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The as-cast Mg–2Y-0.5Zn-0.5Ni-0.5Co alloy (MYZNC, at%) underwent composite hot working, extrusion and rolling to further improve the mechanical properties, and the corresponding microstructure and mechanical properties were also investigated. The extruded and rolled MYZNC alloy (MYZNC-R) consisted of α-Mg, a long period stacking order (LPSO) phase comprising lamellar and fine block 18R LPSO phase as well as a thin strip 14H LPSO phase, along small amounts of Mg2Y, MgY(Co,Zn,Ni)4 and Mg3(Co,Zn,Ni,Y) particle phases. After composite processing, the dispersion and amounts of LPSO phase in the alloy was significantly enhanced, accompanied by a substantial introduction of low angle grain boundaries (LAGBs) during rolling process. The MYZNC-R alloy exhibited the high mechanical properties, with an ultimate tensile strength (σb) of 350 MPa, a yield strength (σ0.2) of 305 MPa and an elongation to failure (εf) of 10.6 %. In comparison to the extruded MYZNC alloy, both σb and σ0.2 demonstrated significant improvements by 25 % and 35.6 %, respectively. The elongation to failure only decreased by mere 1 %, indicating that the alloy had a good strength-plasticity. The high tensile strengths of MYZNC-R alloy were mainly attributed to grain refinement, LPSO phase strengthening and texture strengthening. The good ductility of MYZNC-R alloy was associated with the coordinated deformed LPSO phase and the formation of a high-volume fraction (∼76.5 %) of LAGBs.

Summary: The pilosebaceous unit (PSU) is composed of multiple compartments and the self-renewal of PSU depends on distinct hair follicle stem cell (HFSC) populations. However, the differential roles of the HFSCs in sebaceous gland (SG) renewal have not been completely understood. Here, we performed multiple lineage tracing analysis to unveil the contribution of different HFSC populations to PSU regeneration during the hair cycle and wound healing. Our results indicated that the upper bulge stem cells contributed extensively to the SG replenishment during hair cycling, while HFSCs in the lower bugle did not. During skin wound healing, all HFSC populations participated in the SG replenishment. Moreover, β-catenin activation promoted the contribution of HFSCs to SG replenishment, whereas β-catenin deletion substantially repressed the event. Thus, our findings indicated that HFSCs contributed to SG replenishment in a β-catenin-dependent manner.

A microstructure-based numerical simulation is performed to understand the mechanical properties and fracture of a Ti-Al3Ti core-shell structured particulate reinforced A356 composite ((Ti-Al3Ti)cs/A356). A series of two-dimensional (2D) representative volume element (RVE) models are generated automatically by embedding Ti-Al3Ti core-shell structured particulates in an A356 matrix. Microstructure-based 2D RVE of monolithic Al3Ti particulate reinforced A356 composite (Al3Tip/A356) is also simulated for comparison. The ductile fracture of both Ti core and A356 matrix as well as the brittle fracture of the Al3Ti shell are considered. The simulation confirms that the high elongation of the (Ti-Al3Ti)cs/A356 composite is attributed to the uniform distribution of the overall ductile globular reinforcing particulates, which prevent a premature failure effectively by reducing local stress concentration both on and inside the core-shell structured particulates. The surrounding ductile phases of the Al3Ti shell blunt the crack tips effectively and, therefore, restricting the propagation of the cracks in a nominal strain range of 2.2%–6.1%. For both (Ti-Al3Ti)cs/A356 and Al3Tip/A356 composites, the simulation results are in good agreement with microstructural observations during an in-situ tensile test in a scanning electron microscope.

A bimodal microstructure composed of large primary α-Al phases (PPs) and small secondarily solidified grains (SSGs) is fabricated in 6061 aluminum alloy by powder thixoforming (PTF) method after solution treatment. Artificial aging treatment introduces nanosized precipitates into the bimodal microstructure, in which the number and growth rate of precipitates are different: the number in PPs is larger than that in SSGs due to the higher density of dislocations and lattice distortions in PPs, while the growth rate in SSGs is higher than that in PPs owing to the higher solute concentration in SSGs. As the number and size of precipitates are optimized in the bimodal microstructure, i.e., in peak-aged state, remarkable increments of 56.1% and 130.3% in ultimate tensile strength and yield strength while a moderate increase of 6.3% in ductility are achieved compared with the as-fabricated state, which overcomes the trade-off in strength and ductility of conventional aging-treated 6061 alloys with unimodal microstructure. The strengthening comes from the geometrically necessary dislocations induced by the deformation incompatibility of bimodal microstructure and from precipitate strengthening by nanosized precipitates, while the toughening is from the enhanced dislocation accumulation in this alloy.

