Mining threats in high-level biodiversity conservation policies

Amid a global infrastructure boom, there is increasing recognition of the ecological impacts of the extraction and consumption of construction minerals, mainly processed as concrete, including significant and expanding threats to global biodiversity. We investigated how high-level national and international biodiversity conservation policies address mining threats, with a special focus on construction minerals. We conducted a review and quantified the degree to which threats from mining these minerals are addressed in biodiversity goals and targets under the 2011-2020 and post-2020 biodiversity strategies, national biodiversity strategies and action plans, and the assessments of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Mining appeared rarely in national targets but more frequently in national strategies. Yet, in most countries, it was superficially addressed. Coverage of aggregates mining was greater than coverage of limestone mining. We outline 8 key components, tailored for a wide range of actors, to effectively mainstream biodiversity conservation into the extractive, infrastructure, and construction sectors. Actions include improving reporting and monitoring systems, enhancing the evidence base around mining impacts on biodiversity, and modifying the behavior of financial agents and businesses. Implementing these measures could pave the way for a more sustainable approach to construction mineral use and safeguard biodiversity.

Knowledge and regulation on fungal contamination of sand and water: Progress report and perspectives

Fungal flora in coastal/inland beach sand and recreational water is a neglected field of study, despite its potential impact on human health. A joint International Society for Human and Animal Mycology/European Confederation for Medical Mycology (ISHAM/ECMM) working group was formed in 2019 with the task to set up a vast international initiative aimed at studying the fungal contamination of beaches and bathing waters. Here we review the importance of the topic, and list the main results and achievements from 12 scientific publications. Fungal contamination exists at different levels, and the genera most frequently found were Aspergillus spp., Candida spp., Fusarium spp., and Cryptococcus spp., both in sand and in water. A site-blind median was found to be 89 colony-forming units of fungi per gram of sand in coastal/inland freshwaters. This threshold has been used for the sand quality criterion of the blue flag in Portugal. Additionally, our data were considered pivotal and therefore used for the first inclusion of fungi as a biological taxon of interest in water quality and sand monitoring recommendations of the World Health Organization's new guidelines on recreational water quality (Vol.1-Chap7). The findings of the consortium also suggest how environmental conditions (climate, salinity, soil pH, nitrogen, etc.) influence microbial communities in different regions, and that yeast species like Candida glabrata, Clavispora lusitaniae, and Meyerozyma guilliermondii have been identified as potential fungal indicators of fecal contamination. Climate change and natural disasters may affect fungal populations in different environments, and because this is still a field of study under exploration, we also propose to depict the future challenges of research and unmet needs.

Seasonal Variation in Fungi in Beach Sand in Summertime: Stintino (Italy)

BACKGROUND

The goal of this study was to monitor the microbial biodiversity in beach sand that is heavily visited by tourists during the summer, and to determinate whether the high presence of bathers (around 5000 per day) can modify sand microbial composition.

METHODS

Between 2016 and 2020, 150 sand samples were collected from nine different points at La Pelosa beach in Sardinia, Italy. Non-culturing methods were used; DNA extraction and meta-barcode sequencing were performed. All samples were analyzed with sequencing methods for 16S and ITS sequences.

RESULTS

Fungal genera differ on the three beaches and in the winter/summer zones. The ITS sequence showed the most common presence of Candida during summer and Paradendryphiella in the winter. The greatest diversity was found in the dune during winter, while in other parts of the beach, there are differences between bacteria and fungi, particularly in the wash zone during the winter, with high diversity for 16S sequences but low diversity for ITS sequences.

CONCLUSIONS

It appears reasonable that the sands, even on non-urban beaches, should be included in health monitoring programs in addition to the waters, and that access to them should be regulated by limiting the number of bathers with the aim of reducing the presence of pathogenic fungal species.

Anisotropy in the Liquefaction Resistance of Fibre Reinforced Sand

Adding discrete fibres to sand has been seen as a feasible technique to improve sand's strength as well as liquefaction resistance. Considering the anisotropic distribution of fibre orientations, the anisotropy in the liquefaction resistance of the reinforced sand is also introduced using fibres. Here, the triaxial compression and extension test results of unreinforced and fibre-reinforced sand in different density states are provided, from which the anisotropy in the liquefaction resistance of fibre-reinforced sand is demonstrated. Fibre reinforcement improves the liquefaction resistance of sand by introducing both the densifying effect and the confining effect. The inclusion of fibres increases both the slope and the intercept of the strength envelope in comparison with the unreinforced sand under triaxial compression, while the strength envelope is not affected by fibres under triaxial extension. Stress contribution of fibres makes the ESP of the composite under undrained loading reverse its direction to develop even though the phase transformation is absent. The stress ratio initiating the ESP reversal is irrespective of the fibre content but dependent on the density state under triaxial compression. Under triaxial extension, the stress ratio initiating the ESP reversal remains the same in the samples with varied density states and fibre contents. The mechanism correlating to the strength envelope and ESP reversal of the fibre-reinforced sand was demonstrated following a rule of mixture based constitutive modelling framework. By introducing an alternatively defined pore pressure ratio that incorporates the stress contribution of fibres, the liquefaction state of the fibre reinforced sand is reasonably assessed. Liquefaction remains absent in the sand once the fibres are mixed. The anisotropy in the liquefaction resistance of fibre-reinforced sand arises, as the predominant role played by the fibres to suppress the liquefaction is different when varied loading paths are involved, which is sourced from the anisotropic distribution of fibre orientations.

Predicting the Temperature-Dependent Long-Term Creep Mechanical Response of Silica Sand-Textured Geomembrane Interfaces Based on Physical Tests and Machine Learning Techniques

Preciously assessing the creep mechanical response of sand-geomembrane interfaces is vital for the design of relevant engineering applications, which is inevitable to be influenced by temperature and stress statuses. In this paper, based on the self-developed temperature-controlled large interface shear apparatus, a series of long-term creep shear tests on textured geomembrane-silica sand interfaces in different temperatures, normal pressure, and creep shear pressure were conducted, and a database compiled from the physical creep shear test results is constructed. By adopting the database, three disparate machine learning algorithms of the Back Propagation Artificial Neural Network (BPANN), the Support Vector Machine (SVM) and the Extreme Learning Machine (ELM) were adopted to assess the long-term creep mechanical properties of sand-geomembrane interfaces while also considering the influence of temperature. Then, the forecasting results of the different algorithms was compared and analyzed. Furthermore, by using the optimal machine learning model, sensitivity analysis was carried out. The research indicated that the BPANN model has the best forecasting performance according to the statistics criteria of the Root-Mean-Square Error, the Correlation Coefficient, Wilmot's Index of Agreement, and the Mean Absolute Percentage Error among the developed models. Temperature is the most important influence factor on the creep interface mechanical properties, followed with time. The research findings can support the operating safety of the related engineering facilities installed with the geomembrane.

Applications of Recycled and Crushed Glass (RCG) as a Substitute for Natural Materials in Various Fields-A Review

Glass is a substance that is present in most houses since glass-based items are made and consumed in relatively high quantities. This has led to the buildup of glass in concerning quantities all over the world, which is a problem for the environment. It is well known that glass has several advantageous physiochemical features that qualify it as an appropriate material for use in the construction industry as an aggregate. The features include being non-biodegradable, resistant to chemical assault, having low water absorption, having high hydraulic conductivity, having temperature-dependent ductility, having alterable particle gradation, and having a wide availability in a variety of forms and chemical compositions. Because of these qualities, glass has been used in various investigations and field tests conducted in civil engineering to evaluate its effectiveness as an engineering aggregate and to develop environmentally friendly management strategies for waste glass. These studies and research have utilized glass in various forms, such as fine recycled glass, medium recycled glass, coarse recycled glass, powdered glass, and glass-based geopolymers. This study focuses on research studies that present results on physicochemical, mechanical, and durability characteristics. These studies and research contain samples of pure glass or glass as replacement percentages in materials (0-100%), including but not limited to unbound granular materials (such as recycled concrete aggregates and crushed rock). In light of the information assembled in this review article, it is legitimate to claim that glass has strong promise as a material in various civil applications.

