高透明度和高强度的纳米粘合水凝胶贴片用于组织粘附

本研究旨在设计和制备一种具有优异机械性能和生物相容性的双层结构壳聚糖水凝胶粘合贴片,并借助纳米粘合策略评估其组织粘附性能。以物理交联构建坚韧的壳聚糖水凝胶作为背膜,随后通过原位光交联制备粘合剂水凝胶层,形成一体化的壳聚糖水凝胶粘合贴片。利用纳米胶水促进贴片与基底之间的纳米粘合。表面活化的二氧化硅纳米颗粒作为类似于纳米胶的界面连接器,促进水凝胶与基底的结合,以建立水凝胶贴片与生物组织之间的粘附关系。分析结果显示,水凝胶贴片在体外对生物组织的粘合能量为282 J/m^(2),爆破压力为450 mmHg(1 mmHg=0.133 kPa)。该贴片具有4.3 MPa的拉伸强度、65%的断裂伸长率和3.82 kJ/m^(2)的断裂韧性,具有出色的机械性能。此外,这种基于纳米粘合剂的壳聚糖水凝胶粘合贴片具有高透明度和优异的生物相容性,有望在组织修复和药物输送等多个生物医学领域得到应用,为临床外科手术的发展提供坚实的材料基础。

Finned Zn-MFI zeolite encapsulated noble metal nanoparticle catalysts for the oxidative dehydrogenation of propane with carbon dioxide

Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.

Balancing free and confined metallic Ni for an active and stable catalyst——A case study of CO methanation over Ni/Ni–Al2O3

We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) was prepared via the one-pot evaporation induced self-assembly method. By using the incipient impregnation method, different amounts of free Ni were loaded over Ni-OMA(Ni/NiOMA) at a fixed total NiO content of 15 wt%. Characterization results confirmed the formation of wellstructured Ni-OMA, and the ordered structure was still well preserved even after impregnating NiO at a content of as high as 12 wt%. The catalysts were evaluated for the CO methanation as a model reaction under varied conditions. Importantly, the activity and stability of Ni/Ni-OMA for the titled reaction were significantly regulated by simply changing the ratio of the confined to free Ni. Over the optimum catalyst of NiO(2 wt%)/NiO(13 wt%)-OMA, the high activity at a temperature of as low as 300 ℃ was achieved with the space-time yield of methane over 7.6 g gcat-1 h-1 while a long-term stability for a time-onstream of 400 h was confirmed without an observable deactivation under the conditions of 600 ℃ and an extremely high gas hourly space velocity of 120,000 mL g-1 h-1. The results were well explained as the integrated merits of the free Ni for a high dispersion and the confined Ni in OMA for the anti-sintering property.

Joule-heated carbonized melamine sponge for high-speed absorption of viscous oil spills

Introducing heating function to oil sorbents opens up a new pathway to the fast cleanup of viscous crude oil spills in situ.The oil sorption speed increases with the rise of the temperature,thus oil sorbents with high heating temperature are desirable.Besides,the oil sorbents also need to be produced environment-friendly.Here we present carbonized melamine-formaldehyde sponges(CMSs)that exhibited superior heating performance and the CMSs could be massively fabricated through a non-polluting pyrolysis process.The conductive CMSs could be heated over 300℃with a low applied voltage of 6.9 V and keep above 250℃for 30 min in the air without obvious damage.Such high heating performance enabled heating up the oil spills with a high rate of 2.65℃·s^(-1) and 14%improvement of oil sorption coefficient compared with the state-of-the-art value.We demonstrated that one joule-heated CMS could continuously and selectively collect viscous oil spills(9,010 mPa·s)690 times its own weight in one hour.The CMSs will be a highly competitive sorbent material for the fast remediation of future crude oil spills.