The effect of rolling temperature on the incomplete recrystallization behavior and the relationship to mechanical properties in 0.06C–4Mn-1.2Cr (wt.%) steel was investigated. Three plates of ...experimental steel were produced by hot rolling at different temperatures and intercritical annealing processes in this study. The microstructure of experimental steels was examined by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscope (TEM). The mechanical properties of test steel were examined by impact test and tensile test. Austenite reversion and cementite precipitation-dissolution was numerically simulated under the assumption of local equilibrium. With the decrease of hot rolling temperature from 1000 °C to 800 °C, the uniform equiaxed prior austenite grains microstructures changed to heterogeneous microstructures of laminated and ultrafine prior austenite grains arranged alternatively. The tensile and impact tests revealed that the medium manganese steels rolling at 800 °C had an excellent combination of mechanical properties. Elongation had a great relationship with retained austenite fraction and stability. The fractography of impact specimens was examined to explore the toughening mechanism of the micro-laminated steels. The steel with uniform equiaxed grain structure exhibited a relatively low tensile strength of 750 MPa and low elongation of ∼20% and an extremely poor low-temperature toughness of ∼40 J at −40 °C. An enhanced low-temperature toughness (∼233 J at −40 °C), as well as an improved tensile strength (823 MPa) and higher elongation of ∼40%, was obtained in the steel with heterogeneous microstructures. The content of austenite in heterogeneous microstructure is twice that in uniform equiaxed grain structure. And cementite dissolved more thoroughly in the heterogeneous microstructure. The high austenite content of heterogeneous microstructures enabled the steel to be significantly stronger and ductile, which contributed to the high tensile strength and elongation to some extent. It is concluded that the effect of interface decohesion resulted in the occurrence of delamination. And the high austenite content and delamination greatly improved the low-temperature toughness of experimental steel.
The management of postoperative and inflammatory pain has been a pressing challenge in clinical settings. Sinomenine (SN) is a morphinan derived alkaloid with remarkable analgesic properties in ...various kinds of pain models. The aim of the current study is to investigate if SN can enhance the effect of ligustrazine hydrochloride (LGZ) or paracetamol (PCM) in animal models of postoperative and inflammatory pain. And to determine if the combined therapeutic efficacies can be explained by pharmacokinetics changes. Pharmacological studies were performed using a rat model of incisional pain, and a mouse model of carrageenan induced inflammatory pain. Pharmacokinetic studies were performed using a microdialysis sampling and HPLC-MS/MS assay method to quantify SN, LGZ, and PCM levels in blood and extracellular fluid in brain. We found that SN plus LGZ or SN plus PCM produced marked synergistic analgesic effects. However, such synergy was subjected to pain modalities, and differed among pain models. Pharmacological discoveries could be partially linked to pharmacokinetic alterations in SN combinations. Though further evaluation is needed, our findings advocate the potential benefits of SN plus LGZ for postoperative pain management, and SN plus PCM for controlling inflammatory pain.
We investigated the expression of transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) in the liver tissue of infants with congenital biliary atresia and neonatal ...hepatitis, as well as the relationship between the expression of the two factors and liver fibrosis. Thirty-six infants who met the cholestasis criteria were classified into congenital biliary atresia and neonatal hepatitis groups. All specimens were stained with hematoxylin and eosin and Masson's trichrome, and the degree of liver fibrosis was assessed. The scope and level of CTGF and TGF-β1 expression in the different specimens was evaluated by immunohistochemistry and observation. Liver fibrosis in the congenital biliary atresia group was more advanced than that in the neonatal hepatitis group, and the difference was significant (P < 0.01). In the neonatal hepatitis patients, CTGF and TGF-β1 were mainly expressed in the hepatocytes, while they were expressed in both hepatocytes and biliary epithelial cells in the congenital biliary atresia patients, and in these patients the expression was significantly stronger than in the neonatal hepatitis patients (P < 0.01). With the aggravation of hepatic fibrosis, CTGF and TGF-β1 expression levels in liver tissue gradually increased, and their expression levels were significantly correlated (P < 0.01). Liver fibrosis is present in both congenital biliary atresia and neonatal hepatitis patients. The gradual increase of CTGF and TGF-β1 expression levels in liver tissue is associated with liver fibrosis. Early expression of CTGF and TGF-β1 in biliary epithelial cells may be involved in the pathogenesis of congenital biliary atresia.
Peroxisome proliferator-activated receptor (PPAR) signaling pathways have been reported to exert anti-inflammatory effects and attenuate atherosclerosis formation. However, the mechanisms responsible ...for their anti-inflammatory and antiatherosclerotic effects remain largely unknown. The present study tested the hypothesis that a PPARgamma agonist may exert significant endothelial protection by antioxidative and antinitrative effects.
Male New Zealand White rabbits were randomized to receive a normal (control) or a high-cholesterol diet and treated with vehicle or rosiglitazone (a PPARgamma agonist) 3 mg x kg(-1) x d(-1) for 5 weeks beginning 3 weeks after the high-cholesterol diet. At the end of 8 weeks of a high-cholesterol diet, the rabbits were killed, and the carotid arteries were isolated. Bioactive nitric oxide was determined functionally (endothelium-dependent vasodilatation) and biochemically (the phosphorylation of vasodilator-stimulated phosphoprotein, or P-VASP). Vascular superoxide production, PPARgamma, gp91phox, and inducible nitric oxide synthase (iNOS) expression, and vascular ONOO- formation were determined. Hypercholesterolemia caused severe endothelial dysfunction and reduced P-VASP, despite a marked increase in iNOS expression and total NOx production. Treatment with rosiglitazone enhanced PPARgamma expression, improved endothelium-dependent vasodilatation, preserved P-VASP, suppressed gp91phox and iNOS expression, reduced superoxide and total NOx production, and inhibited nitrotyrosine formation.