Weakly Cross-Linked Anionic Copolymers: Kinetics of Swelling and Water-Retaining Properties of Hydrogels

Six cross-linked copolymers consisting of sodium acrylate, N-acrylamide, starch fragments and a cross-linker were synthesized, potentially suitable for use in agriculture as superabsorbents. The copolymers had the same content of carboxyl groups equal to 6.2 mmoles per 1 g of copolymer and the content of cross-linker (Q) varied from 0.04 up to 1 wt.%. The copolymers swelled in a pH 6.5 aqueous buffer solution thus giving hydrogel particles, which were characterized by a set of methods including gravimetry, rheometry, swelling pressure analysis, equilibrium centrifugation and water retention analysis with the following main conclusions. An increase in Q decreases the equilibrium degree of swelling. When swelling in a solid substrate, sand or soil, the equilibrium degree of swelling shows the maximum at Q = 0.14 wt.%. The cross-linking degree controls the swelling pressure of hydrogels and water-retaining properties of solid substrates with embedded hydrogels; in both cases, the maximum effects are observed at Q = 0.14 wt.%. These extreme dependences set the algorithm for synthesis of polymeric superabsorbents and optimization of their operational characteristics.

Hungarian Fine-to-Coarse Aggregate, a Possible Constituent of Near-Vessel Structural Concrete of Nuclear Power Plants

Significant gravel mines, representative of four regions of Hungary (northeast, central, northwest, and southwest) were systematically sampled to characterize their sand and pebbles as potential constituents of nuclear-grade concrete. The samples were analysed for their elemental compositions as a function of the mining locality and grain size, using two complementary neutron-based analytical techniques, prompt gamma activation analysis (PGAA) and neutron activation analysis (NAA). The combined analysis resulted in reliable mass fractions for over thirty elements that could be used to assess the radiation shielding and activation properties of the resulting concrete, essential in nuclear applications, by means of computer simulations. The studied aggregates are proven to be appropriate constituents for biological shielding at radiological centres, NPPs, and at nuclear research installations, even in mixed neutron/gamma radiation fields. The elemental compositions also revealed geochemical differences between the sedimentologically different regions.

Strategies for Monitoring Microbial Life in Beach Sand for Protection of Public Health

The 2021 revised guidelines of the World Health Organization recommend monitoring the quality of sand in addition to water at recreational beaches. This review provides background information about the types of beaches, the characteristics of sand, and the microbiological parameters that should be measured. Analytical approaches are described for quantifying fungi and fecal indicator bacteria from beach sand. The review addresses strategies to assess beach sand quality, monitoring approaches, sand remediation, and the proposed way forward for beach sand monitoring programs. In the proposed way forward, recommendations are provided for acceptable levels of fungi given their distribution in the environment. Additional recommendations include evaluating FIB distributions at beaches globally to assess acceptable ranges of FIB levels, similar to those proposed for fungi.

A Novel Approach of Optimum Time Interval Estimation for Al-7.5Si/Al-18Si Liquid-Liquid Bimetal Casting in Sand and Metallic Moulds

This work describes a novel approach for Al-7.5Si/Al-18Si liquid-liquid bimetal casting in sand and metallic moulds. The aim of the work is to facilitate and develop a simple procedure to produce an Al-7.5Si/Al-18Si bimetallic material with a smooth gradient interface structure. The procedure involves the theoretical calculation of total solidification time (TST) of the first liquid metal (M1), pouring the liquid metal (M1), and allowing it to solidify; then, before complete solidification, the second liquid metal (M2) is introduced into the mould. This novel approach has been proven to produce Al-7.5Si/Al-18Si bimetal materials using liquid-liquid casting. The optimum time interval of Al-7.5Si/Al-18Si bimetal casting with modulus of cast M_c ≤ 1 was estimated based on subtracting 5-15 s or 1-5 s from TST of M1 for sand and metallic moulds, respectively. Future work will involve determining the appropriate time interval range for castings having modulus ≥ 1 using the current approach.

Removal of Methylene Blue from Aqueous Solution by Mixture of Reused Silica Gel Desiccant and Natural Sand or Eggshell Waste

The purpose of this work was to develop, characterize and test new low-cost materials suitable for removing methylene blue dye from water and wastewater by adsorption. The solid materials consisted of silica gel powder (SG), silica gel mixed with eggshell powder (SG-ES) and a mixture of silica gel with sand from the western Iraqi desert (SG-SI). The samples were milled by using an electrical mixer and a ball mill, followed by a drying step. In addition, desert sand was acid-treated in order to remove impurities. The structure and chemical composition of the samples were investigated by X-ray diffraction (XRD), a scanning electron microscopy technique equipped with an energy-dispersive X-ray spectrometer (SEM-EDX), a low-temperature nitrogen adsorption (BET) technique, thermo-analytical (TG/TGA) measurements and Fourier-transformed infrared spectroscopy (FTIR). The previously mentioned materials were tested to remove methylene blue from an aqueous solution. The adsorption experiments were monitored by ultraviolet-visible (UV-Vis) spectrophotometry and showed that SG and SG-ES gave promising results for the methylene blue removal from water. After 40 min of treatment of the aqueous solution containing 10 mg/L of MB at room temperature, the tested SG, SG-ES and SG-SI materials were found to have 86%, 80% and 57% dye adsorption efficiency, respectively. Taking into consideration not only the adsorption activity of the studied material but their availability, cost and concepts of cleaner production and waste minimization, the developed silica gel with eggshell can be considered as a good, cost-effective alternative to commercially available activated-carbon-based adsorbents. Different kinetic and isotherm models were fitted to the experimental results. A pseudo-second-kinetics-order model revealed high correlation fitting, while the Freundlich model was found to appropriately describe the adsorption isotherm. The thermal stability during the possible regeneration process of the SG-ES adsorbent mixture and its interaction mechanism with cationic dye was discussed.

Genetic Determinants of Escherichia coli Survival in Beach Sand

Escherichia coli contain a high level of genetic diversity and are generally associated with the guts of warm-blooded animals but have also been isolated from secondary habitats outside hosts. We used E. coli isolates from previous in situ microcosm experiments conducted under actual beach conditions and performed population-level genomic analysis to identify accessory genes associated with survival within the beach sand environment. E. coli strains capable of surviving had been selected for by seeding isolates originating from sand, sewage, and gull waste (n = 528; 176 from each source) into sand, which was sealed in microcosm chambers and buried for 45 days in the backshore beach of Lake Michigan. In the current work, survival-associated genes were identified by comparing the pangenome of viable E. coli populations at the end of the microcosm experiment with the original isolate collection and identifying loci enriched in the out put samples. We found that environmental survival was associated with a wide variety of genetic factors, with the majority corresponding to metabolism enzymes and transport proteins. Of the 414 unique functions identified, most were present across E. coli phylogroups, except B2 which is often associated with human pathogens. Gene modules that were enriched in surviving populations included a betaine biosynthesis pathway, which produces an osmoprotectant, and the GABA (gamma-aminobutyrate) biosynthesis pathway, which aids in pH homeostasis and nutrient use versatility. Overall, these results demonstrate that the genetic flexibility within this species allows for survival in the environment for extended periods. IMPORTANCE Escherichia coli is commonly used as an indicator of recent fecal pollution in recreational water despite its known ability to survive in secondary environments, such as beach sand. These long-term survivors from sand reservoirs can be introduced into the water column through wave action or runoff during precipitation events, thereby impacting the perception of local water quality. Current beach monitoring methods cannot differentiate long-term environmental survivors from E. coli derived from recent fecal input, resulting in inaccurate monitoring results and unnecessary beach closures. This work identified the genetic factors that are associated with long-term survivors, providing insight into the mechanistic basis for E. coli accumulation in beach sand. A greater understanding of the intrinsic ability of E. coli to survive long-term and conditions that promote such survival will provide evidence of the limitations of beach water quality assessments using this indicator.

Stress-Dilatancy Behaviourof Fibre-Reinforced Sand

This paper analyses the stress-strain behaviour of fibre-reinforced sand using the results obtained by drained triaxial compression tests presented in the literature. The general stress-plastic dilatancy equation of the Frictional State Concept has been used to describe the behaviour of fibre-reinforced sand for different shear phases. The behaviour of pure sand is taken as a reference for the behaviour of sand with added fibres. It is shown that the characteristic shear phases can only be determined when the η-Dp relationships are used, which are very rarely demonstrated in the results of shear tests presented in the literature. It has been shown that tensile strains must occur in order to achieve the strengthening effect of fibre reinforcement. A reduction in the stiffness of the fibre-sand composite is observed in the absence of tensile strains below certain threshold values.

