scholarly journals Preparation of a Novel Clay Loaded With Fe (VI) for Degradation of Cefazolin: Performance, Pathway and Mechanism

2021 ◽  
Author(s):  
Mingluo Zhou ◽  
Riyu Zhou ◽  
Peng Jiang ◽  
Huili Liang ◽  
Yi Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Ph Value ◽  
Degradation Mechanism ◽  
Synthesis Method ◽  
Optimization Method ◽  
Decomposition Reaction ◽  
Potassium Ferrate ◽  
Response Surface Optimization ◽  
The Density Functional Theory ◽  
Spectroscopic Characteristics

Abstract Cephalosporin antibiotics, a group of widely prescribed antibiotics, are frequently detected in wastewater effluent and in the natural aquatic environment. Materials have been sought to effectively degrade the antibiotics. In this study, a novel high-iron clay was prepared with potassium ferrate and montmorillonite via a strong alkaline in-situ synthesis method. Degradation of cefazolin sodium (CFZ) by this novel Fe (VI)-clay was investigated. The optimal conditions for the degradation of CFZ were determined using a single factor experiment and response surface optimization method. We found that 89.84 % removal efficiency was obtained in 137 min when pH value was 5.16 and Fe (VI)-clay dosage was 0.79 g/100mL. The CFZ degradation mechanism was studied by the Density Functional Theory (DFT) in combination with spectroscopic and mass spectroscopic analysis. The spectroscopic characteristics of the products at different stages showed that the oxidation decomposition reaction occurred during the degradation of CFZ by Fe(VI) -clay. Further, DFT calculation combined with GC-MS results showed that the degradation pathways of CFZ by the Fe (VI)-clay was mainly the cleavage of β-lactam, thiadiazole, tetrazole and dihydrothiazine rings.

scholarly journals On how the mechanochemical and co-precipitation synthesis method changes the sensitivity and operating range of the Ba2Mg1-xEuxWO6 optical thermometer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Quan T. H. Vu ◽  
Bartosz Bondzior ◽  
Dagmara Stefańska ◽  
Natalia Miniajluk-Gaweł ◽  
Maciej J. Winiarski ◽  
...  
Keyword(s):  
Density Functional ◽  
Synthesis Method ◽  
Double Perovskite ◽  
Relative Sensitivity ◽  
The Novel ◽  
Temperature Detection ◽  
The Density Functional Theory ◽  
Precision Temperature ◽  
Optical Thermometer ◽  
Co Precipitation

AbstractThe suitability of Ba2MgWO6 (BMW) double perovskite doped with Eu3+ for the construction of an optical thermometer was tested. It has been shown that by controlling the conditions of BMW synthesis, the sensitivity of the optical thermometer and the useful range of its work can be changed. Pure BMW and doped with Eu3+ samples were prepared using the mechano-chemical and co-precipitation methods. Both the absolute sensitivity and the relative sensitivity in relation to the synthesis route were estimated. The findings proved that the relative sensitivity can be modulated from 1.17%K−1 at 248 K, to 1.5%K−1 at 120 K for the co-precipitation and the mechanochemical samples, respectively. These spectacular results confirm the applicability of the Ba2MgWO6: Eu3+ for the novel luminescent sensors in high-precision temperature detection devices. The density-functional theory was applied to elucidate the origin of the host emission.

scholarly journals Structural characterization of kaempferol: a spectroscopic and computational study

2019 ◽  
Vol 38 (1) ◽  
pp. 49 ◽  
Author(s):  
Dejan Milenković ◽  
Jasmina M Dimitrić Marković ◽  
Dušan Dimić ◽  
Svetlana Jeremić ◽  
Dragan Amić ◽  
...  
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Chemical Shifts ◽  
Absolute Error ◽  
Nbo Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spectroscopic Characteristics

Calculations based on the density functional theory, with the B3LYP functional and the 6-311++G(d,p) basis set, were performed with the aim of confirming the molecular structure and spectroscopic characteristics of kaempferol, a naturally occurring flavonoid molecule. The electronic structure of kaempferol was examined using NBO analysis. The assigning of the experimentally obtained IR and Raman spectra was performed after the best-fit-based comparison with theoretical spectra. The 13C and 1H NMR experimental spectra were related to the theoretically obtained values of the chemical shifts determined by the GIAO method. The correlation coefficient and the average absolute error values proved B3LYP-D3 to be an adequate method in describing the NMR parameters of kaempferol. Molecular docking analysis was carried out in order to identify the potency of inhibition of the title molecule against human procalcitonin. The inhibition activity was obtained for 10 conformations of ligand inside the protein.

