Liquid Injection Research Articles

Physical inactivity following volumetric muscle loss results in a divergence between whole-body and cellular metabolic dysfunction

Volumetric muscle loss (VML) is the frank loss of muscle due to injury or surgery and is characterized by whole-body and cellular metabolic dysfunction. Following VML, prolonged bedrest and life-long disability may worsen metabolic dysfunction. This work aimed to elucidate the impact of VML and physical inactivity on the whole-body, cellular, and metabolomic environment of the remaining uninjured muscle. Adult male C57BI/6J mice (n=40) underwent unilateral VML to the posterior hindlimb compartment or served as age-matched injury naïve controls, then were randomized to standard or restricted activity cages for 8-wks. Physical activity, whole-body metabolism, and glucose tolerance were evaluated at 6- and 7-wks post-VML, respectively. Small molecule metabolites and lipids were measured using liquid chromatography-couple and flow injection tandem mass spectrometry. Differences were evaluated by two-way ANOVA with Tukey’s HSD post hoc. Inactivity following VML resulted in ~7% decrease in 24-hr metabolic rate compared to VML alone (p=0.032). Regardless of injury, 24-hr RER was ~5% greater following inactivity (p=0.001). Over 24 hrs, carbohydrate oxidation was ~23% greater with injury and inactivity (p=0.001); lipid oxidation was largely unchanged (p≥0.068). Change in RER (ΔRER) was ~93% greater in VML-injured mice (p=0.030). Physical activity can influence whole-body metabolism, and inactivity post-VML results in greater whole-body carbohydrate usage. Regardless of activity, blood glucose levels were lower following injury (p<0.001). Adiponectin was greater in VML-injured muscles (p<0.001), which may explain enhanced whole-body glucose tolerance post-VML. Protein expression of localized metabolic signals revealed muscle GLUT4, fatty acid binding protein 4, acetyl-CoA carboxylase (ACC), phosphorylated ACC (pACC) and liver fatty acid synthase (FAS) were unaffected by injury and inactivity (p≥0.117). Muscles of inactive, VML-injured mice exhibited a greater pACC:ACC ratio (p=0.046), suggesting decreased fatty acid synthesis. No effect of injury or inactivity was observed in circulating leptin (p≥0.188). Beta-hydroxyacyl CoA dehydrogenase activity was decreased following injury, suggesting a diminished capacity to oxidize fatty acids (p=0.033). Inactivity alone did not alter the metabolome. Injury resulted in 54 significantly expressed metabolites and/or ratios. The combination of injury and inactivity produced a similar response as VML alone, with 91% of metabolites and/or ratios commonly expressed between groups. Similar metabolite expressions following VML with and without inactivity indicate VML injury alone is regulating an altered metabolome. Collectively, although there was no substantial impact of inactivity on whole-body metabolic dysfunction above VML alone, metabolic changes in VML-injured muscles suggests functional alterations in fatty acid metabolism with inactivity. If the ability to oxidize fatty acids is exhausted following VML, resulting accumulation of triglycerides may contribute to metabolic disease often observed with physical inactivity. Continued work to elucidate mechanisms and functional aspects of fatty acid oxidation following VML is needed. W81XWH-20-1-0885 and R01-AR078903 to JAC & SMG. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Evaluation of tubal patency based on peak injection pressure in four-dimensional hysterosalpingo-contrast sonography among infertile females: a preliminary study.

