Pestalotiolide A, a New Antiviral Phthalide Derivative from a Soft Coral-derived Fungus Pestalotiopsis sp.

Yan-Lai Jia,Fei-Fei Guan,Jie Ma,Chang-Yun Wang,Chang-Lun Shao 한국생약학회 2015 Natural Product Sciences Vol.21 No.4

Chemical investigation of the fermentation broth of a Soft Coral-Derived fungus Pestalotiopsis sp., led to the isolation of a new phthalide derivative, pestalotiolide A (1), three known analogues (2, 3 and 4), along with 5'-O-acetyl uridine (5) first isolated as a natural product. The structure of the new compound (1) was established by comprehensive spectroscopic analysis and chemical methods. Compounds 1 - 4 possessed varying degrees of antiviral activities, which was reported for the first time. Compared to the positive control ribavirin (IC50 = 418.0 μM), pestalotiolide A (1) exhibited significant anti-EV71 activity in vitro, with an IC50 value of 27.7 mM. Furthermore, the preliminary structure-activity relationship of antiviral activities was also discussed.

Developments of double skin composite walls using novel enhanced C-channel connectors

Jia-Bao Yan,An-Zhen Chen,Tao Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.6

The developments of double skin composite (DSC) walls with novel enhanced C-channel connectors (DSCW-EC) were reported. Followed axial compression tests on prototype walls were carried to evaluate structural performances of this novel DSC composite structures. The testing program consists of five specimens and focused on the layout of the novel enhanced C-channel (EC) connectors, which include the web direction of C-channels, steel-faceplate thickness, vertical and horizontal spacing of Cchannels. Crushing in concrete core and buckling of steel faceplate were two main observed failed modes from the compression tests. However, elastic or plastic buckling of the steel faceplate varies with designed parameters in different specimens. The influences of those investigated parameters on axial compressive behaviors of DSCW-ECs were analyzed and discussed. Recommendations on the layout of novel EC connectors were then given based on these test results and discussions. This paper also developed analytical models for predictions on ultimate compressive resistance of DSCW-ECs. Validation against the reported test results show that the developed theoretical models predict well the ultimate compressive resistance of DSCW-ECs.

Preparation of Silver Metallic Sponge from Macroporous Carbon Template

Yan, Jia,Wang, An Jie,Kim, Dong Pyo Trans Tech Publications, Ltd. 2006 Materials science forum Vol.510 No.-

<P>Silver-containing porous frameworks have been extensively used in catalysis, electrochemistry, for heat dissipation and biofiltration. In this study, porous silver sponge was prepared by using a sacrificial macroporous carbon template. Aqueous AgNO3 was infiltrated into the carbon template and reduced to Ag by borohydride reduction reaction, followed by burning of the sacrificial template in air at 500~650°C. The products were characterized by SEM, XRD, and N2 adsorption-desorption isotherms. The Ag sponge exhibited a BET surface area of 12 m2/g.</P>

Insight into substituent effects on the hydrolysis of amidines by a microhydration model

Jia, Yan,Xiao, Hong,Li, Ying Li,Bai, Qun Hua,Xue, Ying,Kim, Chan Kyung,Gao, Jie Ying Springer-Verlag 2017 Theoretical chemistry accounts Vol.136 No.6

A NEW LOOK AT THE FUNDAMENTAL THEOREM OF ASSET PRICING

Yan, Jia-An Korean Mathematical Society 1998 대한수학회지 Vol.35 No.3

In this paper we consider a security market whose asset price process is a vector semimartingale. The market is said to be fair if there exists an equivalent martingale measure for the price process, deflated by a numeraire asset. It is shown that the fairness of a market is invariant under the change of numeraire. As a consequence, we show that the characterization of the fairness of a market is reduced to the case where the deflated price process is bounded. In the latter case a theorem of Kreps (1981) has already solved the problem. By using a theorem of Delbaen and Schachermayer (1994) we obtain an intrinsic characterization of the fairness of a market, which is more intuitive than Kreps' theorem. It is shown that the arbitrage pricing of replicatable contingent claims is independent of the choice of numeraire and equivalent martingale measure. A sufficient condition for the fairness of a market, modeled by an Ito process, is given.

Probiotics: The Next Dietary Strategy against Brain Aging

Jia-Sin Ong,Lee-Ching Lew,Yan-Yan Hor,Min-Tze Liong 한국식품영양과학회 2022 Preventive Nutrition and Food Science Vol.27 No.1

Owing to their long history of safe use, probiotic microorganisms, typically from the genus Lactobacillus, have long been recognized, especially in traditional and fermented food industries. Although conventionally used for dairy, meat, and vegetable fermentation, the use of probiotics in health foods, supplements, and nutraceuticals has gradually increased. Over the past two decades, the importance of probiotics in improving gut health and immunity as well as alleviating metabolic diseases has been recognized. The new concept of a gut-heart-brain axis has led to the development of various innovations and strategies related to the introduction of probiotics in food and diet. Probiotics influence gut microbiota profiles, inflammation, and disorders and directly impact brain neurotransmitter pathways. As brain health often declines with age, the concept of probiotics being beneficial for the aging brain has also gained much momentum and emphasis in both research and product development. In this review, the concept of the aging brain, different in vivo aging models, and various aging-related benefits of probiotics are discussed.

