Effects of promoters on catalytic performance of Fe-Co/SiO_2 catalyst for Fischer-Tropsch synthesis

2%Fe-10%Co/SiO2 catalysts with different potassium or zirconium loadings were prepared by aqueous incipient wetness impregnation and tested for Fischer-Tropsch synthesis in a flow reactor, using H2/CO = 1.6 （molar ratio） in the feed, under the condition of an overall pressure of 1 MPa, GHSV of 600 h^-1 and temperature of 503 K. The zirconium and potassium promoters remarkably influenced hydrocarbon distribution of the products. CO conversion increased on the catalysts with the increase of zirconium loadings, which indicated that zirconium enhanced the activity of iron-cobalt catalysts. Low potassium loadings also enhanced the activity of the catalysts. However, high potassium loading made CO conversion on the catalysts decrease and weakened the secondary hydrogenations. The catalyst was characterized by BET, XRD and TPR. The catalyst characterization revealed that the Co3O4 phase was presented on the fresh catalyst, whereas the spinel phase of Fe-Co alloy and CoO existed on the used catalyst.

Effects of the ratio of Fe to Co over Fe-Co/SiO_2 bimetallic catalysts on their catalytic performance for Fischer-Tropsch synthesis

The Fe-Co/SiO2 bimetallic catalysts with different ratios of Fe to Co were prepared by aqueous incipient wetness impregnation. The catalysts of 10%Fe：0%Co/SiO2, 10%Fe：6%Co/SiO2, 10%Fe：2%Co/SiO2, 10%Fe：10%Co/SiO2, 6%Fe：10%Co/SiO2, 2%Fe：10%Co/SiO2 and 0%Fe： 10%Co/SiO2 by mass were tested in a fixed reactor by the Fischer-Tropsch synthesis. Activity and hydrocarbon distribution were found to be determined by the ratio of iron to cobalt of the catalysts. Higher iron content inhibited the activity, whereas higher cobalt content enhanced the activity of the Fe-Co/SiO2 catalysts. On the other hand, for the catalysts of 10%Fe：6%Co/SiO2, 10%Fe：10%Co/SiO2, 6%Fe：10%Co/SiO2, and 2%Fe：10%Co/SiO2, the total C2-C4 fraction increased （from 10.65% to 26.78%） and C5＋ fraction decreased （from 75.75% to 57.63%） at 523 K. Temperature programmed reduction revealed that the addition of cobalt enhanced the reducibility of the Fe-Co/SiO2 catalyst. Metal oxides were present in those catalysts as shown by XRD. The Fe-Co alloy phase was found in the 2%Fe：10%Co/SiO2, 6%Fe：10%Co/SiO2, 10%Fe： 10%Co/SiO2, 10%Fe：6%Co/SiO2 catalysts and their crystals were perfect.

Peritoneal cancer index is a prognostic indicator of survival in advanced gastric cancer with peritoneal carcinomatosis

Objective The peritoneal cancer index(PCI)has been used for the detailed evaluation of the peritoneal spread in tumors of a gynecologic origin and has been found to be a prognostic indicator of survival.The aim of this study was to identify the significance of the PCI in advanced gastric cancer(AGC)with peritoneal carcinomatosis(PC).Methods From 2010 to 2018,a retrospective analysis was carried out of 60 AGC patients with PC,including 21 patients with a PCI≤13 and 39 with a PCI>13.All patients were treated with both surgery and intraoperative peritoneal hyperthermic chemotherapy(IPHC).The performance status(Karnofsky performance status),age,sex,Borromann’s classification,differentiation,depth of invasion,lymph node metastasis,PCI,extent of gastrectomy,extent of lymph node dissection,and residual tumor volume were retrospectively evaluated and correlated to survival.Results The overall 5-year survival rate was 43%and mean survival was(54.47±4.53)months.The favorable clinical prognostic indicators of survival were Borromann’s classification,differentiation,depth of invasion,PCI,and residual tumor volume on univariate analyses(P<0.05).The Cox proportional regression hazard model showed that only the volume of residual tumor and PCI were associated with postoperative survival.The median survival time was 69.76 months for patients with a PCI≤13 and 39.96 months for patients with a PCI>13.There was a significant difference in survival rate between the two group(P=0.004).Postoperative major morbidity and mortality rates were 23.81%and 4.76%in the PCI≤13 group and 43.59%and 5.12%in the PCI>13 group,respectively.Conclusion The peritoneal spread in advanced gastric cancer with peritoneal carcinomatosis can be assessed in detail using the PCI.It is also a significant prognostic factor of survival and is useful in identifying subgroups.

