Vibratory characteristics of cracked non-uniform beams with different boundary conditions

Han-bing Liu,Zhigang Wei,Guojin Tan,Yangyang Han,Ziyu Liu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Non-uniform beams with bending moment of inertia and mass per unit length varying as I(x) = α 1 (1+βx) λ+4 and m(x) = α 2 (1+βx) λ are widely used in various engineering fields, such as the civil and mechanical engineering etc. This paper presents an exact method to investigate the free vibration of cracked non-uniform beams with different conditions. Firstly, the closed form solution for the mode shape functions of the non-uniform beam is obtained based on the Euler-Bernoulli beam theory. Secondly, the beam is divided into several segments according to the different variable form, and each segment is further divided into many sub-segments by cracks. Four undetermined coefficients could represent the mode shape function of each sub-segment by simulating crack with the massless rotational spring. The undetermined transfer relationship in the same segment is obtained based on the principle of the transfer matrix method. The fourorder undetermined coefficient matrix is obtained by using continuity and equilibrium conditions between adjacent segments, and then the characteristic equation of the entire cracked beam is obtained after that. Finally, the results obtained from the finite element method and published papers are used to validate the correctness and reliability of the proposed method. The influences of crack depth, location and boundary conditions on natural frequencies of cracked non-uniform beams are discussed.

Effect of temperature and spring-mass systems on modal properties of Timoshenko concrete beam

Han-bing Liu,Hua Wang,Guojin Tan,Wensheng Wang,Ziyu Liu 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4

An exact solution for the title problem was obtained in closed-form fashion considering general boundary conditions. The expressions of moment, shear and shear coefficient (or shear factor) of cross section under the effect of arbitrary temperature distribution were first derived. In view of these relationships, the differential equations of Timoshenko beam under the effect of temperature were obtained and solved. Second, the characteristic equations of Timoshenko beam carrying several spring-mass systems under the effect of temperature were derived based on the continuity and force equilibrium conditions at attaching points. Then, the correctness of proposed method was demonstrated by a Timoshenko laboratory beam and several finite element models. Finally, the influence law of different temperature distribution modes and parameters of spring-mass system on the modal characteristics of Timoshenko beam had been studied, respectively.

Controllable Synthesis of Stereoregular Polyesters by Organocatalytic Alternating Copolymerizations of Cyclohexene Oxide and Norbornene Anhydrides

Han, Bing,Zhang, Li,Liu, Binyuan,Dong, Xiaofang,Kim, Il,Duan, Zhongyu,Theato, Patrick American Chemical Society 2015 Macromolecules Vol.48 No.11

<P>A facile strategy has been demonstrated for the selective synthesis of highly stereoregular polyesters with <I>cis</I>-2,3-(<I>exo</I>,<I> exo</I>) or <I>trans</I>-2,3-(<I>exo</I>,<I> endo</I>) repeating units by the organocatalysts mediated alternating copolymerization of cyclohexene oxide and norbornene anhydride (NA) stereoisomers. The geometrical structure of polyester can be tuned simply by modulating the type of NA isomers (<I>endo</I>- or <I>exo</I>-NA), monomer feed ratio, and reaction temperature. The <I>cis</I>- (>99%) and <I>trans</I>-polyesters (>99%) exhibit high glass transition temperature up to 129.8 and 115.9 °C, respectively. The resulting polyesters provide a versatile platform to incorporate various functional groups through the robust thiol–ene reaction of the pendant norbornenyl groups.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2015/mamobx.2015.48.issue-11/acs.macromol.5b00555/production/images/medium/ma-2015-00555x_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma5b00555'>ACS Electronic Supporting Info</A></P>

Cytisine, a Partial Agonist of α4β2 Nicotinic Acetylcholine Receptors, Reduced Unpredictable Chronic Mild Stress-Induced Depression-Like Behaviors

Han, Jing,Wang, Dong-sheng,Liu, Shui-bing,Zhao, Ming-gao The Korean Society of Applied Pharmacology 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.3

