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We study numerically the effects of free surface on a flapping-foil based ocean current energy extractor. A two-dimensional NACA0015 foil, subjected to a coupled pitching and heaving motions, at a fixed Reynolds number of 900, and varied Froude numbers between 0 and 2, is considered. We fix the non-dimensional frequency at f∗ = 0.16 and pitching amplitude at θ0 = 75°. The previous studies suggested that an energy extracting efficiency up to 0.30 could be achieved in a single-phase fluid flow at these specific parameters. In the current study, as the free surface is considered, we report that both the submergence depth and Froude number affect the energy extracting efficiency. As the submergence depth increases from H = 1 to H = 20, for all the Froude numbers considered, the efficiency converges eventually to 33.7%, though slightly higher efficiencies can be observed when both the depth and Froude number are small. At a fixed submergence depth, the efficiency decreases monotonically with the increasing Froude number, which trend is more pronounced when the depth is small, i.e., the foil is very close to the free surface. It is apparently suggested that the free surface plays an unfavorable role in the energy harvesting efficiency, therefore the foil should be deployed with a sufficiently large distance from the free surface, particularly when it operates at high Froude numbers.

The rapid development of the labor division system of the global value chain not only improves the technological level of developing countries but also creates opportunities for developed countries that dominate the global value chain to transfer pollution-intensive production links to developing countries. When faced with the pressure of environmental governance, the production efficiency of enterprises in the value chain may change significantly. Therefore, this study establishes a global value chain analysis framework, considering environmental factors, that is, the global environmental value chain (GEVC). It discusses the impact of the embeddedness of enterprises in the GEVC on their production efficiencies. Based on the consolidated data from 2000 to 2006 in the China Industry Business Performance Data and the China customs database, the following conclusion is drawn: The embeddedness of enterprises in the GEVC reduces the production efficiency of enterprises, but the changes of production efficiencies of enterprises with different profitability in the GEVC are significantly different. Specifically, the embeddedness of enterprises with positive earnings in the GEVC can improve production efficiency, while that of enterprises with negative earnings in the GEVC will reduce production efficiency. Furthermore, the learning effect and the competition effect reinforce the positive effect of GEVC on enterprise production efficiency, while the "capture effect" weakens this effect, and the scale effect is insignificant. Moreover, foreign-funded enterprises benefit more from the improvement of production efficiency that resulted from GEVC embeddedness.

Cemented Paste Backfill (CPB) technology has been effective in using the tailings to refill the underground cavities. The wet or dry rock surface can significantly affect the stability of the CPB-Rock interface, and the shear load-bearing capacity of CPB-Rock interface always reflects the overall stability of the filled underground cavities. Therefore, clear understanding on the shear behavior of the CPB-Rock interface with wet or dry rock surface is very important. To investigate the shear behavior of CPB-Rock interface with different rock surfaces (wet and dry), an apparatus for shear tests at CPB-Rock interface was constructed by modifying the servo-controlled GCTS (Geotechnical Consulting & Testing System) loading frame. Over 72 CPB-Rock samples with dry and wet rock surfaces were tested under four confining pressures (0, 50, 100 and 150 kPa) and different curing time (1, 3, 7 days). The findings show that, under the same confining pressure and curing time, the shear strength of the CPB-Rock interface with the dry rock surface is much larger than that of the wet one. Furthermore, with the increase of the curing time under a same confining pressure, the increase of shear strength on the dry rock surface is also larger than that of the wet one due to the presence of water film on the wet rock surface. The shear strength is enhanced with the increase of confining pressure. Further, the testing results were analyzed within the framework of the Mohr-Coulomb criterion, which comply with the corresponding theoretical curve. It is concluded that the dry rock surface is essential to the stability of the filled underground cavities. In case of wet environment for the underground cavities, it is important to find ways to dry the rock surface before carrying out back filling using CPB method.

