Depleted Oxygen Defect State Enhancing Tungsten Trioxide Photocatalysis: A Quantum Dynamics Perspective.

Oxygen vacancies generally create midgap states in transition metal oxides, which are expected to decrease the photoelectrochemical water-splitting efficiency. Recent experiments defy this expectation but leave the mechanism unclear. Focusing on the photoanode WO3 as a prototypical system, we demonstrate using nonadiabatic molecular dynamics that an oxygen vacancy suppresses nonradiative electron-hole recombination, because the defect acts as an electron reservoir instead of a recombination center. The occupied midgap electrons prefer to be populated a priori compared to the band edge transition because of a larger transition dipole moment, converting to depleted/unoccupied trap states that rapidly accept conduction band electrons and then cause trap-assisted recombination by impeding the bandgap recombination regardless of oxygen vacancy configurations. The reported results provide a fundamental understanding of the "realistic" role of the oxygen vacancies and their influence on charge-phonon dynamics and carrier lifetime. The study generates valuable insights into the design of high-performance transition metal oxide photocatalysts.

Protocol paper: Multi-site, cluster-randomized clinical trial for optimizing functional outcomes of older cancer survivors after chemotherapy.

BACKGROUND: Cancer survivors over the age of 65 have unique needs due to the higher prevalence of functional and cognitive impairment, comorbidities, geriatric syndromes, and greater need for social support after chemotherapy. In this study, we will evaluate whether a Geriatric Evaluation and Management-Survivorship (GEMS) intervention improves functional outcomes important to older cancer survivors following chemotherapy. METHODS: A cluster-randomized trial will be conducted in approximately 30 community oncology practices affiliated with the University of Rochester Cancer Center (URCC) National Cancer Institute Community Oncology Research Program (NCORP) Research Base. Participating sites will be randomized to the GEMS intervention, which includes Advanced Practice Practitioner (APP)-directed geriatric evaluation and management (GEM), and Survivorship Health Education (SHE) that is combined with Exercise for Cancer Patients (EXCAP©®), or usual care. Cancer survivors will be recruited from community oncology practices (of participating oncology physicians and APPs) after the enrolled clinicians have consented and completed a baseline survey. We will enroll 780 cancer survivors aged 65 years and older who have completed curative-intent chemotherapy for a solid tumor malignancy within four weeks of study enrollment. Cancer survivors will be asked to choose one caregiver to also participate for a total up to 780 caregivers. The primary aim is to compare the effectiveness of GEMS for improving patient-reported physical function at six months. The secondary aim is to compare effectiveness of GEMS for improving patient-reported cognitive function at six months. Tertiary aims include comparing the effectiveness of GEMS for improving: 1) Patient-reported physical function at twelve months; 2) objectively assessed physical function at six and twelve months; and 3) patient-reported cognitive function at twelve months and objectively assessed cognitive function at six and twelve months. Exploratory health care aims include: 1) Survivor satisfaction with care, 2) APP communication with primary care physicians (PCPs), 3) completion of referral appointments, and 4) hospitalizations at six and twelve months. Exploratory caregiver aims include: 1) Caregiver distress; 2) caregiver quality of life; 3) caregiver burden; and 4) satisfaction with patient care at six and twelve months. DISCUSSION: If successful, GEMS would be an option for a standardized APP-led survivorship care intervention. TRIAL REGISTRATION: ClinicalTrials.govNCT05006482, registered on August 9, 2021.

Photoinduced Energy Transfer in Linear Guest-Host Chromophores: A Computational Study.

