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Diesel exhaust particles (DEPs) are major constituents of air pollution and associated with numerous oxidative stress-induced human diseases. In vitro toxicity studies are useful for developing a better understanding of species-specific in vivo conditions. Conventional in vitro assessments based on oxidative biomarkers are destructive and inefficient. In this study, Raman spectroscopy, as a non-invasive imaging tool, was used to capture the molecular fingerprints of overall cellular component responses (nucleic acid, lipids, proteins, carbohydrates) to DEP damage and antioxidant protection. We apply a novel data visualization algorithm called PHATE, which preserves both global and local structure, to display the progression of cell damage over DEP exposure time. Meanwhile, a mutual information (MI) estimator was used to identify the most informative Raman peaks associated with cytotoxicity. A health index was defined to quantitatively assess the protective effects of two antioxidants (resveratrol and mesobiliverdin IXα) against DEP induced cytotoxicity. In addition, a number of machine learning classifiers were applied to successfully discriminate different treatment groups with high accuracy. Correlations between Raman spectra and immunomodulatory cytokine and chemokine levels were evaluated. In conclusion, the combination of label-free, non-disruptive Raman micro-spectroscopy and machine learning analysis is demonstrated as a useful tool in quantitative analysis of oxidative stress induced cytotoxicity and for effectively assessing various antioxidant treatments, suggesting that this framework can serve as a high throughput platform for screening various potential antioxidants based on their effectiveness at battling the effects of air pollution on human health.

Rainwater retention and water content in green roofs are primarily influenced by structural configurations (i.e., soil layer, vegetation layer, and water storage layer) and climatic factors (i.e., rainfall and evapotranspiration (ET)). Based on the principle of water balance, this study proposes a conceptual model for simulating water flow in green roofs with water storage layers. Three green roof model experiments were conducted from August 1st, 2020 to July 31st, 2021 for calibrating and verifying the conceptual model. The proposed model was solved iteratively using a newly developed program in Visual Basic. The results showed that the conceptual model can capture the dynamic variations in the rainwater retention and water content of green roofs well. The average Nash-Sutcliffe efficiency coefficient is 0.65 and the average error is 6%. The annual rainwater retention capacity (RRC) of green roofs in the perennial rainy climate model was on average 28% higher than that in the seasonal rainy climate model. At the expense of water stress, high ET plants significantly increased the annual RRC of green roofs at a low level. As the water storage layer depth increased from zero to 150 mm, the annual RRC of green roofs increased by 41%, and the water stress decreased by 49%. Compared with an increase in water holding capacity and soil depth, the response of the annual RRC and water stress of green roofs for increasing water storage layer depth is much greater. As per climate of Southern China region, the water storage layer depth of 100 mm is found to obtain optimal rainwater retention and irrigation management in green roof with similar soil thickness (100 mm).

Vertical forests comprise of high-rise buildings with trees planted on their balconies. When trees are planted on a building, they change its exterior, and may influence local wind pressure and global aerodynamic forces. Wind-borne debris caused by local extreme wind pressures lead to negative effects on living environments, and large acceleration responses induced by global aerodynamic forces result in occupants’ uneasiness. Therefore, it is important to investigate the local and global wind loads on vertical forests. In this study, wind tunnel tests of simultaneous multi-channel pressure measurement were conducted to investigate the effects of trees on local wind pressures (mean and fluctuating wind pressures on different positions of building facades). High-frequency-base-balance (HFBB) wind tunnel tests were performed to probe the impacts of trees on the global aerodynamic force of the building (base bending and torsional moments). Pressure measurements reveal that trees have minimal effects on mean and extreme values of wind pressure on windward and leeward facades; however, trees decrease the values of extreme wind pressure at the separation area. The results of HFBB show that vegetation slightly increases the intensity of mean global wind load at along-wind directions, decreases the peak value of power spectral density (PSD) of lift forces corresponding to vortex shedding. In general, trees on balconies reduce wind pressures at separation area as well as the across-wind fluctuating forces for the building with the side ratio of 1.67. However, there is no significant effects on the rest of wind pressures and loads. Therefore, to some extent, trees planted on balconies were found to improve wind-resistant performance of vertical forests compared with conventional high-rise buildings.

Presence of vegetation in urban landscape influences soil temperature and soil moisture. Some studies in literature have focused on development of correlations between the above two parameters for agricultural fields and forest regions. These correlations could be dissimilar due to the differences in soil conditions (density and type), vegetation species and temperature between agricultural and urban landscape. This paper investigates the effects of vegetation on soil temperature and soil moisture by an integrated approach of field monitoring and numerical modelling. A simple hydrological model is developed to capture seasonal variations of surface soil temperature and its effect on root water uptake. Hypothesis of effects of soil temperature on root water uptake was investigated using field measurements of soil water content. Field site in urban landscape containing bare, grass and tree species were selected for investigation. There existed a contrasting trend in water content response between summer and autumn for both bare and vegetated soils. Due to higher evapotranspiration in summer, water content in vegetated soils were lower by up to 50%. However, water content in vegetated soil was found to be up to 70% higher than in a bare soil during autumn. It could be due to the lower soil temperature that inhibits root water uptake ability. This was verified using a series of numerical simulations that consider effects of soil temperature on root water uptake. Without considering soil temperature effects on root water uptake, there was an overestimation of reduction of soil water content by up to 50% in autumn period.

The long-term performance of green infrastructures (e.g., vegetated slopes, green roof, bio-retention systems, etc.) can be affected by the wilting of vegetation (i.e., tendency of evapotranspiration (ET) to be nil) attributed to the decrease in volumetric soil water content. Therefore, it is important to explore an approach to investigate the wilting time of vegetation so that mitigation measures can be taken to ensure the serviceability of green infrastructure. The technical note aims to 1) conduct probabilistic analysis of volumetric soil water content in slopes vegetated with non-crop tree and grass species; and 2) further explore this analysis method for estimating probability of wilting (tendency of transpiration becoming nil) of the selected vegetation species under natural climate conditions. For this investigation, two non-crop species namely, Ivy tree (Schefflera heptaphylla) and Bermuda grass (Cynodon dactylon), commonly grown in subtropical regions in world were selected. A normal distribution was found as the best fit to the measured volumetric water content under the impact of both species. The estimated mean value was found significantly higher in Cynodon dactylon slope compared with that of Schefflera heptaphylla slope, while the coefficient of variation among the species is similar. The probability of wilting of C. dactylon is found lower than that of Schefflera heptaphylla. In the present study, the significance of using probabilistic approach for characterizing the distribution of volumetric soil water content to assess the reliability of vegetated infrastructure was highlighted. The study is useful for estimating the behaviour of vegetation for better planning of restoration and rehabilitation measures. This differs from those in agricultural fields with the usually shorter period for monitoring of vegetation growth (mostly within 3 months), and they are usually subjected to controlled manual irrigation.

