1-Methylcyclopropene Preharvest Application and Its Effect on Storability of ‘Comice’ and ‘Bosc’ Pears

Sprayable formulation of 1-methylcyclopropene (1-MCP) was tested as a preharvest application on European pears to determine the best timing and rate of 1-MCP application for maintaining fruit firmness and quality of trees during harvest and in storage after harvest. Two rates of 1-MCP, 0.06 and 0.13 g⋅L−1 active ingredient (a.i.) (minimum and maximum rates, respectively), were sprayed 1 week and 2 weeks before commercial harvest on two cultivars, Bosc and Comice, in 2017 and 2018. After 2 months in cold storage (0 ± 1 °C), differences in fruit firmness of both cultivars were observed among treatments. For ‘Bosc’, fruit treated with both rates 1 week before harvest were 50% firmer than nontreated control fruit. For ‘Comice’, fruit treated with the maximum rate both 2 weeks and 1 week before commercial harvest were 46% and 31% firmer than nontreated control fruit, respectively. However, after 4 months in storage, no differences in fruit firmness of both ‘Bosc’ and ‘Comice’ were observed among treatments. The sprayable 1-MCP application applied 2 weeks before commercial harvest also affected the fruit firmness on trees. The maximum rate of 1-MCP treatment consistently maintained the fruit firmness by 5.0 N compared with fruit treated with the minimum rate and nontreated controls. This effect was significant until 1 week after commercial harvest for both cultivars and until 2 weeks after commercial harvest for ‘Bosc’. The poststorage fruit firmness and overall eating quality of ‘Bosc’ were unaffected by the maximum rate of 1-MCP application as well as the extended harvest time. However, for ‘Comice’, the overall eating quality was negatively impacted by 1-MCP treatments. This study suggests that the maximum rate (0.13 g⋅L−1 a.i.) of 1-MCP application 2 weeks before commercial harvest maintains the fruit firmness of ‘Bosc’ for at least 2 weeks more and offers an extended harvest window for better preharvest management. Furthermore, this treatment improves the physiological fruit quality such as senescence scald during the poststorage period without significantly affecting the poststorage ripening of ‘Bosc’ after 4 months of storage.

Trailing-edge zombie forests can increase population persistence in the face of climate change

Climate-driven habitat shifts pose challenges for dispersal-limited, late-maturing taxa such as trees. Older trees are often the most reproductive individuals in the population, but as habitats shift, these individuals can be left behind in the trailing range edge, generating "zombie forests" that may persist long after the suitable habitat has shifted. Are these zombie forests vestiges of ecosystems past or do they play an ecological role? To understand how zombie forests affect population persistence, we developed a spatially explicit, stage-structured model of tree populations occupying a shifting habitat. Our model shows that seed dispersal from zombie forests to the range core can considerably increase the maximum rate of climate change that a population can withstand. Moreover, the entire core population can ultimately descend from recruitment-limited zombie forests, highlighting their demographic value. Our results suggest that preserving trailing-edge zombie forests can greatly increase population persistence in the face of climate change.

Enhanced Inertial Response Capability of a Variable Wind Energy Conversion System

An inertial response emulated control strategy of doubly-fed induction generators (DFIGs) is able to arrest their frequency decline following a severe frequency event. Nevertheless, the control coefficient is unchanged, so as to limit the benefit potentiality of improving the inertial response capability for various disturbances and provide less of a benefit for boosting the frequency nadir. This paper addresses an enhanced inertial response emulated control scheme for a DFIG to improve the maximum frequency deviation and maximum rate of change of frequency for various disturbances. To this end, the control coefficient is coupled with the system frequency deviation so as to regulate the control coefficient according to the system frequency deviation (i.e., sizes of the disturbance). Results clearly indicate that the proposed inertial response emulated control strategy provides better performance in terms of improving the maximum rate of change of frequency and maximum frequency deviation under various sizes of disturbance and random wind speed conditions.

E - Capacity - Equivocation Region of Wiretap Channel

One of the problems of information - theoretic security concerns secure communication over a wiretap channel. The aim in the general wiretap channel model is to maximize the rate of the reliable communication from the source to the legitimate receiver, while keeping the confidential information as secret as possible from the wiretapper (eavesdropper). We introduce and investigate the E - capacity - equivocation region and the E - secrecy capacity function for the wiretap channel, which are, correspondingly, the generalizations of the capacity - equivocation region and secrecy - capacity studied by Csiszár and Körner (1978). The E - capacity equivocation region is the closure of the set of all achievable rate - reliability and equivocation pairs, where the rate - reliability function represents the optimal dependence of rate on the error probability exponent (reliability). By analogy with the notion of E - capacity, we consider the E - secrecy capacity function that for the given E is the maximum rate at which the message can be transmitted being kept perfectly secret from the wiretapper.