Although the application of four-dimensional hysterosalpingo-contrast sonography (4D-HyCoSy) has relatively good diagnostic accuracy for assessing the patency of the fallopian tubes, the evaluation process mainly relies on morphological findings of the fallopian tubes and pelvic cavity. The purpose of this study was to explore the relationship of peak injection pressure during 4D-HyCoSy and tubal patency to provide a quantitative indicator for the evaluation of fallopian tube patency. This study included infertile patients who underwent 4D-HyCoSy and laparoscopic chromopertubation (LC) between 2020 and 2022, with LC serving as the reference test for assessing tubal patency. For the HyCoSy procedure, the ultrasound contrast agent was injected automatically using a liquid injection machine, and real-time pressure values were recorded. Patients were classified based on tubal patency status in LC as bilaterally patent, unilaterally patent, or bilaterally nonpatent. The average peak injection pressure and contrast agent volume of different groups were compared. Receiver operating characteristic (ROC) curve analysis was employed to determine the cutoff value. A total of 268 infertile patients were enrolled in the study. With LC as the standard examination, the sensitivity and specificity of 4D-HyCoSy in diagnosing nonpatent fallopian tubes were 91.1% and 95.1%, respectively. In general, peak injection pressure was observed to gradually increase as tubal patency decreased (P<0.001), with average peak injection pressures of 233.5±66.3, 338.8±99.8, and 469.6±63.1 mmHg in the bilaterally patent, unilaterally patent, and bilaterally nonpatent groups, respectively. The volume of contrast agent used in patients in the bilaterally nonpatent group was significantly lower than that in the other two groups (P<0.01), with average volumes of 22.7±6.3, 24.3±9.3, and 18.9±9.2 mL, respectively. When one fallopian tube was patent, the area under the curve (AUC) for distinguishing obstruction from patency of the other fallopian tube was 0.827, with a sensitivity of 79.8% and a specificity of 74.3% (cutoff value: 254.3 mmHg). Similarly, when one fallopian tube was nonpatent, the AUC was 0.866, with a sensitivity of 90.6% and a specificity of 78.3% (cutoff value: 401.3 mmHg). Peak injection pressure during 4D-HyCoSy demonstrates promising diagnostic performance in evaluating fallopian tube patency in infertile patients.

Composite wick heat pipe fabrication and performance study

A composite wick heat pipe is designed and prepared: a copper mesh is fixed on the copper pipe, and copper powder is filled in the gap between the mesh and the mandrel through the mandrel. A test device is assembled to test the maximum thermal conductive power and temperature stabilization time of the heat pipe. The results show that: the composite wick structure and the copper powder structure compared with the ultimate heat transfer performance increased by 20%, when the heat capacity is increased, the overall temperature difference will increase accordingly, and the optimal liquid injection rate of 100%, the ultimate power of up to 100 W, when filling with powder, it has the best thermal conductivity, the ultimate heat transfer power in the state of gravity is three times higher than that of the state of resistance to gravity, and it is 28.6% higher than that in the state of horizontality. The composite wick structure starts 17.6% faster than the copper powder structure.

Stochastic models in the under-resolved simulations of spray formation during high-speed liquid injection

In the under-resolved simulation of the high-speed liquid injection into stagnant air, the attention in subgrid-scale models is focused on events of intense gradients of the velocity in turbulent flow, i.e., on effects of intermittency. Three typical flows are considered—the in-nozzle flow, primary atomization zone, and secondary atomization of spray droplets. In the simulation of the first two flows, the filtered Navier–Stokes equations are forced by stochastic processes with properties which incorporate the statistical physics of fluid acceleration at the high Reynolds number—in this way we update the under-resolved acceleration. In the case of in-nozzle flow, the proposed stochastic subgrid acceleration model is combined with wall-damping function, and the ability in prediction of the velocity statistics is demonstrated. In the simulation of primary atomization, the approach with stochastic subgrid acceleration is combined with the volume of fluid method. This leads to intensification of the interface dynamics, resulting in additional corrugation, with more intense shearing and stretching of liquid structures are observed. Thereby, the experimental profiles of the time-averaged liquid volume fraction distribution for four different axial locations are rather well predicted. The secondary atomization of droplets is simulated by a new stochastic model for the breakup rate along the droplet path. To this end, the breakup rate is expressed as a function of turbulent viscous dissipation which evolves along the droplet path according to the proposed stochastic process. Preliminary assessment performed against the recent experiments shows the correct predictability of this model and its low sensibility to the grid density.

Parametric analysis of the Charge-Hold-Vent method for cryogenic propellant tank chilldown

In the absence of external heat exchangers, the on-orbit transfer of cryogenic propellants requires the receiver tank to first be quenched to a sufficiently low energy state to allow for a continuous no-vent fill to avoid unnecessary venting of liquid. One proposed method for tank chilldown that minimizes the potential for venting liquid is the charge hold vent (CHV) method. CHV follows a cyclic process that gradually removes thermal energy from the receiver tank by injecting liquid with the vent valve closed and allowing the fluid and wall to reach near-thermal equilibrium before venting the superheated vapor. However, the CHV method must be optimized to minimize complexity, mass, and time. This paper presents a modular CHV analytical model used to quantify the number of cycles and propellant mass consumed based on first principles. The model is used to examine the effect of eight parameters: receiver tank material, volume, mass, maximum expected operating pressure, and initial pressure, liquid injection pressure and temperature, and the target temperature. The model is validated against the only two available CHV datasets. Based on results, the tank mass-to-volume ratio is the most important factor in determining the number of CHV cycles and thus degree of difficulty in tank chilldown. The model can easily be used for early-stage design, sizing, and analysis of cryogenic propellant transfer systems.