Meticulous research has been done to observe and measure the impact of biochar on soil-water retention properties. On the contrary, very little research is conducted on quantifying cracking in soil biochar composites. Investigation of crack intensity factor is essential as it affects permeability and hence, overall water balance in agricultural fields. It is well known that cracking of soil is influenced by suction and water content but their interactive effects are not very well understood. This technical note aims to investigate the cracking of soil amended with biochar made out of water hyacinth, an invasive weed, with focus on analysing interactive effects of water content and soil suction. An integrated reduced scale monitoring and modelling using artificial neural networks have been adopted. A series of tests were conducted to monitor suction, water content and crack intensity factor in soils mixed with four different compositions i.e. 0%, 2%, 5% and 10% by weight of biochar for around 3 months. The measured results have been evaluated first, and eventually modelled using artificial neural networks to predict crack intensity factor as function of water content and suction for all composites. In most of the cases it has been found that suction is more influential than water content. However, the relative significance of suction to water content in determining crack intensity factor decreases with increase in biochar content of soil. It is concluded that the optimum biochar content is 10% for most of the agricultural purposes based on the water retention capacity and cracking. The probability distribution of crack intensity factor is found to be normal for case with 5% biochar and while for others, it is skewed negatively. A simple cost based analysis taking in context of a small developing urban city of India, showcased a cost savings in irrigation of urban infrastructure by around 63,000 US dollars for a particular summer.

Evapotranspiration was determined to be hydrological effect which induces suction. Evapotranspiration induced suction governs the slope stability, ground water recharge and runoff. This study focuses on suction induced in root zone of mix grass used in green infrastructure. Most of the previous studies focused on evapotranspiration induced suction less than 100 kPa measured using tensiometers. However, for investigating the drought condition, it is essential to obtain suction data greater than 100 kPa. It was noted that the response of plant parameters such as stomatal conductance and surface area were not considered holistically evapotranspiration induced suction. The main objective of this study is to investigate relationship among evapotranspiration induced suction, stomatal conductance and surface area for a mix grass species used in green infrastructure subjected to drought stress (corresponds to suction > 100 kPa). Stomatal conductance was observed to increase up to suction (6 ± 1 kPa) corresponding to volumetric field capacity. Thereafter, large decrease (more than 90%) in stomatal conductance was found with an increase in suction. Stomatal conductance was found to be 0 at 2431 kPa (i.e., wilting point). Change in normalized surface areas of mix grass was found to be relatively low (within ±15%) with an increase in suction up to 138 kPa. However, beyond 138 kPa, it varied drastically (by 31–68%) with an increase in suction from 138 kPa to 3642 kPa. Two new relationships i.e., Stomatal conductance characteristic curve (SCCC) and surface area characteristic curve (SACC) were proposed. Therefore, the relationships developed in current study help to analyze the performance of green infrastructure accurately.

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.g. suction and water retention) of soil. However, variations in densities alter the properties of the soil–biochar mix. Such density variations are observed in agriculture (loosely compacted) and engineering (densely compacted) applications. The influence of biochar amendment on gas permeability of soil has been barely investigated, especially for soil with different densities. The major objective of this study is to investigate the water retention capacity, and gas permeability of biochar-amended soil (BAS) with different biochar contents under varying degree of compaction (DOC) conditions. In-house produced novel biochar was mixed with the soil at different amendment rates (i.e. biochar contents of 0%, 5% and 10%). All BAS samples were compacted at three DOCs (65%, 80% and 95%) in polyvinyl chloride (PVC) tubes. Each soil column was subjected to drying–wetting cycles, during which soil suction, water content, and gas permeability were measured. A simplified theoretical framework for estimating the void ratio of BAS was proposed. The experimental results reveal that the addition of biochar significantly decreased gas permeability kg as compared with that of bare soil (BS). However, the addition of 5% biochar is found to be optimum in decreasing kg with an increase of DOC (i.e. kg,65% > kg,80% > kg,95%) at a relatively low suction range (

Sustainable biomaterials such as natural fibers and biochars have been increasingly used in green infrastructures such as landfill covers for its dual-advantages of climate change mitigation and waste management. The existing studies did not systematically discuss the comparison on how biochar (stable carbon) and fiber (likely degradable), influence plant growth and water retention abilities in unsaturated soils. Also, the effect of photochemistry in the amended soils has rarely been investigated. This study addresses the limitations of previous investigations by exploring plant parameters such as photochemical yield, stomatal conductance, root area index, and unsaturated soil hydraulic parameters, including soil water retention curves (SWRC) of amended soils. Pot experiments were conducted in an environmentally controlled greenhouse. Two biochars from different plant-based feedstocks (Eichhornia crassipes, Prosopis juliflora) and one natural fiber (coir pith fiber) were mixed with soil at 5% and 10% application rate (by weight). Grass species of Axonopus compressus was planted to study the effects of different amendment materials and its corresponding plant responses during an applied drought period. The test results show that biochar amended soils increased the shoot growth by up to 100−200%. The stomatal conductance of the grass leaves increased by 54%−101% during the drought period for both biochars and coir amended soil. Furthermore, at low suction, the coir had a high water retention capacity than the biochars, explaining the observed higher stomatal conductance values. Importantly, it was discovered that the plant photochemical quantum yield responses associated with plant wilting was found to vary between 1500 and 1800 kPa for all the soil treatments. The study concludes with a newly developed mathematical expression based on the measurements of plant parameters and soil suction. The new equation could be used to optimize the irrigation frequency in order to apply any informed measures to maintain green infrastructures.