Carbon Flux in the Temperate Zooxanthellate Sea Anemone Anthopleura aureoradiata

<p>This study investigated the algal density and growth, photophysiology and contribution of algae to animal respiration requirements (CZAR), in the symbiosis between the sea anemone Anthopleura aureoradiata and its dinoflagellate symbionts (zooxanthellae) under field and laboratory conditions. A. aureoradiata was collected during summer and winter on sunny and cloudy days from a rocky shore and mudflat environment. Algal densities displayed a trend of being 2.6 and 1.7 times greater during summer than winter on the mudflat on a sunny and cloudy day respectively. Algal division was asynchronous under field conditions over a daily period, and was 2.1 and 1.3 times greater on the rocky shore and mudflat respectively, during winter than summer on sunny days. Under field conditions, the efficiency and maximum rate of photosynthesis (per cell and per association) as well as respiration rate, were all greater during summer than winter. Cloud cover resulted in a difference in a higher maximum rate of photosynthesis per cell on a sunny day than a cloudy day within summer at Kau Bay. Additionally, these photosynthetic parameters and respiration rate were all greater on the rocky shore than mudflat while the photosynthetic compensation irradiance was greater on the mudflat. The CZAR was greatest on the rocky shore during summer on a sunny day (151%) and was also > 100% on a cloudy day in summer at this same site (129%); on the mudflat the CZAR was greatest during summer on a sunny day (89%). The CZAR was measured to be zero during winter at both sites during winter on cloudy days. Additionally, under laboratory conditions A. aureoradiata was exposed to gradual (GTC) and rapid (RTC) temperature changes. While under GTC and RTC, the algal density did not vary, though higher temperatures led to an increase in algal division. Under both GTC and RTC, the photosynthetic efficiency, maximum photosynthetic rate (per cell and per association) and respiration rate all increased with temperature, however under GTC these parameters all decreased between 32.5 [degrees]C and 35 [degrees] C. Photosynthetic compensation irradiance increased with temperature under both GTC and RTC until 30 [degrees] C, after which respiration exceeded maximum photosynthesis, meaning that photosynthetic compensation did not occur. Furthermore, photosynthetic saturation irradiance increased with temperature and peaked at 15 [degrees] C before declining with temperature under both GTC and RTC. The CZAR under GTC increased with temperature until it peaked at 15 [degrees] C (128%), before decreasing to zero at 30 [degrees] C - 35 [degrees] C. Under RTC, the CZAR was zero for all temperatures except at 10 [degrees] C where it was 25.1%. A CZAR < 100% may suggest that the symbiosis between A. aureoradiata and its zooxanthellae is parasitic under most conditions and at most times of the year. Alternatively, there may be some benefit to the symbiosis due to a competitive advantage over other macro-invertebrate species as a result of carbon translocation from the symbiont providing extra support for reproduction and growth. This study also showed A. aureoradiata to have a wide temperature tolerance reflecting the fluctuating conditions of a variable temperate environment. The wide temperature tolerance of this species suggests that it will tolerate short term (50 - 100 years) increases in ocean temperatures however, the threat beyond this time frame with other factors such as ocean acidification remains to be determined.</p>

Carbon Flux in the Temperate Zooxanthellate Sea Anemone Anthopleura aureoradiata

<p>This study investigated the algal density and growth, photophysiology and contribution of algae to animal respiration requirements (CZAR), in the symbiosis between the sea anemone Anthopleura aureoradiata and its dinoflagellate symbionts (zooxanthellae) under field and laboratory conditions. A. aureoradiata was collected during summer and winter on sunny and cloudy days from a rocky shore and mudflat environment. Algal densities displayed a trend of being 2.6 and 1.7 times greater during summer than winter on the mudflat on a sunny and cloudy day respectively. Algal division was asynchronous under field conditions over a daily period, and was 2.1 and 1.3 times greater on the rocky shore and mudflat respectively, during winter than summer on sunny days. Under field conditions, the efficiency and maximum rate of photosynthesis (per cell and per association) as well as respiration rate, were all greater during summer than winter. Cloud cover resulted in a difference in a higher maximum rate of photosynthesis per cell on a sunny day than a cloudy day within summer at Kau Bay. Additionally, these photosynthetic parameters and respiration rate were all greater on the rocky shore than mudflat while the photosynthetic compensation irradiance was greater on the mudflat. The CZAR was greatest on the rocky shore during summer on a sunny day (151%) and was also > 100% on a cloudy day in summer at this same site (129%); on the mudflat the CZAR was greatest during summer on a sunny day (89%). The CZAR was measured to be zero during winter at both sites during winter on cloudy days. Additionally, under laboratory conditions A. aureoradiata was exposed to gradual (GTC) and rapid (RTC) temperature changes. While under GTC and RTC, the algal density did not vary, though higher temperatures led to an increase in algal division. Under both GTC and RTC, the photosynthetic efficiency, maximum photosynthetic rate (per cell and per association) and respiration rate all increased with temperature, however under GTC these parameters all decreased between 32.5 [degrees]C and 35 [degrees] C. Photosynthetic compensation irradiance increased with temperature under both GTC and RTC until 30 [degrees] C, after which respiration exceeded maximum photosynthesis, meaning that photosynthetic compensation did not occur. Furthermore, photosynthetic saturation irradiance increased with temperature and peaked at 15 [degrees] C before declining with temperature under both GTC and RTC. The CZAR under GTC increased with temperature until it peaked at 15 [degrees] C (128%), before decreasing to zero at 30 [degrees] C - 35 [degrees] C. Under RTC, the CZAR was zero for all temperatures except at 10 [degrees] C where it was 25.1%. A CZAR < 100% may suggest that the symbiosis between A. aureoradiata and its zooxanthellae is parasitic under most conditions and at most times of the year. Alternatively, there may be some benefit to the symbiosis due to a competitive advantage over other macro-invertebrate species as a result of carbon translocation from the symbiont providing extra support for reproduction and growth. This study also showed A. aureoradiata to have a wide temperature tolerance reflecting the fluctuating conditions of a variable temperate environment. The wide temperature tolerance of this species suggests that it will tolerate short term (50 - 100 years) increases in ocean temperatures however, the threat beyond this time frame with other factors such as ocean acidification remains to be determined.</p>