High-pressure liquid refrigerant injection for reciprocating compressors

Isentropic (adiabatic) compression of superheated vapor in vapor compression refrigeration cycles usually results in some discharge superheat, i.e. the discharge temperature exceeding the condensing temperature. Large discharge superheat reduces both operating range and compression efficiency. Sub-isentropic compression with heat rejection to the heat sink is therefore superior to adiabatic compression, as it results in lower discharge superheat and improved efficiency. However, significant temperature reduction by heat transfer through the working chamber walls is difficult to facilitate in common refrigeration compressors, particularly reciprocating compressors. Refrigerant and oil injection is a well-established method for reducing temperatures and increasing efficiency in screw and scroll compressors, as well as multi-stage systems. In comparison, effective methods for temperature reduction in single-stage reciprocating compressors are fairly limited. Therefore, a concept for high-pressure liquid injection is proposed. By means of a pump and injection valve, high-pressure liquid refrigerant is injected into the working chamber and atomized. The compressed gas is cooled through the evaporation of the injected liquid. The injection valve allows for control over the injection timing and quantity, enabling adjustment of the temperature profile, which is a major distinction from existing refrigerant injection methods. The coupled compression-injection process is evaluated for various refrigerants using an energetic chamber model. The injection is found to be particularly suitable for refrigerants with a large evaporation heat and a shallow dew line slope. For the example of ammonia, a theoretical reduction in compression work of 8.9% at an evaporation temperature of −10 °C and a condensing temperature of 45 °C is found.

A versatile economic strategy by HPLC–CAD for quantification of structurally diverse markers in quality control of Shengmai Formula from raw materials to preparations

BackgroundShengmai Formula (SMF), a classic formula in treating Qi-Yin deficiency, is composed of Ginseng Radix et Rhizoma Rubra (GRR), Ophiopogon Radix (OR), and Schisandra chinensis Fructus (SC), and has been developed into various dosage forms including Shengmai Yin Oral Liquid (SMY), Shengmai Capsules (SMC), and Shengmai Injection (SMI). The pharmacological effects of compound Chinese medicine are attributed to the integration of multiple components. Yet the quality criteria of SMF are limited to monitoring schisandrol A or ginsenosides Rg1 and Re, but none for OR. Since the complexity of raw materials and preparations, establishing a economical and unified method for SMF is challenging. It is urgent to simultaneously quantify multiple components with different structures using a universal method for quality control of SMF. Charged aerosol detector (CAD) overcame the above shortcomings owing to its characteristics of high responsiveness, nondiscrimination, and low cost. PurposeWe aimed to establish a versatile analysis strategy using HPLC–CAD for simultaneously quantifying the structurally diverse markers in quality control of SMF from raw materials to preparations. MethodBy optimizing the column, mobile phase, column temperature, flow rate, and CAD parameters, a HPLC-CAD method that integrated multi-component characterization, authenticity identification, transfer information of raw materials and quantitative determination of Shengmai preparations was established. ResultsIn total 50 components from SMF were characterized (28 in GRR, 13 in SC, and 9 in OR). The differences in raw materials between species of SC and Schisandrae sphenantherae Fructus (SS), processing methods of Ginseng Radix (GR) and GRR, and locations of OR from Sichuan (ORS) and Zhejiang (ORZ) were compared. Fourteen components in 19 batches of SMY, SMC and SMI from different manufacturers were quantified, including 11 ginsenosides and 3 lignans. The multivariate statistical analysis results further suggested that Rb1, Rg1 and Ro were the main differences among Shengmai preparations. ConclusionThe established versatile analysis strategy based on HPLC–CAD was proven sensitive, simple, convenient, overcoming the discriminatory effect of UV detector, revealing the composition and transfer information of SMF and applicable for authentication of the ingredient herbs and improving the quality of Shengmai preparations.

