Rational Design of Fe Single Sites Supported on Hierarchical Zeolites Atomic Layer Deposition for Few-Walled Carbon Nanotube Production.

Metal single-site catalysts have recently played an essential role in catalysis due to their enhanced activity, selectivity, and precise reaction control compared to those of conventional metal cluster catalysts. However, the rational design and catalytic application of metal single-site catalysts are still in the early stages of development. In this contribution, we report the rational design of Fe single sites incorporated in a hierarchical ZSM-5 atomic layer deposition (ALD).

Increasing Lovastatin Production by Re-routing the Precursors Flow of Aspergillus terreus via Metabolic Engineering.

Lovastatin is an anti-cholesterol medicine that is commonly prescribed to manage cholesterol levels, and minimise the risk of suffering from heart-related diseases. Aspergillus terreus (ATCC 20542) supplied with carbohydrates or sugar alcohols can produce lovastatin. The present work explored the application of metabolic engineering in A.

Selective heterogeneous hydrodeoxygenation of acetophenone over monometallic and bimetallic Pt-Co catalyst.

The hydrodeoxygenation (HDO) of acetophenone was evaluated in liquid phase and gas phase over monometallic Pt/SiO, Co/SiO and bimetallic Pt-Co/SiO catalysts. The influence of reaction time and loading of the catalyst were analysed by following the conversion and products selectivity. Phenylethanol, cyclohexylethanone and cyclohexylethanol are the main products of reaction using the Pt/SiO catalyst.

Biomass-derived nanocarbon materials for biological applications: challenges and prospects.

Biomass-derived nanocarbons (BNCs) have attracted significant research interests due to their promising economic and environmental benefits. Following their extensive uses in physical and chemical research domains, BNCs are now growing in biological applications. However, their practical biological applications are still in their infancy, requiring critical evaluations and strategic directions, which are provided in this review.

Atomic order, electronic structure and thermodynamic stability of nickel aluminate.

The atomic order, electronic structure and thermodynamic stability of nickel aluminate, NiAl2O4, have been analyzed using periodic density functional theory and cluster expansion. NiAl2O4 forms a tetragonal structure with P4122 space group. At temperatures below 800 K, it is an inverse spinel, with Ni occupying the octahedral sites and Al occupying both the octahedral and the tetrahedral sites.

Binding and activation of ethylene on tungsten carbide and platinum surfaces.

Density functional calculations were used to evaluate the ability of cubic and hexagonal phases of tungsten carbide to bind ethylene, as a model compound of unsaturated hydrocarbons, since its adsorption is the first step in important catalytic processes. The calculations give the following trend in stability: α-WC(0001)-C > α-WC(0001)-W > Pt(111) > γ-WC(001), with the binding energy varying in the range of -0.72 to -2.

Improved lovastatin production by inhibiting (+)-geodin biosynthesis in Aspergillus terreus.

Lovastatin is widely prescribed to reduce elevated levels of cholesterol and prevent heart-related diseases. Cultivation of Aspergillus terreus (ATCC 20542) with carbohydrates or low-value feedstocks such as glycerol produces lovastatin as a secondary metabolite and (+)-geodin as a by-product. An A.

The effect of surface coverage on N, NO and NO formation over Pt(111).

The effect of surface coverage of species, θ, on the kinetic parameters of N2, NO and N2O formation in a system simulating ammonia oxidation over Pt(111) has been studied by using periodic density functional theory (DFT). The energy barriers for product formation decrease as θ increases, with the effect being more significant above 0.25 ML.

Overexpression of acetyl-CoA carboxylase in Aspergillus terreus to increase lovastatin production.

The present work describes the application of homologous recombination techniques in a wild-type Aspergillus terreus (ATCC 20542) strain to increase the flow of precursors towards the lovastatin biosynthesis pathway. A new strain was generated to overexpress acetyl-CoA carboxylase (ACCase) by replacing the native ACCase promoter with a strong constitutive PadhA promoter from Aspergillus nidulans. Glycerol and a mixture of lactose and glycerol were used independently as the carbon feedstock to determine the degree of response by the A.