Colonic sand impaction with cecal rupture and peritonitis in an adult African savanna elephant, and review of noninfectious causes of gastrointestinal disease in elephants

Gastrointestinal disorders are among the most common disease processes in captive elephants. Colic is a frequent clinical presentation and may have several infectious and noninfectious causes. Ingestion of sand has been reported in elephants living in enclosures with loose sandy soils. Similar to the situation in horses, sand ingestion can cause intestinal impaction and colic in elephants. Here we describe a case of colonic sand impaction with cecal rupture and peritonitis in an African savanna elephant from a zoologic collection that died after several days of colic. On autopsy, abundant, gritty, sandy material was found within a segment of colon immediately aboral to the cecum. There was a full-thickness tear in the cecal wall, free intestinal contents within the abdominal cavity, and peritonitis. To our knowledge, the postmortem examination of an elephant with sand impaction and cecal rupture has not been reported previously; this condition should be included among the differential diagnoses in elephants with colic. We review the reports of noninfectious causes of gastrointestinal disease in elephants, which include cases of small intestinal and colonic torsion and of intestinal obstruction by fecal boluses.

Caspian Sea Mycosands: The Variety and Abundance of Medically Important Fungi in Beach Sand and Water

Samples from a total of 67 stations, distributed amongst 32 cities along the Caspian Sea coastline, were collected during the summer of 2021 on sunny days. The samples were collected from each station, including both dry/wet sand and shoreline water. The grown samples were primarily analyzed for the macro/microscopic morphologic features of the fungi. Moreover, identification by PCR-RFLP was performed for yeasts, dermatophytes, and Aspergillus sp. strains. Antifungal susceptibility tests were performed for probable-isolated Aspergillus and Candida sp. A total of 268 samples were collected, from which 181 (67.54%) isolates were recovered. Yeast-like fungi and potential pathogenic black fungi were detected in 12 (6.6%) and 20 (11%) of the sand (dry/wet) samples. Potential pathogenic hyaline fungi were identified in 136 (75.1%) samples, in which Aspergillus sp. was the predominant genus and was detected in 76/136 (47.8%) samples as follows: A. section Flavi n = 44/76 (57.9%), A. section Nigri n = 19/76 (25%), A. section Nidulantes n = 9/76 (11.8%), and A. section Fumigati n = 4/76 (5.3%). The most effective azole antifungal agent was different per section: in A. section Fumigati, PSZ; in Aspergillus section Nigri, ITZ and ISZ; in A. section Flavi, EFZ; and in A. section Nidulantes, ISZ. Candida isolates were susceptible to the antifungals tested.

Effect and mechanism of the improvement of coastal silt soil by application of organic fertilizer and gravel combined with Sesbania cannabina cultivation

Jiangsu Province of China has a large area of coastal silt soil (CSS) with poor permeability, high salinity, and poor nutrients, which brings great difficulties to the development and utilization of coastal zones, so that needs to be improved as a matter of urgency. In this study, river-sand, serpentine, and organic fertilizer were used as additives in CSS, and Sesbania cannabina, a salt-tolerant cash crop, was planted in these differently treated soils. Through high-throughput sequencing, analysis of soil physico-chemical properties, and detection of plant growth status, the rhizosphere bacterial diversity of S. cannabina growing in CSS under different treatments and their environmental impact factors were studied, while exploring the effect and mechanism of organic fertilizer combined with gravel as a CSS modifier. The results implied that single application of organic fertilizer could significantly increase the fertility levels of total nitrogen (TN), total organic carbon (TOC) and Avail. P in CSS; then, the application of organic fertilizer with river-sand significantly reduced salt content and alkalinity of soil; meanwhile, in the treatment of single application of organic fertilizer and application of organic fertilizer combined with river-sand, the rhizosphere of S. cannabina enriched the bacterial communities of organic matter degradation and utilization to varying degrees. The soil moisture content and indicators related to saline-alkali soil (including total salt, electrical conductivity (EC), exchangeable sodium percentage (ESP), Avail. Na and Avail. K, etc.) were further reduced significantly by the application of organic fertilizer combined with river-sand and serpentine. The method has greatly improved the growth conditions of S. cannabina and promoted the positive development of its rhizosphere bacterial community. Among them, in the treatment of organic fertilizer combined with river-sand and serpentine, a variety of plant growth-promoting rhizobacteria (PGPR, such as Sphingomonas, Ensifer, and Rhodobacter) and nitrogen-cycle-related bacteria (such as nitrate-reduction-related bacteria, nitrogen-fixing bacteria like Ensifer, and purple non-sulfur photosynthetic bacteria like Rhodobacter) were enriched in the rhizosphere of S. cannabina; moreover, the mutual association and robustness of bacterial co-occurrence networks have been significantly enhanced. The results provide a theoretical basis and reference model for the improvement of coastal saline-alkali silt soil.

Progress of Polymer Application in Coated Proppant and Ultra-Low Density Proppant

Design, synthesis and application of low-density proppant (LDP) are of great significance for efficient and clean exploitation of low permeability oil and gas. On the basis of a brief introduction of hydraulic fracturing and the application of traditional proppants, this review systematically summarized the polymer application progress in LDP, including coated sand, coated ceramics, coated nutshells, especially for polymer composites based ultra-low density proppant (ULDP). Finally, the existing problems and future development direction are also prospected.

Biodegradable Interpolycomplexes for Anti-Erosion Stabilization of Soil and Sand

A linear anionic polysaccharide, sodium alginate, electrostatically interacts with a cationic polysaccharide, quaternized hydroxyethyl cellulose ethoxylate, in aqueous solution, thus giving an interpolyelectrolyte complex. Aqueous solutions of the initial polysaccharides and polycomplexes with an excess of the cationic or anionic polymers were used for the stabilization of soil and sand against water erosion. Physicochemical, mechanical and biological properties of the polymers and coatings were characterized by gravimetric analysis, viscosimetry, mechanical strength assessment, cell viability, and cell-mediated degradation with the following main conclusions. (a) Non-stoichiometric polycomplexes with an excess of cationic or anionic units ("cationic" and "anionic" polycomplexes, respectively) form transparent solutions or stable-in-time dispersions. (b) The complexation results in a decrease in the viscosity of polymer solutions. (c) A complete dissociation of polycomplexes to the initial components is achieved in a 0.2 M NaCl solution. (d) Soil/sand treatment with 1 wt% aqueous solutions of polymers or polycomplexes and further drying lead to the formation of strong composite coatings from polymer(s) and soil/sand particles. (e) Cationic polycomplexes form stronger coatings in comparison with anionic polycomplexes. (f) The polymer-soil coatings are stable towards re-watering, while the polymer-sand coatings show a much lower resistance to water. (g) The individual polysaccharides demonstrate a negligible toxicity to Gram-negative and Gram-positive bacteria and yeast. (h) The addition of Bacillus subtilis culture initiates the degradation of the polysaccharides and polycomplexes. (i) Films from polysaccharides and polycomplexes decompose down to small fragments after being in soil for 6 weeks. The results of the work are of importance for constructing water-resistant, low toxicity and biodegradable protective coatings for soil and sand.

Application of the Computed Tomography Method for the Evaluation of Porosity of Autoclaved Materials

This article describes the use of recycled glass sand in the production of autoclaved products. Traditional autoclaved bricks consist of crystalline sand, lime and water. The conducted research aimed at the complete elimination of quartz sand in favor of glass sand. This work focuses on porosity as the functional property of the materials. The aim of this article is to determine the number and structure of the pores of autoclaved bricks. Two types of research were carried out: (a) non-destructive, i.e., computed tomography examination as a pictorial and quantitative method and (b) mercury porosimetry as a quantitative method, i.e., a test that exposes the porous skeleton of the material for destruction. The tests showed the presence of pores with a size in the range of 0.1 ÷ 100 μm, and the volume of voids in the material was determined at the level of about 20% for the sample modified with glass sand (GS) and for the reference sample made of traditional silicate brick. In order to complete the research on the internal structure of autoclaved bricks, microstructure studies were performed using a scanning electron microscope (SEM). The tests showed the presence of tobermorite in the reference sample (with 90% QS-quartz sand) and the presence of natrolite and gyrolite in the sample modified by glass sand (90% GS).