Best Conditions for the Production of Natural Isopentyl Acetate (Banana Aroma) from Cheese Industry Waste: An Experimental Precursor Approach

In some fermentation systems, whey components (lactose, proteins and minerals) can produce isopentyl acetate (IA). An analysis of the best conditions for IA production with Kluyveromyces marxianus was developed in this work. The experiment design was two-factor and three-level design based on a response surface methodology (RSM) using Design-Expert® software. The analysis of anomeric protons by nuclear magnetic resonance (1H-NMR) showed 81.25% of β lactose content. This characteristic favored the production of IA. The maximum output (Mp) of IA, determined by gas chromatography, was 9.52 g/L (p < 0.05). The central composite design (CCD) was used to perform the factor analysis. Results showed that concentrations of 0.03 (g/L) ammonium sulphate and 0.3 (v/v) of isoamyl alcohol are the best conditions for a maximum rate of IA production. The production of IA can reduce the discharge of whey, allowing its reuse and revaluation.

Rapid estimation of photosynthetic leaf traits of tropical plants in diverse environmental conditions using reflectance spectroscopy

Tropical forests are one of the main carbon sinks on Earth, but the magnitude of CO2 absorbed by tropical vegetation remains uncertain. Terrestrial biosphere models (TBMs) are commonly used to estimate the CO2 absorbed by forests, but their performance is highly sensitive to the parameterization of processes that control leaf-level CO2 exchange. Direct measurements of leaf respiratory and photosynthetic traits that determine vegetation CO2 fluxes are critical, but traditional approaches are time-consuming. Reflectance spectroscopy can be a viable alternative for the estimation of these traits and, because data collection is markedly quicker than traditional gas exchange, the approach can enable the rapid assembly of large datasets. However, the application of spectroscopy to estimate photosynthetic traits across a wide range of tropical species, leaf ages and light environments has not been extensively studied. Here, we used leaf reflectance spectroscopy together with partial least-squares regression (PLSR) modeling to estimate leaf respiration (Rdark25), the maximum rate of carboxylation by the enzyme Rubisco (Vcmax25), the maximum rate of electron transport (Jmax25), and the triose phosphate utilization rate (Tp25), all normalized to 25°C. We collected data from three tropical forest sites and included leaves from fifty-three species sampled at different leaf phenological stages and different leaf light environments. Our resulting spectra-trait models validated on randomly sampled data showed good predictive performance for Vcmax25, Jmax25, Tp25 and Rdark25 (RMSE of 13, 20, 1.5 and 0.3 μmol m-2 s-1, and R2 of 0.74, 0.73, 0.64 and 0.58, respectively). The models showed similar performance when applied to leaves of species not included in the training dataset, illustrating that the approach is robust for capturing the main axes of trait variation in tropical species. We discuss the utility of the spectra-trait and traditional gas exchange approaches for enhancing tropical plant trait studies and improving the parameterization of TBMs.

Fabrication of g-C3N4 Nanosheets Anchored With Controllable CdS Nanoparticles for Enhanced Visible-Light Photocatalytic Performance

Herein, g-C3N4/CdS hybrids with controllable CdS nanoparticles anchoring on g-C3N4 nanosheets were constructed. The effects of CdS nanoparticles on photocatalytic H2 production and organic molecule degradation for g-C3N4/CdS hybrids were investigated. The maximum rate of H2 production for g-C3N4/CdS sample was 1,070.9 μmol g−1 h−1, which was about four times higher than that of the individual g-C3N4 nanosheet sample. The enhanced photocatalytic performance for prepared hybrids could be mainly attributed to the following causes: the formed heterojunctions can contribute to the light absorption and separation of photogenerated electrons and holes, the two-dimensional layered structure facilitates the transmission and transfer of electrons, and high specific surface area could provide more exposed active sites.