Potential and pitfalls: On the use of transient absorption spectroscopy for in situ and operando studies of photoelectrodes.

Here, we discuss the application, advantages, and potential pitfalls of using transient UV/Vis (ultraviolet-visible) absorption spectroscopy to study photoelectrodes for water splitting. We revisit one of the most commonly studied water oxidation photoanodes (α-Fe2O3-x) to provide commentary and guidelines on experiment design and data analysis for transient absorption (TA) studies of photoelectrodes within a photoelectrochemical cell. We also assess the applicability of such in situ TA studies to understand photoelectrodes under operating conditions. A major limitation is that most, if not all, past in situ TA studies have been carried out using only pulsed light sources to generate carriers, with the electrode held in the dark at other times, which is shown to be a poor model for operating conditions. However, with a simple modification of existing TA experiments, a simple operando TA measurement is reported.

Energy conserving thermoregulatory patterns and lower disease severity in a bat resistant to the impacts of white-nose syndrome.

The devastating bat fungal disease, white-nose syndrome (WNS), does not appear to affect all species equally. To experimentally determine susceptibility differences between species, we exposed hibernating naïve little brown myotis (Myotis lucifugus) and big brown bats (Eptesicus fuscus) to the fungus that causes WNS, Pseudogymnoascus destructans (Pd). After hibernating under identical conditions, Pd lesions were significantly more prevalent and more severe in little brown myotis. This species difference in pathology correlates with susceptibility to WNS in the wild and suggests that survival is related to different host physiological responses. We observed another fungal infection, associated with neutrophilic inflammation, that was equally present in all bats. This suggests that both species are capable of generating a response to cold tolerant fungi and that Pd may have evolved mechanisms for evading host responses that are effective in at least some bat species. These host-pathogen interactions are likely mediated not just by host physiological responses, but also by host behavior. Pd-exposed big brown bats, the less affected species, spent more time in torpor than did control animals, while little brown myotis did not exhibit this change. This differential thermoregulatory response to Pd infection by big brown bat hosts may allow for a more effective (or less pathological) immune response to tissue invasion.

Host, pathogen, and environmental characteristics predict white-nose syndrome mortality in captive little brown myotis (Myotis lucifugus).

An estimated 5.7 million or more bats died in North America between 2006 and 2012 due to infection with the fungus Pseudogymnoascus destructans (Pd) that causes white-nose syndrome (WNS) during hibernation. The behavioral and physiological changes associated with hibernation leave bats vulnerable to WNS, but the persistence of bats within the contaminated regions of North America suggests that survival might vary predictably among individuals or in relation to environmental conditions. To investigate variables influencing WNS mortality, we conducted a captive study of 147 little brown myotis (Myotis lucifugus) inoculated with 0, 500, 5000, 50,000, or 500,000 Pd conidia and hibernated for five months at either 4 or 10°C. We found that female bats were significantly more likely to survive hibernation, as were bats hibernated at 4°C, and bats with greater body condition at the start of hibernation. Although all bats inoculated with Pd exhibited shorter torpor bouts compared to controls, a characteristic of WNS, only bats inoculated with 500 conidia had significantly lower survival odds compared to controls. These data show that host and environmental characteristics are significant predictors of WNS mortality, and that exposure to up to 500 conidia is sufficient to cause a fatal infection. These results also illustrate a need to quantify dynamics of Pd exposure in free-ranging bats, as dynamics of WNS produced in captive studies inoculating bats with several hundred thousand conidia may differ from those in the wild.

Configurationally rigid pentaorganosilicates.

The intramolecular substituent interchange in recently reported pentaorganosilicates is investigated by B3LYP calculations, which show excellent agreement with the experimental thermochemical data. Two types of ligand permutation are discerned (A and B), which both lead to racemization of the helical, spirocyclic anions. IRC calculations show that stereomutation A bifurcates into two enantiomeric reaction paths, which are inhibited by ortho substitution of the bidentate ligands. The other pathway (B) proceeds through a trigonal bipyramidal transition state with one bisequatorial bidentate ligand and is disfavored by increasing the pi-electron density of the ligand. A more electronegative fifth, monodentate substituent increases the barrier of pathway A and lowers that of pathway B, as in bis(biphenyl-2,2'-diyl)fluorosilicate, which is the first tetraorganofluorosilicate to be isolated and fully characterized. These concepts enabled us to design and synthesize methyl- and ethylbis([2]naphthylpyrrol-2,1'-diyl)silicate as Si-chiral pentaorganosilicates that are configurationally rigid at room temperature.

Handedness and sexual preference: a re-analysis of data presented by Rosenstein and Bigler.

Rosenstein and Bigler reported in 1987 that sexual orientation (exclusively versus nonexclusively heterosexual) was not related to right- versus nonright-handedness. However, re-analysis of their published data indicated that nonexclusive heterosexuals were 3.13 times more likely to be nonright-handed than were exclusively heterosexual subjects (p < .03).

Length of retrograde amnesia after head injury: a revised formula.

Our earlier retrospective study presented a formula relating lengths of retrograde amnesia to length of post-traumatic amnesia (PTA) and length of time since injury (Crovitz, Horn and Daniel, 1983). The earlier study derived the formula from 27 cases with retrograde amnesia. The present study adds another 75 cases, and we discuss similarities and differences between the two samples.

Neuropsychological aspects of disorientation.

Patients were asked twelve orientation questions before ECT and during the recovery period (the postictal confusional state) following ECT. Disorientation was more severe in the elderly. The different orientation items did not recover simultaneously; different recovery times may enable patients to give responses that are logical contradictions. While certain models (e.g., "person" versus "place" versus "time") may be useful in describing the differential recovery of orientation items, other models based on memory will probably prove more useful in delineating what causes this differential recovery. Patients gave responses to age and current year that were displaced backwards in years from the correct response. It is suggested that this displacement represents retrograde amnesia. As the postictal confusional state cleared, however, these backwardly displaced responses decreased in years of remoteness, thus showing a pattern of "shrinkage" that is similar to shrinking retrograde amnesia following head-injury. It is suggested that this result supports Ribot's law of regression.

Perceptual learning with right unilateral versus bilateral electroconvulsive therapy.

Perceptual learning was examined with respect to variations in ECT electrode placement (bilateral versus right unilateral) and ECT stimulus waveform (sinusoidal versus brief-pulse). While patients receiving right unilateral ECT demonstrated more perceptual learning than did those receiving bilateral ECT, no difference in perceptual learning resulted from the variation in electrical stimulus waveform. Furthermore, the amount of perceptual learning was unaffected by EEG seizure duration and by the total amount of electrical stimulus energy delivered. The theoretical issue of whether an electrical or a seizure difference between bilateral and right unilateral ECT is responsible for inter-group learning or memory differences is discussed, as well as practical issues related to the choice of electrode placement.

Everyday forgetting experiences: real-time investigations with implications for the study of memory management in brain-damaged patients.

In order to attempt to measure everyday forgetting experiences outside the laboratory, groups of undergraduates, healthy old people, and neuropathological patients with memory complaints were asked to use portable memory diaries. For a period of 7 days, they were immediately to write down every instance of noticing that they had forgotten anything. Types of forgetting, their frequency, and types of cues in the world that served as reminders that forgetting had occurred are discussed.