Linking thermal imaging to physiological indicators in Carica papaya L. under different watering regimes

Water deficit is the most limiting factor for yield and fruit-quality parameters in papaya crop (Carica papaya L.), deficit-irrigation (DI) strategies offering a feasible alternative to manage limiting water resources. When DI is applied, it is crucial to assess the physiological status of the crop in order to maintain the plant within a threshold value of water stress so as no to affect yield or fruit-quality parameters. The aim of this work was to evaluate the feasibility of thermal imaging in young papaya plants to assess the physiological status of this crop when it is subjected to different DI regimes, studying the relationships between the changes in leaf temperature (Tleaf) and in the major physiological parameters (i.e., stomatal conductance to water vapor, gs; transpiration, E; and net photosynthesis, An). The trial was conducted in a greenhouse from March to April of 2012. Plants were grown in pots and subjected to four irrigation treatments: (1) a full irrigation treatment (control), maintained at field capacity; (2) a partial root-zone drying treatment, irrigated with 50% of the total water applied to control to only one side of roots, alternating the sides every 7 days; (3) a regulated deficit irrigation (50% of the control, applied to both sides of plant); (4) and a non-irrigated treatment, in which irrigation was withheld from both sides of the split root for 14 days, followed by full irrigation until the end of the study. Significant relationships were found between Tleaf and major physiological variables such as gs, E and An. Additionally, significant relationships were found between the difference of leaf-to-air temperature (ΔTleaf–air) and gas-exchange measurements, which were used to establish the optimum range of ΔTleaf–air as a preliminary step to the crop-water monitoring and irrigation scheduling in papaya, using thermal imaging as the main source of information. According to the results, we conclude that thermal imaging is a promising technique to monitor the physiological status of papaya during drought conditions.

Thermal tweezers for manipulation of adatoms and nanoparticles on surfaces heated by interfering laser pulses

We conduct the detailed numerical investigation of a nanomanipulation and nanofabrication technique—thermal tweezers with dynamic evolution of surface temperature, caused by absorption of interfering laser pulses in a thin metalfilm or any other absorbing surface. This technique uses random Brownian forces in the presence of strong temperature modulation (surfacethermophoresis) for effective manipulation of particles/adatoms with nanoscale resolution. Substantial redistribution of particles on the surface is shown to occur with the typical size of the obtained pattern elements of ∼100 nm, which is significantly smaller than the wavelength of the incident pulses used (532 nm). It is also demonstrated that thermal tweezers based on surfacethermophoresis of particles/adatoms are much more effective in achieving permanent high maximum-to-minimum concentration ratios than bulk thermophoresis, which is explained by the interaction of diffusing particles with the periodic lattice potential on the surface. Typically required pulse regimes including pulse lengths and energies are also determined. The approach is applicable for reproducing any holographically achievable surfacepatterns, and can thus be used for engineering properties of surfaces including nanopatterning and design of surface metamaterials.

Physics-Based Thermal Conductivity Model for Metallic Single-Walled Carbon Nanotube Interconnects

In this letter, a closed-form analytical model for temperature-dependent longitudinal diffusive lattice thermal conductivity (kappa) of a metallic single-walled carbon nanotube (SWCNT) has been addressed. Based on the Debye theory, the second-order three-phonon Umklapp, mass difference (MD), and boundary scatterings have been incorporated to formulate. in both low-and high-temperature regimes. It is proposed that. at low temperature (T) follows the T-3 law and is independent of the second-order three-phonon Umklapp and MD scatterings. The form factor due to MD scattering also plays a key role in the significant variation of. in addition to the SWCNT length. The present diameter-independent model of. agrees well with the available experimental data on suspended intrinsic metallic SWCNTs over a wide range of temperature and can be carried forward for electrothermal analyses of CNT-based interconnects.

