Concentration Limit Research Articles

Synovial fluid dual-biomarker algorithm accurately differentiates osteoarthritis from inflammatory arthritis.

Osteoarthritis (OA) prevalence increases as the population ages. Diagnosing osteoarthritis often occurs in the late stages when cartilage degradation is severe, making it difficult to distinguish from other types of arthritis. Accurate differentiation of primary osteoarthritis from other arthritic conditions is crucial for effective treatment planning. A new diagnostic test has been developed that uses a dual-biomarker algorithm to inform osteoarthritis diagnosis. Synovial fluid from patients with confirmed primary osteoarthritis showed elevated levels of cartilage oligomeric matrix protein. However, this biomarker alone could not distinguish primary osteoarthritis from other inflammatory conditions that also cause cartilage deterioration. Therefore, a combinatorial algorithm using cartilage oligomeric matrix protein and Interleukin-8 concentrations was developed to differentiate primary osteoarthritis from inflammatory arthritis. Clinical decision limits for cartilage oligomeric matrix protein concentration and the cartilage oligomeric matrix protein to Interleukin-8 ratio were established and validated using 171 human knee synovial fluid specimens. The osteoarthritis algorithm demonstrated clinical sensitivity and specificity of 87.0% and 88.9%, respectively. This is the first report of a biomarker test that can differentiate primary osteoarthritis from inflammatory arthritis with a high degree of accuracy.

Analysis on Spatial-temporal Characteristics and Driving Factors of PM2.5 in Heilongjiang Province in the Past 20 years

PM2.5 is an important indicator for measuring the degree of air pollution. Studying the space-time variation and the driving factors of spatial heterogeneity is important for controlling air pollution and improving regional air quality. Based on PM2.5 remote sensing data from 2000 to 2021, the Theil-Sen Median trend analysis, Mann-Kendall significant inspection, and spatial auto correlation were used to analyze the characteristics of space-time changes in PM2.5 concentration, and geographical detectors were combined with a multi-scale geographical weighted regression model to explore the key driver factor and its influence and direction of the impact and role of PM2.5 spatial differences. The results showed that： ① The average PM2.5 value of Heilongjiang Province was between 22.01 and 41 μg·m-3 from 2000 to 2021. From 2008 to 2015, the average PM2.5 value was higher than the secondary concentration limit （35 μg·m-3） of the "Environmental Air Quality Standard." The turning point of the PM2.5 concentration change that occurred in 2013 generally showed the trend of change and then a downward trend. Winter was the high incidence season for PM2.5 pollution. The PM2.5 concentration space was a distributed pattern in the south and north and the high-value zone was mainly based on Harbin, Daqing City, and the surrounding area. The low-value areas were distributed in the northern regions such as the Great Khingan Mountains Region and Heihe City. ② Factor detection results indicated that the average annual temperature was the most important driving factor that affected PM2.5 spatial differences. The remaining key driver factors were in turn： high-end, population density, average annual wind speed, land use, night lights, annual years precipitation, slope, annual relative humidity, and NDVI. Interactive detection showed that the interpretation of PM2.5 points after interaction was higher than a single factor after interaction, indicating that affecting PM2.5 spatial difference was the result of the common effect of each driver factor. The effect of natural factors was more obvious than that of social and economic factors. ③ The effect of different influence factors on PM2.5 had a significant spatial difference. The average annual temperature, average annual relative humidity, population density, and night lighting played a promotion effect on PM2.5 pollution and NDVI and land use played an inhibitory effect on PM2.5 pollution. PM2.5 was significantly different from the action role of various influencing factors and the average annual temperature, annual average wind speed, and NDVI impact scale were the smallest, with a variable bandwidth of 43； population density and land use impact scale were the largest, with a variable bandwidth of 140.

