Dilution Effect Research Articles

Determining diagnostic sensitivity loss limits for sample pooling in duplex rtPCR surveillance testing: Theileria orientalis and Anaplasma marginale.

To expand surveillance testing capacity through sample pooling, a thorough understanding is needed of how sample dilution through pooling affects the sensitivity of candidate assays. We validated a robust and representative framework for assessing the dilution effect of sample pooling using duplex rtPCR surveillance of Theileria orientalis and Anaplasma marginale, both of which are causative agents of severe anemia in cattle and a serious threat to the cattle industry in Virginia and many other states. We used 200 known-positive samples with Ct values representative of typical surveillance results in a series of pools in which we re-tested each sample individually, followed by each sample diluted in equal volumes with negative samples to make pools of 2, 4, 6, 8, and 10 total samples. We compared the Ct values of the individual positives with the Ct values of each pool size to determine if Ct values increase past the limit of detection in the 45-cycle assay. We observed a maximum of 2% sensitivity loss (no more than 2 of 100 samples returned a false-negative result) for both T. orientalis and A. marginale during the pooling series, with lower-than-expected average Ct increase and sensitivity loss. We conclude that pooling up to 10 samples would be acceptable for regional surveillance of T. orientalis and A. marginale using our rtPCR assay. The described strategy is applicable to validate pooling for a wide range of single and duplex rtPCR assays, which could expand efficient disease surveillance.

Effect of dilution and Lewis number of the fuel in the fuel-air mixture on the heat flux during flame wall interaction (FWI)

Most combustion systems where flame is bounded by walls encounter Flame-wall interactions (FWI). Heat losses during FWI are in the magnitude of MW/m2 leading to concern about inefficiency, and thermal stresses. Hence, FWI is a topic of significant interest. With the goals of climate change pushing us toward renewable fuels with least carbon emissions, it is imperative to understand the FWI of renewable fuels like hydrogen-air mixture. In this study, FWI in a head-on-quenching configuration is carried out in a constant volume chamber. High-speed surface temperature measurement is carried out to compute instantaneous wall heat flux. Adding inert diluents to methane-air mixtures, the effect of dilution on the peak of heat flux during FWI is studied. Dilution affects the peak of heat flux predominantly by changing the adiabatic flame power of the fuel-air mixture. Furthermore, a large variation in flame power is carried out by changing the dilution fraction in the methane-air mixture to quantify its effect. It is found that the peak of heat flux and non-dimensional heat flux follows a nonlinear decrease with an increase in flame power. Knowing this effect, FWI of three different fuels, that is, methane, hydrogen, and a mixture of acetylene and hydrogen, having different Lewis numbers ( Le) of fuel in a fuel-oxidizer mixture are studied at equivalent flame power. This comparison shows that FWI of hydrogen-air mixtures in HOQ configuration have a lower peak of heat flux compared to other fuels which may be due to the preferential diffusion of hydrogen-air mixture.

Emissions and Flame Stability Assessment of Hydrogen Addition and Air Dilution in a Micro Gas Turbine Combustor Using 0D/1D Modeling by Chemical Reactor Network

Abstract Hydrogen emerges as a promising fuel for clean and sustain- able electricity production when utilized in micro gas turbines (mGTs). However, some challenges linked to hydrogen usage must be overcome as its high reactivity can lead to increased NOx emissions and flame instabilities. Literature suggests that combustion air humidification and/or exhaust gas recirculation (EGR) may be methods to reduce this reactivity. However, these measures are limited due to the small operating range of the mGT combustor. In this context, a 20 kWth mGT combustor is investigated un- der various inlet conditions to assess the effect of EGR towards increased flame stability and emission control when operating under hydrogen-enriched methane firing, using a Chemical Re- action Network (CRN) model. The CRN modeling is a fast and low computational complexity tool to model combustion perfor- mance and emissions by representing complex reactive flow fields through idealized reactor models, leading to reduced computa- tional costs. This study examines partial load conditions, fuel compositions, and the effect of combustion air dilution through EGR. The CRN model of the combustion process is designed based on combustion zones extracted from the main flow fields with similar thermo-chemical states from CFD, while emission predictions are experimentally validated for different operating points. Predicted NOx and CO emissions by the proposed CRN model show an acceptable agreement with the experimental data at high power loads. However, its accuracy diminishes for loads below 70% due to the variability in model tuning parameters across different loads, whereas the

Ozone Doping and Negative Temperature Response in the Explosion Limits of Ethylene-Oxygen Mixtures.