Doping sites modulation of T-Nb_(2)O_(5) to achieve ultrafast lithium storage

Heteroatoms doping has been regarded as a promising route to modulate the physiochemical properties of electrode materials,in which the doping sites greatly influence the electrochemical performances.However,very few reports focus on enhancing the lithium storage performances of Nb_(2)O_(5) via heteroatoms doping,yet the effect of different doping sites remains unclear.Herein,nitrogen doping has been proposed to improve the fast-charging capability of orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))via a urea-assisted annealing process.Experimental data and theoretical calculation demonstrate that the N doping sites in T-Nb_(2)O_(5) can be tuned by the heating rate,in which substitutional N can increase the spacing of the Li^(+)transport layer as well as reduce the band gap,while interstitial N can provide an electron-rich environment for Li^(+)transport layer and then reduce the Li^(+)diffusion barrier.Arising from the synergistic effect of N doping at different sites,the N-doped T-Nb_(2)O_(5) without carbon coating delivers impressive rate performance(104.6 mA h g^(-1) at 25 C)as well as enhanced cycle stability with a retention of 70.5%over1000 cycles at 5 C.In addition,the assembled lithium ion capacitor exhibits a high energy density of46.6 Wh kg^(-1) even at high power density of 8.4 kW kg^(-1).

Effects of the Different Supports on the Activity and Selectivity of Iron-Cobalt Bimetallic Catalyst for Fischer-Tropsch Synthesis

Silica, alumina, and activated carbon supported iron-cobalt catalysts were prepared by incipient wetness impregnation. These catalysts have been characterized by BET, X-ray diffraction （XRD）, and temperature-programmed reduction （TPR）. Activity and selectivity of iron-cobalt supported on different carriers for CO hydrogenation were studied under the conditions of 1.5 MPa, 493 K, 630 h^-1, and H2/CO ratio of 1.6. The results indicate that the activity, C4 olefin/（C4 olefin＋C4 paraffin） ratio, and C5 olefin/（C5 olefin＋C5 paraffin） decrease in the order of Fe-Co/SiO2, Fe-Co/AC1, Fe-Co/Al2O3 and Fe- Co/AC2. The activity of Fe-Co/SiO2 reached a maximum. The results of TPR show that the Fe-Co/SiO2 catalyst is to some extent different. XRD patterns show that the Fe-Co/SiO2 catalyst differs significantly from the others; it has two diffraction peaks. The active spinel phase is correlated with the supports.

The optional extent of lymph node dissection for pancreatic head cancer

Objective The extent of lymph node dissection for pancreatic head cancer(PHC)is uncertain and controversial;therefore,this study evaluated whether PHC patients can benefit from different extents of lymph node dissection.Methods A total of 106 PHC patients underwent standard regional lymphadenectomy(SRLN;n=56,52.8%)and extended regional lymphadenectomy(ERLN;n=50,47.2%)between September 2015 and September 2019.None of the study participants had distant metastases.The median survival time and complications were compared between the two groups.Results The median survival time in the SRLN and ERLN groups was 27.01 months and 21.17 months,respectively(P=0.30).The postoperative major morbidity and mortality rates were 37.50%and 1.79%in the SRLN group,and 46.00%and 2.00%in the ERLN group,respectively.Moreover,the tumor differentiation,tumor diameter,lymph node involvement,perineural invasion,vascular invasion,and margin status all correlated with survival(P<0.05).Conclusion For PHC patients,ERLN cannot provide a significant survival benefit over SRLN.Moreover,ERLN increased morbidity and mortality,although without statistical significance.This indicates that ERLN should not be considered in PHC patients.

微分散法连续制备微气泡的研究进展

微气泡的尺寸介于1~1000μm之间。相比于传统大气泡,微气泡具有体积小、比表面积大、上浮速度慢和传质效率高等优点,被广泛应用于石油、化工、食品、化妆品、医学和废水处理等领域。相比于传统的微气泡制备方法,气液微分散法制备微气泡生产效率高、可控性好、灵活性高和易于放大,受到了学者们的广泛关注。鉴于微气泡的广泛应用,快速准确的对气泡的大小和尺寸分布的表征也至关重要。本工作对常用的微气泡尺寸表征方法进行了归纳总结,比较了不同的微气泡制备方法的优缺点,并重点阐述了微通道法和膜分散法制备微气泡的研究现状。在此基础上对微分散法制备微气泡的未来研究方向进行展望。

Fabrication of flexible reduced graphene oxide/Fe2O3 hollow nanospheres based on-chip micro-supercapacitors for integrated photodetecting applications

Micro-supercapacitors （MSCs） as important on-chip micropower sources have attracted considerable attention because of their unique and advantageous design for optimized maximum functionality within a minimized sized chip and excellent mechanical flexibility/stability in miniaturized portable electronic device applications. In this work, we report a novel, high-performance flexible integrated on-chip MSC based on hybrid nanostructures of reduced graphene oxide/Fe2O3 hollow nanospheres using a microelectronic photo-lithography technology combined with plasma etching technique. The unique structural design for on-chip MSCs enables high-performance enhancements compared with graphene-only devices, exhibiting high specific capacitances of 11.57 F·cm^-3 at a scan rate of 200 mV·s^-1 and excellent rate capability and robust cycling stability with capacitance retention of 92.08% after 32,000 charge/discharge cycles. Moreover, the on-chip MSCs exhibit superior flexibility and outstanding stability even after repetition of charge/discharge cycles under different bending states. As-fabricated highly flexible on-chip MSCs can be easily integrated with CdS nanowire-based photodetectors to form a highly compacted photodetecting system, exhibiting comparable performance to devices driven by conventional external energy storage units.