The monsoon system modulates surface production in the South China Sea (SCS). The winter monsoon has long been recognized as the primary factor regulating surface production in the northern SCS; however, the role of monsoon remains in debate in the southern SCS. Here, we present a long record of short-chain n-fatty acids (n-FAs) in reefal carbonates from one deep well (NK1) on an isolated coral atoll (Meiji) in order to provide new insights into the change of surface production in the southern SCS since the Late Miocene (ca. 10.5 Ma). Short-chain n-FAs indicative of total marine organic matter input are rather feasible to reflect the total production associated with mixotrophic reef-building corals that feed on various marine biotas (i.e., phytoplankton, zooplankton and bacteria). By ruling out the significant influence of diagenetic and degradation processes, short-chain n-FAs can be further applied to reconstruct paleo-production in Well NK1 coral reefs. The temporal distribution of short-chain n-FAs changes similarly with many other independent paleo-production records (i.e., Ln(Ba/Ti) and opal) in Well NK1 and adjacent ODP Site 1143, demonstrating the close coupling between coral reef production and surface water production. This occurs through the common factor of nutrients in modulating production of symbiotic autotrophic coralgae and asymbiotic phytoplankton and/or the large heterotrophic dependence of corals on phytoplankton-governed food webs in surface waters. Short-chain n-FAs inferred surface production displays a progressively decreased trend from the Late Miocene to Pliocene (ca. 10.5–2.6 Ma) followed by a substantial increase since the Pleistocene on million-year timescales, which follows the variation of terrigenous supply to the coral atoll and responds almost inversely to the sea-level change. Accordingly, we propose that long-term paleo-production in the southern SCS was associated with terrestrial nutrient input which was controlled by relative sea-level change since the Late Miocene. This study highlights the feasibility of short-chain n-FAs as appropriate production recorders in shallow-water coral reefs which are widespread in tropical-subtropical oceans, providing valuable perspectives on long-term paleo-production evolution in surface waters.

The Suzuki coupling reaction was used to synthesize the poly (9,9-dioctylfluorene-2,7-diyl) (PFO), MWCNTs were doped in PFO by physical blending. Memristors were prepared with PFO and PFO:MWCNTs as active layer, and the effect of MWCNTs content on the electrical characteristics of the device was proved. The results reveal that the devices with doped and undoped MWCNTs had bistable nonvolatile memory behavior. After doping MWCNTs, the ON/OFF state current ratio is obviously improved and the device with 1.6% MWCNTs content shows the maximum ON/OFF curent ratio of 2.6 × 103 and lower threshold voltage approximately −0.7 V. Futhermore, the device remains stable for 3 h and the curent has no obvious change after 9000 read cycles, whether it is ON state or OFF state.

The dependence of human beings on natural resources is long-standing, and land resource is a crucial part of these natural resources. In recent years, land pollution and resource shortage have severely affected the normal lives of individuals. There is a growing appreciation of the need for studying the green supply chain of land. In this study, the land green supply chain is divided into subsystems of technology (T), energy (E), environment (E), and economy (E), which construct TEEE dynamic model. Based on the model, we simulate the develop trend of technology, energy, environment, and economy in Shandong Province from 2003 to 2020. Moreover, we find out optimal polices to realize economic and environmental objectives of 2020 of Shandong Province, and get the optimization scheme for environmental policy as below: water quota for farmland irrigation is 2780 m2 per hectare, quota for urban water consumption is 33 m3 per capita per year, quota for industrial water consumption is 8 m3 per CNY10000 and unqualified rate of industrial waste water is 1%. If regulating and controlling as per such objectives, total industrial population will be reduced to 99.87 million, total industrial output value will reach CNY 44.68 trillion and environmental pollution degree will get down to 1.153.

With the growth of international trade, the geographical separation of production and consumption links of goods has become increasingly common. Commodity-consuming countries can transfer carbon emissions generated in the production of commodities to commodity-producing countries through foreign trade while meeting their domestic consumption demands and emission reduction targets. This issue of embodied carbon emissions in international trade has received wide attention in recent years and has exerted significant impact on the labor income share of developing nations. This study determines the relationship between carbon emission and labor income share in the imports and exports of intermediate products from the perspective of the global value chain. Empirical results show that in developing countries, labor income share has a negative relationship with trade and a positive one with embodied carbon emission. Furthermore, to distinguish the heterogeneity between industries and verify the hypothesis, we classified 57 sectors into 7 main industries based on the method of Meng et al. (2018). Specifically, labor-intensive exports and technology-intensive imports increase labor income share while technology-intensive exports and labor-intensive imports reduce it. In addition to the light industry, the upgrading of women's employment structure can promote the increase of labor income share in host countries. The policy relevance of this study rests on its findings that developing countries can increase their labor income share through imports related to technology-intensive industries and exports related to labor-intensive industries; and that countries worldwide can fundamentally reduce embodied carbon emissions in trade by means of innovations in science and technology to realize sustainable development of the environment, economy, and society.

