Acoustic enhancement of polymer/ZnO nanorod photovoltaic device performance.

Acoustic vibrations are shown to enhance the photovoltaic efficiency of a P3HT/ZnO nanorod solar cell by up to 45%, correlated to a three-fold increase in charge carrier lifetime. This is assigned to the generation of piezoelectric dipoles in the ZnO nanorods, indicating that the efficiency of solar cells may be enhanced in the presence of ambient vibrations by the use of piezoelectric materials.

Rinne revisited: steel versus aluminum tuning forks.

Objective: (1) Determine whether tuning fork material (aluminum vs stainless steel) affects Rinne testing in the clinical assessment of conductive hearing loss (CHL). (2) Determine the relative acoustic and mechanical outputs of 512-Hz tuning forks made of aluminum and stainless steel.

Study Design: Prospective, observational.

Aging compounds western diet-associated large artery endothelial dysfunction in mice: prevention by voluntary aerobic exercise.

We tested the hypothesis that aging will exacerbate the negative vascular consequences of exposure to a common physiological stressor, i.e., consumption of a "western" (high fat/high sucrose) diet (WD), by inducing superoxide-associated reductions in nitric oxide (NO) bioavailability, and that this would be prevented by voluntary aerobic exercise.

Performance enhancement of fullerene-based solar cells by light processing.

A key challenge to the commercialization of organic bulk heterojunction solar cells is the achievement of morphological stability, particularly under thermal stress conditions. Here we show that a low-level light exposure processing step during fabrication of blend polymer:PC60BM solar cells can result in a 10-fold increase in device thermal stability and, under certain conditions, enhanced device performance. The enhanced stability is linked to the light-induced oligomerization of PC60BM that effectively hinders their diffusion and crystallization in the blend.

Molecular approaches to solar energy conversion: the energetic cost of charge separation from molecular-excited states.

This review starts with a brief overview of the technological potential of molecular-based solar cell technologies. It then goes on to focus on the core scientific challenge associated with using molecular light-absorbing materials for solar energy conversion, namely the separation of short-lived, molecular-excited states into sufficiently long-lived, energetic, separated charges capable of generating an external photocurrent. Comparisons are made between different molecular-based solar cell technologies, with particular focus on the function of dye-sensitized photoelectrochemical solar cells as well as parallels with the function of photosynthetic reaction centres.

AutoGrow 3.0: an improved algorithm for chemically tractable, semi-automated protein inhibitor design.

We here present an improved version of AutoGrow (version 3.0), an evolutionary algorithm that works in conjunction with existing open-source software to automatically optimize candidate ligands for predicted binding affinity and other druglike properties. Though no substitute for the medicinal chemist, AutoGrow 3.

Comparing neural-network scoring functions and the state of the art: applications to common library screening.

We compare established docking programs, AutoDock Vina and Schrödinger's Glide, to the recently published NNScore scoring functions. As expected, the best protocol to use in a virtual-screening project is highly dependent on the target receptor being studied. However, the mean screening performance obtained when candidate ligands are docked with Vina and rescored with NNScore 1.

Charge carrier separation in nanostructured TiO2 photoelectrodes for water splitting.

There is intense interest in developing new novel nanostructured photoanodes for water splitting. It is therefore important that methods to analyze the effect of nanostructuring on water splitting yields are developed in order to rationalize the relative merits of this approach for different materials. In this study the dependence of charge separation efficiency (η(sep)) on potential during photoelectrochemical water splitting at pH 2 has been quantified in a model electrode system (nanocrystalline, mesoporous TiO2) using two independent methods.

Pelvic fracture-related urethral and bladder injury.

Major pelvic ring fracture (PRF) due to blunt trauma results in lower urinary tract injury (LUTI) in up to 10% of cases. Significant comorbidity may result and this is particularly the case for unrecognised injury. The increase in military injuries due to improvised explosive devices in recent conflicts has revealed a complex injury cohort.

BPTs: thiophene-flanked benzodipyrrolidone conjugated polymers for ambipolar organic transistors.

A series of novel thiophene-flanked benzodipyrrolidone (BPT)-based alternating copolymers are synthesised, their optical and electrical properties evaluated. The BPT unit promotes a conjugated, planar polymer backbone, with a low bandgap, primarily due to low lying LUMO energy levels. Copolymerisation with thiophene exhibits well balanced ambipolar organic field-effect transistor performance, with electron and hole mobilities 0.

