A Cluster-Driven Adaptive Training Approach for Federated Learning.

Federated learning (FL) is a promising collaborative learning approach in edge computing, reducing communication costs and addressing the data privacy concerns of traditional cloud-based training. Owing to this, diverse studies have been conducted to distribute FL into industry. However, there still remain the practical issues of FL to be solved (e.g., handling non-IID data and stragglers) for an actual implementation of FL. To address these issues, in this paper, we propose a cluster-driven adaptive training approach (CATA-Fed) to enhance the performance of FL training in a practical environment. CATA-Fed employs adaptive training during the local model updates to enhance the efficiency of training, reducing the waste of time and resources due to the presence of the stragglers and also provides a straggler mitigating scheme, which can reduce the workload of straggling clients. In addition to this, CATA-Fed clusters the clients considering the data size and selects the training participants within a cluster to reduce the magnitude differences of local gradients collected in the global model update under a statistical heterogeneous condition (e.g., non-IID data). During this client selection process, a proportional fair scheduling is employed for securing the data diversity as well as balancing the load of clients. We conduct extensive experiments using three benchmark datasets (MNIST, Fashion-MNIST, and CIFAR-10), and the results show that CATA-Fed outperforms the previous FL schemes (FedAVG, FedProx, and TiFL) with regard to the training speed and test accuracy under the diverse FL conditions.

Supramolecular coordination polymer formed from artificial light-harvesting dendrimer.

We report the formation of supramolecular coordination polymers formed from multiporphyrin dendrimers (PZnPM; M = FB or Cu), composed of the focal freebase porphyrin (PFB) or cupper porphyrin (PCu) with eight zinc porphyrin (PZn) wings, and multipyridyl porphyrins (PyPM; M = FB or Cu), PFB or PCu with eight pyridyl groups, through multiple axial coordination interactions of pyridyl groups to PZns. UV-vis absorption spectra were recorded upon titration of PyPFB to PZnPFB. Differential spectra, obtained by subtracting the absorption of PZnPFB without guest addition as well as the absorption of PyPFB, exhibited clear isosbestic points with saturation binding at 1 equiv addition of PyPFB to PZnPFB. Job's plot analysis also indicated 1:1 stoichiometry for the saturation binding. The apparent association constant between PZnPFB and PyPFB (2.91 × 10(6) M(-1)), estimated by isothermal titration calorimetry, was high enough for fibrous assemblies to form at micromolar concentrations. The formation of a fibrous assembly from PZnPFB and PyPFB was visualized by atomic force microscopy and transmission electron microscopy (TEM). When a 1:1 mixture solution of PZnPFB and PyPFB (20 µM) in toluene was cast onto mica, fibrous assemblies with regular height (ca. 2 nm) were observed. TEM images obtained from 1:1 mixture solution of PZnPFB and PyPFB (0.1 wt %) in toluene clearly showed the formation of nanofibers with a regular diameter of ca. 6 nm. Fluorescence emission measurement of PZnPM indicated efficient intramolecular energy transfer from PZn to the focal PFB or PCu. By the formation of supramolecular coordination polymers, the intramolecular energy transfer changed to intermolecular energy transfer from PZnPM to PyPM. When the nonfluorescent PyPCu was titrated to fluorescent PZnPFB, fluorescence emission from the focal PFB was gradually decreased. By the titration of fluorescent PyPFB to nonfluorescent PZnPCu, fluorescence emission from PFB in PyPFB was gradually increased due to the efficient energy transfer from PZn wings in PZnPCu to PyPFB.

A porphyrin-based molecular tweezer: guest-induced switching of forward and backward photoinduced energy transfer.

A bisindole-bridged-porphyrin tweezer (1), a pair of zinc porphyrins (PZn's) connected to bisindole bridge (BB) via the Cu(I)-mediated alkyne-azide click chemistry, exhibited unique switching in forward and backward photoinduced energy transfer by specific guest bindings. The addition of Cu(2+) caused a change in electronic absorption and fluorescence quenching of 1. MALDI-TOF-MS and FT-IR analyses indicated the formation of stable coordination complex between 1 and Cu(2+) (1-Cu(II)). Without Cu(2+) coordination, the excitation energy flows from BB to PZn's with significantly high energy transfer efficiency. In contrast, the direction of energy flow in 1 was completely reversed by the coordination of Cu(2+). The difference in fluorescence quantum yield between 1 and 1-Cu(II) indicates that more than 95% of excitation energy of PZn flows into Cu(II)-coordinated BB. The energy transfer efficiency was further controlled by bidentate ligand coordination onto 1-Cu(II). When pyrophosphate ion was added to 1-Cu(II), the recovery of fluorescence emission from PZn was observed. The quantum mechanical calculations indicated that the Cu(II)-coordinated BB has square planar geometry, which can be distorted to form octahedral geometry due to the coordination of bidentate ligands.

Guest-induced photophysical property switching of artificial light-harvesting dendrimers.