This study evaluates the effects of root morphology and depth on the enhancement of induced suctions in soil grounds due to transpiration. Root morphology is idealized as uniform, triangular, parabolic and exponential distributions based on observations and the transpiration process is governed by the modified Richards equation. The study reveals that the exponential and triangular root networks enhance soil suctions more remarkably than the uniform and parabolic patterns. With the same total root amount, a root network with most of root amount concentrated in the superficial zone can induce significantly higher suction values than a root system distributed deeply.

A 2-year field study was conducted with wheat (Triticum aestivum L.) - green gram (Vigna radiata L.) crop rotation in an inceptisol to compare the effect of vermicompost and biochar on soil organic carbon (SOC), its fractions and carbon mineralization when applied with inorganic fertilizers. Experimental treatments used were only inorganic nitrogen, phosphorus and potassium (NPK) at recommended dose as control, 50% N + PK, NPK + vermicompost (2.5 t ha−1), NPK + biochar (2.5 t ha−1), 50% N + PK + vermicompost (5 t ha−1) and 50% N + PK + biochar (5 t ha−1). Compared to lone application of inorganic fertilizers, application of organic amendments significantly increased the total organic carbon (4–10%), particulate organic carbon (POC) (5–21%), microbial biomass carbon (MBC) (40–55%), recalcitrant carbon (F4) (16–67%), humic acid carbon (HAC) (2–12%) and fulvic acid carbon (FAC) (8–37%). Higher concentration of labile carbon fractions (F1 and F2), POC and MBC were noted with vermicompost application while addition of biochar produced more stable carbon fractions (FAC, HAC and F4). Vermicompost application increased (5–15%) the C mineralization rate with higher (29–55%) soil respiration, and lower (35–58%) C half-life compared to biochar. Principal component analysis confirmed a close association among the stable C fractions (FAC, HAC and F4) and degree of humification. Labile carbon fractions (F1, F2 and MBC) indicated higher sensitivity to the applied fertilizers. Biochar application promoted higher leaf and root biomass in the tested crops whereas the grain yields were not significantly (P ≤ 0.038) different suggesting equal potentiality of both the amendments towards productivity. The benefit cost ratio was higher (1.89 and 2.89) for application of vermicompost but greater agronomic efficiency (0.10 and 0.12 kg kg−1) and lower (10–22%) soil available nitrogen content were noted with biochar application, which indicates environmental sustainability. Thus, biochar introduction into the fertility program of wheat-green gram crop rotation along with inorganic fertilizers would be a better option which not only uphold crop productivity but also sequester higher SOC compared to vermicompost.

New analytical solutions of pore-water pressure (PWP) distributions in a vegetated multi-layered slope are derived considering the effects of roots on water permeability. PWP distributions are significantly affected by root-induced reductions in water permeability due to increases in the root volume ratio (Rv). Under drying conditions, negative PWP increases with Rv. The negative PWP induced by root water uptake increases with the desaturation coefficient (αi) or the ratio of the transpiration rate to saturated water permeability (Tp/ksi). As the overall water permeability underneath the vegetation layer decreases, the negative PWP induced by root water uptake increases.

Water hyacinth (WH), is one of the world's most intractable and invasive weed species. Recent studies explored the efficacy of this species as a biochar (BC) in improving soil fertility and metal adsorption. However, the soil water retention (SWR) property and crack potential of soil-WH biochar composite has still not been studied. The major objective of this study is to investigate the SWR property and corresponding crack intensity factor (CIF) for compacted soil-WH BC composites. Soil-WH BC composites at five percentages (0, 2, 5, 10 and 15) was compacted and soil parameters such as suction (ψ), water content and CIF were simultaneously monitored for 63 days (including 9 drying-wetting cycles). Results showed that soil-WH BC composite at all percentages retains more water (max. 19% and min. 6.53%) than bare soil at both saturated and drought conditions. Gradual inclusion of WH BC to soil decreases the CIF potential from 7% to 2.8%.

Many previous studies of soil contaminant treatment have primarily analysed heavy metal contaminant ion retention in fly ash (FA) in a single isolated medium whereas, factoring out the competitive systems. This study seeks to determine the interaction of the heavy metal copper ion (Cu+2) with fly ash under single and competitive systems and also to expound its impact on fate prediction. Freundlich and Langmuir non-linear isotherms were adopted to quantify the sorption results. The retardation factor attained from Freundlich isotherm predicts more than Langmuir. The Langmuir isotherm break-through-curves (BTC) was slightly earlier in break through, with a sharp front and prolonged tailing, whereas the Freundlich isotherm appears considerably after the production of a spreading pollutant front. Freundlich retardation factors established in this study was employed to one-dimensional (1-D) solute transport model, which successfully stimulated good prediction for sorption by fly ash. Conversely, significant inconsistencies were identified from the Langmuir isotherm for evaluating the fate of Cu+2 at high concentration range. This study recommends Freundlich isotherm for modelling transport of copper ions in a competitive environment in fly ash.

The concept of vertical forests is gaining popularity as it promotes the coexistence of architecture and nature in urban areas. The wind loads and dynamic responses of buildings may be impacted by the presence of vegetation. A wind-induced motion equation of vertical forests was formulated in the preliminary stage of research, assuming that tree cover is enclosed with curtain wall. The model was used to analyze a case. We used the time history of wind pressure attained from wind-tunnel tests of the host structure to calculate wind-induced responses. To investigate the contribution of the vegetation, three cases were analyzed: the original structure, the vertical forest and the host structure with an ETMD (equivalent tuned mass dampers). The impact exerted by tree cover with specific parameters on wind-induced responses was analyzed. The results show that tree cover significantly reduces vibration of the host structure under the action of wind loads, though the vibration-absorbing effects exerted by tree cover are less than that of the ETMD. Parametric analysis indicated that vibration-absorbing effects are more susceptible to the variation of natural frequency of tree cover than its damping ratio.