Limits on the Fill Factor in Organic Photovoltaics: Distinguishing Nongeminate and Geminate Recombination Mechanisms.

In this Letter, we present transient optoelectronic experimental studies of the recombination processes limiting the fill factor (FF) in three conjugated polymer:fullerene systems, poly(3-hexylthiophene) (P3HT) and two lower-band-gap polymers that exhibit lower FFs poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole) (PCPDTBT) and poly(2,7-(9,9-dioctylfluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)) (APFO-3). Using transient absorption spectroscopy, charge extraction, and transient photovoltage experiments, we show that the lower FF observed for the PCPDTBT-based device results from enhanced nongeminate recombination even at short circuit, In contrast, we show that for APFO-3 devices, the FF is primarily limited by a voltage-dependent free charge generation, which we assign to a geminate recombination process.

The influence of polymer purification on photovoltaic device performance of a series of indacenodithiophene donor polymers.

A series of low bandgap indacenodithiophene polymers is purified by recycling SEC in order to isolate narrow polydispersity fractions. This additional purification step is found to have a significant beneficial influence on the solar cell performance and the reasons for this performance increase are investigated.

Fused dithienogermolodithiophene low band gap polymers for high-performance organic solar cells without processing additives.

We report the synthesis of a novel ladder-type fused ring donor, dithienogermolodithiophene, in which two thieno[3,2-b]thiophene units are held coplanar by a bridging dialkyl germanium. Polymerization of this extended monomer with N-octylthienopyrrolodione by Stille polycondensation afforded a polymer, pDTTG-TPD, with an optical band gap of 1.75 eV combined with a high ionization potential.

Correlating triplet yield, singlet oxygen generation and photochemical stability in polymer/fullerene blend films.

The photostability of two donor polymers, DPP-TT-T and PTB7, is compared in neat films and blend films with PC(71)BM. In both neat and blend films, PTB7 is shown to be relatively unstable. This observation is shown to correlate with transient optical studies of long lived polymer triplets and with molecular probe studies of singlet oxygen yields.

Charge-Transfer State Dynamics Following Hole and Electron Transfer in Organic Photovoltaic Devices.

The formation of bound electron-hole pairs, also called charge-transfer (CT) states, in organic-based photovoltaic devices is one of the dominant loss mechanisms hindering performance. Whereas CT state dynamics following electron transfer from donor to acceptor have been widely studied, there is not much known about the dynamics of bound CT states produced by hole transfer from the acceptor to the donor. In this letter, we compare the dynamics of CT states formed in the different charge-transfer pathways in a range of model systems.

Stroke risk stratification scores in atrial fibrillation: current recommendations for clinical practice and future perspectives.

Atrial fibrillation (AF) increases the risk of stroke. This additional risk varies depending on the presence of various clinical risk factors. The contribution of some risk factors, for example vascular disease and female gender, has been disputed.

On the energetic dependence of charge separation in low-band-gap polymer/fullerene blends.

The energetic driving force required to drive charge separation across donor/acceptor heterojunctions is a key consideration for organic optoelectronic devices. Herein we report a series of transient absorption and photocurrent experiments as a function of excitation wavelength and temperature for two low-band-gap polymer/fullerene blends to study the mechanism of charge separation at the donor/acceptor interface. For the blend that exhibits the smallest donor/acceptor LUMO energy level offset, the photocurrent quantum yield falls as the photon excitation energy is reduced toward the band gap, but the yield of bound, interfacial charge transfer states rises.

Children with phenylketonuria treated early: basic audiological and electrophysiological evaluation.

Objectives: Individuals with phenylketonuria (PKU) can exhibit deficits in executive functions, intelligence, attention, visual-spatial processing abilities, and efficiency stemming presumably from deficient neurotransmitter synthesis, even when the disorder is diagnosed and treated early. Basic audiological and electrophysiological evaluations were used to examine the peripheral and central auditory pathways of children with early-treated PKU, who followed adequate versus inadequate diets. Results were compared with those of age-matched children without PKU.

Electron transfer in dye-sensitised semiconductors modified with molecular cobalt catalysts: photoreduction of aqueous protons.

