Severe Environmental Conditions Research Articles

Insights on Fructans and Resistance of Plants to Drought Stress

Drought, one of the major abiotic stresses affecting plants, is characterized by a decrease of water availability, resulting in a decrease of the water potential (Ψ) of the cells. One of the strategies of plants in resisting to this low Ψ and related stresses is regulating their water-plant relation and the interplay between Ψsolutes and the turgor pressure (Ψp). This regulation avoids the dehydration induced by low Ψ and is resulting from the accumulation of specific molecules which induce higher tolerance to water deficit and also other mechanisms that prevent or repair cell damages. In plants, fructans, the non-structural carbohydrates (NSC), have other physiological functions than carbon reserve. Among these roles, fructans have been implicated in protecting plants against water deficit caused by drought. As an efficient strategy to survive to this abiotic stress, plants synthesize fructans in response to osmotic pressure in order to osmoregulate the cellular flux, therefore, protecting the membrane damage and maintaining Ψp. Although different studies have been conducted to elucidate the mechanisms behind this strategy, still the concept itself is not well-understood and many points remain unclear and need to be elucidated in order to understand the causal relation between water deficit and fructans accumulation during water scarcity. This understanding will be a key tool in developing strategies to enhance crop tolerance to stressful dry conditions, particularly under the changing climate prediction. This review aims to give new insights on the roles of fructans in the response and resistance of plants to water deficit and their fate under this severe environmental condition.

Properties and durability of partially replaced cement-based composite mortars co-using powders of a nanosilica superplasticiser and finely ground plastic waste

This paper was about an experimental work on properties and durability of partially replaced cement-based composite mortars. Substitutions equal to 0, 2, 4 and 6% of finely ground polyethylene (PE) in association with a 3% nanosilica superplasticiser (SP) were used to cast the composite mortars. Fresh properties concerned setting as well as compressive strength versus porosity accessible to water whereas hardened durability properties were investigated by carbonation according to FT-IR, chloride corrosion of reinforcement, total chloride ion content, steel bars losses of mass and nitric acid attack. The superplasticiser and polyethylene powder inhibited the hydration of the cement while the compressive strength decreased with the rise of the polyethylene content but remained higher than the control mortar one for a (PE) content not exceeding 4%. Composite mortars were less porous and experienced a 2.08% average porosity. Under carbonation, composite mortars exhibited similar performance with the control mortar while corrosion and steel bar mass losses readings revealed the passive condition of the composite mortars and a total chloride content less than 0.4%. Composite mortars demonstrated better resistance to nitric acid attack with (PE) content increase. Correlation of the SEM images and X-ray evidence with the experimental records may be an indication of the feasibility of providing composite mortars with an optimal 2% (PE) for concrete constructions under severe environmental conditions.

Preliminary Design and Dynamic Response of Multi-Purpose Floating Offshore Wind Turbine Platform: Part 1

Floating offshore wind turbine foundations are based on platforms operated by the oil and gas industry. However, they are designed and optimized to meet the wind turbines’ operating criteria. Although Malaysia is considered a low-wind-speed country, there are some locations facing the South China Sea that are found to be feasible for wind energy harnessing. The average daily wind speed may reach up to 15 m/s. Therefore, designing a cost-effective platform that can operate in Malaysian waters which has less severe environmental conditions compared to the North Sea would be a prudent undertaking. In this study, a new design of a multi-purpose floating offshore wind turbine platform (Mocha-TLP) is presented. In addition, the dynamic response of the platform to wave loads was investigated using the Navier–Stokes code STAR CCM+ developed by CD-adapco. Moreover, free-oscillation tests were performed to determine the natural periods of the platform. Three approaching wave cases and two wave conditions (WC) were considered. The results show that the natural periods of the platforms were within the recommended range for pitch, roll, yaw, heave, sway and surge motions. The platform was stable in rotational motion within the three cases. However, it experienced a noticeable surge motion which was more critical with wave condition one (WC1) since the wavelength equalled the length of the structure. The dynamic response of the platform to wave loads wase minimal and within the operational requirements for wind turbines.

