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Abstract This study introduces microbiologically induced calcium phosphate precipitation (MICPP) as a novel and environmentally sustainable method of soil stabilization. Using Limosilactobacillus sp., especially NBRC 14511 and fish bone solution (FBS) extracted from Tuna fish bones, the study was aimed at testing the feasibility of calcium phosphate compounds (CPCs) deposition and sand stabilization. Dynamic changes in pH and calcium ion (Ca2+) concentration during the precipitation experiments affected the precipitation and sequential conversion of dicalcium phosphate dihydrate (DCPD) to hydroxyapatite (HAp), which was confirmed by XRD and SEM analysis. Sand solidification experiments demonstrated improvements in unconfined compressive strength (UCS), especially at higher Urea/Ca2+ ratios. The UCS values obtained were 10.35 MPa at a ratio of 2.0, 3.34 MPa at a ratio of 1.0, and 0.43 MPa at a ratio of 0.5, highlighting the advantages of MICPP over traditional methods. Microstructural analysis further clarified the mineral composition, demonstrating the potential of MICPP in environmentally friendly soil engineering. The study highlights the promise of MICPP for sustainable soil stabilization, offering improved mechanical properties and reducing environmental impact, paving the way for novel geotechnical practices.

Highly plastic clays pose significant challenges in engineering projects. Various techniques have been employed to enhance their properties, though many face difficulties related to implementation and environmental impact. This study examines the effect of CO2-induced magnesium carbonate on improving the geotechnical behavior of plastic clay. CO2-induced magnesium carbonate was produced via mineral carbonation and used to improve the behavior of highly plastic natural clay. CO2 gas was injected into a sodium hydroxide solution to produce carbonate ions (CO32−). Magnesium carbonate was precipitated on a laboratory scale by adding magnesium sulfate solution to the carbonate ion solution. Clayey soil samples were obtained from test pits in the Meyghan Plain near Arak, Iran. The clay samples were treated with different percentages of the produced magnesium carbonate. Various parameters of the treated and untreated samples, including index properties, unconfined compressive strength, consolidation behavior, and swelling potential, were studied. It was found that the liquid limit and plasticity index of the treated clay decreased as the magnesium carbonate content increased. The soil classification changed from high plastic clay (CH) to low plastic silt (ML) with the addition of 15% magnesium carbonate to the highly plastic clay. The unconfined compressive strength of the treated clay increased. Additionally, the consolidation behavior and swelling index of the treated clay improved as the magnesium carbonate content increased. This study confirms that CO2-induced magnesium carbonate is a promising material for improving the behavior of highly plastic clays, offering a sustainable approach to environmental management.

Biomineralization occurring in living organisms is mostly controlled by organic macromolecules such as polysaccharides and proteins. Recently, biomineralization has been attracting much attention as a green and sustainable cementation technique including enzyme-induced carbonate precipitation (EICP), where CaCO3 is formed by hydrolysis of urea by urease in the presence of calcium ions. In this study, we have developed a novel hybrid biocementation method combining CaCO3 and cellulose nanofiber (CNF). In nature, matrix proteins work as a binder at the interface of organic and inorganic materials to form hybrid biomaterials. By mimicking the natural system, we designed an artificial fusion protein to facilitate the deposition of CaCO3 on CNF. Calcite-binding peptide (CaBP) and carbohydrate-binding module (CBM) were introduced in the artificial fusion protein CaBP-CBM to connect CaCO3 and cellulose. The addition of CNF in the EICP system resulted in the formation of a number of small particles of CaCO3 compared to a non-additive system. The addition of the fusion protein CaBP-CBM to CNF led to an increase in the size of CaCO3 particles. Furthermore, the combination of CaBP-CBM and CNF provides higher strength of samples in sand solidification. Therefore, introduction of CNF and the fusion protein would be promising for novel biocementation techniques.

Enzyme induced carbonate precipitation (EICP) which applied to improve the quality of recycled aggregates (RA) is a novel technology in the field of civil engineering. The urease was extracted from soybean, and the factors including soybean powder concentration, temperature and pH value on urease activity were investigated. Then the EICP reaction kinetics was carried out to obtain the most suitable reaction environment. A spraying method instead of soaking method for modifying RA was proposed, and the physical and mechanical properties of RA were evaluated by water absorption, hardness, apparent density and crushing index. The results show that the optimum pH value of soybean urease is 8.0, the concentration of soybean power is 40 g/L, and the urease activity increases with temperature in the range of 10–50 °C. Spraying method was better than soaking method in water absorption reduction rate of RA with different particle sizes. When the concentration of the chemical solution is 0.5 mol/L, the improvement in the water absorption characteristics of the RA is most significant. And the modified RA have also undergone substantial improvements in terms of hardness and apparent density. On the 7-day of modification, the crushing index of the RA reaches the peak. Through microscopic observation, the pore volume of the modified RA is significantly reduced, and the content of CaCO3 is significantly increased, and the main crystalline form of CaCO3 are calcite and vaterite.

