Ballast Mechanical Performance with and without Under Sleeper Pads

Yunlong Guo,Jianxi Wang,Valeri Markine,Guoqing Jing 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.11

With the train speed and axle load increasing, excessive stresses are produced and transmitted to the ballast layer, inducing rapid ballast degradation. To solve this issue, the under sleeper pads (USPs) have been widely applied between sleepers and ballast particles as the elastic layer. In this research, laboratory tests using half-sleeper track were carried out to study the ballast bed performance with or without the USPs under static and cyclic loading. Results show that applying the USPs reduces the track stiffness and can decrease the settlement. However, installing the USPs increases the ballast bed acceleration and the sleeper vertical acceleration. The contact areas of sleeper-ballast with USPs are over 5 times as those without USPs. The USPs assist reducing ballast degradation mainly by avoiding the ballast particle breakage at the sleeper-ballast interface and can increase the stress distribution at the longitudinal direction.

Structural safety reliability of concrete buildings of HTR-PM in accidental double-ended break of hot gas ducts

Guo, Quanquan,Wang, Shaoxu,Chen, Shenggang,Sun, Yunlong Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.5

Safety analysis of nuclear power plant (NPP) especially in accident conditions is a basic and necessary issue for applications and commercialization of reactors. Many previous researches and development works have been conducted. However, most achievements focused on the safety reliability of primary pressure system vessels. Few literatures studied the structural safety of huge concrete structures surrounding primary pressure system, especially for the fourth generation NPP which allows existing of through cracks. In this paper, structural safety reliability of concrete structures of HTR-PM in accidental double-ended break of hot gas ducts was studied by Exceedance Probability Method. It was calculated by Monte Carlo approaches applying numerical simulations by Abaqus. Damage parameters were proposed and used to define the property of concrete, which can perfectly describe the crack state of concrete structures. Calculation results indicated that functional failure determined by deterministic safety analysis was decided by the crack resistance capability of containment buildings, whereas the bearing capacity of concrete structures possess a high safety margin. The failure probability of concrete structures during an accident of double-ended break of hot gas ducts will be 31.18%. Adding the consideration the contingency occurrence probability of the accident, probability of functional failure is sufficiently low.

Cloning and expression of a Chk1 gene in Daphnia pulex during different modes of reproduction

Xiaoge Guo,Shanliang Xu,Xuemei Yan,Wei Zhou,Xinyu Dai,Xiu Zou,Chunlin Wang,Danli Wang,Yunlong Zhao 한국유전학회 2015 Genes & Genomics Vol.37 No.9

The full-length cDNA of a Chk1 gene (DpChk1) was cloned from Daphnia pulex using RACE method. This cDNA is 1767 bp in length, consisting of a 1497 bp open reading frame encoding 498 amino acid protein. The deduced DpChk1 protein sequence contains phosphorylation sites, three conserved Ser-Gln and Thr- Gln motifs and shares 51–55 % similarity with A. pisum, M. rotundata, D. melanogaster, A. echinatior, B. terrestris, R. pulchellus and M. occidentalis, respectively. Gene expression analysis showed that Chk1 is differentially expressed in D. pulex during different reproductive modes. DpChk1 expression in sexually-reproducing females and males is significantly higher than in parthenogenetic Daphnia. Whole-mount in situ hybridization revealed that DpChk1 was expressed during two kinds of reproductive modes. In parthenogenetic females, hybridization signals were found in the antennae and thoracic limb, whereas expression levels in the corresponding sites of sexuallyreproducing females were relatively strong, DpChk1 could not be detected in the gonads of ephippial and parthenogenetic females. Taken together, these different reproductive stages and sex specific expression patterns are regulated temporally and spatially. We speculate that DpChk1 may be involved in conversion between different stages of reproduction and in sexual differentiation in D. pulex.

Experimental study on shear performance of partially precast Castellated Steel Reinforced Concrete (CPSRC) beams

Yong Yang,Yunlong Yu,Yuxiang Guo,Charles W. Roeder,Yicong Xue,Yongjian Shao 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2

