Comparative study between remifentanil (or fentanyl) and dexmedetomidine for the analgesia of rhinoplasty: A meta-analysis of randomized controlled trials.

BACKGROUND: Remifentanil (or fentanyl) and dexmedetomidine may have some potential to improve the analgesia of rhinoplasty, and this meta-analysis aims to compare their efficacy for the analgesia of rhinoplasty. METHODS: PubMed, Embase, Web of Science, EBSCO, and Cochrane Library databases were systematically searched, and we included randomized controlled trials (RCTs) assessing the analgesic effect of remifentanil (or fentanyl) versus dexmedetomidine for rhinoplasty. RESULTS: Four RCTs were finally included in the meta-analysis. In patients undergoing rhinoplasty, remifentanil (or fentanyl) infusion and dexmedetomidine infusion resulted in similar good patient satisfaction (odd ratio [OR] = 2.71; 95% confidence interval [CI] = 0.63 to 11.64; P = .18), good surgeon satisfaction (OR = 1.68; 95% CI = 0.02 to 181.40; P = .83), extubation time (mean difference [MD] = 7.56; 95% CI = -11.00 to 26.12; P = .42), recovery time (MD = -2.25; 95% CI = -23.41 to 18.91; P = .83), additional analgesic requirement (OR = 0.16; 95% CI = 0 to 8.65; P = .37) and adverse events (OR = 8.50; 95% CI = 0.47 to 153.30; P = .15). CONCLUSIONS: Remifentanil (or fentanyl) and dexmedetomidine may have comparable analgesia for patients undergoing rhinoplasty.

A Novel Al-Cu Composite with Ultra-High Strength at 350 °C via Dual-Phase Particle Reinforced Submicron-Structure.

Thermal stability determines a material's ability to maintain its performance at desired service temperatures. This is especially important for aluminum (Al) alloys, which are widely used in the commercial sector. Herein, an ultra-strong and heat-resistant Al-Cu composite is fabricated with a structure of nano-AlN and submicron-Al2 O3 particles uniformly distributed in the matrix. At 350 °C, the (8.2AlN+1Al2 O3 )p /Al-0.9Cu composite achieves a high strength of 187 MPa along with a 4.6% ductility under tension. The high strength and good ductility benefit from strong pinning effect on dislocation motion and grain boundary sliding by uniform dispersion of nano-AlN particles, in conjunction with the precipitation of Guinier-Preston (GP) zones, enhancing strain hardening capacity during plastic deformation. This work can expand the selection of Al-Cu composites for potential applications at service temperatures as high as ≈350 °C.

Effect of Cold and Warm Rolling on the Particle Distribution and Tensile Properties of Heterogeneous Structured AlN/Al Nanocomposites.

Recently, heterogeneous structured metals have attracted extensive interest due to their exciting mechanical properties. In this work, an AlN/Al nanocomposite with heterogeneous distribution of AlN nanoparticles was successfully prepared by a liquid-solid reaction method combined with subsequent extrusion deformation, which behaves an excellent synergy of tensile strength and ductility. In order to further reveal the particle distribution evolution and the tensile property response during further deformation, a series of rolling treatments with different thickness reductions under room temperature and 300 °C was carried out. The results show that the yield strength and tensile strength of the composites increase significantly from 238 MPa, 312 MPa to 312 MPa, 360 MPa after 85% rolling reduction at 300 °C. While the elongation decreased from 15.5% to 9.8%. It is also noticed that the elongation and tensile strength of the nanocomposites increases simultaneously with increasing deformation. It is considered that the aluminum matrix strengthening effect accounts for the strength enhancement. The AlN spatial distribution in the matrix becomes more homogeneous gradually during the rolling, which is supposed to reduce the stress concentration between the particle and matrix and then promote the ductility increase.

Microstructures and Mechanical Properties of Commercially Pure Ti Processed by Rotationally Accelerated Shot Peening.

Gradient structured materials possess good combinations of strength and ductility, rendering the materials attractive in industrial applications. In this research, a surface nanocrystallization (SNC) technique, rotationally accelerated shot peening (RASP), was employed to produce a gradient nanostructured pure Ti with a deformation layer that had a thickness of 2000 µm, which is thicker than those processed by conventional SNC techniques. It is possible to fabricate a gradient structured Ti workpiece without delamination. Moreover, based on the microstructural features, the microstructure of the processed sample can be classified into three regions, from the center to the surface of the RASP-processed sample: (1) a twinning-dominated core region; (2) a "twin intersection"-dominated twin transition region; and (3) the nanostructured region, featuring nanograins. A microhardness gradient was detected from the RASP-processed Ti. The surface hardness was more than twice that of the annealed Ti sample. The RASP-processed Ti sample exhibited a good combination of yield strength and uniform elongation, which may be attributed to the high density of deformation twins and a strong back stress effect.

Microstructure Evolution and Mechanical Properties of Al-TiB2/TiC In Situ Aluminum-Based Composites during Accumulative Roll Bonding (ARB) Process.

In this study, a kind of Al-TiB2/TiC in situ composite was successfully prepared using the melt reaction method and the accumulative roll-bonding (ARB) technique. The microstructure evolution of the composites with different deformation treatments was characterized using field emission scanning electron microscopy (FESEM) and a transmission electron microscope (TEM). The mechanical properties of the Al-TiB2/TiC in situ composite were also studied with tensile and microhardness tests. It was found that the distribution of reinforcement particles becomes more homogenous with an increasing ARB cycle. Meanwhile, the mechanical properties showed great improvement during the ARB process. The ultimate tensile strength (UTS) and microhardness of the composites were increased to 173.1 MPa and 63.3 Hv after two ARB cycles, respectively. Furthermore, the strengthening mechanism of the composite was analyzed based on its fracture morphologies.

Fabrication of Al/Mg/Al Composites via Accumulative Roll Bonding and Their Mechanical Properties.

Al(1060)/Mg(AZ31)/Al(1060) multilayered composite was successfully produced using an accumulative roll bonding (ARB) process for up to four cycles at an elevated temperature (400 °C). The microstructure evolution of the composites and the bonding characteristics at the interfaces between Al and Mg layers with increasing ARB cycles were characterized through optical microscopy, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). It was found that the grains of Al and Mg layers were significantly refined and Al3Mg2 and Al12 Mg17 intermetallic compound layers formed at the Al/Mg bonding interfaces. The strength increased gradually and the ultimate tensile strength (UTS) reached a maximum value of about 240 MPa at the third pass. Furthermore, the strengthening mechanism of the composite was analyzed based on the fracture morphologies.

[Kinetic mechanisms of glycerol dehydrogenase and 1,3-propanediol oxidoreductase from Klebsiella pneumoniae].

The kinetic mechanisms of two key enzymes in the biotransformation of glycerol to 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae, glycerol dehydrogenase (GDH) and 1,3-propanediol oxidoreductase (PDOR), was characterized. Kinetics on initial velocity and product inhibition revealed that GDH and PDOR follow an ordered Bi-Bi sequential mechanism. Kinetic models for GDH and PDOR showed that the oxidation reaction catalyzed by GDH was the rate-limiting step in coupled enzymatic reaction when the GDH/PDOR was 1:1, and the NAD+ was the main form of coenzyme in the reaction. Knowledge about the kinetic mechanisms will be helpful to understand how these enzymes is regulated, which will be useful for further enzyme catalysis and metabolic engineering studies.