http://publicationslist.org/data/meng.chong/ref-18/sdarticle.pdf

Recent Developments in Photocatalytic Water Treatment Technology: A Review

I. Introduction: Conceptual vs Fundamental andComputational Aspects of DFT1793II. Fundamental and Computational Aspects of DFT 1795A. The Basics of DFT: The Hohenberg−KohnTheorems1795B. DFT as a Tool for Calculating Atomic andMolecular Properties: The Kohn−ShamEquations1796C. Electronic Chemical Potential andElectronegativity: Bridging Computational andConceptual DFT1797III. DFT-Based Concepts and Principles 1798A. General Scheme: Nalewajski’s ChargeSensitivity Analysis1798B. Concepts and Their Calculation 18001. Electronegativity and the ElectronicChemical Potential18002. Global Hardness and Softness 18023. The Electronic Fukui Function, LocalSoftness, and Softness Kernel18074. Local Hardness and Hardness Kernel 18135. The Molecular Shape FunctionsSimilarity 18146. The Nuclear Fukui Function and ItsDerivatives18167. Spin-Polarized Generalizations 18198. Solvent Effects 18209. Time Evolution of Reactivity Indices 1821C. Principles 18221. Sanderson’s Electronegativity EqualizationPrinciple18222. Pearson’s Hard and Soft Acids andBases Principle18253. The Maximum Hardness Principle 1829IV. Applications 1833A. Atoms and Functional Groups 1833B. Molecular Properties 18381. Dipole Moment, Hardness, Softness, andRelated Properties18382. Conformation 18403. Aromaticity 1840C. Reactivity 18421. Introduction 18422. Comparison of Intramolecular ReactivitySequences18443. Comparison of Intermolecular ReactivitySequences18494. Excited States 1857D. Clusters and Catalysis 1858V. Conclusions 1860VI. Glossary of Most Important Symbols andAcronyms1860VII. Acknowledgments 1861VIII. Note Added in Proof 1862IX. References 1865

/pdf/conceptual-density-functional-theory-btz9wwrxv9.pdf

Conceptual density functional theory.

Even though heterogeneous photocatalysis appeared in many forms, photodegradation of organic pollutants has recently been the most widely investigated. By far, titania has played a much larger role in this scenario compared to other semiconductor photocatalysts due to its cost effectiveness, inert nature and photostability. Extensive literature analysis has shown many possibilities of improving the efficiency of photodecomposition over titania by combining the photoprocess with either physical or chemical operations. The resulting combined processes revealed a flexible line of action for wastewater treatment technologies. The choice of treatment method usually depends upon the composition of the wastewater. However, a lot more is needed from engineering design and modelling for successful application of the laboratory scale techniques to large-scale operation. The present review paper seeks to offer an overview of the dramatic trend in the use of the TiO 2 photocatalyst for remediation and decontamination of wastewater, report the recent work done, important achievements and problems.

/pdf/heterogeneous-photocatalytic-degradation-of-organic-3yhovgltu6.pdf

Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide : A review of fundamentals, progress and problems

A surface science perspective on TiO2 photocatalysis

A new software package, RASPA, for simulating adsorption and diffusion of molecules in flexible nanoporous materials is presented. The code implements the latest state-of-the-art algorithms for molecular dynamics and Monte Carlo (MC) in various ensembles including symplectic/measure-preserving integrators, Ewald summation, configurational-bias MC, continuous fractional component MC, reactive MC and Baker's minimisation. We show example applications of RASPA in computing coexistence properties, adsorption isotherms for single and multiple components, self- and collective diffusivities, reaction systems and visualisation. The software is released under the GNU General Public License.

/pdf/raspa-molecular-simulation-software-for-adsorption-and-g07x7edhkb.pdf

RASPA: molecular simulation software for adsorption and diffusion in flexible nanoporous materials

