Thermal Energy Dissipation Research Articles

Crack paths in multiaxial fatigue of C45 steel specimens and correlation of lifetime with the thermal energy dissipation

The work reports the observed fatigue damage of C45 steel specimens tested in a previous work under multiaxial loading conditions and its relationship with the thermal energy dissipation which has been used in the last decades to estimate the uniaxial fatigue behavior of metals. For this purpose, fatigue data relevant to thin-walled samples made of quenched and tempered C45 steel tested under completely reversed combined axial and torsional cyclic loadings with different biaxiality ratios and phase-shift angles have been analysed. The analyses of crack paths at the initiation point of failure were performed after a 50% stiffness loss that corresponded to a crack size ranging from 7 to 15 mm; afterwards, the characteristic crack paths of each loading condition were analysed by using a digital microscope to identify the orientation of the crack initiation plane. After having broken all fatigue tested specimens under static tensile loading, the fracture surfaces were inspected close to the crack initiation point using a digital microscope. Despite the stress states and fatigue damage mechanisms dependent on the load condition, the Q parameter applied to the present experimental results proved to correlate all multiaxial fatigue test results in a single fatigue scatter band.

Layer-by-layer self-assembled functional coatings of carbon nanotube-polyethylenimine for enhanced heat transfer of heat sinks

Multi-functional porous coatings are promising candidates to improve overall heat transfer performances of heat sinks that are essential for thermal management of various electronic devices and mobility platforms. However, owing to the intrinsic limitations of the heat sinks comprising of the high-aspect-ratio fin-like structures, fabricating functional coatings involves complex process which incurs high-cost and long-time process. Herein, we report tunable and scalable layer-by-layer (LbL) self-assembly of multi-walled carbon nanotube (MWCNT)-polyethyleneimine (PEI) coatings on aluminum heat sinks for enhanced transient and static heat transfer performances. The repetitive immersing and rinsing of the negatively and positively charged solutions with carboxylic group-functionalized MWCNTs and PEI led to the electrostatic deposition of the LbL self-assembled MWCNT-PEI coatings on the aluminum heat sinks. All LbL coatings (50–250 nm in thickness) employing the fiber-like percolation networks of MWCNT-PEI could induce the morphological transition like the increased surface roughness while the black-like surface from carbon elements might provide the increased emissivity for the aluminum heat sinks. The multifunctional characteristics of the MWCNT-PEI coatings reinforced active surface area, fluid mixing and surface emissivity of the bare heat sink, thereby achieving the enhanced heat transfer coefficient (∼19%) and thermal resistance (16%). The optimal design of the porous coatings according to variation in applied thermal energy was elucidated by the comparable analysis between 10, 20, and 30 bilayers of the LbL MWCNT-PEI coatings. The developed LbL coatings can pave the way for effectively mitigating thermal shock or overload in transient and static operating conditions for a wide range of applications involving thermal energy dissipation.

Microstructure dependent ablation behaviour of precursor derived SiOC ceramic foam for high temperature applications

Ablation behaviour of poly(hydridomethylsiloxane) derived open and closed porous structured SiOC ceramic foams was evaluated using oxy-acetylene flame at 1500 °C for various time durations. X-ray diffraction and scanning electron microscopy analyses of ablated SiOC ceramic foams revealed the formation of a thin protective SiO2 layer inhibiting further oxidation. The closed porous structured SiOC ceramic foams exhibited very low mass ablation rate in contrast to open porous structured SiOC ceramic foams owing to the differences in thermal energy dissipation mechanism. The feasibility of the plausible foam reduction reactions pertaining to the ablation mechanism was further investigated by computing the Gibbs energy and HR-TEM analysis. The study corroborated the significance of tailoring the microporous structured SiOC ceramic foams as potential thermal protection material for high temperature applications.

Adaptive Responses of Citrusgrandis Leaves to Copper Toxicity Revealed by RNA-Seq and Physiology.