scholarly journals Stability of oxidized states of ceria-supported PtOx particles under a wide range of gas-phase conditions

2021 ◽  
Author(s):  
Jon Eunan Quinlivan Domínguez ◽  
Konstantin Neyman ◽  
Albert Bruix
Keyword(s):  
Density Functional ◽  
Structural Complexity ◽  
Optimization Method ◽  
Catalyst Design ◽  
Oxidation States ◽  
Effect Of Temperature ◽  
Reaction Conditions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Wide Range

Nanostructured materials based on non-inert oxides CeO2 and PtyOx play a fundamental role in catalyst design. However, their characterization is often challenging due to their structural complexity and the tendency of the materials to change under reaction conditions. In this work, we combine calculations based on the density functional theory, a machine-learning assisted global optimization method (GOFEE) and ab initio thermodynamics to characterize stable oxidation states of ceria-supported PtyOx clusters in different environments. The collection of global minima for different stoichiometries resulting from the global optimisation effort is used to assess the effect of temperature, oxygen pressure, and support interactions on the phase diagrams, oxidation states, and structural properties of the PtyOx particles. We thus identify favoured structural motifs and O/Pt ratios, revealing that oxidized states of ceria-supported particles are more stable than reduced ones under a wide range of conditions. These results indicate that studies rationalizing activity of ceria-supported Pt clusters must consider such oxidized states, and that previous understanding of such materials obtained only with fully reduced Pt clusters may be incomplete.

Heterogeneous ozonolysis of pirimicarb and isopropalin: mechanism of ozone-induced N-dealkylation and carbonylation reactions

2012 ◽  
Vol 9 (6) ◽  
pp. 521 ◽  
Author(s):  
Bo Yang ◽  
Youfeng Wang ◽  
Wang Zhang ◽  
Changgeng Liu ◽  
Xi Shu ◽  
...  
Keyword(s):  
Reaction Mechanisms ◽  
Density Functional ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Density Functional Theory Calculations ◽  
Effective Rate ◽  
Heterogeneous Reactions ◽  
Chemical Transformations ◽  
The Density Functional Theory ◽  
First Time

Environmental contextPesticides emitted to the atmosphere can undergo extensive chemical transformations through reaction with atmospheric oxidants. Understanding the atmospheric lifetime and degradation mechanism of typical pesticides is very important to health and environmental risk assessments. We investigate the degradation products, lifetimes and reaction mechanisms of two representative pesticides oxidised by ozone in order to understand the environmental behaviours of these pesticides and their analogues. AbstractN,N-Dialkyl-substituted pyrimidine and N,N-dialkylaniline are basic structures for many pesticides. In this study, the heterogeneous reactions of O3 with pirimicarb and isopropalin adsorbed on silica particles are investigated. The N-dealkylation and carbonylation of the N,N-dialkyl group have been observed as the important reaction pathways for both pirimicarb and isopropalin. The measured effective rate constants for pirimicarb and isopropalin under room temperature (298 ± 2 K) are 1.45 × 10–18 (s.d. ±0.17) and 2.70 × 10–19 cm3 molecules–1 s–1 (±0.27). The corresponding half-life for the particulate pirimicarb and isopropalin are 5.6 and 30 days, assuming an average tropospheric ozone concentration of 40 ppbv. Detailed reaction mechanisms are proposed for the first time based on the density functional theory calculations. In addition, the transformation of –NO2 into –NHOH is observed in the ozonolysis of isopropalin, which has not been reported in previous studies.

Atomic layer deposition of diisopropylaminosilane on WO3(001) and W(110): a density functional theory study

2016 ◽  
Vol 18 (42) ◽  
pp. 29139-29146 ◽  
Author(s):  
Kyungtae Lee ◽  
Woojin Lee ◽  
Hyo Sug Lee ◽  
Jaikwang Shin ◽  
Jieun Park ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Atomic Layer ◽  
Dft Method ◽  
Decomposition Reaction ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Layer Deposition ◽  
The Density Functional Theory

The decomposition reaction mechanisms of the Si precursor, diisopropylaminosilane (DIPAS), on W(110) and WO3(001) surfaces are compared using the density functional theory (DFT) method.

scholarly journals Strain Investigation on Spin-Dependent Transport Properties of γ-Graphyne Nanoribbon Between Gold Electrodes

