Composite Indium Tin Oxide Nanofibers with Embedded Hematite Nanoparticles for Photoelectrochemical Water Splitting.

Hematite is a classical photoanode material for photoelectrochemical water splitting due to its stability, performance, and low cost. However, the effect of particle size is still a question due to the charge transfer to the electrodes. In this work, we addressed this subject by the fabrication of a photoelectrode with hematite nanoparticles embedded in close contact with the electrode substrate. The nanoparticles were synthesized by a solvothermal method and colloidal stabilization with charged hydroxide molecules, and we were able to further use them to prepare electrodes for water photo-oxidation. Hematite nanoparticles were embedded within electrospun tin-doped indium oxide nanofibers. The fibrous layer acted as a current collector scaffold for the nanoparticles, supporting the effective transport of charge carriers. This method allows better contact of the nanoparticles with the substrate, and also, the fibrous scaffold increases the optical density of the photoelectrode. Electrodes based on nanofibers with embedded nanoparticles display significantly enhanced photoelectrochemical performance compared to their flat nanoparticle-based layer counterparts. This nanofiber architecture increases the photocurrent density and photon-to-current internal conversion efficiency by factors of 2 and 10, respectively.

Extraction of mobile charge carrier photogeneration yield spectrum of ultrathin-film metal oxide photoanodes for solar water splitting.

Light absorption in strongly correlated electron materials can excite electrons and holes into a variety of different states. Some of these excitations yield mobile charge carriers, whereas others result in localized states that cannot contribute to photocurrent. The photogeneration yield spectrum, ξ(λ), represents the wavelength-dependent ratio between the contributing absorption that ultimately generates mobile charge carriers and the overall absorption. Despite being a vital material property, it is not trivial to characterize. Here, we present an empirical method to extract ξ(λ) through optical and external quantum efficiency measurements of ultrathin films. We applied this method to haematite photoanodes for water photo-oxidation, and observed that it is self-consistent for different illumination conditions and applied potentials. We found agreement between the extracted ξ(λ) spectrum and the photoconductivity spectrum measured by time-resolved microwave conductivity. These measurements revealed that mobile charge carrier generation increases with increasing energy across haematite's absorption spectrum. Low-energy non-contributing absorption fundamentally limits the photoconversion efficiency of haematite photoanodes and provides an upper limit to the achievable photocurrent that is substantially lower than that predicted based solely on absorption above the bandgap. We extended our analysis to TiO2 and BiVO4 photoanodes, demonstrating the broader utility of the method for determining ξ(λ).

Operando X-ray Absorption Spectroscopy (XAS) Observation of Photoinduced Oxidation in FeNi (Oxy)hydroxide Overlayers on Hematite (α-Fe2O3) Photoanodes for Solar Water Splitting.

An FeNi (oxy)hydroxide cocatalyst overlayer was photoelectrochemically deposited on a thin-film hematite (α-Fe2O3) photoanode, leading to a cathodic shift of ∼100 mV in the photocurrent onset potential. Operando X-ray absorption spectroscopy (XAS) at the Fe and Ni K-edges was used to study the changes in the overlayer with potential in the dark and under illumination conditions. Potential or illumination only had a minor effect on the Fe oxidation state, suggesting that Fe atoms do not accumulate significant amount of charge over the whole potential range. In contrast, the Ni K-edge spectra showed pronounced dependence on potential in the dark and under illumination. The effect of illumination is to shift the onset for the Ni oxidation because of the generated photovoltage and suggests that holes that are photogenerated in hematite are transferred mainly to the Ni atoms in the overlayer. The increase in the oxidation state of Ni proceeds at potentials corresponding to the redox wave of Ni, which occurs immediately prior to the onset of the oxygen evolution reaction (OER). Linear combination fitting analysis of the obtained spectra suggests that the overlayer does not have to be fully oxidized to promote oxygen evolution. Cathodic discharge measurements show that the photogenerated charge is stored almost exclusively in the Ni atoms within the volume of the overlayer.