In this paper, considering the strain softening effect, the cavity expansion theory is improved for over-consolidated soil. Based on the theory of cavity expansion model, the soil around the pile is divided into three zones namely damage zone, plastic zone and elastic zone. This is divided according to the distance from pile. Considering the strain soften effect of over-consolidated soil, cavity cylinder balance equation is modified in the damage zone. The residual shear strength is introduced instead of the conventionally adopted peak shear strength. The effect of shear stress on excess pore water pressure is ignored in the plastic zone. With this development, large deformation plasticity theory was applied to modify the equation. Expressions and relations were derived to consider pile expansion stress of the damaged zone, excess pore water pressure, the radius of the damaged zone and plastic zone. Based on newly proposed model, it can be concluded that (1) With the increase of the pile expansion stress, plastic flow and strain softening appear in the damage zone, and there are rotations of principal stresses; (2) for the normally consolidated soil, the radius of the damage zone is about 5–6 times larger than the pile diameter. However, for the over-consolidated soil, the radius of the damage zone is 16.7%–20% smaller; (3) the excess pore water pressure increases with the increase in over consolidation ratio, whereas, it decreases significantly with the increase of the distance to the pile; (4) effective transmission radius of expansion stress is about 5–7 times larger than the diameter of the hole around the pile. The range can be considered as the boundary value of the plastic zone. Based on the theoretical deduction and numerical calculation of the hydrostatic pile, the mechanism of the pile penetration mechanism and its influence on the surrounding soil environment are summarized.

With growing importance of green infrastructure, sustainable natural fibers such as coir and jute are extensively used for shallow depth embankment reinforcement. The motivation of the study is to investigate the reinforcing potential of an invasive weed species (water hyacinth) for subgrade reinforcement and juxtapose its reinforcing efficacy with that of the conventionally used coir and jute fibers. For such a comparison, a series of unconfined compression strength (UCS) tests was conducted on clayey silt reinforced with randomly distributed fibers extracted from the selected species. The results were used to study the influence of different fiber percentages, soil-fiber composite density and moisture content on the strength improvement factor (SIF) of the soil-fiber composite. Further, the test results were used to study the soil-fiber composite ductility using all three fibers. To explain the soil-fiber composite ductility, two new physical parameters has been identified. Among the three fibers tested, jute showcased the highest strength in majority of the tested conditions. However, coir and WH fibers are equally competent for increasing SIF at least by 50%. Among the tested soil-fiber composite, coir reinforced soil showcased highest ductility at the tested conditions, which is attributed to its high elongation at break. The post peak ductility of soil-fiber composite is dependent mainly on the fiber percentage and the compaction state. This is mainly governed by the development of fiber bridges in the shear band and also due to “lubrication” effect.

Vegetation induces considerable uncertainties in the hydrological (suction, ψ) and mechanical (cohesion, c and frictional angle, ϕ) parameters of soil, due to which, it is essential that the stability of vegetated slope is evaluated in a probabilistic framework. Moreover, from previous studies, it has been found that the mechanical parameters of soil share inherent correlation, which has a profound effect on slope stability. The combined effect of stochastic hydro-mechanical parameters is not well studied, more so in vegetated slopes. This study demonstrates a probabilistic approach to analyse the stability of vegetated slopes, under the combined effect of univariate suction and bivariate c − ϕ. Data corresponding to suction and the mechanical parameters, are obtained from a field monitoring programme, conducted on a homogeneously compacted vegetated slope (adopted from previous literature). The suction responses are probabilistically evaluated by estimating their probability distribution functions, and the dependence structure of c and ϕ is established via copula theory. Treed slopes are found to be more stable than grassed and bare (i.e. sparsely vegetated) slopes, since suction induced in treed soil is relatively higher. The probability of failure for vegetated slopes decreases substantially with increase in magnitude of c − ϕ correlation, thereby yielding more conservative estimates than the uncorrelated case.

Spatial heterogeneity of vegetation growth is important for maintenance of urban green space. It also governs the differential settlement of foundation of buildings and performance of biofiltration units. The objective of this study is to analyse the heterogeneity in vegetation density and shoot growth of a grass around a tree vicinity. A novel non-intrusive image analysis approach was designed and developed for quantifying heterogeneity in vegetation growth. A commercially available unmanned air vehicle (UAV; PHANTOM 3 STANDARD) was utilized to capture images. Vegetation density from these captured images were quantified using a public domain image processing program ImageJ. Atmospheric parameters were monitored by micro-climate monitoring system for interpreting vegetation growth. It is found that, at a given radial distance from stem of tree, vegetation density range is found more heterogenous than shoot growth. The basic assumption of symmetricity around tree vicinity as adopted in previous models for root water uptake is found to be not true. Variation of rainfall is one of the main reason causing heterogeneity in grass growth around tree vicinity. Heterogeneity in vegetation growth more prominent near the tree vicinity than away from it. An increase in vegetation density is found within 2 m radial distance in both sides of tree stem due to presence of shredded leaves from tree during winter.

A structured comprehensive curriculum (SCC) that uses simulation-based training (SBT) can improve clinical colonoscopy performance. This curriculum may be enhanced through the application of progressive learning, a training strategy centered on incrementally challenging learners. We aimed to determine whether a progressive learning-based curriculum (PLC) would lead to superior clinical performance compared with an SCC.This was a single-blinded randomized controlled trial conducted at a single academic center. Thirty-seven novice endoscopists were recruited and randomized to either a PLC (n = 18) or to an SCC (n = 19). The PLC comprised 6 hours of SBT, which progressed in complexity and difficulty. The SCC included 6 hours of SBT, with cases of random order of difficulty. Both groups received expert feedback and 4 hours of didactic teaching. Participants were assessed at baseline, immediately after training, and 4 to 6 weeks after training. The primary outcome was participants' performance during their first 2 clinical colonoscopies, as assessed by using the Joint Advisory Group Direct Observation of Procedural Skills assessment tool (JAG DOPS). Secondary outcomes were differences in endoscopic knowledge, technical and communication skills, and global performance in the simulated setting.The PLC group outperformed the SCC group during first and second clinical colonoscopies, measured by JAG DOPS (P .001). Additionally, the PLC group had superior technical and communication skills and global performance in the simulated setting (P .05). There were no differences between groups in endoscopic knowledge (P.05).Our findings demonstrate the superiority of a PLC for endoscopic simulation, compared with an SCC. Challenging trainees progressively is a simple, theory-based approach to simulation whereby the performance of clinical colonoscopies can be improved. (Clinical trial registration number: NCT02000180.).