A new kind of partially precast or prefabricated castellated steel reinforced concrete beam, which is abbreviated here as CPSRC beam, was presented and introduced in this paper. This kind of CPSRC beam is composed of a precast outer-part and a cast-in-place inner-part. The precast outer-part is composed of an encased castellated steel shape, reinforcement bars and high performance concrete. The cast-in-place inner-part is made of common strength concrete, and is casted with the floor slabs simultaneously. In order to investigate the shear performance of the CPSRC beam, experiments of six CPSRC T-beam specimens, together with experiments of one cast-in-place SRC control T-beam specimen were conducted. All the specimens were subjected to sagging bending moment (or positive moment). In the tests, the influence of casting different strength of concrete in the cross section on the shear performance of the PPSRC beam was firstly emphasized, and the effect of the shear span-to-depth ratio on that were also especially taken into account too. During the tests, the shear force-deflection curves were recorded, while the strains of concrete, the steel shapes as well as the reinforcement stirrups at the shear zone of the specimens were also measured, and the crack propagation pattern together with the failure pattern was as well observed in detail. Based on the test results, the shear failure mechanism was clearly revealed, and the effect of the concrete strength and shear span-to-depth ratios were investigated. The shear capacity of such kind of CPSRC was furthermore discussed, and the influences of the holes on the steel shape on the shear performance were particularly analyzed.

Understanding and controlling gold nanoparticle formation from a robust self-assembled cyclodextrin solid template

Chung, Jae Woo,Guo, Yunlong,Kwak, Seung-Yeop,Priestley, Rodney D. The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.13

<P>Recently, we discovered that cyclodextrin (CD)-stabilized gold nanoparticles could be synthesized in an aqueous medium from a self-assembled supramolecular structure of CD and gold salt. We showed that the self-assembled structure of the CD complex induced by the gold salt acted as a solid template for the formation of nanoconfined gold seeds and that gold seeds grew into CD-stabilized gold nanoparticles in water without the necessity of other reducing or stabilizing agents. Here, we extensively investigate the supramolecular self-assembled structure of the CD/gold salt complex under various synthetic conditions, the mechanism of the <I>α</I>-CD-stabilized gold nanoparticles formation, and the processing parameters for controlling the size of gold nanoparticles. We demonstrate that gold salts were confined between two different crystalline phases of the supramolecular CD solid template <I>via</I> a gold salt-induced molecular self-assembly process and that thermal treatment of the CD/gold salt complex led to the formation of nanosized gold seeds geometrically confined within the crystalline interface region. Placement of the thermally treated complex in water without the addition of any supplementary additives proliferated the growth of CD-stabilized gold nanoparticles <I>via</I> stabilization of the growing gold seed intermediates by CD molecules. In addition, various processing parameters such as Au salt concentration are shown to affect the size of AuNPs.</P> <P>Graphic Abstract</P><P>We investigate a synthetic procedure for the formation of size-variant colloidal gold nanoparticles (AuNPs) derived from the supramolecular self-assembled structure of a natural cyclodextrin (CD)/Au salt complex (CAT) without the necessity for additional reducing or stabilizing agents. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm16118d'> </P>

Analysis of oligosaccharides from Panax ginseng by using solid-phase permethylation method combined with ultra-high-performance liquid chromatography-Q-Orbitrap/mass spectrometry

Li, Lele,Ma, Li,Guo, Yunlong,Liu, Wenlong,Wang, Yang,Liu, Shuying The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.6

Background: The reports about valuable oligosaccharides in ginseng are quite limited. There is an urgent need to develop a practical procedure to detect and analyze ginseng oligosaccharides. Methods: The oligosaccharide extracts from ginseng were permethylated by solid-phase methylation method and then were analyzed by ultra-high-performance liquid chromatography-Q-Orbitrap/MS. The sequence, linkage, and configuration information of oligosaccharides were determined by using accurate m/z value and tandem mass information. Several standard references were used to further confirm the identification. The oligosaccharide composition in white ginseng and red ginseng was compared using a multivariate statistical analysis method. Results: The nonreducing oligosaccharide erlose among 12 oligosaccharides identified was reported for the first time in ginseng. In the comparison of the oligosaccharide extracts from white ginseng and red ginseng, a clear separation was observed in the partial least squares-discriminate analysis score plot, indicating the sugar differences in these two kinds of ginseng samples. The glycans with variable importance in the projection value large than 1.0 were considered to contribute most to the classification. The contents of oligosaccharides in red ginseng were lower than those in white ginseng, and the contents of maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose, maltooctaose, maltononaose, sucrose, and erlose decreased significantly (p < 0.05) in red ginseng. Conclusion: A solid-phase methylation method combined with liquid chromatography-tandem mass spectrometry was successfully applied to analyze the oligosaccharides in ginseng extracts, which provides the possibility for holistic evaluation of ginseng oligosaccharides. The comparison of oligosaccharide composition of white ginseng and red ginseng could help understand the differences in pharmacological activities between these two kinds of ginseng samples from the perspective of glycans.