The Effect of Air Exchange Rate and Room Size on Dose Estimation of Partial Substitution of Tin Slag 2 on Fine Aggregate in Making Mortar in Buildings

Tin slag 2 is a by-product of the tin processing and smelting industry. Tin slag 2 contains radioactive from the uranium and thorium decay series with specific activity concentrations. The current condition of tin slag 2 is still stored in storage. This study aims to simulate using tin slag 2 as a partial substitute for fine aggregate in making mortar, used as a floor or wall plastering material. Dose analysis of the use of mortar–tin slag 2 using RESRAD-BUILD. Several radionuclides were measured in tin slag 2, such as 226Ra 5.72 Bq/gram, 228Th 14.29 Bq/gram, 228Ra 16.59 Bq/gram, and potassium 1.16 Bq/gram. According to the regulations, the activity concentration limit is 1 Bq/gram for the uranium and thorium decay series radionuclide and 10 Bq/g for the potassium. Simulations were performed using RESRAD-BUILD software with scenarios of 2 room sizes against one assumption of the building/air exchange rate. In 2 room size assumptions, namely 4x3x2.5 m and 4x5x2.8 m, the results showed that the larger the room size, the smaller the dose received. Assuming the same building exchange rate, because the sizes used are different, the amount of air exchanged will also be different and affect the dose received by the receptor. The challenge that must be considered is that the air exchange rate is greatly influenced by various factors such as design, ventilation systems, natural or mechanical, environmental conditions, etc. Keywords: tin, slag 2, partial, substitution, mortar

Determining Targets for Antiretroviral Drug Concentrations: A Causal Framework Illustrated With Pediatric Efavirenz Data From the CHAPAS-3 Trial.

Determining a therapeutic window for maintaining antiretroviral drug concentrations within an appropriate range is required for identifying effective dosing regimens. The limits of this window are typically calculated using predictive models. We propose that target concentrations should instead be calculated based on counterfactual probabilities of relevant outcomes and describe a counterfactual framework for this. The proposed framework is applied in an analysis including longitudinal observational data from 125 HIV-positive children treated with efavirenz-based regimens within the CHAPAS-3 trial, which enrolled children < 13 years in Zambia/Uganda. A directed acyclic graph was developed to visualize the mechanisms affecting antiretroviral concentrations. Causal concentration-response curves, adjusted for measured time-varying confounding of weight and adherence, are calculated using g-computation. The estimated curves show that higher concentrations during follow-up, 12/24 h after dose, lead to lower probabilities of viral failure (> 100 c/mL) at 96 weeks of follow-up. Estimated counterfactual failure probabilities under the current target range of 1-4 mg/L range from 24% to about 2%. The curves are almost identical for slow, intermediate and extensive metabolizers and show that a mid-dose concentration level of ≥ 3.5 mg/L would be required to achieve a failure probability of < 5%. Our analyses demonstrate that a causal approach may lead to different minimum concentration limits than analyses that are based on purely predictive models. Moreover, the approach highlights that indirect causes of failure, such as patients' metabolizing status, may predict patients' failure risk, but do not alter the threshold at which antiviral activity of efavirenz is severely reduced.

Thermodynamic Analysis of the Concentration Process of Solar Radiation

Extremely rarefied but high-temperature solar radiation energy is nowadays commonly concentrated to produce a high-temperature heat source. The article is a contribution to theoretical considerations on the process of concentration of solar radiation. The process of concentration of extraterrestrial solar radiation was subjected to thermodynamic analysis and the energetic, entropic and exergetic points of view were taken into account. An imaginary model of concentration was defined, which allowed the development of thermodynamic analyses of the concentration process. In the model, concentrated solar radiation irradiates the absorbing surface, the temperature of which is controlled by the intensity of cooling. The newly revealed values of temperature (7134 K) of the Sun&amp;apos;s surface and its energetic and exergetic emissivity (0.431 and 0426, respectively) were used in the analyses. With the use of model equations, the relationship between the ratio of radiation concentration, temperature and emissivity of the absorption surface, cooling intensity, absorbed heat, ambient temperature, and energy and exergetic efficiency of the concentration process was determined. Entropy analysis confirmed that the concentration limit temperature is equal to the temperature of the Sun&amp;apos;s surface. Examples of energy and exergetic balances of the concentration process, illustrated by band diagrams, showed the percentage share of energy and exergy fluxes. In contrast to the energy balance showing no energy loss, the exergy balance showed a significantly large loss of exergy due to the irreversibility of the process. The components of this irreversibility have been identified, which are the absorption of solar radiation and the much lower irreversibility of the emission of the heated surface.