The "Rust" Challenge: On the Correlations between Electronic Structure, Excited State Dynamics, and Photoelectrochemical Performance of Hematite Photoanodes for Solar Water Splitting.

In recent years, hematite's potential as a photoanode material for solar hydrogen production has ignited a renewed interest in its physical and interfacial properties, which continues to be an active field of research. Research on hematite photoanodes provides new insights on the correlations between electronic structure, transport properties, excited state dynamics, and charge transfer phenomena, and expands our knowledge on solar cell materials into correlated electron systems. This research news article presents a snapshot of selected theoretical and experimental developments linking the electronic structure to the photoelectrochemical performance, with particular focus on optoelectronic properties and charge carrier dynamics.

Inelastic X-ray scattering with 0.75 meV resolution at 25.7 keV using a temperature-gradient analyzer.

The use of temperature-gradient analyzers for non-resonant high-resolution inelastic X-ray scattering is investigated. The gradient compensates for geometrical broadening of the energy resolution by adjusting the lattice spacing of the analyzer crystal. Applying a ∼ 12 mK temperature gradient across a 9.5 cm analyzer, resolutions of 0.75 (2) meV FWHM at 25.7 keV for Si(13 13 13) and 1.25(2) meV at 21.7 keV for Si(11 11 11) were measured, while retaining large (250 mm) clearance between the sample position and detector, and reasonable (9.3 mrad × 8.8 mrad) analyzer acceptance. The temperature control and stability are discussed.

Helicobacter hypothesis for idiopathic parkinsonism: before and beyond.

We challenge the concept of idiopathic parkinsonism (IP) as inevitably progressive neurodegeneration, proposing a natural history of sequential microbial insults with predisposing host response. Proof-of-principle that infection can contribute to IP was provided by case studies and a placebo-controlled efficacy study of Helicobacter eradication. "Malignant" IP appears converted to "benign", but marked deterioration accompanies failure. Similar benefit on brady/hypokinesia from eradicating "low-density" infection favors autoimmunity. Although a minority of UK probands are urea breath test positive for Helicobacter, the predicted probability of having the parkinsonian label depends on the serum H. pylori antibody profile, with clinically relevant gradients between this "discriminant index" and disease burden and progression. In IP, H. pylori antibodies discriminate for persistently abnormal bowel function, and specific abnormal duodenal enterocyte mitochondrial morphology is described in relation to H. pylori infection. Slow intestinal transit manifests as constipation from the prodrome. Diarrhea may flag secondary small-intestinal bacterial overgrowth. This, coupled with genetically determined intense inflammatory response, might explain evolution from brady/hypokinetic to rigidity-predominant parkinsonism.

Cryoablation as primary treatment for localized prostate cancer followed by penile rehabilitation.

OBJECTIVES: To determine the medium term efficacy and morbidity of patients who underwent cryoablation as primary therapy for localized prostate cancer followed by a penile rehabilitation regimen. METHODS: Patients were treated with whole gland cryoablation. Those potent at intervention were encouraged to use a vacuum erection device regularly after treatment. Incontinence was defined as any leakage of urine. Potency was defined as the ability to achieve an erection sufficient to complete intercourse with or without oral pharmaceutical agents. Biochemical failure was defined as three successive rises in prostate-specific antigen, with a final value greater than 1.0 ng/mL. RESULTS: A total of 416 consecutive patients were treated. The mean patient age was 69.4 years, mean prostate-specific antigen level was 8.7 ng/mL, median Gleason score was 6, and median stage was T1c. The mean follow-up of the entire population was 20.4 +/- 14.7 months. Of those continent before treatment, 4.0% were incontinent at 6 months but only 2 (0.6%) used any absorbent pads. Kaplan-Meier analysis demonstrated progressive recovery of sexual function of preoperatively potent men, with 41.4% +/- 4.3% and 51.3% +/- 5.9% potent 1 and 4 years after treatment, respectively. No patients had rectal fistula. The actuarial probability of remaining biochemically disease free at 4 years was 79.6% +/- 2.4%, with a mean time to failure of 4.2 months. After therapy, 168 patients underwent biopsy; 17 had positive findings (10.1%). The positive biopsy rate for the entire population was 4.1% (17 of 416). CONCLUSIONS: The results of our study have indicated that cryoablation as a primary treatment of localized prostate cancer is effective with acceptable morbidity. The use of a penile rehabilitation regimen after treatment appeared to substantially increase postcryoablation potency.

