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Poor electrical connections contribute to electrical fires. The ignition process due to poor electrical contacts was studied and revealed the triggering mechanisms at crucial stages. By manipulating the contact resistance to simulate real-world poor connection scenarios, three distinct stages were identified in the ignition process. Stage I, referred to as temperature rise and pyrolysis, is attributed to high resistance at electrical contacts. Stage II, referred to as arc-accelerated pyrolysis, is the complete formation of a carbonized path due to insulation breakdown, and Stage III, referred to as ignition and combustion, is the ignition of pyrolysis gases by the arc on the carbonized path. The duration of Stages I and II is strongly correlated with the electrical contact power (Q̇cR) and the arc power (Q̅arc). The transition from Stage I to Stage II occurs at a critical electrical contact power of 35 W. Two critical thresholds exist for the transition from Stage II to Stage III: an ignition threshold Q̅arc1(about 50 W), and an extremely easy ignition threshold Q̅arc2(about 250 W), both determined by the initial fire core control volume energy formed by pyrolysis gases and the arc, and by the surrounding environment. Fault development pathways in electrical connectors and key parameter changes were identified, providing support for enhancing electrical safety inspections and risk prevention strategies.

Neutron conversion detectors that use 10B-enriched boron carbide are feasible alternatives to 3He-based detectors. We prepared boron carbide films at micron-scale thickness using direct-current magnetron sputtering. The structural characteristics of natural B4C films, including density, roughness, crystallization, and purity, were analyzed using grazing incidence X-ray reflectivity, X-ray diffraction, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and scanning electron microscopy. A beam profile test was conducted to verify the practicality of the 10B-enriched B4C neutron conversion layer. A clear profile indicated the high quality of the neutron conversion of the boron carbide layer.

In this paper, an intelligent decision-making framework (DMF) is developed to help decision makers identify cost-effective ozone control policies. High concentrations of ozone at the ground level continue to be [...]

Background: Oleanolic Acid (OA) is a ubiquitous product of triterpenoid compounds. Due to its inexpensive availability, unique bioactivities, pharmacological effects and non-toxic properties, OA has attracted tremendous interest in the field of drug design and synthesis. Furthermore, many OA derivatives have been developed for ameliorating the poor water solubility and bioavailability. Objective: Over the past few decades, various modifications of the OA framework structure have led to the observation of enhancement in bioactivity. Herein, we focused on the synthesis and medicinal performance of OA derivatives modified on A-ring. Moreover, we clarified the relationship between structures and activities of OA derivatives with different functional groups in A-ring. The future application of OA in the field of drug design and development also was discussed and inferred. Conclusion: This review concluded the novel achievements that could add paramount information to the further study of OA-based drugs.

Studies have shown that the m6A reader primarily affects genes expression by participating in the regulation of mRNA localization, splicing, degradation, translation, and other metabolic processes. Previously, we discovered that the apple (Malus domestica) m6A reader MhYTP2 bound with and destabilized m6A-modified MdMLO19mRNA. In addition, it enhanced the translation efficiency of m6A-modified mRNA of MdGDH1L, encoding a glutamate dehydrogenase, which confers resistance to powdery mildew. In this study, we report the function of MhYTP2 in the regulation of resistance to low nitrogen (N). The overexpression of MhYTP2enhances the resistance of apple to low N. We show that MhYTP2 binds with and stabilizes the mRNAs of MdALN, which participates in the allantoin catabolic process and cellular response to N starvation in apple; MdPIDL, which participates in root hair elongation; MdTTG1, which is involved in the differentiation process of trichomes; and MdATG8A, which is a core participant in the regulation of autophagy. In addition, MhYTP2 accelerates the degradation of MdRHD3mRNA, which regulates root development. RNA immunoprecipitation-seq and electrophoretic mobility shift assays show that the mRNAs of MdALN, MdATG8A, MdPIDL, MdTTG1, and MdRHD3are the direct targets of MhYTP2. Overexpressing or knocking down the above genes in MhYTP2overexpressing plants dismisses the function of MhYTP2 under low N, suggesting the role of MhYTP2 is dependent on those genes. Together, these results demonstrate that MhYTP2 enhances the resistance of apple to N deficiency by affecting the stability of the bound mRNAs.

The article offers information on the use of algae glue and nonwoven paper during the conservation and restoration of Chinese paintings and calligraphies. The author discusses the use of oil paper to protect silk works during the restoration process, the types of algae and nonwoven paper used, and treating the large trompe l'œil silk paintings placed on the ceiling and walls of the main hall Juanqin zhai located in the Forbidden City (Beijing, China).

Extraordinary optical transmission (EOT) in subwavelength metal structures has been studied widely. Herein, we propose a strategy for tuning the EOT of the bullseye structure. Specifically, the bullseye structure was immersed in a nonlinear medium, and a controlling light was employed to change the refractive index of the medium. At different intensities and distributions of controlling light, the transmission property of signal light in the bullseye structure was simulated. The results show that a variable transmission spectrum in the bullseye structure can be realized. Moreover, the position of the central transmission peak shifts linearly with the increasing intensity of controlling light.

Chrysin, a flavonoid, has played a great role in the fields of anticancer, antibacterial, and antiviral drug discovery. A large number of chrysin derivatives have been synthesized recently. The fluorine atom represents an important substituent group for a great number of natural products and pharmaceuticals. Taking into account the importance of both chrysin and the fluorine atom in medicinal chemistry, the synthesis of fluorine-containing chrysin derivatives has gained great interest. Chemically, the synthetic methods for these new chrysin derivatives have also been developed rapidly. In recent years, research on their synthesis has been focused on speeding up the reaction process by changing the catalyst. Biologically, the purpose of introducing fluorine into chrysin was to improve its lipophilicity, but today it is mainly focused on the enhancement and improvement of either its anticancer or antimicrobial activities by incorporating the special properties of fluorine atoms. In this review, synthetic methods for the introduction of fluorine atoms into chrysin are summarized, and their anticancer, antibacterial, antiviral, and hypoglycemic effects are discussed.

An intelligent handheld terminal for campus was designed to meet the teaching management requirements under the new education situation. This system is composed of fingerprint identification module, wireless communication module, LCD touch screen module and embedded system. So, it can achieve multiple functions. Specifically, we design the hardware schematic diagram and PCB, then devise driver and transplant FreeRTOS operating system according to the working characteristic of each module. The communication protocol between the handheld terminal and the host computer is designed to complete the process of collecting fingerprint attendance and classroom test data and then transmitting those data wirelessly to the host computer. This system will be helpful to improve the campus service and teaching quality.