Experimental Investigation of Superheated Liquid Injection in Quiescent and Supersonic Crossflow

This research delves into liquid fuel injection in scramjet combustors, with a focus on the effects of injector length-to-diameter (L/D) ratios and temperatures, spanning from ambient to superheated states. Efficient atomization within the short residence times of liquid-fueled supersonic combustors is crucial for maximizing combustion efficiency. Initial investigations in a quiescent environment aimed to isolate the impact of injector geometry and temperature, utilizing quantitative analysis and diffused backlit illumination to demonstrate that heating fuel beyond its boiling point significantly enhances atomization and dispersion. A notable finding is that higher L/D ratios led to a quicker initiation of flash boiling. Subsequent analyses under supersonic crossflow, using two-dimensional planar laser-induced fluorescence, support these observations. The study further employs spray structure and spatiotemporal characteristic analyses, coefficient of variation, and proper orthogonal decomposition, revealing enhanced flashing atomization at higher L/D ratios. This underscores the critical role of injector design and temperature in optimizing fuel atomization in scramjet engines, highlighting the nuanced interplay between physical injector characteristics and thermal properties in achieving efficient combustion.

Rare-earth doped yttrium silicate (Y2SiO5) thin films grown by chemical vapour deposition for quantum technologies

Yttrium orthosilicate (Y2SiO5 - YSO) is one of the most promising crystals to host rare-earth (RE) ions for quantum technologies applications. In this matrix, they indeed exhibit narrow optical and spin linewidths that can be exploited to develop quantum memories or quantum information processing capabilities. In this paper, we propose a new method to grow RE doped silicate thin films on silicon wafers based on direct liquid injection chemical vapour deposition (DLI-CVD). We optimize the deposition and annealing conditions to achieve formation of the high temperature X2-YSO phase. The phase purity and crystalline quality of the films are assessed by evaluating the optical properties of Eu3+ ions embedded in this oxide matrix. In view of the results, we discuss the possible phase formation mechanisms, and the potential of this new wafer-compatible form of YSO for quantum technologies applications.

Effects of liquid water injection on flame surface topology and propagation characteristics in spray flames: A direct numerical simulation analysis

The effects of water injection on flame surface topology and local flame propagation characteristics have been analyzed for statistically planar turbulent n-heptane spray flames with an overall (i.e., liquid + gaseous) equivalence ratio of unity using carrier-phase direct numerical simulations. Most fuel droplets have been found to evaporate as they approach the flame even though some droplets can survive until the burnt gas side is reached, whereas water droplets do not significantly evaporate ahead of the flame and the evaporation of water droplets starts to take place in the reaction zone and is completed within the burnt gas. However, the gaseous-phase combustion occurs predominantly in fuel–lean mode although the overall equivalence ratio remains equal to unity. The water injection has been found to suppress the fuel droplet-induced flame wrinkling of the progress variable isosurface under the laminar condition, and this effect is particularly strong for small water droplets. However, turbulence-induced flame wrinkling masks these effects, and thus, water injection does not have any significant impact on flame wrinkling for the turbulent cases considered here. The higher rate of evaporation and the associated high latent heat extraction for smaller water droplets induce stronger cooling effects, which weakens the effects of chemical reaction. This is reflected in the decrease in the mean values of density-weighted displacement speed with decreasing water droplet diameter. The weakening of flame wrinkling as a result of injection of small water droplets is explained through the curvature dependence of the density-weighted displacement speed. The combined influence of cooling induced by the latent heat extraction of water droplets and flame surface flattening leads to a decrease in volume-integrated burning rate with decreasing water droplet diameter in the laminar cases, whereas the cooling effects are primarily responsible for the drop in burning rate with decreasing water droplet diameter in the turbulent cases.

Experimental study on generation and growth of bubbles in external flash-boiling spray regime

High-performance liquid propulsion systems, such as hypersonic scramjets and liquid rockets, utilize regenerative cooling by employing fuel as a coolant to shield components from thermal damage. The flash-boiling spray, resulting from superheated liquid injection and prevalent in regenerative cooling, has received considerable research interest for enhancing atomization and combustion efficiency. In this study, superheated water jets at various temperatures between 30 and 90 ℃ were injected into a vacuum chamber at different pressures above 5 kPa, and their spray patterns were acquired through diffusive backlight imaging. Images were analyzed to determine key parameters, such as bubble nucleation flux, bubble growth rate, and spray angle, in an external flash-boiling spray regime. The estimated nucleation flux agreed well with the predictions the model based on nucleation theory in the region of sufficiently high superheat. The dynamics of bubble growth was investigated and explained using a bubble growth model. The jet-expansion energy was computed by measuring the spray angle and compared with the available energy. By mapping the evolution of flash-boiling spray in relation to relevant nondimensional numbers, the study underscores the necessity of accounting for the pressure inside the injector to adequately model bubble generation inside the injector. Furthermore, this study substantiates the feasibility of visually recognizing and analyzing individual bubbles in the external flash-boiling regime, thereby enabling the generation of experimental data crucial for the validation of bubble nucleation and growth models.

