Using G0W0G_0W_0 Level Alignment to Identify Catechol's Structure on TiO2_2(110)

We perform state-of-the-art calculations for a prototypical dye sensitized solar cell: catechol on rutile TiO$_2$(110). Catechol is often used as an anchoring group for larger more complex organic and inorganic dyes on TiO$_2$ and forms a type II heterojunctions on TiO$_2$(110). In particular, we compare quasiparticle (QP) $G_0W_0$ with hybrid exchange correlation functional (HSE) density functional theory (DFT) calculations for the catechol-rutile TiO$_2$(110) interface. In so doing, we provide a theoretical interpretation of ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES) experiments for this prototypical system. Specifically, we demonstrate that the position, presence, and intensity of peaks associated with catechol's HOMO, intermolecular OH$-$O bonds, and interfacial hydrogen bonds to the surface bridging O atoms (O$_{br}$H$-$C and O$_{br}$H$-$O) may be used to fingerprint deprotonation of catechol's OH anchoring groups. Furthermore, our results suggest deprotonation of these groups, while being nearly isoenergetic at high coverages, may significantly increase the photovoltaic efficiency of catechol$-$TiO$_2$(110) interfaces.Comment: 7 pages, 4 figures, corrected table

Coverage Dependence of the Level Alignment for Methanol on TiO2_2(110)

Electronic level alignment at the interface between an adsorbed molecular layer and a semiconducting substrate determines the activity and efficiency of many photocatalytic materials. We perform $G_0W_0$ calculations to determine the coverage dependence of the level alignment for a prototypical photocatalytic interface: 1/2 and 1 monolayer (ML) intact and dissociated CH$_3$OH on rutile TiO$_2$(110). We find changes in the wavefunction's spatial distribution, and a consequent renormalization of the quasiparticle energy levels, as a function of CH$_3$OH coverage and dissociation. Our results suggest that the occupied molecular levels responsible for hole trapping are not those observed in the ultraviolet photoemission spectroscopy (UPS) spectrum. Rather, they are those of isolated CH$_3$O on the surface. We find the unoccupied molecular levels have either 2D character with weight above the surface at 1 ML coverage, or significant hybridization with the surface at 1/2 ML coverage. These results suggest the resonance observed in the two photon phooemission (2PP) spectrum arises from excitations to unoccupied "Wet electron" levels with 2D character.Comment: 8 pages, 5 figures, 1 tabl

Using Wave-Packet Interferometry to Monitor the External Vibrational Control of Electronic Excitation Transfer

We investigate the control of electronic energy transfer in molecular dimers through the preparation of specific vibrational coherences prior to electronic excitation, and its observation by nonlinear wave-packet interferometry. Laser-driven coherent nuclear motion can affect the instantaneous resonance between site-excited electronic states and thereby influence short-time electronic excitation transfer (EET). We first illustrate this control mechanism with calculations on a dimer whose constituent monomers undergo harmonic vibrations. We then consider the use of nonlinear wave-packet interferometry (nl-WPI) experiments to monitor the nuclear dynamics accompanying EET in general dimer complexes following impulsive vibrational excitation by a sub-resonant control pulse (or control pulse sequence). In measurements of this kind, two pairs of polarized phase-related femtosecond pulses following the control pulse generate superpositions of coherent nuclear wave packets in optically accessible electronic states. Interference contributions to the time- and frequency-integrated fluorescence signal due to overlaps among the superposed wave packets provide amplitude-level information on the nuclear and electronic dynamics. We derive the basic expression for a control-pulse-dependent nl-WPI signal. The electronic transition moments of the constituent monomers are assumed to have a fixed relative orientation, while the overall orientation of the complex is distributed isotropically. We include the limiting case of coincident arrival by pulses within each phase-related pair in which control-influenced nl-WPI reduces to a fluorescence-detected pump-probe difference experiment. Numerical calculations of pump-probe signals based on these theoretical expressions are presented in the following paper

Comparing quasiparticle H2_2O level alignment on anatase and rutile TiO2_2

Knowledge of the molecular frontier levels' alignment in the ground state can be used to predict the photocatalytic activity of an interface. The position of the adsorbate's highest occupied molecular orbital (HOMO) levels relative to the substrate's valence band maximum (VBM) in the interface describes the favorability of photogenerated hole transfer from the VBM to the adsorbed molecule. This is a key quantity for assessing and comparing H$_2$O photooxidation activities on two prototypical photocatalytic TiO$_2$ surfaces: anatase (A)-TiO$_2$(101) and rutile (R)-TiO$_2$(110). Using the projected density of states (DOS) from state-of-the-art quasiparticle (QP) $G_0W_0$ calculations, we assess the relative photocatalytic activity of intact and dissociated H$_2$O on coordinately unsaturated (Ti$_{\textit{cus}}$) sites of idealized stoichiometric A-TiO$_2$(101)/R-TiO$_2$(110) and bridging O vacancies (O$_{\textit{br}}^{\textit{vac}}$) of defective A-TiO$_{2-x}$(101)/R-TiO$_{2-x}$(110) surfaces ($x=\frac{1}{4},\frac{1}{8}$) for various coverages. Such a many-body treatment is necessary to correctly describe the anisotropic screening of electron-electron interactions at a photocatalytic interface, and hence obtain accurate interfacial level alignments. The more favorable ground state HOMO level alignment for A-TiO$_2$(101) may explain why the anatase polymorph shows higher photocatalytic activities than the rutile polymorph. Our results indicate that (1) hole trapping is more favored on A-TiO$_2$(101) than R-TiO$_2$(110) and (2) HO@Ti$_{\textit{cus}}$ is more photocatalytically active than intact H$_2$O@Ti$_{\textit{cus}}$