NHX-Type Na+/H+ Antiporter Gene Expression Under Different Salt Levels and Allelic Diversity of HvNHX in Wild and Cultivated Barleys.

Salinity tolerance is a multifaceted trait attributed to various mechanisms. Wild barley is highly specialized to grow under severe environmental conditions of Tibet and is well-known for its diverse germplasm with high tolerance to abiotic stresses. The present study focused on determining the profile of the expression of isoforms of the HvNHX gene in 36 wild and two cultivated barley under salt stress. Our findings revealed that in leaves and roots, expression of HvNHX1 and HvNHX3 in XZ16 and CM72 was upregulated at all times as compared with sensitive ones. The HvNHX2 and HvNHX4 isoforms were also induced by salt stress, although not to the same extent as HvNHX1 and HvNHX3. Gene expression analysis revealed that HvNHX1 and HvNHX3 are the candidate genes that could have the function of regulators of ions by sequestration of Na+ in the vacuole. HvNHX1 and HvNHX3 showed a wide range of sequence variations in an amplicon, identified via single-nucleotide polymorphisms (SNPs). Evaluation of the sequencing data of 38 barley genotypes, including Tibetan wild and cultivated varieties, showed polymorphisms, including SNPs, and small insertion and deletion (INDEL) sites in the targeted genes HvNHX1 and HvNHX3. Comprehensive analysis of the results revealed that Tibetan wild barley has distinctive alleles of HvNHX1 and HvNHX3 which confer tolerance to salinity. Furthermore, less sodium accumulation was observed in the root of XZ16 than the other genotypes as visualized by CoroNa-Green, a sodium-specific fluorophore. XZ16 is the tolerant genotype, showing least reduction of root and leaf dry weight under moderate (150 mM) and severe (300 mM) NaCl stress. Evaluation of genetic variation and identification of salt tolerance mechanism in wild barley could be promoting approaches to unravel the novel alleles involved in salinity tolerance.

Highly efficient and stable perovskite solar cells enabled by low-dimensional perovskitoids.

Deep traps originated from the defects formed at the surfaces and grain boundaries of the perovskite absorbers during their lattice assembly are the main reasons that cause nonradiative recombination and material degradation, which notably affect efficiency and stability of perovskite solar cells (PSCs). Here, we demonstrate the substantially improved PSC performance by capping the photoactive layer with low-dimensional (LD) perovskitoids. The undercoordinated Pb ions and metallic Pb at the surfaces of the three-dimensional (3D) perovskite are effectively passivated via the Pb-I bonding from the favorably lattice-matched 3D/LD interface. The good stability and hydrophobicity of the LD (0D and 1D) perovskitoids allow excellent protection of the 3D active layer under severe environmental conditions. The PSC exhibits a power conversion efficiency of 24.18%, reproduced in an accredited independent photovoltaic testing laboratory. The unencapsulated device maintains 90% of its initial efficiency after 800 hours of continuous illumination under maximum power point operating conditions.

Intersections: photosynthesis, abiotic stress, and the plant microbiome

Climate change impacts environmental conditions that affect photosynthesis. This review examines the effect of combinations of elevated atmospheric CO2, long photoperiods, and/or unfavorable nitrogen supply. Under moderate stress, perturbed plant source-sink ratio and redox state can be rebalanced but may result in reduced foliar protein content in C3 plants and a higher carbon-to-nitrogen ratio of plant biomass. More severe environmental conditions can trigger pronounced photosynthetic downregulation and impair growth. We comprehensively evaluate available evidence that microbial partners may be able to support plant productivity under challenging environmental conditions by providing (1) nutrients, (2) an additional carbohydrate sink, and (3) regulators of plant metabolism, especially plant redox state. In evaluating the latter mechanism, we note parallels to metabolic control in photosymbioses and microbial regulation of human redox biology.

