Application of homogeneous potentials for the modeling of the Bauschinger effects in ultra low carbon steel

In this work, an approach is proposed for the description of the plastic behavior of materials subjected to multiple or continuous strain path changes. In particular, although it is not formulated with a kinematic hardening rule, it provides a reasonable description of the Bauschinger effect when loading is reversed. This description of anisotropic hardening is based on homogeneous yield functions/plastic potentials combining a stable, isotropic hardening-type, component and a fluctuating component. The capability of this constitutive description is illustrated with applications on an ultra low carbon steel sheet sample deformed in three-stage uniaxial loading with two load reversals [1].ope

Impact of Blood Pressure on Allograft Function and Survival in Kidney Transplant Recipients

The optimal target blood pressure for kidney transplant (KT) patients remains unclear. We included 808 KT patients from the KNOW-KT as a discovery set, and 1,294 KT patients from the KOTRY as a validation set. The main exposures were baseline systolic blood pressure (SBP) at 1 year after KT and time-varying SBP. Patients were classified into five groups: SBP <110; 110–119; 120–129; 130–139; and ≥140 mmHg. SBP trajectories were classified into decreasing, stable, and increasing groups. Primary outcome was composite kidney outcome of ≥50% decrease in eGFR or death-censored graft loss. Compared with the 110–119 mmHg group, both the lowest (adjusted hazard ratio [aHR], 2.43) and the highest SBP (aHR, 2.25) were associated with a higher risk of composite kidney outcome. In time-varying model, also the lowest (aHR, 3.02) and the highest SBP (aHR, 3.60) were associated with a higher risk. In the trajectory model, an increasing SBP trajectory was associated with a higher risk than a stable SBP trajectory (aHR, 2.26). This associations were consistent in the validation set. In conclusion, SBP ≥140 mmHg and an increasing SBP trajectory were associated with a higher risk of allograft dysfunction and failure in KT patients

Evaluation of anisotropic hardening models using two-steps tension tests

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Enhancement of the electrochemical performance in LiFePO4 cathode materials synthesized by using the sol-gel method

LiFePO4 powders were synthesized by using the sol-gel and the solid-state reaction methods. The chemical states of Fe ions were studied by using XPS, and their electrochemical properties according to the oxidation states of Fe ions were compared. The average oxidation state of Fe ions in LiFePO4 powders synthesized by using the solid-state reaction method was found to be Fe3+, on the other hand, that of Fe ions synthesized by using the sol-gel method was found to be Fe2+. The obtained discharge capacities were 50 mAh/g and 120 mAh/g at a rate 0.1 C in LiFePO4 synthesized by using the solid-state reaction and sol-gel methods, respectively. Relatively a good cycling stability was observed in sol-gel prepared powder

Second harmonic generation and fabrication of transparent K2O-Na2O-Nb2O5-TeO2 glass-ceramics

To develop and utilize TeO2-based glasses as nonlinear optical materials or matrix glasses, xK2O- (14-x)Na2O-14Nb2O5-72TeO2 (x=0???14 mol%) glasses were prepared using a conventional melt quenching method and then the nano-crystallization behavior and second harmonic generation (SHG) properties of these glasses were investigated. Although SHG was clearly observed in 10K2O-4Na2O-14Nb2O5-72TeO2 glassceramics consisting of a nano-crystalline phase, the 14Na2O-14Nb2O5-72TeO2 glass-ceramic exhibited no SHG. K+ ions played an important role in inducing SHG in the K2O-Na2O-Nb2O5-TeO2 system.close0

Removal of Heavy Metal Ions by using Calcium Carbonate Extracted from Starfish Treated by Protease and Amylase

CaCO3 extracted from starfish by using the commercial protein lyase having α-amylase, β-amylase, and protease is applied to remove heavy metal ions. The extracted CaCO3 shows excellent characteristics in removing heavy metal ions such as Cu2+, Cd2+, Pb2+, and Cr6+ compared with conventional materials such as crab shells, sawdust, and activated carbon except for removing Zn2+. SEM images reveal that the extracted CaCO33 has a good morphology and porosity. We characterize the removal efficiencies of the extracted CaCO3 for the heavy metal ions according to the concentrations, pH, temperatures, and conditions of empty bed contact times

Thermal stabilities, physical and optical properties of (KO)-O-2-(NaO)-O-2-(NbO5)-O-2-TeO2 glasses

The thermal stabilities, physical and optical properties of xK(2)O-(14-x)Na2O-14Nb(2)O(5)-72TeO(2) (x = 0 similar to 12 mol%) glasses have been studied. The glasses consisting of ca. 10 mol% K2O show high thermal stabilities with values of Delta T = Tx - Tg = ca. 105 degrees C against crystallization, where Tg and Tx are the glass transition and crystallization onset temperatures, respectively. The activation energy of grain growth of a cubic crystalline phase in the 10K(2)O-4Na(2)O-14Nb(2)O(5)-72TeO(2) glass was 7.92 kJ/mol. The energy required for the phase transformation from the 10K(2)O-4Na(2)O-14Nb(2)O(5)-72TeO(2) glass to the cubic crystalline phase was 190.74 kJ/mol. The optical and physical properties of the K2O-Na2O-Nb2O5-TeO2 glasses were obtained: refractive index, n = 1.88-1.97; rho = 4.22-4.64 g/cm(3); optical energy band of the transmission cut-off wavelength, Eg (eV) = 3.17-3.14; relative permittivity, epsilon(r,) = 28-29. The values of R-M and alpha(m) for K2O-Na2O-Nb2O5-TeO2 glasses were much larger than those of Na2O-Nb2O5-TeO2 glassesclose2

Enhanced Photocatalytic Properties due to Electron-rich Ti-ion Doping in ZnFe(2)O(4) under Visible Light Irradiation

The substitution effect of Ti4+ at the Fe3+ site in the spinel-phase ZnFe2O4 system has been studied and further optimized to fabricate an efficient photocatalyst. The material doped with an electron donor (Ti+4), ZnFe2-xTixO4, with an optimum composition of x = 0.06 exhibited a unchanged band gap, which generated two times higher photocurrent and showed an enhanced quantum yield (upto 0.77%) for photodecomposition of a H2O-CH3OH mixture compared to the undoped material under a visible light (lambda >= 420 nm). In contrast, the material doped with very high concentration of Ti revealed deteriorated photochemical properties due to constituent impurity phases. The higher electron density caused by n-type doping seemed to be responsible for the more efficient charge separation in ZnFe2-xTixO4 (0.01 < x < 0.09), and hence, the high photocatalytic activityclose13

Photocatalytic Performance of Nanocrystalline Bi5Ti3FeO15 Layered Perovskite Under Visible Light

[No abstract available]close0