Terrestrial LiDAR-based bridge evaluation

Considering the over half million bridges in the US state highway system, more than 70% of which were built before 1935, it is of little wonder that bridge maintenance and management is facing severe challenges and the significant funding scarcity rapidly escalates the problem. Commercial remote sensing techniques have the capability of covering large areas and are suggested to be cost effective methods for bridge inspection. This dissertation introduces several applications of the remote bridge inspection technologies using ground-based LiDAR systems. In particular, the application of terrestrial LiDAR for bridge health monitoring is studied. An automatic bridge condition evaluation system based on terrestrial LiDAR data, LiBE (LiDAR-based Bridge Evaluation), is developed. The research works completed thus far have shown that LiDAR technology has the capability for bridge surface defect detection and quantification, clearance measurement, and displacement measurement during bridge static load testing. Several bridges in Mecklenburg County, NC, and other areas have been evaluated using LiBE and quantitative bridge rating mechanisms are proposed. A cost-benefit analysis has been conducted that demonstrates the relevancy of the technique to current nation-wide bridge management problem, as well as, the potential of reducing the bridge maintenance costs to the stack holders. The results generated from these technologies are valuable for bridge maintenance decision making

Crystal structure and biochemical analyses reveal Beclin 1 as a novel membrane binding protein

The Beclin 1 gene is a haplo-insufficient tumor suppressor and plays an essential role in autophagy. However, the molecular mechanism by which Beclin 1 functions remains largely unknown. Here we report the crystal structure of the evolutionarily conserved domain (ECD) of Beclin 1 at 1.6 Å resolution. Beclin 1 ECD exhibits a previously unreported fold, with three structural repeats arranged symmetrically around a central axis. Beclin 1 ECD defines a novel class of membrane-binding domain, with a strong preference for lipid membrane enriched with cardiolipin. The tip of a surface loop in Beclin 1 ECD, comprising three aromatic amino acids, acts as a hydrophobic finger to associate with lipid membrane, consequently resulting in the deformation of membrane and liposomes. Mutation of these aromatic residues rendered Beclin 1 unable to stably associate with lipid membrane in vitro and unable to fully rescue autophagy in Beclin 1-knockdown cells in vivo. These observations form an important framework for deciphering the biological functions of Beclin 1

The Relationship between Poisson’s Ratio Index and Deformation Behavior of Asphalt Mixtures Tested through an Optical Fiber Bragg Grating Strain Sensor

Flow-rutting is the main distress leading asphalt pavement to undergo premature maintenance, and is produced by the rapid accumulation of shear deformation in asphalt layers under high temperature and heavy loads. The excessive permanent deformation of the asphalt mixture at high temperature is related to the decrease of the material’s stability during the temperature increase and an unfavorable stress state, e.g., low confining pressure and high shear stress, which eventually leads to significant nonlinear viscoplastic behavior. In this research, dynamic modulus tests and repeated loading tests were carried out at 35 °C and 50 °C to analyze the deformation response of materials under a strain amplitude of <200 με and 400~500 μεs, respectively. Based on the in-lab repeated loading tests, the total deformation of the asphalt mixture in each loading and rest cycle was divided into three parts, being elastic, viscoelastic, and viscoplastic strain, and the measurement of the axial and lateral strain of cylindrical samples was realized with the aid of optical fiber Bragg grating strain sensors. It was found that the experimental index of the ratio between lateral strain and longitudinal strain (RLSLS), derived, but distinguished, from Poisson’s ratio defined limited in elastic strain, can characterize the deformation in viscoelastic and viscoplastic behaviors of the mixes. Furthermore, the indices of dynamic modulus, phase angle, complex Poisson’s ratio, stiffness, and creep rate of four types of mixes containing different volcanic ash fillers and asphalt binders at 35 °C and 50 °C were systematically analyzed by the jointed experiments of modified dynamic modulus tests and repeated loading tests, and their consistent trending to the RLSLS index was obtained

Identification and Evolution of a Natural Tetr Protein Based on Molecular Docking and Development of a Fluorescence Polari-Zation Assay for Multi-Detection of 10 Tetracyclines in Milk