In situ synchrotron XRD analysis of the kinetics of spodumene phase transitions.

The phase transition by thermal activation of natural α-spodumene was followed by in situ synchrotron XRD in the temperature range 896 to 940 °C. We observed both β- and γ-spodumene as primary products in approximately equal proportions. The rate of the α-spodumene inversion is first order and highly sensitive to temperature (apparent activation energy ∼800 kJ mol-1).

Unravelling Some of the Key Transformations in the Hydrothermal Liquefaction of Lignin.

Using both experimental and computational methods, focusing on intermediates and model compounds, some of the main features of the reaction mechanisms that operate during the hydrothermal processing of lignin were elucidated. Key reaction pathways and their connection to different structural features of lignin were proposed. Under neutral conditions, subcritical water was demonstrated to act as a bifunctional acid/base catalyst for the dissection of lignin structures.

Effect of the Local Atomic Ordering on the Stability of β-Spodumene.

This study focuses on the relative energetic stability of β-spodumene configurations with different atomic ordering, evaluated using electronic structure methods based on static periodic density functional theory. We found that β-spodumene configurations with a framework containing exclusively Al-O-Si linkages are energetically the most stable, consistent with the aluminum avoidance principle. A correlation between the interstitial sites occupied by lithium and the stability of the configuration was established: highly stable configurations contain greater proportions of lithium associated with the edges of AlO4 tetrahedrons.

Local site selectivity and conformational structures in the glycosidic bond scission of cellobiose.

Car-Parrinello molecular dynamics combined with metadynamics simulations were used to study the acid-catalyzed hydrolysis of cellobiose (CB) in aqueous solution. The hydrolysis was studied in two steps. Step 1 involves the proton transfer from solvent to CB and dissociation of the glycosidic bond to β-glucose and oxacarbenium ion species.

Molecular dynamics study of Acid-catalyzed hydrolysis of dimethyl ether in aqueous solution.

The acid-catalyzed hydrolysis of dimethyl ether (DME) to methanol was examined using ab initio density functional metadynamics simulations. Diffusion of the acid proton from the aqueous medium, leading to the formation of a protonated DME, is 12.3 kcal mol(-1) activated and 9.

Conformational and thermodynamic properties of gaseous levulinic acid.

Molecular modeling is used to determine low-energy conformational structures and thermodynamic properties of levulinic acid in the gas phase. Structure and IR vibrational frequencies are obtained using density functional and Møller-Plesset perturbation theories. Electronic energies are computed using G3//B3LYP and CBS-QB3 model chemistries.

DFT analysis of the reaction paths of formaldehyde decomposition on silver.

Periodic density functional theory is used to study the dehydrogenation of formaldehyde (CH(2)O) on the Ag(111) surface and in the presence of adsorbed oxygen or hydroxyl species. Thermodynamic and kinetic parameters of elementary surface reactions have been determined. The dehydrogenation of CH(2)O on clean Ag(111) is thermodynamically and kinetically unfavorable.

Reaction of hydrogen with Ag(111): binding states, minimum energy paths, and kinetics.

The interaction of atomic and molecular hydrogen with the Ag(111) surface is studied using periodic density functional total-energy calculations. This paper focuses on the site preference for adsorption, ordered structures, and energy barriers for H diffusion and H recombination. Chemisorbed H atoms are unstable with respect to the H(2) molecule in all adsorption sites below monolayer coverage.

Gas-phase interaction of H2S with O2: A kinetic and quantum chemistry study of the potential energy surface.

Quantum chemical calculations were carried out to study the interaction of hydrogen sulfide with molecular oxygen in the gas phase. The basic mechanism, the rates of reaction, and the potential energy surface were calculated. Isomers and transition states that connect the reactants with intermediates and products of reaction were identified using the G2 method and B3LYP/6-311+G(3df,2p) functional.