Study on the development process of apron controller's work fatigue based on heart rate characteristics.

In order to study the fatigue development and change pattern of apron controllers in the process of each work, experiments were carried out at Beijing Daxing International Airport, and the physiological data of personnel were collected by smart band senselessly. The incremental relationship between heart rate characteristics and personnel reaction time before and after work was compared and analyzed; the change in duty time, workload and heart rate of controllers were studied quantitatively, and the regulatory role of the body and fatigue changes were analyzed, then the pattern of heart rate changes with fatigue development was found. The results of the study showed that the heart rate characteristics were related to the workload of the controllers, correlated with the change pattern of personnel reaction time characteristics. The p-values are less than 0.05. So the fatigue state of personnel could be objectively characterized by heart rate. The heart rate of apron controllers showed a jittering decreasing trend during 3 h of work, and its distribution showed obvious banded dense areas. The relative heart rate gradually decreases from 0.6 to about 0.2. The 95% confidence intervals for time of the occurrence of minimal values of heart rate during the first 2 h and the last 1 h of work time were statistically estimated as [57.38,81.42] and [143.79,155.45] respectively, and further calculated the corresponding confidence intervals for number of flights, which are the possible fatigue severity intervals. The study can provide valuable references for controller shift management and personnel status monitoring timing during daily work.

Cu Species-Modified OMS-2 Materials for Enhancing Ozone Catalytic Decomposition under Humid Conditions.

Manganese oxide octahedral molecular sieves (OMS-2) exhibit an excellent performance in ozone catalytic decomposition in dry atmosphere conditions, which however is severely limited by deactivation in humid conditions. Herein, it was found that the OMS-2 materials modified with Cu species could obviously improve both the ozone decomposition activity and water resistance. Based on the characterization results, it was found that these CuOx/OMS-2 catalysts exhibited dispersed CuOx nanosheets attached and located at the external surface accompanied with ionic Cu species entering the MnO6 octahedral framework of OMS-2. In addition, it was demonstrated that the main reason for the promotion of ozone catalytic decomposition could be ascribed to the combined effect of different Cu species in these catalysts. On the one hand, ionic Cu entered the MnO6 octahedral framework of OMS-2 near the catalyst surface and substituted ionic Mn species, resulting in an enhanced mobility of surface oxygen species and formation of more oxygen vacancies, which act as the active sites for ozone decomposition. On the other hand, the CuOx nanosheets could serve as non-oxygen vacancy sites for H2O adsorption, which could alleviate the catalyst deactivation to some extent caused by the occupancy of H2O on surface oxygen vacancies. Finally, different reaction pathways for ozone catalytic decomposition over OMS-2 and CuOx/OMS-2 under humid conditions were proposed. The findings in this work may shed new light on the design of highly efficient catalysts for ozone decomposition with improved water resistance.

Unveiling the Surface Structure of ZnO Nanorods and H2 Activation Mechanisms with 17O NMR Spectroscopy.

ZnO plays a very important role in many catalytic processes involving H2, yet the details on their interactions and H2 activation mechanism are still missing, owing to the lack of a characterization method that provides resolution at the atomic scale and follows the fate of oxide surface species. Here, we apply 17O solid-state NMR spectroscopy in combination with DFT calculations to unravel the surface structure of ZnO nanorods and explore the H2 activation process. We show that six different types of oxygen ions in the surface and subsurface of ZnO can be distinguished. H2 undergoes heterolytic dissociation on three-coordinated surface zinc and oxygen ions, while the formed hydride species migrate to nearby oxygen species, generating a second hydroxyl site. When oxygen vacancies are present, homolytic dissociation of H2 occurs and zinc hydride species form from the vacancies. Reaction mechanisms on oxide surfaces can be explored in a similar manner.

The active sites of Cu-ZnO catalysts for water gas shift and CO hydrogenation reactions.