In this study, the identity of our recently produced natural TetR protein was identified by using the LC-ESI-MS/MS technique, and its recognition mechanisms, including the binding pocket, contact amino acids, intermolecular forces, binding sites, binding energies, and affinities for 10 tetracycline drugs were studied. Then, it was evolved by site-mutagenesis of an amino acid to produce a mutant, and a fluorescence polarization assay was developed to detect the 10 drugs in milk. The sensitivities for the 10 drugs were improved with IC50 values decreasing from 30.8–80.1 ng/mL to 15.5–55.2 ng/mL, and the limits of detection were in the range of 0.4–1.5 ng/mL. Furthermore, it was found that the binding affinity for a drug was the critical factor determining its sensitivity, and the binding energy showed little influence. This is the first study reporting the recognition mechanisms of a natural TetR protein for tetracyclines and the development of a fluorescence polarization assay for the detection of tetracyclines residues in food samples

Cell-free synthetic biology for in vitro biosynthesis of pharmaceutical natural products

Natural products with significant biological activities continuously act as rich sources for drug discovery and development. To harness the potential of these valuable compounds, robust methods need to be developed for their rapid and sustainable production. Cell-free biosynthesis of pharmaceutical natural products by in vitro reconstruction of the entire biosynthetic pathways represents one such solution. In this review, we focus on in vitro biosynthesis of two important classes of natural products, polyketides (PKs) and nonribosomal peptides (NRPs). First, we summarize purified enzyme-based systems for the biosynthesis of PKs, NRPs, and PK/NRP hybrids. Then, we introduce the cell-free protein synthesis (CFPS)-based technology for natural product production. With that, we discuss challenges and opportunities of cell-free synthetic biology for in vitro biosynthesis of natural products. Keywords: Cell-free synthetic biology, Purified enzymes, Cell-free protein synthesis, Polyketides, Nonribosomal peptides, In vitro biosynthesis, Natural product

Aqueous Flow Batteries: Research and Development

Flow batteries (FBs) have become a central topic recently, due to their promising prospect of addressing the issues of the random and intermittent nature of renewable energy sources. However, the successful industrialization of current FB systems is still limited by their relatively low energy densities and high cost. Research and development into novel aqueous FB systems with high energy density, high safety, and low cost are accordingly urgently required. Some novel aqueous FB systems have been explored in recent years to overcome issues of traditional FBs and vanadium FBs, in particular. Further modifications have also been made to improve their performance. In this review, appealing novel aqueous FB systems, such as zinc- and quinone-based FB systems, are reviewed, in terms of the operating principles, advantages, drawbacks, corresponding performance, and subsequent modifications. Moreover, recent investigations and advancements, and prospective research directions for novel aqueous FB systems, are summarized. Therefore, this review will provide guidance and perspectives for developing new aqueous FB systems

Cell-Free Expression of a Therapeutic Protein Serratiopeptidase

Serratiopeptidase is a clinical therapeutic protein for the treatment of human diseases such as arthritis, bronchitis, and thrombosis. Yet production of this protein in a heterologous host (e.g., Escherichia coli) is difficult due to the issue of protein insolubility and the requirement of laborious refolding procedures. Cell-free protein synthesis (CFPS) systems, derived from crude cell extracts, are effective platforms for the expression of recombinant proteins in vitro. Here, we report a new method to produce serratiopeptidase by using an E. coli-based CFPS system. After rational selection of cell extracts and construction of expression vectors, soluble expression of serratiopeptidase was achieved and the enzyme activity could be readily tested in the cell-free reaction mixture. By further optimizing the key parameters, optimum conditions for the enzyme activity assay were obtained, including the pH value at 5, reaction temperature at 45 °C, substrate concentration at 10 mg/mL, and supplementing Ca2+ ions at 5 mM. Moreover, the CFPS mixture was freeze-dried and the activity of serratiopeptidase could be regenerated by hydration without losing activity. Overall, the CFPS system enabled soluble expression of serratiopeptidase with catalytic activity, providing a new and promising approach for this enzyme production. Our work extends the utility of the cell-free platform to produce therapeutic proteins with clinical applications

Effect of Geographical Conditions on Moss–Soil Crust Restoration on Cut Rock Slopes in a Mountainous Area in Western Sichuan, China