A Critical Review on the Feasibility of Synthetic Polymers Inclusion in Enhancing the Geotechnical Behavior of Soils

Polymers have attracted widespread interest as soil stabilizers and are proposed as an ecologically acceptable means for enhancing the geotechnical properties of soils. They have found profound applications in diverse fields such as the food industry, textile, medicine, agriculture, construction, and many more. Various polymers are proven to increase soil shear strength, improve volume stability, promote water retention, and prevent erosion, at extremely low concentrations within soils through the formation of a polymer membrane around the soil particles upon hydration. The purpose of this work is to provide an overview of existing research on synthetic polymers for soil improvement. A fundamental evaluation of many synthetic polymers used in soil stabilization is provided, Furthermore, the impact of different polymer types on the geotechnical parameters of treated soil was assessed and compared. Limiting factors like polymer durability and the effect of changing climatic conditions on the engineering behavior of the polymer-treated soils have been critically reviewed. The dominant mechanisms responsible for the alteration in the behavior of polymer-soil admixture are reviewed and discussed. This review article will allow practicing engineers to better understand the intrinsic and extrinsic parameters of targeted polymers before employing them in real-field scenarios for better long-term performance.

Impact of Micro Silica Filler Particle Size on Mechanical Properties of Polymeric Based Composite Material

In this study, silica in the form of raw local natural sand was added to high-density-polyethylene (HDPE) in order to develop a composite material in the form of sheets that could have potential applications in thin film industries, such as packaging, or recycling industries, such as in 3D printing. The silica/HDPE composite sheets were developed using a melt extruder followed by using a hot press for compression molding. The impact of two different particle sizes (25 µm and 5 µm) of the silica particles on selected properties such as toughness, elastic modulus, ductility, and composite density were analyzed. A considerable increase in the toughness and elastic modulus was observed from 0 wt% to 20 wt% with a 25 µm filler size. However, a general decreasing trend was observed in the material's toughness and elastic modulus with decreasing particle size. A similar trend was observed for the ductility and the tensile strength of the sheets prepared from both filler particle sizes. In terms of the composite density, as the filler was increased from 20 wt% to 50 wt%, an increase in the composite densities was noticed for both particle sizes. Additionally, the sheets developed with 25 µm particle size had a slightly higher density than the 5 µm particle size, which is expected as the size can account for the higher weight. Results from this work aim to analyze the use of local sand as a filler material that can contribute towards maximizing the potential of such composite materials developed in extrusion industries.

Influence of Nutrients and the Native Community on E. coli Survival in the Beach Environment

Previous research has identified E. coli populations that persist in freshwater beach sand distinct from fecal pollution events. This work identifies factors that influence the survival of E. coli in sand using laboratory microcosms to replicate beach conditions. Microcosms were deployed to examine the effect of genetic background, competition with native microbial community, and increased nutrient concentrations on E. coli survival. Survival was comparable between the phylotypes B1 and B2, however, deficiency of stress response greatly reduced survival. In the absence of the native community under nutrient conditions comparable to those observed in sand, E. coli cell densities remained within an order of magnitude of initial concentrations after 5 weeks of incubation. Increased nitrogen was associated with decreased decay rates in the first 2 weeks, and increased carbon appeared to provide an advantage at later time points. However, the highest survival was found with the addition of both carbon and nitrogen. Native sand seeded with fresh Cladophora maintained higher concentrations of E. coli, compared to sand containing decayed Cladophora or no Cladophora. Our findings demonstrate persistent E. coli populations in sand can be affected by the availability of carbon and nitrogen, the ability to regulate stress, and the presence of algal mats (i.e., Cladophora). Further, this work suggests that the native microbial communities may modulate survival by outcompeting E. coli for nutrients. IMPORTANCE Current monitoring for fecal pollution does not account for persistent E. coli populations in freshwater sand, which can result in higher concentrations in water when no threat to human health is present. This work examined the drivers for persistent E. coli populations in sand to aid beach management techniques. We examined the influence of nutrients, including localized sources such as stranded Cladophora, on E. coli populations. We found the major determinant of E. coli survival in freshwater beach sand was the addition of nutrients, specifically carbon and nitrogen concentrations 10-fold higher than baseline concentrations on beaches. This work provides the framework for identifying pollution sources that can promote E. coli survival in sand through the characterization of carbon and nitrogen content, which can be incorporated into beach management techniques. Through this improved knowledge, we can begin to understand E. coli fluctuations in water due to resuspension from sand into water.

Experimental Investigation of Sand Subjected to High Stress Levels in Wet and Dry Conditions

This work aimed to understand the mechanical behavior of siliceous and calcareous sand materials under uniaxial confined compression loading at high stress levels. For this purpose, a series of quasi-oedometric compression tests were conducted on sand materials, to examine the effects of grain size, nature, and moisture contents on the soil crushability and the compression behavior, using an upgraded thick pressure vessel device that can reach mean stress up to 500 MPa. All samples were prepared using an aspect ratio of 1:1 (diameter: height), placed inside a high strength steel vessel, and compressed at a uniform axial displacement rate of 5 µm/s. The vessel is instrumented with multiple strain gauges allowing for the characterization of the hydrostatic and deviatoric behavior of each test. The results of quasi-oedometric tests, conducted on these types of sand, up to a passive confinement of 500 MPa, show that particle breakage is enhanced by the presence of water. It was noticed that, for siliceous sand, smaller particles break more than larger particles, and that the calcareous grains manifest a rapid response to axial stress compared to siliceous sand. Testing various soil properties shows a great potential to better characterize the sensitivity to breakage of soils. Lastly, a post-mortem analysis of samples before and after testing, using the X-ray micro-tomography technique, was applied to study the mechanical damage of sand specimens.

Performance Prediction of Erosive Wear of Steel for Two-Phase Flow in an Inverse U-Bend

Erosion of the elbow due to non-Newtonian viscous slurry flows is often observed in hydrocarbon transportation pipelines. This paper intends to study the erosion behavior of double offset U-bends and 180° U-bends for two-phase (liquid-sand) flow. A numerical simulation was conducted using the Discrete Phase Model (DPM) on carbon steel pipe bends with a 40 mm diameter and an R/D ratio of 1.5. The validity of the erosion model has been established by comparing it with the results quantified in the literature by experiment. While the maximum erosive wear rates of all evaluated cases were found to be quite different, the maximum erosion locations have been identified between 150° and 180° downstream at the outer curvature. It was seen that with the increase in disperse phase diameter, the erosive wear rate and impact area increased. Moreover, with the change of configuration from a 180° U-bend to a double offset U-bend, the influence of turbulence on the transit of the disperse phase decreases as the flow approaches downstream and results in less erosive wear in a double offset U-bend. Furthermore, the simulation results manifest that the erosive wear increases with an increase in flow velocity, and the erosion rate of the double offset U-bend was nearly 8.58 times less than the 180° U-bend for a carrier fluid velocity of 2 m/s and 1.82 times less for 4 m/s carrier fluid velocity. The erosion rate of the double offset U-bend was reduced by 120% compared to the 180° U-bend for 6 m/s in liquid-solid flow.

Reduced Vastus Medialis/Lateralis EMG Ratio in Volleyballers with Chronic Knee Pain on Sports-Specific Surfaces: A Pilot Study

BACKGROUND

Even though chronic knee pain is common in volleyball, neuromuscular imbalance as a potential risk factor has not been investigated in volleyball-specific tasks. The aim of the study was to compare neuromuscular control between healthy and injured players in a clinical jump test and a volleyball-specific jump task in real field conditions.

METHODS

Six athletes with knee pain and nine controls were included. Surface electromyographic data were recorded from the mm. vastus medialis (VM) and lateralis (VL) of both legs. VM/VL activation ratio was calculated from countermovement jump (CMJ) and volleyball spike indoors and on two beach surfaces.