Novel ternary carbon quantum dots (CDs)/Bi2MoO6 (BMO)/graphitic carbon nanofibers (GNFs) composites (CDs/BMO/GNFs) were prepared by a facile hydrothermal method and studied for use as photocatalysts. The morphological, structural and physicochemical properties of the as-prepared photocatalysts were examined in detail; that the CDs-decorated BMO particles anchored on the surfaces of modified GNFs to form heterojunctions. The photocatalytic activity of the resultant CDs/BMO/GNFs was superior for the degradation of three different organics, including Rhodamine B (RhB), methylene blue (MB) and phenol, as well as the reduction of a heavy metal ion Cr(VI), when compared with the corresponding binary composites (BMO/GNFs and CDs/BMO) and pure BMO. Our study revealed that the photocatalytic performance of ternary composite CDs/BMO/GNFs was significantly affected by the loadings of CDs or/and GNFs in BMO. Especially, the optimized sample C5/BMO/GNF-0.2, which was synthesized with a Bi/C molar ratio of 0.2 and the addition of 5 mL CDs, exhibited the best activity in the photocatalytic degradation of RhB. It was found that 99.4% of RhB was removed after 70-min exposure to the simulated solar light irradiation. This was attributed to the synergistic effects between components (CDs, BMO and GNFs) and heterojunctions, resulting in an efficient spatial separation of the photogenerated electrons and holes. A possible photocatalytic mechanism of C5/BMO/GNF-0.2 was proposed that the photogenerated holes, O2− and OH radicals contributed to the photocatalysis, which was supported by the radical quenching experiment and electron spin resonance analysis.

Studies demonstrate that microRNA-126 plays a critical role in promoting angiogenesis. However, its effects on angiogenesis following ischemic stroke are unclear. Here, we explored the effect of microRNA-126-3p and microRNA-126-5p on angiogenesis and neurogenesis after brain ischemia. We demonstrated that both microRNA (miRNA)-126-3p and microRNA-126-5p increased the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) compared with the scrambled miRNA control (p < 0.05). Transferring microRNA-126 into a mouse middle cerebral artery occlusion model via lentivirus, we found that microRNA-126 overexpression increased the number of CD31+/BrdU+ (5-bromo-2′-deoxyuridine-positive) proliferating endothelial cells and DCX+/BrdU+ neuroblasts in the ischemic mouse brain, improved neurobehavioral outcomes (p < 0.05), and reduced brain atrophy volume (p < 0.05) compared with control mice. Western blot results showed that AKT and ERK signaling pathways were activated in the lentiviral-microRNA-126-treated group (p < 0.05). Both PCR and western blot results demonstrated that tyrosine-protein phosphatase non-receptor type 9 (PTPN9) was decreased in the lentiviral-microRNA-126-treated group (p < 0.05). Dual-luciferase gene reporter assay also showed that PTPN9 was the direct target of microRNA-126-3p and microRNA-126-5p in the ischemic brain. We demonstrated that microRNA-126-3p and microRNA-126-5p promoted angiogenesis and neurogenesis in ischemic mouse brain, and further improved neurobehavioral outcomes. Our mechanistic study further showed that microRNA-126 mediated angiogenesis through directly inhibiting its target PTPN9 and activating AKT and ERK signaling pathways. Keywords: angiogenesis, ischemic stroke, microRNA, neurogenesis, PTPN9

Evasion of apoptosis is a major contributing factor to the development of chemo- and radiotherapy resistance. Therefore, activation of non-apoptotic programmed cell death (PCD) could be an effective alternative against apoptosis-resistant cancers. In this study, we demonstrated in vitro and in vivo that metformin can induce pyroptosis, a non-apoptotic PCD, in esophageal squamous cell carcinoma (ESCC), a commonly known chemo-refractory cancer, especially at its advanced stages. Proline-, glutamic acid- and leucine-rich protein-1 (PELP1) is a scaffolding oncogene and upregulated PELP1 in advanced stages of ESCC is highly associated with cancer progression and patient outcomes. Intriguingly, metformin treatment leads to gasdermin D (GSDMD)-mediated pyroptosis, which is abrogated by forced expression of PELP1. Mechanistically, metformin induces pyroptosis of ESCC by targeting miR-497/PELP1 axis. Our findings suggest that metformin and any other pyroptosis-inducing reagents could serve as alternative treatments for chemo- and radiotherapy refractory ESCC or other cancers sharing the same pyroptosis mechanisms.

