Synthesis and Characterization of Lignin Grafting Modification-based Aliphatic Superplasticizer

Lignin as the main component of black liquor is generally employed to modify aliphatic superplasticizer（AFS）. However, the modification effect is hard to evaluate correctly due to the uncertain molecular structure of lignin and the disturbance from the complexity of black liquor compositions. In this paper, the purified lignin via acid precipitation from straw black liquor is used to modify AFS. The modified AFS named as LAFS for short presents lower molecular mass than AFS. It is assumed that it is due to the single active site of guaiacol segments in lignin by which lignin graft modifies AFS in virtue of methylolation reaction. In order to verify this assumption, guaiacol and dihydro eugenol as the typical segments of lignin macromolecule were selected, respectively, as the simplified model compounds of lignin to modify AFS, and corresponding products are abbreviated in GAFS and DAFS. Both GAFS and DAFS show the lower molecular mass than unmodified AFS. FTIR and TG-DTG analyses prove that lignin is successfully grafted onto AFS. The graft modification of lignin results in a decrease in electrostatic epulsion, but an enhanced steric hindrance. Therefore, although the replacement rate of lignin in LAFS was about 23.3%, the dispersion performance was only slightly affected.

Cu-Mn catalysts modified by rare earth lantnaum for low temperature water-gas shift reaction

The Cu-Mn catalysts doped with different amounts of lanthanum（La） for water-gas shift reaction（WGSR） were prepared, and characterized by X-ray diffraction（XRD）, temperature-programmed reduction（TPR）, temperature-programmed reduction of oxidized surfaces（s-TPR）, temperature-programmed desorption of CO_2（CO_2-TPD）, infrared spectrum（FT-IR） and X-ray photoelectron spectroscopy（XPS）. Catalytic activities were tested for a water-gas shift reaction. The results showed that the introduction of 0.5 mol.% La could significantly improve the catalyst activity for low-temperature shift reaction compared with the undoped catalyst, which might be from the introduction of La making the Cu and Mn components distribute uniformly and the synergistic effect between Cu and Mn increasing the dispersion of Cu on the surface of the catalyst. The apparent CuO phases besides Cu_（1.5）Mn_（1.5）O_4 were found in the samples with at least 3.0 mol.% La content, and the basic sites increased with the increasing of La contents at a decreased rate. With excessive La doping, La particles would aggregate and cover some active sites, resulting in that Mn could not effectively inhibit the gathering together and growing up of Cu crystalline grain, and decreased the dispersion of Cu on the surface, which resulted in the poor activity of the catalyst for WGSR.

Evaluating the safety benefit of retrofitting motorways section with barriers meeting a new EU standard:Comparison of observational before-after methodologies

The road safety barriers are today designed and installed in compliance with the European standards for Road Restraint Systems （EN 1317）, which lays down common requirements for the testing and certification in all EU countries. The introduction of the European Union （EU） regulation for safety barriers, which is based on performance, has encouraged Euro- pean road agencies to perform an upgrade of the old barriers installed before 2000, with the expectation that there will be safety benefits at the retrofitted sites. Due to the high cost of such treatments, a benefit-cost analysis （BCA） is often used for site selection and ranking and to justify the investment. To this aim a crash modification factor （CMF） has to be applied and errors in the estimation of benefits are directly reflected in the reliability of BCA. Despite the benefits of empirical Bayes before-after （EB-BA） analysis or similar rigorous methods are well-known in the scientific world, these approaches are not always the standard for estimating the effectiveness of safety treatments. To this aim, the dif- ferences between the EB-BA and a naive comparison of observed crashes before and after the treatment are presented in the paper. Crash modification factors for total and target crashes are estimated by performing an EB-BA based on data from a motorway in Italy. As expected the results suggest a strong safety benefit for the ran-off-road crashes by reducing the number of severe crashes （fatal and injury）. The statistical significance of results ob- tained by the EB-BA approach show that the retrofits are still cost-effective. Thecomparison pointed out as selection bias effects can overestimate the safety benefit of the retrofits when a naive approach is used to estimate the CMF and how those can signifi- cantly affect a benefit-cost analysis.