Polymer-based guest-host systems represent a promising class of materials for efficient light-emitting diodes. The energy transfer from the polymer host to the guest is the key process in light generation. Therefore, microscopic descriptions of the different mechanisms involved in the energy transfer can contribute to enlighten the basis of the highly efficient light harvesting observed in this kind of materials. Herein, the nature of intramolecular energy transfer in a dye-end-capped conjugated polymer is explored by using atomistic nonadiabatic excited-state molecular dynamics. Linear perylene end-capped (PEC) polyindenofluorenes (PIF), consisting of n (n = 2, 4, and 6) repeat units, i.e., PEC-PIFn oligomers, are considered as model systems. After photoexcitation at the oligomer absorption maximum, an initial exciton becomes self-trapped on one of the monomer units (donors). Thereafter, an efficient ultrafast through-space energy transfer from this unit to the perylene acceptor takes place. We observe that this energy transfer occurs equally well from any monomer unit on the chain. Effective specific vibronic couplings between each monomer and the acceptor are identified. These oligomer → end-cap energy transfer steps do not match with the rates predicted by Förster-type energy transfer. The through-space and through-bond mechanisms are two distinct channels of energy transfer. The former dominates the overall process, whereas the through-bond energy transfer between indenofluorene monomer units along the oligomer backbone only makes a minor contribution.

Controlling Charge Carrier Trapping and Recombination in BiVO4 with the Oxygen Vacancy Oxidation State.

The lack of an in-depth understanding of the intrinsic oxygen vacancy (OV) defect properties in the photoanode BiVO4 limits the further improvement of its photoelectrochemical water splitting performance. To address this issue, nonadiabatic molecular dynamics simulations are performed to study the impact of OV on charge carrier lifetimes in BiVO4. The simulations show that a neutral OV gives rise to local structural distortions due to the formation of V-O-V bonds, forcing the electrons trapped on the nearer of the two V atoms to form two deep polaron-like V4+ hole traps. These localized midgap states greatly accelerate nonradiative electron-hole recombination compared to that of pristine BiVO4, reaching a time scale of several nanoseconds in good agreement with experiments. The ionized OV state restores the bandgap to its value in pristine BiVO4 and restores the charge carrier lifetimes due to the fast loss of coherence time. Our study reveals the mechanism of the detrimental role of OV in BiVO4 and provides valuable insights for improving the performance of the BiVO4 photoanode by ionizing the oxygen vacancy.

Genetic Drift Versus Climate Region Spreading Dynamics of COVID-19.

Background: The current propagation models of COVID-19 are poorly consistent with existing epidemiological data and with evidence that the SARS-CoV-2 genome is mutating, for potential aggressive evolution of the disease. Objectives: We looked for fundamental variables that were missing from current analyses. Among them were regional climate heterogeneity, viral evolution processes versus founder effects, and large-scale virus containment measures. Methods: We challenged regional versus genetic evolution models of COVID-19 at a whole-population level, over 168,089 laboratory-confirmed SARS-CoV-2 infection cases in Italy, Spain, and Scandinavia at early time-points of the pandemic. Diffusion data in Germany, France, and the United Kingdom provided a validation dataset of 210,239 additional cases. Results: Mean doubling time of COVID-19 cases was 6.63 days in Northern versus 5.38 days in Southern Italy. Spain extended this trend of faster diffusion in Southern Europe, with a doubling time of 4.2 days. Slower doubling times were observed in Sweden (9.4 days), Finland (10.8 days), and Norway (12.95 days). COVID-19 doubling time in Germany (7.0 days), France (7.5 days), and the United Kingdom (7.2 days) supported the North/South gradient model. Clusters of SARS-CoV-2 mutations upon sequential diffusion were not found to clearly correlate with regional distribution dynamics. Conclusion: Acquisition of mutations upon SARS-CoV-2 spreading failed to explain regional diffusion heterogeneity at early pandemic times. Our findings indicate that COVID-19 transmission rates are rather associated with a sharp North/South climate gradient, with faster spreading in Southern regions. Thus, warmer climate conditions may not limit SARS-CoV-2 infectivity. Very cold regions may be better spared by recurrent courses of SARS-CoV-2 infection.

Use of biochemical and protein profiles of seminal plasma to prediction of semen quality and fertility in stallions.