Migration characteristics of constant elements in the process of coal dissolution by liquid CO2

The effect of liquid CO2 on coal dissolution plays a key role in improving coal bed methane (CBM) recovery and CO2 geological storage. In order to study the effect of liquid CO2–H2O reaction on the migration of mineral constant elements in coal, three kinds of coal samples (lignite, bituminous coal, and anthracite) with different degrees of metamorphism were selected as the research objects. The one-factor experiments of dissolution of liquid CO2 and water-bearing coal samples were carried out by simulating the temperature and pressure of the stratum. X-ray fluorescence spectroscopy (XRF) was used to test the changes in the relative content of constant elements in coal samples after liquid CO2 injection under different pressure conditions. Scanning electron microscopy (SEM) was utilized to observe the evolution pattern of the surface features of the coal before and after the dissolution of liquid CO2. A quantitative analysis of coal pore development characteristics was conducted based on low-temperature N2 adsorption/desorption experiments, and isothermal adsorption experiments were carried out before and after etching the coal samples to understand the adsorption characteristics of CH4 and CO2 by coal under different pressure conditions. The research results indicated that the migration ability of constant elements in coal showed a trend of first decreasing and then increasing with the increasing degree of coal metamorphism. Among the three selected coal samples, the migration ability of constant elements was found to be strongest in anthracite, followed by lignite and bituminous coal. Most of the element migration in coal was carried out through chemical reactions (hydrolysis, carbonation, redox), while some elements were primarily transported through physical means (such as the low-temperature impact of liquid CO2). The dissolution process expands the original pore space of coal and generates new pores, greatly increasing the coal's capacity for CO2 adsorption. These findings deepen our understanding of mineral dissolution in coal by liquid CO2 and provide important insights for achieving efficient and long-term coalbed CO2 geological storage and enhanced methane recovery techniques.

Effects of biodiesel injector configuration and its injection timing on performance, combustion and emissions characteristics of liquid ammonia dual direct injection engine

Ammonia is a promising carbon-neutral fuel that can be stored and transported in liquid form, offering a viable alternative to diesel fuel. In addition, it can be used directly in diesel engine in its liquid form in dual fuel mode. Hence, a single-cylinder diesel engine was modified to implement two common rail (CR) injection systems, allowing the direct injection of liquid ammonia with biodiesel. As biodiesel was used for a pilot fuel with lower injected mass, this study aims to investigate the influence of the number of nozzles in the biodiesel injector on the performance, combustion, and emissions characteristics of the liquid ammonia-biodiesel dual direct injection engine. Therefore, the number of holes in the CR injector was closed in various configurations to improve injection parameters. Furthermore, various biodiesel start of injection (SOI) timings were tested, ranging from −24 to −14 CAD, while the SOI of ammonia was kept at −10 CAD with an ammonia mass ratio of 67.2%. The results showed that welding three nozzles from the original six-nozzle injector resulted in a remarkable 29.2% reduction in NH3 and CO emissions. Furthermore, the highest indicated thermal efficiency of 39.7% was obtained for the injector with 3b nozzles. Additionally, late injection of both fuels led to an increase in particulate matter emissions, from 10.5 to 15.2 mg/m3, due to the formation of fuel-rich zones at high temperatures. However, it reduced NOx and CO emissions by 1.4 and 4.4 g/kWh, respectively, compared to the early SOI of biodiesel. Moreover, the lowest N2O emission was measured at 115.0 ppm in the earliest SOI of biodiesel at −24 CAD.

