In Situ Test and Numerical Analysis of the Subway-Induced Vibration Influence in Historical and Cultural Reserves.

Although the rapid expansion of urban rail transit offers convenience to citizens, the issue of subway vibration cannot be overlooked. This study investigates the spatial distribution characteristics of vibration in the Fayuan Temple historic and cultural reserve. It involves using a V001 magnetoelectric acceleration sensor capable of monitoring low amplitudes with a sensitivity of 0.298 V/(m/s2), a measuring range of up to 20 m/s2, and a frequency range span from 0.5 to 100 Hz for in situ testing, analyzing the law of vibration propagation in this area, evaluating the impact on buildings, and determining the vibration reduction scheme. The reserve is divided into three zones based on the vertical vibration level measured during the in situ test as follows: severely excessive, generally excessive, and non-excessive vibration. Furthermore, the research develops a dynamic coupling model of vehicle-track-tunnel-stratum-structure to verify the damping effect of the wire spring floating plate track and periodic pile row. It compares the characteristics of three vibration reduction schemes, namely, internal vibration reduction reconstruction, periodic pile row, and anti-vibration reinforcement or reconstruction of buildings, proposing a comprehensive solution. Considering the construction conditions, difficulty, cost, and other factors, a periodic pile row is recommended as the primary treatment measure. If necessary, anti-vibration reinforcement or reconstruction of buildings can serve as supplemental measures.

In Situ Collection and Rapid Detection of Pathogenic Bacteria Using a Flexible SERS Platform Combined with a Portable Raman Spectrometer.

This study aims to develop a simple, sensitive, low-cost, environmentally friendly and flexible surface-enhanced Raman scattering (SERS) platform, combined with a portable Raman spectrometer, for the rapid and on-site SERS detection of bacteria. Commercial tobacco packaging paper (TPP) with little background interference was used as a loading medium that effectively adsorbed Au nanoparticles and provided sufficient "hot spots". This Au-tobacco packaging paper (Au-TPP) substrate used as a flexible SERS platform can maximize sample collection by wiping irregular surfaces, and was successfully applied to the on-site and rapid detection of pathogenic bacteria. Raman fingerprints of pathogenic bacteria can be obtained by SERS detection of spiked pork using wipeable Au-TPP, which verifies its value in practical applications. The results collected by SERS were further verified by polymerase chain reaction (PCR) results. It showed several advantages in on-site SERS detection, including accurate discrimination, simple preparation, easy operation, good sensitivity, accuracy and reproducibility. This study indicates that the established flexible SERS platform has good practical applications in pathogenic bacterial identification and other rapid detections.

Nutrient Removal by Floating Treatment Wetlands Under Different Spatial Arrangement Modes: a Field Study.

Floating treatment wetlands (FTWs) are a management method to improve urban rivers, but most studies have been carried out at laboratory, micro, and meso levels, so it is necessary to study full-scale FTWs as a method to improve urban water bodies. In this experiment, the purification effects of water temperature (WT), dissolved oxygen (DO), ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), total phosphorus (TP), chemical oxygen demand (CODMn), and chlorophyll-a (Chl-a) under staggered arrangement (SA) and centered arrangement (CA) were evaluated. It was found that the DO concentration and removal rate of CODMn, Chl-a, and TP in the SA were significantly higher than those in the CA in months with heavy rainfall. However, interestingly, for TP, August showed the opposite trend. The removal rates of NH4+-N and NO3--N were significantly different throughout the test period. The biomass growth values of shoots and roots of plants in the FTWs were 0.40 ± 0.03 kg/m2 and 1.38 ± 0.07 kg/m2 in the SA and 0.32 ± 0.07 kg/m2 and 1.26 ± 0.30 kg/m2 in the CA. The increments of N absorbed by plants in the SA and CA were 7.08 ± 0.49 g/kg and 6.83 ± 0.07 g/kg, respectively, and the increments of P were 0.57 ± 0.02 g/kg and 0.32 ± 0.07 g/kg, respectively, which indicated that the growth status of plants in the FTWs in the SA was slightly better than that in the CA. In summary, the hybrid-constructed FTWs of both arrangements can effectively improve the water quality of urban rivers, and the effect of the SA was greater than that of the CA. The purification effect of in situ tests under different arrangement modes of hybrid-constructed FTWs was evaluated, which provides guidance and support for the field layout of FTWs in rivers in the future.