The identification of various substances in seminal plasma has opened the way to study their functionality. It was aimed to identify the electrophoretic protein profile (EPP) and biochemical parameters (BP) of seminal plasma (SP) as predictors of semen quality and fertility in stallion. Forty-six ejaculates from 7 fertile stallions, aged between 6-26 years, were collected from May to July and 117 mares were used to obtain fertility data. For each ejaculate, volume, sperm motility, concentration were determined and seminal plasma samples were collected to perform one- -dimensional electrophoresis and biochemical profiling. Following the estrus detection, mares were inseminated with fresh sperm. Pregnancy rates and foal rates were recorded. The concentration of 15-18 kDa molecular weight (MW) proteins has shown a positive correlation with sperm concentration and foal rate. Besides, a strong positive correlation was found between sperm concentration and 23-28 kDa MW proteins (r=0.77). The volume of 19-22 kDa MW proteins was negatively correlated with pregnancy and foal rate. Similarly, the volume of high MW proteins (173-385 kDa) correlated negatively with sperm motility and foal rate. Apart from the protein profile, while Magnesium and Glucose levels were negatively correlated with sperm quality and foal rate, Cholesterol level was a positive indicator of the quality of semen as well as the foaling rate. Moreover, the total protein level was correlated negatively with the sperm concentration whereas triglyceride was correlated positively. In conclusion, EPP and BP of seminal plasma are valuable clinical tools as predictors of fertility and semen quality in the stallion.

Photoinduced Dynamics with Constrained Vibrational Motion: FrozeNM Algorithm.

Ab initio molecular dynamics (AIMD) simulation, analyzed in terms of vibrational normal modes, is a widely used technique that facilitates understanding of complex structural motions and coupling between electronic and nuclear degrees of freedom. Usually, only a subset of vibrations is directly involved in the process of interest. The impact of these vibrations can be evaluated by performing AIMD simulations by selectively freezing certain motions. Herein, we present frozen normal mode (FrozeNM), a new algorithm to apply normal-mode constraints in AIMD simulations, as implemented in the nonadiabatic excited state molecular dynamics code. We further illustrate its capacity by analyzing the impact of normal-mode constraints on the photoinduced energy transfer between polyphenylene ethynylene dendrimer building blocks. Our results show that the electronic relaxation can be significantly slowed down by freezing a well-selected small subset of active normal modes characterized by their contributions in the direction of energy transfer. The application of these constraints reduces the nonadiabatic coupling between electronic excited states during the entire dynamical simulations. Furthermore, we validate reduced dimensionality models by freezing all the vibrations, except a few active modes. Altogether, we consider FrozeNM as a useful tool that can be broadly used to underpin the role of vibrational motion in a studied process and to formulate reduced models that describe essential physical phenomena.

Vibrational energy redistribution during donor-acceptor electronic energy transfer: criteria to identify subsets of active normal modes.

Photoinduced electronic energy transfer in conjugated donor-acceptor systems is naturally accompanied by intramolecular vibrational energy redistributions accepting an excess of electronic energy. Herein, we simulate these processes in a covalently linked donor-acceptor molecular dyad system by using nonadiabatic excited state molecular dynamics simulations. We analyze different complementary criteria to systematically identify the subset of vibrational normal modes that actively participate on the donor → acceptor (S2→ S1) electronic relaxation. We analyze energy transfer coordinates in terms of state-specific normal modes defined according to the different potential energy surfaces (PESs) involved. On one hand, we identify those vibrations that contribute the most to the direction of the main driving force on the nuclei during electronic transitions, represented by the non-adiabatic derivative coupling vector between donor and acceptor electronic states. On the other hand, we monitor normal mode transient accumulations of excess energy and their intramolecular energy redistribution fluxes. We observe that the subset of active modes varies according to the PES on which they belong and these modes experience the most significant rearrangements and mixing. Whereas the nuclear motions that promote donor → acceptor energy funneling can be localized mainly on one or two normal modes of the S2 state, they become spread out across multiple normal modes of the S1 state following the energy transfer event.

Photoexcited energy relaxation and vibronic couplings in π-conjugated carbon nanorings.