Cytisine (CYT), a partial agonist of ${\alpha}4{\beta}2-nicotinic$ receptors, has been used for antidepressant efficacy in several tests. Nicotinic receptors have been shown to be closely associated with depression. However, little is known about the effects of CYT on the depression. In the present study, a mouse model of depression, the unpredictable chronic mild stress (UCMS), was used to evaluate the activities of CYT. UCMS caused significant depression-like behaviors, as shown by the decrease of total distances in open field test, and the prolonged duration of immobility in tail suspension test and forced swimming test. Treatment with CYT for two weeks notably relieved the depression-like behaviors in the UCMS mice. Next, proteins related to depressive disorder in the brain region of hippocampus and amygdala were analyzed to elucidate the underlying mechanisms of CYT. CYT significantly reversed the decreases of 5-HT1A, BDNF, and mTOR levels in the hippocampus and amygdala. These results imply that CYT may act as a potential anti-depressant in the animals under chronic stress.

Black Hole Mass and Accretion Rate of Active Galactic Nuclei

Xue-Bing Wu,F.K. Liu,J.L. Han,M.Z. Kong,R. Wang 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4

The determination of the central black hole mass is crucial to the understanding of active galactic nuclei physics. In this paper, we brie°y review some methods that are currently used to estimate the black hole mass of AGNs. Particularly, we demonstrate the importance of two correlations: one between the black hole mass and the stellar velocity dispersion and the other one between the broad line region (BLR) size and the optical continuum luminosity. Besides applying these relations in deriving the black hole masses of various types of AGNs, we also employ the fundamental plane of elliptical galaxies to estimate the central velocity dispersions of AGN host galaxies, and then the black hole masses of AGNs, including BL Lac objects. In addition, we derive another empirical relation between the BLR size and the H. emission line luminosity from AGNs with the BLR size measured by reverberation mapping studies, and we argue that more accurate black hole masses of extremely radio-loud AGNs can be obtained with it than by using the usual R ¡ L 5100ºA relation because of the jet contribution to the optical continuum. Finally, we point out that black hole mass estimation is very much helpful in determining the accretion rate and in understanding the accretion process in AGNs.

Recovery of zinc and iron from high iron-bearing zinc calcine by selective reduction roasting

Junwei Han,Wei Liu,Wenqing Qin,Bing Peng,Kang Yang,Yongxing Zheng 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-

A novel method to recover zinc and iron from high iron-bearing zinc calcine by reduction roasting-lowacid leaching-magnetic separation was proposed. The effects of roasting and leaching conditions wereinvestigated and their optimum conditions were established. Meanwhile, the mineralogical changesduring the processes were characterized by XRD, VSM, SEM and LPSA. The results show the ZnFe2O4 inthe calcine was decomposed into ZnO and Fe3O4, and about 92.6% Zn was extracted from the roastedcalcine with reporting most of iron as magnetite into the residue. Finally, more than 90% Fe wasrecovered from the residue by magnetic separation method.

Cytisine, a Partial Agonist of α4β2 Nicotinic Acetylcholine Receptors, Reduced Unpredictable Chronic Mild Stress-Induced Depression-Like Behaviors

( Jing Han ),( Dong Sheng Wang ),( Shui Bing Liu ),( Ming Gao Zhao ) 한국응용약물학회 2016 Biomolecules & Therapeutics(구 응용약물학회지) Vol.24 No.3

Cytisine (CYT), a partial agonist of α4β2-nicotinic receptors, has been used for antidepressant efficacy in several tests. Nicotinic receptors have been shown to be closely associated with depression. However, little is known about the effects of CYT on the depression. In the present study, a mouse model of depression, the unpredictable chronic mild stress (UCMS), was used to evaluate the activities of CYT. UCMS caused significant depression-like behaviors, as shown by the decrease of total distances in open field test, and the prolonged duration of immobility in tail suspension test and forced swimming test. Treatment with CYT for two weeks notably relieved the depression-like behaviors in the UCMS mice. Next, proteins related to depressive disorder in the brain region of hippocampus and amygdala were analyzed to elucidate the underlying mechanisms of CYT. CYT significantly reversed the decreases of 5-HT1A, BDNF, and mTOR levels in the hippocampus and amygdala. These results imply that CYT may act as a potential anti-depressant in the animals under chronic stress.

