•Density functional theory and microkinetic modelling are used to quantitatively determine the activities of flat and stepped surfaces of both nickel and nickel carbide.•The coke formation ...probability is evaluated on each surface.•A deactivation scheme, which could be used to rationalise the activity and coke formation observed experimentally, is developed.
Dry reforming is a promising reaction to utilise the greenhouse gases CO2 and CH4. Nickel-based catalysts are the most popular catalysts for the reaction, and the coke formation on the catalysts is the main obstacle to the commercialisation of dry reforming. In this study, the whole reaction network of dry reformation on both flat and stepped nickel catalysts (Ni(111) and Ni(211)) as well as nickel carbide (flat: Ni3C(001); stepped: Ni3C(111)) is investigated using density functional theory calculations. The overall reaction energy profiles in the free energy landscape are obtained, and kinetic analyses are utilised to evaluate the activity of the four surfaces. By careful examination of our results, we find the following regarding the activity: (i) flat surfaces are more active than stepped surfaces for the dry reforming and (ii) metallic nickel catalysts are more active than those of nickel carbide, and therefore, the phase transformation from nickel to nickel carbide will reduce the activity. With respect to the coke formation, the following is found: (i) the coke formation probability can be measured by the rate ratio of CH oxidation pathway to C oxidation pathway (rCH/rC) and the barrier of CO dissociation, (ii) on Ni(111), the coke is unlikely to form, and (iii) the coke formations on the stepped surfaces of both nickel and nickel carbide can readily occur. A deactivation scheme, using which experimental results can be rationalised, is proposed.
Beijing, the capital of China, is a densely populated city with poor air quality. The impact of high pollutant concentrations, in particular of aerosol particles, on human health is of major concern. ...The present study uses aerosol optical depth (AOD) as proxy to estimate long-term PM2.5 and subsequently estimates the premature mortality due to PM2.5. We use the AOD from 2001 to 2012 from the Aerosol Robotic Network (AERONET) site in Beijing and the ground-based PM2.5 observations from the US embassy in Beijing from 2010 to 2011 to establish a relationship between PM2.5 and AOD. By including the atmospheric boundary layer height and relative humidity in the comparative analysis, the correlation (R2) increases from 0.28 to 0.62. We evaluate 12 years of PM2.5 data for the Beijing central area using an estimated linear relationship with AOD and calculate the yearly premature mortality by different diseases attributable to PM2.5. The estimated average total mortality due to PM2.5 is about 5100 individuals per year for the period 2001-2012 in the Beijing central area, and for the period 2010-2012 the per capita mortality for all ages due to PM2.5 is around 15 per 10 000 person-years, which underscores the urgent need for air pollution abatement.
Buildings consume nearly 40% of primary energy production globally. Certified green buildings substantially reduce energy consumption on a per square foot basis and they also focus on indoor ...environmental quality. However, the co-benefits to health through reductions in energy and concomitant reductions in air pollution have not been examined.We calculated year by year LEED (Leadership in Energy and Environmental Design) certification rates in six countries (the United States, China, India, Brazil, Germany, and Turkey) and then used data from the Green Building Information Gateway (GBIG) to estimate energy savings in each country each year. Of the green building rating schemes, LEED accounts for 32% of green-certified floor space and publically reports energy efficiency data. We employed Harvard's Co-BE Calculator to determine pollutant emissions reductions by country accounting for transient energy mixes and baseline energy use intensities. Co-BE applies the social cost of carbon and the social cost of atmospheric release to translate these reductions into health benefits. Based on modeled energy use, LEED-certified buildings saved $7.5B in energy costs and averted 33MT of CO
, 51 kt of SO
, 38 kt of NO
, and 10 kt of PM
from entering the atmosphere, which amounts to $5.8B (lower limit = $2.3B, upper limit = $9.1B) in climate and health co-benefits from 2000 to 2016 in the six countries investigated. The U.S. health benefits derive from avoiding an estimated 172-405 premature deaths, 171 hospital admissions, 11,000 asthma exacerbations, 54,000 respiratory symptoms, 21,000 lost days of work, and 16,000 lost days of school. Because the climate and health benefits are nearly equivalent to the energy savings for green buildings in the United States, and up to 10 times higher in developing countries, they provide an important and previously unquantified societal value. Future analyses should consider these co-benefits when weighing policy decisions around energy-efficient buildings.