Introduction: Bio-cementation processes [namely, microbial induced carbonate precipitation (MICP) and enzyme induced carbonate precipitation (EICP)] have recently become promising techniques for solidifying loose sands. However, these methods release gaseous ammonia to the atmosphere, which is not desirable for real-scale applications. This study aims to propose an enzyme induced calcium phosphate precipitation (EICPP) method as a sustainable direction for the solidification of sand.Methods: Precipitation of calcium phosphate compound (CPC) was driven through pH-dependent mechanism regulated by enzymatic hydrolysis of urea. The baseline study was designed to consist of a series of precipitation tests and sand column tests, evaluating the influence of various recipes of cementation media (CM) on treatment efficiency. The evaluation program consisted of Unconfined compression tests, precipitation content measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction.Results: The observations showed that the content of urea had an important role in proposed EICPP treatment, which determined the extent of the pH increase. This increase had a great influence on 1) utilization of soluble calcium, 2) precipitation content of calcium phosphate, and 3) the morphology of the precipitates. Results of sand column test suggested that injecting CM that consisted of acid-dissolved bone meal, urea and urease enzyme could result in the deposition of insoluble CPC that enabled the solidification of sand particles.Discussion: The precipitation quantity was found to increase with the increase in urea content; however, the treatment media with high urea content resulted amorphous-like crystals. The plate-like crystals were evidenced in CM with [Ca]/[urea] molar ratio between 1.5–2.0. X-ray Diffraction (XRD) analysis revealed that irrespective of the urea contents, the formed crystals were identified as brushite. Since the final pH of proposed EICPP method could be controllable within acidic-neutral conditions, the emission of ammonia gas would be eliminated.

Microbial-induced carbonate precipitation (MICP) is an environmentally friendly approach that relies on the production of calcium carbonate by microorganisms to construct or reinforce coastal structures. In order to address the disadvantages of current coastal countermeasures techniques, MICP is a cost-effective solution that can be used to repair and restore coastal habitats damaged by human activities. The resulting structures formed through MICP are strong and durable, providing long-term protection against erosion and flooding caused by storms or rising sea levels. Biominerals, including calcium carbonate or calcium phosphate, are used to create complex composites with organic molecules by combining the strength of inorganic materials with the versatility and biocompatibility of organic macromolecules. It is of the utmost importance to investigate the functionality of MICP and scale up its deployment in various fields in order to thoroughly assess the instrument’s application. Coastal erosion has been a severe concern in archipelagic countries. Therefore, this study explored the Miyazaki coast in Japan and the Yogyakarta coastline in Indonesia to minimize coastal erosion using MICP. The bacteria found in Miyazaki (Sporosarcina species) and the Yogyakarta coast (Pseudoalteromonas tetradonis) were used in the experiment. As a result, the sample treated with a gradual injection of the cementation solution achieved about 6 MPa UCS after 21 days of treatment. The objective were investigated the potential biotreatment with original sand materials and to evaluate the long-term durability under saturated conditions. For these purposes, the MICP-treated sand columns were subjected to series of compression tests and wet-drying (WD) durability analysis.

ABSTRACT USA300, a major Panton–Valentine leukocidin (PVL)-producing methicillin-resistant Staphylococcus aureus (MRSA) clone associated with skin and soft tissue infections (SSTIs), carries a type IV staphylococcal cassette chromosome mec (SCCmec) element. Recently, a USA300 variant, ΨUSA300, with a 12-bp deletion of ccrB2 in the SCCmec element, was identified in Japan by Takadama et al. (15). To understand the current status of PVL-positive MRSA in the community, a nationwide surveillance of MRSA isolated from outpatients at dermatology departments was conducted. This study included 1,619 outpatients who visited dermatology departments at 22 healthcare facilities in 11 prefectures in Japan between 2018 and 2021; S. aureus were isolated from these outpatients. Molecular epidemiological analysis was performed using PCR, SCCmec and spa typing, pulsed-field gel electrophoresis, multilocus sequence typing, and antimicrobial susceptibility testing. A total of 980 S. aureus were isolated, 293 of which were identified as MRSA. Among MRSA isolates, PVL genes were detected in 18 of 63 (28.6%) in 2018, 34 of 85 (40.0%) in 2019, 29 of 65 (44.6%) in 2020, and 40 in 80 (50.0%) in 2021. Among the PVL-positive MRSA, 16 of 121 (13.2%) and 94 of 121 (77.7%) isolates were identified as USA300 and ΨUSA300, respectively. ΨUSA300 strains were collected from six prefectures in Japan: Kagawa, Osaka, Tokyo, Kanagawa, Fukushima, and Saitama. ΨUSA300 was isolated more frequently than USA300 from patients with deep-seated SSTIs (P < 0.05). Our findings showed that PVL-positive MRSA isolates were significantly increased in the Japanese community. Furthermore, the USA300 variant ΨUSA300 has emerged as the predominant PVL-positive MRSA clone across the Kanto, Kinki, and Shikoku regions of Japan, and this variant may possess a greater propensity to cause deep-seated SSTIs than in USA300. IMPORTANCE USA300 is an MRSA clone producing PVL, a toxin associated with SSTIs. ΨUSA300 is a USA300 variant recently identified in Japan by Takadama et al. (15). Here, we found that the prevalence rate of PVL-positive MRSA in S. aureus was elevated in the Japanese community, and ΨUSA300 accounted for most of them. ΨUSA300 strains have been isolated from several areas in Japan and were associated with deep-seated SSTIs. This study highlighted the emerging threat posed by ΨUSA300 in Japan.