Colloidal gold nanoparticle formation derived from self-assembled supramolecular structure of cyclodextrin/Au salt complex

Chung, Jae Woo,Guo, Yunlong,Priestley, Rodney D.,Kwak, Seung-Yeop Royal Society of Chemistry 2011 Nanoscale Vol.3 No.4

<P>We present a novel procedure for the formation of colloidal gold nanoparticles (<I>AuNPs</I>) derived from the supramolecular self-assembled structure of a cyclodextrin (<I>CD</I>)/Au salt complex (<I>SCA</I>) without the necessity for additional reducing or stabilizing agents. The <I>SCA</I> served as a solid template for the formation of gold seeds by <I>solid-state</I> thermal treatment within the confining environment of the <I>α-CD</I>, <I>i.e.</I>, the matrix of the <I>SCA</I>. Subsequently, thermally treated <I>SCA</I>, denoted as <I>T-SCA</I>, was placed (without further treatment) into an aqueous medium and gold seeds were nucleated for the formation of <I>α</I>-<I>CD</I>-stabilized <I>AuNPs</I> at room temperature. The surface topology of <I>SCA</I>, as revealed by field-emission scanning electron microscopy (FE-SEM), consisted of flaky plate-like structures. Wide angle X-ray diffraction (WXRD) revealed that the surface topology of <I>SCA</I> resulted from a transformation in the crystalline structure of <I>α-CD</I> from the cage-type to the hexagonally ordered channel-type. The structure transformation on the surface of <I>SCA</I> was attributed to the nucleated self-assembly of surface <I>α-CD</I> molecules by Au salt. From combined FE-SEM, energy-dispersed X-ray spectroscopy (EDXS), WXRD and differential scanning calorimetry (DSC) results, it was concluded that the thermal treatment of <I>SCA</I> led to the formation of gold seeds, attributed to the reduction and aggregation of some Au salt molecules, confined within the interface between the cage-type and channel type structure of the <I>SCA</I>. After placement of <I>T-SCA</I> into an aqueous solution, the growth and stabilization of <I>AuNPs</I> by <I>α-CD</I> were verified by UV-vis spectroscopy. The formation of <I>AuNPs</I>, by this novel method, can be considered a one step seed-mediated growth process. The resulting <I>AuNPs</I> are spherical in morphology, narrowly size distributed and possesses excellent stability. Furthermore, the <I>AuNPs</I> size is tunable by simply controlling water content during nanoparticle growth.</P> <P>Graphic Abstract</P><P>We present a novel procedure for the formation of size-variant colloidal gold nanoparticles (<I>AuNPs</I>) derived from the supramolecular self-assembled structure of a cyclodextrin (<I>CD</I>)/Au salt complex (<I>SCA</I>) without the necessity for additional reducing or stabilizing agents. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0nr00894j'> </P>

FLOURY ENDOSPERM12 Encoding Alanine Aminotransferase 1 Regulates Carbon and Nitrogen Metabolism in Rice

Mingsheng Zhong,Xi Liu,Feng Liu,Yulong Ren,Yunlong Wang,Jianping Zhu,Xuan Teng,Erchao Duan,Fan Wang,Huan Zhang,Mingming Wu,Yuanyuan Hao,Xiaopin Zhu,Ruonan Jing,Xiuping Guo,Ling Jiang,Yihua Wang,Jianmi 한국식물학회 2019 Journal of Plant Biology Vol.62 No.1

Starch is a major storage substance in cerealgrains, and starch biosynthesis is a complex process. In orderto elucidate regulation of the starch biosynthesis pathway, wescreened a series of rice (Oryza sativa L.) endospermmutants. In this study, we identified a floury white-coreendosperm mutant named floury endosperm12 (flo12). Theflo12 mutant exhibited loosely packed starch granules and alower thousand kernel weight compared to wild type. Semithinsections revealed that compound starch grains (SG) inflo12 interior endosperm cells were developed abnormally. Furthermore, amylose content was decreased, while totalprotein content was significantly increased in flo12 grains. Map-based cloning showed that FLO12 encodes rice alanineaminotransferase 1 (OsAlaAT1). OsAlaAT1 is highly expressedin developing endosperm. Subcellular localization showedthat OsAlaAT1 is localized in the cytosol. Moreover, theexpression of most starch synthesis-related genes wasdecreased, while most of the storage protein coding geneshad elevated expression levels in the flo12 mutant. Inaddition, overexpression of the OsAlaAT1 gene increasedgrain weight. In brief, we demonstrated that OsAlaAT1regulates carbon and nitrogen metabolism, which provides anew insight for the improvement of rice quality and yield.