Conjugated carbon nanorings exhibit unique photophysical properties that, combined with their tunable sizes and conformations, make them suitable for a variety of practical applications. These properties are intimately associated to their strained, bent and sterically hindered cyclic structures. Herein we perform a comparative analysis of the photoinduced dynamics in carbon nanorings composed of nine phenyl units([9]CPP) and nine naphthyl units ([9]CN) respectively. The sterically demanding naphthyl units lead to large dihedral angles between neighboring units. Nevertheless, the ultrafast electronic and vibrational energy relaxation and redistribution is found to be similar for both systems. We observe that vibronic couplings, introduced by nonadiabatic energy transfer between electronic excited states, ensure the intramolecular vibrational energy redistribution through specific vibrational modes. The comparative impact of the internal conversion process on the exciton spatial localization and intra-ring migration indicates that naphthyl units in [9]CN achieve more efficient but less dynamical self-trapping compared to that of phenyl units in [9]CPP. That is, during the photoinduced process, the exciton in [9]CN is more static and localized than the exciton in [9]CPP. The internal conversion processes take place through a specific set of middle- to high-frequency normal modes, which directly influence the spatial exciton redistribution during the internal conversion, self-trapping and intra-ring migration.

Electronic Energy Relaxation in a Photoexcited Fully Fused Edge-Sharing Carbon Nanobelt.

Carbon nanobelts are cylindrical molecules composed of fully fused edge-sharing arene rings. Because of their aesthetically appealing structures, they acquire unusual optoelectronic properties that are potentially suitable for a range of applications in nanoelectronics and photonics. Nevertheless, the very limited success of their synthesis has led to their photophysical properties remaining largely unknown. Compared to that of carbon nanorings (arenes linked by single bonds), the strong structural rigidity of nanobelts prevents significant deformations away from the original high-symmetry conformation and, therefore, impacts their photophysical properties. Herein, we study the photoinduced dynamics of a successfully synthesized belt segment of (6,6)CNT (carbon nanotube). Modeling this process with nonadiabatic excited state molecular dynamics simulations uncovers the critical role played by the changes in excited state wave function localization on the different types of carbon atoms. This allows a detailed description of the excited state dynamics and spatial exciton evolution throughout the nanobelt scaffold. Our results provide detailed information about the excited state electronic properties and internal conversion rates that is potentially useful for designing nanobelts for nanoelectronic and photonic applications.

Vibronic Quantum Beating between Electronic Excited States in a Heterodimer.

Energy transfer in multichromophoric molecules can be affected by coherences that are induced by the electronic and vibrational couplings between chromophore units. Coherent electron-vibrational dynamics can persist at the subpicosecond time scale even at room temperature. Furthermore, wave-like localized-delocalized motions of the electronic wave function can be modulated by vibrations that actively participate in the intermolecular energy transfer process. Herein, nonadiabatic excited state molecular dynamics simulations have been performed on a rigid synthetic heterodimer that has been proposed as a simplified model for investigating the role and mechanism of coherent energy transfer in multichromophoric systems. Both surface hopping (SH) and Ehrenfest approaches (EHR) have been considered. After photoexcitation of the system at room temperature, EHR simulations reveal an ultrafast beating of electronic populations between the two lowest electronic states. These oscillations are not observed at low temperature and have vibrational origins. Furthermore, they cannot be reproduced using SH approach. This periodic behavior of electronic populations induces oscillations in the spatial localization of the electronic transition density between monomers. Vibrations whose frequencies are near-resonant with energy difference between the two lowest electronic excited states are in the range of the electronic population beating, and they are the ones that contribute the most to the coherent dynamics of these electronic transitions.

Nucleoli and Promyelocytic Leukemia Protein (PML) bodies are phase separated nuclear protein quality control compartments for misfolded proteins.

We uncovered a role for nucleoli and PML-bodies as phase-separated protein quality control organelles that compartmentalize protein quality control factors and misfolded proteins for their efficient clearance. Failure to dispose misfolded proteins converts nucleoli and PML-bodies into a solid state that immobilizes ubiquitin, limiting its recycling for genome integrity maintenance.

Fatty Acid and Retinol-Binding Protein: Unusual Protein Conformational and Cavity Changes Dictated by Ligand Fluctuations.