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yun Li ◽  
Xiaobo Li ◽  
Shidong Zhang ◽  
Liemao Cao ◽  
Fangping Ouyang ◽  
...  
Keyword(s):  
Transport Properties ◽  
High Performance ◽  
Density Functional ◽  
Strain Engineering ◽  
Molecular Junctions ◽  
Spin Splitting ◽  
Functional Theory ◽  
Spin Dependent Transport ◽  
The Density Functional Theory ◽  
Dependent Transport

AbstractStrain engineering has become one of the effective methods to tune the electronic structures of materials, which can be introduced into the molecular junction to induce some unique physical effects. The various γ-graphyne nanoribbons (γ-GYNRs) embedded between gold (Au) electrodes with strain controlling have been designed, involving the calculation of the spin-dependent transport properties by employing the density functional theory. Our calculated results exhibit that the presence of strain has a great effect on transport properties of molecular junctions, which can obviously enhance the coupling between the γ-GYNR and Au electrodes. We find that the current flowing through the strained nanojunction is larger than that of the unstrained one. What is more, the length and strained shape of the γ-GYNR serves as the important factors which affect the transport properties of molecular junctions. Simultaneously, the phenomenon of spin-splitting occurs after introducing strain into nanojunction, implying that strain engineering may be a new means to regulate the electron spin. Our work can provide theoretical basis for designing of high performance graphyne-based devices in the future.

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

scholarly journals Strain Effects on the Electronic and Thermoelectric Properties of n(PbTe)-m(Bi2Te3) System Compounds

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4086
Author(s):  
Weiliang Ma ◽  
Marie-Christine Record ◽  
Jing Tian ◽  
Pascal Boulet
Keyword(s):  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Compressive Strain ◽  
Van Der Waals Interactions ◽  
Functional Theory ◽  
Band Engineering ◽  
Seebeck Coefficients ◽  
The Density Functional Theory ◽  
P Type ◽  
Narrow Band Gap Semiconductors

Owing to their low lattice thermal conductivity, many compounds of the n(PbTe)-m(Bi2Te3) homologous series have been reported in the literature with thermoelectric (TE) properties that still need improvement. For this purpose, in this work, we have implemented the band engineering approach by applying biaxial tensile and compressive strains using the density functional theory (DFT) on various compounds of this series, namely Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5. All the fully relaxed Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5 compounds are narrow band-gap semiconductors. When applying strains, a semiconductor-to-metal transition occurs for all the compounds. Within the range of open-gap, the electrical conductivity decreases as the compressive strain increases. We also found that compressive strains cause larger Seebeck coefficients than tensile ones, with the maximum Seebeck coefficient being located at −2%, −6%, −3% and 0% strain for p-type Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5, respectively. The use of the quantum theory of atoms in molecules (QTAIM) as a complementary tool has shown that the van der Waals interactions located between the structure slabs evolve with strains as well as the topological properties of Bi2Te3 and PbBi2Te4. This study shows that the TE performance of the n(PbTe)-m(Bi2Te3) compounds is modified under strains.

scholarly journals Study on the interaction between catechin and cholesterol by the density functional theory

2020 ◽  
Vol 18 (1) ◽  
pp. 357-368
Author(s):  
Kaiwen Zheng ◽  
Kai Guo ◽  
Jing Xu ◽  
Wei Liu ◽  
Junlang Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Charge Transfer ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Micelle Formation ◽  
Aromatic Rings ◽  
Hydrogen Bond Interaction ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractCatechin – a natural polyphenol substance – has excellent antioxidant properties for the treatment of diseases, especially for cholesterol lowering. Catechin can reduce cholesterol content in micelles by forming insoluble precipitation with cholesterol, thereby reducing the absorption of cholesterol in the intestine. In this study, to better understand the molecular mechanism of catechin and cholesterol, we studied the interaction between typical catechins and cholesterol by the density functional theory. Results show that the adsorption energies between the four catechins and cholesterol are obviously stronger than that of cholesterol themselves, indicating that catechin has an advantage in reducing cholesterol micelle formation. Moreover, it is found that the molecular interactions of the complexes are mainly due to charge transfer of the aromatic rings of the catechins as well as the hydrogen bond interactions. Unlike the intuitive understanding of a complex formed by hydrogen bond interaction, which is positively correlated with the number of hydrogen bonds, the most stable complexes (epicatechin–cholesterol or epigallocatechin–cholesterol) have only one but stronger hydrogen bond, due to charge transfer of the aromatic rings of catechins.

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