Electrospun Fibrous Silk Fibroin/Poly(L-Lactic Acid) Scaffold for Cartilage Tissue Engineering

Weiwei Liu,Zhengqiang Li,Lu Zheng,Xiaoyan Zhang,Peng Liu,Ting Yang,Bing Han 한국조직공학과 재생의학회 2016 조직공학과 재생의학 Vol.13 No.5

For successful tissue engineering of articular cartilage, a scaffold with mechanical properties that match those of natural cartilage as closely as possible is needed. In the present study, we prepared a fibrous silk fibroin (SF)/poly(L-lactic acid) (PLLA) scaffold via electrospinning and investigated the morphological, mechanical, and degradation properties of the scaffolds fabricated using different electrospinning conditions, including collection distance, working voltage, and the SF:PLLA mass ratio. In addition, in vitro cell-scaffold interactions were evaluated in terms of chondrocyte adhesion to the scaffolds as well as the cytotoxicity and cytocompatibility of the scaffolds. The optimum electrospinning conditions for generating a fibrous SF/PLLA scaffold with the best surface morphology (ordered alignment and suitable diameter) and tensile strength (~1.5 MPa) were a collection distance of 20 cm, a working voltage of 15 kV, and a SF:PLLA mass ratio of S50P50. The degradation rate of the SF/PLLA scaffolds was found to be determined by the SF:PLLA mass ratio, and it could be increased by reducing the PLLA proportion. Furthermore, chondrocytes spread well on the fibrous SF/PLLA scaffolds and secreted extracellular matrix, indicating good adhesion to the scaffold. The cytotoxicity of SF/PLLA scaffold extract to chondrocytes over 24 and 48 h in culture was low, indicating that the SF/PLLA scaffolds are biocompatible. Chondrocytes grew well on the SF/PLLA scaffold after 1, 3, 5, and 7 days of direct contact, indicating the good cytocompatibility of the scaffold. These results demonstrate that the fibrous SF/PLLA scaffold represents a promising composite material for use in cartilage tissue engineering.

Compound glycyrrhizin injection for improving liver function in children with acute icteric hepatitis: A systematic review and meta-analysis

Liang Shi-Bing,Hou Wen-Bin,Zheng Ruo-Xiang,Liang Chang-Hao,Yan Li-Jiao,Wang Hao-Nan,Cao Hui-Juan,Han Mei,Robinson Nicola,Liu Jian-Ping 한국한의학연구원 2022 Integrative Medicine Research Vol.11 No.1

