanine (MC)) isomerization of SPs, while the reversed open‐to‐closed isomerization occurs under visible light or heat. Light irradiation switches the molecular color, scale, geometry, and polarity of SPs and DASAs reversibly. Since the researches on DASAs are still in the infancy, the chemical structures, isomerization mechanisms and potential applications need to be further investigated and explored. The well‐studied SPs have important reference values to the comprehensive developments of DASAs. In the present review, we summarized, compared and discussed SPs and DASAs with regards to their molecular structures, synthesis, photoswitching and applications. We also make our perspective on the developments of DASA in future. [ABSTRACT FROM AUTHOR]

A robust technique based on maximum correntropy criterion (MCC) is proposed for frequency estimation in an unbalanced power system using error in phase angle. This is achieved by replacing the magnitude error used in the standard cost function of the MCC with the phase error and by extending the concept of the augmented (widely linear) complex statistics for the processing of unbalanced voltages and other abnormal system conditions. The idea emanates from the facts that: (i) useful information is primarily conveyed over the phase in power system frequency estimation, and (ii) the performance degradation of the well‐known minimum mean squared error criterion based adaptive filters in impulsive noise environments can be overcome by the MCC due to the non‐quadratic and higher order moments imbedded in its cost function. The proposed phase error‐based MCC method also utilises all the second‐order information within the complex valued system voltage through the Clarke's transformation. Simulation studies conducted using both synthetic and experimental data verify that the proposed algorithm provides better estimations compared to the considered algorithms. [ABSTRACT FROM AUTHOR]

To improve the performance of the recently presented individual weighting factors sign subband adaptive filter (IWF-SSAF) algorithm, its 2 combination algorithms using different step sizes are proposed. The first algorithm is to convexly combine the weight vectors of a large step-size IWF-SSAF filter and a small step-size one; and the second algorithm is to obtain a time-varying step size for the IWF-SSAF by combining a large step size and a small one. The minimization of the sum of the l1-norm of subband errors is used to indirectly update the mixing parameters in these 2 algorithms through a modified sigmoidal function. Moreover, in the first algorithm, to implement a smooth transition from the large step-size IWF-SSAF filter to the small step-size one, the component filters receive a cyclic feedback of the combined weight vector. Both proposed algorithms have almost the same convergence performance, but the second algorithm saves computational cost. Simulation results in impulsive noise scenarios demonstrate the superiority of our proposed algorithms. [ABSTRACT FROM AUTHOR]

Motivated by the need for robust frequency estimation for both balanced and unbalanced power system conditions and the fact that most of the existing techniques perform poorly in the presence of external interferences, a more noise‐resilient widely linear least mean kurtosis (WL‐LMK) algorithm is proposed that uses both the magnitude and phase angle errors for online estimation of three‐phase power system frequency. The proposed method makes use of the full second‐order information within the complex‐valued system voltage through Clarke's αβ transformation and the concept of augmented complex statistics and WL modelling. The effectiveness of the proposed scheme is verified through simulation studies of synthetic signals and experimental data. [ABSTRACT FROM AUTHOR]

An incremental least‐mean M‐estimate algorithm is proposed for distributed network, which minimises a robust M‐estimator‐based cost function against impulsive noise via the gradient descent method. Moreover, based on the same frame for implementation, an incremental distributed least‐mean p‐power algorithm is presented for combating impulsive noise. Simulations verify the superiority of the proposed algorithms in the presence of impulsive noise relative to some existing incremental distributed algorithms. [ABSTRACT FROM AUTHOR]

A new class of bias‐compensated affine‐projection‐like (APL) algorithms is proposed, in which a bias‐compensation vector is derived to eliminate the bias caused by the noisy input. In addition, a new estimation method for the input noise variance is proposed which does not require the input–output noise variance ratio in advance. Simulations in a system identification context show that the proposed algorithms achieve significant improvements in steady‐state misalignment as compared with the conventional APL algorithms. [ABSTRACT FROM AUTHOR]

Proposed is an L0 norm constraint set‐membership affine projection algorithm with coefficient vector reuse, which is derived by minimising a differentiable cost function that utilises the L0 norm of the updated weight vector as well as the sum of the squared Euclidean norms of the differences between the updated weight vector and past weight vectors. In addition, a power estimate method is introduced to eliminate the effect of the fluctuation of the output error on the step size. Simulations on sparse system identifications demonstrate that the proposed algorithm achieves a lower steady‐state misalignment than the existing algorithms in a high background noise environment. [ABSTRACT FROM AUTHOR]

