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Ammonia synthesis remains one of the most important catalytic processes since it enables efficient hydrogen storage and provides the basis for the production of fertilizers. Herein, complementary bulk and local analytical techniques were combined to investigate the effect of selected promoters (Al, K, Ca) on the reduction of wuestite into α-iron and their catalytic performance for ammonia synthesis. The use of promoters appears to have a positive effect on the wuestite-derived catalyst in ammonia synthesis. The promoters seemingly act as a binder for wuestite grains and impede the reduction and disproportionation events of wuestite precursors resulting in an increased catalytic performance. This effect is associated with an increase of surface area and mesoporosity. The study delivers new insights into the interplay of structure and promoters in wuestite-based catalysts.

The influence of oxygen poisoning on a state-of-the-art multipromoted iron-based industrial catalyst for ammonia synthesis as well as the effectivity of different gas purification methods to prevent oxygen poisoning for experiments on laboratory scale were studied in detail. Additionally, the observed results were compared to a common oxygen poisoning test from literature, which on the one hand confirmed its usability in a wide range of conditions, but on the other hand also demonstrated the limitations of this test.

Aim. Traditional sedation management consists of doctors adjusting the dosage of sedative drugs or adding other drugs in combination according to the evaluation of nurses; the nurses then execute the orders. The nurses’ passive execution in the process is not the ideal model for continuous evaluation and observation of sedation. This study aims to investigate the application and effects of nurse-provided procedural sedation and analgesia for patients in intensive care unit. Methods. The experimental group consisted of 354 heart surgery patients who received procedural sedation and analgesia from nurses from November 2020 to August 2021. The control group consisted of 301 patients who had had heart surgery and received the traditional sedation management program from January to October 2020. The differences in levels of the sedative effect, delirium, and unplanned extubation of patients between these two groups were compared. Results. There were no significant differences in baseline characteristics between the two groups ( P > 0.05 ). It was found that both insufficient sedation and excessive sedation decreased in the experimental group when compared to the control group, while the appropriate proportion of sedation increased (72.41% versus 37.98%); the difference was statistically significant ( P < 0.05 ). The incidence of delirium was lower for patients in the experimental group than for patients in the control group (37.01% versus 66.45%); the difference was statistically significant ( P < 0.05 ). The incidence of unplanned extubation caused by patient factors was lower for the experimental group than for the control group, but the difference was not statistically significant ( P > 0.05 ). Conclusion. The programmed sedation scheme led by nurses can improve the sedation effect and reduce the incidence of delirium. Implications for Practice. The management team gives the sedative goal and establishes the standard flowchart. The sedation management led by the nurse according to the goal and flowchart is better than the traditional sedation management.

Co-precipitated ZnO/Cr2O3 catalyst precursors were thermally pretreated in synthetic air (calcination), N2 (pyrolysis) and 10% H2 diluted in N2 (reduction) at temperatures in the range from 320 °C to 600 °C and then applied in methanol synthesis from CO and H2 at 260–300 °C and 60 bar. The X-ray diffraction patterns showed that increasing temperatures used in the thermal pretreatment lead to sintering of both the resulting non-stoichiometric Zn-Cr spinel and ZnO phases. However, reduced and pyrolyzed catalysts exhibit a much slower increase in particle size of the Zn-Cr spinel phase compared with the calcined catalyst. Correspondingly, at the same temperature of thermal pretreatment the specific surface areas of the catalyst follow the trend reduced catalyst > pyrolyzed catalyst > calcined catalyst. Chromate species were found to be present in the calcined catalyst, while their amount decreased with increasing calcination temperature. Infrared spectroscopy and temperature-programmed reduction confirmed the existence of carbonate species in the catalysts reduced or pyrolyzed below 500 °C. NH3 temperature-programmed desorption showed that the calcined catalysts exhibit more acid sites due to the existence of chromate species. The reduced and pyrolyzed catalysts demonstrate significantly improved performance in high-temperature methanol synthesis compared with the calcined catalysts, and the maximum methanol productivity was achieved subsequent to reduction at 500 °C. It is suggested that the thermal pretreatment in reducing or inert atmosphere favors the formation of oxygen vacancies, which are considered to be the active sites for the hydrogenation of CO.

