Abstract
Viscoelastic materials (VEMs) made from rubber polymer will inevitably age due to the interactions with the harmful environment during service life, thus reducing the reliability of ...viscoelastic (VE) damping equipment installed in building structures. In order to understand and be able to predict the degradation of VE damping equipment, it is imperative to comprehensively study the influence of aging on the mechanical properties of VEMs. In this paper, a series of thermal‐oxidative (TO) aging tests and mechanical property tests are conducted on our previously developed VEMs to study effects of TO aging on the molecular chain structure and corresponding changes of macroscopic mechanical properties of VEMs. By classifying molecular chains of VEMS into elastic chains and free chains, the effects of different chemical reactions during TO aging on these two main chains and corresponding changes on macroscopic mechanical behaviors of VEMs are analyzed. This facilitates formulating a mathematical model that can characterize the mechanical behavior of TO aging VEMs. In conjunction with the experimental data, the accuracy and applicability of the proposed model are compared and verified. Sensitivity analyses of parameters involved in the proposed model are then performed. The experimental results demonstrate that the TO aging can degrade the deformation capability and harden the modulus of VEMs, which may adversely affect the performance of VE damping devices. The parameter analyses depict that the TO aging affects the macroscopic mechanical behavior of VEMs by altering the relative number and configuration of free chains and elastic chains as well as their respective contributions to the total stress of VEMs. The results point to the high accuracy of the proposed model in representing the strain–stress behavior of VEMs under different aging conditions.
Orchidaceae, renowned for its spectacular flowers and other reproductive and ecological adaptations, is one of the most diverse plant families. Here we present the genome sequence of the tropical ...epiphytic orchid Phalaenopsis equestris, a frequently used parent species for orchid breeding. P. equestris is the first plant with crassulacean acid metabolism (CAM) for which the genome has been sequenced. Our assembled genome contains 29,431 predicted protein-coding genes. We find that contigs likely to be underassembled, owing to heterozygosity, are enriched for genes that might be involved in self-incompatibility pathways. We find evidence for an orchid-specific paleopolyploidy event that preceded the radiation of most orchid clades, and our results suggest that gene duplication might have contributed to the evolution of CAM photosynthesis in P. equestris. Finally, we find expanded and diversified families of MADS-box C/D-class, B-class AP3 and AGL6-class genes, which might contribute to the highly specialized morphology of orchid flowers.
To improve the physicochemical stability of hydrophobic flavonoids, a series of protein-based nanomicelles have been developed in recent years. However, the quinoa protein (QP) nanomicelles and its ...interactions with different flavonoids were rarely reported. In this study, the QP nanomicelles (48.6 nm) were initially prepared. Then, quercetin (Que), curcumin (Cur), luteolin (Lut) and resveratrol (Res) were successfully assembled into the hydrophobic region of QP nanomicelles, giving the loading capacity of 33.9%, 8.0%, 17.8% and 6.4%, respectively. Moreover, this self-assembly significantly enhanced the solubility and stability of four flavonoids. The molecular interactions were further investigated. Results showed that hydrophobic interaction and hydrogen bonding were the main interaction driving forces between QP and hydrophobic flavonoids. The present work provided valuable evidences for the application of quinoa protein in functional foods.
Display omitted
•Quinoa protein (QP) was extracted from quinoa seeds.•Hydrophobic flavonoids were successfully assembled in QP nanomicelles.•Flavonoids inducing the fluorescence quenching of QP via self-assembly.•Hydrophobic interaction and hydrogen bonding were the main molecular driving forces.
α,β‐Unsaturated compounds are one of the most important functional compounds. Due to their unique property and versatile utility, they usually occur as the key intermediates for the synthesis of ...pharmaceuticals and biological materials. Thus, their synthesis has attracted more attentions than before. The early approaches to α,β‐unsaturated compounds are mainly about transition‐metal‐free methods, such as halogenation‐dehydrohalogenation methods and strong oxidants methods (organosulfur, organoselenium, benzoquinone). Subsequently, palladium and the other transition‐metals catalyzed dehydrogenation of carbonyl compounds appeared respectively. In this review, transition‐metal‐catalyzed α,β‐dehydrogenation is discussed, which is categorized by functional groups.
α,β‐Unsaturated compounds are one of the most important functional compounds. They usually occur as the key intermediates for the synthesis of pharmaceuticals and biological materials The early approaches to α,β‐unsaturated compounds are mainly about transition‐metal‐free methods, such as halogenation‐dehydrohalogenation methods and strong oxidants methods. This review mainly focuses on transition‐metal‐catalyzed α,β‐dehydrogenation, which is categorized by functional groups.
The Aerides-Vanda alliance is a complex group in the subtribe Aeridinae (subfamily Epidendroideae, Orchidaceae). Some phylogenetic systems of this alliance have been previously proposed based on ...molecular and morphological analyses. However, several taxonomic problems within this alliance as well as between it and its allies remain unsolved.
We utilized ITS and five plastid DNA regions in this phylogenetic analysis. Consensus trees strongly indicate that the Aerides-Vanda alliance is monophyletic, and the 14 genera of this alliance can be grouped into the following clades with 14 subclades: 1. Aerides, comprising two subclades: Rhynchostylis and Aerides; 2. Ascocentropsis; 3. Papilionanthe; 4. Vanda, comprising five subclades: Neofinetia, Christensonia, Seidenfadenia, Ascocentrum, and Vanda-Trudelia, in which Vanda and Trudelia form a subclade; 5. Tsiorchis, comprising three subclades: Chenorchis, Tsiorchis, and two species of Ascocentrum; 6. Paraholcoglossum; and 7. Holcoglossum. Among the 14 genera, only Ascocentrum is triphyletic: two species of the Ascocentrum subclade, an independent subclade Ascocentrum subclade in the Tsiorchis clade; the Ascocentrum subclade in the Vanda clade; and one species in the Holcoglossum clade. The Vanda and Trudelia species belong to the same subclade. The molecular conclusion is consistent with their morphological characteristics.