Microbial induced carbonate precipitation (MICP) is a promising bio-cementation method that involves ureolytic bacteria to improve the geotechnical properties of soil. The laboratory-scale studies carried out in the recent past showed that the MICP can be a potential alternative for slope surface preservation. However, the use of analytical-grade chemicals makes this method too expensive, limiting the applicability of the method especially when implicated at field-scale. The purpose of this research work was to assess the effectiveness of using inexpensive low-grade chemicals for the in-situ stabilization of slope surface. Two test plots were established at the project site (Hokkaido expressway slope, Japan) and subjected to MICP treatment via surficial spraying. One was treated using the cementation media formulated by low-grade chemicals (inclusive of fertilizer urea, snow-melting agent and beer-yeast), while the typical analytical-grade media was used to treat the other plot. After 20 days of treatment, the treated slope surfaces were evaluated by surface strength, CaCO3 content, scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The outcomes indicated that the surface was significantly improved by low-grade chemicals; a stiff surface layer was desirably formed to the depth of 5 – 10 cm with the surface strength and CaCO3 content in the ranges of 0.14 – 1.02 MPa and 0.56 – 3.7%, respectively. The results are compared and discussed, and the challenges in the use of low-grade chemicals are pointed out for the way forward. Cost analysis disclosed that the material cost of the cementation media was reduced by around thirty-seven-fold (by 97%) compared to the analytical-grade media. While demonstrating the potential use of low-grade chemicals, the field-scale experiment could contribute to narrow down the gap between the present-state and real-scale deployment of MICP technology.

Microbial induced carbonate precipitation (MICP) through the ureolysis metabolic pathway is one of the most studied topics in biocementation due to its high efficiency. Although excellent outcomes have proved the potential of this technique, microorganisms face some obstacles when considering complicated situations in the real field, such as bacterial adaptability and survivability issues. This study made the first attempt to seek solutions to this issue from the air, exploring ureolytic airborne bacteria with resilient features to find a solution to survivability issues. Samples were collected using an air sampler in Sapporo, Hokkaido, a cold region where sampling sites were mostly covered with dense vegetation. After two rounds of screening, 12 out of 57 urease-positive isolates were identified through 16S rRNA gene analysis. Four potentially selected strains were then evaluated in terms of growth pattern and activity changes within a range of temperatures (15°C–35°C). The results from sand solidification tests using two Lederbergia strains with the best performance among the isolates showed an improvement in unconfined compressive strength up to 4–8 MPa after treatment, indicating a high MICP efficiency. Overall, this baseline study demonstrated that the air could be an ideal isolation source for ureolytic bacteria and laid a new pathway for MICP applications. More investigations on the performance of airborne bacteria under changeable environments may be required to further examine their survivability and adaptability.

Abstract Biocementation using enzyme induced carbonate precipitation (EICP) process has become an innovative method for soil improvement. One of the major limitations in scaling-up of biocement treatment is the emission of gaseous ammonia during the urea hydrolysis, which is environmentally hazardous. In order to eliminate this shortcoming, this paper presents a series of experiments performed to evaluate a novel approach for preventing the ammonia byproducts in the EICP process via the use of polyacrylic acid (PAA). Through the adjustment of the pH to acidic, PAA not only promotes the enzyme activity, but also averts the conversion of ammonium to gaseous ammonia and its release, thus preventing any harm to the environment. The sand samples were treated with cementation solution and assessed for improvement in strength. Calcium carbonate content measurements and X-ray powder diffraction analysis identified the calcite crystals precipitated in the soil pores. Scanning electron microscopy analysis clearly showed that calcium carbonate was precipitated connecting soil particles, thus providing a uniaxial compressive strength (UCS) of up to 1.65 MPa. Overall, the inhibition in the speciation of gaseous ammonia shows the great potential of PAA for large-scale promotion of biocement.