In this work, effects of ozone (O3) addition on ethylene-oxygen (C2H4-O2) mixtures are computationally studied through the explosion limit profiles. The results show that the addition of minute quantities of ozone (with a mole fraction of 0.06% in the oxidizer) shifts the explosion limit of the C2H4-O3-O2 mixtures to the low-temperature regime. Further increases in the ozone concentration gradually strengthen the negative temperature coefficient (NTC) behavior at the second limit. That is because the explosion limit is primarily controlled by the ethylene ozonolysis reaction, and both the sensitivity analysis and chemical reaction rate perturbation method reveal specific kinetic reasons. Furthermore, it is shown that with the increasing equivalence ratio, the explosion limit curve with minute ozone addition rotates counterclockwise around a crossover point, while the explosion limit curve becomes complicated and the NTC behavior appears on the second limit with larger quantities of ozone addition. Furthermore, the effects of dilutions of nitrogen (N2), argon (Ar), carbon dioxide (CO2), and water (H2O) on the explosion limits are also studied. To elucidate the different wall elimination effects of different explosion limit regimes, the impacts of surface reactions of six radicals (H, O, OH, HO2, H2O2, and HCO) have been examined and the dominant radicals are found to be H and HO2. The H radicals significantly influence the first explosion limit, while the HO2 radicals impact the entire explosion limit.

Enhancing Iron and Zinc Uptake in Spring Wheat Through Commercial Arbuscular Mycorrhizal Fungi Inoculation under Different Soil Phosphorus Addition Levels

Improving the concentrations and bioavailability of micronutrients, especially iron (Fe) and zinc (Zn), in crop grains is important to alleviate their deficiencies in humans. Inoculating crops with arbuscular mycorrhizal fungi (AMF) can potentially enhance soil nutrient supply and crop yield, but the effectiveness is influenced by soil factors, particularly soil phosphorus (P) availability. A greenhouse pot experiment was conducted to evaluate the effect of a commercial AMF product on spring wheat (Triticum aestivum L.) yield and grain concentrations of Zn and Fe under different soil P addition levels (0, 5 and 20 mg P kg-1 dry soil). Results showed that AMF inoculation significantly increased root colonization rate of wheat across all P addition levels. Wheat growth, as evidenced by dry weights of shoot and grain, was significantly enhanced by AMF and high P addition treatments. AMF inoculation did not affect grain Zn concentration, but significantly increased grain Fe concentration compared to the un-inoculated control. As expected, P addition resulted in a significant reduction in grain concentrations of Fe and Zn, primarily due to a growth dilution effect. An integrated analysis using the radar plot concludes that AMF inoculation is most effective in increasing crop yield and grain micronutrient concentrations when soil P levels are low. Importantly, while adequate P supply is crucial for maintaining crop productivity, it may decrease grain micronutrient availability without complementary strategies.

Hydrochemical Characterisation of the Basement Aquifer with a Focus on the Origin of Nitrate in the Highly Urbanised Niamey Region, SW of Niger

This study investigated the basement aquifer beneath the urbanised city of Niamey and the agricultural fields of Kollo, SW of Niger. During the observation period spanning from 2021 to 2023, groundwater and surface water samples were collected for analysis of major ions and the stable isotopes oxygen-18 and deuterium (δ18O and δ2H) of water. To trace the origin of high nitrate concentrations (NO3−) found in several observation and drinking water wells in both areas, δ15N and δ18O isotope values of NO3− were analysed in groundwater and eluted soil samples. The observed hydrochemical patterns mainly reflect the heterogeneity of the weathered fringe of the basement aquifer. Decreasing concentrations of NO3− and δ18O and δ2H values were observed in relation to the distance of the Niger River and increasing thickness of the clay layer on the surface. The wells close to the river in Niamey show a dilution effect during the flood season, and the NO3− concentrations displayed a continuous increasing trend. The δ15N-NO3 and δ18O-NO3 values confirmed that septic tank water is spreading in the region of Niamey and that manure originating from livestock in Kollo is the main source of NO3−. The patterns of δ15N in the soil samples coincide with those of cattle’s manure spread in both areas. The shallow wells show significantly higher values of electric conductivity and NO3− concentrations compared to the deeper wells, which clearly indicates the influence of shallow septic tanks on water quality.