Quantum dots based “fingerprint” markers with time-resolved luminescence for fuel labeling

The study examines the possibility of creating the luminescent “fingerprint” labels based on semiconductor quantum dots with different luminescence lifetimes. It is proposed to separate the spectra of different label components using time-resolved luminescence spectroscopy. The work produces luminescent labels consisting of two components: core-shell CdSe/CdS/ZnS quantum dots with the luminescence lifetimes in the nanosecond range and paramagnetic Cd0.9Mn0.1S/ZnS quantum dots, emitting for several hundred microseconds.It is shown that the luminescence of quantum dots is not quenched when they are dispersed in gasoline. The concentration limits of detection of indicators based on quantum dots are determined using luminescence spectroscopy, which were compared with previously studied analogs. Optimum ratios of different quantum dots in the composition of the indicator with bimodal luminescence are determined.

Accelerated Life Tests for Time-Dependent Response Characterization of Functionalized Piezoelectric Microcantilever-Based Gas Sensors

This article explores the accelerated lifetime test approach to characterize the time-dependent response of a piezoelectrically driven microcantilever (PD-MC) based gas sensor. The novelty here relies on demonstrating how accelerated lifetime tests can be useful to differentiate sensing mechanisms for non-linear gas sensors. The results show the determination of the sensor’s optimum operation time while maintaining result validity. The approach is demonstrated for 1,5-diaminopentane (cadaverine), a volatile organic compound (VOC) whose concentration in meat and fish products has been proven viable for determining the shelf life. A PD-MC functionalized with a cadaverine-specific binder was therefore incorporated into a hand-held electronic nose, and the response was found to be highly reliable within a specific resonance frequency shift, enabling the accurate prediction of meat and fish expiration dates. To identify the limits of detection in terms of cadaverine concentration and sensor lifetime, this study applies the results of accelerated life tests into a Weibull distribution analysis to extract the expected time to failure. For the accelerated life tests, a functionalized PD-MC was exposed to high concentrations of cadaverine, i.e., 252.3 mg/kg, 335.82 mg/kg, and 421.08 mg/kg, compared to the nominal concentration of 33 mg/kg observed in meat and fish samples. Furthermore, we demonstrate the differentiation of the response mechanisms of the system accruing from the concentration-dependent interaction of cadaverine with the binder. This enables the determination of the upper limit of the analyte concentration for a stable response. The findings suggest that the functionalized PD-MC sensor exhibits a linear and predictable response when exposed to a standard cadaverine concentration of 33 mg/kg for up to 93.01 min.

Assessment of trace organic chemicals in anaerobically digested sludge and their partitioning behaviour: Simultaneous Soxhlet chemical extraction and quantification via LC-MS/MS analysis

