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In the field of perovskite optoelectronics, developing hole-transporting materials (HTMs) on the spiro[fluorene-9,9′-xanthene] (SFX) platform is one of the current research focuses. The SFX inherits the merits of spirobifluorene in terms of the configuration and property, but it is more easily derivatized and regulated by virtue of its binary structure. In this work, we design and synthesize four isomeric SFX-based HTMs, namely m-SFX-mF, p-SFX-mF, m-SFX-oF, and p-SFX-oF, through varying the positions of fluorination on the peripheral aniline units and their substitutions on the SFX core, and the optoelectronic performance of the resulting HTMs is evaluated in both perovskite solar cells (PSCs) and light-emitting diodes (PeLEDs) by the vacuum thermal evaporating hole-transporting layers (HTLs). The HTM p-SFX-oF exhibits an improved power conversion efficiency of 15.21% in an inverted PSC using CH3NH3PbI3 as an absorber, benefiting from the deep HOMO level and good HTL/perovskite interface contact. Meanwhile, the HTM m-SFX-mF provides a maximum external quantum efficiency of 3.15% in CsPb(Br/Cl)3-based PeLEDs, which is attributed to its perched HOMO level and shrunken band-gap for facilitating charge carrier injection and then exciton combination. Through elucidating the synergistic position effect of fluorination on aniline units and their substitutions on the SFX core, this work lays the foundation for developing low-cost and efficient HTMs in the future. [ABSTRACT FROM AUTHOR]

In this work, a fluorescent complex [Zn(NTD)2(DTP)2(H2O)2]·(H2O)0.8 (Complex Zn), (H2NTD = 1,4-naphthalenedicarboxylic acid and DTP = 3,5-di(1,2,4-triazol-1-yl)pyridine) was synthesized. The fluorescent complex was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and thermogravimetric, elemental, infrared spectroscopy, and fluorescence analyses. In the fluorescence sensing tests, Complex Zn exhibited excellent fluorescence quenching efficiency towards Fe3+, MnO4−, Cr2O72−, nitrofurantoin, and imidacloprid in aqueous media. A mechanism investigation suggested that the fluorescence quenching caused by the quenchers toward the sensor was due to the inner filter effect and the fluorescence resonance energy transfer effect in the fluorescent sensing process. [ABSTRACT FROM AUTHOR]

The fusion of spatial data with blockchain technologies presents an innovative approach towards a decentralized, secure, and trustworthy framework for spatial information management. This integration brings spatial representation to the forefront of blockchain, opening avenues for various sectorial applications. However, challenges like slow processing times, restricted query capabilities, and consistency issues have been identified within the blockchain system. Addressing these challenges, we propose an optimized method for spatial queries by leveraging the high-performance capabilities of spatial databases. Unlike conventional off-chain query techniques, our approach synergistically combines hyperledger fabric with a specialized spatial database. This fusion facilitates distributed spatial queries within blockchain framework, incorporating spatial operation functionalities into smart contracts while preserving the distributed nature of nodes and spatial databases. Enhancing system security, we incorporate a dual-stage verification mechanism alongside a salt-hash storage strategy to counteract potential unauthorized alterations. Initial results validate the efficacy of our methodology in terms of performance and security. Building on this foundation, we introduce a rental transaction system that effectively merges spatial data with blockchain, demonstrating the feasibility and potential of integrating spatial information into the blockchain, especially in the realm of real estate. [ABSTRACT FROM AUTHOR]