Rapid thermal processed thin films of niobium pentoxide (Nb2 O5) deposited by reactive magnetron sputtering

Niobium pentoxide thin films have been deposited on silicon and platinum-coated silicon substrates by reactive magnetron sputtering. The as-deposited films were amorphous and showed good electrical properties in terms of a dielectric permittivity of about 30, and leakage current density of 10(-6) A cm(-2) al a field of 120 kV cm(-1). A rapid thermal annealing process at 800 degrees C further increased the dielectric constant to 90 and increased the leakage current density to 5 x 10(-6) A cm(-2). The current-voltage characteristics observed at low and high fields suggested a combination of phenomena at different regimes of applied electric field. The capacitance-voltage characteristics performed in the metal-insulator-semiconductor configuration indicated good electronic interfaces with a nominal trap density of 4.5 x 10(12) cm(-2) eV(-1), which is consistent with the behavior observed with conventional dielectrics such as SiO2 on silicon surfaces.

Experimental Study on the Thermal Argon Plasma Generation and Jet Length Change Characteristics at Atmospheric Pressure

The generation, jet length and flow-regime change characteristics of argon plasma issuing into ambient air have been experimentally examined. Different torch structures have been used in the tests. Laminar plasma jets can be generated within a rather wide range of working-gas flow rates, and an unsteady transitional flow state exists between the laminar and turbulent flow regimes. The high-temperature region length of the laminar plasma jet can be over an order longer than that of the turbulent plasma jet and increases with increasing argon flow rate or arc current, while the jet length of the turbulent plasma is less influenced by the generating parameters. The flow field of the plasma jet has very high radial gradients of plasma parameters, and a Reynolds number alone calculated in the ordinary manner may not adequately serve as a criterion for transition. The laminar plasma jet can have a higher velocity than that of an unsteady or turbulent jet. The long laminar plasma jet has good stiffness to withstand the impact of laterally injected cold gas and particulate matter. It could be used as a rather ideal object for fundamental studies and be applied to novel materials processing due to its attractive stable and adjustable properties.

Photo thermal induced effects on testes and pituitary gonadotropic cells during resting phase of reproductive cycle in a murrel, Channa punctatus (Bloch)

Effects of various combinations of photoperiod and temperature (NL-NT, LD 15:9-28°C, NL-28°C and LD 15:9 NT) were studied on testicular activity and pituitary gonadotropic cells in Channa punctatus during resting phase of reproductive cycle. Long photoperiod (LD 15:9-28°C) and warm temperature (NL-28°C) regimes were found to be more effective for testicular maturation and secretory activity of gonadotropic cells suggesting testicular maturation via brain-pituitary-testicular axis.

Product scheduling for thermal energy reduction in papermaking industries

Papermaking is considered as an energy-intensive industry partly due to the fact that the machinery and procedures have been designed at the time when energy was both cheap and plentiful. A typical paper machine manufactures a variety of different products (grades) which impose variable per-unit raw material and energy costs to the mill. It is known that during a grade change operation the products are not market-worthy. Therefore, two different production regimes, i.e. steady state and grade transition can be recognised in papermaking practice. Among the costs associated with paper manufacture, the energy cost is 'more variable' due to (usually) day-to-day variations of the energy prices. Moreover, the production of a grade is often constrained by customer delivery time requirements. Given the above constraints and production modes, the product scheduling technique proposed in this paper aims at optimising the sequence of orders in a single machine so that the cost of production (mainly determined by the energy) is minimised. Simulation results obtained from a commercial board machine in the UK confirm the effectiveness of the proposed method. © 2011 IFAC.

Thermal and quantum fluctuations in chains of ultracold polar molecules

Ultracold polar molecules, in highly anisotropic traps and interacting via a repulsive dipolar potential, may form one-dimensional chains at high densities. According to classical theory, at low temperatures there exists a critical value of the density at which a second-order phase transition from a linear to a zigzag chain occurs. We study the effect of thermal and quantum fluctuations on these self-organized structures using classical and quantum Monte Carlo methods, by means of which we evaluate the pair correlation function and the static structure factor. Depending on the parameters, these functions exhibit properties typical of a crystalline or of a liquid system. We compare the thermal and the quantum results, identifying analogies and differences. Finally, we discuss experimental parameter regimes where the effects of quantum fluctuations on the linear-zigzag transition can be observed.