The newest digital photogrammetric technology is applied to investigate the deformation characteristics of rock mass when it changes from open pit to underground mining. First, the calculation formulas of pixel deformation and instrumental error were derived. Based on this, the calculation of digital camera calibration were obtained and used to calibrate the physical model for rock mass undergoing the changing mining process. Finally, the deformation characteristics of rock mass were revealed based on a geotechnical engineering of Daye iron mine and the monitored results of digital photogrammetry were compared with the dial indicators. It was found that the surface deformations measured by digital photogrammetric technique are similar to the results using dial indicators. The maximum error between these two was less than 0.02 mm. These tests demonstrate the efficacy of digital photogrammetry as a powerful technique for deformation measurement in the geotechnical model tests.

Hydraulic conductivity of a vegetated soil (i.e., mixed grass cover) is an important parameter governing the hydrological performance of green infrastructure (GI). This paper focuses on GI with mixed grass cover in the presence of trees. Due to shading effects (interception of radiant energy) of tree canopy, mixed grass cover in the vicinity of trees may not receive direct photosynthetically active radiation (PAR). This can hinder the growth rates resulting in the low grass cover (i.e., in density). The hydraulic conductivity and the performance of GI can be further affected. Several field studies were conducted to investigate hydraulic conductivity in different types of vegetated covers. However, any variation in growth and hydraulic conductivity of mixed grass cover in the vicinity of trees was rarely investigated. The objective of this study is to quantify spatial and temporal variation of vegetation growth and hydraulic conductivity in a mixed grass cover in the vicinity of a tree. Field monitoring of a mixed grass cover in the vicinity of a tree in a GI was conducted for about six months. Hydraulic conductivity tests were carried out using mini disk infiltrometer (MDI) at 149 locations in a selected site once every month. Vegetation density was quantified using image analysis and the images were captured by a DJI Phantom drone. The growth of mixed grass cover around tree vicinity (within 5 m radial distance) was found to be more uniform during months characterized by high rainfall depth. Spatial heterogeneity in both vegetation density and hydraulic conductivity is found to be more significant during a dry period than wet period. Variation of hydraulic conductivity with respect to the change in vegetation density is found to be significant in a wet period than dry period. It is also found that hydraulic conductivity is higher at the portions where shredded leaves are present. The obtained dynamic spatio-temporal relationship of soil, vegetation and atmospheric parameters can support the design of green infrastructures and contribute to a better understanding of the maintenance practices.

It is unlikely that natural vegetation growth induced soil suction can be predicted deterministically. Probabilistic approach may be an ideal tool to analyse effects of evapotranspiration (ET) induced suction by vegetation, which are commonly found on slopes. Most of the previous deterministic studies quantifying suction are carried out on natural slopes, which are heterogeneous in nature. The main objective of this study is to conduct probabilistic analysis of measured soil suction in homogeneously vegetated slopes. In the present work, a probabilistic model is developed for the measured values of suction, since the measurement process itself is very uncertain and is subjected to a wide range of climatic fluctuations owing to a wide monitoring interval. Expected values of soil suction are found to be significantly higher in treed slope as compared to grassed and bare slope. In contrast to this, the coefficient of variation of soil suction is found to be similar for all slopes irrespective of vegetation types. The probability distribution is found to be dynamically changing with time and also significantly different between bare slope (Weibull distribution) and the vegetated slopes (mostly Normal distribution). Using the estimated probability distributions of suction, the probability of failure is estimated using a simple limit state function using 1000 trials of Monte-Carlo simulation. It is observed that the distribution of suction alters significantly for bare soils during wetting events as compared to the grassed and treed soils. The probability of failure of the bare slopes increases significantly under wetting events.

Biochar has been globally recognized as a soil amendment to ameliorate the degraded soil structures. We investigated the different biochar percentages contributed to the changes in soil water retention, soil infiltration, and water-holding capacity of one dimensional scale. Besides, infiltration models were compared, and an improved genetic algorithm (GA) combined with multi-objective optimization and elitist strategy was proposed to upgrade the modified van-Genuchten (VG) model. Results indicated that observed cumulative infiltration displayed reductions by 14.06%, 46.62%, and 71.78% for the soil mixed with 5%, 10%, and 15% biochar, respectively, relative to the pure soil. The Kostiakov model was more effective than the Philip model in predicting cumulative infiltration. Furthermore, the constructed modified VG model based on the inversed hydraulic parameters was capable of predicting soil moisture at suction less than 2070 kPa (i.e., 1.38 times wilting point) but caused an underestimation beyond it. This research has the potential to replace the soil water retention curve (SWRC) measurement by one-dimensional infiltration experiment with parameters inversed from the improved GA combined with a modified VG model. It is time-saving and efficient during the SWRC study.

The practical application of determination of the soil water retention curves (SWRC) is in seepage modelling in unsaturated soil. The models based on the physics behind the seepage mechanism has been developed for predicting the SWRC. However, those models rarely consider the combined effects of initial volumetric water content and soil density. One of the best routes to study these effects is to formulate the SWRC models/functional relations with volumetric water content as an output and the soil density, initial volumetric water content and soil suction as input parameters. In light of this, the present work introduces the advanced soft computing methods such as genetic programming (GP), artificial neural network and support vector regression (SVR) to formulate the volumetric water content models based on the suction, density and initial volumetric water content. The performance of the three models is compared based on the standard measures and goodness-of-fit tests. The findings from the statistical validation reveals that the GP model performs the best in generalizing the volumetric water content values based on the suction, density and initial water content. Further, the 2-D and 3-D plots, evaluating the main and the interaction effects of the three inputs on the volumetric water content are generated based on the parametric procedure of the best model. The study reveals that the volumetric water content values behave non-linearly with respect to soil suction because it first decreases till a certain point of soil suction and then increases suddenly.