Microbial Induced Carbonate Precipitation (MICP) has recently become a new technology for stabilizing the slope surface. The applicability of MICP, however, is limited in fine-grained soils due to the restrictions regarding the transportation of bacteria cells. The purpose of this study was to assess the feasibility of an alternative called Bacterial-Enzyme Induced Carbonate Precipitation (B-EICP) for stabilizing the fine-grained slope soils. Unlike the MICP strategy (involving whole-cells of bacteria), the proposed B-EICP utilizes bacterial urease to induce the bio-cement formation within soil. The whole-cell culture of Lysinibacillus xylanilyticus was subjected to cyclic sonication to extract the free urease suspension. The B-EICP treatment was performed to the columns prepared using two different soils obtained from representative expressway slopes. The cementation responses of the proposed B-EICP were compared with that of typical MICP method, especially from the following viewpoints, (i) adaptability to soil with high fine-grained content, (ii) conditions under which B-EICP can be effectively applied and (iii) cementation under low temperature. The results revealed that the extract solution had higher urease activity compared to original bacteria culture, and the activity remained more stable at low temperature conditions (15°C). The results further confirmed that B-EICP method is more suitable for stabilizing soils with large amount of fine particles. Comparing with MICP, the B-EICP resulted higher unconfined compressive strength (over 1200 kPa) and deeper cementation in the silty sand. Microscale analysis suggested that the B-EICP could induce smaller calcium carbonate crystals than that by MICP, but the number of crystals in B-EICP were significantly more, thus contributed to increased particle-particle cementation.

This study aimed to investigate the structure and shape of carbonate crystals induced through microbial activity and carbon dioxide reactions in the sand. The strength of sandy soil treated with carbonate minerals was subsequently determined using unconfined compression strength (UCS) tests. Sporoscarcina pasteurii bacteria were used to produce an aqueous solution of free carbonate ions (CO32−) under laboratory circumstances called microbial-induced carbonate precipitation (MICP). In CO2-induced carbonate precipitation (CICP), carbon dioxide was added to a sodium hydroxide solution to form free carbonate ions (CO32−). Different carbonate mineral compositions were then provided by adding Fe2+, Mg2+, and Ca2+ ions to carbonate ions (CO32−). In the MICP and CICP procedures, the results of scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) revealed a distinct morphology of any type of carbonate minerals. Vaterite (CaCO3), siderite (FeCO3), nesquehonite (MgCO3(H2O)3), and dolomite (CaMg(CO3)2 were produced in MICP. Calcite (CaCO3), siderite (FeCO3), nesquehonite (MgCO3(H2O)3), and high-Mg calcite (Ca-Mg(CO3)) were produced in CICP. According to UCS data, siderite and high-Mg calcite/dolomite had more effectiveness in increasing soil strength (63–72 kPa). The soils treated with nesquehonite had the lowest strength value (25–29 kPa). Mineral-treated soils in CICP showed a slightly higher UCS strength than MICP, which could be attributable to greater particle size and interlocking. This research focused on studying the mineralogical properties of precipitated carbonate minerals by CICP and MICP methods to suggest a promising environmental method for soil reinforcement.

For over a thousand years, many ancient cements have remained durable despite long-term exposure to atmospheric or humid agents. This review paper summarizes technologies of worldwide ancient architectures which have shown remarkable durability that has preserved them over thousands of years of constant erosion. We aim to identify the influence of organic and inorganic additions in altering cement properties and take these lost and forgotten technologies to the production frontline. The types of additions were usually decided based on the local environment and purpose of the structure. The ancient Romans built magnificent structures by making hydraulic cement using volcanic ash. The ancient Chinese introduced sticky rice and other local materials to improve the properties of pure lime cement. A variety of organic and inorganic additions used in traditional lime cement not only changes its properties but also improves its durability for centuries. The benefits they bring to cement may also be useful in enzyme-induced carbonate precipitation (EICP) and microbially induced carbonate precipitation (MICP) fields. For instance, sticky rice has been confirmed to play a crucial role in regulating calcite crystal growth and providing interior hydrophobic conditions, which contribute to improving the strength and durability of EICP- and MICP-treated samples in a sustainable way.

Greenhouse gas emissions are a critical problem nowadays. The cement manufacturing sector alone accounts for 8% of all human-generated emissions, and as the world’s population grows and globalization intensifies, this sector will require significantly more resources. In order to fulfill the need of geomaterials for construction and to reduce carbon dioxide emissions into the atmosphere, conventional approaches to soil reinforcement need to be reconsidered. Calcium phosphate compounds (CPCs) are new materials that have only recently found their place in the soil reinforcement field. Its eco-friendly, non-toxic, reaction pathway is highly dependent on the pH of the medium and the concentration of components inside the solution. CPCs has advantages over the two most common environmental methods of soil reinforcement, microbial-induced carbonate precipitation (MICP) and enzyme induced carbonate precipitation (EICP); with CPCs, the ammonium problem can be neutralized and thus allowed to be applied in the field. In this review paper, the advantages and disadvantages of the engineering uses of CPCs for soil improvement have been discussed. Additionally, the process of how CPCs perform has been studied and an analysis of existing studies related to soil reinforcement by CPC implementation was conducted.

