The Effect of Temperatures on the Passivation Behavior of Q235 Steel in the Simulated Concrete Pore Solution.

Concrete, especially mass concrete, releases a large amount of heat during the hydration process, resulting in the passivation of reinforcement at high temperatures. However, the passivation study of reinforced concrete is mostly conducted at room temperature, and the influence of temperature on passive film behavior is not clear at present. The passivation film of reinforcing steel directly determines the corrosion resistance of reinforcing steel and affects the service life of reinforced concrete. Herein, the passivation of Q235 steel soaking in simulated concrete pore (SCP) solution at 20 °C, 40 °C, and 60 °C is explored. It is found that the passivation process is divided into two stages, with 24 h as the boundary; within 24 h the passivation was carried out rapidly, and the passive film is in a relatively stable state after 24 h. In addition, the higher the temperature, the faster the passivation. Moreover, under the condition of higher temperatures, more Fe3+ compounds are produced, and the semiconductor properties of passivated films are more stable. Based on experiments, the passivation mechanism affected by temperature was analyzed in detail.

Multimorbidity and Mortality Models to Predict Complications Following Percutaneous Coronary Interventions.

BACKGROUND: Previous percutaneous coronary intervention risk models were focused on single outcome, such as mortality or bleeding, etc, limiting their applicability. Our objective was to develop contemporary percutaneous coronary intervention risk models that not only determine in-hospital mortality but also predict postprocedure bleeding, acute kidney injury, and stroke from a common set of variables. METHODS: We built risk models using logistic regression from first percutaneous coronary intervention for any indication per patient (n=19 322, 70.6% with acute coronary syndrome) using the Mayo Clinic registry from January 1, 2000 to December 31, 2016. Approval for the current study was obtained from the Mayo Foundation Institutional Review Board. Patients with missing outcomes (n=4183) and those under 18 (n=10) were removed resulting in a sample of 15 129. We built both models that included procedural and angiographic variables (Models A) and precatheterization model (Models B). RESULTS: Death, bleeding, acute kidney injury, and stroke occurred in 247 (1.6%), 650 (4.3%), 1184 (7.8%), and 67 (0.4%), respectively. The C statistics from the test dataset for models A were 0.92, 0.70, 0.77, and 0.71 and for models B were 0.90, 0.67, 0.76, and 0.71 for in-hospital death, bleeding, acute kidney injury, and stroke, respectively. Bootstrap analysis indicated that the models were not overfit to the available dataset. The probabilities estimated from the models matched the observed data well, as indicated by the calibration curves. The models were robust across many subgroups, including women, elderly, acute coronary syndrome, cardiogenic shock, and diabetes. CONCLUSIONS: The new risk scoring models based on precatheterization variables and models including procedural and angiographic variables accurately predict in-hospital mortality, bleeding, acute kidney injury, and stroke. The ease of its application will provide useful prognostic and therapeutic information to both patients and physicians.

Determination of the volatile constituents in radix Flemingiae Philippinensis by GC-MS and a heuristic evolving latent projection method.

With the help of chemometric resolution methods, a technique for qualitative and quantitative determination of the volatile chemical constituents in radix Flemingiae Philippinensis by chromatography-mass spectrometry was developed. After the overlapping chromatographic peaks were resolved into pure chromatograms and spectra using a heuristic evolving latent projections (HELP) method, qualitative analysis was performed by similarity search of the obtained pure mass spectrum of each component in the NIST library and the quantitative results were obtained by calculating the total two-way response volume. A total of 63 components were separated and 55 components were identified, accounting for 90.62% of the total content. The main components were farnesol isomer and beta-caryophyllene, accounting for 31.33% and 12.60% of the total content, respectively. The obtained results can provide useful information for further study and development of radix Flemingiae Philippinensis.

Treatment of high fluoride concentration water by MgAl-CO3 layered double hydroxides: kinetic and equilibrium studies.

MgAl-CO(3) layered double hydroxides (LDHs) have been employed to treat high fluoride concentration solution. The influences of solution pH, initial fluoride concentration and other anions in the solution were investigated by a series of batch experiments. A marked decrease in the amount of adsorbed fluoride by LDHs is observed with increasing pH. The extent of fluoride removal in the presence of other anions decreases in the order HCO(3)(-)>Cl(-)>H(2)PO(4)(-)>SO(4)(2-). The equilibrium isotherm for fluoride uptake corresponds closely to the Langmuir-Freundlich (L-F) model. The maximum capacity of LDHs for fluoride ions and the Gibbs free energy (DeltaG(0)) for the defluoridation process were calculated to be 319.8+/-5.7mg/g and -9.0+/-0.66kJ/mol, respectively. The negative value of DeltaG(0) indicates the spontaneous nature of the treatment process. Four kinetic models have been evaluated in order to attempt to fit the experimental data, namely the pseudo-first order, the pseudo-second order, the modified multiplex and the double exponential models. It was found that the modified multiplex model, involving a rapid first order step and a slow second order step most closely described the kinetics. The activation energies for the two steps are 37.2+/-5.26 and 72.6+/-4.52kJ/mol, respectively, suggesting that the rapid step is controlled by diffusion processes, whilst the second step is controlled by the reaction of fluoride with the LDHs.