Lipid-binding proteins (LBPs) are soluble proteins responsible for the uptake, transport, and storage of a large variety of hydrophobic lipophilic molecules including fatty acids, steroids, and other lipids in the cellular environment. Among the LBPs, fatty acid binding proteins (FABPs) present preferential binding affinities for long-chain fatty acids. While most of FABPs in vertebrates and invertebrates present similar ß-barrel structures with ligands accommodated in their central cavity, parasitic nematode worms exhibit additional unusual α-helix rich fatty acid- and retinol-binding proteins (FAR). Herein, we report the comparison of extended molecular dynamics (MD) simulations performed on the ligand-free and palmitic acid-bond states of the Necator americanus FAR-1 (Na-FAR-1) with respect to other classical ß-barrel FABPs. Principal component analysis (PCA) has been used to identify the different conformations adopted by each system during MD simulations. The α-helix fold encompasses a complex internal ligand-binding cavity with a remarkable conformational plasticity that allows reversible switching between distinct states in the holo-Na-FAR-1. The cavity can change up to one-third of its size affected by conformational changes of the protein-ligand complex. Besides, the ligand inside the cavity is not fixed but experiences large conformational changes between bent and stretched conformations. These changes in the ligand conformation follow changes in the cavity size dictated by the transient protein conformation. On the contrary, protein-ligand complex in ß-barrel FABPs fluctuates around a unique conformation. The significantly more flexible holo-Na-FAR-1 ligand-cavity explains its larger ligand multiplicity respect to ß-barrel FABPs.

Photoinduced non-adiabatic energy transfer pathways in dendrimer building blocks.

The efficiency of the intramolecular energy transfer in light harvesting dendrimers is determined by their well-defined architecture with high degree of order. After photoexcitation, through-space and through-bond energy transfer mechanisms can take place, involving vectorial exciton migration among different chromophores within dendrimer highly branched structures. Their inherent intramolecular energy gradient depends on how the multiple chromophoric units have been assembled, subject to their inter-connects, spatial distances, and orientations. Herein, we compare the photoinduced nonadiabatic molecular dynamics simulations performed on a set of different combinations of a chain of linked dendrimer building blocks composed of two-, three-, and four-ring linear polyphenylene chromophoric units. The calculations are performed with the recently developed ab initio multiple cloning-time dependent diabatic basis implementation of the Multiconfigurational Ehrenfest (MCE) approach. Despite differences in short time relaxation pathways and different initial exciton localization, at longer time scales, electronic relaxation rates and exciton final redistributions are very similar for all combinations. Unlike the systems composed of two building blocks, considered previously, for the larger 3 block systems here we observe that bifurcation of the wave function accounted by cloning is important. In all the systems considered in this work, at the time scale of few hundreds of femtoseconds, cloning enhances the electronic energy relaxation by ∼13% compared to that of the MCE method without cloning. Thus, accurate description of quantum effects is essential for understanding of the energy exchange in dendrimers both at short and long time scales.

Energy transfer and spatial scrambling of an exciton in a conjugated dendrimer.

Photoexcitation of multichromophoric light harvesting molecules induces a number of intramolecular electronic energy relaxation and redistribution pathways that can ultimately lead to ultrafast exciton self-trapping on a single chromophore unit. We investigate the photoinduced processes that take place on a phenylene-ethynylene dendrimer, consisting of nine equivalent linear chromophore units or branches. meta-Substituted links between branches break the conjugation giving rise to weak couplings between them and to localized excitations. Our nonadiabatic excited-state molecular dynamics simulations reveal that the ultrafast internal conversion process to the lowest excited state is accompanied by an inner → outer inter-branch migration of the exciton due to the entropic bias associated with energetically equivalent conjugated segments. The electronic energy redistribution among chromophore units occurs through several possible pathways in which through-bond transport and through-space exciton hopping mechanisms can be distinguished. Besides, triple bond excitations coincide with the localization of the electronic transition densities, suggesting that the intramolecular energy redistribution is a concerted electronic and vibrational energy transfer process.

Millimeter-Wave Beam Scattering by Field-Aligned Blobs in Simple Magnetized Toroidal Plasmas.