Coordination polymers (CPs) are organo-inorganic porous materials consisting of metal ions or clusters and organic linkers. These compounds have attracted attention for use in the fluorescence detection of pollutants. Here, two Zn-based mixed-ligand-bearing CPs, [Zn2(DIN)2(HBTC2−)2] (CP-1) and [Zn(DIN)(HBTC2−)]·ACN·H2O (CP-2) (DIN = 1,4-di(imidazole-1-yl)naphthalene, H3BTC = 1,3,5-benzenetricarboxylic acid, and ACN = acetonitrile), were synthesized under solvothermal conditions. CP-1 and CP-2 were characterized by single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, and powder X-ray diffraction analysis. Solid-state fluorescence analysis revealed an emission peak at 350 nm upon excitation at 225 and 290 nm. Fluorescence sensing tests showed that CP-1 was highly efficient, sensitive, and selective for detecting Cr2O72− at 225 and 290 nm, whereas I− was only detected well at an excitation of 225 nm. CP-1 detected pesticides differently at excitation wavelengths of 225 and 290 nm; the highest quenching rates were for nitenpyram at 225 nm and imidacloprid at 290 nm. The quenching process may occur via the inner filter effect and fluorescence resonance energy transfer. [ABSTRACT FROM AUTHOR]

Biochar has shown great promise in producing low-cost low-carbon concrete for civil infrastructure applications. However, there is limited research comparing the use of pristine and contaminated biochar in concrete. This paper presents comprehensive laboratory experiments and three-dimensional nonlinear finite element analysis on the mechanical, economical, and environmental performance of reinforced concrete beams made using concrete blended with biochar generated from vetiver grass roots after the roots were used in an oil extraction process. Both pristine biochar and biochar that were used to treat wastewater through adsorbing heavy metals (100 mg/L of Pb, Cu, Cd, and Zn) were investigated. The biochar was used to replace up to 6% Portland cement in concrete. Laboratory experiments were conducted to characterize the workability, mechanical properties, shrinkage, and leaching potential of the concrete blended with biochar. The results showed that using biochar could increase the compressive strengths and reduce the shrinkage of concrete without causing a leaching problem. The results from finite element analysis of the reinforced concrete beams showed that the use of biochar was able to increase the flexural performance of the beams as well as their economic and environmental performance. This research will promote the development and structural applications of low-cost low-carbon concrete. [ABSTRACT FROM AUTHOR]

Fiber Bragg grating (FBG) sensors have been applied to assess strains, stresses, loads, corrosion, and temperature for structural health monitoring (SHM) of steel infrastructure, such as buildings, bridges, and pipelines. Since a single FBG sensor measures a particular parameter at a local spot, it is challenging to detect different types of anomalies and interactions of anomalies. This paper presents an approach to assess interactive anomalies caused by mechanical loading and corrosion on epoxy coated steel substrates using FBG sensors in real time. Experiments were performed by comparing the monitored center wavelength changes in the conditions with loading only, corrosion only, and simultaneous loading and corrosion. The theoretical and experimental results indicated that there were significant interactive influences between loading and corrosion for steel substrates. Loading accelerated the progress of corrosion for the epoxy coated steel substrate, especially when delamination in the epoxy coating was noticed. Through the real-time monitoring from the FBG sensors, the interactions between the anomalies induced by the loading and corrosion can be quantitatively evaluated through the corrosion depth and the loading contact length. These fundamental understandings of the interactions of different anomalies on steel structures can provide valuable information to engineers for better management of steel structures. [ABSTRACT FROM AUTHOR]

Curved pedestrian bridges are important urban infrastructure with the desired adaptability to the landscape constraints and with aesthetic benefits. Pedestrian bridges feature thin cross-sections, which provide sufficient load capacities but lead to low natural frequencies that make the bridges susceptible to vibration under pedestrian excitation. This study investigates the lateral vibration of a curved bridge with a small radius down to 20 m, proposes an approach to mitigate the lateral vibration of bridges with large curvatures using distributed multiple tuned mass dampers (MTMD), and conducts in-situ bridge tests to evaluate the vibration mitigation performance. The lateral vibration was investigated through in-situ tests and finite element analysis as well as the code requirements. The key parameters of the distributed MTMD system were improved by strategically selecting the mass ratio, bandwidth, center frequency ratio, and damper number. The results showed that the curved bridge was subjected to significant lateral vibration due to the coupling of torque and moment, and the recommended design parameters for the studied bridge were derived, i.e., the total mass ratio is 0.02, bandwidth is 0.15, center frequency ratio is 1.0, and damper number is 3. The proposed approach effectively improves the deployment of MTMD for lateral vibration control of the curved bridge. The field tests showed that the vibration was reduced by up to 82% by using the proposed approach. [ABSTRACT FROM AUTHOR]