A variable step‐size distributed incremental normalised least mean square (DINLMS) algorithm is proposed, in which the time‐varying step‐size of each node in the distributed network is obtained by minimising a posterior estimation error at that node. It overcomes the drawback that fast convergence rate with high steady‐state misalignment or low steady‐state misalignment with slow convergence rate, which always exists in the traditional DINLMS. The simulation results show that the proposed algorithm could achieve a better performance. [ABSTRACT FROM AUTHOR]

Telocytes (TCs) are distinctive interstitial cells due to their characteristic structures and heterogeneity. They are suggested to participate in tissue repair/regeneration. TCs have been identified in many organs of various mammals. However, data on TCs in lower animals are still very limited. In this work, TCs were identified in the myocardium of the bullfrog (Rana catesbeiana) by light and transmission electron microscopy (TEM). The structural relationships between TCs and neighbouring cell types were measured using the ImageJ (FiJi) morphometric software. TCs with slender Tps (telepodes) were located around cardiomyocytes (CMC). TEM revealed TCs with long Tps in the stroma between CMC. The homocellular tight junctions were observed between the Tps. The Tps were also very close to the neighbouring CMC. The distance between Tps and CMC was 0.15 ± 0.08 μm. Notably, Tps were observed to adhere to the periphery of the satellite cells. The Tps and the satellite cells established heterocellular structural connections by tight junctions. Additionally, Tps were frequently observed in close proximity to mast cells (MCs). The distance between the Tps and the MCs was 0.19 ± 0.09 μm. These results confirmed that TCs are present in the myocardium of the bullfrog, and that TCs established structural relationships with neighbouring cell types, including satellite cells and MCs. These findings provide the anatomical evidence to support the note that TCs are involved in tissue regeneration. [ABSTRACT FROM AUTHOR]

For echo cancellation, a memory improved proportionate M‐estimate affine projection algorithm (MIP‐MAPA) is proposed in which the M‐estimator‐based cost function containing the weighting matrix is minimised as the cost function and an efficient recursive implementation is applied according to the memory of the previous step‐size control matrices. A test on echo cancellations under an impulsive noise environment showed that the proposed MIP‐MAPA achieves improvement in steady‐state misalignment compared with existing algorithms. [ABSTRACT FROM AUTHOR]

Nanoscale air channel transistors (NACTs) have received significant attention due to their remarkable high‐frequency performance and high switching speed, which is enabled by the ballistic transport of electrons in sub‐100 nm air channels. Despite these advantages, NACTs are still limited by low currents and instability compared to solid‐state devices. GaN, with its low electron affinity, strong thermal and chemical stability, and high breakdown electric field, presents an appealing candidate as a field emission material. Here, a vertical GaN nanoscale air channel diode (NACD) with a 50 nm air channel is reported, fabricated by low‐cost IC‐compatible manufacturing technologies on a 2‐inch sapphire wafer. The device boasts a record field emission current of 11 mA at 10 V in the air and exhibits outstanding stability during cyclic, long‐term, and pulsed voltage testing. Additionally, it displays fast switching characteristics and good repeatability with a response time of fewer than 10 ns. Moreover, the temperature‐dependent performance of the device can guide the design of GaN NACTs for applications in extreme conditions. The research holds great promise for large current NACTs and will speed up their practical implementation. [ABSTRACT FROM AUTHOR]

B GaN Nanoscale Air Channel Diodes b In article number 2206385 by Mo Li and co-workers, a vertical GaN nanodiode with a 50 nm air channel is reported, fabricated using IC-compatible technologies, with a record field emission current of 11 mA@10 V. Notably, the device displays outstanding stability and fast switching characteristics with a sub-10 ns response time. Additionally, the temperature-dependent performance can guide the design of nano-air-channel-devices for applications in extreme conditions. Fast Response GaN Nanoscale Air Channel Diodes with Highly Stable 10 mA Output Current toward Wafer-Scale Fabrication (Adv. Sci. 17/2023). [Extracted from the article]

In the present research, novel tri‐block‐copolymers bearing polyethylene glycol (PEG), azobenzene (Azo), and tetra‐ortho‐methoxy‐substituted Azo (mAzo) segments are synthesized and explored. Light‐controlled PEG‐PmAzo‐PAzo self‐assemblies switching between multi‐stationary states is realized. Under controlling of UV, blue, green, and red light, PEG‐PmAzo‐PAzo isomerize between 4 photostationary states. The enrichment of cis isomers of Azo and mAzo induces the self‐assembly of PEG‐PmAzo‐PAzo in toluene. The morphologies and scale of the self‐assemblies can be switched between four stationary states, which are investigated by dynamic light scattering, scanning electron microscopy, and transmission electron microscopy. [ABSTRACT FROM AUTHOR]