RESULTS

All subjects had pain in the leading leg. Mann-Whitney U Test (M-W-U Test) revealed a significantly lower VM/VL ratio of the leading leg (always affected) of the injured compared with that of the healthy control group for the CMJ and spike jump on all three grounds. Bland-Altman analysis revealed low bias and low difference in standard deviation for the injured leg but high values for the uninvolved leg and healthy controls between tasks and grounds. These results could indicate that neuromuscular control might not adapt too well to different movement tasks and grounds in the injured leg.

CONCLUSION

Athletes with chronic knee pain might have lower VM/VL ratios than controls independent from movement task and ground. Neuromuscular control in injured athletes might be less adaptable to new circumstances. The results of neuromuscular control in laboratory settings might be applicable to field conditions in injured legs but not healthy ones.

Influence of Elbow Angle on Erosion-Corrosion of 1018 Steel for Gas-Liquid-Solid Three Phase Flow

Erosive wear due to the fact of sand severely affects hydrocarbon production industries and, consequently, various sectors of the mineral processing industry. In this study, the effect of the elbow geometrical configuration on the erosive wear of carbon steel for silt–water–air flow conditions were investigated using material loss analysis, surface roughness analysis, and microscopic imaging technique. Experiments were performed under the plug flow conditions in a closed flow loop at standard atmospheric pressure. Water and air plug flow and the disperse phase was silt (silica sand) with a 2.5 wt % concentration, and a silt grain size of 70 µm was used for performing the tests. The experimental analysis showed that silt impact increases material disintegration up to 1.8 times with a change in the elbow configuration from 60° to 90° in plug flow conditions. The primary erosive wear mechanisms of the internal elbow surface were sliding, cutting, and pit propagation. The maximum silt particle impaction was located at the outer curvature in the 50° position in 60° elbows and the 80° position in 90° elbows in plug flow. The erosion rate decreased from 10.23 to 5.67 mm/year with a change in the elbow angle from 90° to 60°. Moreover, the microhardness on the Vickers scale increased from 168 to 199 in the 90° elbow and from 168 to 184 in the 60° elbow.

Media selection for anammox-based polishing filters: Balancing anammox enrichment and retention with filtration function

Retrofitting conventional denitrification filters into partial denitrification-anammox (PdNA)- or anammox (AnAOB)-based filters will reduce the needs for external carbon addition. The success of AnAOB-based filters depends on anammox growth and retention within such filters. Studies have overlooked the importance of media selection and its impact on AnAOB capacity, head loss progression dynamics, and shear conditions applied onto the AnAOB biofilm. The objective of this study was to evaluate viable media types (10 types) that can enhance AnAOB rates for efficient nitrogen removal in filters. Given the higher backwash requirement and lower AnAOB capacity of the conventionally used sand, expanded clay (3-5 mm) was recommended for AnAOB-based filters in this study. Owing to its surface characteristics, expanded clay had higher AnAOB activity (304- vs. 104-g NH₄ ⁺ -N/m² /day) and higher AnAOB retention (43% more) than sand. Increasing the iron content of expanded clay to 37% resulted in an increase in zeta potential, which led to 56% more anammox capacity compared to expanded clay with 7% iron content. This work provides insight into the importance of media types in the growth and retention of AnAOB in filters, and this knowledge could be used as basis in the development of PdNA filters. PRACTITIONER POINTS: Expanded clay showed the lowest head loss buildup and most likely will result in longer runtime for full-scale PdNA applications The highest AnAOB rates were achieved in expanded clay types and sand compared with smaller media typically used in biofiltration Expanded clay resulted in better AnAOB retention under shear, whereas sand could not withstand shear and required more frequent backwashing Expanded clay iron coating enhanced AnAOB enrichment and retention, most likely due to increased surface roughness and/or positive charge.

The Role of Seasonal Sediment Transport and Sintering in Shaping Titan's Landscapes: A Hypothesis

Titan is a sedimentary world, with lakes, rivers, canyons, fans, dissected plateaux, and sand dunes. Sediments on Saturn's moon are thought to largely consist of mechanically weak organic grains, prone to rapid abrasion into dust. Yet, Titan's equatorial dunes have likely been active for 10s-100s kyr. Sustaining Titan's dunes over geologic timescales requires a mechanism that produces sand-sized particles at equatorial latitudes. We explore the hypothesis that a combination of abrasion, when grains are transported by winds or methane rivers, and sintering, when they are at rest, could produce sand grains that maintain an equilibrium size. Our model demonstrates that seasonal sediment transport may produce sand under Titan's surface conditions and could explain the latitudinal zonation of Titan's landscapes. Our findings support the hypothesis of global, source-to-sink sedimentary pathways on Titan, driven by seasons, and mediated by episodic abrasion and sintering of organic sand by rivers and winds.

Microbial communities in sandy beaches from the three domains of life differ by microhabitat and intertidal location

The microbial communities of sandy beaches are poorly described despite the biogeochemical importance and ubiquity of these ecosystems. Using metabarcoding of the 16S and 18S rRNA genes, we investigated the diversity, microhabitats (with or between sand grains), and intertidal distributions of microorganisms (including meiofauna) from pristine sandy beaches in British Columbia, Canada, and hypothesized that abiotic variations due to microhabitat or intertidal gradients influences the distribution of microorganisms on local scales. Bacterial, archaeal, and protistan communities of the sand were clearly distinct from interstitial communities, and from planktonic communities of the overlying seawater, which correlated with differences in function and lifestyle, e.g., sulfur reduction and gliding motility. In contrast, meiofaunal communities could not be distinguished by sample type, suggesting that they are more frequently mobilized between these microhabitats. Across intertidal zones, high intertidal, mid intertidal, and low intertidal/swash communities were distinct and correlated with moisture, organic carbon and phosphate content, implying that the distribution of microorganisms is influenced by intertidal abiotic gradients. However, few taxa at the genus or species level individually contributed to this zonation pattern; rather, a unique combination of multiple microbial taxa was more likely responsible. Although significant differences in microbial community composition on sandy beaches can be attributed to microhabitat and intertidal gradients, further investigations are needed to assess community assembly processes, the consistency of these distributions, and the functions of the majority of the microorganisms observed in the sand and their effects on the biogeochemistry and ecology of sandy beaches.

Improving the Properties of Porous Geopolymers Based on TPP Ash and Slag Waste by Adjusting Their Chemical Composition

The possibility of improving the properties of porous geopolymer materials based on ash and slag waste from thermal power plants by adjusting their chemical composition is considered. An X-ray phase analysis of ash and slag wastes was carried out, the geopolymers’ precursor compositions were calculated, and additives to correct their chemical composition were selected. The samples were synthesized and their physical and mechanical properties (density, porosity, compressive strength, thermal conductivity) were analyzed. The micro- and macro-structure of the samples and the pore distribution of the obtained geopolymers were studied and pore-distribution histograms were obtained. The influence of Si:Al ratio on structural changes was described. The geopolymers’ phase composition was studied, consisting of an amorphous phase and high quartz and mullite. A conclusion about the applicability of this method for obtaining high-quality porous geopolymers was made.

Functional Links between Biomass Production and Decomposition of Vetiver (Chrysopogon zizanioides) Grass in Three Australian Soils

Plant roots are primary factors to contribute to surface and deep soil carbon sequestration (SCS). Perennial grasses like vetiver produce large and deep root system and are likely to contribute significantly to soil carbon. However, we have limited knowledge on how root and shoot decomposition differ and their contribution to SCS. This study examined biomass production and relative decomposition of vetiver which was grown under glasshouse conditions. Subsequently the biomass incubated for 206 days, and the gas analysed using ANCA-GSL. The results confirmed large shoot and root production potential of 161 and 107 Mg ha−1 (fresh) and 67.7 and 52.5 Mg ha−1 (dry) biomass, respectively with 1:1.43 (fresh) and 1:1.25 (dry) production ratio. Vetiver roots decomposed more rapidly in the clay soil (p < 0.001) compared with the shoots, which could be attributed to the lower C:N ratio of roots than the shoots. The large root biomass produced does indeed contribute more to the soil carbon accumulation and the faster root decomposition is crucial in releasing the carbon in the root exudates and would also speed up its contribution to stable SOM. Hence, planting vetiver and similar tropical perennial grasses on degraded and less fertile soils could be a good strategy to rehabilitate degraded soils and for SCS.