In this work, composites with different amounts of graphene oxide (GO) and the copper-based metal–organic frameworks (HKUST-1) were synthesized. They have been applied in chemiluminescence (CL) as catalysts using the luminol–H2O2 system as a CL model for the first time. The results showed that the well-dispersed GO@HKUST-1 (GMs) greatly improved the CL intensity of the luminol–H2O2 system, up to 359-fold. Based on ascorbic acid (AA) inhibiting the CL of the luminol–H2O2–GMs system, a flow injection CL method for monitoring AA was developed. Under the optimized conditions, a good linear relationship was obtained from 0.001 μM to 10 μM, and the detection limit was 0.35 nM. Moreover, the method was successfully used to detect AA in commercial food and fruit juices with satisfactory results. Due to their fascinating features, the GMs would offer a suitable catalytic platform for CL systems and provide potential promise for the construction of CL sensors.

In this paper, a simple one-pot hydrothermal procedure to create three-dimensional (3D) graphene/multiwalled carbon nanotubes/Pd (G/MWCNTs/Pd) composite hydrogels with a unique porous nanostructure was reported. During the formation of the G/MWCNTs/Pd composites, 2D graphene sheets and 1D MWCNTs were self-assembled to form interconnected porous microstructures and ultrafine Pd NPs were in situ grown on the 3D carbon-based skeleton simultaneously. In the as-obtained nanocomposites, MWCNTs not only prevented the close restacking of graphene sheets to increase the specific surface area but also provided an additional transport path to the catalyst surfaces which facilitated reactant transport. The G/MWCNTs/Pd composites proved to be an efficient, recyclable, and robust catalyst for the Suzuki cross-coupling reactions under mild aerobic conditions, which was attributed to the 3D macroporous framework with high specific surface area, numerous activation sites, and efficient transport pathways for improving the catalytic performance. Moreover, catalyst separation could be easily achieved by simple filtration, and the catalyst could be reused for at least six runs without significant loss in catalytic activity. Additionally, nearly no Pd species was released from the G/MWCNTs/Pd composites during the catalytic reactions, showing the heterogeneity in the present catalysis system.

A series of ZnO/Cr2O3 catalysts with different Zn:Cr ratios was prepared by coprecipitation at a constant pH of 7 and applied in methanol synthesis at 260–300 °C and 60 bar. The X-ray diffraction (XRD) results showed that the calcined catalysts with ratios from 65:35 to 55:45 consist of ZnCr2O4 spinel with a low degree of crystallinity. For catalysts with Zn:Cr ratios smaller than 1, the formation of chromates was observed in agreement with temperature-programmed reduction results. Raman and XRD results did not provide evidence for the presence of segregated ZnO, indicating the existence of Zn-rich nonstoichiometric Zn–Cr spinel in the calcined catalyst. The catalyst with Zn:Cr = 65:35 exhibits the best performance in methanol synthesis. The Zn:Cr ratio of this catalyst corresponds to that of the Zn4Cr2(OH)12CO3 precursor with hydrotalcite-like structure obtained by coprecipitation, which is converted during calcination into a nonstoichiometric Zn–Cr spinel with an optimum amount of oxygen vacancies resulting in high activity in methanol synthesis. Density functional theory calculations are used to examine the formation of oxygen vacancies and to measure the reducibility of the methanol synthesis catalysts. Doping Cr into bulk and the (10–10) surface of ZnO does not enhance the reducibility of ZnO, confirming that Cr:ZnO cannot be the active phase. The (100) surface of the ZnCr2O4 spinel has a favorable oxygen vacancy formation energy of 1.58 eV. Doping this surface with excess Zn charge-balanced by oxygen vacancies to give a 60% Zn content yields a catalyst composed of an amorphous ZnO layer supported on the spinel with high reducibility, confirming this as the active phase for the methanol synthesis catalyst.