This paper numerically investigates the influence of masonry infill walls on collapse mechanisms of steel frames under fire scenarios. Three six-story by five-bay steel frames were designed in this study. One of these frames had no infill walls, another one had horizontal infill walls, and the last one had vertical infill walls. Load redistribution and fire resistance were investigated under edge bay fire scenario and central bay fire scenario. The numerical results indicated that masonry infill walls provide alternate load paths in fire conditions, causing significantly large variations of axial forces in surrounding columns. Furthermore, the lateral resistance of the infilled frames is provided by the integral loading resisting system under edge bay fire scenario. The infill walls decrease the buckling temperature and increase the collapse temperature of the heated columns. A series of parametric analyses were performed to investigate the factors influencing the fire resistance of the steel frames. Finally, a preliminary design method was proposed with an aim to prevent the collapse of steel frames with infill walls under fire scenarios.

This study revised the non-radial angle model and set up the meta-frontier non-radial angle efficiency (MNAE) model. Moreover, an angle efficiency index was established in the MNAE model to reflect changes in the production decisions of decision-making units as a result of the external environment. The study conducted empirical analysis on data for 30 provinces in China from 2004 to 2015. The results showed that the eastern area of China was sensitive to fluctuations in the world’s economy and was able to quickly adjust production decision making; the western area lagged relatively behind in making changes, and the central area was not affected. Effects of international trade and foreign direct investment on the Shandong, Jiangsu, Fujian, Liaoning, Hunan, Henan, Jiangxi, and Sichuan provinces were significant and caused notable policy changes, which led to short-term resource waste and policy faults. This study also provides policy advice based on the results.

Chronic obstructive pulmonary disease (COPD) is characterized by increased cellular stress and inflammation. Heat shock protein 60 (HSP60) is a highly conserved stress protein that acts as a cellular "danger" signal for immune reactions. In this study, we investigated the role of HSP60 in COPD and explored the underlying mechanisms. Expression levels of HSP60 in patients with acute exacerbation of COPD (AECOPD), stable COPD, and healthy people were detected by Western blotting and enzyme-linked immunosorbent assay (ELISA). Moreover, the effect and molecular mechanism of HSP60 in COPD were studied in cigarette smoke (CS)-treated C57BL/6 mice and macrophages. The results showed significant upregulation of HSP60 expression in the peripheral blood mononuclear cells (PBMCs) and sera of patients with AECOPD compared to those with stable COPD or healthy people. CS induced the expression of HSP60 in the COPD mouse model, accelerated the activation of toll-like receptor 4 (TLR4) and NLR family pyrin domain containing 3 (NLRP3) signalling pathways, promoted the increase of inflammatory cells in alveolar lavage fluid and serum inflammatory factors, and induced destruction of lung tissue structure. Furthermore, HSP60 knockdown affected TLR4 and MyD88 expression, IκBα degradation, and nuclear localization of NF-κB and NLRP3 inflammasome activity. Our study revealed that CS stimulates the expression of HSP60, activating the TLR4-MyD88-NF-κB signalling pathway and the NLRP3 inflammasome.

As an important transcription and pluripotency factor, Sox2 plays its functions essentially in the regulation of self-renewal and pluripotency of embryonic and neural stem cells, as well as embryogenesis, organogenesis, neurogenesis and regeneration. The data is lacking on Sox2 in large yellow croaker (Larimichthys crocea) (Lc-Sox2) which is a limitation on the generation of induced pluripotent stem cells (iPSCs). In this study, Lc-sox2 was cloned by RACE (rapid amplification of cDNA ends) and analyzed by Bioinformatics. The quantitative real-time PCR (qRT-PCR) and whole mount in situ hybridization (WISH) were used to detect the expression of Lc-sox2. The full-length cDNA sequence of Lc-sox2 is 2135 bp and encodes a 322-aa (amino acids). Lc-Sox2 possesses a highly conserved HMG-box as DNA-binding domain, maintains highly conserved with vertebrates, particularly with teleosts. In tissues, Lc-sox2 was expressed with gender difference in brain and eye (female > male), in embryos, Lc-sox2 was expressed with a zygotic type that the high level expression began to appear in the gastrula stage. The spatio-temporal expression patterns of Lc-sox2 suggested the potential involvement in embryogenesis, neurogenesis, gametogenesis and adult physiological processes of large yellow croaker. Our results contributed to better understanding of Sox2 from large yellow croaker.