Climate Change Impacts on Microbiota in Beach Sand and Water: Looking Ahead

Beach sand and water have both shown relevance for human health and their microbiology have been the subjects of study for decades. Recently, the World Health Organization recommended that recreational beach sands be added to the matrices monitored for enterococci and Fungi. Global climate change is affecting beach microbial contamination, via changes to conditions like water temperature, sea level, precipitation, and waves. In addition, the world is changing, and humans travel and relocate, often carrying endemic allochthonous microbiota. Coastal areas are amongst the most frequent relocation choices, especially in regions where desertification is taking place. A warmer future will likely require looking beyond the use of traditional water quality indicators to protect human health, in order to guarantee that waterways are safe to use for bathing and recreation. Finally, since sand is a complex matrix, an alternative set of microbial standards is necessary to guarantee that the health of beach users is protected from both sand and water contaminants. We need to plan for the future safer use of beaches by adapting regulations to a climate-changing world.

Virtual Energy Management for Physical Energy Savings in a Legged Robot Hopping on Granular Media

We discuss an active damping controller to reduce the energetic cost of a single step or jump of dynamic locomotion without changing the morphology of the robot. The active damping controller adds virtual damping to a virtual leg spring created by direct-drive motors through the robot’s leg linkage. The virtual damping added is proportional to the intrusion velocity of the robot’s foot, slowing the foot’s intrusion, and thus the rate at which energy is transferred to and dissipated by the ground. In this work, we use a combination of simulations and physical experiments in a controlled granular media bed with a single-leg robot to show that the active damping controller reduces the cost of transport compared with a naive compression-extension controller under various conditions.

An assessment of three methods for extracting bacterial DNA from beach sand

AIMS

Beach water quality is regulated by faecal indicator bacteria levels, sand is not, despite known human health risk from exposure to beach sand. We compared the performance of three methods to extract bacterial DNA from beach sand as a step toward a standard method.

METHODS AND RESULTS

The analytical sensitivity of quantitative polymerase chain reaction (qPCR) for Enterococcus was compared for the slurry (suspension, agitation, membrane filtration of supernatant), versus direct extraction using PowerSoil™ or PowerMax Soil™ kits. The slurry method had the lowest limit of detection at 20-80 gene copies g^-1 , recovered significantly more DNA, and the only method that detected Enterococcus by qPCR in all samples; therefore, the only method used in subsequent experiments. The slurry method reflected the spatial variability of Enterococcus in individual transect samples. Mean recovery efficiency of the microbial source tracking marker HF183 from wastewater spiked marine and freshwater beach sand was 100.8% and 64.1%, respectively, but varied, indicating that the mixing protocol needs improvement.

CONCLUSIONS

Among the three methods, the slurry method had the best analytical sensitivity and produced extracts that were useful for culture or molecular analysis.

SIGNIFICANCE AND IMPACT OF STUDY

Standardization of methods for extraction of bacterial DNA from sand facilitates comparisons among studies, and ultimately contributes to the safety of recreational beaches.

Radioactivity, Metals Pollution and Mineralogy Assessment of a Beach Stretch from the Ionian Coast of Calabria (Southern Italy)

In the present article, a case study is reported regarding an investigation carried out in order to assess radioactivity concentration, heavy metals pollution and mineralogy of a beach stretch extending from Soverato to Squillace municipalities of the Ionian coast of Calabria, South of Italy, a popular tourist destination, especially in summer. The analysis of radionuclides contents was performed by using a High Purity Germanium (HPGe) gamma-ray detector, in order to quantify the average specific activity of ²²⁶Ra, ²³²Th and ⁴⁰K natural radionuclides and ¹³⁷Cs anthropogenic radioisotope. The absorbed dose rate and the annual effective dose equivalent radiological hazard indices were also estimated. Furthermore, X-ray Fluorescence (XRF) spectrometry measurements were carried out for the quantitative elemental analysis of the sand, in order to investigate any possible chemical pollution by heavy metals. For this aim, different indices such as Enrichment Factor (EF), Geoaccumulation Index (I_geo), Contamination Factor (CF) and Pollution Load Index (PLI) were applied to estimate the level of toxicity imposed on the ecosystem by the detected heavy metals. Finally, in order to identify the crystalline mineral components of the investigated sand samples, X-ray Diffraction (XRD) and Micro-Raman Scattering (MRS) measurements were carried out.

Soil Injection Technology Using an Expandable Polyurethane Resin: A Review

The soil injection, using an expandable polyurethane resin, holds a unique potential for settlement compensation, lifting, and strengthening the foundations of existing buildings and structures. Although various research and case studies regarding this technology have been published, these studies emphasized the technology’s effectiveness in the rapid lifting process. Nevertheless, there is no complete understanding of the technology, yet, that gathers necessary data leading to a better recognition for this technology in the theoretical understanding and the practical applications. This article aims to provide a comprehensive understanding of this technology. The injection process, the resin’s mechanism, and actual propagation in the soil’s massive, the modified physic-mechanical properties of the soil, the expansion process, the consumption of the resin, and the durability are extensively reviewed in this article. Besides that, this article aims to demonstrate the advantages and limitations of this technology in practical applications. The review also explores the existing finite element models used to calculate the strength and stiffness parameters, evaluating the bearing capacity of the composite (soil-resin) and the settlement after the injection process.

An Experimental Comparison of Simple Measurements Used for the Characterization of Sand Equestrian Surfaces

Simple Summary

Consistency of equestrian surfaces can contribute to safety and performance. An optimal surface is influenced by the design and material selection as well as maintenance and climate. To improve surfaces the quantitative testing of functional surface properties must expand beyond the current testing at the highest levels of competition. More widespread quantitative measurements would have a positive influence on animal welfare and rider safety. To expand beyond the current top levels of the sport, simple tools are required that can be shown to detect relevant changes in construction and maintenance. Our work suggests that the appropriate use of simple devices can help with both quality control of new surfaces and the monitoring of existing surfaces. Performance modifications to the layered surface design and addition of Geotextile were detected using the Going Stick and a simple impact test. These measured results are also influenced by other factors related to the surface condition such as moisture. Caution must be exercised in the interpretation of the results since these tools have not been demonstrated to correlate to either performance or safety of the surface. However, these results are encouraging and provide a justification for future development of this type of equipment.

Abstract

Quantitative measurements of performance parameters have the potential to increase consistency and enhance performance of the surfaces as well as to contribute to the safety of horses and riders. This study investigates how factors known to influence the performance of the surface, incorporation of a drainage package, control of the moisture control, and introduction of a geotextile reinforcement, affect quantitative measurements of arena materials. The measurements are made by using affordable lightweight testing tools which are readily available or easily constructed. Sixteen boxes with arena materials at a consistent depth were tested with the Going Stick (GS), both penetration resistance and shear, the impact test device (ITD), and the rotational peak shear device (RPS). Volumetric moisture content (VMC %) was also tested with time–domain reflectometry (TDR). Results obtained using GS, RPS, ITD, and TDR indicate that the presence of the drainage package, moisture content, and geotextile addition were detected. Alterations due to combinations of treatments could also be detected by GS, ITD, and TDR. While the testing showed some limitations of these devices, the potential exists to utilize them for quality control of new installations as well as for the monitoring of maintenance of the surfaces.

Application of an Acrylic Polymer and Epoxy Emulsion to Red Clay and Sand

The use of nontraditional soil stabilizers increases. Various new soil binding agents are under study to augment renewability and sustainability of an earth structure. However, despite increasing interest involved in red clay, there is minimal research investigating the stabilizing red clay with polymer. This paper presents the findings obtained by applying the acrylic polymer and epoxy emulsion as binding agent for red clay and that for sand. The epoxy–hardener ratio, amount of epoxy emulsion, and amount of polymer aqueous solution were manipulated to quantify their effects on red clay and sand, respectively. After compacting a pair of cylindrical samples of which diameter and height are 5 cm and 10 cm, respectively, it is cured for 3 and 7 days in a controlled condition. Each pair is produced to represent the engineering performance at each data point in the solution space. An optimal composition of the binding agents for red clay and that for sand mixture are identified by experimenting every data point. In addition, given lime into each sample, the maximum unconfined compressive strength (UCS) endured by red clay sample and that by sand sample are 2243 and 1493 kPa, respectively. The UCS obtained by the sample mixed with clay and sand reaches 2671 kPa after seven days of curing. It confirms that the addition of lime remarkably improves the UCS. When the clay–sand mixture, of which the ratio is 70:30, includes 5% lime, the UCS of the mixture outperforms. Indeed, these findings, i.e., the optimal proportion of components, may contribute to the increase of initial and long-term strength of an earth structure, hence improving the renewability and sustainability of the earth construction method.

