抗冻高分子水凝胶的设计策略及应用进展

高分子水凝胶具有优异的生物相容性、延展性和变形能力,在诸多领域显示出巨大的应用前景。然而,在低温下水分子冻结,水凝胶会失去其优异的性能。近年来抗冻水凝胶材料受到广大研究者的青睐。文中主要综述了抗冻高分子水凝胶的设计策略与方法,重点介绍了3类抗冻水凝胶,即基于离子水合作用的抗冻水凝胶、基于氢键作用的抗冻水凝胶及基于离子水合与氢键协同作用的抗冻水凝胶,并阐述了抗冻水凝胶材料在软致动器、超级电容器/电池和传感器等领域的应用进展,最后讨论了抗冻水凝胶在未来发展中仍然需要解决的关键性问题和发展方向。

Activation of small molecules over praseodymium-doped ceria

Praseodymium can modify the properties of ceria (CeO2), changing the electronic structure, reducibility and catalytic behavior. Oxygen vacancies in the ceria-based samples can activate C–O and C–H bonds of small molecules such as CO2 and propane. Partially reduced Pr/CeO2-x can selectively activate C–H of propane, giving a propylene selectivity of ca. 75% at a propane conversion of 5% to 10%. Excess reduction of Pr/CeO2-x induces coking reactions during propane dehydrogenation, resulting in fast catalyst deactivation.

Tailoring the tribological properties of nanostructured carbon films under water lubrication

Carbon films have been considered suitable to be applied in water lubrication since they exhibit excellent friction-reducing and wear resistance,chemical inertness,etc.However,the basic understanding of tribological behaviors of carbon-based films under water lubrication still needs to be explored.In the present work,carbon films with different nanostructures were prepared by the electron cyclotron resonance(ECR)plasma nano-surface manufacturing system,and micro-textures with different sizes were prepared on the surface of carbon films by plasma etching.The influence of nanostructure and surface texture on the tribological properties of carbon films was investigated.The results show that different nanostructured carbon films can obtain lower friction coefficients and longer wear life under water lubrication than under dry condition.Due to low surface roughness,high hardness,and compact structure,the tribological properties of amorphous carbon(a-C)films under water lubrication are much better than those of graphene sheet-embedded carbon(GSEC)films.The prepared surface texture has a negative effect on the hard a-C film,but it can make the soft GSEC film generate soft wear debris at the initial stage.With the action of water,the soft wear debris is bonded on the surface of the contacting ball to form a silt-like transfer film,which increases the wear life by nearly three orders of magnitude.These results extend the basic understanding of the tribological behavior of carbon film under water lubrication,which is crucial in both fundamental and applied science.

Clinical outcomes of sildenafil application in patients of poor endometrial development

Objective:To determine whether sildenafil has an efect on pregnancy outcomes in patients with poor endometrial development.Mathods:This study included 472 infertility patients who underwent in viro fer tilization/intracytoplasmadc spemm injection and frozen-thawed embryo tr ansfer(IVF/ICSI-FET)and subsequently sufered from poor endo-metral dewelopment during homnone replacement cycle(HRC)from April 2017 to July 2019.The patients were divided into two groups:the sildenafl group(n=88)and the control group(n=384).We analyzed endometrial thicknuess and types on endometrial transformation day,as well as pregnancy outcomes after FET(biochemical pregnancy,clinical pregnancy,early abortion,late abortion,and live birth rates)between the two groups.Results:After adjusting for confounding factors,we found no significant differences in endometrial thicknesses and types on endometrial transfomation day between the sildenafil group and the control group(0.79±0.08 vs 0.81±0.09,P=0.144;79.76%vs83.87%,P=0.402).There were also no statistcally significant differences in biochemical pregnancy rate(75.0%vs76.8%,P=0.892),clinical pregnancy rate(59.09%vs 69.53%,P=0.087),early abortion rate(17.31%vs 14.61%,P=0.557),late abortion rate(3.85%vs 4.49%,P=0.859),or live birth rate(45.45%vs 55.47%,P=0.101)between the two groups.In subgroup analysis,the application of sildenafil was unable to improve endometrial thickness(group one:0.80±0.08 cm vs 0.82±0.08 cm;group two:0.78±0.08 cm vs 0.80±0.10 cm;group three:0.75±0.11 cm vs 0.77±0.08 cm,p>0.05)and type endometrium on transfomation day(group one:78.57%vs 86.78%;group two:80.65%vs 77.78%;group three:81.82%ws.83.78%,p>0.05).Moreover,sildenafil use was not closely associated with clinical pregnancy outcomes,clinical pregnancy rate,early abortion rate,late abortion rate,and live birth rate(p>0.05).Conclusions:Sildenafl did not benefit endometrial development and pregnancy outcomes in patients with poor endometr:ial development during the hormone replacement cycle.