The PPARgamma agonist rosiglitazone exerted a significant vascular protective effect in hypercholesterolemic rabbits, most likely by attenuation of oxidative and nitrative stresses. The endothelial protective effects of PPARgamma agonists may reduce leukocyte accumulation in vascular walls and contribute to their antiatherosclerotic effect.
A micromechanics model for three-dimensional (3D) open-cell foams is developed by using the matrix method for spatial frames and tetrakaidecahedral unit cells. The effective elastic properties of ...foams are determined utilizing unit cells subjected to loadings of three different modes. The newly obtained member stiffness submatrices for a 3D frame member undergoing simultaneous axial, transverse shearing, flexural and torsional deformations and having a circular or non-circular cross-section are employed. The use of these stiffness submatrices enables the incorporation of all four deformation mechanisms (i.e., stretching, shearing, bending and twisting) possible under the specified loadings and the treatment of four different strut cross-section shapes (i.e., circle, square, equilateral triangle and Plateau border) in a unified manner. The formulas for determining the effective Young's moduli, Poisson's ratios and shear moduli of open-cell foams are derived using the composite homogenization theory. The new formulas, in which the cell displacements are obtained employing the matrix method, include all necessary microstructural and material parameters, unlike those provided by existing models. It is shown that the foam elastic properties depend on the relative foam density, the shape and size of the strut cross-section, and the Young's modulus and Poisson's ratio of the strut material. By applying the new model, a parametric study of sample cases involving the three loading modes and the four strut cross-section shapes is conducted for carbon foams, whose modeling motivated this work. The predicted values of the effective properties agree favorably with those based on existing models and experimental data for the Mode I loading case, which is the only case that has been well studied. For the Mode II and Mode III loading cases, the formulas and the subsequent sample results are presented in a systematic manner for the first time. Comparisons of the predicted effective elastic properties for the three loading cases quantitatively show that carbon foams exhibit certain degrees of anisotropy.
Cerebral resuscitation after cardiac arrest (CA) is always an unresolved problem in medical field. The decreased cerebral perfusion or nonperfusion caused by coagulation and fibrinolytic system ...function disorder and cerebral microthrombosis after CA and cardiopulmonary resuscitation (CPR) is one of the important reasons.
TTo investigate the effect of urokinase on cerebral microcirculatory perfusion after CA and CPR in rabbits. 20 rabbits were randomly divided into experimental group and control group, 10 rabbits in each group. Potassium chloride injection combined with asphyxia method was conducted to establish the CA models. CPR and basic life-support were performed on experimental group. Based on above treatments, intervention with urokinase was conducted on experimental group. Dual-slice spiral CT cerebral perfusion imaging was performed to observe the cerebral blood flow (CBF), cerebral blood volume (CBV) and top teep time (TTP).
CBF and CBV in experimental group were significantly higher than those in control group, respectively (p < 0.01), and TTP in experimental group was significantly shorter than control group (p < 0.01). The cerebral perfusion in experimental group was better than control group.
Thrombolytic therapy with urokinase in CPR after CA can improve the cerebral microcirculatory perfusion in rabbits.
Synopsis The fragmentation dynamics of nitrogen molecule dimers have been studied by using highly charged Ne8+ ions at impact energy of 1.0 MeV. For its three-body fragmentation, three fragmentation ...mechanisms have been identified by analyzing Dalitz plot and Newton diagram of the momenta of three fragment ions. The sequential dissociation of covalent first breakdown is quite surprising in contrast to the fragmentation of triatomic molecule.
Ni–Mn–Ga thin films have been fabricated by using magnetron sputtering technique under various substrate negative bias voltages. The effect of substrate negative bias voltage on the compositions and ...surface morphology of Ni–Mn–Ga thin films was systematically investigated by energy dispersive X-ray spectrum and atomic force microscopy, respectively. The results show that the Ni contents of the thin films increase with the increase of the substrate negative bias voltages, whereas the Mn contents and Ga contents decrease with the increase of substrate negative bias voltages. It was also found that the surface roughness and average particle size of the thin films remarkably decrease with the increase of substrate negative bias voltages. Based on the influence of bias voltages on film compositions, a Ni
56Mn
27Ga
17 thin film was obtained at the substrate negative bias voltage of 30
V. Further investigations indicate that the martensitic transformation start temperature of this film is up to 584
K, much higher than room temperature, and the film has a non-modulated tetragonal martensitic structure at room temperature. Transmission electron microscopy observations reveal that microstructure of the thin film exhibits an internally (1
1
1) type twinned substructure. The fabrication of Ni
56Mn
27Ga
17 high-temperature shape memory alloy thin film will contribute to the successful development of microactuators.
A dedicated platform for multi-disciplinary research with highly charged ions has been constructed, and an all-permanent magnet ECR ion source was built and installed in the beamline. Five ...experimental terminals are established for interdisciplinary Research. The high voltage supplied to the platform has reached 320 kV. The commissioning of the platform is successful, different ion beams have been provided for experimental studies, and the current status will be reported.
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