Ecological restoration has great significance on cut rock slopes, which are considered extremely degraded habitats. The development of moss–soil crusts on cut rock slopes as a critical pathway to ecological restoration in mountain areas has been poorly reported. A total of 335 quadrats were selected on cut rock slopes with formation ages between 0 and 60 years to evaluate the evolution characteristics of moss–soil crusts under various geographical conditions (e.g., aspect, lithology, and altitude) in the mountainous area of western Sichuan, Southwest China. The results suggested that moss growth decoupled from soil accumulation within the crusts and was controlled by multiple factors. Moss growth depended on lithology, altitude, and age, while soil weight was mainly influenced by slope aspect. The development of mosses on limestone was better than on sandstone. Moss biomass varied with altitude, consistent with that of rainfall with respect to moss development dependent on moisture. Furthermore, moss development under a semiarid climate was more distinctly impacted by moisture with altitude relative to a humid region, likely owing to the higher sensitivity of the mosses to moisture in the former than in the latter. Moss biomass increased with recovery time, while the rate of moss biomass development was diverse in different geographical areas. The vegetation developed rapidly in low-altitude areas (~1000 m above sea level), resulting in moss biomass increasing from 0 to 24.08 g·m−2 with formation time increasing from 0.5 to 1.5 years and subsequently being restricted by the evolution of higher plants on cut rock slopes, leading to an insignificant difference in moss biomass between 1.5 and 60 years. In high-altitude areas, when the altitude changed slightly (from 2024 to 2430 m above sea level), the moss biomass on cut rock slopes increased linearly with increasing age from 5 to 27 years. Influenced by the surrounding fertile soils and moss bioaccumulation, there were high levels of soil major nutrient content, especially the organic matter content, which reached 377.42 g·kg−1. More soils accumulated on south-facing slopes than on north-facing slopes. This study provided field data to clearly reveal the influence of geographic factors on moss–soil crust development in natural restoration processes in high-altitude mountainous areas

OFBG-Based Smart Double-Skin Tubular Confined-Concrete Column with Basalt FRP-Steel Composite

Fiber-reinforced polymer (FRP) composites have been widely employed to design advanced structural columns such as the hybrid FRP&ndash;concrete&ndash;steel double-skin tubular column (hybrid DSTC) with potential benefits. To date, the safety and self-monitoring of the hybrid DSTCs are still a challenge to overcome due to the complex damage scenarios. This paper investigates the self-sensing performance of a newly developed smart double-skin tubular confined concrete column (smart BFST-DSTC) made of basalt FRP&ndash;steel composite with built-in optical fiber Bragg grating sensors (OFBGs). The design of the smart BFST-DSTC and sensing principle are firstly addressed, followed by an experimental investigation on the basic mechanical properties and strain-based sensing performance of ten scaled specimens under axial compression. The outcomes reveal the enhancement of the proposed column in terms of load-carrying capacity, confinement ratio, and axial stress-axial strain behavior, as well as failure and damage modes when compared with the hybrid DSTC. The self-sensing investigation demonstrates that the measurement range satisfies the requirement to monitor and evaluate the hoop strains of the FRP jackets and the health state of the inner tube. The smart BFST-DSTC can replace the hybrid DSTC with the ability to provide early failure warning and life cycle health monitoring

Improving the electrochemical performance of Na3V2(PO4)(3) cathode in sodium ion batteries through Ce/V substitution based on rational design and synthesis optimization

Ce atom is employed to partially substitute V site in Na3V2(PO4)(3) (NVP) crystal structure to improve its bulk phase characteristic. The effect of Ce substitution on the crystal structure, morphology, electrochemical performance and kinetic property of NVP is investigated based on rational design and synthesis optimization. The results indicates that the moderate Ce substitution in the NVP crystal can effectively enhance the bulk phase electronic conductivity and Na+ mobility, which excludes the carbon coating effect for the first time. And Na3V1.96Ce0.04(PO4)(3)/C shows the best electrochemical performances among the Na3V2-xCex(PO4)(3)/C (x = 0, 0.02, 0.04, 0.06 and 0.1) samples. It delivers a discharge capacity of 118 mAh g(-1) at 0.2C and more than 100 mAh g(-1) even at 40C, which is currently the highest level by metallic ion doping. After 100 cycles, the capacity retention of Na3V1.96Ce0.04(PO4)(3)/C keeps higher than 99% at 10C. The outstanding performance of the moderate Ce-doping sample is verified further by the electrochemical performance test of the samples with high mass loading, which is highly beneficial to industrial applications of Na3V2(PO4)(3) cathode for high performance sodium ion batteries. (C) 2017 Elsevier Ltd. All rights reserved