Compressive strength and direct shear testing parameters on unsaturated soil are often used in analysis and design of several geotechnical infrastructures. Rarely, any attempt has been made to quantify shear strength of unsaturated soil under different net normal stress conditions. The objectives of this study are to quantify shear strength parameters of unsaturated silty sand and to establish a simple correlation of it with unconfined compressive strength. Consolidated drained direct shear tests and unconfined compressive strength tests were performed to determine shear strength of unsaturated completely decomposed granite (CDG) soil. To interpret this, a series of typical soil water characteristic curves (SWCC) of CDG soil under different net normal stresses were also measured. Experimental results show that the unsaturated shear strength significantly increases with increase in net normal stress and matric suction. A new model for prediction of unconfined compression strength of unsaturated soil from shear strength and initial suction was proposed. The predictions from newly proposed model were found to be consistent with the measured unconfined compressive strength. This correlation can be useful in economical and rapid design/analysis of geotechnical infrastructure.

Phytoremediation, is a promising biochemical process which has gained wide acceptance in remediating the contaminants from the soil. Phytoremediation process comprises of biochemical mechanisms such as adsorption, transport, accumulation and translocation. State-of-the-art modelling methods used for studying this process in soil are limited to the traditional ones. These methods rely on the assumptions of the model structure and induce ambiguity in its predictive ability. In this context, the Artificial Intelligence approach of Genetic programming (GP) can be applied. However, its performance depends heavily on the architect (objective functions, parameter settings and complexity measures) chosen. Therefore, this present work proposes a comprehensive study comprising of the experimental and numerical one. Firstly, the lead removal efficiency (%) from the phytoremediation process based on the number of planted spinach, sampling time, root and shoot accumulation of the soil is measured. The numerical modelling procedure comprising of the two architects of GP investigates the role of the two objective functions (SRM and AIC) having two complexity measures: number of nodes and order of polynomial in modelling this process. The performance comparison analysis of the proposed models is conducted based on the three error metrics (RMSE, MAPE and R) and cross-validation. The findings reported that the models formed from GP architect using SRM objective function and order of polynomial as complexity measure performs better with lower size and higher generalization ability than those of AIC based GP models. 2-D and 3-D surface analysis on the selected GP architect suggests that the shoot accumulation influences (non-linearly) the lead removal efficiency the most followed by the number of planted spinach, the root accumulation and the sampling time. The present work will be useful for the experts to accurately determine lead removal efficiency based on the explicit GP model, thus saving the waste of input resources.

Unsaturated permeability in soil is useful in assessment of water consumption by roots and suction distribution in slopes, which in turn, helps in design for the stability of slopes/covers. Stress factor is important in understanding the behavior of the unsaturated soils because it has a significant effect on its permeability as it brings micropores and minipores changes in the soil structure. Past studies have often neglected to measure its effect on the permeability property of the soil. The present study will introduce an optimization framework of genetic programming (GP) in developing the explicit relation of the permeability and the stress of the unsaturated clay. Experimental validation of the GP model will be done using the metrics such as the coefficient of determination, the root mean square error and the mean absolute percentage error. 2-D analysis of the model will be useful for experts to monitor the permeability property unsaturated clay.

The stability and serviceability of geotechnical infrastructure may be affected by plant-induced soil suction during drying–wetting cycles, because an increase in suction would reduce hydraulic conductivity and also increase shear strength. Recent studies have been conducted to quantify suction induced during evapotranspiration (ET) and ponding in soil vegetated with non-crop species that are used for the ecological restoration of geotechnical infrastructure. However, induced suction distribution under drying–wetting cycles is rarely studied. The objectives of this study are to (1) quantify suction induced by a non-crop tree species, Schefflera heptaphylla, under ponding–drying–ponding cycles and (2) correlate intercepted radiant energy, tree leaf area index (LAI), extinction coefficient (k) and root area index (RAI) with suction. In total, 18 vegetated soil samples with LAI ranging from 0.9 to 3.1 and three bare soil samples (control) were tested and subjected to identical cycles of ET and ponding. Energy balance calculation was performed to determine the percentage of interception of radiant energy. An almost linear relationship can be seen between the percentage of energy intercepted (from 7% to 42% ± 4%) and LAI (from 0.9 to 3.1 ± 0.09) for S. heptaphylla. The measured value of k for S. heptaphylla (0.13) was found to be much lower than that of some crop species (0.4–1.6) reported in the literature. Peak suction is always identified at the depth, where RAI is maximum. It was further demonstrated that the tree-induced suction has a strong linear correlation with both the RAI and LAI.

The presence of vegetation in the upper layer of vadose zone results in complex moisture dynamics (soil-root-water interaction) due to the combined effects of transpiration and soil water evaporation. Unsaturated soil-root composite hydraulic properties, transpiration and soil water evaporation and effect of plant parameters (i.e., leaf area index (LAI), root length density (RLD) and root area index (RAI)) on soil property are keys for understanding this complex moisture dynamics. Previous studies have not collectively discussed these plant parameters and unsaturated soil properties to understand moisture dynamics in the vadose zone. The main objective of this review is to identify the gaps and lay out future studies that need to be addressed between unsaturated soil mechanics and plant parameters. These gaps are discussed in the context of agricultural field and bioengineered slopes (a type of slope remediation). The hydraulic properties of soil-root composite (water retention curve, hydraulic conductivity) are discussed with respect to soil composition, soil density and cracked soil. Influences of plant parameters, such as LAI, RLD and RAI on boundary conditions are discussed. For scheduling irrigation schemes and analyzing crop yield and water use efficiency, bare soil hydraulic properties were incorporated instead of rooted soil hydraulic properties by previous researchers. For analyzing the stability of bioengineered slopes, plant parameter influence was not taken into account. The efficacy of soil-root composite water retention curve (SRCWRC) incorporation in the field of agriculture as well as geotechnical engineering (i.e., for bioengineered slope stability analysis), is demonstrated in this review. The study proposes the incorporation of aging effect of plants, temporal variation of root distribution and consideration of LAI variation with altitude; in applications related to both agricultural field and bioengineered slope stabilization.