Quarry dust as river sand replacement in cement masonry blocks: Effect on mechanical and durability characteristics

Natural sand or river sand constitutes as major fine aggregate in cementitious construction. Especially, masonry block production requires 70–90% sand as raw material. While the demand for river sand increases rapidly, the supply of good quality river sand is limited due to the restrictions in sand mining in river beds. Because excessive extraction of river sand to cater the increasing demand has brought undesirable environment-related consequences. The persisting issues encouraged the researchers to find a sustainable alternative for river sand. Quarry dust is one of the alternatives as it has some advantages over river sand such as better contribution to the strength of the cementitious material, better workability, lesser cement consumption and eco-friendly. The present study explored the feasibility of using quarry dust as fine aggregate in manufacturing cement blocks. Cement blocks with four different quarry dust composition levels 0, 33.3%, 66.7 and 100%, were prepared and tested. The testing included determination of mechanical characteristics (compressive and flexural strength) and durability aspects (sorption, evaporation, wet and dry cycle, resistance against salt, alkaline and acid solution). The test results exhibited that mechanical characteristics and resistance against wet and dry cycles improved when quarry dust completely replaced river sand as fine aggregate. When quarry dust content increased, the cubes subjected to severe environmental conditions exhibited higher strength reduction rates compared to that of normal environmental condition. The final strength, however was higher than the corresponding cubes with river sand. In addition to strength improvement, quarry dust replacement yielded lesser cost and sustainable benefits, which would promote the deployment of quarry dust in cement-sand block production.

Use of Micrografting to Study the Role Played by Peptide Signals in ABA Biosynthesis.

Plants survive by deploying appropriate stress responses under rapidly changing environmental conditions. Vascular plants transmit environmental information among distant organs. Long-distance signaling plays a crucial role in plant adaptation and subsequent survival under severe environmental conditions. In model plants, the micrografting method has recently emerged as an important method to elucidate tissue-to-tissue communication via hormones, RNAs, and peptides. In this chapter, I describe a micrografting method for Arabidopsis thaliana to graft shoots onto roots of plants with different genotypes. This grafting method may facilitate further research investigating how vascular plants integrate environmental information among distant organs via long-distance signaling.

The Effect of Cow Dung Ash as A Filler on The Mechanical Characteristics of Hot Mix Asphalt

Highway pavements are being exposed to increasing traffic loads and severe environmental conditions, resulting in reduced service life. A lot of studies have been conducted to modify asphalt by using different materials, especially to replace the ordinary filler. Because the behaviour of the hot asphalt mix is influenced by the fillers. The use of unusual materials as fillers in asphalt mixes can help to improve the mix’s characteristics. As a result, this study uses cow dung ash materials with various replacement ratios as fillers to investigate the mechanical properties of asphalt. In the asphalt mix, a replacement percentage of limestone (0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100%) was utilized. After that, various tests were performed such as Marshall stability, Marshall flow, voids in mineral aggregate, theoretical maximum specific gravity, air voids. The results revealed a significant improvement in the asphalt mix’s behaviour, as well as an increase in the replacement percentage. According to the findings, the 50% replacement rate has the highest Marshall stability which is equal to 11.11 with a 33.5% rise and the lowest flow of 3 with a 17.83% decrease when compared to the reference mix. As a result, cow dung ash can be used as a filler to modify the mechanical properties of the asphalt mix.

Integration of wind and tidal turbines using spar buoy floating foundations

<abstract> <p>Floating platforms are complex structures used in deep water and high wind speeds. However, a methodology should be defined to have a stable offshore structure and not fail dynamically in severe environmental conditions. This paper aims to provide a method for estimating failure load or ultimate load on the anchors of floating systems in integrating wind and tidal turbines in New Zealand. Using either wind or tidal turbines in areas with harsh water currents is not cost-effective. Also, tidal energy, as a predictable source of energy, can be an alternative for wind energy when cut-in speed is not enough to generate wind power. The most expensive component after the turbine is the foundation. Using the same foundation for wind and tidal turbines may reduce the cost of electricity. Different environment scenarios as load cases have been set up to test the proposed system's performance, capacity and efficiency. Available tidal records from the national institute of Water and Atmospheric Research (NIWA) have been used to find the region suitable for offshore energy generation and to conduct simulation model runs. Based on the scenarios, Terawhiti in Cook Strait with 110 m water height was found as the optimized site. It can be seen that the proposed floating hybrid system is stable in the presence of severe environmental conditions of wind and wave loadings in Cook Strait and gives a procedure for sizing suction caisson anchors.</p> </abstract>

