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Sulfate resistance is evaluated in mortars containing sulfate-resistant cementitious materials (SRCMs) developed by mixing ground granulated blast furnace slag, fly ash, silica fume and desulfurisation gypsum. Compressive strength testing, X-ray diffraction analysis, differential thermal analysis and mercury intrusion porosimetry are carried out. Results show that the sulfate resistance of mortars mixed with SRCMs at a replacement percentage of 74 wt% is superior to that of mortars with 30 wt% fly ash when exposed to drying–wetting cycles in sodium sulfate solution, because adding SRCMs decreases the calcium hydroxide content, causing a reduction in gypsum formation. Moreover, reducing the water-to-binder ratio (W/B) from 0.50 to 0.35 increases the loss of compressive strength ratio (Lf) of mortars with SRCMs immersed in ammonium–magnesium sulfate complex solution. Specifically, the Lf values of mortars with W/B of 0.50 and 0.35 are 42.7% and 36.0% after 100 days of immersion, respectively. Furthermore, the main component of samples subjected to complex solution is identified as gypsum. In addition, both Lf and porosity exhibit a strong linear positive correlation with W/B. Finally, the findings confirm that optimising the composition of cementitious materials and lowering W/B could improve the sulfate resistance of concretes used for a sulfate-rich sewage environment. [ABSTRACT FROM AUTHOR]

Ground granulated blast-furnace slag (GGBFS) is well known to be capable of improving the performance of cement-based materials, but few studies focus on the impact of its large dosage on concrete containing basalt powder. In this study, the compressive strength and chloride permeability of cement-based materials with compound mineral admixtures (CMAs) containing high-volume GGBFS, basalt powder and desulfurisation gypsum were investigated. The results showed that the mortar strengths at 3, 7 and 28 days decreased with increasing GGBFS content, but that at 56 and 84 days increased with the addition of 45 wt% GGBFS. This is because the activity of GGBFS at an early stage has not been stimulated and the pozzolanic effect is exerted at a later stage. Moreover, cement replacement with up to 55 wt% GGBFS caused a significant decrease in the chloride diffusion coefficient of the mortar and concrete. Furthermore, the incorporation of GGBFS led to a remarkable refinement in pore structure of the hardened paste due to pozzolanic and filler effects. Therefore, the partial replacement of cement with high CMA contents (≥70 wt%) in concrete is desirable for ocean projects requiring low chloride permeability, and significantly reduces carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

To restore the integrity of the degraded concrete structure in marine environment effectively a marine cementitious repair material-MM was developed and its properties were tested and ordinary cement repair material OM was used as a control. Results showed that the flexural strength the compressive strength and the bond strength of MM were 45%-80% about 100% and 25%-35% higher than those of OM within 90 days respectively. At the same time the electric flux of 28 d MM was 20% of OM indicating relatively good resistance to chloride ion penetration. Moreover the calcium hydroxide content of MM was much lower than that of OM and the hydration product composition at the bonding interface of MM may be improved compared to OM. [ABSTRACT FROM AUTHOR]

In order to accurately localize the image coordinates and serial numbers of intraoperative subdural matrix electrodes, a matrix electrode localization algorithm for image processing is proposed in this paper. Firstly, by using point-by-point extended electrode location algorithm, the electrode is expanded point-by-point vertically and horizontally, and the initial coordinates and serial numbers of each electrode are determined. Secondly, the single electrode coordinate region extraction algorithm is used to determine the best coordinates of each electrode, so that the image coordinates and serial numbers of all electrodes are determined point-by-point. The results show that the positioning accuracy of electrode serial number is 100%, and the electrode coordinate positioning error is less than 2 mm. The algorithms in this paper can accurately localize the image coordinates and the serial numbers of a matrix electrode arranged in an arc, which could aid drawing of cortical function mapping, and achieve precise positioning of brain functional areas, so that it can be widely used in neuroscience research and clinical application based on electrocorticogram analysis.

The main shortcomings of using electrocortical stimulation (ECS) in identifying the motor functional area around the focus in neurosurgery are certainly time-consuming, possibly cerebral cortex injuring and perhaps triggering epilepsy. To solve these problems, we in our research presented an intraoperative motor cortex functional mapping based on electrocorticography (ECoG). At first, using power spectrum estimation, we analyzed the characteristic of ECoG which was related to move task, and selected Mu rhythm as the move-related feature. Then we extracted the feature from original ECoG by multi-resolution wavelet analysis. By calculating the sum value of feature in every channel and observing the distribution of these sum values, we obtained the correlation between the cortex area under the electrode and motor cortex functional area. The results showed that the distribution of the relationship between the cortex under the electrode and motor cortex functional area was almost consistent with those identified by ECS which was called as the gold-standard. It indicated that this method was basically feasible, and it just needed five minutes totally. In conclusion, ECoG-based and passive identification of motor cortical function may serve as a useful adjunct to ECS in the intraoperative mapping.