The increasing number of trace organic contaminants (TrOCs) detected in anaerobically digested sludge (ADS) is triggering increasing concern on its circular-economy reuse practices. A large scientific effort has been performed to define their concentration limits, partition behaviour, and innovative technologies for their removal, which require the definition of versatile and economically sustainable analytical methodologies. In this study, a Soxhlet extraction method coupled with LC-MS/MS analysis was developed to simultaneously determine 32 TrOCs in ADS, 11 of them being quantified in this matrix for the first time. The targeted TrOCs were selected based on the European Urban Wastewater Treatment Directive, and on their frequency of detection in municipal wastewater and/or sludge and chemical diversity. The use of methanol as solvent allowed good recovery efficiencies from ADS solid phase, with an extraction time of 3.5 h and without the need for subsequent clean-up procedures. The targeted LC-MS/MS method enabled high-sensitivity quantification of TrOCs in the liquid phase. At least 25 out of the 32 target compounds were detected in ADS samples from two wastewater treatment plants in Germany, providing their concentration data and highlighting the influence of TrOCs characteristics and sludge properties on contaminant partition coefficients (KD). The experimental outcomes highlight the versatility of the Soxhlet method, which is effective in extracting compounds characterized by diverse properties and structures, and opens new perspectives for the analysis of various substrates. This could support the European Sewage Sludge Directive, expanding its application to soils and cultivated foods and offering insights into TrOCs transfer among different substrates and their influence when used as fertilizer, aiding in the efficient definition of risk assessment methodologies and regulatory concentration limits.

Effect of antioxidant and adsorbent on the digestibility and digestibility of nutrients in broiler diets while reducing the risk of aflatoxicosis

Purpose: determination of the adsorbent toxin and antioxidant vitamin C on the digestibility and assimilation of nutrients in the composition of compound feed for broiler chickens with a tolerant level of aflatoxin B1.Materials and methods. The objects of the study were broiler chickens of the KOBB-500 cross. When setting up the experiment, the duration of 42 days, 4 groups of 100 heads each were formed from day-old chickens according to the principle of analog groups. The experimental birds were fed complete compound feeds (CF) based on corn, sorghum and fodder beans. The samples of compound feeds have a high chemical composition and the presence of mycotoxins. Upper limits of permissible concentrations (ULC) for aflatoxin B1 were established in all three types of feed grain. Therefore, they were mixed with safe mycotoxin additives using dispensers in the feed shop of the poultry enterprise. In this way, tolerable levels (no more than 0,25 mg/kg of feed) of the content of this mycotoxin in the composition of the PK fed to the experimental birds were achieved. Against the background of the conducted scientific and production experiment with the use of chromium oxide in the composition of compound feed (as an inert indicator) on chickens (aged 35-42 days) of comparable groups (5 heads from each group), we conducted an exchange (physiological) experiment. Based on the results of chemical analysis of the fed compound feed and excrements in the droppings of the experimental birds, the level of digestibility and assimilation of nutrients in the diet was calculated.Results. During the experiment, the leadership of the combined introduction of the adsorbent toxfin in the amount of 1500 g/t and ingredient C in the amount of 500 g/t of feed into complete feeds for broiler chickens with a tolerant level of aflatoxin B1 was established. As a result, compared to the birds of the control group, the chickens of the 3rd experimental group had significantly (р&lt;0,05) higher coefficients of digestibility of dry matter by 3,66%, organic matter by 3,90 %, crude protein by 3,63 %, fiber by 3.06% and NFE by 3,19 %, respectively. In terms of the degree of nitrogen assimilation (60,45 %), the result (51.45 %) and phosphorus (49,67 %) from the generally accepted amount with feed, the best indicators were also obtained in broilers of the 3rd experimental group, which reliably (р&lt;0,05) outperformed their control indicators for these indicators by 3,74 %, 2,91 % and 2,45 %, respectively.

OPTIMIZATION OF LC-MS/MS METHOD FOR THE SIMULTANEOUS DETERMINATION OF METFORMIN AND ROSIGLITAZONE IN HUMAN PLASMA WITH BOX-BEHNKEN DESIGN