Peat is one of the most challenging and problematic soils in the fields of geotechnical and environmental engineering. The most critical problems related to peat soils are extremely low strength and high compressibility, resulting in poor inhabitancy and infrastructural developments in their vicinity. Thus far, peat soils were stabilized using Portland cement; however, the production of Portland cement causes significant emission of greenhouse gases, which is not environmentally desirable. Microbial-induced carbonate precipitation (MICP) is an innovative technique for improving the mechanical properties of soil through potentially environmentally friendly processes. This article presents a laboratory study carried out with the aim of investigating the viability and effect of scallop shell powder (SSP) on enhancing the mechanical properties of the MICP-treated amorphous peat. The hypothesis was that the distribution of SSP (as-derived calcite particles) would (i) provide more nucleation sites to precipitates and (ii) increase the connectivity of MICP bridges to facilitate mineral skeleton to amorphous peat, accompanied by an increase in its compressive strength. Specimens were treated at varying combinations of SSP and MICP reagents, and the improvement was comprehensively assessed through a series of unconfined compression tests and supported by microscale and chemical analyses such as scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction analysis. The outcomes showed that incorporating SSP in MICP treatment would be a promising approach to treat amorphous peat soils. The proposed approach could improve the unconfined compressive strength by over 200% after a 7-day curing period, while the conventional MICP could not exhibit any significant improvements.

Human activity affects both natural resources and spatial land use, including its utilization as sand mining sites. Sand mines, as a pillar of building construction, have been over excavated in certain areas, which has impacted the environment. In this research, the purpose of this study was to determine a spatial allocation of the mining designation area that will not damage the groundwater flow. Therefore, it is imperative for understanding the depth of groundwater at the study site, understanding the direction of groundwater flow, and the impact of mining activities on groundwater based on the combination of geophysical and geological approaches to improve the current government policy. A geological-geophysics approach, vertical electrical sounding (VES), was followed at 12 different locations surrounding the Kertek District, which has a general geological formation of igneous volcanic rock sediment. The result of the geophysical measurements (possibilities) indicates the presence of shallow, medium, and deep groundwater aquifers, which tended to follow the slope direction to the south. This may be due to the unsaturated soil conditions as the geoelectrical measurements were taken at the beginning of the rainy season. Finally, the goals of this research were to integrate resources with spatial characteristics to allow proper resources management.

Coronavirus disease 2019 (COVID-19) is an acute respiratory syndrome caused by SARS-CoV-2 and is known to cause respiratory and systemic symptoms. A SARS-CoV-2 infection is involved in aneurysm formation, enlargement, and rupture in medium-sized vessels, such as the cerebral and coronary arteries and the aorta. In contrast, its involvement in forming aneurysms in medium-sized vessels other than the cerebral and coronary arteries has not been reported. An 84-year-old Japanese man with COVID-19 was admitted to our hospital. The treatment course was favorable, and the COVID-19 treatment was completed by the 10th day. On day 14, pancreatic enzymes increased mildly. An abdominal computed tomography revealed a ruptured left gastric aneurysm after spontaneous hemostasis. Arterial embolization was performed. In this patient, a new left gastric aneurysm was suspected of having formed and ruptured during the course of the COVID-19 treatment. To the best of our knowledge, this is the first report of abdominal visceral aneurysm formation caused by COVID-19 in a medium-sized vessel, and it is necessary to remember that aneurysms can be formed at any site when treating this syndrome.

Soil improvement via MICP (microbially induced carbonate precipitation) technologies has recently received widespread attention in the geoenvironmental and geotechnical fields. The durability of MICP-treated samples remains a critical concern in this novel method. In this work, fiber (jute)-reinforced MICP-treated samples were investigated to evaluate their durability under exposure to distilled water (DW) and artificial seawater (ASW), so as to advance the understanding of long-term performance mimicking real field conditions, along with improvement of the MICP-treated samples for use in coastal erosion protection. Primarily, the results showed that the addition of fiber (jute) improved the durability of the MICP-treated samples by more than 50%. Results also showed that the wet–dry (WD) cyclic process resulted in adverse effects on the mechanical and physical characteristics of fiber-reinforced MICP-treated samples in both DW and ASW. The breakdown of calcium carbonates and bonding effects in between the sand particles was discovered to be involved in the deterioration of MICP samples caused by WD cycles, and this occurs in two stages. The findings of this study would be extremely beneficial to extend the insight and understanding of improvement and durability responses for significant and effective MICP treatments and/or re-treatments.