Soil- and Foliar-Applied Silicon and Nitrogen Supply Affect Nutrient Uptake, Allocation, and Stoichiometry in Arabica Coffee Plants

ABSTRACT Silicon (Si) application may affect the plant response to nitrogen (N), possibly by changing the uptake, concentration, and partitioning of nutrients in plant tissues; however, this has not yet been proven in Arabica coffee plants. The effects of Si application methods [no Si, soil-applied soluble Si (168 mg Si L−1), and foliar-applied soluble Si (two application of 2 mg Si plant−1)] and N levels (0 and 80 mg N L−1) on biomass production and partitioning and uptake, partitioning, and stoichiometry of nutrients and Si in young Arabica coffee plants grown under greenhouse conditions were evaluated. Nitrogen fertilization increased the biomass production and uptake of all nutrients; however, reduced the concentrations of K, Ca, Mg, S, Mn, and Si in the leaves, Si in the stems, and K, Mg, and S in the roots of coffee plants as a dilution effect. In the presence of N, soil-applied Si increased the concentrations of Zn in the leaves and Ca and Si in the stems, the uptake of K, S, and Si, and the Si:N ratio. Foliar-applied Si increased the concentrations of N, P, K, and Zn in the leaves and Ca and Si in the stems, as well as the total uptake of K and Si and the Si:N ratio in coffee plants, being more evident in the N fertilization presence. This study unraveled that, especially when it was soil-applied, Si altered the nutrient uptake, allocation, and stoichiometric ratios with N, with a consequent increase in biomass production of young coffee plants fertilized with N.

Grouping Behaviour and Anti-Predator Responses in the Helmeted Guineafowl Numida meleagris

Little is known about landbird group dynamics in response to predation. Here, we describe the interactions between the Helmeted Guineafowl (Numida meleagris) and its predators regarding the survival advantages grouping behaviour may provide. Livestream webcam observations were conducted in Madikwe Game Reserve (South Africa) from August 2020 to August 2021. Emphasis was placed on predator–prey interaction and its effect on group size and structure in a spatial framework. We hypothesise that while grouping is crucial for a number of daily activities in this highly social species, it might turn into a higher predatory pressure. We found, indeed, that the probability of attacks by black-backed jackals (Lupulella mesomelas) significantly increased with guineafowl group size, unlike what happened with raptors. Moreover, when attacked by jackals, the birds responded by standing close to each other. These results suggest, in line with the proposed hypothesis, that a trade-off occurs between the defensive function of grouping in this galliform and the probability of jackal attack that increases as a function of prey group size. Nevertheless, we argue that Helmeted Guineafowl cooperative social groups also play a role as a defensive strategy against predators, with the many-eyes and dilution effects likely compensating for the higher predatory pressure.

The effect of dilution on the energy dissipation in water interstellar ice analogue. Probed by infrared irradiation

Interstellar ices and their energetic processing play an important role in advancing the chemical complexity in space. Interstellar ices covering dust grains are intrinsically mixed, and it is assumed that physicochemical changes induced by energetic processing -- triggered by photons, electrons, and ions -- strongly depend on the content of the ice. Yet, the modelling of these complex mixed systems in experiments and theory is complicated. In this paper, we investigate the effect of infrared irradiation on a series of different molecules mixed with porous amorphous solid water (pASW) to study the release of vibrational energy in the hydrogen-bonding network of water as a function of mixing ratio and ice content. Particularly, we select mixtures of 20:1 H2O :X and 5:1 H2O :X with X= CO2 NH3 or CH4 Infrared radiation was supplied by the intense and tunable free electron laser (FEL) 2 at the HFML-FELIX facility. We monitored the structural changes in the interstellar ice analogue after resonant infrared excitation using Fourier-transform reflection absorption infrared (FT-RAIR) spectroscopy. We observed that on-resonance irradiation at the OH-stretching vibration of pASW results in quantitatively identical changes compared to pure pASW for all investigated mixtures. The structural changes we observed closely resemble the previously reported local reordering. The 5:1 mixtures show weaker changes compared to pure pASW, with a decrease in strength from NH3 to CO2 Since the hydrogen-bonding network of pASW restructures similarly upon FEL irradiation, regardless of the mixing component, treating ice layers in models that simulate energy dissipation in the hydrogen-bonding network as pure H2O ice layers can be a justified approximation. Hence, complex systems might not always be necessary to describe the infrared energetic processing of ices.