Objective: The objective of this study was to develop a robust Liquid Chromatography – Tandem Mass Spectrometry (LC-MS/MS) methodology for the precise quantification of metformin and rosiglitazone in human plasma. Methods: A Design of Experiments (DOE) framework was utilized, specifically employing a Box-Behnken experimental design, to optimize critical parameters such as Capillary voltage, Cone voltage, Desolvation temperature, and Collision energy. Sample preparation involved protein precipitation using acetonitrile, simplifying the procedure. Chromatography was performed with a mobile phase of 0.1% formic acid and acetonitrile (60:40 V/V) to enhance sensitivity and reproducibility. Quantification was achieved through Multiple Reaction Monitoring (MRM) of the transition’s m/z 130.1 → m/z 60.1 for metformin, m/z 358.2 → m/z 134.9 for rosiglitazone, and m/z 206.3 → m/z 59.9 for phenformin. The methodology was validated according to regulatory guidelines. Results: The developed methodology demonstrated selectivity, linearity, accuracy, precision, recovery, and stability. The calibration curve showed linearity over the concentration range of 5 ng/ml to 1000 ng/ml for metformin and 1.5 ng/ml to 300 ng/ml for rosiglitazone. Accuracy and precision were within acceptable limits across calibration and quality control standards. Assessments of extraction recovery and matrix effects confirmed the robustness of the extraction procedure, with negligible interference from plasma components. Stability studies indicated that the method maintained acceptable limits for metformin and rosiglitazone concentrations under various storage and handling conditions. Conclusion: The validated Liquid Chromatography – Tandem Mass Spectrometry (LC-MS/MS) methodology provides a reliable and accurate platform for the quantification of metformin and rosiglitazone in human plasma. This method shows potential applications in pharmacokinetic studies and clinical research, ensuring consistent performance in routine analysis.

Nano‐Patterned CuO Nanowire Nanogap Hydrogen Gas Sensor with Voids

AbstractHydrogen (H2) is increasingly employed in industrial applications, such as developing hydrogen fuel cells for vehicles and power plants. However, H2 explodes at a concentration limit of 4%, necessitating the development of ultrasensitive hydrogen sensors capable of early‐stage detection of hydrogen leaks. In this study, nano‐patterned polycrystalline cupric oxide (CuO) nanowire array nanogap gas sensors with voids are fabricated using electron‐beam lithography and ex situ oxidization by annealing, which could detect 5 ppb H2 and show response and recovery times of less than 10 s without a baseline shift. Combining a pre‐H2 annealing process in Ar/H2 for Cu nanowires and a low‐rate oxidation process enhances the crystallinity of CuO nanowires, facilitating the preparation of polycrystalline CuO nanowires with voids, which is a significantly practical approach for the improvements of gas sensing properties. Response and recovery times of &lt;10 s can be obtained for a gap separation of ≈30 nm. These improvements are discussed based on a high electric field of ≈1.3 MV cm−1. The relationship between the normalized response and H2 concentration is discussed based on the power law. This paper presents highly reliable and fast H2 sensors without a baseline shift to meet the demands of the hydrogen industry.

A room-temperature NO2 gas sensor based on Zn2+ doped Cu2O/CuO composites with ultra-high response

Metal oxide semiconductors (MOS) have attracted increasing interest in gas sensors recently due to their exceptional design flexibility and superior gas sensing capabilities. However, the high operating temperatures and reliance on light activation in MOS-based gas sensors limit their potential applications. In this work, the Zn2+ doped Cu2O/CuO composites were successfully fabricated by one-step hydrothermal method for the detection of NO2 gas at room temperature. The experimental results show that the optimal Zn-Cu2O/CuO composite presents responses that are 2.9, 3.4, 3.1 times higher than those of the pure Cu2O/CuO composite to 10, 5 and 1 ppm NO2. Additionally, the response and recovery times are shortened by factors of 3.1 and 1.4, respectively. Notably, the detection limit of the Zn-Cu2O/CuO composite is 2 ppb at room temperature, significantly below China's annual average NO2 concentration limit of ∼18 ppm. Furthermore, the Zn-Cu2O/CuO based sensor demonstrates the great selectivity, repeatability and long-term stability for NO2 detection. The gas sensitivity enhancement mechanism is thoroughly discussed. This result provides a new approach for the effective detection of ppb-level NO2 by CuO-based gas sensing materials at room temperature.

