Effect of Kerosene Dual-Jet Spacing on the Mixing and Combustion Characteristics of a Scramjet Combustor.

As the core of a hypersonic propulsion system, the effective mixing efficiency of fuel and air in a supersonic combustor is crucial for its performance. This study focuses on a cold supersonic flow and employs computational fluid dynamics (CFD) techniques combined with Euler-Lagrange method's discrete-phase model (DPM) for multiphase flows, K-H and R-T (Kelvin-Helmholtz and Rayleigh-Taylor) mixing and atomization models, turbulence models, and surface evaporation models to investigate the injection, atomization, and mixing characteristics of kerosene in supersonic airflow. In order to enhance the mixing efficiency between kerosene and air while reducing flow losses, this study examines a staggered dual-jet injection scheme, with the dual jets arranged at the center of the cavity and having a dual-jet spacing of 10 and 20 mm, respectively. Starting from the interaction mechanism between jets, the impact of different staggered dual-jet spacings on the kerosene jet penetration height, span expansion area, angle of the shock wave, and Sauter mean diameter distribution was analyzed. The results show that a short dual-jet spacing (10 mm) leads to greater penetration height, wider span expansion, and a larger angle of the shock wave. When the dual-jet spacing is shorter, the interaction between the fuel jet and the cavity shear layer is stronger, resulting in an improved fuel mixing efficiency. The achievements of this study are consistent with previous experimental measurements and the literature, demonstrating a strong theoretical foundation for optimizing the design of hypersonic engines by deepening the understanding of the fundamental atomization mechanisms of kerosene jets in cold-state supersonic flows. Moreover, these results hold practical significance in improving the efficiency of kerosene combustion and enhancing the performance of flame stabilization devices.

Evaluation of Influences of Changed Lower Cover Geometry on Kerosene-Air Interaction in a Scramjet Combustor.

The fuel in a scramjet combustor must be injected into a high-speed crossflow and mixed with supersonic air in a very short period of time in order for the scramjet jet to operate reliably. More generally, the supersonic air is produced by the lower cover, similar to a Laval type nozzle, of the scramjet combustor. However, significant variation in lower cover geometry is prone to produce unstable vortexes. The unstable vortexes are accompanied by nonuniform stress and strain and are detrimental to the lower cover, even to the combustor. Inspired by mechanical design, this study proposes to change lower cover geometry by decreasing its sizes and then evaluates effects of these changes on kerosene fuel-air interaction in the combustor. The evaluation is based on three-dimensional computational fluid dynamics with couple level set and volume of fluids, which characterizes the penetration height, span expansion area, shock wave angle, and Sauter mean diameter of kerosene jets for three different injection diameters (0.5, 1.0, and 1.5 mm). The simulated air-kerosene interactions reasonably agree with the past numerical findings at identical working conditions. This result demonstrates the effectiveness of the changed lower cover geometry for the scramjet combustor.

Mapping ApoE/Aß binding regions to guide inhibitor discovery.

Blocking the interaction between the E4 isoform of apolipoprotein E (ApoE) and amyloid beta-peptide (Aß) may be an avenue for pharmacological intervention in Alzheimer's disease (AD). The main regions of interaction of the two proteins are, respectively, ApoE244-272 and Aß12-28. These protein segments are too large to facilitate the design of small molecule inhibitors. We mapped the primary components of ApoE/Aß interaction to smaller peptide segments. Within the three motifs that are primarily responsible for ApoE/Aß interaction, we identified four peptides that substantially block ApoE/Aß interaction and further improved their inhibitory activity by rational hydrophobic amino acid substitution. Moreover, the mapping results provide the clue that the Aß residues which interact with ApoE appear to be in the same region where Aß self-interacts. According to this information, we found that Congo Red and X-34 could strongly inhibit ApoE/Aß interaction. Our findings extend our understanding of ApoE/Aß interaction and may guide the discovery of inhibitors that treat AD by antagonizing ApoE/Aß interaction.

Dependence on the properties of organic solvent: study on acyl migration kinetics of partial glycerides.

During Rhizopus oryzae-mediated methanolysis of triglycerides for biodiesel production, the amount of 1,2-DG and 2-MG as well as the ratio of 1,2-DG/1,3-DG and 2-MG/1-MG differed significantly in different reaction medium, which indicated that solvent might be a crucial factor that would influence the acyl migration rate, leading to varied biodiesel yield. In this paper, the influence of solvent and their properties on acyl migration kinetics of both 1,2-diglyceride and 2-monoglyceride were investigated systematically. It was found that decreasing solvent polarity would give increasing acyl migration rate constants in general. Solvent polarity influenced the acyl migration rate through the influence of the charge dispersion of the transition state. High polarity of the solvent was unfavorable to the transition state charge dispersion, which would increase its energy state, and thus decreased the acyl migration rate and then led to relatively lower methyl ester yield.

Prevention and promotion effects of apolipoprotein E4 on amylin aggregation.

The misfolding of islet amyloid polypeptide (IAPP, amylin) results in the formation of islet amyloid, which is one of the most common pathological features of type 2 diabetes (T2D). Amylin, a 37-amino-acid peptide co-secreted with insulin and apolipoprotein E (ApoE) from the beta-cells of pancreatic islets, is thought to be responsible for the reduced mass of insulin-producing beta-cells. However, neither the relationship between amylin and ApoE nor the biological consequence of amylin misfolding is known. Here we have characterized the interaction between ApoE4 and amylin in vitro. We found that ApoE4 can strongly bind to amylin, and insulin can hardly inhibit amylin-ApoE binding. We further found that amylin fibrillization can be prevented by low concentration of ApoE4 and promoted by high concentration of ApoE4. Taken together, we propose that under physiological conditions ApoE4 efficiently binds and sequesters amylin, preventing its aggregation, and in T2D the enhanced ApoE4-amylin binding leads to the critical accumulation of amylin, facilitating islet amyloid formation.

Aquaculture solids management using a combination of sand/gravel or unwoven fabric bed with Lolium perenne Lam as a plant biofilter / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>This work is an evaluation of the efficiency of a sand-gravel or unwoven fabric bed system and Lolium perenne Lam as plant biofilter in the reduction of solids and nutrients removal from aquaculture discharge water.</p><p><b>METHODS</b>The first step consisted of the collection of wastewater in the tank and the distribution at three different hydraulic loading regimes (0.5, 1, 1.5 L/hour) to the different experimental systems. The second step was to evaluate the performance of the different systems. The first system consisted of a bucket filled with a substrate of sand/gravel (20 cm in depth), on the bottom of which was a 80 mesh/inch2 of nylon (S1); the second was similar, but was planted with Lolium perenne lam (S2); the third was planted with a grass plate consisting of 7 layers of unwoven fabric planted with L perenne (S3).</p><p><b>RESULTS</b>The second system showed the best performance in reducing solids as well as in nutrients (TN, TP, and COD) reduction. The removal rates for TS, TN, and TP were negatively correlated with the loading regimes, with 0.5 L/hour being the most efficient and thus taken as the reference.</p><p><b>CONCLUSIONS</b>Solids management using a sand/gravel substrate as bed culture and Lolium perenne L. as plant biofilter has proved to be an efficient technique for solids reduction with low operating cost. This grass plays an important role in wastewater eco-treatment by absorbing dissolved pollutants (TAN) as nutrients for its growth.</p>