Total Synthesis of Saponins of Biological Significance

Biao Yu 한국당과학회 2008 한국당과학회 학술대회 Vol.2008 No.1

Saponins are glycosides of steroids and triterpenes, which exist widely and usually in considerable amount in terrestrial plants and some marine species.1 Numerous saponin extracts from herbal medicinal plants have been applied to treat various human diseases with surprisingly frequent precision, especially in China. Continuous isolation and bioassay of the components have led to the disclosure of many homogeneous saponins possessing significant biological activities. However, little has been known on the structure-activity relationships and the mechanism of action of saponins due to the poor accessibility to homogeneous saponins of various structures in appreciable amounts. This situation calls for chemical synthesis of saponins. The synthesis of saponins requires incorporation of two disparate disciplines of the synthetic chemistry, the synthetic chemistry of steroids/triterpenes and carbohydrates.2 Both disciplines have been the intensive research themes since very early years, however, it was not until 1990s the synthesis of the complex natural saponins became a feasible object and started to attract attention. Here I shall present an account on the total synthesis of natural saponins with potent biological activities. A major concern is the applicability of the contemporary glycosylation and protecting group manipulation protocols on the sophisticated scaffold of steroids and triterpenes.

Lgr4 Promotes Glioma Cell Proliferation through Activation of Wnt Signaling

Yu, Chun-Yong,Liang, Guo-Biao,Du, Peng,Liu, Yun-Hui Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8

The key signaling networks regulating glioma cell proliferation remain poorly defined. The leucine-rich repeat containing G-protein coupled receptor 4 (Lgr4) has been implicated in intestinal, gastric, and epidermal cell functions. We investigated whether Lgr4 functions in glioma cells and found that Lgr4 expression was significantly increased in glioma tissues. In addition, Lgr4 overexpression promoted while its knockdown using small interfering RNA oligos inhibited glioma cell proliferation. In addition, Wnt/${\beta}$-catenin signaling was activated in cells overexpressing Lgr4. Therefore, our results revealed that Lgr4 activates Wnt/${\beta}$-catenin signaling to regulate glioma cell proliferation.

Gearshift characteristics of a two-speed transmission using new electrically controlled toothed band brakes

Biao Ma,Weichen Lu,He Wang,Liang Yu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12

In order to realize the miniaturization and electrification of heavy vehicles, this paper innovatively puts forward a two-speed transmission device equiped with electrically controlled toothed band brakes. The dynamic models of the planetary gear and toothed band brake are derived, and the shift strategy is established to achieve the optimal dynamic performance. Moreover, the gearshift characteristics under different working parameters are studied to verify its feasibility. The results demonstrate that the toothed band brake has a short braking time and contributes to good shift performance, thus has potential for application. The effect of synchronous speed and actuator speed on shift performance is also analyzed. The increase of both speeds is beneficial to speed up the shift time, but lead to increased shift impact. The application of such a brake offers the possibility of full-electric and lightweight for electric vehicles.

Exceptional electrochemical performance of freestanding electrospun carbon nanofiber anodes containing ultrafine SnO_<i>x</i> particles

Zhang, Biao,Yu, Yang,Huang, Zhendong,He, Yan-Bing,Jang, Donghyuk,Yoon, Won-Sub,Mai, Yiu-Wing,Kang, Feiyu,Kim, Jang-Kyo The Royal Society of Chemistry 2012 ENERGY AND ENVIRONMENTAL SCIENCE Vol.5 No.12