An artificial light-harvesting multiporphyrin dendrimer (8P(Zn)P(FB)) composed of a focal freebase porphyrin (P(FB)) with eight zinc(II) porphyrin (P(Zn)) wings exhibited unique photophysical property switching in response to specific guest molecule binding. UV/Vis titration studies indicated stable 1:2 host-guest complex formation between 8P(Zn)P(FB) and meso-tetrakis(4-pyridyl)-porphyrin (TPyP) for which the first and second association constants were estimated to be >10(8) M(-1) and 3.0×10(7) M(-1), respectively. 8P(Zn)P(FB) originally shows 94% energy transfer efficiency from P(Zn) to the focal P(FB). By the formation of the host-guest complex (8P(Zn)P(FB)⋅2TPyP) the emission intensity of 8P(Zn)P(FB) is significantly decreased, and an ultrafast charge separation state is generated. The energy transfer process from P(Zn) wings to the P(FB) core in 8P(Zn)P(FB) is almost entirely switched to an electron transfer process by the formation of 8P(Zn)P(FB)⋅2TPyP.

Nanocellulose/two dimensional nanomaterials composites for advanced supercapacitor electrodes.

With the emerging of the problems of environmental pollution and energy crisis, the development of high-efficiency energy storage technology and green renewable energy is imminent. Supercapacitors have drawn great attention in wearable electronics because of their good performance and portability. Electrodes are the key to fabricate high-performance supercapacitors with good electrochemical properties and flexibility. As a biomass based derived material, nanocellulose has potential application prospects in supercapacitor electrode materials due to its biodegradability, high mechanical strength, strong chemical reactivity, and good mechanical flexibility. In this review, the research progress of nanocellulose/two dimensional nanomaterials composites is summarized for supercapacitors in recent years. First, nanocellulose/MXene composites for supercapacitors are reviewed. Then, nanocellulose/graphene composites for supercapacitors are comprehensively elaborated. Finally, we also introduce the current challenges and development potential of nanocellulose/two dimensional nanomaterials composites in supercapacitors.

Application of Ethanol Extracts From Alnus sibirica Fisch. ex Turcz in Hair Growth Promotion.

Alnus sibirica Fisch. ex Turcz (ASFT), belonging to the family of Betulaceae, grows naturally in Asia, Europe, and America. The aims of this study are determining the efficacy of various biomarkers related to hair loss, evaluated by extracting the branch with 60% alcohol, and purely separating diarylheptanoid oregonin, an indicator and active substance, from 60% alcohol extract of the tree. To determine the preventive effects on hair loss, we investigated the anti-oxidative and anti-apoptotic effects on hydrogen peroxide-induced cytotoxicity on human hair dermal papilla cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Western blotting analysis for proving of apoptosis-related marker alteration, respectively. Moreover, we examined the ameliorative effects of 60% alcohol extract of the tree and oregonin against changes of oxidative stress-induced cytokine and testosterone-induced dihydrotestosterone production as crucial pathways of the hair loss mechanism. These results suggest that 60% alcohol extract of the tree and oregonin were available as novel natural materials for maintaining hair health in mammals.

Channel structures from self-assembled hexameric macrocycles in laterally grafted bent rod molecules.

Internally grafted bent rod molecules consisting of a bent-shaped nona-p-phenylene and different lengths of oligoether chains at the bay position were synthesized and characterized. All of the bent-shaped molecules showed ordered bulk-state structures as characterized by differential scanning calorimetry, X-ray scatterings, and transmission electron microscopy. The bent rod based on a short oligo(propylene oxide) chain self-assembles into a 2-D channel-like columnar structure, whereas the molecules with an intermediate length of flexible chains self-assemble into discrete channels that self-organize into honeycomb layers. A further increase in the length of the flexible chain induces a layered structure. In contrast to the bent-shaped molecules based on a linear chain, the molecules based on a branched chain self-assemble into an inverted 2-D columnar structure with an aromatic core surrounded by branched chains. We proposed the model of the channel structure on the basis of experimental data obtained from X-ray results and density measurements. Within the channels, six bent rods self-assemble into hexameric macrocycles that stack on one another to form channel-like columns where the interiors are filled by the flexible oligoether chains. Remarkably, the elongated channels break up into discrete channels of a well-defined length with increasing length of the oligoether chain. The resulting discrete channels self-organize into a hexagonally ordered honeycomb layer. The defined length of a channel is believed to be responsible for the formation of unique honeycomb layers.

Cascade sensing of gold and thiols with imidazole-bearing functional porphyrins.

An imidazole-bearing zinc porphyrin (PZn) has been designed for the selective detection of Au(3+), and the porphyrin and gold complex (PZn·Au(3+)) can additionally be used to identify gold-binding functional groups such as cysteine residues and other mercaptans.

A diketopyrrolopyrrole-based colorimetric and fluorescent probe for cyanide detection.

Red means CN: A new type of diketopyrrolopyrrole-based chromophore has been synthesized as a colorimetric and fluorescent probe for the detection of cyanide using only two reaction steps. Through the addition of cyanide to the chromophore, the fluorescence emission and color were greatly changed in a highly sensitive and selective manner.

A zinc porphyrin-based molecular probe for the determination of contamination in commercial acetonitrile.

A zinc porphyrin-based receptor containing four triazole groups at the ortho-position of each phenyl group (1) was utilized as a useful probe for the determination of contaminants in acetonitrile (MeCN). Through the simple observation of the absorption spectrum of 1 in MeCN, the cyanide contamination concentration could be directly determined.

Highly sensitive and selective cyanide detection via Cu2+ complex ligand exchange.

A new type of fluorescent probe (1) with two triazole groups that are conjugated with a carbazole moiety was synthesized by a Cu(I)-catalyzed alkyne-azide click reaction for the selective and sensitive detection of cyanide via fluorescence enhancement by ligand exchange and metal ion removal.