We report the design and synthesis of nanosized Zn(x)Zr(y)O(z) mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (~83%). ZnO is addded to ZrO(2) to selectively passivate zirconia's strong Lewis acidic sites and weaken Brönsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brönsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized Zn(x)Zr(y)O(z) mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene.

Summary 1.The interactions between adjacent trophic levels are essential for ecosystem functioning and stability. Grazing by domestic herbivores is an essential interaction in grasslands, but little information is available on the nature of relationship between plant and insect diversity under grazing by large herbivores. 2. We examined the effects of large herbivores on the relationship between plant and insect diversity with five grazing treatments (control, cattle, goat, sheep and a mixture of the three grazing types) across three plant diversity levels (low: 4-5 species, intermediate: 8-9 species and high: 15-17 species) in a meadow steppe. 3. We found that the grazing treatments did not significantly affect plant species richness, but reduced plant biomass, plant height and cover. Grazers affected variation in plant height differently at different plant diversity levels, and this variation increased at the low plant diversity level and decreased at the high plant diversity level after grazing. A similar pattern was observed for insect species richness: grazing had a positive impact at the low plant diversity level, but had a negative impact at the high plant diversity level. 4. In the absence of grazing, insect species richness was positively associated with plant species richness, but it decreased with increasing plant diversity in the grazing treatments. This was attributed to strong responses of insect species richness to plant height heterogeneity under grazing by large herbivores, implying that plant structural heterogeneity is more important than plant diversity in influencing insect diversity in grazed grasslands. 5. Synthesis and applications. Grazing by large herbivores may reverse the positive relationship between plant diversity and insect diversity by modifying plant structural heterogeneity. Therefore, the spatial heterogeneity of vegetation structure should be given more attention in future work on plant-insect interactions. This study further highlights the importance of using large herbivore grazing in management actions, not only to maintain diversity but also to mediate trophic interactions in grasslands.

The visbreaking of heavy oil under high-pressure N2 or supercritical water (SCW) environment was experimentally investigated. Despite the difference in the reaction media, the visbreaking follows the same mechanism, that is, dealkylation and condensation of aromatics. The presence of SCW makes it possible that the visbreaking of heavy oil is transferred to the SCW phase with superior diffusivity by which the visbreaking tends to be controlled by intrinsic reaction kinetics rather than by diffusion. Accordingly, dealkylation occurring in the SCW phase, which is vital to the viscosity reduction of heavy oil, responds sensitively to the increase in reaction temperature. Being the secondary reaction of dealkylation at moderate temperatures, condensation is effectively suppressed with reduced reaction time required for dealkylation. By the introduction of SCW and the adoption of an appropriate reaction temperature, the visbreaking efficiency could be drastically improved together with guaranteed stability of visbreaking products.

BackgroundThis retrospective analysis compared the long-term outcomes for patients with a femoral neck fracture (AO/OTA type 31B) treated with a primary unilateral total hip arthroplasty with uncemented or cemented femoral components (UTHA or CTHA, respectively).MethodsWe conducted a retrospective cohort study using the South China Hip Arthroplasty Database. We identified 422 patients with femoral neck fracture (AO/OTA type 31B) who were previously treated with primary unilateral UTHA or CTHA between 2007 and 2015, with follow-up until 2019. Follow-up occurred 1, 3, 6 and 12 months postoperatively and yearly thereafter. The primary outcome was the Harris hip score (HHS). The secondary outcome was the orthopaedic complication rate.ResultsIn total, 324 patients (UTHA n = 160, mean age 68.61 ± 7.49 years; CTHA n = 164, mean age 68.75 ± 7.04 years) were evaluated for study eligibility. The median follow-up was 73.3 months (range, 11.6–89.2 months). At the final follow-up, HHS was 74.09 ± 6.23 vs 79.01 ± 10.21 (UTHA vs CTHA, p = 0.012). Significant differences were detected in the incidence of prosthetic revision, loosening, and periprosthetic fracture between the UTHA and CTHA groups (7.5% for UTHA vs 1.8% for CTHA, p = 0.015; 17.5% for UTHA vs 8.5% for CTHA, p = 0.016; 11.9% for UTHA vs 4.9% for CTHA, p = 0.021, respectively).ConclusionIn this setting, CTHA demonstrated superiority to UTHA by improving functional outcomes and decreasing complication rates.