Cationic amphiphilic molecules as novel sclerosants for venous malformation treatment: A study on tranexamic acid-derived low-molecular-weight gels

Venous malformation (VM) is a prevalent congenital vascular anomaly characterized by abnormal blood vessel growth, leading to disfigurement and dysfunction. Sclerotherapy, a minimally invasive approach, has become a primary therapeutic modality for VM, but its efficacy is hampered by the rapid dilution and potential adverse effects. In this study, we introduced a series of cationic amphiphilic molecules, fatty alcohol esters (TA6, TA8, and TA9) of tranexamic acid (TA), which self-assembled into low-molecular-weight gels (LMWGs) in water. The TA9, in particular, is released slowly when hydrogel is injected into the vein locally. Then, it damages the venous wall by destroying cell membranes and precipitating proteins, causing inflammation and thrombosis, thickening of the venous wall, effectively inducing irreversible vein fibrosis. Additionally, TA9 can be rapidly degraded into TA in plasma to reduce toxicity caused by diffusion. Overall, this study suggests that the cationic amphiphilic molecule TA9 is a promising sclerosant for VM treatment, offering a novel, effective, and safe therapeutic option with potential for clinical translation.

Effect of gradual pollen presentation on pollination efficiency and reproduction of Vaccinium corymbosum Berkeley in two habitats

IntroductionGradual pollen presentation is a reproductive strategy for plants to improve the efficiency and accuracy of pollen export and acceptance as well as to promote outcrossing. Vaccinium corymbosum Berkeley has a typical mechanism of gradual pollen presentation.MethodsIn this study, we used indoor and outdoor observations to investigate the floral characteristics, pollination characteristics and breeding system of this species in open ground and greenhouse.ResultsThe results showed that the single white, inverted bell-shaped flower of V. corymbosum was able to effectively avoid the negative effects of rainfall, nectar dilution and pollen removal by wind, and improved pollen viability and the duration of stigma receptivity. The setting rate of ‘Northland’ is higher than open ground by artificial pollination in greenhouse, therefore, greenhouses are more suitable for ‘Northland’ reproduction. The gradual pollen presentation prolongs dispersal time, promotes pollinator participation in the pollination process, increases staminate fitness, and provides for nectar feeding by pollinators as well as pollen export. Bombus spp. and A. m. ligustica were effective pollinators in the open ground and greenhouse, and the pollination efficiency of Bombus spp. was higher than that of A. m. ligustica, and greenhouse pollination is more efficient than open ground. The coincidence of the peak period of pollinator visits with the period of highest pollen viability and optimal pollination of stigmas, as well as the high nectar production, could maximize the frequency of pollinator visits and increase the chances of successful pollination as well as the pollination efficiency.DiscussionTherefore, it is important to study the floral characteristics of V. corymbosum Berkeley and the mechanism of gradual pollen presentation in order to improve the pollination efficiency and promote the success of outcrossing, which can provide a theoretical basis for the breeding of V. corymbosum.

Economic Growth Model with Fertility Incentives: A Theoretical Analysis Framework and Policy Simulation for China

This study presents an overlapping generation model to examine the impact of fertility incentive policies on economic growth in China, incorporating endogenous fertility, education, and technological advancement by integrating unified growth theory with an R&D-based growth model. We analyze the impact of fertility incentive policies on economic growth by evaluating maternity insurance and public education. The results show that increasing the actual contribution rate of maternity insurance, maternity benefits, and public education expenditures can boost China’s fertility rate; nevertheless, extending maternity leave would not incentivize an increase in the fertility rate. The impact of fertility incentives on economic growth is ambiguous, depending upon the extent to which increased fertility dilutes aggregate human capital via technical advancement. If the dilution effect is weak, the sign will turn positive, and vice versa. The simulation analysis of the benchmark model indicates that the fertility incentive policy, which encompasses increasing the actual contribution rate of maternity insurance, maternity benefits, and public education expenditure, can foster economic growth in China by enhancing the fertility rate in the long term.

