scholarly journals Induction of 1-FEH in Mature Chicory Roots Appears to be Related to Low Temperatures Rather than to Leaf Damage

2002 ◽  
Vol 2 ◽  
pp. 1750-1761 ◽  
Author(s):  
W. Van den Ende ◽  
A. Van Laere
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Large Scale ◽  
Sharp Decrease ◽  
Acid Invertase ◽  
Leaf Damage ◽  
Rapid Changes ◽  
Per Se ◽  
Carbohydrate Levels ◽  
Chicory Roots

Large-scale inulin production from chicory roots (Cichorium intybus L.) is hampered by the induction of 1-FEH activity (fructan 1-exohydrolase) and concomitant fructose production in autumn, coincident with a period with low night temperatures that cause leaf damage. To understand whether leaf damage per se is sufficient for 1-FEH induction and fructan breakdown, we defoliated mature chicory plants at a preharvest stage (September 10) and investigated the changes in carbohydrate levels and 1-FEH activities. Also, the activities of 1-SST (sucrose:sucrose 1-fructosyl transferase, EC 2.4.1.99), 1-FFT (fructan:fructan 1-fructosyl transferase, EC 2.4.1.100), and acid invertase (EC 3.2.1.26) were determined. Defoliation did not result in a prompt fructan breakdown and increase in 1-FEH activity, but after 10 days fructan breakdown and 1-FEH activities became higher in the defoliated plants. Defoliation resulted in a sharp decrease in 1-SST activity over the first 24 h. Afterwards, root 1-SST activities of defoliated plants remained at a lower level than in control plants. 1-FFT and invertase activities were not affected by defoliation. It can be concluded that defoliation of plants at the preharvest stage by itself did not induce the same rapid changes as observed in naturally induced October roots by low temperature (harvest stage). Taken together with our finding that 1-FEH is not induced in chicory roots when plants are transferred to the greenhouse early autumn (minimal temperature 14°C), we conclude that low temperatures might be essential for 1-FEH induction.

scholarly journals Quantum thermodynamics at low temperatures

2021 ◽  
Vol 52 (3) ◽  
pp. 15-17
Author(s):  
Jukka P. Pekola
Keyword(s):  
Quantum Information ◽  
Low Temperature ◽  
Low Temperatures ◽  
Quantum Information Processing ◽  
Quantum Systems ◽  
Quantum Thermodynamics ◽  
Heat Engines ◽  
Per Se ◽  
Working Media ◽  
Quantum Heat Engines

Low temperature phenomena and methods are quantum thermodynamics per se. Modern engineered quantum systems, for instance those used for superconducting quantum information processing and mesoscopic electron transport, provide working media for realizing devices such as quantum heat engines and refrigerators and a testbed for fundamental principles and phenomena in thermodynamics of quantum systems and processes.

Investigation of Impeller Strength for a Cryogenic Liquid Turbine

2010 ◽  
Author(s):  
Yan Ren ◽  
Jinju Sun ◽  
Rongye Zheng ◽  
Peng Song ◽  
Ke Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Centrifugal Force ◽  
Low Temperatures ◽  
Large Scale ◽  
Cryogenic Liquid ◽  
Air Separation ◽  
Design Flow ◽  
Navier Stokes Equation ◽  
Separation Unit

A single stage cryogenic liquid turbine is designed for a large-scale internal compression air-separation unit to replace the Joule-Thompson valve and recover energy from the liquefied air during throttling process. It includes a 3-dimensional impeller, variable geometry nozzle, and asymmetrical volute. Strength evaluation of such a liquid turbine is both essential and complicated, which involves a proper evaluation of stress acting on the components and mechanical property of the chosen materials at low temperature. For metals under low temperatures, brittle fracture of the metal may occur prior to fatigue damage. A comprehensive consideration of low-temperature mechanical properties of materials and mechanical loads (due to hydrodynamic force and centrifugal force) acting on the components is of particular importance. Aluminum alloy 2031 is used for the turbine impeller and its mechanical properties under low temperatures are analyzed. To evaluate the stress acting on the components, numerical investigation using 3-D incompressible Navier-Stokes Equation together with k-epsilon turbulence model and mixing plane approach at rotator-stator interface are carried out at design and off-design flow with different nozzle-vane settings. The obtained pressure force is transformed into hydrodynamic load acting on the solid surface by means of fluid-solid interaction technology, and then used in the FEM (Finite Element Method) structure analysis together with the centrifugal force. Stress distribution of the component is obtained and deformation of the component analyzed. Evaluation of impeller strength is conducted for the cryogenic liquid turbine by combining the foregoing two aspects, and a use of alloy 2031 for the turbine expander is validated.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