Experimental simulation of water-coal interactions during liquid CO2 injection into coal beds

Injection of liquid CO2 (LCO2) into coal reservoirs is an extremely effective way to enhance coalbed methane recovery and storage. This study aimed to investigate the changes in mineral composition and content during the chemical reaction between coal samples and weakly acidic fluids dissolved in LCO2. Therefore, in this study, simulating the formation temperature (30 °C), three types of coal samples with different metamorphic degrees (lignite, anthracite, and bituminous coal) were selected for CO2–H2O-coal interaction leaching experiments under various pressure conditions (1 MPa, 3 MPa, 5 MPa). X-ray diffraction analysis (XRD) was used to test coal samples' mineral composition and content before and after LCO2 injection under different pressure conditions. Scanning Electron Microscope (SEM) was used to observe the evolution pattern of surface characteristics before and after the dissolution of the coal body by LCO2. The results showed that minerals such as kaolinite, illite, quartz, and potassium feldspar in the three coal samples underwent mineral transformation during the reaction process at different dissolution pressures, and the content changed significantly in the early stage of the reaction. The initial content of kaolinite in the bituminous coal (16.5%) increased to 23.8%, 26.7%, and 25.2% respectively under different leaching pressures of 1 MPa, 3 MPa, and 5 MPa. Carbonate minerals dissolved rapidly in the initial stages of the reaction, the initial content of calcite, a carbonate mineral in the anthracite (9.8%), decreased to 4.2%, 3.8%, and 2.4% respectively under different leaching pressures of 1 MPa, 3 MPa, and 5 MPa. Similarly, the initial content of siderite decreased from 6.8% to 2.8%, 2.3%, and 1.6% respectively. LCO2 pressure had a significant influence on the reaction. These results advance our understanding of LCO2 dissolution of minerals in coal.

Spectral averaging with outlier rejection algorithms to increase identifications in top-down proteomics.

The identification of proteoforms by top-down proteomics requires both high quality fragmentation spectra and the neutral mass of the proteoform from which the fragments derive. Intact proteoform spectra can be highly complex and may include multiple overlapping proteoforms, as well as many isotopic peaks and charge states. The resulting lower signal-to-noise ratios for intact proteins complicates downstream analyses such as deconvolution. Averaging multiple scans is a common way to improve signal-to-noise, but mass spectrometry data contains artifacts unique to it that can degrade the quality of an averaged spectra. To overcome these limitations and increase signal-to-noise, we have implemented outlier rejection algorithms to remove outlier measurements efficiently and robustly in a set of MS1 scans prior to averaging. We have implemented averaging with rejection algorithms in the open-source, freely available, proteomics search engine MetaMorpheus. Herein, we report the application of the averaging with rejection algorithms to direct injection and online liquid chromatography mass spectrometry data. Averaging with rejection algorithms demonstrated a 45% increase in the number of proteoforms detected in Jurkat T cell lysate. We show that the increase is due to improved spectral quality, particularly in regions surrounding isotopic envelopes.

Universal basic income on blockchain: the case of circles UBI

The paper reviews Circles UBI as an illustrative case study of implementing the idea of universal basic income (UBI) on blockchain. Circles was born out of the Gnosis Chain as a more democratic alternative to Bitcoin coupled with the ambitious political project of algorithmically distributing UBI. Backed by the Gnosis Chain, Circles Coop was founded in 2020 to implement this idea in Berlin. Examining the failure of the Berlin pilot helps us draw substantial conclusions with regard to the implementation of UBI on blockchain. UBI alone, on blockchain or not, is not enough to solve the problems its proponents argue against. UBI would be helpful as a tool if plugged into a model of production embedded into a political strategy aiming to fix key problems of current societies such as gaping inequalities and climate change. We give a snapshot here of the model of open cooperativism as a counter-hegemonic political project vis-à-vis neoliberalism. Circles UBI could plug into the model of open cooperativism as a distribution and liquidity injection mechanism to foster the transition towards a commons-based ethical and sustainable post-capitalist economy.

Effect of liquid ammonia HPDI strategies on combustion characteristics and emission formation of ammonia-diesel dual-fuel heavy-duty engines

Reducing carbon emissions from internal combustion engines has become a crucial topic due to the pressure brought about by global warming. Ammonia, a carbon-free fuel, has significant potential for heavy-duty diesel engine applications. However, the laminar flame speed of ammonia fuel is relatively slow, resulting in suboptimal combustion performance. Therefore, the present study focuses on ammonia-diesel dual-fuel heavy-duty engines. A novel liquid ammonia high-pressure direct injection (HPDI) strategy has been developed to address the challenges associated with poor combustion performance and increased unburned ammonia emissions in ammonia-diesel dual-fuel internal combustion engines. Firstly, a three-dimensional numerical simulation method was utilized to establish and verify a model of a heavy-duty internal combustion engine that incorporates HPDI of liquid ammonia. Afterward, numerical studies comparing the engine's combustion and emission characteristics are conducted with varied ammonia energy fractions, liquid ammonia injection timings, and liquid ammonia injection directions. The results indicate that, compared to the pure diesel mode, the novel liquid ammonia HPDI strategy can alter the combustion mode, significantly improving fuel–air mixture efficiency. This leads to more thorough combustion. After replacing 80% of the fuel energy input with ammonia, there is still an increase of 8.9% in indicated mean effective pressure and a 10.6% improvement in indicated thermal efficiency. Moreover, modifying the HPDI strategy reduces greenhouse gas emissions effectively, and due to the thermal de-NOx reaction, there is a notable decrease in NOx emissions. Furthermore, by altering the liquid ammonia injection timing and direction, finer control of fuel combustion and pollutant generation can be achieved, thereby reducing unburned ammonia emissions in conditions of high ammonia energy fractions.