Development and Validation of a Compact Thermal Model for an Aircraft Compartment

The development of accurate structural/thermal numerical models of complex systems, such as aircraft fuselage barrels, is often limited and determined by the smallest scales that need to be modelled. The development of reduced order models of the smallest scales and consequently their integration with higher level models can be a way to minimise the bottle neck present, while still having efficient, robust and accurate numerical models. In this paper a methodology on how to develop compact thermal fluid models (CTFMs) for compartments where mixed convection regimes are present is demonstrated. Detailed numerical simulations (CFD) have been developed for an aircraft crown compartment and validated against experimental data obtained from a 1:1 scale compartment rig. The crown compartment is defined as the confined area between the upper fuselage and the passenger cabin in a single aisle commercial aircraft. CFD results were utilised to extract average quantities (temperature and heat fluxes) and characteristic parameters (heat transfer coefficients) to generate CTFMs. The CTFMs have then been compared with the results obtained from the detailed models showing average errors for temperature predictions lower than 5%. This error can be deemed acceptable when compared to the nominal experimental error associated with the thermocouple measurements.

The CTFMs methodology developed allows to generate accurate reduced order models where accuracy is restricted to the region of Boundary Conditions applied. This limitation arises from the sensitivity of the internal flow structures to the applied boundary condition set. CTFMs thus generated can be then integrated in complex numerical modelling of whole fuselage sections.

Further steps in the development of an exhaustive methodology would be the implementation of a logic ruled based approach to extract directly from the CFD simulations numbers and positions of the nodes for the CTFM.

Heat transport in harmonic oscillator systems with thermal baths: application to optomechanical arrays

We investigate the transport of phonons between N harmonic oscillators in contact with independent thermal baths and coupled to a common oscillator, and derive an expression for the steady state heat flow between the oscillators in the weak coupling limit. We apply these results to an optomechanical array consisting of a pair of mechanical resonators coupled to a single quantized electromagnetic field mode by radiation pressure as well as to thermal baths with different temperatures. In the weak coupling limit this system is shown to be equivalent to two mutually-coupled harmonic oscillators in contact with an effective common thermal bath in addition to their independent baths. The steady state occupation numbers and heat flows are derived and discussed in various regimes of interest.

Nonequilibrium processes from generalized Langevin equations: Realistic nanoscale systems connected to two thermal baths

We extend the generalized Langevin equation (GLE) method [L. Stella, C. D. Lorenz, and L. Kantorovich, Phys. Rev. B 89, 134303 (2014)] to model a central classical region connected to two realistic thermal baths at two different temperatures. In such nonequilibrium conditions a heat flow is established, via the central system, in between the two baths. The GLE-2B (GLE two baths) scheme permits us to have a realistic description of both the dissipative central system and its surrounding baths. Following the original GLE approach, the extended Langevin dynamics scheme is modified to take into account two sets of auxiliary degrees of freedom corresponding to the mapping of the vibrational properties of each bath. These auxiliary variables are then used to solve the non-Markovian dissipative dynamics of the central region. The resulting algorithm is used to study a model of a short Al nanowire connected to two baths. The results of the simulations using the GLE-2B approach are compared to the results of other simulations that were carried out using standard thermostatting approaches (based on Markovian Langevin and Nosé-Hoover thermostats). We concentrate on the steady-state regime and study the establishment of a local temperature profile within the system. The conditions for obtaining a flat profile or a temperature gradient are examined in detail, in agreement with earlier studies. The results show that the GLE-2B approach is able to treat, within a single scheme, two widely different thermal transport regimes, i.e., ballistic systems, with no temperature gradient, and diffusive systems with a temperature gradient.