Behaviors of novel sandwich composite beams with normal weight concrete

Jia-Bao Yan,Xin Dong,Tao Wang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.5

The ultimate strength behaviour of sandwich composite beams with J-hooks and normal weight concrete (SCSSBJNs) are studied through two-point loading tests on ten full-scale SCSSBJNs. The test results show that the SCSSBJN with different parameters under two-point loads exhibits three types of failure modes, i.e., flexure, shear, and combined shear and flexure mode. SCSSBJN failed in different failure modes exhibits different load-deflection behaviours, and the main difference of these three types of behaviours exist in their last working stages. The influences of thickness of steel faceplate, shear span ratio, concrete core strength, and spacing of J-hooks on structural behaviours of SCSSBJN are discussed and analysed. These test results show that the failure mode of SCSSBJN was sensitive to the thickness of steel faceplate, shear span ratio, and concrete core strength. Theoretical models are developed to estimate the cracking, yielding, and ultimate bending resistance of SCSSBJN as well as its transverse cross-sectional shear resistance. The validations of predictions by these theoretical models proved that they are capable of estimating strengths of novel SCSSBJNs.

Tensile behavior of stainless steel S30408 at the Arctic low temperature

Jia-Bao Yan,Zhicheng Lin,Peng Xie,Yun-Biao Luo,Yanbo Li 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5

This paper investigated tensile behaviours of S30408 at the Arctic low temperatures (T) of -80~20℃. A cooling chamber equipped with liquid nitrogen gas was adopted to rebuild the Arctic low-temperature environment. Standard tension tests were performed on 48 coupons with different thickness at different T values of -80, -60, -30, and 20℃. Test results revealed the ductile failure mode of stainless steel S30408 even at -80℃. The tensile stress-strain (σ-ε) curves of S30408 at ambient temperatures exhibited a long strain hardening plateau. Meanwhile, the low-temperature tensile σ-ε curves of S30408 were different from those at ambient temperatures, which exhibited a second hardening stage with a larger slope than the first hardening. The decreasing T generally increased the elastic modulus, yield and ultimate strength, but reduced the ductility of S30408. Decreasing the T from 20 to -80℃ reduced the ductility of S30408 by about 28%, but improved the elastic modulus, yield and ultimate strength by about 20%, 22%, and 75%, respectively. This paper also adopted the best subset regression analysis method to develop empirical formulae on estimating influences of T on mechanical properties of S30408. Validations of the predictions by these empirical formulae against the test results in the literature proved their accuracies.

Shear and tensile behaviors of headed stud connectors in double skin composite shear wall

Jia-Bao Yan,Zhe Wang,Tao Wang,Xiao-Ting Wang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.6

This paper studies shear and tensile behaviors of headed stud connectors in double skin composite (DSC) structure. Firstly, 11 push-out tests and 11 tensile tests were performed to investigate the ultimate shear and tensile behaviors of headed stud in DSC shear wall, respectively. The main parameters investigated in this test program were height and layout of headed stud connectors. The test results reported the representative failure modes of headed studs in DSC structures subjected to shear and tension. The shear-slip and tension-elongation behaviors of headed studs in DSC structures were also reported. Influences of different parameters on these shear-slip and tension-elongation behaviors of headed studs were discussed and analyzed. Analytical models were also developed to predict the ultimate shear and tensile resistances of headed stud connectors in DSC shear walls. The developed analytical model incorporated the influence of the dense layout of headed studs in DSC shear walls. The validations of analytical predictions against 22 test results confirmed the accuracy of developed analytical models.

Ketamine induces neuronal apoptosis and cognitive disorder via miR-199a-5p/HIF-1α in neonatal rats

Jia Yan,Yue Yu,Yu Sun,Rong Hu,Hong Jiang 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.4

It reported that repeated administration of clinical doses of ketamine could induce neuronal apoptosis in the immature brain. In this study, SpragueDawley postnatal day 7 rats were treated with ketamine. As the rats grew, we found ketamine impaired the cognitive function of the rats. Ketamine increased HIF1α level in the brain tissues of rats as compared to the control group and YC-1 rescued those effects. The escape latency and the platform crossing time of Morris water maze decreased in the YC-1-treated rats compared to the control in ketamine-treated rats. We also found that ketamine decreased the expression of miR199a-5p and HIF-1α is a directly target of miR-199a5p. Administration of ketamine also decrease the cell activity while YC-1 and MiR-199a-5p mimics rescued the inhibition effect. In conclusion, we suggest that ketamine-induced neuronal apoptosis in neonatal rats, followed by learning and memory impairment, might be mediated via the miR-199a-5p/HIF-1α signalling pathway.