A visible-light driven H(2) evolution system comprising of a Ru(II) dye (RuP) and Co(III) proton reduction catalysts (CoP) immobilised on TiO(2) nanoparticles and mesoporous films is presented. The heterogeneous system evolves H(2) efficiently during visible-light irradiation in a pH-neutral aqueous solution at 25 °C in the presence of a hole scavenger. Photodegradation of the self-assembled system occurs at the ligand framework of CoP, which can be readily repaired by addition of fresh ligand, resulting in turnover numbers above 300 mol H(2) (mol CoP)(-1) and above 200,000 mol H(2) (mol TiO(2) nanoparticles)(-1) in water.

Long-lived charge separated states in nanostructured semiconductor photoelectrodes for the production of solar fuels.

The efficient use of sunlight to drive the production of solar fuels requires the photogeneration of suitably long-lived charge separated states capable of driving the multi-electron chemistry of fuel synthesis. Here we discuss a range of promising material design approaches to increasing charge carrier lifetimes, focusing upon semiconductor photoelectrodes for water photolysis and carbon dioxide reduction. Parallels are drawn between the strategies deployed in the development of such artificial systems and those found in natural photosynthesis.

Acceleration effects of phosphate modification on the decay dynamics of photo-generated electrons of TiO2 and its photocatalytic activity.

The surface modification with a proper amount of phosphate accelerates the dynamic decay of photogenerated electrons in the nanocrystalline anatase TiO(2) film in the presence of O(2), consequently prolonging greatly the lifetime of photogenerated holes so as to improve the charge separation of TiO(2) and then its photocatalytic activity for degrading gas-phase acetaldehyde and liquid-phase phenol mainly based on the transient absorption spectra and the measurements of electrochemical O(2) reduction and the produced hydroxyl radical amount. The acceleration effects are attributed to the increased amount of adsorbed O(2) by means of the curves of O(2) temperature-programmed desorption.

Dynamics of photogenerated holes in surface modified α-Fe2O3 photoanodes for solar water splitting.

This paper addresses the origin of the decrease in the external electrical bias required for water photoelectrolysis with hematite photoanodes, observed following surface treatments of such electrodes. We consider two alternative surface modifications: a cobalt oxo/hydroxo-based (CoO(x)) overlayer, reported previously to function as an efficient water oxidation electrocatalyst, and a Ga(2)O(3) overlayer, reported to passivate hematite surface states. Transient absorption studies of these composite electrodes under applied bias showed that the cathodic shift of the photocurrent onset observed after each of the surface modifications is accompanied by a similar cathodic shift of the appearance of long-lived hematite photoholes, due to a retardation of electron/hole recombination.

Synthesis of novel thieno[3,2-b]thienobis(silolothiophene) based low bandgap polymers for organic photovoltaics.

Thieno[3,2-b]thienobis(silolothiophene), a new electron rich hexacyclic monomer has been synthesized and incorporated into three novel donor-acceptor low-bandgap polymers. By carefully choosing the acceptor co-monomer, the energy levels of the polymers could be modulated and high power conversion efficiencies of 5.52% were reached in OPV devices.

Insights from Transient Optoelectronic Analyses on the Open-Circuit Voltage of Organic Solar Cells.

In this Perspective, we review recent progress on the use of transient optoelectronic techniques to quantify the processes determining the open-circuit voltage (VOC) of organic solar cells. Most theoretical treatments of VOC include the effects of both material energetics and recombination dynamics, yet most experimental approaches are based on materials energetics alone. We show that by direct measurement of charge carrier dynamics and densities, the rate of nongeminate charge recombination may be determined within working cells and its impact on achievable VOC determined.

Enhanced photocatalytic activity of nc-TiO2 by promoting photogenerated electrons captured by the adsorbed oxygen.

Nanocrystalline TiO2 (nc-TiO2) was modified by a simple post treatment with monometallic sodium orthophosphate solution. It is shown that the surface modification with an appropriate amount of phosphate obviously enhances the surface photovoltage responses of nc-TiO2 in the presence of O2, clearly indicating that the separation of photogenerated charges is greatly improved by promoting the photoelectrons captured by the adsorbed O2. This is well responsible for its much high photocatalytic activity for degrading representative gas-phase acetaldehyde, liquid-phase phenol and rhodamine B of phosphate-modified nc-TiO2, compared with the unmodified nc-TiO2.