The ability to upconvert two low energy photons into one high energy photon has potential applications in solar energy, biological imaging, and data storage. In this Letter, CdSe and PbSe semiconductor nanocrystals are combined with molecular emitters (diphenylanthracene and rubrene) to upconvert photons in both the visible and the near-infrared spectral regions. Absorption of low energy photons by the nanocrystals is followed by energy transfer to the molecular triplet states, which then undergo triplet-triplet annihilation to create high energy singlet states that emit upconverted light. By using conjugated organic ligands on the CdSe nanocrystals to form an energy cascade, the upconversion process could be enhanced by up to 3 orders of magnitude. The use of different combinations of nanocrystals and emitters shows that this platform has great flexibility in the choice of both excitation and emission wavelengths.

At present, there is a reasonable understanding of the independent effects of catch-and-release (C&R) angling stressors, such as air exposure and water temperature, on endpoints such as physiological disturbance, behavioural impairment and mortality. However, little is known about the multiplicative or interactive nature of these different C&R stressors. This study used bluegill (Lepomis macrochirus) as a model to evaluate the combined effects of water temperature and air exposure on fish behaviour, equilibrium status and short-term mortality following C&R. Experiments were replicated over 3 days with different ambient water temperatures (18.3, 22.8 and 27.4 • C). On each day, fish were captured by standard angling techniques, exposed to a range of air exposure durations (0, 30, 60, 120, 240, 480 and 960 s), and subsequently monitored for behavioural changes (within the first 300 s) and short-term (48 h) delayed mortality. Additional fish were captured by seine net for use as controls. There was an interactive effect of temperature and air exposure, whereby fish exposed to the highest temperature and longer air exposure durations lost equilibrium more often and had depressed ventilation rates relative to fish exposed to minimal air exposure and the lowest temperature. Immediate mortality at the lowest temperatures was negligible. However, significant delayed mortality (up to 80%) was noted at the highest water temperature (27.4 • C) in fish exposed to the three longest air exposure groups. In addition, at 27.4 • C, mortality among fish exposed to 480 and 960 s occurred at a faster rate than in any other treatment group. These results indicate that at low to moderate water temperatures, extended air exposure for bluegill may result in little mortality. However, at high water temperatures, short-term mortality (within 48 h) can be substantial, especially for fish that experience extended air exposure durations. Anglers and managers must recognize that C&R stressors can interact to have more dire consequences than when applied independently.

Two-photon fluorescence lifetime imaging is used to identify microdomains (1-25 microm) of two distinct pH values within the uppermost layer of the epidermis (stratum corneum). The fluorophore used is 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF), whose lifetime tau (pH 4.5, tau = 2.75 ns; pH 8.5, tau = 3.90 ns) is pH dependent over the pH range of the stratum corneum (pH 4.5 to pH 7.2). Hairless mice (SKH1-hrBR) are used as a model for human skin. Images (< or =50 microm x 50 microm) are acquired every 1.7 microm from the stratum corneum surface to the first viable layer (stratum granulosum). Acidic microdomains (average pH 6.0) of variable size (~1 microm in diameter with variable length) are detected within the extracellular matrix of the stratum corneum, whereas the intracellular space of the corneocytes in mid-stratum corneum (25 microm diameter) approaches neutrality (average pH 7.0). The surface is acidic. The average pH of the stratum corneum increases with depth because of a decrease in the ratio of acidic to neutral regions within the stratum corneum. The data definitively show that the stratum corneum acid mantle results from the presence of aqueous acidic pockets within the lipid-rich extracellular matrix.

Over the past 20 years, there has been a dramatic increase in the use of physiological tools and experimental approaches for the study of the biological consequences of catch‐and‐release angling practices for fishes. Beyond simply documenting problems, physiological data are also being used to test and refine different strategies for handling fish such that stress is minimised and survival probability maximised, and in some cases, even for assessing and facilitating recovery post‐release. The inherent sensitivity of physiological processes means that nearly every study conducted has found some level of – unavoidable – physiological disturbance arising from recreational capture and subsequent release. An underlying tenet of catch‐and‐release studies that incorporate physiological tools is that a link exists between physiological status and fitness. In reality, finding such relationships has been elusive, with further extensions of individual‐level impacts to fish populations even more dubious. A focus of this article is to describe some of the challenges related to experimental design and interpretation that arise when using physiological tools for the study of the biological consequences of catch‐and‐release angling. Means of overcoming these challenges and the extrapolation of physiological data from individuals to the population level are discussed. The argument is presented that even if it is difficult to demonstrate strong links to mortality or other fitness measures, let alone population‐level impacts of catch‐and‐release, there remains merit in using physiological tools as objective indicators of fish welfare, which is an increasing concern in recreational fisheries. The overarching objective of this paper is to provide a balanced critique of the use of physiological approaches in catch‐and‐release science and of their role in providing meaningful information for anglers and managers.

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