Copper (Cu)-toxic effects on Citrus grandis growth and Cu uptake, as well as gene expression and physiological parameters in leaves were investigated. Using RNA-Seq, 715 upregulated and 573 downregulated genes were identified in leaves of C. grandis seedlings exposed to Cu-toxicity (LCGSEC). Cu-toxicity altered the expression of 52 genes related to cell wall metabolism, thus impairing cell wall metabolism and lowering leaf growth. Cu-toxicity downregulated the expression of photosynthetic electron transport-related genes, thus reducing CO2 assimilation. Some genes involved in thermal energy dissipation, photorespiration, reactive oxygen species scavenging and cell redox homeostasis and some antioxidants (reduced glutathione, phytochelatins, metallothioneins, l-tryptophan and total phenolics) were upregulated in LCGSEC, but they could not protect LCGSEC from oxidative damage. Several adaptive responses might occur in LCGSEC. LCGSEC displayed both enhanced capacities to maintain homeostasis of Cu via reducing Cu uptake by leaves and preventing release of vacuolar Cu into the cytoplasm, and to improve internal detoxification of Cu by accumulating Cu chelators (lignin, reduced glutathione, phytochelatins, metallothioneins, l-tryptophan and total phenolics). The capacities to maintain both energy homeostasis and Ca homeostasis might be upregulated in LCGSEC. Cu-toxicity increased abscisates (auxins) level, thus stimulating stomatal closure and lowering water loss (enhancing water use efficiency and photosynthesis).

Overview of Fibre Optic Sensing Technology in the Field of Physical Ocean Observation

Fiber optic sensors are expected to be an auxiliary measurement tool in the field of ocean observation due to their small size, easy networking, intrinsic immunity to electromagnetic interference, and many other advantages. In recent years, the research around fiber optic sensing technology in the field of physical ocean observation has received increasing attention from researchers. According to the different measurement objects and measurement principles, the focus is on the seawater temperature sensor based on fiber grating, seawater salinity sensor, seawater pressure sensor, seawater salinity sensor based on multi-core optical fiber, seawater salinity sensor based on Michelson and Mach-Zehnder interferometry, seawater pressure sensor based on Fabry-Perot cavity, fiber optic temperature salinity and depth sensors based on resonant and coupling technology, flow velocity sensor based on multi-core optical fiber and fiber optic turbulence sensors based on thermal dissipation and turbulent kinetic energy dissipation. The test methods and test results of various sensors are analyzed, and the advantages and disadvantages of the technologies are pointed out. Prospects for the application of fiber optic sensors in physical ocean observation are presented.

Protein-Protein Interactions Induce pH-Dependent and Zeaxanthin-Independent Photoprotection in the Plant Light-Harvesting Complex, LHCII.

Plants use energy from the sun yet also require protection against the generation of deleterious photoproducts from excess energy. Photoprotection in green plants, known as nonphotochemical quenching (NPQ), involves thermal dissipation of energy and is activated by a series of interrelated factors: a pH drop in the lumen, accumulation of the carotenoid zeaxanthin (Zea), and formation of arrays of pigment-containing antenna complexes. However, understanding their individual contributions and their interactions has been challenging, particularly for the antenna arrays, which are difficult to manipulate in vitro. Here, we achieved systematic and discrete control over the array size for the principal antenna complex, light-harvesting complex II, using near-native in vitro membranes called nanodiscs. Each of the factors had a distinct influence on the level of dissipation, which was characterized by measurements of fluorescence quenching and ultrafast chlorophyll-to-carotenoid energy transfer. First, an increase in array size led to a corresponding increase in dissipation; the dramatic changes in the chlorophyll dynamics suggested that this is due to an allosteric conformational change of the protein. Second, a pH drop increased dissipation but exclusively in the presence of protein-protein interactions. Third, no Zea dependence was identified which suggested that Zea regulates a distinct aspect of NPQ. Collectively, these results indicate that each factor provides a separate type of control knob for photoprotection, which likely enables a flexible and tunable response to solar fluctuations.