Maintenance of green infrastructure requires persistent monitoring of soil water content, electrical conductivity (EC), temperature and relative humidity (RH). There is need to create relation among these parameters to deduce soil water content as to limit cost of introducing sensors. The present investigation means to measure the progression of these four parameters in a green infrastructure site in an urban landscape and to additionally create correlations among them. An incorporated field testing and statistical modeling approach is embraced to accomplish the objective. Four sites including bare, grassed and treed soil are chosen for examination. Field monitoring was first directed to monitor the above mentioned four parameters for two months. This is trailed by statistical modeling using artificial intelligence (AI) approach (i.e., artificial neutral networks (ANN)). Correlations are created for evaluating soil water content as function of EC, RH and temperature for the four sites. Regardless of the sort of cover, EC is strongly correlated to soil water content, followed by RH and soil temperature. The correlation of EC is strongest in vegetated soil when compared with bare soil. The relationship of soil temperature with water content of soil do not have a decisive pattern. Ensuring drying of soils does not increase temperature fundamentally after precipitation. Uncertainty investigation additionally presumes that water content of soil follows normal distribution function in treed soils, while it follows skewed distribution in the cases of grassed and bare soils.

Vegetation is essential in constructing eco-slopes for environmental protection and restoration, as well as in minimizing soil erosion and landslide. The effects of vegetation on the hydraulic properties of the underlying soil cover, especially the saturated-unsaturated hydraulic properties during long-term drying-wetting cycles, are extremely important to assess the performance of an eco-slope, which have not been intensively investigated. This study investigated the infiltration and hydraulic conductivity of the vegetated covers by continuously monitoring the hydraulic properties of three different vegetated layers for a period of four years. Thirty-three sensors were set up to monitor the hydraulic properties of a Vetiver grass cover, a Bermuda grass cover and a bare cover in-situ. The results demonstrate that the infiltration rate through the Vetiver grass cover is almost two times that of the cover without vegetation. In contrast, the infiltration rate through the Bermuda grass cover is only half of the bare cover. The hydraulic conductivity of the Vetiver cover is larger than that of the bare cover and increases up to 3 orders of magnitude. The unsaturated hydraulic conductivity of the Bermuda cover is the smallest, which only increased by 1–2 orders of magnitude under the same matric suction in four years. The field study indicates that the Bermuda grass can effectively reduce the increase in percolation of a soil layer. This study provides valuable field data to clearly demonstrate the influence of vegetation on the covers, paving the way for a more sustainable ecological slope design.

Computed Tomography technique has been commonly used to obtain the geometric model of asphalt mixture for the microstructure-based heat transfer numerical analysis. However, this technique relies on expansive equipment and has shortcomings related to limited sample size and difficulty in identifying the boundary of stones. This study proposes a cost and time-effective numerical method to compute the heat transfer within asphalt mixture from the microstructure point of view. The computer graphics technique is adopted to develop the geometric model of asphalt mixture, including coarse stones and asphalt matrix. The generated geometric model is imported into the finite element software to compute the thermal conductivity and specific heat capacity of asphalt mixture. To obtain input parameters of the newly developed numerical method, the thermal conductivity and specific heat capacity of coarse stones and asphalt matrix are measured through the heat plate exchanger. The above two parameters of asphalt mixture are also measured to verify the computed results by the newly developed numerical method. The differences between computed and measured thermal conductivity and specific heat capacity of asphalt mixture are 9.0% and 8.6% respectively, indicating a good performance of the newly proposed microstructure-based numerical approach. On the other hand, computed results show that asphalt mixtures with different sample sizes and aggregate size distributions have non-uniform distributions of heat flux and temperature, mainly due to the different thermo-physical properties between coarse stone and asphalt matrix. For asphalt mixtures, a knowledge of heat flux and temperature fluctuations from the microstructure point of view may shed light on the analysis of stress/strain distribution and crack propagation in asphalt mixture.

Biochar is a stable carbon-rich product obtained through pyrolysis of plant and animal-based biomass. Soil is often amended with biochar due to the beneficial features, such as carbon sequestration, improvement of crop growth and yield by enhancing soil fertility, removal of an organic and inorganic pollutant from the soil, and improvement of water retention properties of the soil. Fundamentally, the amendment of soil with biochar alters the soil water retention characteristics (SWRC) of the soil. This is primarily due to the inherent properties of biochar that includes large specific surface area (SSA) by the intra-particle pores, and the functional groups present in biochar surface. SWRC is vital for both agricultural soil and soil in geotechnical or geo-environmental engineering structures due to the presence of vegetation. The effect of biochar on the SWRC of agricultural soil was extensively studied. However, it is rarely studied for soil in geotechnical or geo-environmental engineering structures, such as landfill cover, bioengineered slope, embankment, green roof, etc. Soil in these structures subjects to a distinct condition, in terms of compaction state and design life compared to agricultural soil. Therefore, a comprehensive gathering of information on the effect of biochar on the SWRC and the factors controlling the biochar influence is needed for potential investigation and application of biochar amendment for soil in geotechnical or geo-environmental engineering structures. In this article, the effect of biochar amendment on the SWRC of soil has been reviewed and summarized by considering various factors controlling the influence of biochar on the SWRC. The literature review revealed that the amendment of soil with biochar could improve the SWRC while few occasions not influence the SWRC. Factors, such as feedstock type and pyrolysis temperature, particle size of biochar, soil type, and compaction state have strong bearing on the influence of biochar on the SWRC.