Determining by Raman spectroscopy the average thickness and N-layer-specific surface coverages of MoS2 thin films with domains much smaller than the laser spot size.

Raman spectroscopy is a widely used technique to characterize nanomaterials because of its convenience, non-destructiveness, and sensitivity to materials change. The primary purpose of this work is to determine via Raman spectroscopy the average thickness of MoS2 thin films synthesized by direct liquid injection pulsed-pressure chemical vapor deposition (DLI-PP-CVD). Such samples are constituted of nanoflakes (with a lateral size of typically 50 nm, i.e., well below the laser spot size), with possibly a distribution of thicknesses and twist angles between stacked layers. As an essential preliminary, we first reassess the applicability of different Raman criteria to determine the thicknesses (or layer number, N) of MoS2 flakes from measurements performed on reference samples, namely well-characterized mechanically exfoliated or standard chemical vapor deposition MoS2 large flakes deposited on 90 ± 6 nm SiO2 on Si substrates. Then, we discuss the applicability of the same criteria for significantly different DLI-PP-CVD MoS2 samples with average thicknesses ranging from sub-monolayer up to three layers. Finally, an original procedure based on the measurement of the intensity of the layer breathing modes is proposed to evaluate the surface coverage for each N (i.e., the ratio between the surface covered by exactly N layers and the total surface) in DLI-PP-CVD MoS2 samples.

Fiber‐Format Dielectric Elastomer Actuators by the Meter

AbstractDielectric elastomers in the shape of thin films are heavily investigated, but they do not produce beneficial strains and forces comparable to that of skeletal muscles without entailing extremely complicated fabrication processes, rendering their practical use limited. Here, a silicone elastomer fiber is reported that can be produced by the meter and turned into an actuator by a simple process entailing the injection of an ionic liquid as the inner electrode and dipping in an ionogel to form the outer electrode. The fibers range from 174 to 439 µm in outer diameter with wall thicknesses from 62 to 108 µm and can be produced by the meter with regular diameter and thickness. The mechanical properties of the fibers are unaffected by the electrodes and actuation strains of 10% can be achieved, in both dry and wet environments. The fiber actuator can be bundled to mimic human skeletal muscle bundles or used in folded configurations, rendering it ideal as a building block for macroscopic actuators that can be used for many products such as body‐compliant actuators and wearables.

Numerical simulation and spray model development of liquid ammonia injection under diesel-engine conditions

Ammonia is regarded as a promising alternative fuel in internal combustion engine for its potential to reduce carbon emissions. Injection process of liquid ammonia will affect air-fuel mixture distribution and therefore combustion efficiency and NOx emissions. However, the experimental studies of liquid ammonia injection under engine conditions are limited, and the key impact factors of spray evolution are still unclear. This study aims to evaluate the applicability of numerical models for liquid ammonia spray, and numerically investigate spray characteristics under diesel-engine conditions (ambient temperature > 800K, ambient pressure > 2 MPa). Large eddy simulation coupled with Lagrangian particle tracking method were conducted, and the results show that the non equilibrium - Frössling phase change model coupled with Schiller-Naumann drag model can provide a good prediction of spray penetration. Liquid penetration increases with ambient pressure decreasing; vapor penetration increases with ambient density decreasing, but insensitive to ambient temperature. Temperature - mixture fraction distribution is sensitive to ambient temperature and superheat degree. Besides, a three-stage 0D model of spray tip penetration under diesel-engine conditions is developed firstly, which can reflect the key impact factors of ammonia spray evolution and provide theoretical support to optimize fuel injection strategy of liquid ammonia-fueled engines.