Effect of Oxygen Impurity on Thermal Conduction Rate of Polycrystalline Si3N4

Heat transfer with homogeneous structures of Si3N4 system and the effects of oxygen defects in the Si3N4 grains are reported by Jung Woo Lee and co-workers in article number 2100566. The oxygen defects in the grains are moving to the surface of the grains and effectively captured by oxygen getter. The inhibition of the Si3N4 grain oxidization improves a spontaneous dissipation of thermal energy.

Wide variation of winter-induced sustained thermal energy dissipation in conifers: a common-garden study.

Low temperature in winter depresses rates of photosynthesis, which, in evergreen plants, can exacerbate imbalances between light absorption and photochemical light use. Damage that could result from increased excess light absorption is minimized by the conversion of excitation energy to heat in a process known as energy dissipation, which involves the de-epoxidized carotenoids of the xanthophyll cycle. Overwintering evergreens employ sustained forms of energy dissipation observable even after lengthy periods of dark acclimation. Whereas most studies of photoprotective energy dissipation examine one or a small number of species; here, we measured the levels of sustained thermal energy dissipation of seventy conifer taxa growing outdoors under common-garden conditions at the Red Butte Garden in Salt Lake City, Utah, U.S.A. (forty nine taxa were also sampled for needle pigment content). We observed an extremely wide range of wintertime engagement of sustained energy dissipation; the percentage decrease in dark-acclimated photosystem II quantum efficiency from summer to winter ranged from 6 to 95%. Of the many pigment-based parameters measured, the magnitude of the seasonal decrease in quantum efficiency was most closely associated with the seasonal increase in zeaxanthin content expressed on a total chlorophyll basis, which explained only slightly more than one-third of the variation. We did not find evidence for a consistent wintertime decrease in needle chlorophyll content. Thus, the prevailing mechanism for winter decreases in solar-induced fluorescence emitted by evergreen forests may be decreases in fluorescence quantum yield, and wintertime deployment of sustained energy dissipation likely underlies this effect.

Nanoengineered Graphene-Reinforced Coating for Leading Edge Protection of Wind Turbine Blades

Possibilities of the development of new anti-erosion coatings for wind turbine blade surface protection on the basis of nanoengineered polymers are explored. Coatings with graphene and hybrid nanoreinforcements are tested for their anti-erosion performance, using the single point impact fatigue testing (SPIFT) methodology. It is demonstrated that graphene and hybrid (graphene/silica) reinforced polymer coatings can provide better erosion protection with lifetimes up to 13 times longer than non-reinforced polyurethanes. Thermal effects and energy dissipation during the repeated soft impacts on the blade surface are discussed.

The effect of nickel phytotoxicity on photosystem II activity and antioxidant enzymes in barley

In this study, the effect of mild (100 µM), moderate (300 µM) and severe (500 µM) nickel (NiSO4.7H2O) toxicity on the photosynthetic activity, photosynthetic pigment content and some antioxidant enzymes in the leaves of a barley cultivars (Hordeum vulgare L. cv. Tarm-92) was investigated. Moderate and severe nickel toxicity decreased root length while shoot length was not affected by nickel stress, probably due to over accumulation of nickel in roots. Similarly, biomass accumulation was declined by moderate and severe nickel toxicity as reflected by the lowered fresh and dry weight. Chlorophyll a, chlorophyll b and consequently total chlorophyll content decreased by all nickel applications, presumably because the reduced level of carotenoids. Chlorophyll a fluorescence measurements showed that nickel toxicity blocked electron movement in some specific points of the photosynthetic electron transport system. The constant Fo value indicated that PSII reaction centers was not damaged in the leaves of barley under nickel toxicity while the reduced Fm value showed that acceptor side of PSII was more sensitive to nickel toxicity as compared to donor side. Changes in JIP test parameters in the leaves of barley showed that primary photochemical reactions are reduced, and thermal dissipation of excess energy is increased. SOD and CAT activity is elevated in the leaves of barley under moderate and severe nickel toxicity which demonstrate an efficient superoxide dismutation. Severe nickel toxicity, however, did not affect SOD and CAT activity. The ascorbate-glutathione cycle was activated in the leaves of barley plants under nickel toxicity, probably indicating an efficient H2O2 detoxification. However, considerable H2O2 and MDA accumulation was observed in the leaves of barley under nickel stress. As a result, it may be concluded that the barley genotype Tarm-92 is moderately tolerant to nickel toxicity.