Monitoring Urban Beach Quality on a Summer Day: Determination of the Origin of Fecal Indicator Bacteria and Antimicrobial Resistance at Prophète Beach, Marseille (France)

A highly frequented beach in Marseille, France, was monitored on an hourly basis during a summer day in July 2018, to determine possible water and sand fecal pollution, in parallel with influx of beach users from 8 a.m. to 8 p.m. Fecal indicator bacteria were enumerated, together with four host-associated fecal molecular markers selected to discriminate human, dog, horse, or gull/seagull origins of the contamination. The antimicrobial resistance of bacteria in water and sand was evaluated by quantifying (i) the class 1, 2, and 3 integron integrase genes intI, and (ii) bla_TEM, bla_CTX–M, and bla_SHV genes encoding endemic beta-lactamase enzymes. The number of beach users entering and leaving per hour during the observation period was manually counted. Photographs of the beach and the bathing area were taken every hour and used to count the number of persons in the water and on the sand, using a photo-interpretation method. The number of beach users increased from early morning to a peak by mid-afternoon, totaling more than 1,800, a very large number of users for such a small beach (less than 1 ha). An increase in fecal contamination in the water corresponded to the increase in beach attendance and number of bathers, with maximum numbers observed in the mid-afternoon. The human-specific fecal molecular marker HF183 indicated the contamination was of human origin. In the water, the load of Intl2 and 3 genes was lower than Intl1 but these genes were detected only during peak attendance and highest fecal contamination. The dynamics of the genes encoding B-lactamases involved in B-lactams resistance notably was linked to beach attendance and human fecal contamination. Fecal indicator bacteria, integron integrase genes intI, and genes encoding B-lactamases were detected in the sand. This study shows that bathers and beach users can be significant contributors to contamination of seawater and beach sand with bacteria of fecal origin and with bacteria carrying integron-integrase genes and beta lactamase encoding genes. High influx of users to beaches is a significant factor to be considered in order to reduce contamination and manage public health risk.

The Modifications of Haemoglobin, Erythropoietin Values and Running Performance While Training at Mountain vs. Hilltop vs. Seaside

Altitude training increases haemoglobin, erythropoietin values among athletes, but may have negative physiological consequences. An alternative, although less explored, that has the potential to positively influence performance while avoiding some of the negative physiological consequences of hypoxia is sand training. Ten endurance-trained athletes (age: 20.8 ± 1.4, body mass: 57.7 ± 8.2 kg, stature: 176 ± 6 cm; 5000 m 14:55.00 ± 0:30 min) performed three 21-day training camps at different locations: at a high altitude (HIGH), at the sea-level (CTRL), at the sea-level on the sand (SAND). Differences in erythropoietin (EPO) and haemoglobin (Hb) concentration, body weight, VO_2max and maximal aerobic velocity (VMA) before and after each training cycle were compared. Data analysis has indicated that training during HIGH elicited a greater increase in VO_2max (2.4 ± 0.2%; p = 0.005 and 1.0 ± 0.2%; p < 0.001) and VMA (2.4 ± 0.2%, p < 0.001 and 1.2 ± 0.2%; p = 0.001) compared with CTRL and SAND. While increases in VO_2max and VMA following SAND were greater (1.3 ± 0.1%; p < 0.001 and 1.2 ± 0.1%; p < 0.001) than those observed after CTRL. Moreover, EPO increased to a greater extent following HIGH (25.3 ± 2.7%) compared with SAND (11.7 ± 1.6%, p = 0.008) and CTRL (0.1 ± 0.3%, p < 0.001) with a greater increase (p < 0.01) following SAND compared with CTRL. Furthermore, HIGH and SAND elicited a greater increase (4.9 ± 0.9%; p = 0.001 and 3.3 ± 1.1%; p = 0.035) in Hb compared with CTRL. There was no difference in Hb changes observed between HIGH and SAND (p = 1.0). Finally, athletes lost 2.1 ± 0.4% (p = 0.001) more weight following HIGH vs. CTRL, while there were no differences in weight changes between HIGH vs. SAND (p = 0.742) and SAND vs. CTRL (p = 0.719). High-altitude training and sea-level training on sand resulted in significant improvements in EPO, Hb, VMA, and VO_2max that exceeded changes in such parameters following traditional sea-level training. While high-altitude training elicited greater relative increases in EPO, VMA, and VO_2max, sand training resulted in comparable increases in Hb and may prevent hypoxia-induced weight loss.

Effect of Particle Morphology on Stiffness, Strength and Volumetric Behavior of Rounded and Angular Natural Sand

Stress–strain and volume change behavior for clean sands which have distinct particle shape (rounded and angular) with very similar chemical (mineralogical) composition, size, and texture in one-dimensional (1D) compression and drained triaxial compression are presented. The effect of particle morphology on the crushing behavior in one-dimensional loading is explored using laser light diffraction technique which is suitable for particle crushing because of its high resolution and small specimen volume capability. Particle size distribution in both volume/mass and number distributions are considered for improved understanding associated with the process of comminution. Number distributions present a clearer picture of particle crushing. It is argued that particle crushing in granular assemblies initiates in larger particles, rather than in smaller particle. It was found that rounded sand specimens showed greater crushing than angular sand specimens with higher uniformity coefficient. In 1D compression, loose specimens compress approximately 10% more than dense specimens irrespective of particle shape. Densification of angular sand results in improvement in stiffness (approximately 40%) and is comparable to that of loose rounded sand. In general, density has a greater influence on the behavior of granular materials than particle morphology. The effect of particle shape was found to be greater in loose specimens than in dense specimens. The effect of grain shape on critical state friction angle is also quantified.

Effect of Incorporating Polyvinyl Alcohol Fiber on the Mechanical Properties of EICP-Treated Sand

Enzyme-induced calcium carbonate precipitation (EICP) technology can improve the strength of treated soil. But it also leads to remarkable brittleness of the soil. This study used polyvinyl alcohol (PVA) fiber combined with EICP to solidify sand. Through the unconfined compressive strength (UCS) test, the effect of PVA fiber incorporation on the mechanical properties of EICP-solidified sand was investigated; the distribution of CaCO₃ in the sample and the microstructure of fiber-reinforced EICP-treated sand were explored through the calcium carbonate content (CCC) test and microscopic experiment. Compared with the sand treated by EICP, the strength and stiffness of the sand reinforced by the fiber combined with EICP were greatly improved, and the ductility was also improved to a certain extent. However, the increase of CCC was extremely weak, and the inhomogeneity of CaCO₃ distribution was enlarged; the influence of fiber length on the UCS and CCC of the treated sand was greater than that of the fiber content. The improvement of EICP-solidified sand by PVA fiber was mainly due to the formation of a "fiber-CaCO₃-sand" spatial structure system through fiber bridging, not the increase of CCC.

The Injury Mechanism of Traumatic Amputation

Traumatic amputation has been one of the most defining injuries associated with explosive devices. An understanding of the mechanism of injury is essential in order to reduce its incidence and devastating consequences to the individual and their support network. In this study, traumatic amputation is reproduced using high-velocity environmental debris in an animal cadaveric model. The study findings are combined with previous work to describe fully the mechanism of injury as follows. The shock wave impacts with the casualty, followed by energised projectiles (environmental debris or fragmentation) carried by the blast. These cause skin and soft tissue injury, followed by skeletal trauma which compounds to produce segmental and multifragmental fractures. A critical injury point is reached, whereby the underlying integrity of both skeletal and soft tissues of the limb has been compromised. The blast wind that follows these energised projectiles completes the amputation at the level of the disruption, and traumatic amputation occurs. These findings produce a shift in the understanding of traumatic amputation due to blast from a mechanism predominately thought mediated by primary and tertiary blast, to now include secondary blast mechanisms, and inform change for mitigative strategies.