Purpose: The purpose of the study was to review and summarize current literature concerning the validation and application of lung ultrasound (LUS) in critically ill patients with acute respiratory distress syndrome (ARDS). Materials and Methods: An extensive literature search was conducted using PubMed, Cochrane Review, Google Scholar, and Ohio State University Link based on the question if LUS should be considered a reliable investigational technique for ARDS diagnosis, treatment, and prognosis in pediatric and adult population. Results: LUS has been successfully validated for facilitating early diagnosis and diagnosis of simultaneous lung conditions, predicting lung recruitment treatment effect, and evaluating the prognosis in ARDS patients. Whether lung US is a useful tool in the prediction of prone position and oxygenation response in patients with ARDS is conflicting. Conclusions: LUS is a noninvasive, radiation-free, cheap, and easy to perform tool for critically ill patients with ARDS and might be a promising technique used in the Intensive Care Unit for ARDS management.

A novel processing technology for the fabrication of particle reinforced metal matrix composites, powder thixoforming (PTF), was proposed and 6061 Al-based composites reinforced with 10% volume fractions of SiC particles (SiCp) were fabricated. The effects of processing parameters, such as reheating time, mould temperature and reheating temperature, on its microstructure and mechanical properties were investigated. The results indicated that all the three processing parameters exerted a significant influence on the microstructure and mechanical properties. The behavior of SiCp changes with the processing parameters. The best comprehensive mechanical properties with an ultimate tensile strength (UTS) of 228 MPa, elongation of 5.3% and a Vickers hardness of 66.4 HV are obtained when the composite is thixoforged under the reheating temperature of 660 0C for 90 min and the mould temperature of 250 0C.

Surgery for laryngeal cancer and the following recurrent tumor growth may further change the anatomy of the airway. Airway management during anesthesia induction is challenging for the patients undergoing secondary surgery due to recurrence of laryngeal cancer or its postoperative complication, but it has never been reported. In this report, we described three cases of anesthetic induction which had different process of airway events. The first case was given intravenous general anesthetic for induction and experienced failed intubation, difficult mask ventilation and emergent tracheostomy, eventually were rescued successfully. The second case presented a fixed metastatic mass about 6 cm diameter upon the primary surgical scar of incision and preoperative apnea, underwent fibroscopy-guided conscious intubation and the process was uneventful. The third case had erythema and swelling under the mandible with erupted ulcer as well as neck immobility due to recurrent tumor. The anesthesiologist attempted fibroscopy-guided intubation via nasal passage with a tracheal tube in 2.8 mm diameter but it was failed. Subsequently, tracheostomy was performed under bilateral superficial cervical plexus block and the dissected larynx by operation verified distorted structure of glottis with S-shaped stenosis. This report concludes that, during the anesthetic induction for this special type of surgery, a detailed and comprehensive evaluation of the airway, and a routine fibroscopic examination are especially important.

Powder thixoforming (PTF) was a promising processing technology that can be used to fabricate high strength particle reinforced aluminum matrix composites, and a pioneer 6061 matrix alloy was fabricated utilizing PTF to investigate its solution treatment behaviors. A comparison study with traditional permanent mold cast (PMC) 6061 alloy disclosed that PTF alloy showed significantly reduced pore amount with only 0.16% (3.50% for PMC alloy). During solution treatment, PTF alloy displayed a much quicker solutionization progress than PMC alloy because of coarse eutectic phases and primary dendrites in latter alloy, its peak values of 14.5%, 241 MPa and 195 MPa in elongation, ultimate tensile strength and yield strength were achieved at 560ºC, an enhancement of 81.3%, 33.9% and 97.0%, respectively, compared with as-fabricated alloy. The dissolution of eutectic phases plays a dominative role in the growth of the primary α phases and secondarily primary α phases within 535ºC. However, the coarsening after 535ºC is subject to a mixture model involving atom diffusion along grain boundaries and through the crystal lattice. The superior tensile strengths of PTF alloy than PMC alloy resulted from decreased grain size, enhanced solid solution strengthening, reduced porosities and decreased harmful effect of insoluble phases in PTF alloy.