Deuterated Covalent Organic Frameworks with Significantly Enhanced Luminescence.

Luminescent covalent organic frameworks (COFs) find promising applications in chemical sensing, photocatalysis, and optoelectronic devices, however, the majority of COFs are non or weakly emissive owing to the aggregation-caused quenching (ACQ) or the molecular thermal motion-based energy dissipation. Here, we report a previously unperceived approach to improve luminescence performance of COFs by introducing isotope effect, which is achieved through substitution of hydrogen from high-frequency oscillators X-H (X=O, N, C) by heavier isotope deuterium. Combining the "bottom-up" and in situ deuteration methods generates the first deuterated COF, which exhibits an impressively 19-fold enhancement in quantum yield over that of the non-deuterated counterpart. These results are interpreted by theoretical calculations as the consequence of slower C/N-D and OD⋅⋅⋅O vibrations that impede the nonradiative deactivation process. The proposed strategy is proved applicable to many other types of emissive COFs.

Cooperation of chloroplast ascorbate peroxidases and proton gradient regulation 5 is critical for protecting Arabidopsis plants from photo-oxidative stress.

High-light (HL) stress enhances the production of H2 O2 from the photosynthetic electron transport chain in chloroplasts, potentially causing photo-oxidative damage. Although stromal and thylakoid membrane-bound ascorbate peroxidases (sAPX and tAPX, respectively) are major H2 O2 -scavenging enzymes in chloroplasts, their knockout mutants do not exhibit a visible phenotype under HL stress. Trans-thylakoid proton gradient (∆pH)-dependent mechanisms exist for controlling H2 O2 production from photosynthesis, such as thermal dissipation of light energy and downregulation of electron transfer between photosystems II and I, and these may compensate for the lack of APXs. To test this hypothesis, we focused on a proton gradient regulation 5 (pgr5) mutant, wherein both ∆pH-dependent mechanisms are impaired, and an Arabidopsis sapx tapx double mutant was crossed with the pgr5 single mutant. The sapx tapx pgr5 triple mutant exhibited extreme sensitivity to HL compared with its parental lines. This phenotype was consistent with cellular redox perturbations and enhanced expression of many oxidative stress-responsive genes. These findings demonstrate that the PGR5-dependent mechanisms compensate for chloroplast APXs, and vice versa. An intriguing finding was that the failure of induction of non-photochemical quenching in pgr5 (because of the limitation in ∆pH formation) was partially recovered in sapx tapx pgr5. Further genetic studies suggested that this recovery was dependent on the NADH dehydrogenase-like complex-dependent pathway for cyclic electron flow around photosystem I. Together with data from the sapx tapx npq4 mutant, we discuss the interrelationship between APXs and ∆pH-dependent mechanisms under HL stress.

Corrected photochemical reflectance index (PRI) is an effective tool for detecting environmental stresses in agricultural crops under light conditions.