Background: Compound glycyrrhizin injection (CGI) is a preparation with glycyrrhizin as the main active ingredient extracted from licorice. As clinical trials suggest that CGI is effective in improving liver function for acute icteric hepatitis in children (AIHC), this systematic review aimed to evaluate and verify its therapeutic effects and safety. Methods: Six electronic databases were searched from their inception to 15 May 2021. Randomized controlled trials (RCTs) assessing therapeutic effects and safety of CGI for AIHC were included. The risk of bias for each trial was assessed using the Cochrane Risk of Bias Tool 2.0. Primary outcomes were indexes related to liver function, including total bilirubin (TBiL), alanine aminotransferase (ALT) and aspartate transaminase (AST). RevMan 5.4 software was used for data analyses. The certainty of the evidence was assessed using the online GRADEpro tool. Results: Six RCTs involving 608 children were included. The overall bias was assessed as having “high risk of bias” in all trials. All trials compared the combination of CGI and conventional western medicine (CWM) with CWM alone. Regarding the effects of CGI for AIHC, results showed that CGI plus CWM was superior to CWM alone in reducing the levels of TBiL (mean difference (MD) = -8.19 mmol/L, 95% CI -9.86 to -6.53), ALT (MD = -24.09 U/L, 95% CI -30.83 to -17.34) and AST (MD = -18.67 U/L, 95% CI -21.88 to -15.45). No trial reported adverse events. The certainty of the evidence for outcomes were all evaluated as low or very low. Conclusion: CGI may have adjuvant therapeutic effects on improving the liver function of children with AIHC. There is no evidence to determine the safety of CGI for AIHC. As current evidence is weak, further well-designed RCTs are required for verification of the therapeutic effects of CGI. Background: Compound glycyrrhizin injection (CGI) is a preparation with glycyrrhizin as the main active ingredient extracted from licorice. As clinical trials suggest that CGI is effective in improving liver function for acute icteric hepatitis in children (AIHC), this systematic review aimed to evaluate and verify its therapeutic effects and safety. Methods: Six electronic databases were searched from their inception to 15 May 2021. Randomized controlled trials (RCTs) assessing therapeutic effects and safety of CGI for AIHC were included. The risk of bias for each trial was assessed using the Cochrane Risk of Bias Tool 2.0. Primary outcomes were indexes related to liver function, including total bilirubin (TBiL), alanine aminotransferase (ALT) and aspartate transaminase (AST). RevMan 5.4 software was used for data analyses. The certainty of the evidence was assessed using the online GRADEpro tool. Results: Six RCTs involving 608 children were included. The overall bias was assessed as having “high risk of bias” in all trials. All trials compared the combination of CGI and conventional western medicine (CWM) with CWM alone. Regarding the effects of CGI for AIHC, results showed that CGI plus CWM was superior to CWM alone in reducing the levels of TBiL (mean difference (MD) = -8.19 mmol/L, 95% CI -9.86 to -6.53), ALT (MD = -24.09 U/L, 95% CI -30.83 to -17.34) and AST (MD = -18.67 U/L, 95% CI -21.88 to -15.45). No trial reported adverse events. The certainty of the evidence for outcomes were all evaluated as low or very low. Conclusion: CGI may have adjuvant therapeutic effects on improving the liver function of children with AIHC. There is no evidence to determine the safety of CGI for AIHC. As current evidence is weak, further well-designed RCTs are required for verification of the therapeutic effects of CGI.

ANALYZING ISUAL SPECTROPHOTOMETER DATA USING A TWO-COLOR DIAGRAM METHOD

CHEN ALFRED BING-CHIH,CHIANG PO-SHIH,HUANG TIAN-HSIANG,KUO CHENG-LING,WANG SHI-CHUN,SU HAN-TZONG,HSU RUE-RoN,CHANG MING-HUI,CHANG YEOU-SHIN,LIU TIE-YUE,MENDE STEPHEN B.,FREY HARALD U.,FUKUNISHI HIROSH The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.2

Transient luminous events (TLEs; sprites, elves, jets and etc.) are lightning-related optical flashes occurring above thunderstorms. Since the first discovery of sprites in 1989, scientists have learned a great deal about the morphological, spectroscopic and electromagnetic characteristics of TLEs through ground and spacecraft campaigns. However, most of the TLE studies were based on events recorded over US High Plains. To elucidate the possible biasing effects, space-borne observations are needed and have their merits. Imager of sprites and Upper Atmospheric Lightning (ISUAL) on the FORMOSAT-2 satellite is the first instrument to carry out a true global measurement of TLEs from a low- earth orbit. In this short paper, we apply a common astronomical data analysis technique, two-color diagram, on the ISUAL spectrophotometer (SP) data. By choosing appropriated bandpasses and converting the measured flux of TLEs into the unit of magnitude, two-color diagrams of TLEs can be constructed. We demonstrate that two-color diagrams, which were constructed from the narrow-band spectrophotometer data, can be used to classify different types of TLEs and trace their temporal evolution. The amount of reddening due to Earth's atmosphere can also be estimated from two-color diagrams assembled from the broad-band spectrophotometer data.