Instrumented Cone Penetrometer for Dense Layer Characterization.

Subsurface characterization is essential for a successful infrastructure design and construction. This paper demonstrates the use of an instrumented cone penetrometer (ICP) for a dense layer characterization at two sites. The ICP consists of a cone tip and rods equipped with an accelerometer and four strain gauges, which allow dynamic driving, in addition to quasi-static pushing of the cone. The force and velocity of the cone are measured using the ICP instrumentation and compared with the N value, dynamic cone penetration index, and static cone resistance. A strong correlation has been observed between the total cone resistance estimated from the ICP and the dynamic cone penetration index and static cone resistance. After the correction of the dynamic cone resistance effect, the static component of the total cone resistance can be used as an alternative to a static cone resistance. This novel approach of soil resistance estimation using the ICP may be useful for dense layer characterization.

Bacterial diversity of biofilms on polyhydroxybutyrate exposed to marine conditions: Ex-situ vs. in-situ tests.

Biofilms form on any available surface and, depending on the characteristics of the material and the environmental conditions, biodegradation can take place. We compared the bacterial composition of polyhydroxybutyrate (PHB)-related biofilm communities from marine ex-situ and in-situ tests to assess the differences in diversity and abundance between these two biofilms. This comparison will help to better assess the transferability of tank tests to real-life scenarios. The in-situ tests were set up in the Mediterranean Sea on the Island of Elba, Italy where PHB-tensile bars were lodged in the sediments. This created a water-exposed aerobic and mud-planted anaerobic scenario. The ex-situ tests were modeled after in-situ tests and performed in temperature-controlled tanks. The PHB-related biofilms were harvested after 240 days of exposure along with planktonic bacteria, and particle- and sediment-related biofilm. The bacterial composition was elucidated using 16S rDNA sequencing. Biofilms harvested from the in-situ test were more diverse, less even, and contained more rare species compared to biofilms from the ex-situ test. The PHB-related biofilm was characterized by a higher abundance of the bacterial order Desulfobacterales. The composition of PHB-related biofilm varied significantly between the two tests and between aerobic and anaerobic conditions. The composition of PHB-related biofilm was significantly different from planktonic bacteria, particle, and sediment-related biofilm, showing the influence of PHB on the biofilm composition. Thus, the ex-situ tank test for PHB degradation cannot, in terms of bacterial composition, simulate the in-situ conditions to their full extent.

The Effect of the Energy Release Rate on the Local Damage Evolution in TRIP Steel Composite Reinforced with Zirconia Particles.

In this study, the effect of the energy release rate on the transformation-induced plasticity (TRIP) steel composite reinforced with 5 vol% ceramic particles is determined using the crystal plasticity simulation of the coupled brittle-ductile damage model and validated by experimental results. A miniature dog bone tensile sample is subjected to an interrupted in situ quasi-static tensile test up to a true strain of 20.3%. Using the commercial digital image correlation program VEDDAC and the image processing method in MATLAB, the test data are utilized to monitor the progress of local microstrain and damage. The impact of the energy release rate of ceramic particles is investigated by simulation using a coupled crystal plasticity-dislocation density model with ductile-brittle criteria for the corresponding phases. It can be shown that the local deformations predicted by the numerical simulation and the experimental data are qualitatively comparable. The damage pixel of the experiment, smaller Ecr (1.0 × 108), and larger Ecr (1.2 × 108) cases of energy release rates are 4.9%, 4.3%, and 5.1%, respectively. Furthermore, on a global strain of 20.3%, the relative error between simulation and experimental validation of smaller Ecr (1.0 × 108) and larger Ecr (1.2 × 108) cases is 12.2% and 4%, respectively.

Early Age Shrinkage and Mechanical Effect of Ultra-High-Performance Concrete Composite Deck: A Case Study with In Situ Test and Numerical Simulation.

