Intelligent Fault Diagnosis of Industrial Robot Based on Multiclass Mahalanobis-Taguchi System for Imbalanced Data

One of the biggest challenges for the fault diagnosis research of industrial robots is that the normal data is far more than the fault data; that is, the data is imbalanced. The traditional diagnosis approaches of industrial robots are more biased toward the majority categories, which makes the diagnosis accuracy of the minority categories decrease. To solve the imbalanced problem, the traditional algorithm is improved by using cost-sensitive learning, single-class learning and other approaches. However, these algorithms also have a series of problems. For instance, it is difficult to estimate the true misclassification cost, overfitting, and long computation time. Therefore, a fault diagnosis approach for industrial robots, based on the Multiclass Mahalanobis-Taguchi system (MMTS), is proposed in this article. It can be classified the categories by measuring the deviation degree from the sample to the reference space, which is more suitable for classifying imbalanced data. The accuracy, G-mean and F-measure are used to verify the effectiveness of the proposed approach on an industrial robot platform. The experimental results show that the proposed approach’s accuracy, F-measure and G-mean improves by an average of 20.74%, 12.85% and 21.68%, compared with the other five traditional approaches when the imbalance ratio is 9. With the increase in the imbalance ratio, the proposed approach has better stability than the traditional algorithms.     

Thermal stress calculations based on a linear viscoelastic deviatoric response and a fictive temperature component for the volumetric response

A temperature dependent thermal expansion coefficient is introduced into the Lee, Rogers and Woo linear viscoelastic model for calculating thermal stresses in glass. Volumetric strain, is calculated as follows: ? = α_liq (T_f - T_O) + α_gl (T - T_f) where α_liq and α_gl are the thermal expansion coefficients for the liquid and glassy states respectively, T is the glass temperature, T_O is the initial temperature, and T_f is the fictive temperature as defined by Tool. Fictive temperatures are calculatedfrom theory and measurements independent of thermal stress experiments. Comparison of calculated with experimentally measured stresses shows that the modified model is useful for predicting thermal tempering propensity for different glass compositions as well as different processing parameters.     

Trichoderma Enzymes for Degradation of Aflatoxin B1 and Ochratoxin A

The contamination of agricultural products with mycotoxins causes risks to animal and human health and severe economic losses. Mycotoxicoses can be reduced by preventing fungal infection using chemical and biological approaches. The chemical strategies can release toxic molecules; therefore, strategies for biological control are being evaluated, such as using nontoxic fungi and their metabolites. This work evaluated the effect of exoenzymes produced by the beneficial fungus Trichoderma afroharzianum strain T22 in degrading Aflatoxin B1 (AFB1) and Ochratoxin A (OTA). The ability of Trichoderma to produce hydrolases was stimulated by using different inducing substrates. The highest AFB1 and OTA degradation activity was obtained using a medium containing lyophilized mushrooms and crude fiber. The T. afroharzianum T22’s ability to reduce mycotoxins may be attributed to peroxidase enzymes. This study showed that T. afroharzianum strain T22 or its peroxidase supplementation could represent a sustainable strategy for the degradation of AFB1 and OTA in feed and food products.     

An unexpected all-metal aromatic tetranuclear silver cluster in human copper chaperone Atox1

Metal clusters, such as iron–sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins. Herein we report the formation and crystal structure of a planar square tetranuclear silver cluster when silver ions were mixed with human copper chaperone Atox1. Quantum chemical studies reveal that two Ag 5s¹ electrons in the tetranuclear silver cluster fully occupy the one bonding molecular orbital, with the assumption that this Ag₄ cluster is Ag₄²⁺, leading to extensive electron delocalization over the planar square and significant stabilization. This bonding pattern of the tetranuclear silver cluster represents an aromatic all-metal structure that follows a 4n + 2 electron counting rule (n = 0). This is the first time an all-metal aromatic silver cluster was observed in a protein.

Metal clusters, such as iron–sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins.     

