Theoretical study of adsorption of organic phosphines on transition metal surfaces

<p>The adsorption properties of organic phosphines on transition metal (TM) surfaces (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au) have been studied to explore the possibility of building novel heterogeneous chiral catalytic systems based on organic phosphines. Preferred adsorption sites, adsorption energies and surface electronic structures of a selected set of typical organic phosphines adsorbed on TM surfaces are calculated with density-functional theory to obtain a systematic understanding on the nature of adsorption interactions. All organic phosphines considered are found to chemically adsorb on these TM surfaces with the atop site as the most preferred one, and the TM–P bond is formed via the lone-pair electrons of the P atom and the directly contacted TM atom. These findings imply that it is indeed possible to build heterogeneous chiral catalytic systems based on organic phosphines adsorbed on TM surfaces, which, however, requires a careful design of molecular structure of organic phosphines.</p

Migration of Phosphorus in Sewage Sludge during Different Thermal Treatment Processes

The utilization of phosphorus (P) in activated sludge discharged from wastewater treatment plants is an important part of the global phosphorus circulation. Thermal treatment of excess sludge would become a promising method for their disposal throughout the world. Herein, we investigated the transformation and migration of P in sewage sludge during different thermal treatment conditions. The results indicate that the temperature can significantly influence the species and content of P in the sewage sludge char or ash (SSC/A), while the atmosphere of thermal treatment has a slight effect on the fate of P. ³¹P NMR and XRD analysis indicated that P migrated mainly to the medium-term plant available P pool (pool_NaOH) on treating the sewage sludge at a low temperature (673–873 K), while it was prone to migration to the long-term plant available P pool (pool_HCl) when treated at a high temperature (873–1073 K)

Theoretical Investigation of Ta₂O₅, TaON, and Ta₃N₅: Electronic Band Structures and Absolute Band Edges

Early transition metal oxides, nitrides, and oxynitrides have attracted a great deal of interest because of their potential applications in photovoltaics and photocatalysis. In this work, a systematic investigation is conducted of the electronic band structures of the Ta₂O₅ polymorphs, β-Ta₃N₅ and β-TaON, which are crucial for the understanding of their photocatalytic properties, based on state-of-the-art first-principles approaches. The calculated results imply that many-body perturbation theory in the <i>GW</i> approximation can overcome the severe underestimation of the band gap caused by standard density functional theory (DFT) in the local and semilocal approximations and provide a quantitative agreement with experiment. The effects of the electron–phonon coupling on the electronic band structure are considered by the Frölich model, and especially for ϵ-Ta₂O₅, a strong electron–phonon coupling is predicted as a result of small high-frequency dielectric constants and large effective masses. Based on an analysis in terms of the phenomenological ionic model, the band-gap difference between three compounds can be physically attributed to not only the well-known energy difference between the O 2p and N 2p orbitals, but also the influences of the Madelung potential on the conduction-band energy. By comparing the calculated absolute band edge positions to the redox potentials for water reduction and oxidation, all three of the compounds are predicted to have potential photocatalytic properties for unassisted water splitting. In addition, we also analyzed the stability and band gaps of different Ta₂O₅ polymorphs and found that the β-Ta₂O₅, the phase commonly used in theoretical studies, is actually unstable and its unusually small band gap can be attributed to the strong overlap of neighboring atomic orbitals. On the other hand, ϵ-Ta₂O₅, which is much less well studied compared to β-Ta₂O₅, leads to calculated properties that are much more consistent with the experimental findings for Ta₂O₅ in general. The theoretical analysis and findings presented in this work have general implications for the understanding of the electronic band structures of other early transition metal compounds

Comparative Investigation on Photoreactivity and Mechanism of Biogenic and Chemosythetic Ag/C₃N₄ Composites under Visible Light Irradiation

A Ag/C₃N₄ nanocomposite with optimum Ag content is an efficient and green photocatalyst for pollutant degradation under visible light irradiation. In this study, we synthesized Ag NPs using NaBH₄ and the squeezed out liquid (SOL) of plant biomass. The Ag NPs thus obtained have been loaded to C₃N₄ to form Ag/C₃N₄ nanocomposites that show superior photocatalytic performance toward Rhodamine B (RhB) under visible light irradiation. The photocatalytic activity of both biogenic and chemogenic Ag/C₃N₄ nanocomposites with different Ag contents is compared. Results show that the biogenically synthesized Ag/C₃N₄ exhibits better photocatalytic performance than the chemosynthetic composite. Of all the different nanocomposites prepared in this study, Ag₄₈/C₃N₄ (0.048% of Ag content) exhibits excellent photoreactivity, with a reaction rate constant (<i>k</i>) 7-fold higher that the chemosynthetic Ag/C₃N₄. The observed improvement in the photoreactivity is mainly attributed to the high dispersion of Ag NPs on C₃N₄, facilitated by the organic compounds in SOLs. Besides, these organic compounds also enhance the photoreactivity of the catalyst by providing adsorption sited for RhB molecules and by shifting the Fermi level to more negative potential

Additional file 3: Figure S2. of Association between periodontal disease and mortality in people with CKD: a meta-analysis of cohort studies

Sensitivity analysis: Forest plot of risk of all-cause death limiting to studies with low risks of bias. (TIFF 252 kb

Robustness tests.

