ABSTRACT
Three types of Co3O4 catalyst, namely Co3O4 nanoparticles (denoted as Co3O4-NPs, â¼12 nm in diameter), Co3O4 nanoparticles encapsulated in mesoporou s SiO2 (denoted as Co3O4@SiO2), and Co3O4 nanoparticles inside microporous SiO2 hollow sub-microspheres (denoted as Co3O4-in-SiO2), were explored to catalyze the combustion of lean methane. It was found that the methane conversion over the three catalysts has the order of Co3O4-NPs ≈ Co3O4@SiO2 > Co3O4-in-SiO2 due to the different catalyst structure. The comparison experiments at high temperatures indicate the Co3O4@SiO2 has a significantly improved anti-sintering performance. Combined with the TEM and BET measurements, the results prove that the presence of the mesoporous SiO2 layer can maintain the catalytical activity and significantly improve the anti-sintering performance of Co3O4@SiO2. In contrast, the microporous SiO2 layer reduces the catalytical activity of Co3O4-in-SiO2 possibly due to its less effective diffusion path of combustion product. Thus, the paper demonstrates the pore size of SiO2 layer and catalyst structure are both crucial for the catalytical activity and stability.
ABSTRACT
BACKGROUND: Delayed intracranial hemorrhage (DICH), a potential complication of ventriculoperitoneal (VP) shunts, has been associated with high mortality, but its risk factors are still unclear. AIM: To investigate the risk factors of DICH after VP shunts. METHODS: We compared the demographic and clinical characteristics of DICH and non-DICH adult patients with VP shunts between January 2016 and December 2020. RESULTS: The 159 adult VP shunt patients were divided into 2 groups according to the development of DICH: the DICH group (n = 26) and the non-DICH group (n = 133). No statistically significant difference was found in age, sex, laboratory examination characteristics or preoperative modified Rankin Scale (mRS) score between the DICH and non-DICH groups (P > 0.05); however, a history of an external ventricular drain (EVD) [P = 0.045; odds ratio (OR): 2.814; 95%CI: 1.024-7.730] and postoperative brain edema around the catheter (P < 0.01; OR: 8.397; 95%CI: 3.043-23.171) were associated with a high risk of DICH. A comparison of preoperative mRS scores between the DICH group and the non-DICH group showed no significant difference (P = 0.553), while a significant difference was found in the postoperative mRS scores at the 3-mo follow-up visit (P = 0.024). CONCLUSION: A history of EVD and postoperative brain edema around the catheter are independent risk factors for DICH in VP shunt patients. DICH patients with a high mRS score are vulnerable to poor clinical outcomes.
ABSTRACT
A comparative study of the metal emulsion-based synthesis of Sn-based materials in two different types of molten salts (namely LiCl-KCl-CsCl and LiNO3-NaNO3-KNO3 eutectics) is presented, and the properties of Sn, Sn-Cu and Sn-Cu-Zn microsphere phase change materials prepared in chloride salts are evaluated by differential scanning calorimetry (DSC) to understand the effect of element doping. Despite a high ultrasonic power (e.g., 600 W or above) being required for dispersing liquid Sn in the chloride system, well-shaped Sn microspheres with a relatively narrow size range, e.g., about 1 to 15 µm or several micrometers to around 30 µm, can be prepared by adjusting the ultrasonic power (840-1080 W), sonication time (5-10 min) and the volume ratio of salts to metal (25:1-200:1). Such a method can be extended to the synthesis of Sn-based alloy microspheres, e.g., Sn-Cu and Sn-Cu-Zn microspheres. In the nitrate system, however, a very low ultrasonic power (e.g., 12 W) can be used to disperse liquid Sn, and the particles obtained are much smaller. At low ultrasonic power (e.g., 12 W), the particle size is generally less than 10 or 4 µm when the sonication time reaches 2 or 5 min, and at high ultrasonic power, it is typically in the range of hundreds of nanometers to 2 µm, regardless of the change in ultrasonic power (480-1080 W), irradiation time (5-10 min), or volume ratio of salts to metal (25:1-1000:1). In addition, the appearance of a SnO phase in the products prepared under different conditions hints at the occurrence of a reaction between Sn droplets and O2 in situ generated by the ultrasound-induced decomposition of nitrates, and such an interfacial reaction is believed to be responsible for these differences observed in two different molten salt systems. A DSC study of Sn, Sn-Cu, and Sn-Cu-Zn microspheres encapsulated in SiO2 reveals that Cu (0.3-0.9 wt.%) or Cu-Zn (0.9 wt.% Cu and 0.6% Zn) doping can raise the onset freezing temperature and thus suppress the undercooling of Sn, but a broad freezing peak observed in these doped microspheres, along with a still much higher undercooling compared to those of reported Sn-Cu or Sn-Cu-Zn solders, suggests the existence of a size effect, and that a low temperature is still needed for totally releasing latent heat. Since the chloride salts can be recycled by means of the evaporation of water and are stable at high temperature, our results indicate that the LiCl-KCl-CsCl salt-based metal emulsion method might also serve as an environmentally friendly method for the synthesis of other metals and their alloy microspheres.
ABSTRACT
The prevalence of nasopharyngeal carcinoma (NPC) is higher in southern China, Hong Kong, and Taiwan than in other areas in the world. Radiotherapy is an important part of treatment for NPC patients, especially those with stage III/IV disease. Subdural empyema is a rare but life-threatening complication in postradiotherapy NPC patients which should be paid more attention. Here, we present the case of a 64-year-old female postradiotherapy NPC patient with subdural empyema complicated with intracranial hemorrhage. She was treated by burr-hole surgery but unfortunately died because of recurrent intracranial hemorrhage. The mechanisms potentially underlying the formation of subdural empyema in postradiotherapy NPC patients and the surgical strategies that can be used in these patients are discussed in this report.
