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Protocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

Microbially induced calcium carbonate precipitation (MICP) is an innovative biocementation technique that facilitates the formation of calcium carbonate within a pore network. Initially gaining prominence in the field of geotechnical engineering, MICP has attracted significant attention since its inception (the last three decades) and expanded its reach across various engineering disciplines. Examples include rock mechanics, geology and the oil and gas industry fields through the generation of rock-like specimens, and plugging of fractures, in civil and architectural engineering and material science for concrete repair, protection, and for self-healing of building materials, and in environmental engineering for the study of biomimetic materials. In response to this burgeoning interest, the current paper aims to present a comprehensive review of the main biochemical mechanisms underlying MICP (bacterial ureolytic activity, reactions duration and settling times, and chemical solution properties), their direct relevance to altering hydraulic and mechanical properties, both at the microscale and macroscale responses, and the precipitation mechanisms, particularly in relation to water resources and hydrology applications. Four main categories of relevant applications are identified, namely, the groundwater and soil remediation, the applications related to the generation of a low hydraulic conductivity barrier, those related to gaining cohesion, and the applications related to fluid flow studies in artificially generated porous media. Moreover, this comprehensive review not only aims to identify the existing applications of MICP within hydrological fields but also strives to propose novel and promising applications that can further expand its utility in this domain. Along with the investigation of the potential of MICP to revolutionize water resources and hydrology, it is imperative to delve deeper into its environmental implications to ensure sustainable and ecologically responsible implementation.

IntroductionPostoperative cardiac injury, encompassing myocardial infarction (MI) and myocardial injury after non-cardiac surgery (MINS), is a major perioperative complication associated with substantial morbidity and mortality. While numerous prediction models have been developed using traditional statistical and machine learning approaches, their comparative performance, calibration quality and methodological rigour remain unclear. This protocol outlines a systematic review and meta-analysis to comprehensively evaluate multivariable risk prediction models for postoperative cardiac injury in adults undergoing non-cardiac surgery.Methods and analysisFollowing Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines, this PROSPERO-registered systematic review will search PubMed, Embase, Web of Science, Cochrane Library, Scopus, grey literature and trial registries for studies developing, validating or updating multivariable prediction models for postoperative cardiac injury (MI or MINS) occurring within 72 hours of non-cardiac surgery. Two reviewers will independently extract data and assess quality using CHARMS (Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies) and PROBAST (Prediction Model Risk of Bias Assessment Tool) tools. The primary outcome is discriminative performance (area under the receiver operating characteristic curve), with calibration metrics and diagnostic accuracy measures as secondary outcomes. Random-effects meta-analyses will pool performance estimates for models validated in multiple cohorts. Heterogeneity will be explored through subgroup analyses and meta-regression, examining factors including model methodology (regression-based vs machine learning), predictor types and validation contexts. Sensitivity analyses will test the robustness of findings.Ethics and disseminationEthical approval is not required for this study, as it is a systematic review and meta-analysis based on previously published data.PROSPERO registration numberCRD420251041628.

Increased evidence shows that gut microbiota acts as the primary regulator of the liver; however, its role in sepsis-related liver injury (SLI) in the elderly is unclear. This study assessed whether metformin could attenuate SLI by modulating gut microbiota in septic-aged rats. Cecal ligation and puncture (CLP) was used to induce SLI in aged rats. Fecal microbiota transplantation (FMT) was used to validate the roles of gut microbiota in these pathologies. The composition of gut microbiota was analysed by 16S rRNA sequencing. Moreover, the liver and colon tissues were analysed by histopathology, immunofluorescence, immunohistochemistry, and reverse transcription polymerase chain reaction (RT-PCR). Metformin improved liver damage, colon barrier dysfunction in aged SLI rats. Moreover, metformin improved sepsis-induced liver inflammation and damage under gut microbiota. Importantly, FMT assay showed that rats gavaged with faeces from metformin-treated SLI rats displayed less severe liver damage and colon barrier dysfunctions than those gavaged with faeces from SLI rats. The gut microbiota composition among the sham-operated, CLP-operated and metformin-treated SLI rats was different. In particular, the proportion of Klebsiella and Escherichia_Shigella was higher in SLI rats than sham-operated and metformin-treated SLI rats; while metformin could increase the proportion of Bifidobacterium, Muribaculaceae, Parabacteroides_distasonis and Alloprevitella in aged SLI rats. Additionally, Klebsiella and Escherichia_Shigella correlated positively with the inflammatory factors in the liver. Our findings suggest that metformin may improve liver injury by regulating the gut microbiota and alleviating colon barrier dysfunction in septic-aged rats, which may be an effective therapy for SLI.