Aim
To describe the levels of work engagement, and to analyse the reciprocal relationships between social support, empathy, resilience and work engagement among haemodialysis nurses in China.
...Background
Work engagement is a critical workplace health indicator. Previous studies have examined work engagement perceived by nurses working in diverse hospital wards, or a specialty area (emergency care or intensive care), no previous studies have highlighted work engagement and its affecting factors among haemodialysis nurses.
Methods
Participants in the cross‐sectional study were 345 haemodialysis nurses employed in 17 hospitals in Chengdu, China. Hierarchical regression analyses were carried out to analyse the relationships between social support, empathy, resilience and work engagement in haemodialysis nurses.
Results
Resilience was the strongest positive significant contributor to work engagement, followed by other support and perspective taking (cognitive empathy). Nurses with longer occupational tenure reported higher levels of work engagement. Male nurses also reported greater work engagement than female nurses.
Discussion
Influence of work engagement was explored by social support, empathy and resilience, reflecting the need of haemodialysis nurses to understand the significance of focusing on their personal and environmental factors.
Conclusions
Positive resilience, other support and cognitive empathy can result in increased work engagement.
Implications for nursing
Training programs, such as mindfulness meditation training and empathy skills training, are recommended for nursing managers to enhance resilience and empathic capacity in nurses.
Implications for nursing policy
Nursing policies should be developed to establish supportive work environments in clinical practice settings and to support the education and training of psychological resilience and empathic capacity in order to foster work engagement.
Ceramic materials for thermal barrier coatings Cao, X.Q.; Vassen, R.; Stoever, D.
Journal of the European Ceramic Society,
2004, 2004-1-00, 20040101, Letnik:
24, Številka:
1
Journal Article
Recenzirano
This paper summarizes the basic properties of ceramic materials for thermal barrier coatings. Ceramics, in contrast to metals, are often more resistant to oxidation, corrosion and wear, as well as ...being better thermal insulators. Except yttria stabilized zirconia, other materials such as lanthanum zirconate and rare earth oxides are also promising materials for thermal barrier coatings.
The effects of tool rotational speed and probe length on lap joint quality of friction stir welded 2-mm AZ31B-H24 magnesium alloy were investigated in terms of welding defects, microstructure and ...mechanical properties. Tensile shear load initially increases with increasing tool rotational speed but decreases with further increase. However, the tensile shear load always increases with increasing probe length. The highest shear strength is obtained using a set of welding parameters resulting in a downward hooking defect at the maximum stress location of the top sheet. Sound lap joints with low distortion, lack of cavity, minor kissing bond and preferable hooking defects, and high tensile shear strength were successfully obtained, indicating the great potential of friction stir welding technique for magnesium alloys.
Abiotic stresses have a detrimental impact on plant growth and productivity and are a major threat to sustainable crop production in rapidly changing environments. Proline, an important amino acid, ...plays an important role in maintaining the metabolism and growth of plants under abiotic stress conditions. Many insights indicate a positive relationship between proline accumulation and tolerance of plants to various abiotic stresses. Because of its metal chelator properties, it acts as a molecular chaperone, an antioxidative defence molecule that scavenges reactive oxygen species (ROS), as well as having signalling behaviour to activate specific gene functions that are crucial for plant recovery from stresses. It also acts as an osmoprotectant, a potential source to acquire nitrogen as well as carbon, and plays a significant role in the flowering and development of plants. Overproduction of proline in plant cells contributes to maintaining cellular homeostasis, water uptake, osmotic adjustment and redox balance to restore the cell structures and mitigate oxidative damage. Many reports reveal that transgenic plants, particularly those overexpressing genes tailored for proline accumulation, exhibit better adaptation to abiotic stresses. Therefore, this review aims to provide a comprehensive update on proline biosynthesis and accumulation in plants and its putative regulatory roles in mediating plant defence against abiotic stresses. Additionally, the current and future directions in research concerning manipulation of proline to induce gene functions that appear promising in genetics and genomics approaches to improve plant adaptive responses under changing climate conditions are also highlighted.