Temporal variation, sources, fluxes, and risk assessment of heavy metals and arsenic in rainwater from Zhanjiang Bay, Northern South China Sea: Impact of typhoons Lion and Kompasu

This study investigates the impact of typhoon-induced rainfall on coastal pollution dynamics in Zhanjiang Bay during the 2021 wet season, focusing on typhoons Lion and Kompasu. Typhoon-induced rainfall (217 mm) contributed 23 % of the total wet season precipitation. Concentrations of Cu, Zn, Cd, and As in rainwater during typhoons were significantly diluted, showing decreases of 48 %, 48 %, 54 %, and 42 %, respectively. In contrast, Pb concentrations remained consistent (29.5 vs. 29.3 μg L−1), indicating that increased local emissions offset the dilution effect. The deposition fluxes of these elements during typhoons accounted for 12–21 % of total wet season deposits. A positive matrix factorization model identified six primary sources, highlighting a rise in coal combustion contributions during typhoons. Overall, while typhoons reduced risks for Cu, Cd, and As, risks for Zn and Pb increased upon deposition on Zhanjiang Bay, illustrating the complex impact of typhoon-induced rainfall on coastal pollution dynamics.

CHEMOUT: CHEMical complexity in star-forming regions of the OUTer Galaxy. IV. ALMA observations of organic species at a galactocentric radius of ~ 23 kpc

Single-dish observations suggest that the abundances of organic species in star-forming regions of the outer Galaxy, which are characterised by sub-solar metallicities, are comparable to those found in the local Galaxy. To understand this counter-intuitive result and avoid a misleading interpretation due to beam dilution effects at these large distances, spatially resolved molecular emission maps are needed to correctly link the measured abundances and local physical properties. We observed several organic molecules with the Atacama Large Millimeter Array towards WB89-671, the source with the largest galactocentric distance (23.4 kpc) of the project CHEMical complexity in star-forming regions of the OUTer Galaxy (CHEMOUT) at a resolution of $ 15000$ au. We compared the observed molecular abundances with chemical model predictions. We detected emission of C$_4$H HCO HCS$^+$, CS, HN13C, and SO. The emission morphology is complex, extended, and different in each tracer. In particular, the most intense emission in and arises from two millimeter-continuum infrared-bright cores. The most intense and SO emission predominantly arises from the part of the filament that lacks continuum sources. The narrow line widths across the filament indicate quiescent gas in spite of the two embedded protostars. The derived molecular column densities are comparable with those in local star-forming regions, and they suggest an anti-correlation between hydrocarbons, ions, HCO, and on the one hand, and and SO on the other. The static chemical models that match the observed column densities best favour low-energy conditions that are expected at large galactocentric radii, but they also favour carbon elemental abundances that exceed those derived by extrapolating the C/H galactocentric gradient at 23 kpc by three times. This would indicate a flatter C/H trend at large galactocentric radii, which is in line with a flat abundance of organics. However, to properly reproduce the chemical composition of each region, models should include dynamical evolution.

Hydrogeochemical evaluation and characterization of water quality in the Phewa Lake, Pokhara, Nepal.