Safety, efficacy and immunogenicity of aerosolized Ad5-nCoV COVID-19 vaccine in a non-inferiority randomized controlled trial

This phase 3, observer-blinded, non-inferiority randomized trial (ClinicalTrials.gov: NCT05517642), conducted from September 2022 to May 2023 at three Malaysian sites, involved 540 adults previously vaccinated with three COVID-19 doses. Participants were randomized 1:1 to receive either one dose of inhaled Recombinant COVID-19 Vaccine (Ad5-nCoV-IH) or intramuscular tozinameran (BNT-IM). The study assessed safety, vaccine efficacy (VE) and immunogenicity against SARS-CoV-2 variants. The primary outcome was the non-inferiority of anti-spike protein receptor-binding domain (S-RBD IgG) antibodies, with a 97.5% confidence interval lower limit for the geometric mean concentration (GMC) ratio >0.67. Ad5-nCoV-IH showed lower immunogenicity than BNT-IM, with a GMC ratio of 0.22 and a seroconversion rate difference of -71.91%. Adverse drug reactions (ADRs) were less frequent with Ad5-nCoV-IH (39.26%) compared to BNT-IM (64.68%). No serious vaccine-related adverse events were reported. Both vaccines had comparable efficacy against COVID-19 variants. This study was funded by Tianjin Biomedical Science and Technology Major Project.

Effect of inorganic salt composition on strength, microstructure and leaching toxicity of coal-based solid waste backfill materials

This study explores the potential of coal-fired slag, desulfurized gypsum and modified magnesium slag as cementing agents for coal-based solid waste backfill materials. Inorganic salts like CaCl2, Na2SO4 and Na2SiO3 were used as excitants to investigate their combined impact on the mechanical properties, microstructure and leaching risk of hazardous elements from the coal-based solid waste backfill materials. The findings show that the addition of inorganic salt boosts the alkalinity within the liquid-phase reaction system. This disrupted the hydration-blocking membrane, accelerating the dissolution and reaction rate of the silica-alumina mineral components within the cementitious material. Concurrently, the inorganic salt ions consumed the early alkaline hydration products, destroying the hydration reaction equilibrium and facilitating the formation of hydration products like AFt, C-S-H gel, C-A-S-H gel, and Friedel's salt. This increase in the solid-phase volume content and microscopic densities in the reaction system improved the early mechanical properties of the coal-based solid waste backfill materials. Additionally, after a 28-day curing period, the leaching concentration of deleterious elements in the coal-based solid waste backfill material containing inorganic salt components was below the permissible concentration limit of the Class III groundwater quality standard. This eco-friendly backfill material is promising for mine backfilling, a potential substitute for traditional cement-based backfill material.

Developing alkali-activated controlled low-strength material (CLSM) using urban waste glass and red mud for sustainable construction

Using industrial waste in controlled low-strength material (CLSM) offers many benefits and addresses waste management issues. However, identifying optimal CLSM design while balancing environmental impacts and engineering properties poses a notable challenge. Herein, new alkali-activated CLSM formulations based on urban waste glass and red mud (RM) are proposed for the first time with systematic investigations into the material properties and sustainability. The formulations involve the ternary blends of slag, glass powder (GP) and RM as the binders and crushed glass as aggregate. Our observations show RM has a clay-like texture with complex crystalline phases rich in Al and Fe. Increasing the proportion of RM to GP notably decreases the flowability, extends the setting time and impairs the mechanical properties. Nevertheless, red mud demonstrates a crucial role of reducing bleeding level especially for the mixtures with high proportions of glass aggregate. The standard leachate tests as per toxicity characteristic leaching procedure (TCLP) show the heavy metals leached from the CLSM are below the concentration limits and exhibit low mobility. The microstructural and thermodynamic analyses reveal the precipitation of calcium-(sodium-)aluminosilicate hydrate (C-(N-)A-S-H) as the major binding material. The reactive Fe and Al in red mud most probably contribute to the formation of hydrogarnet phases. Moreover, the suggested CLSM formations typically exhibit reduced carbon emissions and lower costs compared to the traditional CLSM produced with cement and fly ash, underlining their environmental sustainability and cost-effectiveness. This study provides a potential guideline for the flowable fill construction in the regions with bauxite producers.