Preparation and Characterization of Methyl Jasmonate Microcapsules and Their Preserving Effects on Postharvest Potato Tuber

Potato tubers tend to sprout during long-term storage, resulting in quality deterioration and shortened shelf life. Restrictions on the use of chlorpropham, the major potato sprout suppressant, have led to a need to seek alternative methods. In this study, the effects of methyl jasmonate (MeJA) solutions and MeJA microcapsules on sprouting and other key quality attributes of the potato tuber were investigated. The results showed that the MeJA solution was most effective at 300 μmol L⁻¹ according to TOPSIS analysis. To prepare MeJA microcapsules, the optimal formulation is with 0.04% emulsifier, 2.5% sodium alginate, 0.5% chitosan and 3% CaCl₂. Compared to 300 μmol L⁻¹ MeJA solution, MeJA microcapsules consumed a lower dose of MeJA but demonstrated a better retaining effect on the overall quality attributes of potato tubers. MeJA microcapsules are promising agents for the preservation of postharvest potato tubers.     

Faraday-Michelson system for quantum cryptography

Quantum key distribution provides unconditional security for communication. Unfortunately, current experimental schemes are not suitable for long-distance fiber transmission because of phase drift or Rayleigh backscattering. In this Letter we present a unidirectional intrinsically stable scheme that is based on Michelson-Faraday interferometers, in which ordinary mirrors are replaced with 90 degree Faraday mirrors. With the scheme, a demonstration setup was built and excellent stability of interference fringe visibility was achieved over a fiber length of 175 km. Through a 125 km long commercial communication fiber cable between Beijing and Tianjin, the key exchange was performed with a quantum bit-error rate of less than 6%, which is to our knowledge the longest reported quantum key distribution experiment under field conditions.     

Tomatidine-stimulated maturation of human embryonic stem cell-derived cardiomyocytes for modeling mitochondrial dysfunction

Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) have been reported to exhibit immature embryonic or fetal cardiomyocyte-like phenotypes. To enhance the maturation of hESC-CMs, we identified a natural steroidal alkaloid, tomatidine, as a new substance that stimulates the maturation of hESC-CMs. Treatment of human embryonic stem cells with tomatidine during cardiomyocyte differentiation stimulated the expression of several cardiomyocyte-specific markers and increased the density of T-tubules. Furthermore, tomatidine treatment augmented the number and size of mitochondria and enhanced the formation of mitochondrial lamellar cristae. Tomatidine treatment stimulated mitochondrial functions, including mitochondrial membrane potential, oxidative phosphorylation, and ATP production, in hESC-CMs. Tomatidine-treated hESC-CMs were more sensitive to doxorubicin-induced cardiotoxicity than the control cells. In conclusion, the present study suggests that tomatidine promotes the differentiation of stem cells to adult cardiomyocytes by accelerating mitochondrial biogenesis and maturation and that tomatidine-treated mature hESC-CMs can be used for cardiotoxicity screening and cardiac disease modeling.Subject terms: Heart failure, Embryonic stem cells, Stem-cell differentiation     

Bioavailability Enhancement of Cepharanthine via Pulmonary Administration in Rats and Its Therapeutic Potential for Pulmonary Fibrosis Associated with COVID-19 Infection

Cepharanthine (CEP) has excellent anti-SARS-CoV-2 properties, indicating its favorable potential for COVID-19 treatment. However, its application is challenged by its poor dissolubility and oral bioavailability. The present study aimed to improve the bioavailability of CEP by optimizing its solubility and through a pulmonary delivery method, which improved its bioavailability by five times when compared to that through the oral delivery method (68.07% vs. 13.15%). An ultra-performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS) method for quantification of CEP in rat plasma was developed and validated to support the bioavailability and pharmacokinetic studies. In addition, pulmonary fibrosis was recognized as a sequela of COVID-19 infection, warranting further evaluation of the therapeutic potential of CEP on a rat lung fibrosis model. The antifibrotic effect was assessed by analysis of lung index and histopathological examination, detection of transforming growth factor (TGF)-β1, interleukin-6 (IL-6), α-smooth muscle actin (α-SMA), and hydroxyproline level in serum or lung tissues. Our data demonstrated that CEP could significantly alleviate bleomycin (BLM)-induced collagen accumulation and inflammation, thereby exerting protective effects against pulmonary fibrosis. Our results provide evidence supporting the hypothesis that pulmonary delivery CEP may be a promising therapy for pulmonary fibrosis associated with COVID-19 infection.