High-throughput detection of plant environmental stresses is required for minimizing the reduction in crop yield. Environmental stresses in plants have primarily been validated by the measurements of photosynthesis with gas exchange and chlorophyll fluorescence, which involve complicated procedures. Remote sensing technologies that monitor leaf reflectance in intact plants enable real-time visualization of plant responses to environmental fluctuations. The photochemical reflectance index (PRI), one of the vegetation indices of spectral leaf reflectance, is related to changes in xanthophyll pigment composition. Xanthophyll dynamics are strongly correlated with plant stress because they contribute to the thermal dissipation of excess energy. However, an accurate assessment of plant stress based on PRI requires correction by baseline PRI (PRIo) in the dark, which is difficult to obtain in the field. In this study, we propose a method to correct the PRI using NPQT, which can be measured under light. By this method, we evaluated responses of excess light energy stress under drought in wild watermelon (Citrullus lanatus L.), a xerophyte. Demonstration on the farm, the stress behaviors were observed in maize (Zea mays L.). Furthermore, the stress status of plants and their recovery following re-watering were captured as visual information. These results suggest that the PRI is an excellent indicator of environmental stress and recovery in plants and could be used as a high-throughput stress detection tool in agriculture.

Key photoprotective pathways of a shade-tolerant plant (Alpinia oxyphylla) for precipitation patterns change during the dry season: thermal energy dissipation and water-water cycle

Alpinia oxyphylla Miq is a shade-tolerant plant that grows under rubber trees. The decreased precipitation often leads to limitation of photosynthesis and productivity of A. oxyphylla during the dry season. However, the effects of the precipitation patterns on the photosynthesis and the photoprotective strategies of A. oxyphylla remains unclear. Herein, we examined how CO2 assimilation, light energy partitioning and reactive oxygen species (ROS) metabolism are affected by simulated precipitation patterns change. The change of precipitation patterns induced water deficits of different intensities and durations. With the decreased precipitation, stomatal conductance (Gs) and net CO2 assimilation rate (Pn) significantly decreased, resulting in excess excitation energy and over-accumulation of ROS, and further caused lipid peroxidation of photosynthetic apparatus. The phenomenon was exacerbated by extending the interval between precipitation. In addition, the decreased precipitation induced the xanthophyll cycle effectively dissipating excess excitation energy. Through the water-water cycle, a greater proportion of electron flux was shuffled to molecular oxygen (O2) to produce superoxide anion (O2•−), especially in plants under natural precipitation (W; 25 mm/month). This may be because the energy partitioning mechanism of A. oxyphylla can efficiently dissipate excessive excitation energy and reduce PSⅡ photoinhibition, thus rapidly adapting to precipitation patterns change. On the other hand, the decreased precipitation improved the capacity of ROS detoxification in the water-water cycle and reduced lipid peroxidation in W plants, which were reflected by the increase of SOD and CAT activities, and a partial enhancement of antioxidant enzymes and antioxidant metabolism in the water-water cycle. However, the down-regulation of antioxidant systems in W- plants (decreased precipitation; 10 mm/month) further accelerated ROS accumulation and the ability of ROS-scavenging might be partially compensated by ROS accumulation, which may had been a primary cause for limited the antioxidant protection. Overall, when CO2 assimilation reduced with the decreased precipitation, A. oxyphylla can form a photoprotective mechanism, both thermal energy dissipation and water-water cycle are crucial photoprotective pathways against photodamage in photosynthetic apparatus.

Connecting boundary layer dynamics with extreme bulk dissipation events in Rayleigh-Bénard flow (a) (a)Contribution to the Focus Issue Turbulent Thermal Convection edited by Mahendra Verma and Jörg Schumacher.

We study the connection between extreme events of thermal and kinetic energy dissipation rates in the bulk of three-dimensional Rayleigh-Bénard convection and the wall shear stress patterns at the top and the bottom plates that enclose the layer. Zero points of this two-dimensional vector field stand for detachments of strong thermal plumes. If their position at the opposite plates and a given time is close then they can be considered as precursors for high-amplitude bulk dissipation events triggered by plume collisions or close passings. This scenario requires a breaking of the synchronicity of the boundary layer dynamics at both plates which is found to be in line with a transition of the bulk derivative statistics from Gaussian to intermittent. Our studies are based on three-dimensional high-resolution direct numerical simulations for moderate Rayleigh numbers between and .