Determination of 4-methylimidazole and 2-acetyl-4-tetrahydroxy-butylimidazole in caramel color and products by liquid chromatography-mass spectrometry

The simultaneous determination of 4-MEI and THI in caramel and products by LC-MS/MS was developed with several advantages of simplicity, selectivity, and high sensitivity. Chromatographic separation was performed using a C18 column (100 × 2.1 mm, 1.7 μm), with a mobile phase consisting of ammonium formate pH = 4 and acetonitrile containing 0.1% formic acid employing a gradient elution mode. The analytes were detected using an MS/MS double mass spectrometer with an ESI+ ionization source. Samples were cleaned and enriched on a SPE MCX column. Method validaion resulted in a linear range of 5.0 - 500 ppb for 4-MEI, and 1.0 - 500 for THI, with LODs of 0.30 g/kg for THI and 1.5 μg/kg for 4-MEI, and LOQs of 1 μg/kg for THI and 5 μg/kg for 4-MEI. Repeatability and reproducibility for 4-MEI ranged from 2.9% to 9.1% and 2.9% to 11.8%, respectively, and for THI from 3.5% to 9.4% and 4.8% to 11.5%, respectively. Recovery rates for with 4-MEI and THI met AOAC's requirements, ranging from 82.7% to 106.4% and 87.2% to 109.7%, respectively. Application of the analytical method for 24 market products, including caramel, beverages, condiments, and cakes, showed that the 4-MEI and THI concentrations in consumer products were within the permissible limits, while pure caramel samples exceeded the permissible limits for THI concentrations.

Evaluation of encapsulated Bacillus subtilis bio-mortars for use under acidic conditions

This research aimed to examine the effects of an acidic environment on the mechanical properties and durability of bio-mortar (BM) encapsulated with Bacillus subtilis bacteria, in comparison to normal mortar (NM). The results at 28 days indicated that both 3% and 6% HCl significantly increased the compressive strength of the BM by 25% and 50%, respectively, compared with that of the NM. However, when 11% HCl was introduced, the compressive strength of the BM decreased to 50% lower than that of the NM. Furthermore, the water absorption rate of the BM was 33% lower than that of the NM. The mass loss for both 3% and 6% HCl was comparable, whereas at 11% HCl, BM experienced a mass loss that was 68% greater than that of NM. These findings suggest that with 3% and 6% HCl, the microbially induced calcium carbonate precipitation (MICP) process effectively generated CaCO3, which filled the pores and enhanced the structural integrity of the BM, leading to improved compressive strength and durability. Conversely, at 11% HCl, the MICP benefits in BM were diminished due to adverse environmental conditions that negatively affected the bacterial cells, highlighting the limitations of the HCl concentration for optimizing MICP efficiency in mortar.

A selective diesel vehicle ban’s impact on NO2 concentrations in Munich: a quasi-experimental study