The effects of static and diurnally-cycling temperature acclimations on thermal tolerances of rainbow trout, Salmo gairdneri

:ofiedian lethal temperatures ( LT50' s ) were determined for rainbow trout, Salmo gairdnerii, acclimated for a minimum of 21 days at 5 c onstant temperatures between 4 and 20 0 C. and 2 diel temperature fluctuations ( sinewave curves of amplitudes ± 4 and ± 7 0 C. about a mean temperature of 12 0 C. ) . Twenty-four-, 48-, and 96-hour LT50 estimates were c alculated f ollowing standard flow-through aquatic bioassay techniques and probi t transformation of mortality data. The phenomenon of delayed thermal mortality was also investigated. Shifts in upper incipient lethal temperature occurred as a result of previous thermal conditioning. It was shown that increases in constant acclimation temperature result in proportional l inear increases in thermal tolerances. The increase i n estimated 96-hour LT50's was approximately 0.13 0 c. X 1 0 C:1 between 8 and 20 0 C. The effect of acclimation to both cyclic temperature regimes was an increase in LT50 to values between the mean and maximum constant equivalent daily temperatures of the cycles. Twenty-four-, 48-, and 96-hour LT50 estimates of both cycles corresponded approximately to the LT50 values of the 16 0 C. c onstant temperature equivalent . This increase i n thermal tolerance was further demonstrated by the delayed thermal mortality experiments . Cycle amplitudes appeared to i nfluence thermal resistance through alterations in initi al mortality since mortality patterns characteristic of base temperature acclimations re-appeared after approximately 68 hours exposure to test temperatures for the 12 + 4 0 C. group, whereas mortality patterns stabilized and remained constant for a period greater than 192 hours with the larger therma l cycle ( 12 + 7 0 C. ). NO s ignificant corre lations between s pecimen weight and time-to-death was apparent. Data are discussed in relation to the establishment of thermal criteria for important commercial and sport fishes , such as the salmonids , as is the question whether previously reported values on lethal temperature s may have been under estimated.

Composition and stability of organic matter fractions in soils under different land use regimes