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from two different geological and geographical localities: Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. In addition, in order to investigate a potential soft engineering method to protect coasts from erosion, artificial beachrock samples were created in vitro using sand samples and ureolytic bacteria from both areas under accelerating conditions. For Okinawa artificial beachrock experiments, the bacteria Pararhodobacter sp. was used, and for Diolkos, it was the bacteria Micrococcus yunnainensis sp. For the natural beachrocks, a multi-analytical approach was accomplished with the use of microscopic investigation, a scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray fluorescence. Correlations were made between natural and artificial beachrocks. Results have shown that Diolkos beachrock was formed in the upper part of the intertidal zone, consisting of detrital material originating from the local bedrock, while Sumuide beachrock formed in the low intertidal–upper subtidal zone, consisting of coral sand and foraminifera fragments. For the artificial beachrocks, three samples were created using the microbial-induced carbonate precipitation (MICP) method, one from Diolkos (Corinth, Greece) and two from Sumuide (Okinawa, Japan). Diolkos artificial beachrock was better consolidated in comparison to Sumuide. Our investigation has shown that bacterial density was the key factor for the creation of the artificial beachrocks, while the samples’ granulometry played a secondary role in the process. The laboratory artificial beachrocks show encouraging results for a new soft engineering method to encounter beach erosion while keeping an ecofriendly character by saving energy, material resources and gas emissions. Artificial beachrocks can share the same properties of a natural beachrock and can contribute positively to marine biodiversity as a natural rocky habitat.

The groundwater quality in Wates coastal area is generally a good category but there are high salinity values at some locations. The chemical quality of groundwater from place to place is different. The difference of water quality is a major problem in the study area. A total of 27 groundwater samples were collected in August, 2017. Geochemical signatures of groundwater were used to analyze the major ionic concentrations in the groundwater, to identify the dominant hydrogeochemical processes, and to determine the relationship between groundwater flow and spatial distribution of water types. Hierarchical Cluster analysis and Schoeller diagram, Gibbs plots, Scatter diagrams, and Piper Trilinear diagram were employed to evaluate the hydrogeochemical evolution of groundwater. In Schoeller diagrams, the relative tendency of ions in meq/L shows Na+ > Mg2+> Ca2+> K+ and HCO3- >Cl- > SO42-trends, typically in saline water. Gibbs diagram reveals that the groundwater chemistry is mainly controlled by rock weathering with secondary contribution from evaporation source. Based on the results of Hierarchical Cluster analysis and Piper diagram, dominant hydrogeochemical facies in the study area are Ca-HCO3, Na-Cl, and Ca-Na-HCO3 types. Ca-HCO3 facies are almost throughout the study area and the evolution of groundwater was mainly controlled by the silicate weathering process. Na-Cl water types are grouping in the study area influenced by cation exchange and evaporation processes, while Ca-Na-HCO3 types are locally grouping with silicate weathering and cation exchange processes. The geology implies that common silicate minerals are found everywhere in the study area. In fact, the distributions of groundwater facies are related to the local geology, which may result in different hydrochemical processes. In addition, lithology is very influential on the existence of groundwater in the study area

Abstract Background Viral myocarditis presents with various symptoms, including fatal arrhythmia and cardiogenic shock, and may develop into chronic myocarditis and dilated cardiomyopathy in some patients. We report a case of viral myocarditis and hepatitis caused by herpes simplex virus. Case presentation A 20-year-old woman was admitted to our hospital with fever, fatigue, and anorexia. The initial investigation showed elevated liver enzyme levels and elevated creatine phosphokinase, and computed tomography showed diffuse swelling and internal heterogeneous image in the liver. These findings were consistent with acute hepatitis; therefore, we performed a liver biopsy, which showed parenchymal necrosis and lymphocytic infiltration. The night that the liver biopsy was performed, blood pressure gradually decreased and revealed cardiogenic shock. Electrocardiography showed diffuse ST-segment elevation, and echocardiography showed a dilated, spherical ventricle with reduced systolic function and pericardial effusion. An endomyocardial biopsy revealed lymphocyte infiltration of the myocardium, confirming acute myocarditis. After a few days, tests for immunoglobin M and immunoglobin G antibodies against herpes simplex virus were positive. Conclusions We presented a rare case of myocarditis combined with hepatitis that was caused by herpes simplex virus. Acute myocarditis can occur concurrently with hepatitis, pancreatitis, nephritis, and encephalitis; thus, determining the presence of other infectious lesions is necessary to provide appropriate treatment for the patient.

Recently, green materials and technologies have received considerable attention in geotechnical engineering. One of such techniques is microbially-induced carbonate precipitation (MICP). In the MICP process, CaCO3 is achieved bio-chemically within the soil, thus enhancing the strength and stiffness. The purpose of this study is to introduce the wastepaper fiber (WPF) onto the MICP (i) to study the mechanical properties of MICP-treated sand with varying WPF content (0–8%) and (ii) to assess the freeze–thaw (FT) durability of the treated samples. Findings revealed that the ductility of the treated samples increases with the increase in WPF addition, while the highest UCS is found with a small fiber addition. The results of CaCO3 content suggest that the WPF addition enhances the immobilization of the bacteria cells, thus yielding the precipitation content. However, shear wave velocity analysis indicates that a higher addition of WPF results in rapid deterioration of the samples when subjected to freeze–thaw cycles. Microscale analysis illuminates that fiber clusters replace the solid bonding at particle contacts, leading to reduced resistance to freeze–thaw damage. Overall, the study demonstrates that as a waste material, WPF could be sustainably reused in the bio-cementation.