For the Honghe Bridge project located in Yunnan Province, Southwest China, a steel/ultrahigh-performance concrete (UHPC) composite deck is used in the suspension bridge with a 700 m main span, and the steel stud connectors are used in the 50 mm-thick UHPC layer. To investigate the shrinkage behavior of UHPC and the relevant influence, the in situ time-dependent strain is measured continuously, and within the 20-day curing time, the material behavior is summarized based on test results. This paper proposes a prediction model for UHPC shrinkage which is refined from the widely used B3 model for normal concrete material, and the parameter values are modified and optimized by experimental comparison. Combining the numerical model and the finite element analysis model of the composite deck, the detailed mechanical state in structural parts is studied. For the practical construction, the simulation results indicate that the small thickness of UHPC above the stud and weak bond strength can influence the eventual structural performance greatly. In the discussion of stress distribution at different locations of the deck, the potential crack on the edge and the corner of the UHPC-steel interface and the mechanical damage on the stud connector around are also indicated.

Indirect Determination of Residual Prestressing Force in Post-Tensioned Concrete Beam.

A diagnostic survey on the precast prestressed bridge Nizná confirmed significant deterioration due to environmental distress. Evidently, decisive failures of the structure have a similar character as in the previous precast prestressed bridge in Podbiel in the northern part of Slovakia. These failures result from the unsuitable concept of the first generation of precast prestressed concrete beams, which was used in the former Czechoslovakia in the second half of the 20th century. Subsequently, experimental verification using the proof-load test was also executed. This bridge was built in 1956, so at the time of testing, it was 60 years old. The paper presents the indirect determination of prestressing level in one precast post-tensioned concrete beam using the saw-cut method. Experimental measurement was executed during the bridge demolition. Subsequently, a 2D numerical model in ATENA 2D Software, with the assumption of nonlinear material behavior for verification of experimental results, was performed. Finally, the residual prestressing force was evaluated and compared with the expected state of prestressing according to Eurocodes after 60 years of service.

Experimental data on the development of "Post-installed Screw Pullout test" for in-situ investigation of concrete strength.

This data article describes the datasets obtained during the development phase of "Post-installed Screw Pullout (PSP) test", a new in-situ test for concrete strength assessment. The datasets presented focus on the results obtained in mortar samples. The presented PSP test method is based on a post-installed screw being pulled from the parent material. To implement this, the screws installed in mortar sample were loaded to failure and the responses were recorded in the form of load-displacement curves. The samples were tested for two types of screw under different test conditions, with variables that included hole depth, hole diameter and mortar strength. These datasets are associated with the article "The Post-installed Screw Pullout Test: Development of a Method for Assessing In-situ Concrete Compressive Strength" (Al-Sabah et al., 2020).

A simplified management of the in situ evaluation of feedstuffs in ruminants: Application to the study of the digestive availability of protein and amino acids corrected for the ruminal microbial contamination.

The ruminal effective degradability (RED) and intestinal effective digestibility (IED) for dry matter, crude protein (CP) and amino acids (AA) were estimated by a simplified in situ method using pooled samples from rumen-incubated residues, which represented the ruminal outflow of undegraded feed. The effect of microbial contamination in the rumen was corrected using (15)N infusion techniques. Studies were carried out for soybean meal (SBM), barley grain (BG) and lucerne hay (LH) in three wethers cannulated in the rumen and the duodenum. Uncorrected values of RED for CP obtained either by mathematical integration or our simplified method were similar in all feeds. Microbial N in the pooled samples of SBM, BG and LH were 2%, 11% and 24% of total N, respectively. However, intestinal incubation eliminated this microbial charge by 100%, 99% and 88%, respectively. With microbial corrections, RED showed an increase, and IED showed a decrease, except for SBM. With this correction, intestinal digested CP was reduced by 2% in SBM, 13% in BG and 34% in LH. Corrected IED of AA was relatively similar in SBM (97-99%). However, large variations were observed in BG (74-93%) and in LH (10-88%). Digestion in the rumen and intestine changed the essential AA pattern. Overall, our results support that AA digestion is affected by the characteristics of their radicals and their contents in plant cell wall proteins. The accurate estimation of feed metabolisable AA or protein requires effective measures that are corrected by ruminal microbial contamination. The proposed in situ method largely simplifies these tasks and allows a more complete and less expensive feed evaluation.

The use of the SPT-based seismic soil liquefaction triggering evaluation methodology in engineering hazard assessments.