Focal cryosurgery followed by penile rehabilitation as primary treatment for localized prostate cancer: initial results.

The study reported here was undertaken to assess medium short-term efficacy of focal cryoablation as primary therapy for localized prostate cancer and to determine the rate of morbidity in patients who undergo this treatment. Patients were treated with focal cryoablation with argon cryoprobes under ultrasonographic visualization with temperature monitoring. Men who were potent at the time of intervention were encouraged to use a vacuum erectile dysfunction device on a regular basis after treatment. Incontinence was defined as any urine leakage regardless of the number of pads worn (if any). Potency was defined as the ability to achieve an erection sufficient to complete intercourse with or without oral pharmaceuticals. Biochemical failure was defined as 3 successive rises in serum prostate-specific antigen (PSA) concentration. A total of 60 consecutive patients were treated. Mean patient age was 69.0 years; mean PSA was 7.2 ng/mL, median Gleason score was 6, and median stage was T1c. Before treatment was initiated, all patients were continent and 72.7% were potent. Mean follow-up for the entire population was 15.2+/-7.4 months. Of those patients who were continent before receiving treatment, 3.6% were incontinent at 6 months, but none used any absorbent pads. At last follow-up, 80.4% of patients were biochemically disease free; mean time to failure was 3.5 months among those for whom treatment failed. The positive biopsy rate after first treatment was 23.3%, and mean time to failure was 12.0 months. Of those who underwent a second focal cryoablation procedure after positive biopsy, 66% were subsequently cancer free. All patients who were potent after the first cryoablation procedure regained their potency after the second cryoablation procedure. Focal cryoablation combined with penile rehabilitation as primary treatment for localized prostate cancer is a minimally morbid procedure with acceptable morbidity and the potential for retreatment of a patient if cancer is subsequently detected. Further study is warranted.

Cryosurgery as primary treatment for localized prostate cancer: a community hospital experience.

The technique and recent experience incorporating cryosurgery into our community practice for primary treatment of localized prostate cancer is described. Between December 2000 and December 2001, a total of 93 patients underwent targeted cryoablation for localized prostate cancer. Of the 93 patients, 18 had failed radiotherapy, and cryotherapy was used as salvage therapy. The remaining 75 patients underwent targeted cryoablation of the prostate as primary therapy. A single urologist using an argon-based cryoablation system performed the procedure. Cryoprobes and thermosensors were placed under transrectal ultrasound guidance via a transperineal route. A double freeze-thaw cycle was used with anterior-to- posterior probe operation. Strategically placed thermosensors were used to monitor and control the freezing, and a warming catheter was used to protect the urethra. We achieved a nadir prostate-specific antigen level of < or =0.4 ng/mL in 84% of the entire population we studied (63 of 75 patients). Postsurgery complications were minimal. Incontinence developed in 4 patients, as did postsuprapubic catheter removal urinary retention. Erectile dysfunction developed in 28 of 34 patients who were potent preoperatively, with 6 of the 34 patients regaining potency after surgery. No rectourethral fistula formation occurred. Urethral sloughing was observed in 5 patients, 1 of whom developed a scrotal abscess during treatment of the sloughing. The use of cryoablation of the prostate for the treatment of localized adenocarcinoma of the prostate is feasible and can easily be transferred from the pioneering centers to the community hospitals without sacrificing safety or efficacy.