Proline has multifaceted functions to combat abiotic stress in plants.
Identification of α-cluster states analogous to the C 12 Hoyle state in heavier α-conjugate nuclei can provide tests of the existence of α condensates in nuclei. Such states are predicted for O 16 , ...Ne20 , Mg24 , Si28 , etc., at excitation energies slightly above the multi- α-particle decay threshold but have not yet been experimentally identified. The thick target inverse kinematics (TTIK) technique can be used to study the breakup of excited self-conjugate nuclei into many α particles. The reaction Ne20+α was studied using a Ne20 beam at 12 MeV/nucleon from the K150 cyclotron at Texas A&M University. The TTIK method was used to study both single α-particle emission and multiple α-particle decays. Events with α multiplicity up to four were analyzed. The analysis of the three α-particle emission data allowed the identification of the Hoyle state and other C 12 excited states decaying into three α particles. The results are shown and compared with other data available in the literature. Although the statistics for events with α-multiplicity four is low, the data show a structure at about 15.2 MeV that could indicate the existence in O 16 of a state analogous to the C 12 Hoyle state. Moreover, the reconstructed excitation energy of Mg24 for these events peaks at around 34 MeV, very close to the predicted excitation energy for an excited state analogous to the C 12 Hoyle state in Mg24 . The structure is further confirmed by the reanalysis of α-multiplicity-four events from a previous experiment performed at 9.7 MeV/nucleon with a similar, but lower granularity, experimental setup.
A bimetallic Pt–Re catalyst can facilitate the hydrogenation of
N-methylpyrrolidin-2-one to
N-methylpyrrolidine to high conversion at low temperature and pressure. Catalyst preparation, ...characterisation and kinetic analysis combined with DFT calculations have shown that the role of rhenium is to activate the carbonyl bond, whilst that of the platinum is as a hydrogenation catalyst, removing intermediates from the surface of the catalyst.
Display omitted
► Bimetallic Pt–Re catalysts facilitate hydrogenation of amides under mild conditions. ► Characterisation, kinetic analysis and DFT calculations show the role of each metal. ► Re activates the carbonyl bond, Pt hydrogenates intermediates, cleaning the catalyst.
Hydrogenation of tertiary amides, in particular,
N-methylpyrrolidin-2-one, can be efficiently facilitated by a TiO
2-supported bimetallic Pt/Re catalyst at low temperatures and pressures. Characterisation of the catalysts and kinetic tests have shown that the close interaction between the Re and Pt is crucial to the high activity observed. DFT calculations were used to examine a range of metal combinations and show that the role of the uncoordinated Re is to activate the C
O and that of the Pt is as a hydrogenation catalyst, removing intermediates from the catalyst surface. The rate enhancement observed on the TiO
2 support is thought to be due to the presence of oxygen vacancies allowing adsorption and weakening of the C
O bond.
The subfamily of the Lemnoideae belongs to a different order than other monocotyledonous species that have been sequenced and comprises aquatic plants that grow rapidly on the water surface. Here we ...select Spirodela polyrhiza for whole-genome sequencing. We show that Spirodela has a genome with no signs of recent retrotranspositions but signatures of two ancient whole-genome duplications, possibly 95 million years ago (mya), older than those in Arabidopsis and rice. Its genome has only 19,623 predicted protein-coding genes, which is 28% less than the dicotyledonous Arabidopsis thaliana and 50% less than monocotyledonous rice. We propose that at least in part, the neotenous reduction of these aquatic plants is based on readjusted copy numbers of promoters and repressors of the juvenile-to-adult transition. The Spirodela genome, along with its unique biology and physiology, will stimulate new insights into environmental adaptation, ecology, evolution and plant development, and will be instrumental for future bioenergy applications.
PDF