Warsaw Glacial Quartz Sand with Different Grain-Size Characteristics and Its Shear Wave Velocity from Various Interpretation Methods of BET

After obtaining the value of shear wave velocity (V_S) from the bender elements test (BET), the shear modulus of soils at small strains (G_max) can be estimated. Shear wave velocity is an important parameter in the design of geo-structures subjected to static and dynamic loading. While bender elements are increasingly used in both academic and commercial laboratory test systems, there remains a lack of agreement when interpreting the shear wave travel time from these tests. Based on the test data of 12 Warsaw glacial quartz samples of sand, primarily two different approaches were examined for determining V_S. They are both related to the observation of the source and received BE signal, namely, the first time of arrival and the peak-to-peak method. These methods were performed through visual analysis of BET data by the authors, so that subjective travel time estimates were produced. Subsequently, automated analysis methods from the GDS Bender Element Analysis Tool (BEAT) were applied. Here, three techniques in the time-domain (TD) were selected, namely, the peak-to-peak, the zero-crossing, and the cross-correlation function. Additionally, a cross-power spectrum calculation of the signals was completed, viewed as a frequency-domain (FD) method. Final comparisons between subjective observational analyses and automated interpretations of BET results showed good agreement. There is compatibility especially between the two methods: the first time of arrival and the cross-correlation, which the authors considered the best interpreting techniques for their soils. Moreover, the laboratory tests were performed on compact, medium, and well-grained sand samples with different curvature coefficient and mean grain size. Investigation of the influence of the grain-size characteristics of quartz sand on shear wave velocity demonstrated that V_S is larger for higher values of the uniformity coefficient, while it is rather independent of the curvature coefficient and the mean grain size.

A Systematic Review and Meta-Analysis

The aim of this study was to analyze the influence of natural turf, artificial turf, and sand on sprint performance in different sports and to determine how the sport surface affects sprint performance. A systematic search was conducted in Pubmed, Web of Sciences, and SPORTDiscus databases. Out of 5644 studies, 11 studies were included in the meta-analysis. The studies were very heterogeneous, as they examined different structural characteristics or quality parameters. The studies on natural turf and sand showed significant improvements on sprint speed during training. On the other hand, the analysis of fatigue did not reveal significant differences in the deterioration of sprint speed on both natural and artificial turf. Significance was set at p < 0.05. In conclusion, although lower performance in sprint was reported on sand, further studies are needed to explain the differences in sprint on natural and artificial turf.

Simulation of Bullet Fragmentation and Penetration in Granular Media

The aim of this work is to simulate the fragmentation of bullets impacted through granular media, in this case, sand. In order to validate the simulation, a group of experiments were conducted with the sand contained in two different box prototypes. The walls of the first box were constructed with fiberglass and the second with plywood. The prototypes were subjected to the impact force of bullets fired 15 m away from the box. After the shots, X-ray photographs were taken to observe the penetration depth. Transient numerical analyses were conducted to simulate these physical phenomena by using the smooth particle hydrodynamics (SPH) module of ANSYS^® 2019 AUTODYN software. Advantageously, this module considers the granular media as a group of uniform particles capable of transferring kinetic energy during the elastic collision component of an impact. The experimental results demonstrated a reduction in the maximum bullet kinetic energy of 2750 J to 100 J in 0.8 ms. The numerical results compared with the X-ray photographs showed similar results demonstrating the capability of sand to dissipate kinetic energy and the fragmentation of the bullet caused at the moment of impact.

Cytological analysis of integumentary and muscular adaptations in three sand-dwelling marine teleosts, Ammodytes tobianus (Ammodytidae), Gorgasia preclara (Congridae) and Heteroconger hassi (Congridae) (Teleostei; Actinopterygii)

Sandy bottoms are a ubiquitous environment found from sea bottoms to intertidal and freshwater zones. They are inhabited by many invertebrates and vertebrates which have developed morphological and physiological adaptations to sustain life under these particular conditions. Sandy habitats exhibit three potential constraints: abrasion, hypoxia and mechanical resistance. Here, three teleost species living in sandy environments were investigated: Ammodytes tobianus (Ammodytidae), Gorgasia preclara and Heteroconger hassi (Congridae). These teleost fishes were studied for their integument and muscular systems, which are potentially subject to sand abrasion and hypoxia, respectively. Based on histochemistry and transmission electron microscopy, we found the complex mucus system of G. preclara and H. hassi consists of two types of goblet cells and one type of sacciform cell. The secretions of both species are made of complex polysaccharides. In contrast, the scaly integument of A. tobianus has only a few goblet cells and no sacciform cells. We also highlighted, by immunohistochemistry, that the epidermal cell proliferation was much higher for this latter species, potentially resulting from the high rate of sand abrasion when A. tobianus buries itself quickly in the substrate. For all species, the major muscle fibre type was revealed by histoenzymology and corresponds to fast glycolytic fibres followed by intermediate fibres with slow fibres in the lowest proportion. Ammodytes tobianus possesses the highest fast fibre proportion (about 87% for A. tobianus and 75-78% for both garden eels). Our results provide new insights into the previously poorly studied teleost species, such as G. preclara, and allow us to highlight the complex skin histology of both garden eel species. Furthermore, the previously unknown muscle typing of these three species was determined.

A New Understanding of the Mechanism of Injury to the Pelvis and Lower Limbs in Blast

Dismounted complex blast injury (DCBI) has been one of the most severe forms of trauma sustained in recent conflicts. This injury has been partially attributed to limb flail; however, the full causative mechanism has not yet been fully determined. Soil ejecta has been hypothesized as a significant contributor to the injury but remains untested. In this study, a small-animal model of gas-gun mediated high velocity sand blast was used to investigate this mechanism. The results demonstrated a correlation between increasing sand blast velocity and injury patterns of worsening severity across the trauma range. This study is the first to replicate high velocity sand blast and the first model to reproduce the pattern of injury seen in DCBI. These findings are consistent with clinical and battlefield data. They represent a significant change in the understanding of blast injury, producing a new mechanistic theory of traumatic amputation. This mechanism of traumatic amputation is shown to be high velocity sand blast causing the initial tissue disruption, with the following blast wind and resultant limb flail completing the amputation. These findings implicate high velocity sand blast, in addition to limb flail, as a critical mechanism of injury in the dismounted blast casualty.

Behavior of the Reststrahlen Band in the 17-25 m Spectral Region in the Diffuse Reflection Spectra of Sand and Silt Mixtures

Studies on the reflectance spectra of different mixtures of sand and silt were performed in the infrared spectral region of 7-25 µm to explore the behavior of a second reststrahlen band occurring between 17 and 25 µm with respect to different mixtures of sand and silt. The reflectance spectrum of all samples exhibited reststrahlen bands within both the long wavelength infrared (LWIR) and the very long wavelength infrared (VLWIR) regions of the reflectance spectrum. Results demonstrate that both LWIR and VLWIR reststrahlen bands increase in area as the fraction of sand increases to 80%. More importantly, the data demonstrate that the VLWIR reststrahlen band, like that in LWIR, exhibits a significant and reproducible decrease in reflectivity for mixed soil versus weathered soil.

Recycled Glass as a Substitute for Quartz Sand in Silicate Products

In 2016, an average of 5.0 tons of waste per household was generated in the European Union (including waste glass). In the same year, 45.7% of the waste glass in the EU was recycled. The incorporation of recycled waste glass in building materials, i.e., concrete, cements, or ceramics, is very popular around the world because of the environmental problems and costs connected with their disposal and recycling. A less known solution, however, is using the waste glass in composite products, including sand-lime. The aim of this work was to assess the role of recycled container waste glass in a sand-lime mix. The waste was used as a substitute for the quartz sand. To verify the suitability of recycled glass for the production of sand-lime products, the physical and mechanical properties of sand-lime specimens were examined. Four series of specimens were made: 0%, 33%, 66%, and 100% of recycled waste glass (RG) as a sand (FA) replacement. The binder mass did not change (8%). The research results showed that ternary mixtures of lime, sand, and recycled waste glass had a higher compressive strength and lower density compared to the reference specimen. The sand-lime specimen containing 100% (RG) increased the compressive strength by 287% compared to that of the control specimen. The increase in the parameters was proportional to the amount of the replacement in the mixtures.