Background Current quality control methods for traditional Chinese patent medicines (TCPMs), e.g., microscopy, thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC), cannot detect herbal species composition with adequate precision. To address this issue, more effective detection methods should be explored. Hypothesis/Purpose We hypothesized that shotgun metagenomic sequencing can fulfill the requirements for the species detection of multi-ingredient TCPMs. Methods Longdan Xiegan Wan (LDXGW), once thought to be the chief culprit in aristolochic acid nephropathy (AAN), was selected to establish the method. It was used for both reference and commercial LDXGW samples. The precision authentication of herbal species contained in multi-ingredient TCPM is based on the shotgun metagenomic sequencing of genomic DNA without PCR amplification. Chemical analyses were also conducted as a contrast test. Results Over 100 G of raw data was obtained, and this value represented more than 0.75 billion reads. After assembling and filtering all the reads, a total of 261 contigs were obtained, which belonged to the ITS2, psbA-trnH, and matK regions of the reference and commercial samples. Because the homology of the rbcL region was high, it was not analyzed in the HTS data. Bioinformatics analysis indicated that the ITS2 region, as a DNA barcode, showed the highest identification efficiency. It could successfully detect all prescribed species, including four processed herbal ingredients, in the lab-made reference samples. The commercial samples all met the requirements of the Chinese Pharmacopoeia according to the TLC and HPLC tests. However, the shotgun metagenomic sequencing detected the substitution of Akebiae Caulis (Mutong) in the commercial samples, while the chemical analyses could not distinguish. Conclusion The results highlight that shotgun metagenomic sequencing is a complementary method for the precise species detection of TCPMs.

This paper examines the relationships among environmental regulations (ER), staff quality (SQ), R&D efficiency (RDE), green technology (GT), and profit. The research sample comprises 1197 firms in 16 manufacturing industries in China, during 2008 and 2015. DEA-based measures are employed to research firm RDEs, and the results show that SQ is essential for high RDE and GT (as expected), but the main effects of SQ are mixed. Importantly, we find that ER moderates the SQ-GT, SQ-RDE and SQ-profit relationships. Specifically, if ERs are eased, SQ is of limited benefit to GT or profit. However, at or above the ER threshold level, firms can improve SQ for further improvements in GT and profit. The implications of our findings on theory and practice are also discussed.

In this work, highly dispersed and different morphologies of Co 3 O 4 on the surface of GO modified with polyethylenimine (PEI) were synthesized by hydrothermal method at different temperatures. Co 3 O 4 /PEI-GO exhibited better gas sensing properties for NO x gas than the pure Co 3 O 4 and Co 3 O 4 /GO. Especially, the Co 3 O 4 /PEI-GO composite with hydrothermal at 190 °C for 3 h showed excellent sensitive characteristics to NO x at room temperature. The cause of good gas sensing property come mainly from the synergy between Co 3 O 4 and graphene oxide (GO) modified with PEI, which can significantly enhance the gas sensing performance. The adsorption species of NO x on the surface of Co 3 O 4 /PEI-GO composite sensor was detectable by In Situ Diffuse Reflectance Infrared Transform Spectroscopy (DRIFT). The electronic core-shell configuration model has been established to illustrate the resistance change when the Co 3 O 4 is exposed to oxidizing gases. Hence, the Co 3 O 4 /PEI-GO composite materials are promising in application of detecting NO x gas sensing.

This study proposes a mathematical definition of environment-biased technological progress that can evaluate energy saving and emission reduction abilities. Further, it proposes the concepts of absoluteness and relativity, while extending the classical non-radial slack-based measure in order to establish an advanced slack-based measure model. In addition, a super-efficiency advanced slack-based measure model is set up to test the effectiveness and growth rate of environment-biased technological progress in China. Finally, with China entering a new normal since 2012, economic growth data for 1890 coal production enterprises for 2012–2014 are collected to measure the conditions of environment-biased technological progress in each location and registration type. The results indicate that, compared to existing methods, the proposed method is useful and universally applicable.

Two series of bis-β-diketonate Eu3+ complex/polymer hybrid fibers, namely, Eu2(BTP)3(H2O)4/PMMA (Eu/PMMA) and Eu2(BTP)3(H2O)4/PVP (Eu/PVP) have been prepared by electrospinning technology (BTP = 1,3-bis(4,4,4-trifluoro-1,3-dioxobutyl)phenyl, PVP = poly (vinyl pyrrolidone) and PMMA = poly (methyl methacrylate)). The effect of complex Eu2(BTP)3(H2O)4 on the luminescence, thermal stability and morphology of composite fibers were studied by characterization techniques. The Judd-Ofelt theory was applied to this study for explaining the effect of the distribution of Eu2(BTP)3(H2O)4 and the mutual effect of the Eu2(BTP)3(H2O)4 coordination compound and neighboring chain segments of PMMA and PVP polymer matrix.