scholarly journals Sustainable Large-Scale Aquaculture of the Northern Hemisphere Sea Lettuce, Ulva fenestrata, in an Off-Shore Seafarm

2021 ◽  
Vol 9 (6) ◽  
pp. 615
Author(s):  
Sophie Steinhagen ◽  
Swantje Enge ◽  
Karin Larsson ◽  
Joakim Olsson ◽  
Göran M. Nylund ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Low Temperature ◽  
Northern Hemisphere ◽  
Biochemical Composition ◽  
Large Scale ◽  
Biomass Yield ◽  
Phenolic Content ◽  
Seedling Density ◽  
Ulva Fenestrata ◽  
High Nutrient

The growing world population demands an increase in sustainable resources for biorefining. The opening of new farm grounds and the cultivation of extractive species, such as marine seaweeds, increases worldwide, aiming to provide renewable biomass for food and non-food applications. The potential for European large-scale open ocean farming of the commercial green seaweed crop Ulva is not yet fully realized. Here we conducted manipulative cultivation experiments in order to investigate the effects of hatchery temperature (10 and 15 °C), nutrient addition (PES and 3xPES) and swarmer density (500 and 10,000 swarmers ml−1) on the biomass yield and biochemical composition (fatty acid, protein, carbohydrate, pigment and phenolic content) of off-shore cultivated Ulva fenestrata in a Swedish seafarm. High seedling densities were optimal for the growth of this northern hemisphere crop strain and significantly increased the mean biomass yield by ~84% compared to low seedling densities. Variations of nutrients or changes in temperature levels during the hatchery phase were not necessary to increase the subsequent growth in an open-water seafarm, however effects of the factors on the thallus habitus (thallus length/width) were observed. We found no significant effect of the environmental factors applied in the hatchery on the total fatty acid or crude protein content in the off-shore cultivated Ulva. However, low seedling density and low temperature increased the total carbohydrate content and furthermore, high temperature in combination with high nutrient levels decreased the pigment content (chlorophyll a, b, carotenoids). Low temperature in combination with high nutrient levels increased the phenolic content. Our study confirms the successful and sustainable potential for large-scale off-shore cultivation of the Scandinavian crop U. fenestrata. We conclude that high seedling density in the hatchery is most important for increasing the total biomass yield of sea-farmed U. fenestrata, and that changing temperature or addition of nutrients overall does not have a large effect on the biochemical composition. To summarize, our study contributes novel insights into the large-scale off-shore cultivation potential of northern hemisphere U. fenestrata and underpins suitable pre-treatments during the hatchery phase of seedlings to facilitate a successful and cost-efficient large-scale rope cultivation.

FEC-LiTFSI-Pyr1ATFSI Ionic Liquid Electrolyte to Improve Low Temperature Performance of Lithium-Ion Batteries

2014 ◽  
Vol 986-987 ◽  
pp. 80-83
Author(s):  
Xiao Xue Zhang ◽  
Zhen Feng Wang ◽  
Cui Hua Li ◽  
Jian Hong Liu ◽  
Qian Ling Zhang
Keyword(s):  
Low Temperature ◽  
Lithium Ion Batteries ◽  
Low Temperatures ◽  
Freezing Point ◽  
Lithium Ion ◽  
Liquid Electrolyte ◽  
Capacity Retention ◽  
Composite Electrolyte ◽  
Ionic Liquid Electrolyte ◽  
Fluoroethylene Carbonate

N-methyl-N-allylpyrrolidinium bis (trifluoromethanesulfonyl) imide (PYR1ATFSI) with substantial supercooling behavior is synthesized to develop low temperature electrolyte for lithium-ion batteries. Additive fluoroethylene carbonate (FEC) in LiTFSI/PYR1ATFSI/EC/PC/EMC is found that it can reduce the freezing point. LiFePO4/Li coin cells with the FEC-PYR1ATFSI electrolyte exhibit good capacity retention, reversible cycling behavior at low temperatures. The good performance can be attributed to the decrease in the freezing point and the polarization of the composite electrolyte.