A deep understanding of multipath characteristics is essential to design signal simulators and receivers in global navigation satellite system applications. As a new constellation is deployed and more applications occur in the urban environment, the statistical multipath models of navigation signal need further study. In this paper, we present statistical distribution models of multipath time delay, multipath power attenuation, and multipath fading frequency based on the experimental data in the urban canyon environment. The raw data of multipath characteristics are obtained by processing real navigation signal to study the statistical distribution. By fitting the statistical data, it shows that the probability distribution of time delay follows a gamma distribution which is related to the waiting time of Poisson distributed events. The fading frequency follows an exponential distribution, and the mean of multipath power attenuation decreases linearly with an increasing time delay. In addition, the detailed statistical characteristics for different elevations and orbits satellites is studied, and the parameters of each distribution are quite different. The research results give useful guidance for navigation simulator and receiver designers.

Microbially induced calcium carbonate (CaCO3) precipitation (MICP) has been extensively studied for soil improvement in geotechnical engineering. The quantity and size of calcium carbonate crystals affect the strength of MICP-treated soil. In this study, microfluidic chip experiments and soil column experiments were conducted to optimize MICP treatment protocols for effective strength enhancement of MICP-treated sandy soils. The microscale experiments reveal that, due to Ostwald ripening, longer injection intervals allow crystals to dissolve and reprecipitate into larger crystals regardless of the concentration of cementation solution. Even though a cementation solution input rate of 0.042 mol/l/h is sufficient to maintain a high chemical transformation efficiency, a further reduction in the input rate by about four times resulted in an increase in the size of crystals produced by the end of treatment from about 40 to 60 μm. These findings were applied in soil column experiments. Results showed that significantly larger crystals and higher soil strength were achieved when the normalized rate of cementation solution injection was reduced from 0.042 to 0.021 mol/l/h. Crystal size and soil strength increased slightly more when the normalized input rate was further reduced from 0.021 to 0.010 mol/l/h. This study demonstrates how data from microscale microfluidic experiments that examine the effects of injection intervals and concentration of cementation solution on the properties of calcium carbonate crystals can be used to optimize MICP treatment in macroscale sand soil column experiments for effective strength enhancement.

Microbially induced carbonate precipitation (MICP) involves a series of bio-geochemical reactions whereby microbes alter the surrounding aqueous environment and induce calcium carbonate precipitation. MICP has a broad range of applications, including in situ soil stabilization. However, the reliability of this process is dependent on a number of environmental conditions. In particular, bacterial growth, urease activity and precipitation kinetics all depend on temperature. Batch test and microfluidic chip experiments were performed in this study to investigate the effects of temperature on bacterial density and activity and the MICP processes occurring at different temperatures (4–50 °C). Spatial and temporal variations in the formation and development of calcium carbonate precipitates, including their amount, type, growth rate, formation and deformation characteristics, were monitored. Results show that different types of calcium carbonate precipitates with varying sizes and quantities were produced by varying the temperature. Low temperature (4 °C) did not reduce urease activity, but limited the final amount of cementation; low temperature reduced bacterial growth and attachment ratio, as well as calcium carbonate precipitation rate. High-temperature (50 °C) conditions significantly reduced urease activity within a short period of time, while a repeated injection of bacteria before every two injections of cementation solution increased the final amount of cementation. The findings made from this paper provide insight into how MICP processes vary across a range of temperatures and could be valuable for optimizing the MICP process for different applications.