This paper theoretically analyzes and empirically examines the impact and mechanisms of automated machines on employment in manufacturing enterprises, drawing on task-based model and using micro data from listed Chinese manufacturing enterprises between 2012 and 2019. Our findings reveal that: (1) Automated machines in manufacturing enterprises leads to a substitution effect on the total labor force, with a substitution effect on low-skilled labor and a creation effect on high-skilled labor in terms of employment structure. (2) Further analysis indicates that automated machines primarily have a positive effect on R&D and technical staff, a non-significant effect on sales staff, and a negative impact on production, administrative, and financial staff. (3) The primary influencing mechanisms of automated machines on employment in manufacturing firms are productivity effects and output scale effects, based on the mediation effect model. (4) Considering the industry linkage effect, we employ the input-output method and the Input-Output Table and find that automated machines for upstream (downstream) manufacturing enterprises will result in a substitution effect on employment for downstream (upstream) enterprises. The novelties and research contributions are as follows: (1) we conduct a structural decomposition of total employment, and further decompose employment positions into production, R&D, sales, finance, and administration. (2) We try to investigate the industry linkage effect about the impact of automated machines on the employment of upstream and downstream enterprises. (3) We use data from listed manufacturing companies, and the data of existing research are about provincial and industry-level data.</div

Preventing the Release of Cu²⁺ and 4‑CP from Contaminated Sediments by Employing a Biochar Capping Treatment

Preventing release of refractory pollutants from contaminated sediments is of growing concern. In situ remediation of sediments becomes more popular because of its low cost and noninterference of benthic ecosystems compared with conventional sediment dredging. In this study, a low-cost rice husk biochar (RHB) was used as a capping material to prevent the release of representative inorganic (Cu²⁺) and organic (4-chlorophenol, 4-CP) pollutants from synthetic contaminated sediments. In addition, the release dynamics of pollutants was investigated under different environmentally relevant conditions. The experimental results indicated that RHB can efficiently suppress the release of Cu²⁺ and 4-chlorophenol from the sediments and a select thickness of RHB can maintain the concentrations of these model pollutants below the national criterion at pH = 5 and 7, even when the concentrations of these pollutants are very high (1600 mg kg^–1 of Cu²⁺ or 100 mg kg^–1 of 4-CP). Fitting the release data of pollutants to the zero order equation, the Elovich equation, the parabolic diffusion law, and the two-constant rate equation demonstrated that a simple model cannot precisely describe the complicated release kinetic process of the pollutants. This study demonstrated a facile remediation application of RHB and helped to provide the information needed for future risk assessments and policy-making

Results of industry linkage effects.

This paper theoretically analyzes and empirically examines the impact and mechanisms of automated machines on employment in manufacturing enterprises, drawing on task-based model and using micro data from listed Chinese manufacturing enterprises between 2012 and 2019. Our findings reveal that: (1) Automated machines in manufacturing enterprises leads to a substitution effect on the total labor force, with a substitution effect on low-skilled labor and a creation effect on high-skilled labor in terms of employment structure. (2) Further analysis indicates that automated machines primarily have a positive effect on R&D and technical staff, a non-significant effect on sales staff, and a negative impact on production, administrative, and financial staff. (3) The primary influencing mechanisms of automated machines on employment in manufacturing firms are productivity effects and output scale effects, based on the mediation effect model. (4) Considering the industry linkage effect, we employ the input-output method and the Input-Output Table and find that automated machines for upstream (downstream) manufacturing enterprises will result in a substitution effect on employment for downstream (upstream) enterprises. The novelties and research contributions are as follows: (1) we conduct a structural decomposition of total employment, and further decompose employment positions into production, R&D, sales, finance, and administration. (2) We try to investigate the industry linkage effect about the impact of automated machines on the employment of upstream and downstream enterprises. (3) We use data from listed manufacturing companies, and the data of existing research are about provincial and industry-level data.</div

Slow Pyrolysis Magnetization of Hydrochar for Effective and Highly Stable Removal of Tetracycline from Aqueous Solution

Although biochar has been intensively studied as an inexpensive adsorbent for diverse organic pollutants in aqueous solution, synchronously achieving high adsorption capacity, separability, and stability is still a challenge. Herein, we partially addressed this issue via an integrated activation and pyrolytic magnetization of sawdust hydrochar, during which the surface area of magnetic activated sawdust hydrochar (M-SDHA) increases from 1.7 to 1710 m² g^–1, and the weight loss decreases from 70 to 5% at 700 °C. Correspondingly, the maxmium adsorption capacity of M-SDHA toward tetracycline (TC) reaches 423.7 mg g^–1 and remains constant at pH 5–9. Multiple characterizations show that the fine pore structure and surface functional groups of M-SDHA were maintained during the pyrolysis magnetization process, which is responsible for the high adsorption capacity. In the pyrolysis magnetization process, the FeCl₃ was reduced to Fe₃O₄ which endowed M-SDHA with magnetism and may simultaneously improve the thermostability of M-SDHA. In addition, acidic–basic stability of M-SDHA may be responsible for the stable adsorption toward TC at different pHs based on Fourier transform infrared spectroscopic results. These results along with the column adsorption experiment show that M-SDHA is an effective and practical adsorbent for TC removal

Estimated coefficients and confidence intervals of column 2 in Table 3.

Estimated coefficients and confidence intervals of column 2 in Table 3.</p