In this work, a novel processing method called powder thixoforming was proposed to prepare composites reinforced with 50 vol % of SiC particles (SiCp) that were used for electronic packaging in order to investigate the effects of remelting duration on its microstructure and properties. Optical Microscope (OM), Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) methods were applied for the material characterization and the corresponding physical and mechanical properties were examined in detail. The obtained results indicate that the remelting duration exerted a large effect on the microstructure as well as the SiCp/Al interfacial reaction. The density and hardness of the composite continuously increased with increasing remelting duration. The thermal conductivity (TC) and bending strength (BS) first increased during the initial 90 min and then decreased. The remelting duration exerted a limited influence on the coefficient of thermal expansion (CTE). The optimal TC, BS, and hardness of these composites were up to 135.79 W/(m·K), 348.53 MPa, and 105.23 HV, respectively, and the CTE was less than 6.5 ppm/K after the composites were remelted at 600 °C for 90 min. The properties of the composites could thus be controlled to conform to the application requirements for electronic packaging materials.

Microstructural and mechanical characterization of 10 vol% SiC particles (SiCp) reinforced 6061 Al-based composite fabricated by powder thixoforming (PTF) was investigated in comparison with the PTF and permanent mold cast (PMC) 6061 monolithic alloys. The results reveal that the microstructure of the PMC alloy consists of coarse and equiaxed α dendrites and interdendritic net-like eutectic phases. However, the microstructure of the PTF composite, similar to that of the PTF alloy, consists of near-spheroidal primary particles and intergranular secondarily solidified structures except SiCp, which are distributed in the secondarily solidified structures. The eutectics amount in the PTF materials is distinctly lower than that in the PMC alloy, and the microstructures of the former materials are quite compact while that of the latter alloy is porous. Therefore, the PTF alloy shows better tensile properties than the PMC alloy. Owing to the existence of the SiC reinforcing particles, the PTF composite attains an ultimate tensile strength and yield strength of 230 MPa and 128 MPa, representing an enhancement of 27.8% and 29.3% than those (180 MPa and 99 MPa) of the PTF alloy. A modified model based on three strengthening mechanisms was proposed to calculate the yield strength of the PTF composite. The obtained theoretical results were quite consistent with the experimental data.

A new method, powder thixoforming, has been proposed to fabricate an in situ Al3Tip/2024Al composite. During partial remelting, the microstructural evolution of the bulk alloy prepared by cold pressing of the Ti, Al, 2024Al powder mixture was investigated, and the formation mechanism of the Al3Ti particles produced by the reaction between the Ti powder and the Al alloy melt is also discussed in detail. The results indicate that the microstructural evolution of the 2024 alloy matrix can be divided into three stages: a rapid coarsening of the powder grains; a formation of primary α-Al particles surrounded with a continuous liquid film; and a slight coarsening of the primary α-Al particles. Simultaneously, a reaction layer of Al3Ti can be formed on the Ti powder surface when the bulk is heated for 10 min at 640 °C The thickness (X) of the reaction layer increases with the time according to the parabolic law of \(X = -0.43t^{2} + 4.21t + 0.17\). The stress generated in the reaction layer due to the volume dilatation can be calculated by using the equationσ \(\sigma_{Al_{3}Ti} = -\frac{ E_{Al_{3}Ti} }{6(1-v{Al_{3}Ti})} \frac{ t^{3}_{Al_{3}Ti} }{t_{Ti}} \left(\frac{1}{R} - \frac{1}{R_{0}} \right) \). Comparing the obtained data with the results of the drip experiment, the reaction rate for the Ti powder and Al powder mixture is greater than that for the Ti plate and Al alloy mixture, respectively.

Based on the equivalence relation, we can partition a set U, formally, different equivalence relations correspond to different partitions of U. In this paper, based on Yager's work, we discuss how to compare the different partitions, moreover, we obtain some indexes to select a better partition from given partitions. By an illustrative example, we show that our proposed indexes can be used for selecting partitions, feature selection, and help us to gather more information to decision making.