Abstract Background The European Union’s current NO2 concentration limit of 40 μg/m³ is regularly exceeded in Munich, Germany. This limit is likely to be reduced towards the WHO recommended target of 10 μg/m³. In response, the city enacted a selective ban on older diesel vehicles, specifically those categorized as Euro 4 or older, within the current low-emission zone in February 2023. Our study examined how Munich’s selective ban on diesel vehicles impacted NO2 levels, concentrating on the six-month period after its introduction. Methods We employed a synthetic control approach in the primary analysis and a controlled interrupted time series approach in the secondary analysis. These quasi-experimental methods establish a ‘counterfactual’ no-intervention scenario, allowing for comparison with the actual observed scenario and estimation of the impact of the intervention. Historical data from monitoring stations within and outside the low-emission zone from 2014 to 2022 were utilized as controls, while potential confounders were considered. Results NO2 concentrations within Munich’s low-emission zone decreased across the study period. Effects of the selective diesel vehicle ban at monitoring stations within the low-emission zone were minimal, with wide confidence intervals indicating uncertainty. At Landshuter Allee, the average intervention effect was -2.67 μg/m3 (95%-CI = [-12.72; 7.38]), at Stachus it was -2.74 μg/m3 (95%-CI = [-9.91; 4.42]) and at Lothstrasse, it was -1.03 μg/m3 (95%-CI = [-7.75; 5.69]). The secondary analysis confirms these findings. Conclusions Munich’s selective diesel vehicle ban had limited effects in reducing NO2 concentrations. Factors such as its narrow focus on Euro 4 diesel vehicles, numerous exemptions, and unclear enforcement may explain this outcome. Comprehensive strategies and continuous monitoring and evaluation are crucial for effectively addressing urban air pollution and protecting public health. Key messages • Munich’s selective diesel vehicle ban had minimal effects on reducing NO2 levels, possibly due to its narrow scope, many exemptions, and unclear enforcement. • Current guidelines and court rulings signal the need for more effective solutions beyond selective bans, emphasizing the importance of well-designed interventions and rigorous evaluation.

Exploring the Lower Limit of Target Concentration in Capture-SELEX Using Guanine as a Model Target.

During an aptamer selection, using a lower target concentration may result in aptamers with a higher binding affinity. Consequently, this begs the question of whether there is a lower limit for target concentration. In this work, we conducted three aptamer selections using 5 μM, 500 nM and 50 nM guanine as the targets, respectively. Successful enrichment of the same guanine aptamers was achieved at both 5 μM and 500 nM guanine, but not with 50 nM. Using 5 μM guanine, the aptamer was enriched in eight rounds of selection, compared to that for 500 nM, which was accomplished in 17 rounds. We discuss the relation of optimal target concentration to the observed Kd value of the resulting aptamers, of which the highest affinity aptamer had a measured Kd of 200 nM. Additionally, we investigated the binding of the aptamers through mutation studies, revealing a critical cytosine. Mutating this cytosine to a thymine switched the selectivity from guanine to adenine, which is reminiscent of the guanine riboswitch. This study revealed a limit in using low target concentration, and the insights described in this article will be useful for guiding the choice of target concentration during capture-SELEX.

High temperature co-processing of stainless-steel slag and red mud: Towards a selective Cr immobilization and harmless treatment

Stainless-steel slag and red mud are bulk metallurgical wastes, which are difficult to reuse due to the complex composition and high environmental risk. To realize their harmless and resource utilization, a collaborative treatment of the stainless-steel slag (AOD slag) and red mud at high temperature was proposed in this study. The influence of the stainless-steel slag to red mud ratio on spinel phase precipitation and crystallization, Cr enrichment and immobilization in the mixed slags were systematically investigated. The results demonstrated that when the stainless-steel slag to red mud ratio was 6:4, the enrichment degree of Cr in spinel phase was 94.12 wt%, and the precipitation amount of spinel reached the highest, 20.98 wt%. In this case, only small amounts of other mineral phases existed, the crystal particle size of spinel phase was larger, and the self-wrapped spinel phases were formed in the stage of cooling. The outer Cr-poor spinel could avoid the abrasion and erosion of the inner Cr-rich spinel in the subsequent physical separation process, thus reducing the risk of Cr6+ dissolution. In the toxic leaching test, the total Cr concentration leached from the mixed slag (stainless-steel slag to red mud ratio was 6:4) was far lower than the national leaching concentration limit of Cr-related ions. The Cr and Fe-rich spinel phases separated from the mixed slag of stainless-steel slag and red mud can be used as the raw material for the production of stainless steel, while the residual Cr-poor slag rich in Ca, Si and Al can be applied in the field of construction.