<P>SnO<SUB><I>x</I></SUB>–carbon nanofiber (CNF) composites are synthesized using the electrospinning technique for use as freestanding electrodes in Li-ion batteries. The electrodes made from the composites carbonized at 750 °C (SnO<SUB><I>x</I></SUB>–CNF-750) with 14.5 wt% SnO<SUB><I>x</I></SUB> deliver a remarkable capacity of 674 mA h g<SUP>−1</SUP> after 100 cycles when discharged at 0.5 A g<SUP>−1</SUP>. This result is considered the highest among those reported in the literature for anodes made from similar electrospun carbon fibers containing SnO<SUB><I>x</I></SUB> nanoparticles. An increase in carbonization temperature to 950 °C (SnO<SUB><I>x</I></SUB>–CNF-950) results in a significant reduction of the particle content in the fiber due to aggregation of Sn to form nanoparticles external to the fibers, with concomitant degradation of capacities. The presence of amorphous SnO<SUB><I>x</I></SUB> particles at the atomic scale embedded in the conductive CNFs is thought to be responsible for the exceptional electrochemical performance of the SnO<SUB><I>x</I></SUB>–CNF-750 electrodes. These ultrafine particles facilitate the reaction Sn + <I>x</I>Li<SUB>2</SUB>O → SnO<SUB><I>x</I></SUB> + 2<I>x</I>Li<SUP>+</SUP> + 2<I>x</I>e<SUP>−</SUP>, making it highly reversible, which is confirmed by the growing peak currents with increasing scan rate indicated by cyclic voltammetry, and the absence of Sn–Sn bonds in the particles revealed by the extended X-ray absorption fine structure spectroscopy (EXAFS). Both the SnO<SUB><I>x</I></SUB> particle size and content in the fiber play important roles in controlling the rate and cyclic performance of the SnO<SUB><I>x</I></SUB>–CNF composite electrodes.</P> <P>Graphic Abstract</P><P>This paper presents novel SnO<SUB><I>x</I></SUB>–carbon nanofiber composites with embedded ultrafine SnO<SUB><I>x</I></SUB> particles. The composites deliver remarkable power/energy densities as well as excellent cyclic performance due to their high reversibility and stability. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ee23145j'> </P>

Treatment of bladder cancer by geoinspired synthetic chrysotile nanocarrier-delivered circPRMT5 siRNA

Chunping Yu,Yi Zhang,Ning Wang,Wensu Wei,Ke Cao,Qun Zhang,Peiying Ma,Dan Xie,Pei Wu,Biao Liu,Jiahao Liu,Wei Xiang,Xing Hu,Xuewen Liu,Jianfei Xie,Jin Tang,Zhi Long,Long Wang,Hongliang Zeng,Jianye Liu 한국생체재료학회 2022 생체재료학회지 Vol.26 No.1

Background: Circular RNAs (circRNAs) have important functions in many fields of cancer biology. In particular, we previously reported that the oncogenic circRNA, circPRMT5, has a major role in bladder cancer progression. Therapy based on circRNAs have good prospects as anticancer strategies. While anti-circRNAs are emerging as therapeutics, the specific in vivo delivery of anti-circRNAs into cancer cells has not been reported and remains challenging. Methods: Synthesized chrysotile nanotubes (SCNTs) with a relatively uniform length (~ 200 nm) have been designed to deliver an siRNA against the oncogenic circPRMT5 (si-circPRMT5) inhibit circPRMT5. In addition, the antitumor effects and safety evaluation of SCNTs/si-circPRMT5 was assessed with a series of in vitro and in vivo assays. Results: The results showed that SCNTs/si-circPRMT5 nanomaterials prolong si-circPRMT5’s half-life in circulation, enhance its specific uptake by tumor cells, and maximize the silencing efficiency of circPRMT5. In vitro, SCNTs encapsulating si-circPRMT5 could inhibit bladder cancer cell growth and progression. In vivo, SCNTs/si-circPRMT5 inhibited growth and metastasis in three bladder tumor models (a subcutaneous model, a tail vein injection lung metastatic model, and an in situ model) without obvious toxicities. Mechanistic study showed that SCNTs/sicircPRMT5 regulated the miR-30c/SNAIL1/E-adherin axis, inhibiting bladder cancer growth and progression. Conclusion: The results highlight the potential therapeutic utility of SCNTs/si-circPRMT5 to deliver si-circPRMT5 to treat bladder cancer.

A review of the transmission tower-line system performance under typhoon in wind tunnel test

Xianying Li,Yu Yao,Hongtao Wu,Biao Zhao,Bin Chen,Tao Yi 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.2

As a regenerated turbulent wind field process, wind tunnel test has proven to be a promising approach for investigating the transmission tower-line system (TTLS) performance in view of experimental scaled models design, simulation techniques of wind field, and wind induced responses subjected to typhoon. However, the challenges still remain in using various wind tunnels to regenerate turbulent wind field with considerable progress having been made in recent years. This review paper provides an overview of the state-of-the-art of the wind tunnel based on active or passive controlled simulation techniques. Specific attention and critical assessment have been given to: (a) the design of experimental scaled models, (b) the simulation techniques of wind field, and (c) the responses of TTLS subjected to typhoon in wind tunnel. This review concludes with the research challenges and recommendations for future research direction.