Recently, soil improvement using EICP (Enzyme-Induced Carbonate Precipitation) methods in the geotechnical and geo-environmental field has become a prominent interest worldwide. The objective of this study was to develop an improved extraction technique of crude urease from watermelon seeds in both dry and germinated conditions. Subsequently, this study also analyzed the improvement methodology of crystal polymorphs and soil bonding incorporation of various Mg2+/Ca2+ ratios. The optimization of enzyme-mediated carbonate precipitation was also investigated by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. Results confirmed that the precipitated crystals are mainly calcite, vaterite and aragonite primarily (depending on the Mg2+/Ca2+ ratios). Therefore, to improve the bonding capacity in between the sand particles a novel improvement methodology was investigated by adding various Mg2+/Ca2+ ratios. The mechanical properties of the treated soil (Mikawa Sand, D50 = 0.870 mm) specimens were tested by unconfined compressive strength (UCS) and this confirmed the effectiveness of adding various Mg2+/Ca2+ ratios. The results of the UCS tests showed that, the lower molar ratios of Mg2+/Ca2+ can significantly improve the UCS of the specimen (up to 50%) which could be considered a significant outcome for different bio-geotechnical applications.

The microbial-induced carbonate precipitation (MICP) method has gained intense attention in recent years as a safe and sustainable alternative for soil improvement and for use in construction materials. In this study, the effects of the addition of plant-based natural jute fibers to MICP-treated sand and the corresponding microstructures were measured to investigate their subsequent impacts on the MICP-treated biocemented sand. The fibers used were at 0%, 0.5%, 1.5%, 3%, 5%, 10%, and 20% by weight of the sand, while the fiber lengths were 5, 15, and 25 mm. The microbial interactions with the fibers, the CaCO3 precipitation trend, and the biocemented specimen (microstructure) were also evaluated based on the unconfined compressive strength (UCS) values, scanning electron microscopy (SEM), and fluorescence microscopy. The results of this study showed that the added jute fibers improved the engineering properties (ductility, toughness, and brittleness behavior) of the biocemented sand using MICP method. Furthermore, the fiber content more significantly affected the engineering properties of the MICP-treated sand than the fiber length. In this study, the optimal fiber content was 3%, whereas the optimal fiber length was s 15 mm. The SEM results indicated that the fiber facilitated the MICP process by bridging the pores in the calcareous sand, reduced the brittleness of the treated samples, and increased the mechanical properties of the biocemented sand. The results of this study could significantly contribute to further improvement of fiber-reinforced biocemented sand in geotechnical engineering field applications.

Typically, the mitigation of coastal erosion is achieved by amending surface conditions using materials, such as concrete. The objective of this study is to evaluate the feasibility of constructing artificial beachrocks using natural materials (e.g., microbes, sand, shell, pieces of coral, and seaweed, etc.) within a short time, and to propose the method as a novel strategy for coastal protection. Initially, a survey on resistivity and a multichannel analysis of seismic waves (MASW) were conducted along the coastal lines to characterize and elucidate the subsurface structure of existing beachrocks in the Southeast Yogyakarta coastal area, Krakal–Sadranan beach, Indonesia. The field survey on natural beachrocks suggested that both resistivity and shear wave velocity were higher in the deeper deposits compared to the underlying unconsolidated sand layer within a depth of approximately 1.5 m and covering an area of 210.496 m2 for the α-section and 76.936 m2 for the β-section of beachrock deposit. The results of the sand solidification test in the laboratory showed that treated sand achieved unconfined compressive strength of up to around 6 MPa, determined after a treatment period of 14 days under optimum conditions.

Isolation of ureolytic bacteria and geochemical analysis of beachrock from Krakal-Sadranan Beach (Yogyakarta, Indonesia) were conducted to determine natural sedimentary characteristics of the beachrock. The beachrock was also examined to determine the depositional conditions and distribution of rare earth elements. An increased concentration of total rare earth elements, both heavy rare earth elements (terbium, dysprosium, yttrium, holmium, erbium, thulium, ytterbium, and lutetium) and light rare earth elements (lanthanum, cesium, praseodymium, neodymium, samarium, europium, and gadolinium) signals that the beachrock deposition process happened under oxidative environmental conditions. This study proposes the novel use of ureolytic bacteria in a depositional environment for carbonate control of a sedimentary process for the development of artificial rock to mitigate coastal erosion. The resulting bacterial strains are highly homologous to the 16S rDNA nucleotide sequence of the species Oceanobacillus profundus, Vibrio maritimus, and Pseudoalteromonas tetradonis.