Soil organic matter (SOM) vitally impacts all soil functions and plays a key role in the global carbon (C) cycle. More than 70% of the terrestric C stocks that participate in the active C cycle are stored in the soil. Therefore, quantitative knowledge of the rates of C incorporation into SOM fractions of different residence time is crucial to understand and predict the sequestration and stabilization of soil organic carbon (SOC). Consequently, there is a need of fractionation procedures that are capable of isolating functionally SOM fractions, i.e. fractions that are defined by their stability. The literature generally refers to three main mechanisms of SOM stabilization: protection of SOM from decomposition by (i) its structural composition, i.e. recalcitrance, (ii) spatial inaccessibility and/or (iii) interaction with soil minerals and metal ions. One of the difficulties in developing fractionation procedures for the isolation of functional SOM fractions is the marked heterogeneity of the soil environment with its various stabilization mechanisms – often several mechanisms operating simultaneously – in soils and soil horizons of different texture and mineralogy. The overall objective of the present thesis was to evaluate present fractionation techniques and to get a better understanding of the factors of SOM sequestration and stabilization. The first part of this study is attended to the structural composition of SOM. Using 13C cross-polarization magic-angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, (i) the effect of land use on SOM composition was investigated and (ii) examined whether SOM composition contributes to the different stability of SOM in density and aggregate fractions. The second part of the present work deals with the mineral-associated SOM fraction. The aim was (iii) to evaluate the suitability of chemical fractionation procedures used in the literature for the isolation of stable SOM pools (stepwise hydrolysis, treatments using oxidizing agents like Na2S2O8, H2O2, and NaOCl as well as demineralization of the residue obtained by the NaOCl treatment using HF (NaOCl+HF)) by pool sizes, 13C and 14C data. Further, (iv) the isolated SOM fractions were compared to the inert organic matter (IOM) pool obtained for the investigated soils using the Rothamsted Carbon Model and isotope data in order to see whether the tested chemical fractionation methods produce SOM fractions capable to represent this pool. Besides chemical fractionation, (v) the suitability of thermal oxidation at different temperatures for obtaining stable SOC pools was evaluated. Finally, (vi) the short-term aggregate dynamics and the factors that impact macroaggregate formation and C stabilization were investigated by means of an incubation study using treatments with and without application of 15N labeled maize straw of different degradability (leaves and coarse roots). All treatments were conducted with and without the addition of fungicide. Two study sites with different soil properties and land managements were chosen for these investigations. The first one, located at Rotthalmünster, is a Stagnic Luvisol (silty loam) under different land use regimes. The Ah horizons of a spruce forest and continuous grassland and the Ap and E horizons of two plots with arable crops (continuous maize and wheat cropping) were examined. The soil of the second study site, located at Halle, is a Haplic Phaeozem (loamy sand) where the Ap horizons of two plots with arable crops (continuous maize and rye cropping) were investigated. Both study sites had a C3-/C4-vegetational change on the maize plot for the purpose of tracing the incorporation of the younger, maize-derived C into different SOM fractions and the calculation of apparent C turnover times of these. The Halle site is located near a train station and industrial areas, which caused a contamination with high amounts of fossil C. The investigation of aggregate and density fractions by 13C CPMAS NMR spectroscopy revealed that density fractionation isolated SOM fractions of different composition. The consumption of a considerable part (10–20%) of the easily available O-alkyl-C and the selective preservation of the more recalcitrant alkyl-C when passing from litter to the different particulate organic matter (POM) fractions suggest that density fractionation was able to isolate SOM fractions with different degrees of decomposition. The spectra of the aggregate fractions resembled those of the mineral-associated SOM fraction obtained by density fractionation and no considerable differences were observed between aggregate size classes. Comparison of plant litter, density and aggregate size fractions from soil under different land use showed that the type of land use markedly influenced the composition of SOM. While SOM of the acid forest soil was characterized by a large content (> 50%) of POM, which contained high amounts of spruce-litter derived alkyl-C, the organic matter in the biologically more active grassland and arable soils was dominated by mineral-associated SOM (> 95%). This SOM fraction comprised greater proportions of aryl- and carbonyl-C and is considered to contain a higher amount of microbially-derived organic substances. Land use can alter both, structure and stability of SOM fractions. All applied chemical treatments induced considerable SOC losses (> 70–95% of mineral-associated SOM) in the investigated soils. The proportion of residual C after chemical fractionation was largest in the arable Ap and E horizons and increased with decreasing C content in the initial SOC after stepwise hydrolysis as well as after the oxidative treatments with H2O2 and Na2S2O8. This can be expected for a functional stable pool of SOM, because it is assumed that the more easily available part of SOC is consumed first if C inputs decrease. All chemical treatments led to a preferential loss of the younger, maize-derived SOC, but this was most pronounced after the treatments with Na2S2O8 and H2O2. After all chemical fractionations, the mean 14C ages of SOC were higher than in the mineral-associated SOM fraction for both study sites and increased in the order: NaOCl < NaOCl+HF ≤ stepwise hydrolysis << H2O2 ≈ Na2S2O8. The results suggest that all treatments were capable of isolating a more stable SOM fraction, but the treatments with H2O2 and Na2S2O8 were the most efficient ones. However, none of the chemical fractionation methods was able to fit the IOM pool calculated using the Rothamsted Carbon Model and isotope data. In the evaluation of thermal oxidation for obtaining stable C fractions, SOC losses increased with temperature from 24–48% (200°C) to 100% (500°C). In the Halle maize Ap horizon, losses of the young, maize-derived C were considerably higher than losses of the older C3-derived C, leading to an increase in the apparent C turnover time from 220 years in mineral-associated SOC to 1158 years after thermal oxidation at 300°C. Most likely, the preferential loss of maize-derived C in the Halle soil was caused by the presence of the high amounts of fossil C mentioned above, which make up a relatively large thermally stable C3-C pool in this soil. This agrees with lower overall SOC losses for the Halle Ap horizon compared to the Rotthalmünster Ap horizon. In the Rotthalmünster soil only slightly more maize-derived than C3-derived SOC was removed by thermal oxidation. Apparent C turnover times increased slightly from 58 years in mineral-associated SOC to 77 years after thermal oxidation at 300°C in the Rotthalmünster Ap and from 151 to 247 years in the Rotthalmünster E horizon. This led to the conclusion that thermal oxidation of SOM was not capable of isolating SOM fractions of considerably higher stability. The incubation experiment showed that macroaggregates develop rapidly after the addition of easily available plant residues. Within the first four weeks of incubation, the maximum aggregation was reached in all treatments without addition of fungicide. The formation of water-stable macroaggregates was related to the size of the microbial biomass pool and its activity. Furthermore, fungi were found to be crucial for the development of soil macroaggregates as the formation of water-stable macroaggregates was significantly delayed in the fungicide treated soils. The C concentration in the obtained aggregate fractions decreased with decreasing aggregate size class, which is in line with the aggregate hierarchy postulated by several authors for soils with SOM as the major binding agent. Macroaggregation involved incorporation of large amounts maize-derived organic matter, but macroaggregates did not play the most important role in the stabilization of maize-derived SOM, because of their relatively low amount (less than 10% of the soil mass). Furthermore, the maize-derived organic matter was quickly incorporated into all aggregate size classes. The microaggregate fraction stored the largest quantities of maize-derived C and N – up to 70% of the residual maize-C and -N were stored in this fraction.