[1] Soil thickness acts as an important control for headwater hydrologic processes. Yet, its spatial distribution remains one of the least understood in catchment hydrology. Analytic methods are desirable to provide a simple way for predicting soil thickness distribution over a hillslope or a catchment. In this paper, a simple geomorphic-based analytical model is derived from the dynamic equations of soil thickness evolution in areas with no tectonic uplift or lowering since the recent geological past. The model employs terrain attributes (slope gradient, curvature, and upstream contributing area) as inputs on grid-based DEMs for predicting soil thickness evolution over time. The analytic model is validated first on nine abstract hillslopes through comparing 10 kyr simulation results between our proposed model and the numerical solution. The model is then applied to predict soil thickness evolution over 13 kyr in the 7.9 ha Shale Hills catchment (one of the Critical Zone Observatories in the U.S. located in central Pennsylvania). Field observed and model predicted values of soil thickness are in good agreement (with a root mean squared error of 0.39 m, R2 = 0.74, and absolute errors

A series of Co-modified Cu/ZnO/Al2O3 methanol synthesis catalysts with different Na loadings was prepared and applied in higher alcohol synthesis (HAS) at 280 °C, 60 bar and a ratio of H2/CO = 1. The bulk and surface properties of the catalysts were characterized after reduction and after 40 h time on stream (TOS) without exposing the catalysts to air during the transfer and the measurements. Increased presence of metallic Co0 after reduction at 350 °C was confirmed by X-ray photoelectron spectroscopy indicating metallic Cu0 to act as a reduction promoter. Catalysts with low Na loadings (⩽0.6 wt%) showed strong initial deactivation presumably due to coking of isolated Co0 surface sites favoring hydrocarbon formation. The selectivity to higher alcohols gradually increased during the first 10 h TOS indicating enhanced Cu–Co surface alloy formation considered as active sites for HAS. In contrast, with high Na loadings (⩾0.8 wt%) deactivation did not occur and stable performance with constant CO conversion and product distribution was observed indicating significantly altered structural properties. High Na loadings caused the stabilizing amorphous oxide matrix to collapse resulting in strong sintering of the metallic Cu particles, and an increased carbidization of metallic Co0 forming bulk Co2C was observed by X-ray diffraction. Close contact between metallic Co0 and Co2C, which is known to facilitate molecular CO adsorption, is assumed to generate additional active sites for HAS.

The self-assembled three-dimensional graphene nanohybrids with in situ-formed Fe3O4 and Pd nanoparticles on it (3DRGO_Fe3O4-Pd) are first synthesized by the one-pot solvothermal method, which have intrinsic peroxidase-like and oxidase-like activity. The catalytic mechanism is analyzed by the electron spin resonance (ESR), fluorescence, and electrochemical methods. The mimic enzyme catalytic activity of 3DRGO_Fe3O4-Pd is much higher than those of monometallic loaded nanohybrids and their physical mixture, probably caused by synergistic effect between Pd and Fe3O4 nanoparticles. The 3DRGO_Fe3O4-Pd nanohybrids was reproducible, stable, and reusable. After 10 cycles, the catalytic activity was still higher than 90%, and the morphology and structure were basically unchanged. Based on its high peroxidase-like activity, especially the enhanced affinity toward H2O2, a new colorimetric detection method for reduced glutathione (GSH) and glucose has been designed using H2O2 as an intermediary, which provides a simple, sensitive, and selective way to detect urine glucose of diabetes with a wide linear range and low detection limit.

Cu–Co-based catalysts were synthesized by co-precipitation using Cu, Co, Zn and Al nitrates and applied in higher alcohol synthesis (HAS) at 280 °C, 60 bar and a ratio of H2/CO = 1. The catalyst exhibiting a Cu/Co ratio of 2.5 was found to provide the best trade-off between product distribution and degree of CO conversion. After activation and 40 h time on stream reaching steady-state conditions the bulk and surface properties of the catalyst were thoroughly investigated without exposing it to air during the transfer and the measurements. The conditions during activation and HAS led to a significant enrichment of Zn in the surface composition of the catalysts. The XRD pattern of the catalyst after reaction compared with the reduced catalyst revealed further sintering of the metallic Cu nanoparticles and the growth of crystalline ZnO nanoparticles, but there were no indications for the presence of bulk metallic Co or for bulk alloying. With increasing time on stream the product distribution shifted favorably towards higher alcohols presumably due to an increased intimate interface contact between the large metallic Cu0 particles detected by XRD and the X-ray amorphous metallic Co surface species probed by XPS.