LIGHT ENERGY UTILIZATION AND CHLOROPHYLL FLUORESCENCE IN TWO CROSSBREED POPLARS

Aims Our objective was to study two widely planted hybrid poplars,Populus deltaids 'cv-64' (P64) and P. simonii canaden × P. russkii-9 (Jia),to explore their growth mechanisms and the solar energy utilization by photosystem II (PSII) antennae to thermal energy dissipation and photosyn-thetic electron transport characteristics during long-term adaptation to the ambient environment. Methods We studied energy utilization by computing chlorophyll fluorescence parameters and photo-synthesis. Plants were grown at the Plain Forest Farm Nursery of the State Forestry Bureau of Ili Autonomous Prefecture in China's Xinjiang region. Important findings The diurnal changes of net photosynthesis (Pn) were bimodal and had a 20.1% gap under high photon flux density (PFD). The actual efficiency of open PSII centers (ΦPSII) were all of the "U" type,and their average values were equal. The ΦPSII of P64 and Jia reached the minimum value at 16:30 and 14:30,respectively. The closure value had one wave hollow at 14:30,and there was no significant difference (p0.05) in whole-day average values. The non-photochemical quenching co-efficients (NPQ) all achieved the maximum value at 16:30. Jia's NPQ maximum was less than that of P64,and the whole-day NPQ difference reached 31.7%. The estimated rates of photochemistry (E.P) and non-photochemistry (E.D) showed that under the lower PFD the poplars used more than 50% of theabsorbed solar energy for the photochemical quenching,and under high PFD the absorbed solar energy for P64 for the photochemical quenching is greater than the proportion for Jia,while the absorbed solar energy for P64 for heat dissipation is less than the proportion for Jia. The E.P had no difference and reached the maximum estimated value when its E.D reached the maximum. P64 tended to use more ab-sorbed solar energy for photochemical quenching,but Jia tended to use more solar energy for non-photochemical quenching. The cumulative values and average values of the Pn for Jia were much larger than values for P64,but the absorbed solar energy of P64 is greater than the proportion of Jia for the photochemical quenching. These results prove that it is inadequate to calculate the absorbed energy only by the chloroplast fluorescent characteristics of light received.

Use of Cuckoo Search Algorithm for Performance Evaluation of Split Elliptic Shaped Fins for Enhanced Rate of Heat Transfer

Abstract Proper dissipation of thermal energy has always been a need for desirable efficiency of a system. Extended surface aids in releasing the heat to the immediate surrounding by inducing an extra area. This particular work assesses thermal and fluid flow behavior of extended surfaces with circular and elliptic shaped cross section. Extended surfaces of unvaried cross section are mounted over a square plate arrayed in a staggered manner. With the aid of different thermofluidic parameters, the elliptic shaped pin fin is established to provide a higher thermal performance enhancement of nearly 15% over cylindrical pin fin at inlet flow velocity of 2.35 m/s. Further, for elevating the interaction between the surface of the fin and the fluid, elliptic fins are reoriented to form a split. In contrast to cylindrical shaped fin, modification using split shows better result with the highest heat transfer increment of nearly 25%. Further, in order to maximize Nusselt number (Nu), a single objective cuckoo search optimization analysis is done by adopting the response surface method. After analyzing the optimization, it is found that the maximum value of Nu is obtained at dimensionless transverse offset (TO*) = 0.125 and dimensionless longitudinal offset (LO*) = 0, which has been further validated with the numerical result within 0.97% accuracy. Further, for the cylindrical fin, the present simulations agree with the available empirical correlation within 6.22% accuracy.