The first direct experimental measurements of the scattering of a millimeter-wave beam by plasma blobs in a simple magnetized torus are reported. The wavelength of the beam is comparable to the characteristic size of the blob. In situ Langmuir probe measurements show that fluctuations of the electron density induce correlated fluctuations of the transmitted power. A first-principles full-wave model, using conditionally sampled 2D electron density profiles, predicts fluctuations of the millimeter-wave power that are in agreement with experiments.

Optically isolated millimeter-wave detector for the Toroidal Plasma Experiment.

We have designed and built an optically isolated millimeter-wave detection system to prevent interference from a nearby, powerful, 2.45 GHz microwave source in millimeter-wave propagation experiments in the TORoroidal Plasma EXperiment (TORPEX). A series of tests demonstrates excellent system noise immunity and the ability to observe effects that cannot be resolved in a setup using a bare Schottky diode detector.

Photoinduced dynamics in cycloparaphenylenes: planarization, electron-phonon coupling, localization and intra-ring migration of the electronic excitation.

Cycloparaphenylenes represent the smallest possible fragments of armchair carbon nanotubes. Due to their cyclic and curved conjugation, these nanohoops own unique photophysical properties. Herein, the internal conversion processes of cycloparaphenylenes of sizes 9 through 16 are simulated using Non-Adiabatic Excited States Molecular Dynamics. In order to analyze effects of increased conformational disorder, simulations are done at both low temperature (10 K) and room temperature (300 K). We found the photoexcitation and subsequent electronic energy relaxation and redistribution lead to different structural and electronic signatures such as planarization of the chain, electron-phonon couplings, wavefunction localization, and intra-ring migration of excitons. During excited state dynamics on a picosecond time-scale, an electronic excitation becomes partially localized on a portion of the ring (about 3-5 phenyl rings), which is not a mere static contraction of the wavefunction. In a process of non-radiative relaxation involving non-adiabatic transitions, the latter exhibits significant dynamical mobility by sampling uniformly the entire molecular structure. Such randomized migration involving all phenyl rings, occurs in a wave-like fashion coupled to vibrational degrees of freedom. These results can be connected to unpolarized emission observed in single-molecule fluorescence experiments. Observed intra-ring energy transfer is subdued for lower temperatures and adiabatic dynamics involving low-energy photoexcitation to the first excited state. Overall our analysis provides a detailed description of photo excited dynamics in molecular systems with circular geometry, outlines size-dependent trends and connotes specific spectroscopic signatures appearing in time-resolved experimental probes.

A history of Edinburgh's medical museums.

Edinburgh has a wealth of medical collections, thanks not only to its role in the Enlightenment and the diaspora of graduates from the large medical school, but also to recent developments in medical heritage. Concentrating on the collections of the University of Edinburgh's Anatomy Department and Surgeons' Hall Museums at the Royal College of Surgeons of Edinburgh, this paper charts the complex and connected histories of the material culture of anatomy, pathology and surgery in the city. What roles did museums play, from their 18th century origins to their 21st century resurgence, and who used them?

Ultrafast electronic energy relaxation in a conjugated dendrimer leading to inter-branch energy redistribution.

Dendrimers are arrays of coupled chromophores, where the energy of each unit depends on its structure and conformation. The light harvesting and energy funneling properties are strongly dependent on their highly branched conjugated architecture. Herein, the photoexcitation and subsequent ultrafast electronic energy relaxation and redistribution of a first generation dendrimer (1) are analyzed combining theoretical and experimental studies. Dendrimer 1 consists of three linear phenylene-ethynylene (PE) units, or branches, attached in the meta position to a central group opening up the possibility of inter-branch energy transfer. Excited state dynamics are explored using both time-resolved spectroscopy and non-adiabatic excited state molecular dynamics simulations. Our results indicate a subpicosecond loss of anisotropy due to an initial excitation into several states with different spatial localizations, followed by exciton self-trapping on different units. This exciton hops between branches. The absence of an energy gradient leads to an ultrafast energy redistribution among isoenergetic chromophore units. At long times we observe similar probabilities for each branch to retain significant contributions of the transition density of the lowest electronic excited-state. The observed unpolarized emission is attributed to the contraction of the electronic wavefunction onto a single branch with frequent interbranch hops, and not to its delocalization over the whole dendrimer.