Probable germline gene sequences from thousands of aligned mature Ab sequences are inferred using simple computational matching to known V(D)J genes. Comparison of the germline to mature sequences in a structural region-dependent fashion allows insights into the methods that nature uses to mature Abs during the somatic hypermutation process. Four factors determine the residue type mutation patterns: biases in the germline, accessibility from single base permutations, location of mutation hotspots, and functional pressures during selection. Germline repertoires at positions that commonly contact the Ag are biased with tyrosine, serine, and tryptophan. These residue types have a high tendency to be present in mutation hotspot motifs, and their abundance is decreased during maturation by a net conversion to other types. The heavy use of tyrosines on mature Ab interfaces is thus a reflection of the germline composition rather than being due to selection during maturation. Potentially stabilizing changes such as increased proline usage and a small number of double cysteine mutations capable of forming disulfide bonds are ascribed to somatic hypermutation. Histidine is the only residue type for which usage increases in each of the interface, core, and surface regions. The net overall effect is a conversion from residue types that could provide nonspecific initial binding into a diversity of types that improve affinity and stability. Average mutation probabilities are ∼4% for core residues, ∼5% for surface residues, and ∼12% for residues in common Ag-contacting positions, excepting the those coded by the D gene.

Trends in antibody sequence changes during the somatic hypermutation process.

Ammonia TPD experiments have been carried out on protonated forms of the zeolites FAU, FER, MFI, and MOR to investigate the acid strength dependence on OH group location and Al content. Effective adsorption energy distributions are derived using a regularization method and corrected to achieve a truer measure of acid strength using nonspecific interaction energies from atomistic Monte Carlo simulations. The correction energies include all interactions not associated with the OH groups and range from 18 to 37 kJ/mol, depending on the region and the zeolite structure. In the FAU structure, we find a bimodal distribution of adsorption energies in both the supercages and the sodalite cages, with the stronger acid sites being more common in the supercages. In contrast, essentially the same acid strength for different regions in MOR is seen, though the acid strength for those sites in the side pockets may be slightly lower. For FER and MFI, the TPD gives unimodal distributions and therefore prohibits distinctio...

Characterization of Acidic OH Groups in Zeolites of Different Types: An Interpretation of NH3-TPD Results in the Light of Confinement Effects

The existence of carbenium ion species is assumed in many zeolite catalysis mechanisms. Using computational techniques that include environmental effects, a benzenium-type carbenium ion is identified in zeolite catalysts for the first time. Localization of nearby transition states indicate that this species may play an important role as an intermediate in the bimolecular m-xylene disproportionation reaction. The barrier to back-donation of the proton from the benzenium ion is at least 50 kJ/mol, meaning that this species may be spectroscopically observable. An additional carbenium ion intermediate, formed by abstraction of a hydride from m-xylene, is also predicted. The stability of this second new carbenium ion suggests that aromatic-based carbenium ions are likely to be intermediates in many zeolite-catalyzed reactions. Two types of fundamentally different fully periodic calculations support the stability predictions.

Stable mechanistically-relevant aromatic-based carbenium ions in zeolite catalysts.

A method is described for performing grand canonical Monte Carlo simulations of molecules with internal degrees of freedom. The approach is applied to adsorption of methanol and cyclohexane in the zeolite silicalite. Calculated adsorption isotherms and heats of adsorption compare well with experimental data from the literature. In addition, the simulations provide information on preferential siting of molecules in the different pores of silicalite. Binary adsorption results are also predicted for cyclohexane/methane, benzene/methane, and benzene/cyclohexane mixtures. The siting preferences of the single components result in clear segregation effects for these binary systems. Benzene and cyclohexane display preferred siting in the channel intersections, while methane adsorbs preferentially in the channels. In the case of benzene/cyclohexane, the cyclohexane adsorbs in the intersections and the benzene is pushed to the zigzag channels.

Grand canonical Monte Carlo simulations of nonrigid molecules: Siting and segregation in silicalite zeolite

Atomistic molecular dynamics simulations are used to elucidate a novel and exploitable transport phenomenon known as "molecular traffic control." Under some conditions a binary mixture of differently sized molecules in a structure possessing dual sized pores can exhibit a surprising effect. In the case examined, size segregation and other effects lead to physical separation of the two species through anisotropic diffusion. We have established the underlying causes of this effect in an equilibrium system and used simulations of a relaxing system to show that these causes also hold under nonequilibrium conditions.

Louis A. Clark

Papers

Trends in antibody sequence changes during the somatic hypermutation process.

Characterization of Acidic OH Groups in Zeolites of Different Types: An Interpretation of NH3-TPD Results in the Light of Confinement Effects

Stable mechanistically-relevant aromatic-based carbenium ions in zeolite catalysts.

Grand canonical Monte Carlo simulations of nonrigid molecules: Siting and segregation in silicalite zeolite

Molecular Traffic Control in a Nanoscale System