Level alignment of a prototypical photocatalytic system: Methanol on TiO2(110)

Photocatalytic and photovoltaic activity depends on the optimal alignment of electronic levels at the molecule/semiconductor interface. Establishing level alignment experimentally is complicated by the uncertain chemical identity of the surface species. We address the assignment of the occupied and empty electronic levels for the prototypical photocatalytic system of methanol on a rutile TiO2 (110) surface. Using many-body quasiparticle (QP) techniques we show that the frontier levels measured in ultraviolet photoelectron and two photon photoemission spectroscopy experiments can be assigned with confidence to the molecularly chemisorbed methanol, rather than its decomposition product, the methoxy species. We find the highest occupied molecular orbital (HOMO) of the methoxy species is much closer to the valence band maximum, suggesting why it is more photocatalytically active than the methanol molecule. We develop a general semi-quantitative model for predicting many-body QP energies based on the appropriate description of electronic screening within the bulk, molecular or vacuum regions of the wavefunctions at molecule/semiconductor interfaces.Comment: 5 pages, 5 figure

Las métricas de investigación y su uso responsable

Universidad Pablo de Olavid

Emotional expression in psychotherapy: the role of the therapist in promoting good treatment outcomes

openL’elaborato consiste in un approfondimento sull’espressione emotiva in ambito psicoterapeutico: in particolare viene analizzata l’efficacia di tale elemento della relazione terapeutica e il suo ruolo all’interno delle sessioni di terapia. Il costrutto viene considerato sia da un punto di vista di espressione delle emozioni da parte del cliente, che all’interno del vissuto del terapeuta e nel modo in cui quest’ultimo può favorire esiti positivi di trattamento. Dopo alcune brevi considerazioni generali sul movimento di ricerca in psicoterapia, con un focus sulla ricerca sul processo e sulle relazioni psicoterapeutiche supportate empiricamente, viene descritta l’espressione emotiva in psicoterapia attraverso diversi riferimenti teorici. Sono presentate due meta-analisi che hanno verificato l’associazione positiva dell’espressione affettiva del paziente e del terapeuta con buoni risultati clinici. Seguono ulteriori valutazioni empiriche focalizzate sulla persona del terapeuta impegnata nel difficile lavoro di gestione delle emozioni, proprie e dei clienti. Nello specifico sono riportati studi che hanno indagato i modelli di esperienza emotiva di psicoterapeuti con background culturale e variabili demografiche differenti, e alcune abilità terapeutiche associate all’espressione emotiva del cliente. I risultati sono discussi nell’ottica di evidenziare l’importanza di lavorare con le emozioni all’interno delle psicoterapie; in particolare i terapeuti dovrebbero ricevere un’adeguata ‘formazione emotiva’ per riuscire ad utilizzare la propria espressione emotiva come uno strumento favorevole al progresso terapeutico, nonché protettivo per la loro persona. Si conclude suggerendo di ampliare le indagini della ricerca sulle emozioni a come i terapeuti di vari orientamenti torici possono riconoscere e facilitare l’espressione emotiva produttiva di clienti diversi. Un approfondimento dovrebbe riguardare come modellare le emozioni all’interno della cornice professionale e l’impatto del lavoro emotivo dello psicologo sul suo benessere personale. Inoltre data la forte componente culturale e sociale di tale costrutto sarebbe importante analizzarlo prendendo in considerazione campioni composti da etnie, generi ed età differenti

Barriers to implementing energy conscious design in housing.

Thesis. 1979. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography: leaves 76-78.M.Arch.A.S

Proteomics Based Process And Cell Line Development Applied To A Mammalian Therapeutic Enzyme

Recombinant human Acid Alpha Glucosidase (GAA) is the therapeutic enzyme used for the treatment of Pompe disease, a rare genetic disorder characterised by GAA deficiency in the cell lysosomes. The manufacturing process for GAA can be challenging, in part due to protease degradation. The overall goal of this project was to understand the effects of GAA overexpression on cell lysosomal phenotype and host cell protein (HCP) release, and any resultant consequences for protease levels and ease of manufacture. To do this we first generated a human recombinant GAA producing stable CHO clonal cell line and then developed a two-step bioprocess based on capture chromatographic step anion exchange (IEX) and intermediate hydrophobic interaction (HIC). The purity of GAA after HIC was determined via LC/MSMS to be above 80%. We then collected images of cell lysosomes via transmission electron microscopy (TEM) and compared the resulting data with that from a Null CHO cell line. TEM imaging revealed 72% of all lysosomes in the GAA cell line were engorged indicating extensive cell stress; by comparison, only 8% of lysosomes in the Null CHO had a similar phenotype. Furthermore, comparison of the HCP profile among cell lines [GAA, mAb and Null] capture eluates, showed that while most HCPs released were common across them, some were unique to the GAA producer, implying that cell stress caused by overexpression of GAA has a molecule specific effect on HCP release. Protease analysis via zymograms showed an overall reduction in proteolytic activity after the capture step but also revealed the presence of co-eluting proteases at approximately 80 KDa, which MS analysis putatively identified as dipeptidyl peptidase 3 and prolyl endopeptidase