One-Pot Enzymatic Synthesis of UDP-GlcA and UDP-GalA and Chemoenzymatic Synthesis of a Library of Human Milk Oligosaccharides and Enzymatic Synthsis of O-antigen from P. aeruginosa serotype O11

Carbohydrates are ubiquitous in nature and provide the function of protection and recognition in many biological systems. Therefore, the efficient synthesis of carbohydrate-based compounds is of considerable interest for both research and commercial purposes. However, unlike DNA and protein, successful synthesis of glycan is still challenging, due to the large number of sugar nucleotides and the several different linkage and conformation. Therefore, to tackle the challenge of glycosynthesis, chemists are increasingly turning their attention towards enzymes, which are exquisitely adapted to the intricacy of these biomolecules. In this dissertation, we will focus on practical biosynthesis of glycome such as UDP-GlcA and UDP-GalA, HMOcomics, O-Polysaccharides. Chapter 1 provides a general introduction of function of glycosylation of protein and glycan synthetic approaches. Chapter 2 describes that innovative approach of biosynthesis of UDP-GlcA and UDP-GalA by utilizing salvage pathway. UDP-HexA is active form of monosaccharide for further glycosylation which occurs in the biosynthesis of numerous cell components. Limited availability of these sugar nucleotides has been hindering the development of facile synthesis of bioactive glycans. In this study, we have developed an efficient and facile one-pot multi-enzyme method to harvest hundreds milligram of UDP-GlcA and UDP-GalA. In Chapter 3, Human milk sugar library synthesis is the footstone for future manufacturing specific human milk sugar macro array which can be used for screening blood and virus. A tremendous human milk sugar library is the foundation for application of macro-array in multiple research area. we accomplished a work of chemoenzymatic synthesize 31 HMOs based on 3 chemically synthesized core structures. A more comprehensive 100 HMOs library by 7 robust glycosyltransferases have been accomplished for printing array to screen virus and bacteria. In Chapter 4, chemoenzymatic synthesis of O-antigen from P. aeruginosa serotype O11 was achieved by two glycotransferases WbjE and WbjA. The bacterial cell surface is decorated with polysaccharides whose structures show remarkable diversity. These polysaccharides play critical role of interaction between Host and bacterium. Many are important virulence factors, adhesion mediators, or immunomodulators. Successful reconstitution of pure homogenous repeat unit of PS can facilitate development of multivalence bacterial vaccine

Magnetopause Reconnection as Influenced by the Dipole Tilt Under Southward IMF Conditions: Hybrid Simulation and MMS Observation

Using a three‐dimensional (3‐D) global‐scale hybrid code, the Magnetospheric Multiscale (MMS) reconnection event around 02:13 UT on 18 November 2015, highlighted in the Geospace Environment Modeling (GEM) Dayside Kinetic Challenge, is simulated, in which the interplanetary magnetic field (IMF) points southward and the geomagnetic field has a −27° dipole tilt angle. Strong southward plasma jets are found near the magnetopause as a result of the dayside reconnection. Our results indicate that the subsolar magnetopause reconnection X line shifts from the subsolar point toward the Northern Hemisphere due to the effect of the tilted geomagnetic dipole angle, consistent with the MMS observation. Subsequently, the reconnection X lines or sites and reconnection flux ropes above the equator propagate northward along the magnetopause. The formation and global distribution of the X lines and the structure of the magnetopause reconnection are investigated in detail with the simulation. Mirror mode waves are also found in the middle of the magnetosheath downstream of the quasi‐perpendicular shock where the plasma properties are consistent with the mirror instability condition. As a special outcome of the GEM challenge event, the spatial and temporal variations in reconnection, the electromagnetic power spectra, and the associated D‐shaped ion velocity distributions in the simulated reconnection event are compared with the MMS observation.Key PointsSubsolar magnetopause X lines shift toward the Northern Hemisphere due to the effect of the negative tilted geomagnetic dipole angleThe hybrid simulation magnetic fields and plasma date match MMS3 observations well during the magnetopause crossingMirror mode waves appear in the middle of the magnetosheath downstream of the quasi‐perpendicular shockPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/162687/2/jgra55909_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/162687/1/jgra55909.pd