In-service failure of a support structure for traffic signaling

Traffic signals and their supporting structures are an essential complement in highways and local roadways all around the world. Their accurate operation is today a well-recognized issue by the respective transportation authorities, especially when located on major roadways because of exposure to fatigue cracking by wind-induced large-amplitude vibrations and severe environmental conditions or wind gusts resulting from the passing trucks. The present paper describes the research undertaken to analyze the fatigue failure of a bolted joint in an overhead porticoed structure for traffic signaling located close to a highway entrance to a tunnel. The structure had been in use for more than 25 years and the failure was preventively detected, during a maintenance inspection. The research is a forensic engineering analysis of failure involving optical and scanning electron microscopy observations of the in-service fractured bolts together with the experimental characterization of the fatigue behavior of the bolt steel by means of non-standardized fatigue tests. The failure analysis pointed to the existence of environmentally-induced fatigue initiators as the failure origin, the galvanized condition of the bolts and environment aggressivity gave rise to local dissolution and microcracking of the Zn-coating, damaging and weakening specific zones at the steel interface that acted as fatigue initiators.

Mechanical properties and self-sensing ability of amorphous metallic fiber-reinforced concrete

The aim of this research work is to develop a corrosion resistant fiber-reinforced concrete for radioactive waste disposal structures. In the case of precast concrete, the use of fibers is a solution to reduce the amount of steel reinforcement while maintaining high mechanical performance and durability. Concrete has a low strain capacity and a limited tensile strength. Generally, reinforcing bars are used to ensure tensile strength. A fiber reinforcement can also help to overcome such a mechanical weakness. For this purpose, an amorphous metallic fiber (AMF), corrosion-resistant and suitable for application in severe environment conditions are used. The fresh and hardened properties of the self-compacting fiber reinforced concrete (SCFRC) are studied with volume fractions of AMF of 0% and 0.28% and with three different aspect ratios (82, 114 and 123). Flexural tensile tests according to European standard EN 14651 are conducted to quantify the contribution of the fiber reinforcement on the residual flexural tensile strength. Since these fibers are electrically conductive, they are also tested to design a smart concrete. For this purpose, electrical resistance of specimens submitted to cyclic flexural loadings are monitored using a Wheatstone bridge.

An Experimental Investigation on the Strength Properties of Ceramic Tiles Waste Powder based Bacterial Concrete

Concrete offers several benefits over steel, including availability, affordability, viscosity, compressive strength, and manufacturing simplicity. However, one notable drawback is that concrete has a lower tensile strength, which causes microcracks when subjected to persistent pressure and harsh weather conditions. The service life of a structure is mostly determined by its concrete strength; in other words, moderate environmental conditions may strengthen it, while severe environmental conditions may weaken it. The degradation of concrete materials is also induced by bio-corrosion produced by microorganisms that generate sulphuric acid to make sulphate. The source of durability and repair system issues is a lack of concrete supply. Bacterial uses in concrete rehabilitation, pore-clogging, and cracking have all been investigated. Bacillus species are tiny creatures that are gram-positive, spore-forming, oxygen-dependent, and have dormant, thick-walled cells. They may live for up to 200 years as spore-forming bacteria. According to an experimental investigation, the compressive strength of concrete is improved by using ceramic tile waste powder-based bacterial concrete. Bacillus megaterium is used in this experiment. This research looked at various concrete tests, including compressive strength, split tensile strength, and workability.