In recent years, traditional material for coastal erosion protection has become very expensive and not sustainable and eco-friendly for the long term. As an alternative countermeasure, this study focused on a sustainable biological ground improvement technique that can be utilized as an option for improving the mechanical and geotechnical engineering properties of soil by the microbially induced carbonate precipitation (MICP) technique considering native ureolytic bacteria. To protect coastal erosion, an innovative and sustainable strategy was proposed in this study by means of combing geotube and the MICP method. For a successful sand solidification, the urease activity, environmental factors, urease distribution, and calcite precipitation trend, among others, have been investigated using the isolated native strains. Our results revealed that urease activity of the identified strains denoted as G1 (Micrococcus sp.), G2 (Pseudoalteromonas sp.), and G3 (Virgibacillus sp.) relied on environment-specific parameters and, additionally, urease was not discharged in the culture solution but would discharge in and/or on the bacterial cell, and the fluid of the cells showed urease activity. Moreover, we successfully obtained solidified sand bearing UCS (Unconfined Compressive Strength) up to 1.8 MPa. We also proposed a novel sustainable approach for field implementation in a combination of geotube and MICP for coastal erosion protection that is cheaper, energy-saving, eco-friendly, and sustainable for Mediterranean countries, as well as for bio-mediated soil improvement.

Microbial Induced Carbonate Precipitation (MICP) via urea hydrolysis is an emerging sustainable technology that provides solutions for numerous environmental and engineering problems in a vast range of disciplines. Attention has now been given to the implementation of this technique to reinforce loose sand bodies in-situ in nearshore areas and improve their resistance against erosion from wave action without interfering with its hydraulics. A current study has focused on isolating a local ureolytic bacterium and assessed its feasibility for MICP as a preliminary step towards stabilizing loose beach sand in Sri Lanka. The results indicated that a strain belonging to Sporosarcina sp. isolated from inland soil demonstrated a satisfactory level of enzymatic activity at 25 °C and moderately alkaline conditions, making it a suitable candidate for target application. Elementary scale sand solidification test results showed that treated sand achieved an approximate strength of 15 MPa as determined by needle penetration device after a period of 14 days under optimum conditions. Further, Scanning Electron Microscopy (SEM) imagery revealed that variables such as grain size distribution, bacteria population, reactant concentrations and presence of other cations like Mg2+ has serious implications on the size and morphology of precipitated crystals and thus the homogeneity of the strength improvement.

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

Utilizing Enzyme-Induced Calcium Carbonate Precipitation (EICP) reinforcement technology has emerged as an innovative approach for soil improvement. In this study, kitchen waste eggshell powder was used as an additive material for EICP. The high external surface area and affinity for calcium ions of eggshell powder, which render it a suitable nucleation site for calcium carbonate precipitation. Experimental results demonstrate that the incorporation of eggshell powder, by increasing the number of nucleation sites and promoting calcium carbonate precipitation, reduces the inhibition of enzyme products, modulates the precipitation pattern of calcium carbonate, improves particle size distribution, and consequently significantly enhances the unconfined compressive strength of the samples. Furthermore, a neutral pH is achieved within the reaction system without the addition of any acid, thus preventing significant ammonia emissions. This underscores the potential of kitchen waste eggshells for recycling in biocement applications. [ABSTRACT FROM AUTHOR]

Microbial-induced carbonate precipitation (MICP) is an environmentally friendly approach that relies on the production of calcium carbonate by microorganisms to construct or reinforce coastal structures. In order to address the disadvantages of current coastal countermeasures techniques, MICP is a cost-effective solution that can be used to repair and restore coastal habitats damaged by human activities. The resulting structures formed through MICP are strong and durable, providing long-term protection against erosion and flooding caused by storms or rising sea levels. Biominerals, including calcium carbonate or calcium phosphate, are used to create complex composites with organic molecules by combining the strength of inorganic materials with the versatility and biocompatibility of organic macromolecules. It is of the utmost importance to investigate the functionality of MICP and scale up its deployment in various fields in order to thoroughly assess the instrument's application. Coastal erosion has been a severe concern in archipelagic countries. Therefore, this study explored the Miyazaki coast in Japan and the Yogyakarta coastline in Indonesia to minimize coastal erosion using MICP. The bacteria found in Miyazaki (Sporosarcina species) and the Yogyakarta coast (Pseudoalteromonas tetradonis) were used in the experiment. As a result, the sample treated with a gradual injection of the cementation solution achieved about 6 MPa UCS after 21 days of treatment. The objective were investigated the potential biotreatment with original sand materials and to evaluate the long-term durability under saturated conditions. For these purposes, the MICP-treated sand columns were subjected to series of compression tests and wet-drying (WD) durability analysis. [ABSTRACT FROM AUTHOR]