Cu-ZnO-Al2O3 catalysts are used as the industrial catalysts for water gas shift (WGS) and CO hydrogenation to methanol reactions. Herein, via a comprehensive experimental and theoretical calculation study of a series of ZnO/Cu nanocrystals inverse catalysts with well-defined Cu structures, we report that the ZnO-Cu catalysts undergo Cu structure-dependent and reaction-sensitive in situ restructuring during WGS and CO hydrogenation reactions under typical reaction conditions, forming the active sites of CuCu(100)-hydroxylated ZnO ensemble and CuCu(611)Zn alloy, respectively. These results provide insights into the active sites of Cu-ZnO catalysts for the WGS and CO hydrogenation reactions and reveal the Cu structural effects, and offer the feasible guideline for optimizing the structures of Cu-ZnO-Al2O3 catalysts.

Structure Sensitivity of Au-TiO2 Strong Metal-Support Interactions.

Strong metal-support interactions (SMSI) is an important concept in heterogeneous catalysis. Herein, we demonstrate that the Au-TiO2 SMSI of Au/TiO2 catalysts sensitively depends on both Au nanoparticle (NP) sizes and TiO2 facets. Au NPs of ca. 5 nm are more facile undergo Au-TiO2 SMSI than those of ca. 2 nm, while TiO2 {001} and {100} facets are more facile than TiO2 {101} facets. The resulting capsulating TiO2-x overlayers on Au NPs exhibit an average oxidation state between +3 and +4 and a Au-to-TiO2-x charge transfer, which, combined with calculations, determines the Ti:O ratio as ca. 6:11. Both TiO2-x overlayers and TiO2-x -Au interface exhibit easier lattice oxygen activation and higher intrinsic activity in catalyzing low-temperature CO oxidation than the starting Au-TiO2 interface. These results advance fundamental understanding of SMSI and demonstrate engineering of metal NP size and oxide facet as an effective strategy to tune the SMSI for efficient catalysis.

Interaction of Hydrogen with Ceria: Hydroxylation, Reduction, and Hydride Formation on the Surface and in the Bulk.

The study reports the first attempt to address the interplay between surface and bulk in hydride formation in ceria (CeO2 ) by combining experiment, using surface sensitive and bulk sensitive spectroscopic techniques on the two sample systems, i.e., CeO2 (111) thin films and CeO2 powders, and theoretical calculations of CeO2 (111) surfaces with oxygen vacancies (Ov ) at the surface and in the bulk. We show that, on a stoichiometric CeO2 (111) surface, H2 dissociates and forms surface hydroxyls (OH). On the pre-reduced CeO2-x samples, both films and powders, hydroxyls and hydrides (Ce-H) are formed on the surface as well as in the bulk, accompanied by the Ce3+ ↔ Ce4+ redox reaction. As the Ov concentration increases, hydroxyl is destabilized and hydride becomes more stable. Surface hydroxyl is more stable than bulk hydroxyl, whereas bulk hydride is more stable than surface hydride. The surface hydride formation is the kinetically favorable process at relatively low temperatures, and the resulting surface hydride may diffuse into the bulk region and be stabilized therein. At higher temperatures, surface hydroxyls can react to produce water and create additional oxygen vacancies, increasing its concentration, which controls the H2 /CeO2 interaction. The results demonstrate a large diversity of reaction pathways, which have to be taken into account for better understanding of reactivity of ceria-based catalysts in a hydrogen-rich atmosphere.

Oxidation of Reduced Ceria by Incorporation of Hydrogen.

The interaction of hydrogen with reduced ceria (CeO2-x ) powders and CeO2-x (111) thin films was studied using several characterization techniques including TEM, XRD, LEED, XPS, RPES, EELS, ESR, and TDS. The results clearly indicate that both in reduced ceria powders as well as in reduced single crystal ceria films hydrogen may form hydroxyls at the surface and hydride species below the surface. The formation of hydrides is clearly linked to the presence of oxygen vacancies and is accompanied by the transfer of an electron from a Ce3+ species to hydrogen, which results in the formation of Ce4+ , and thus in oxidation of ceria.