We elucidate the relationship among the 14 genera of the Aerides-Vanda alliance. Our phylogenetic results reveal that the Aerides-Vanda alliance is monophyletic, but it can be divided into 14 genera. The data prove that Ascocentrum is triphyletic. Plants with elongate-terete leaves and small flowers should be treated as a new genus, Pendulorchis. Saccolabium himalaicum (Ascocentrum himalaicum) should be transferred to Pendulorchis. Ascocentrum pumilum, endemic to Taiwan, should be transferred to Holcoglossum. A new combination, Holcoglossum pumilum, was also established. Trudelia should not be recognized as an independent genus. Two new species, Pendulorchis gaoligongensis and Holcoglossum singchianum, were described as well.
Display omitted
•Comprehensive nutrients profiling of bee pollen with various botanical and geographic origins were reviewed.•Active natural plant metabolites from bee pollen and their in vivo ...metabolic pathways were summarized.•The nutritional values of bee pollen and its potential bioactivities for human health were updated.•The safety of bee pollen as a food supplement was highlighted.
Bee pollen is a mixture of plant pollen pellet with nectar and honeybee secretions. Due to its active natural metabolites with extensive nutritional and therapeutic properties, it is recommended as a treasure trove of human nutrition. The nutritional components in bee pollen include carbohydrates, proteins, lipids, vitamins, minerals, polyphenols, and a small percentage of other components. Previous studies demonstrated that bee pollen exhibit antioxidant, antibacterial, anti-inflammatory, anticarcinogenic, and antiallergic properties. This comprehensive review focused on the nutritional properties and potentially active phytometabolites (polyphenolic acids and flavonoids) of bee pollen and its therapeutic health benefits. We also covered the food safety and guidelines for the consumption with future industrial challenges of bee pollen.
Monolithic integration of III-V on silicon has been a scientifically appealing concept for decades. Notable progress has recently been made in this research area, fueled by significant interests of ...the electronics industry in high-mobility channel transistors and the booming development of silicon photonics technology. In this review article, we outline the fundamental roadblocks for the epitaxial growth of highly mismatched III-V materials, including arsenides, phosphides, and antimonides, on (001) oriented silicon substrates. Advances in hetero-epitaxy and selective-area hetero-epitaxy from micro to nano length scales are discussed. Opportunities in emerging electronics and integrated photonics are also presented.
Herba Epimedii is an important medicinal plant which has been used in various traditional Chinese formulations for thousands of years as well as in modern proprietary traditional Chinese medicine ...products. It has extensive clinical indications, especially for the treatment of sexual dysfunction and osteoporosis. There have been more than 260 chemical moieties identified in the genus Epimedium most of which belong to flavonoids. Icariin is the most abundant constituent in Herba Epimedii. Icariin is pharmacologically bioactive and demonstrates extensive therapeutic capacities such as osteoprotective effect, neuroprotective effect, cardiovascular protective effect, anti-cancer effect, anti-inflammation effect, immunoprotective effect and reproductive function. Particularly, the significant osteogenic effect of icariin made it a promising drug candidate in bone tissue engineering. The current review paper aims to summarize the literatures reporting the pharmacological effects of icariin. The pharmacokinetic properties of bioactive ingredients in Herba Epimedii have also been discussed.
Display omitted
The incidence of myopericarditis after mRNA COVID-19 vaccination among adolescents aged 12–17 years remains unknown. Therefore, we conducted a study to pool the incidence of myopericarditis following ...COVID-19 vaccination in this age group.
We did a meta-analysis by searching 4 electronic databases until February 6, 2023. The following main keywords were used: “COVID-19”, “vaccines”, “myocarditis”, “pericarditis”, and “myopericarditis”. Observational studies reporting on adolescents aged 12–17 years who had myopericarditis in temporal relation to receiving mRNA COVID-19 vaccines were included. The pooled incidence of myopericarditis and 95 % confidence interval (CI) were calculated using a single-group meta-analysis.
Fifteen studies were included. The pooled incidences of myopericarditis after mRNA COVID-19 vaccination among adolescents aged 12–17 years were 43.5 (95 % CI, 30.8–61.6) cases per million vaccine doses for both BNT162b2 and mRNA-1273 (39 628 242 doses; 14 studies), and 41.8 (29.4–59.4) cases for BNT162b2 alone (38 756 553 doses; 13 studies). Myopericarditis was more common among males (66.0 40.5–107.7 cases) than females (10.1 6.0–17.0 cases) and among those receiving the second dose (60.4 37.6–96.9 cases) than those receiving the first dose (16.6 8.7–31.9 cases). The incidences of myopericarditis did not differ significantly when grouped by age, type of myopericarditis, country, and World Health Organization region. None of the incidences of myopericarditis pooled in the current study were higher than those after smallpox vaccinations and non-COVID-19 vaccinations, and all of them were significantly lower than those in adolescents aged 12–17 years after COVID-19 infection.
The incidences of myopericarditis after mRNA COVID-19 vaccination among adolescents aged 12–17 years were very rare; they were not higher than other important reference incidences. These findings provide an important context for health policy makers and parents with vaccination hesitancy to weight the risks and benefits of mRNA COVID-19 vaccination among adolescents aged 12–17 years.
PDF