The study was carried out in the Phewa Lake of Pokhara Metropolitan City, Gandaki Province, Nepal, for geochemical assessment and characterization of the lake water quality. A total of 28 water samples were collected in each season from the different zones of the lake in March 2022 (pre-monsoon) and November 2022 (post-monsoon). The lake exhibitedelevated levels of PO43-, NO3-, and NH3, indicating that anthropogenic activities are interfering the lake water. The significant differences in many monitored physicochemical parameters between the pre- and post-monsoon visualize dilution effect in the lake during post-monsoon. Piper diagram illustrates that the majority of water samples in the lake are of Ca-HCO3 type. Additionally, Piper diagram, Gibbs diagram, and Mixing plot illustrate that carbonate weathering is dominant in both seasons. Principal component analysis (PCA) reveals significant correlations among NO3-, SO42-, Na+, and Cl-, demonstrating that pollution in the lake water is attributed to agricultural activities and domestic effluents. In the majority of samples,water quality index (WQI) depicts that the lake water quality is very poor to poor in the pre-monsoon and poor to good in the post-monsoon. Sodium absorption ratio (SAR), % Na (percent sodium), electrical conductivity (EC), cation ratio of soil structural stability (CROSS), and United States Salinity Laboratory (USSL) diagram illustrate that the lake water is suitable for irrigation.

A novel efficient flame-retardant curing agent for epoxy resin based on P-N synergistic effect: Bio-based benzoxazine phosphate ester

Most epoxy resins on the market have low thermal stability and flammable defects. As a potential curing agent for epoxy resin, polybenzoxazine (PBz) can effectively improve the thermal properties of the resin due to its low heat release capacity (HRC) and rigid aromatic ring support, and its raw materials can be derived from renewable resources. Here, we have successfully developed a molecular design strategy to obtain a trifunctional benzoxazine monomer with phosphate ester. Firstly, guaiacol-ethanolamine benzoxazine monomer (GE) was synthesized by Mannich condensation using guaiacol and ethanolamine as raw materials. Then trifunctional benzoxazine phosphate ester (TBP) was synthesized by the nucleophilic reaction of GE with phosphorus oxychloride. Finally, the epoxy resin DGEBA was cured by TBP to obtain a PBz modified epoxy resin (EP-TBP polymer) with Tg of 113.7 °C and char yield of 37.4 %. Due to the introduction of TBP rich in phosphorus and nitrogen, it releases phosphorus radicals and nitrogen-containing inert gases during combustion, which leads to quenching effect and dilution effect. In addition, TBP can also promote the dehydration and dehydrogenation of the polymer and accelerate the formation of the aromatic hybrid char layer. Therefore, the THR of TBP modified epoxy resin is 49.3 % lower than that of epoxy resin without TBP, and the char yield is 47 times higher. And when the phosphorus content is 1.76 %, the flame-retardant grade can reach V-0. In addition, the introduction of TBP also enhanced the mechanical properties, adhesion properties and hydrophobicity properties of the polymer. It is worth mentioning that under alkaline conditions, the phosphate ester in the structure of EP-TBP polymer will undergo ammonolysis reaction with ethanolamine, and the resulting oligomers will be dissolved in it, thereby achieving rapid degradation of EP-TBP polymer. This work is to develop a high-performance multifunctional epoxy resin flame retardant curing agent based on renewable raw materials, and provide important insights for the subsequent development of halogen-free bio-based PBz flame retardant materials.

Unveiling the Effect of Dilution on the Optical Response of Folic Acid Derived Carbon Dots: Role of Surface Interactions and Inner Filter Effect

Unveiling the Effect of Dilution on the Optical Response of Folic Acid Derived Carbon Dots: Role of Surface Interactions and Inner Filter Effect

Reclamation of co-pyrolyzed dredging sediment as soil cadmium and arsenic immobilization material: Immobilization efficiency, application safety, and underlying mechanisms

The safe management of toxic metal-polluted dredging sediment (DS) is imperative owing to its potential secondary hazards. Herein, the co-pyrolysis product (DS@BC) of polluted DS was creatively applied to immobilize soil Cd and As to achieve DS resource utilization, and the efficiency, safety, and mechanism were investigated. The results revealed that the DS@BC was more effective at reducing soil Cd bioavailability than the DS was (58.9–73.2% vs. 21.8–27.4%), except for the dilution effect, whereas the opposite phenomenon occurred for soil As (25.5–35.7% vs. 35.7–42.8%). The DS@BC immobilization efficiency was dose-dependent for both Cd and As. Soil labile Cd and As were transformed to more stable fractions after DS@BC immobilization. DS@BC immobilization inhibited the transfer of soil Cd and As to Brassica chinensis L. and did not cause excessive accumulation of other toxic metals in the plants. The appropriate addition of the DS@BC (8%) sufficiently alleviated the oxidative stress response of the plants and enhanced their growth. These findings indicate that the DS@BC was safe and effective for soil Cd and As immobilization. DS@BC immobilization decreased the diversity and richness of the rhizosphere soil bacterial community because of the dilution effect. The DS@BC immobilized soil Cd and As via direct adsorption, and indirect increasing soil pH, and regulating the abundance of specific beneficial bacteria (e.g., Bacillus). Therefore, the use of co-pyrolyzed DS as a soil Cd and As immobilization material is a promising resource utilization method for DS. Notably, to verify the long-term effects and safety of DS@BC immobilization, field trials should be conducted to explore the effectiveness and risk of harmful metal release from DS@BC immobilization under real-world conditions.