Boron is a promising fuel, but its oxide layer impedes combustion. Alloying boron with other high-energy metals can significantly enhance its combustion performance. In this study, we sintered highly reactive lithium-containing Mg-Al-Li-B alloys using magnesium, aluminum–lithium alloy, and boron powder as raw materials. The effects of sintering temperature and holding time on the microstructure were investigated, and the combustion heat value and oxidation resistance of the alloy were tested. Results indicate that sintering temperature significantly influences phase formation: increasing temperature boosts phase content while reducing metallic phases, with 1100 °C identified as the optimal sintering temperature. Holding time had no discernible impact on the phase composition or combustion heat value of the sintered alloy. Alloying enhances material density, thereby increasing volumetric heat value. Thermal oxidation performance tests demonstrate that Li addition significantly lowers the alloy’s oxidation reaction temperature and activation energy, enhancing its reactivity. This high-heat-value, highly reactive alloy holds significant potential for application in pyrotechnics and propellants.

Background Partial hepatectomy (PH) may increase the risk of myocardial injury after non-cardiac surgery (MINS), a complication associated with substantial perioperative morbidity and mortality. Direct comparisons of MINS incidence between PH and other major abdominal surgeries (MAS) remain limited. This study evaluated whether PH confers greater risk of postoperative MINS compared with other MAS. Methods We conducted a retrospective propensity score-matched cohort study using the INSPIRE database. Adult patients undergoing PH or other MAS between 2011 and 2020 were identified. After 1:2 propensity score matching to minimize confounding, 163 PH patients were compared with 267 matched controls. The primary outcome was MINS incidence. Secondary outcomes included myocardial infarction, heart failure, in-hospital mortality, ICU admission, and hospital length of stay. Results Following propensity matching, PH patients exhibited significantly higher MINS incidence than controls (44.2% vs. 34.5%; OR = 1.51, 95% CI: 1.01–2.24, P  = 0.044). This association was particularly marked in overweight patients, among whom MINS occurred in more than half of PH cases versus approximately one-quarter of controls (52.3% vs. 26.9%; OR = 2.97, 95% CI: 1.37–6.45, P  = 0.006). No significant differences emerged in myocardial infarction, heart failure, in-hospital mortality, ICU admission, or hospital length of stay between groups. Conclusion Partial hepatectomy is associated with significantly increased risk of postoperative myocardial injury compared with other major abdominal procedures, particularly among overweight patients.

Background Recent studies have revealed that CD8 + T cells can be activated via genetic upregulation of HIF-1α, thereby augmenting antitumor effector functions. HIF-1α upregulation can be attained by inhibiting HIF-prolyl hydroxylase (HIF-PH) under normoxic conditions, termed pseudohypoxia. This study investigated whether pseudohypoxia induced by HIF-PH inhibitors suppresses Microsatellite stable (MSS) colorectal cancer (CRC) by affecting tumor immune response. Methods The HIF-PH inhibitors Roxadustat and Vadadustat were utilized in this study. In vitro, we assessed the effects of HIF-PH inhibitors on human and murine colon cancer cell lines (SW480, HT29, Colon26) and murine T cells. In vivo experiments were performed with mice bearing Colon26 tumors to evaluate the effect of these inhibitors on tumor immune responses. Tumor and spleen samples were analyzed using immunohistochemistry, RT-qPCR, and flow cytometry to elucidate potential mechanisms. Results HIF-PH inhibitors demonstrated antitumor effects in vivo but not in vitro. These inhibitors enhanced the tumor immune response by increasing the infiltration of CD8 + and CD4 + tumor-infiltrating lymphocytes (TILs). HIF-PH inhibitors induced IL-2 production in splenic and intratumoral CD4 + T cells, promoting T cell proliferation, differentiation, and immune responses. Roxadustat synergistically enhanced the efficacy of anti-PD-1 antibody for MSS cancer by increasing the recruitment of TILs and augmenting effector-like CD8 + T cells. Conclusion Pseudohypoxia induced by HIF-PH inhibitors activates antitumor immune responses, at least in part, through the induction of IL-2 secretion from CD4 + T cells in the spleen and tumor microenvironment, thereby enhancing immune efficacy against MSS CRC.