High pressure/thermal treatment effects on the texture of beef muscle

The effects of high pressure (to 800 MPa) applied at different temperatures (20-70 degreesC) for 20 min on beef post-rigor longissimus dorsi texture were studied. Texture profile analysis showed that when heated at ambient pressure there was the expected increase in hardness with increasing temperature and when pressure was applied at room temperature there was again the expected increase in hardness with increasing pressure. Similar results to those found at ambient temperature were found when pressure was applied at 40 degreesC. However, at higher temperatures, 60 and 70 degreesC it was found that pressures of 200 MPa caused large and significant decreases in hardness. The results found for hardness were mirrored by those for gumminess and chewiness. To further understand the changes in texture observed, intact beef longissimus dorsi samples and extracted myofibrils were both subjected to differential scanning calorimetry after being subjected to the same pressure/temperature regimes. As expected collagen was reasonably inert to pressure and only at temperatures of 60-70 degreesC was it denatured/unfolded. However, myosin was relatively easily unfolded by both pressure and temperature and when pressure denatured a new and modified structure was formed of low thermal stability. Although this new structure had low thermal stability at ambient pressure it still formed in both the meat and myofibrils when pressure was applied at 60 degreesC. It seems unlikely that structurally induced changes can be a major cause of the significant loss of hardness observed when beef is treated at high temperature (60-70 degreesC) and 200 MPa and it is suggested that accelerated proteolysis under these conditions is the major cause. (C) 2004 Elsevier Ltd. All rights reserved.

Experimental evolution for generalists and specialists reveals multivariate genetic constraints on thermal reaction norms

Theory predicts the emergence of generalists in variable environments and antagonistic pleiotropy to favour specialists in constant environments, but empirical data seldom support such generalist–specialist trade-offs. We selected for generalists and specialists in the dung fly Sepsis punctum (Diptera: Sepsidae) under conditions that we predicted would reveal antagonistic pleiotropy and multivariate trade-offs underlying thermal reaction norms for juvenile development. We performed replicated laboratory evolution using four treatments: adaptation at a hot (31 °C) or a cold (15 °C) temperature, or under regimes fluctuating between these temperatures, either within or between generations. After 20 generations, we assessed parental effects and genetic responses of thermal reaction norms for three correlated life-history traits: size at maturity, juvenile growth rate and juvenile survival. We find evidence for antagonistic pleiotropy for performance at hot and cold temperatures, and a temperature-mediated trade-off between juvenile survival and size at maturity, suggesting that trade-offs associated with environmental tolerance can arise via intensified evolutionary compromises between genetically correlated traits. However, despite this antagonistic pleiotropy, we found no support for the evolution of increased thermal tolerance breadth at the expense of reduced maximal performance, suggesting low genetic variance in the generalist–specialist dimension.