Particle film technology modulates xanthophyll cycle and photochemical dynamics of grapevines grown in the Douro Valley

Field-grown grapevines are often exposed to multiple environmental stresses, which challenges wine-growers to develop sustainable measures to sustain vine growth, yield, and quality. Under field conditions this task is demanding, due to differences in the magnitudes of stresses and associated plant responses. In this study we explored the hypothesis that kaolin-particle film application improves grapevine photoprotection through the regulation of xanthophyll cycle genes, limiting the thermal dissipation of excess energy under harsh environmental conditions. Hence, we selected two grapevine varieties, Touriga-Nacional (TN) and Touriga-Franca (TF), grown in the Douro Demarcated Region, and evaluated changes in light dissipation mechanisms, xanthophyll cycle components, and the expression of xanthophyll cycle genes during the 2017 summer season. The results showed that, from veraison to ripening, kaolin triggered the up-regulation of violaxanthin de-epoxidase (VvVDE1) and zeaxanthin epoxidase (VvZEP1) genes, indicating optimised regulation of the xanthophyll cycle. Kaolin treatment also decreased chlorophyll (Chla, Chlb, Chl(a+b)) and carotenoid (Car) accumulation under increasing summer stress conditions in both varieties and lowered the non-photochemical quenching (NPQ) of grapevines on ripening, suggesting a long-term response to summer stress. In addition, kaolin-treated grapevines showed increased Chla/Chlb and lower Chl(a+b)/Car ratios, displaying some features of high light adapted leaves. Overall, this study suggests that kaolin application enabled grapevines to benefit from fluctuating periods of summer stress by managing chlorophyll and carotenoid content and limiting down-regulation of both photochemistry and photoinhibition processes. Under Mediterranean field conditions, kaolin application can be considered an efficient method of minimising summer stress impact on grapevines.

Modular, Flexible, Low-Cost Microstructure Measurements: The Epsilometer

AbstractThe Epsilometer (“epsi”) is a small (7 cm diameter × 30 cm long), low-power (0.15 W), and extremely modular microstructure package measuring thermal and kinetic energy dissipation rates, χ and ε. Both the shear probes and FP07 temperature sensors are fabricated in house following techniques developed by Michael Gregg at the Applied Physics Laboratory/University of Washington (APL/UW). Sampling eight channels (two shear, two temperature, three-axis accelerometer, and a spare for future sensors) at 24 bit precision and 325 Hz, the system can be deployed in standalone mode (battery power and recording to microSD cards) for deployment on autonomous vehicles, wave powered profilers, or it can be used with dropping body termed the “epsi-fish” for profiling from boats, autonomous surface craft or ships with electric fishing reels or other simple winches. The epsi-fish can also be used in real-time mode with the Scripps “fast CTD” winch for fully streaming, altimeter-equipped, line-powered, rapid-repeating, near-bottom shipboard profiles to 2200 m. Because this winch has a 25 ft (~7.6 m) boom deployable outboard from the ship, contamination by ship wake is reduced one to two orders of magnitude in the upper 10–15 m. The noise floor of ε profiles from the epsi-fish is ~10−10 W kg−1. This paper describes the fabrication, electronics, and characteristics of the system, and documents its performance compared to its predecessor, the APL/UW Modular Microstructure Profiler (MMP).

Triploidy in Citrus Genotypes Improves Leaf Gas Exchange and Antioxidant Recovery From Water Deficit.

The triploidy has proved to be a powerful approach breeding programs, especially in Citrus since seedlessness is one of the main consumer expectations. Citrus plants face numerous abiotic stresses including water deficit, which negatively impact growth and crop yield. In this study, we evaluated the physiological and biochemical responses to water deficit and recovery capacity of new triploid hybrids, in comparison with diploid hybrids, their parents (“Fortune” mandarin and “Ellendale” tangor) and one clementine tree used as reference. The water deficit significantly decreased the relative water content (RWC) and leaf gas exchange (Pnet and gs) and it increased the levels of oxidative markers (H2O2 and MDA) and antioxidants. Compared to diploid varieties, triploid hybrids limited water loss by osmotic adjustment as reflected by higher RWC, intrinsic water use efficiency (iWUE Pnet/gs) iWUE and leaf proline levels. These had been associated with an effective thermal dissipation of excess energy (NPQ) and lower oxidative damage. Our results showed that triploidy in citrus enhances the recovery capacity after a water deficit in comparison with diploids due to better carboxylation efficiency, restored water-related parameters and efficient antioxidant system.