Understanding Pollution in China through the Lens of Environmental Justice

Environmental Justice is based on the principle that all people have a right to be protected from environmental pollution, and to live in and enjoy a clean and healthful environment, in which the essence of the theory is about the fair distribution of environmental benefits and responsibilities. Taking mass incidents in China from the 1990s to the beginning of the 21st century as examples, this paper illustrates that the lack of understanding and demonstration of three dimensions of environmental justice: distribution, political administration, and social recognition, has fundamentally led to severe environmental conditions in China, notably in the form of heavy environmental pollution. This paper suggests to highlight the "injustice" embedded in Chinese pollution issues, which usually hidden behind the common "excuse" of rapid urbanization and economic development, through establishing the concept of environmental justice, paying attention to economic and environmental policies and focusing on humanistic concerns.

Effective treatment of oily sludge for biogas and methane gas production at mesophilic using anaerobic batch reactor (AnBR)

The oily sludge is one of the toxic organic sludge generated from petroleum oil refineries plants and categorized as priority pollutants. Anaerobic batch treatment using bacteria species is a key strategy for treating toxic pollutants. The present study aims to produce biogas and methane gas at mesophilic conditions by using potential bacteria existing in oily sludge. The oily sludge was found rich in microorganisms adapted to extreme toxic organic waste and capable of adjusting to severe environmental conditions. The potential microorganism was isolated by enrichment technique to analyze the potential of the isolated strains to assimilate under lab scale. Anaerobic batch treatment at mesophilic temperature of ±35 °C, pH (6–8), 60 rpm mixing for 21 days with sample feed of 1L, 1.5L and 2L of oily sludge to produce biogas and methane gas by water displacement method. The results from anaerobic batch treatment shows that total biogas yield obtained, including methane yield of 25369 mL and 3900 mL, respectively at optimum feed volume of 2L. Overall, the study's findings revealed that oily sludge has the potential bacteria to produce the amount of biogas and methane gas. The large amount of oily sludge can be recycled, which will reduce environmental contamination. The investigations from the current study will help with the feasibility of oily sludge treatment in the future.

Analysis of the Ultrasonic Signal in Polymeric Contaminated Insulators Through Ensemble Learning Methods

Outdoor insulators may experience stress due to severe environmental conditions, such as pollution and contamination. Through the identification of partial discharges by ultrasonic noise, it is possible to assess the possibility of a power grid failure occurring. In this paper, ensemble models are used to analyze an ultrasonic signal from an ultrasonic microphone Pettersson M500. As the insulators are susceptible to developing irreversible failures, it will be evaluated whether the ultrasonic signal will remain over time, so that it is possible to assess whether the discharges being captured can result in a failure in contaminated polymeric insulators, evaluated in a high voltage laboratory under controlled conditions. The ensemble models were used in this paper because they typically require less computational effort than techniques based on deep learning and have acceptable performance for the problem at hand. The bagging, boosting, random subspace, bagging plus random subspace, and stacked generalization ensemble models are evaluated, and the best result of each model is used to compare the differences between the models. The bagging ensemble learning model proved to be faster and have lower error than other ensemble models, long short-term memory (LSTM), and nonlinear autoregressive (NAR).

Cleaner production of proso millet (Panicum miliaceum L.) in salt-stressed environment using re-watering: From leaf structural alleviations to multi-omics responses