Rapid strengthening is focused on recently to reduce the time for reinforcement process and decrease the losses. However, there are some limits for the existing reinforcement technologies to be used for rapid strengthening. The paper reports an experimental investigation on eccentric compressive behavior of reinforced concrete columns that are strengthened using steel mesh reinforced resin concrete (SMRC) for rapid strengthening. Four reinforced concrete columns with 180 mm × 250 mm test cross section and 1000 mm test height were fabricated and tested under large eccentric compressive load. Among the four columns, three columns were strengthened using SMRC with different numbers of steel mesh layers; the other column was not strengthened and was used as the control specimen. The effect of layer number of steel mesh on the failure mode, cracking load and load capacity of the columns were studied. Finite element analysis was carried out to evaluate the effects of the layer number of steel mesh, thickness of SMRC layer, and the load-holding level on the load capacity of the columns. Results show that the crack distribution of the strengthened columns was influenced by the layer number of steel mesh. The layer number was the dominant variable for the load capacity, rather than the thickness of the SMRC layer. With the increase of load-holding level, the load capacity of the strengthened column decreased following a bilinear trend. Some conclusions can be drawn that the reasonable reinforcement ratio of steel mesh is about 2%. Resin concrete is mainly used as bonding layer. The decreasing rate of the bearing capacity is higher at the high load-holding levels. [ABSTRACT FROM AUTHOR]

Monorail transportation systems are widely built in medium and small cities, as well as hilly cities, because of their excellent performance. A prestressed concrete track beam is a key load-carrying structural component and guideway subjected to repeated traffic load. The fatigue behavior of the prestressed concrete beam is critical for the safety of the transportation system. This paper presents the results of an experimental study on the fatigue behavior of a prestressed concrete beam in terms of stiffness degradation and strain change. The displacement and rotation of the beam of concrete and reinforcement were examined, respectively. A three-dimensional finite element model was established to help understand the development of the mechanical behavior. No crack was observed throughout the test. Both concrete and bars behaved in their linear-elastic stage throughout the test, and the bond between them performed well. [ABSTRACT FROM AUTHOR]

Studies on impact effects of trains on the railway bridge are important for ensuring the reliability of bridge and the safety of train operation. This paper presents an experimental study on the dynamic effects of moving trains on a long-span railway continuous beam bridge. The dynamic responses of the bridge under the moving trains were measured through in-situ testing and finite element analysis. The influences of the moving trains and track irregularity are considered. The investigated influencing factors include the weight and speed of the train and the irregularity of the track on the bridge. The results indicate that the train’s speed does not have obvious influence on the impact factor, while train’s weight and track irregularity have notable effects on the impact factor. But from the overall development law, with the increase of train speed, the impact factor increases. The impact factors obtained in this study are larger than the values provided by the China bridge design codes, which indicates that the bridge code underestimates the impact effect of the train on the bridge. The design value of the impact factor should be properly improved in the bridge design. [ABSTRACT FROM AUTHOR]

In this study, a dynamic response analysis procedure is proposed and applied to investigate the dynamic responses of a straddle-type concrete-filled steel tube tied arch bridge under train and truck loadings. A numerical model of the coupled monorail train–bridge system is established to investigate the dynamic behaviors of the bridge under moving trains. A refined three-dimensional finite element model is built for the bridge and a 15 degrees-of-freedom vehicle model is presented for the train. The numerical model is validated using in-situ test results and then used to analyze the dynamic displacement and acceleration of the bridge and the trains on the bridge. Based on the simulation results, the impact factor of the bridge is investigated and the riding comfort of the trains is evaluated. The investigation results show that the impact factor of vehicle loads reaches the maximum value when the resonance of the bridge is induced by the moving vehicles. The effect of train braking predominates the longitudinal vibration of the bridge but is negligible in the transverse and vertical directions. The vehicle speed is the dominating factor for the riding comfort of the train. [ABSTRACT FROM AUTHOR]