Probabilistic and deterministic seismic soil liquefaction triggering methodologies are proposed in Cetin et al. [1]. This manuscript: i) presents the protocols, which need to be followed for the correct use of this methodology for forward engineering (design) assessments, ii) guides the engineers through the procedure, and iii) discusses the "tricks" alongside the protocol. An illustrative soil profile shaken by a scenario earthquake is presented, through which consistent estimations of representative SPT blow-counts along with fines content are discussed. Additionally, the estimation of CSR input parameters are illustrated. Last but not least the uncertainty estimations of these input parameters are presented along with the probability and factory of safety for the assessment of liquefaction triggering. •A simplified methodology and its use to assess liquefaction triggering hazard of a soil site under an earthquake scenario event.•The consistent and unbiased mean estimates of input parameters of SPT blow-counts( N 1,60 ), fines content ( F C ), vertical effective ( σ ' v ) and total ( σ v ) stresses, maximum ground acceleration ( a m a x ), stress reduction (or non-linear shear mass participation) factor ( r d ) and moment magnitude ( M w ) along with their uncertainties are discussed.•Outlined methodology enables engineers to estimate the probability of- and factor of safety against- seismic soil liquefaction triggering for design problems.

Hydrogen-enhanced cracking revealed by in situ micro-cantilever bending test inside environmental scanning electron microscope.

To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel in situ micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, in situ H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10-4 Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane.This article is part of the themed issue 'The challenges of hydrogen and metals'.

Metals bioaccumulation and biomarkers responses in the Neotropical freshwater clam Anodontites trapesialis: Implications for monitoring coal mining areas.

As one of the most impactful industries, coal mining can promote several alterations at surrounding environment. In surface water, elevated concentrations of metals like Mn, Zn, Fe and Al are often observed. Thus, the aim of this study was to investigate the bioaccumulation and the sub-lethal effects of these metals on various organs of the Neotropical bivalve Anodontites trapesialis confined along a stream located near a coal mine, in order to assess a set of biomarkers that could be used for effectively monitoring coal mining areas. Clams were caged, for 96h, at two sites located upstream (Up1 and Up2) and two sites downstream (Dw1 and Dw2) from the mine. Metals bioaccumulation was determined in gills, mantle, digestive gland, muscle and hemolymph and the following biomarkers were measured in A. trapesialis tissues: total antioxidant capacity against peroxyl radicals, metallothionein content, lipid peroxidation (LPO), proteins carbonylation, glutathione S-transferase activity, superoxide dismutase activity and acetylcholinesterase (AChE) activity. The results showed that Al and Fe bioaccumulation in the gills and hemolymph, Al bioaccumulation in the mantle and muscle, increased LPO in the gills (Dw1 and Dw2) and mantle (Dw1), as well as reduced AChE activity in the muscle (Dw1 and Dw2) should be considered effective biomarkers for monitoring coal mining areas. A. trapesialis proved to be an efficient biological model, considering that biomarkers responses were observed in the clams after only 96h of confinement at Dw sites, accordingly this species could be a good candidate for monitoring Neotropical freshwaters.

Biomarkers in the freshwater bivalve Corbicula fluminea confined downstream a domestic landfill leachate discharge.

Landfills represent a severe environmental problem mainly due to the generation of leachates, and this study aimed to evaluate sublethal effects of a domestic landfill leachate in the freshwater bivalve Corbicula fluminea. Clams were submitted to in situ tests along a stream, at three sites, representing increasing distances from the leachate discharge (Pq1, Pq2, and Pq3), for 1, 5, and 15 days. The following biomarkers were analyzed in the gills and digestive glands: 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST) activities, multixenobiotic resistance mechanism (MXR), total antioxidant capacity (TAC), reactive oxygen species (ROS), and lipid peroxidation (LPO). Metallothionein (MT) content was determined in the gills and DNA damage in hemocytes. The mortality rate of animals during in situ tests was reduced as the distance from the leachate discharge source increased. On the other hand, biomarker results showed sublethal effects on C. fluminea confined at all sites of PqS. GST, TAC, ROS, and DNA damage were the most significant biomarkers for this species and should be considered for future monitoring and assessment of freshwater environments located in landfill areas.