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Valve-sparing root replacement (VSRR) requires a unique skill set. This study aimed to examine the influence of surgeon's procedural volume on outcomes of VSRR.

In this study, activated carbon was produced from cypress sawdust by microwave-assisted phosphoric acid activation. Three kinds of metal salts (Fe(NO3)3, Mn(NO3)2and Zn(NO3)2) were used as assisted activating agents to induce carbons’ porosity development. The physico-chemical properties of the produced carbons were characterized, the adsorption performance of the produced carbons toward acid red 88 (AR88) were also evaluated. The results showed that with Fe(NO3)3assisted activation, the produced carbon (FeAC) showed highest BET surface area (1758 m2·g–1) and maximum total pore volume (1.173 cm3·g–1), which is 34.0% and 30.9% higher than those without metal salts assisted activation (AC), respectively. While Mn(NO3)2assisted activation lead to 53.8% increment of mesopore in MnAC, and resulted highest AR88 adsorptive efficiency. Three isotherm models were used to fit the adsorption data, the maximum adsorption capacity of MnAC was found to be 416.67 mg·g–1at 298K according to Langmuir model. The kinetics studies showed that chemical process is involved in the AR88 adsorption. The thermodynamic parameters (ΔH0, ΔS0and ΔG0) showed that the adsorption process was spontaneous and exothermic. The regeneration of MnAC was also evaluated. The result suggested that metal salts assisted activation can effectively turn cypress sawdust to economic and efficient adsorbents for AR88 removal.

In this study, the modified activated coke (AC-Tit) was prepared from coals using titanium ore by the blending method with a one-step carbonization–activation process. The results show that the addition of titanium ore affects the physicochemical properties of AC-Tit. The AC-Tit samples have higher Vmicand Vmic/Vtotratios as well as oxygen and CO functional group. The metal oxides (i.e., FeTiO3, TiO2, Fe2O3, and Fe) were detected on the surface of samples, attributed to the existence of Fe and Ti in the titanium ore. The titanium ore addition improved the desulfurization performance of the AC-Tit effectively; the highest sulfur capacity was 203.3 mg/g, which was much higher than that of the blank sample (120.1 mg/g). After desulfurization, some metal sulfates, i.e., Fe2(SO4)3and CaSO4, were detected on the AC-Tit samples. When the sample was regenerated, its surface area (SBET) and Vmicdid not change significantly, the relative content of CO decreased, and COOH increased evidently. In addition, metal sulfates on the AC-Tit samples were not decomposed during the regeneration process. The variation of surface chemical properties of the regenerated AC-Tit caused the reduction of the desulfurization activity after regeneration.

The regeneration properties of a novel pyrolusite-modified activated coke (ACP) by blending method were investigated. Cyclic regeneration of ACP (ACP-Rn) shows the ACP was a good desulfurizer. The sample had the best desulfurization performance after five regeneration cycles (ACP-R5), and its sulfur capacity was 178 mg/g, 10.8% higher than that of ACP (161 mg/g). The SBETand pore volume were increased with the number of regeneration cycles, but they were not the limiting factors of the SO2removal. The better surface functional groups, especially the basic sites, contributed more to the improvement of desulfurization performance of ACP-Rn. The loaded metals played an important role in SO2removal. The accumulation of metal sulfate in ACP rapidly increased from the first to fifth regeneration cycles and then remained relatively stable during further reuse. The ACP regeneration process divided into three stages: drying, reaction, and pyrolysis. The wrapped metals relatively enhance the pyrolysis and acted as further surface modifications.