Context We examined if empagliflozin was associated with modulation of cardiac autonomic tone among subjects with type 2 diabetes and stable coronary artery disease (CAD) relative to placebo. Methods Using ambulatory 24-h Holter electrocardiographic data prospectively collected from a randomized trial, we compared changes in heart rate variability (HRV) parameters between empagliflozin- and placebo-assigned subjects over a follow-up period of 6 months. Measured HRV domains included: standard deviation (SD) of NN intervals (SDNN), SD of average NN intervals per 5-min (SDANN), root mean square of successive RR interval differences (RMSSD), % successive NN intervals differing >50 ms (ms) (pNN50), low frequency (LF), high frequency (HF) and the LF/HF ratio (LF:HF). Differences in HRV parameters between the 2 groups were compared with analysis of covariance (ANCOVA). Statistical measures of significance were reported as adjusted differences between the 2 groups and their corresponding 95% confidence intervals. Results Sixty-six subjects completed 24-h Holter monitoring at baseline and 6-months. Over 6 months, the change in HRV was similar between subjects treated with empagliflozin vs. placebo for the following parameters: RMSSD -1.2 ms (-6.0 to 3.6 ms); pNN50 0.5% (-2.6 to 3.6%); VLF -907.8 ms2 (-2388.8 to 573.1 ms2); LF -341 ms2 (-878.7 to 196.7 ms2); HF -33.8 ms2 (-111.1 to 43.5 ms2); LF:HF -0.1 (-0.4 to 0.2). Subjects who received placebo experienced an increase in SDNN 18.6 ms (2.8–34.3 ms) and SDANN 20.2 ms (3.2–37.3 ms) relative to those treated with empagliflozin. Conclusion Compared to placebo, empagliflozin did not result in changes in autonomic tone among individuals with type 2 diabetes and stable coronary artery disease., Highlights • Sodium-glucose cotransporter-2 (SGLT2) inhibitors’ mechanism of cardiovascular benefit is unknown. • Impaired autonomic tone is associated with adverse cardiac events. • Cardiac autonomic tone was assessed with Holter studies from a randomized trial. • Similar autonomic tone noted between subjects treated with empagliflozin and placebo.

Landfill cover should ideally have a medium with high water retention ability and low hydraulic conductivity to prevent rainfall infiltrating into the hazardous waste layer. Even though biochar amended soil (BAS) is advocated as cover medium, the interactions between biochar and plant, as well as the effects of biochar aging and plant growth on soil hydraulic properties are still not clear. This study aims to investigate the effects of grass (Cynodon dactylon) growth in BAS on soil water retention and saturated hydraulic conductivity (ks) over a two-year period. Four ground conditions were tested, namely bare silty sand with and without biochar, vegetated silty sand with and without biochar. The biochar content was kept at 10% (v/v). During the first 6 months, soil water content corresponding to field capacity (FC) and permanent wilting point (PWP) in grassed soil increased by 17% and 27%, respectively. With biochar inclusion, 43% and 57% additional increases in FC and PWP respectively were observed. Moreover, ks in biochar-amended grassed soil decreased by 50%. Furthermore, grass growth from 6 to 24 months reduced FC by 32%, PWP by 40% but caused 20 times increase in ks of grassed soil. With the presence of biochar, FC and PWP decreased by only 6% and 8%, respectively, and ks increased by 200% due to the enhanced plant growth (specifically root growth) by biochar. After two years, ks of grassed soil with biochar was 16 times smaller than that without biochar. This study demonstrated the effectiveness of biochar in maintaining the enhanced soil water retention ability and reduced ks in vegetated soil over a two-year study period.

Growing awareness of sustainability in construction has increased attention toward increase in use of natural fibers for soil reinforcement applications. Researchers have explored the utility of natural limited life fibers such as jute, reed and sisal for soil reinforcement. In this study, an attempt was made to demonstrate the use of local weed named water hyacinth (Eicchornia crassipes) as soil reinforcement. A series of unconfined compression strength (UCS) tests was conducted on silty sand reinforced with randomly distributed fiber. These series of tests aim to study influence of different fiber content, soil density and moisture content. The stress–strain response of fiber reinforced soil shows the increase in post peak strength and ductility. This was mainly attributed due to presence of cellulose content. The effect of soil density on increased strength due to inclusion of fiber is significant in case of lower moisture content.

Quantifying soil suction induced by plant transpiration is vital for engineers to analyse the performance of geotechnical infrastructure such as landfill covers. Transpiration reduction function (T rf ) and root distribution function (R df ) are the two plant properties that govern root-water uptake ability. These two functions have been quantified for various crop species, but they are sometimes used to study the behaviour of non-crop species, even though these two functions are known to be plant-specific. In this study, specific T rf and R df were measured for six replicates of Schefflera heptaphylla that have a range of leaf area index (LAI) from 1.0 to 3.5 in clayey sand with gravel. S. heptaphylla is a non-crop tree species that has been commonly used for ecological restoration in many subtropical regions of the world. T rf of each replicate was obtained by relating normalized transpiration rate with suction. After testing, the root system of each tree individual was imaged to determine the normalized root area index (RAI) profile (i.e., R df ). The normalized transpiration rate for S. heptaphylla with higher LAI (3 and 3.5) is revealed to have lower tolerance of water stress as their normalized transpiration rate reduced at much lower suctions, as compared to those with lower LAI (i.e., 1–2.5). Only when suction is lower than 50 kPa, the measured T rf of S. heptaphylla is similar to some of those presumed in the literature. The measurement of R df shows that the maximum amount of roots for S. heptaphylla was at depths of 70–80% of the root depth, in contrast to crops species whose root distribution is typically uniform or linearly decreasing.

Plant evapotranspiration (ET) is considered to be a hydrological effect that would induce soil suction and hence influence the stability of geotechnical infrastructure. However, other hydrological effect, such as the change of soil water retention curve (SWRC) induced by roots, is generally ignored. This study aims to investigate and compare the effects of root-induced changes in SWRC with the effects of ET on suction responses in clayey sand. Two series of laboratory tests together with 21 numerical transient seepage analyses were conducted. A tree species, Schefflera heptaphylla, which is commonly used for ecological restoration in many subtropical regions, was selected for investigation. In order to consider any effects of tree variability on induced suction, six tree individuals with similar age were tested with and without the supply of light. It is revealed that under dark condition when ET was minimal, vegetated soil could induce higher suction than bare soil by 100% after subjecting to a wetting event with a return period of 100 years. This may be explained by the increases in the air-entry value and the size of hysteresis loop induced by roots. Water balance calculation from the numerical analyses shows that even under the supply of light, the amount of ET was only 1.7% of the total volume of water infiltrated. This means that during the wetting event, the contribution of root-water uptake to induced suction in vegetated soil was relatively little, as compared with the effects of root-induced change in SWRC.