In this study, a single tubular section of the rectangular utility tunnel project in Shenyang city, China was simulated by applying a Finite Element Method. To increase the simulation accuracy, reinforcing steel bars were practically added to the utility tunnel model. Using the equivalent static loading method, the potential failure modes of rectangular utility tunnel at different buried depths were equivalently modeled by changing the imposed loads on the roof and side wall. Uniform pressure was applied on the top surface of roof, and a linear change in lateral earth pressure was extended on the external surface of side wall. Two tensile stress concentration zones were observed on the top surface of the roof, and one tensile stress concentration zone was observed on the external surface of side wall, easily leading to cracking on the surface concrete of these zones. These tensile stress concentration zones are named as “easy cracking zones” in this study. The effect of span size and corner type of rectangular utility tunnel on the easy cracking zones was then studied; the results provide a theoretical reference for the future design of rectangular utility tunnels.

Innovation is an important driving force for realizing high-quality green development of the marine economy. Based on the innovation value chain, this study incorporates three marine waste pollutants into the two-stage marine innovation efficiency research framework and uses the super-efficiency DEA model to measure the overall efficiency and sub-process efficiency of the marine innovation of China’s coastal regions from 2006 to 2016. We apply the dynamic panel model and the threshold effect model to empirically test the impact of marine industrial agglomeration and environmental regulation on the efficiency of two-stage marine innovation. We find that (1) during the inspection period, the overall efficiency average of China’s marine innovation was 0.99; the marine green RD and the commercialization efficiency average was 1.31. At this stage, the improvement of marine innovation efficiency depends on commercialization efficiency and is restricted to green R&D efficiency. (2) An obvious inverted U-shaped relationship exists between marine industrial agglomeration and marine innovation. Environmental regulations play a significant positive role in promoting marine innovation. (3) An environmental regulation threshold exists in the process of marine industrial agglomeration that affects both the overall and the commercialization processes.

The poly[2,7-9-(9-heptadecanyl)-9H-carbazole-co-benzo[4,5] imidazole[2,1-a]isoindol-11-one] (PCz-O) was synthesized by Suzuki coupling reaction, which structure was verified by FT-IR, 1H NMR and 13C NMR. The spin coating method was used to prepare RRAM devices based on PCz-O: ZrO2 nanoparticle active layer, and the devices exhibited ternary switching. Through a series of performance tests, both pure polymer device and composited with ZrO2 NPs devices had ternary storage characteristics. Among them, the content of composited with 8 wt% ZrO2 showed the most excellent ternary storage characteristics. The ON/OFF current ratio was 2.60 × 104, and the threshold voltage Vth1/Vth2 was −0.60 V/-1.00 V. The current is stable for 10000 s in both ON/OFF states. After 3300 times of reading, the switch state current of the devices had slight variation. In addition, the switching mechanism of the device was also discussed. Through carefully testing and analyzing, the devices had good stability and durability, and had potential application value in terms of data storage.

Laser shock peening is a surface treatment technology inducing high-pressure shock waves on metallic materials and structures. In this study, the life cycle performance improvement in high-strength steel by nanosecond laser shock peening is investigated. It is found that microstructures formed by laser shock peening lead to higher microhardness, corrosion resistance, and fatigue life, which are significantly beneficial for preventing life cycle failure of mega-scale engineering structures in critical environments. The residual stress is also measured on the surface of samples, which shows that the compressive residual stress can be found in the treated area.

Detecting and monitoring the damage locations of in-service reinforced concrete (RC) structures is difficult as they exhibit more complex geometries and consist of composite materials. In this study, a new method for detecting the source location of acoustic emission (AE) signals in RC structures using machine learning was introduced and tested on an in-service RC column. An impulse response test was conducted using an AE testing system to gather data regarding the source locations. Meanwhile, the source locations on the test column were generated through manual hits. The corresponding AE data were collected using a AE data acquisition system. The significant AE parameters were determined using neighborhood component analysis for feature selection to obtain a dataset for machine learning. Further, a support vector machine classifier was adopted to classify the source locations of the columns for three sensor groups. Furthermore, the source locations were predicted using feedforward backpropagation neural networks. This study validated the detectability of AE signals in RC columns and proposed a novel detection method, which can be employed to perform continuous nondestructive tests on in-service RC columns.