Severe environmental conditions inhibit plant growth, which is rapidly restored when conditions improve. However, the mechanisms underlying re-watering to relieve Na+ toxicity and promote growth in proso millet are unclear. Herein, comparative phenotypic, physiological, phytohormone and multi-omics analyses between salt-sensitive (SSR) and salt-tolerant (STIM) proso millet cultivars were performed under salt stress and subsequent re-watering. Phenotypic and physiological analyses suggested that the accumulation of biomass and growth rate of STIM were not only higher after stress recovery than SSR but also higher than its control condition (STIM_CK), showing a compensation effect. A microstructural analysis indicated that STIM maintained a better surface structure, internal structure, and chloroplasts after stress recovery compared with its reactions under salt stress. A phytohormone analysis showed that the jasmonic acid (JA) and jasmyl-L-isoleucine (JA-Ile) contents specifically and significantly increased in STIM under salt stress and recovered with re-watering. Transcriptome analysis suggested that 3160 differentially expressed genes (DEGs) (1671 DEGs were downregulated, and 1589 DEGs were upregulated) and 1319 DEGs (565 DEGs were downregulated, and 751 DEGs were upregulated) were specifically identified in STIM under salt stress and re-watering, respectively, whereas 6184 DEGs (2666 DEGs were downregulated, and 3518 DEGs were upregulated) and 2721 DEGs (1175 DEGs were downregulated, and 1546 DEGs were upregulated) were detected in SSR. Proteomes analyses showed that up to 38.28% and 44.68% of proteins were individually expressed specifically at the protein level in SSR under salt stress and subsequent re-watering, respectively, and 43.56% and 39.31% in STIM, respectively, indicating the involvement of posttranscriptional regulation under salt stress and subsequent re-watering. Subsequently, the functions of commonly regulated DEGs and differentially expressed proteins (DEPs) were analyzed, which were significantly enriched in photosynthesis and porphyrin and chlorophyll metabolism pathways. Therefore, this study provides guidelines for phytoremediation and utilization of saline soils, and cleaner crop production.

Resistance to severe environmental conditions of prototypical recycling-based under ballast mats (UBMs) used as vibration isolators in the ballasted track systems

The present paper focuses on laboratory tests of resistance to severe environmental conditions performed on prototypical under ballast mats (UBMs) according to the procedure described in the European standard EN 17282, which was introduced at the end of 2020. Most of the analyzed samples of UBMs were based on elastomeric materials from recycling, such as styrene butadiene rubber (SBR) granulate and fibers from recycled waste tires and rebond polyurethane from polyurethane waste, and additionally, for comparative reasons, one of the tested UBM samples was based on mineral wool. It was proved that in the case of mineral wool- and polyurethane-based samples, there are significant differences in static and dynamic characteristics determined before and after the resistance tests and permanent deformations are observed. Elastomeric mats based on recycled rubber exhibited good properties in the performed tests and thus, they should be regarded as effective and durable vibration isolators which can be used to protect people and the surrounding environment against structure-borne noise and vibration generated by railway traffic. The results of experimental tests were additionally used by the authors to create a viscoelastic model of the vibration isolator (UBM) with fractional derivatives. Using the original model of the ballasted track structure with four degrees of freedom, a significant influence of severe environmental conditions together with the dynamic cyclic loading on the level of vibration suppression (insertion loss factor) was demonstrated. Additionally, the authors proposed the assessment criteria for the resistance to severe environmental conditions of UBMs, tested according to the new standard EN 17282.

Effect of Heating Duration at High Temperature on the Strength and Integrity of Fly Ash-Based Geopolymer Concrete

Fire is one of the most severe environmental conditions that concrete structures might be subjected to, especially in closed conduct structures, such as tunnels. Concrete in general can withstand fire but its properties degrade when exposed to fire at high temperatures. The effect of heating duration, at a high temperature, on the performance of fly ash-based geopolymer concrete is presented. Cubes of low, medium and high strength grades of geopolymer concrete that had been cured for 28 days, were exposed to a fire flame at 1000 °C for 30, 60, 90, 120, 150 and 180 min. After the fire exposure, the cubes were cooled to the ambient temperature before further testing. A visual observation was performed on the cubes to detect any colour change, cracking and spalling. The losses of mass and residual compressive strength of the cubes were recorded. The results showed that as the heating duration increased from 30 to 90 min, the compressive strength of the cubes also increased. Contrarily, the compressive strength decreased as the heating duration increased beyond 90 min indicating that the extended heating duration induced the loss of free water and decomposition of aluminosilicate products in geopolymer concrete. The evaporation of water by virtue of the heating for the extended duration, at high temperature, led to a loss in the mass of concrete. The findings suggest that geopolymer concrete was able to sustain its structural integrity without any noticeable spalling and hence, it can be classified as a fire-resistant material.

System Modeling and Risk Analysis of the Sichuan–Tibet Railway Project

AbstractThe severe geological and environmental conditions along the Sichuan–Tibet railway easily lead to unfavorable events that place construction safety at risk. To comprehensively identify the ...