Human in Events: A Large-Scale Benchmark for Human-centric Video Analysis in Complex Events

Along with the development of modern smart cities, human-centric video analysis has been encountering the challenge of analyzing diverse and complex events in real scenes. A complex event relates to dense crowds, anomalous, or collective behaviors. However, limited by the scale of existing video datasets, few human analysis approaches have reported their performance on such complex events. To this end, we present a new large-scale dataset, named Human-in-Events or HiEve (Human-centric video analysis in complex Events), for the understanding of human motions, poses, and actions in a variety of realistic events, especially in crowd and complex events. It contains a record number of poses (>1M), the largest number of action instances (>56k) under complex events, as well as one of the largest numbers of trajectories lasting for longer time (with an average trajectory length of >480 frames). Based on this dataset, we present an enhanced pose estimation baseline by utilizing the potential of action information to guide the learning of more powerful 2D pose features. We demonstrate that the proposed method is able to boost the performance of existing pose estimation pipelines on our HiEve dataset. Furthermore, we conduct extensive experiments to benchmark recent video analysis approaches together with our baseline methods, demonstrating that HiEve is a challenging dataset for human-centric video analysis. We expect that the dataset will advance the development of cutting-edge techniques in human-centric analysis and the understanding of complex events. The dataset is available at http://humaninevents.orgComment: Dataset for Large-scale Human-centric Video Analysis in Complex Events (http://humaninevents.org

Frequency-dependent orthotropic damping properties of Nomex honeycomb composites

In this paper, the orthotropic damping behavior of Nomex honeycomb composites and its causes are investigated. The needed specimen sizes for the measurement of the frequency-dependent transverse shear moduli (TSM) and fundamental damping coefficients of the honeycomb cores were analyzed at first. Then, the effects of cell side length and beam orientation on the orthotropic damping properties were explored. The results reveal that relatively high TSM (GLT) and damping values (ηWT) can be obtained by decreasing the cell side length without adding any additional weight. Damping mechanism analysis indicates that the difference in damping contribution of the interfacial phase to honeycomb core in different directions leads to the orthotropic damping behavior of honeycomb core. This study is helpful to guide the TSM measurement and structure design of honeycomb composites

Sensitivity Enhancement of a Self-Mixing Laser Diode Sensor by Using a Dual-cavity Configuration

When a part of light emitted by a laser is back-reflected or back- scattered from an external target and re-enters the laser cavity, the laser output power will be modulated. This is called Self-Mixing Effect (SME), which is a universal phenomenon occurring in lasers regardless of type. For SME based laser sensing system, a laser diode is usually employed to make a compact sensing system due to its small size. The laser diode in this case is also called Self-Mixing Laser Diode (SMLD). In some practical cases, a target surface has a very low reflectivity and thus not able to provide enough high feedback light to the laser diode. In this case, the observed sensing signal from the SMLD sensor is blurred and sensing sensitivity is degraded. To improve the sensing ability, we propose to apply a pre-feedback to the SMLD sensor. Investigation from both simulation and experiments are conducted to verify the proposed design. The results show that a proper pre-feedback can greatly enhance the sensing performance for a SMLD sensor

Preparation of TiO2/SiO2 composite fiber by thermal decomposition of polycarbosilane-tetrabutyl titanate hybrid precursor

National Natural Science Foundation of China [50532010]; Fujian Key Laboratory of Advanced Materials, China [2006L2003]A hybrid polymer as the precursor for TiO2/SiO2 composite fibers was prepared by blending polycarbosilane (PCS) and tetrabutyl titanate, named as PCST, which contains unreacted organic tetrabutyl titanate compound. The PCST was characterized by FT-IR, TGA and NMR (H-1, C-13 and Si-29). The results showed that the PCST could be described as a part dispersion of Ti(OC4H9)(4) groups in the PCS chain matrix. The TiO2/SiO2 composite fibers were manufactured by melt-spinning PCST, maturing and curing the resulting fibers in air, followed by a final pyrolysis at 1200 degrees C in air. Based on the XRD, EPMA, EDS, SEM and HRTEM measurements, the TiO2/SiO2 fibers were made up of anatase-TiO2 nanocrystallites with a mean size of similar to 10 nm and in the amorphous silica phase