Search

Successful delivery of drugs to the Olfactory region (OR) is the key to treating diseases through the nasal cavity. The purpose of this paper is to investigate the effect of auxiliary airflow on particle deposition in the OR during nasal drug administration. A realistic 3D nasal ensemble model was reconstructed from CT scans of the head of a healthy adult. Computational fluid dynamics (CFD) was used to simulate the effect of auxiliary airflow on the deposition of drug particles in the OR during nasal administration. The discrete phase model (DPM) was adopted to track the deposition trajectories of drug particles. Three auxiliary airflows were selected together with three spray cone angles, four particle sizes, five drug particle delivery velocities and three specific injection positions on the deposition fraction of drug particles in the OR were analyzed. The results indicated that the effect of auxiliary airflow on the deposition fraction of drug particles of different particle sizes in the OR is significant. The delivery efficiency of injection position C is always the greatest. A delivery velocity of 15 m/s is more favorable for nasal administration and the effect of spray cone angle is proportional to the auxiliary airflow. Computational results should be helpful for experimental studies and future nasal optimization. [Display omitted] • The effect of auxiliary airflow on particle deposition is systematically studied. • Drug particles are released at specific locations in the nasal cavity. • The effects of particle parameters are systematically investigated. • Some mechanisms of the effect of auxiliary airflow on deposition are studied. [ABSTRACT FROM AUTHOR]

• Varied textures were feasibly controlled by combined-extrusion techniques. • Semianalytical Sachs model well predicted flow stress in tension/compression. • Asymmetry was improved by balancing slip/twinning contribution relying on texture. • Symmetric high-strength ZK61 achieved by texture dispersion via DUE technique. Three combined-extrusion techniques of second extrusion, die upsetting and extrusion, and cyclic extrusion and compression were used to fabricate three typical {0002} basal textures of fiber texture, dispersed texture and inclined texture, respectively, in the fine-grained ZK61 magnesium alloy. The tension-compression asymmetries were compared and the texture influence on asymmetry mechanical response was well evaluated using a Semianalytical Sachs model that followed Schmid law and highlighted the importance of slip/twining activity in tension-compression asymmetry. It was found that in strong fiber-textured materials, solely refining grains could not obviously improve the tension-compression asymmetry. However, basal texture dispersed/inclined was conducive to activation of basal slip in tension and impeding of twining in compression, leading to gentler strain hardening and low tension-compression asymmetry. The uniaxial symmetry managed to be kept in cyclic loading under low strain amplitude, with the cyclic maximum stresses in accordance with uniaxial yield values. Symmetric high-strength ZK61 magnesium alloys with tensile and compressive yield stresses (1.0 % offset) over 300 MPa were achieved by basal texture dispersion feasibly controlled by die upsetting extrusion technique. [ABSTRACT FROM AUTHOR]

Upsetting-extrusion (UE) process effectively prepared high-strength ZK61 magnesium alloy rods with tension/compression symmetry. The influence of upsetting-extrusion temperature and upsetting ratio on microstructure was studied. Microstructure evolution in the UE process included two stages: {10–12} tensile twinning significantly divided and refined the coarse grains in upsetting stage, forming a <0001>//ED (extrusion direction) texture component; grain refinement suppressed the inverse occurrence of {10–12} tensile twinning during extrusion stage, promoting multi-slip deformation and dynamic recrystallization (DRX) and leading to the diffused {0001}//ED texture. Lowering temperature and increasing upsetting ratio played positive roles in twinning division and DRX refinement. Both of them were beneficial to basal texture weakening which could effectively inhibit the activation of tensile twinning during compression, and promote basal slip contribution during tension, thus improving tension/compression asymmetry. The relationship between microstructure and tension/compression yield strengths was analyzed by texture-dependent Hall-Petch relationship composed of slip and twinning deformation mechanisms. Only slight weakening of the extruded fiber texture was required for tension/compression symmetry for fine-grained structure; but it was the opposite for coarse-grained structure. Correspondingly, only smaller critical upsetting ratio was needed at lower upsetting temperature. • Tension/compression symmetry achieved by upsetting-extrusion process. • Twinning division in upsetting aided grain refinement and basal texture weakening. • Dominant deformation mechanisms investigated from strain hardening and Schmidt factor. • Texture-dependent Hall-Petch relationship including slip and twinning was established. [ABSTRACT FROM AUTHOR]

To address the excessive formation of brittle compounds when brazing TiAl alloys, a TiZrHfCoNiCu high-entropy brazed filler was developed to realize the brazing of TiAl/Ti 2 AlNb couples. The TiAl/Ti 2 AlNb brazed joints can be divided into 4 zones, i.e., 2 diffusion zones at the TiAl/braze filler, Ti 2 AlNb/braze filler interfaces and 2 zones divided inside the brazed seam. α 2 + γ-TiAl were the main reaction products formed at the TiAl/braze filler interface and α 2 + Ti 0.5 Al 0.12 Nb 0.38 were the main reaction products at the Ti 2 AlNb/braze filler interface. Effects of brazing temperatures on the interfacial microstructure and mechanical properties of the TiAl/Ti 2 AlNb brazed joints were investigated. When brazing at 1100°C/15 min, the highest shear strength can reach 157 MPa (room temperature), and 123 MPa (650°C) respectively. The relationship between the microstructure and the corresponding mechanical response were discussed in detail. This research can offer new insights on developing desirable brazing filler when joining TiAl and TiAl based alloys. • A TiZrHfCoNiCu high-entropy alloy braze filler was developed to realize the brazing of TiAl/Ti2AlNb couples. • Ti 0.5 Al 0.12 Nb 0.38 and α 2 + γ-TiAl formed at the braze filler/base metal interfaces were the key to realize the joining. • The α 2 + γ-TiAl at the TiAl/braze filler interface was preferential to crack for the strongest brazed joints. • Highest shear strength of 157 MPa (room temperature) and 123 MPa (650°C) were achieved at 1100°C/15 min. [ABSTRACT FROM AUTHOR]