In situ real-time diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) study of hydrogen adsorption and desorption on Ir/SiO2 catalyst.

The adsorption and desorption of hydrogen on Ir/SiO(2) catalyst were studied by using in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) combined with curve-fitting analysis. The results indicate that there are three different surface species formed on the catalyst that correspond to the peaks at 1950, 2010, and 2035 cm(-1), respectively, when exposed in H(2) flow at 130 °C. These surface species display different adsorption and desorption trends. Surface hydride forms after the catalyst is cooled to 80 °C and it disappears after the catalyst is heated to 130 °C again. This study may help us understand the interaction between hydrogen and noble metals and thus give more insights to heterogeneous catalytic mechanism involving hydrogen and hydrogen storage using metal materials.

Triaqua-(7-oxabicyclo-[2.2.1]heptane-2,3-dicarboxyl-ato-κO,O,O)cobalt(II) monohydrate.

The title complex, [Co(C(8)H(8)O(5))(H(2)O)(3)]·H(2)O, was synthesized by reaction of cobalt acetate with 7-oxabicyclo-[2.2.1]heptane-2,3-dicarb-oxy-lic anhydride (norcantharidin) in aqueous solution. In the mol-ecule, the Co(II) atom is six-coordinated in a distorted octa-hedral environment, binding to the bridging O atom of the bicyclo-heptane unit, to two O atoms from monodentate carboxyl-ate groups and to three water O atoms. The crystal structure is stabilized by several O-H⋯O hydrogen-bonding inter-actions involving both the coordinated and uncoordinated water mol-ecules as donors and the carboxyl-ate O atoms of neighbouring mol-ecules as acceptors.

Immobilization of Prussian Blue nanoparticles onto thiol SAM modified Au electrodes for electroanalytical or biosensor applications.

Poly(vinylpyrrolidone) (PVP)-protected Prussian Blue (PB) nanoparticles were prepared by simply mixing FeCI3 and K4Fe(CN)6 with absence or presence of HCI or/and KCI in water solution. The obtained PB nanoparticles were immobilized onto thiol self-assembled monolayer (SAM) modified Au electrodes. L-cysteine (Cys) and 1,8-octanedithiol (ODT) were compared as a bridge between the gold surface and the PB nanoparticles. The results show that PB prepared from the initial solution with KCI gives preferred electrochemical response and that Cys/Au shows improved immobilization effect of PB than ODT/Au. The obtained PB/Cys/Au electrodes exhibit electrocatalytic activity toward H2O2 reduction and DL-homocysteine (HCys) oxidation. Glucose oxidase (GOX) was immobilized onto PB modified electrode to explore the potentials for the design of oxidase-based biosensors. It is possible to anchor PB nanoparticles and develop their application on electroanalysis and biosensing.

[Mitigation effect of several controlled-release N fertilizers on ammonia volatilization and related affecting factors].

By using static absorption and soil column leaching methods, this paper studied the behaviors of several controlled-release N fertilizers in soil under laboratory conditions. The results showed that under the application rate of 450 mg x kg(-1), total ammonia volatilization from three controlled-release fertilizers decreased by 49.7%, 28.0% and 71.2%, respectively, in comparing with common urea. When the application rate was 600 mg x kg(-1), total ammonia volatilization decreased by 34.6%, 12.3%, 69.9%, respectively. Controlled-release fertilizers could markedly reduce total ammonia volatilization from soil and decrease environment pollution via fertilization. The results also indicated that total ammonia volatilization correlated significantly with soil urease activity, pH value and N leaching rate. The correlation coefficient between total ammonia volatilization and accumulated N leaching rate was 0.9533, and that between total ammonia volatilization and soil urease activity and pH value was 0.9533 and 0.9908, respectively.