Low Temperature Large Scale CVD Synthesis of Nano Onion-Like Fullerenes

2012 ◽  
Vol 490-495 ◽  
pp. 3211-3214 ◽  
Author(s):  
Lei Shan Chen ◽  
Cun Jing Wang
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Aluminum Hydroxide ◽  
Large Scale ◽  
Iron Catalyst ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Naoh Solution ◽  
Synthesis Reactions

Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

Anthracene fluorescence at low temperatures. I. Purified single crystals

1972 ◽  
Vol 25 (7) ◽  
pp. 1411 ◽  
Author(s):  
LE Lyons ◽  
LJ Warren
Keyword(s):  
Low Temperature ◽  
Single Crystals ◽  
Fluorescence Spectrum ◽  
Low Temperatures ◽  
Free Exciton ◽  
Deformation Bands ◽  
Exciton Emission ◽  
Polarized Emission ◽  
Impurity Bands ◽  
Phonon Structure

The low-temperature fluorescence spectrum of purified vapour-grown anthracene single crystals is presented and the free-exciton emission distinguished from a number of defect or impurity bands present even in the purest crystals. In assigning the observed bands the symmetry of the active vibrations and the origin of background fluorescence and deformation bands are discussed. The phonon structure in the region of the fluorescence origin was found to be almost completely b-polarized. Emission of electronic origin (25103 cm-1) was too weak to be observed. Polarization ratios of the principal vibronio bands at 5.6 K are given.

Desiccation and low temperature attenuate the effect of UVC254 nm in the photobiont of the astrobiologically relevant lichens Circinaria gyrosa and Buellia frigida

2014 ◽  
Vol 14 (3) ◽  
pp. 479-488 ◽  
Author(s):  
T. Backhaus ◽  
R. de la Torre ◽  
K. Lyhme ◽  
J.-P. de Vera ◽  
J. Meeßen
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Photosynthetic Activity ◽  
Real Space ◽  
Fast Recovery ◽  
Protective Mechanisms ◽  
Subzero Temperatures ◽  
High Viability ◽  
Buellia Frigida ◽  
Insight Into

AbstractSeveral investigations on lichen photobionts (PBs) after exposure to simulated or real-space parameters consistently reported high viability and recovery of photosynthetic activity. These studies focused on PBs within lichen thalli, mostly exposed in a metabolically inactive state. In contrast, a recent study exposed isolated and metabolically active PBs to the non-terrestrial stressor UVC254 nm and found strong impairment of photosynthetic activity and photo-protective mechanisms (Meeßen et al. in 2014b). Under space and Mars conditions, UVC is accompanied by other stressors as extreme desiccation and low temperatures. The present study exposed the PBs of Buellia frigida and Circinaria gyrosa, to UVC in combination with desiccation and subzero temperatures to gain better insight into the combined stressors' effect and the PBs' inherent potential of resistance. These effects were examined by chlorophyll a fluorescence which is a good indicator of photosynthetic activity (Lüttge & Büdel in 2010) and widely used to test the viability of PBs after (simulated) space exposure. The present results reveal fast recovery of photosynthetic activity after desiccation and subzero temperatures. Moreover, they demonstrate that desiccation and cold confer an additional protective effect on the investigated PBs and attenuate the PBs' reaction to another stressor – even if it is a non-terrestrial one such as UVC. Besides other protective mechanisms (anhydrobiosis, morphological–anatomical traits and secondary lichen compounds), these findings may help to explain the high resistance of lichens observed in astrobiological studies.

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