Current development of high-performance fiber-reinforced cementitious composites (HPFRCC) mainly relies on intensive experiments. The main purpose of this study is to develop a machine learning method for effective and efficient discovery and development of HPFRCC. Specifically, this research develops machine learning models to predict the mechanical properties of HPFRCC through innovative incorporation of micromechanics, aiming to increase the prediction accuracy and generalization performance by enriching and improving the datasets through data cleaning, principal component analysis (PCA), and K-fold cross-validation. This study considers a total of 14 different mix design variables and predicts the ductility of HPFRCC for the first time, in addition to the compressive and tensile strengths. Different types of machine learning methods are investigated and compared, including artificial neural network (ANN), support vector regression (SVR), classification and regression tree (CART), and extreme gradient boosting tree (XGBoost). The results show that the developed machine learning models can reasonably predict the concerned mechanical properties and can be applied to perform parametric studies for the effects of different mix design variables on the mechanical properties. This study is expected to greatly promote efficient discovery and development of HPFRCC. [ABSTRACT FROM AUTHOR]

In cement composites, usually, reinforcement is provided to restrict the crack development and their further propagation under service conditions. Typically, reinforcements utilized in cementitious composites range from nanometer scale to millimeter scale by using nano-, micro-, and millimeter-sized fibers and particles. These reinforcements provide the crack arresting mechanisms at the nano/microscale and restrict the growth of the cracks under service loads, but usually, the synthesis of nano/microfibers, and afterward their dispersion in the cementitious materials, pose difficulty, thus limiting their vast application in the construction industry. Carbonaceous inerts are green materials since they are capable of capturing and storing carbon, thus limiting the emission of CO2 to the atmosphere. In the present study, a comprehensive review of the synthesis of low cost and environmentally friendly nano/micro carbonaceous inerts from pyrolysis of different agricultural/industrial wastes, and afterward, their application in the cementitious materials for producing high performance cementitious composites is presented, which have the potential to be used as nano/micro reinforcement in the cementitious matrix. [ABSTRACT FROM AUTHOR]

In the last few decades, the demand for cement production increased and caused a massive ecological issue by emitting 8% of the global CO2, as the making of 1 ton of ordinary Portland cement (OPC) emits almost a single ton of CO2. Significant air pollution and damage to human health are associated with the construction and cement industries. Consequently, environmentalists and governments have ordered to strongly control emission rates by using other ecofriendly supplemental cementing materials. Rice husk is a cultivated by-product material, obtained from the rice plant in enormous quantities. With no beneficial use, it is an organic waste material that causes dumping issues. Rice husk has a high silica content that makes it appropriate for use in OPC; burning it generates a high pozzolanic reactive rice husk ash (RHA) for renewable cement-based recyclable material. Using cost-effective and commonly obtainable RHA as mineral fillers in concrete brings plentiful advantages to the technical characteristics of concrete and to ensure a clean environment. With RHA, concrete composites that are robust, highly resistant to aggressive environments, sustainable and economically feasible can be produced. However, the production of sustainable and greener concrete composites also has become a key concern in the construction industries internationally. This article reviews the source, clean production, pozzolanic activity and chemical composition of RHA. This literature review also provides critical reviews on the properties, hardening conditions and behaviors of RHA-based concrete composites, in addition to summarizing the research recent findings, to ultimately produce complete insights into the possible applications of RHA as raw building materials for producing greener concrete composites—all towards industrializing ecofriendly buildings. [ABSTRACT FROM AUTHOR]