Numerical studies on the dynamic characteristics of a wet multi-disc clutch during the disengaging process

Liangjie Zheng,Biao Ma,Man Chen,Liang Yu,Jiaqi Xue 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

A comprehensive numerical model was proposed to investigate the disengaging process of a wet multi-disc clutch, which included the hydrodynamic lubrication, the micro elastic–plastic contact, the spline resistance, and the impact between the piston and clutch hub. The clutch disengaging process was divided into the boundary, mixed, and hydrodynamic lubrication stages to discuss the variations in friction pair gaps and friction torque. Moreover, the nonuniformity coefficient was employed to characterize the disengaging uniformity of friction pair gaps. During the disengaging process, the friction pair gaps increased slowly, increased rapidly, and stabilized after fluctuating. The increase in spline friction coefficient and the decline in pressure decrease rate dramatically deteriorated the disengaging uniformity; the decline in pressure decrease rate also significantly prolonged the disengaging time. This research demonstrated for the first time evidence for the dynamic characteristics of the clutch disengaging process.

Dynamic analysis for gene expression profiles of endothelial colony forming cells under hypoxia

De-Cai Yu,Wen-Du Feng,Xian-Biao Shi,hi-Yong Wang,Wei Ge,Chun-Ping Jiang,Xi-Tai Sun,Yi-Tao Ding 한국유전학회 2013 Genes & Genomics Vol.35 No.4

Previous studies have shown that endothelial colony forming cells (ECFCs) play an important role in the neovascularization of tumors. Hypoxia is emphasized as an important promoter of angiogenesis. However, little is known about genome-wide transcriptional regulation of ECFCs under hypoxic conditions. In this study, gene expression profiles in ECFCswere evaluated under hypoxic conditions for 3, 6, 12, 24,and 48 h, using Affymetrix U133 plus 2.0 chip microarray. 1,103 hypoxia-regulated genes were filtered, with 379(0.693 %) genes up-regulated and 724 (1.32 %) genes downregulated. Most of the up-regulated genes were involved in apoptosis, cell proliferation, or metabolic processes, while most of the down-regulated genes were involved in cell adherence,cell cycle,DNAandmRNAmetabolic processes,multi-cellular organism development, protein metabolic processes, response to stress, signal transduction, or transport. This expression profile is ECFC-specific, because it is significantly different from those of endothelial cells and smooth muscle cells under hypoxic conditions. Moreover, hypoxia-regulated apoptosis in ECFCs is mainly related with the mitochondrial pathway (p53-BAX-Caspase-9) and the death receptor pathway (FASCaspase-8-Caspase-3). MAPK pathway is activated in ECFCs under hypoxic conditions. The differentially expressed genes of ECFCs were identified under hypoxic conditions, and related with cell apoptosis, cell cycle and MAPK pathways, shedding light on the mechanism of angiogenesis.

Temperature Response to Tensile Characteristics of the Hot Asphalt Mixtures

Wei Si,Ning Li,Biao Ma,Yu-xiang Tian,Xue-yan Zhou 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.4

Asphalt concrete is one type of the temperature sensitive mixtures, which is the most and broadest used pavement material in the world. Asphalt pavement suffers from the impact of temperature due to the temperature variation in different districts and environments. Facing temperature sensitivity, this paper uses Indirect Tensile Test (IDT) to analyze the tensile characters of asphalt mixture under different temperatures (-20°C, -10°C, 0°C, 15°C, 20°C, 45°C, and 60°C). The influence factors of temperature, loading rate, asphalt content, asphalt types, and mixtures gradation are evaluated. Piecewise linear model, logarithm linear model and S-logistic nonlinear model are applied to simulate the variation of flexural tensile characters with temperature change. Results show that temperature has significant influence on flexural tensile properties. Loading rates also has obvious influence on flexural tensile characteristics. With temperature changes, asphalt types have evident influence on mixture’s tensile characteristics, SBR modified asphalt has better performance at the lower temperature environment. Mixtures’ gradation has important effect on tensile strength and tensile strain as well, while due the similarity between two gradations, it is hard to precisely recommend which one is better. Asphalt content has evident influence on mixtures properties at the same temperature condition. Research results provide suggestions and applications for construction and performance of asphalt pavement. The results also indicate that IDT would be a practical option to evaluate the properties of asphalt mixture in all temperature ranges.

On Dimensions of Linear Discrete Dimension-unbounded Systems

Jun-e Feng,Biao Wang,Yongyuan Yu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.1

This letter investigates the variance of state dimensions of linear discrete dimension-unbounded systems,which are a class of cross-dimensional systems. First, the dimensional relationship of states, initial values andsystem matrices of some special cases is discussed. Then, for the general case, to directly calculate the transitiontime and state dimensions after the transition time, an algorithm is established on the basis of the iterative time,dimensions of initial values and system matrices. Finally, there is an illustrative example to show the effectivenessof these obtained results