Study of Exhaust Gas Composition and Dilution Effects on Diesel Spray Ignition Characteristics

ABSTRACT Exhaust gas retained in a cylinder is unavoidable, affecting diesel spray ignition. However, its effects on diesel spray ignition characteristics are not completely clear so far, due to the coupled and complicated function of exhaust gas compositions and dilution effects. To reveal the effect mechanism, three-dimensional simulations and chemical kinetics calculations were performed. The results illustrate that with the rise of exhaust gas rate, the initial position of the flame moves downward due to the longer ignition delay. The introduction of exhaust gas compositions decreases both the low-temperature and high-temperature ignition delay while dilution on oxygen mass fraction primarily affects and prolongs the high-temperature ignition delay. Nitric oxide (NO) significantly decreases the ignition delay compared to other exhaust gas compositions, with the high-temperature ignition delay experiencing a substantial decrease of 33.33% under 500 ppm NO addition at the ambient temperature of 820K. With the NO addition in the fresh intake air, conversion reactions occur between NO and nitrogen dioxide, and the reactions of NO with hydroperoxyl (HO2) and nitrogen dioxide with hydrogen radical lead to the generation of hydroxyl radical throughout the low- and high-temperature ignition stages, which enhances system reactivity and contributes to a decrease of ignition delay. The decrease in the oxygen mass fraction significantly reduces the rate of production of HO2 and hydrogen peroxide, which results in a decrease in the rate of production of hydrogen peroxide decomposition and HO2 deoxidation into hydroxyl radicals, prolonging the high-temperature ignition. The revealed mechanism may be applicable to the diagnosis of exhaust gas residual fault phenomenon.

Exploring Deep Eutectic Solvents as Pharmaceutical Excipients: Enhancing the Solubility of Ibuprofen and Mefenamic Acid.

Objectives: The study explores the potential of various deep eutectic solvents (DESs) to serve as drug delivery systems and pharmaceutical excipients. The research focuses on two primary objectives: evaluating the ability of the selected DES systems to enhance the solubility of two poorly water-soluble model drugs (IBU and MFA), and evaluating their physicochemical properties, including density, viscosity, flow behavior, surface tension, thermal stability, and water dilution effects, to determine their suitability for pharmaceutical applications. Methods: A range of DES systems containing pharmaceutically acceptable constituents was explored, encompassing organic acid-based, sugar- and sugar alcohol-based, and hydrophobic systems, as well as menthol (MNT)-based DES systems with common pharmaceutical excipients. MNT-based DESs exhibited the most significant solubility enhancements. Results: IBU solubility reached 379.69 mg/g in MNT: PEG 400 (1:1) and 356.3 mg/g in MNT:oleic acid (1:1), while MFA solubility peaked at 17.07 mg/g in MNT:Miglyol 812®N (1:1). In contrast, solubility in hydrophilic DES systems was significantly lower, with choline chloride: glycerol (1:2) and arginine: glycolic acid (1:8) showing the best results. While demonstrating lower solubility compared to the MNT-based systems, sugar-based DESs exhibited increased tunability via water and glycerol addition both in terms of solubility and physicochemical properties, such as viscosity and surface tension. Conclusions: Our study introduces novel DES systems, expanding the repertoire of pharmaceutically acceptable DES formulations and opening new avenues for the rational design of tailored solvent systems to overcome solubility challenges and enhance drug delivery.