Detailed information about temperature distribution can be important to understand structural behavior in fire. This study develops a method to image three-dimensional temperature distributions in steel–concrete composite slabs using distributed fiber optic sensors. The feasibility of the method is explored using six 1.2 m × 0.9 m steel–concrete composite slabs instrumented with distributed sensors and thermocouples subjected to fire for over 3 h. Dense point clouds of temperature in the slabs were measured using the distributed sensors. The results show that the distributed sensors operated at material temperatures up to 960 °C with acceptable accuracy for many structural fire applications. The measured non-uniform temperature distributions indicate a spatially distributed thermal response in steel–concrete composite slabs, which can only be adequately captured using approaches that provide a high density of through-depth data points. [ABSTRACT FROM AUTHOR]

A three-dimensional bay-annulated-indigo (BAI) tetramer has been prepared by appending BAI units onto a low-cost spiro[fluorene-9,9′-xanthene] (SFX) core. The target compound 4BAI-SFX exhibits strong and broad absorption in the visible region covering the range of 450~700 nm. The electrochemical measurement illuminates the characteristics of a deep lowest unoccupied molecular orbital (LUMO) level and multiple redox states of 4BAI-SFX. These results suggest that 4BAI-SFX should be a selectable electron-transporting material for eco-friendly organic semiconductors. [ABSTRACT FROM AUTHOR]

Reliable and accurate measurements of temperature and strain in structures subjected to fire can be difficult to obtain using traditional sensing technologies based on electrical signals. Fiber optic sensors, which are based on light signals, solve many of the problems of monitoring structures in high temperature environments; however, they present their own challenges. This paper, which is intended for structural engineers new to fiber optic sensors, reviews various fiber optic sensors that have been used to make measurements in structure fires, including the sensing principles, fabrication, key characteristics, and recently-reported applications. Three categories of fiber optic sensors are reviewed: Grating-based sensors, interferometer sensors, and distributed sensors. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of distributed fiber optic sensor for corrosion monitoring of steel bars embedded in concrete. Two sensor installation methods are compared: (1) attaching the sensor along the bar and (2) winding the sensor on the bar. For the second method, optical fibers were winded spirally on steel bars with different spacings: 0 mm, 2 mm, 5 mm, and 10 mm. Steel bar pull-out testing was conducted to evaluate the effect of presence of distributed sensor on the bond strength of steel–concrete interface. Electrochemical testing was carried out to assess the influence of the installation methods on the corrosion resistance of the reinforced concrete. Winding the optical fiber on steel bars with a 10-mm spacing does not affect the bond strength and corrosion resistance and allows real-time corrosion monitoring. The distributed sensor data can be used to estimate the corrosion induced steel loss and predict concrete cracking. [ABSTRACT FROM AUTHOR]

The ATP-binding cassette transporter A1 (ABCA1) mediates the cellular efflux of excess cholesterol and phospholipids to lipid-poor apolipoprotein A-I (apoA-I). ABCA1 plays an important role in high-density lipoprotein (HDL) biogenesis and reverse cholesterol transport. By using a cell-based screening model for the ABCA1 up-regulator and column chromatography, an active compound, 9179B, was isolated. Through analysis of its NMR data, 9179B was identified as dehydroxytrichostatin A. We found that 9179B increased the transcription of ABCA1 in a cell-based reporter assay, with an EC(50) value of 2.65 μM. 9179B up-regulated ABCA1 expression at both mRNA and protein levels in HepG2 and RAW264.7 cells. It also up-regulated the expression of scavenger receptor class B type I (SR-BI) as well as the uptake of DiI-HDL in RAW264.7 cells. This compound stimulated ApoA-I-mediated cellular cholesterol efflux from RAW 264.7 cells. We further found that 9179B was a potent histone deacetylase (HDAC) inhibitor with an IC(50) value of 0.08 μM. Reporter gene assays showed that the regulation of ABCA1 transcription by 9179B was mainly mediated by the -171/-75 bp promoter region. Together, our results indicate that 9179B is an ABCA1 up-regulator and dehydroxytrichostatin A may be a novel anti-atherogenic compound.