Relation between freezing temperature and length of conifer needles

1968 ◽  
Vol 46 (10) ◽  
pp. 1211-1213 ◽  
Author(s):  
Shosuke Kaku ◽  
R.W. Salt
Keyword(s):  
Water Content ◽  
Cell Walls ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Nucleation Temperature ◽  
Nucleation Sites ◽  
Conifer Needles ◽  
Increasing Function

The relationships between freezing temperature (or supercooling) and length, weight, and water content of Pinus and Cedrus needles were investigated. Freezing temperature was an increasing function of each of these three variables. When Pinus needles were cut proximally to uniform length (50 mm), supercooling was unaffected by either weight or water content. Thus, ice nucleation temperature was an increasing function of the length of needles, or, more precisely, of the length of the stele, or, still more precisely, of the number of water-conducting capillary units contributing to that length, but ultimately of the number and quality of favorable nucleation sites contained therein. It is suggested that nucleation takes place at sites associated with the cell walls and not on nucleators suspended in the water.

Location and quantitative aspects of ice nucleators in insects

1968 ◽  
Vol 46 (3) ◽  
pp. 329-333 ◽  
Author(s):  
R. W. Salt
Keyword(s):  
Freezing Temperature ◽  
Ice Nucleation ◽  
Gut Contents ◽  
Aqueous Systems ◽  
Nucleation Sites ◽  
Ice Nucleators

Gut contents are the source of ice nucleation in feeding insects; in those non-feeding forms where it has been possible to observe nucleation, residual food within the gut has been the source. When freezing is confined to tissues with no digestive elements, such as excised appendages, preferred nucleation sites may be observed but the tissues or structures involved have not been identified. Haemolymph and intracellular matter are improbable as functional nucleating sites, reducing the anatomical possibilities greatly.Isolated appendages were also used to demonstrate that the relation between freezing temperature and mass in aqueous systems is more accurately defined by the numbers or other quantitative aspects of nucleators than by the mass of water.

scholarly journals Ice nucleation efficiency of clay minerals in the immersion mode

2012 ◽  
Vol 12 (1) ◽  
pp. 3213-3261 ◽  
Author(s):  
V. Pinti ◽  
C. Marcolli ◽  
B. Zobrist ◽  
C. R. Hoyle ◽  
T. Peter
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Acid Treatment ◽  
Pure Water ◽  
Source Region ◽  
Freezing Temperature ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Nucleation Sites ◽  
Mineral Society

Abstract. Emulsion and bulk freezing experiments were performed to investigate immersion ice nucleation on clay minerals in pure water, using various kaolinites, montmorillonites, illites as well as natural dust from the Hoggar Mountains in the Saharan region. DSC (differential scanning calorimeter) measurements were performed on the kaolinites KGa-1b and KGa-2 from the Clay Mineral Society and kaolinite from Sigma-Aldrich; the montmorillonites SWy-2 and STx-1b from the Clay Mineral Society and the acid treated montmorillonites KSF and K-10 from Sigma Aldrich; the illites NX and SE from Arginotec. The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to two distinct heterogeneous freezing peaks, which suggest the presence of a low number of qualitatively distinct average nucleation site classes. We refer to the peak at the lowest temperature as "standard peak" and to the one at higher temperatures as "special peak". Conversely, freezing in bulk samples is not initiated by the average nucleation sites, but by a very low number of "best sites". The kaolinites showed quite narrow standard peaks with onset temperatures 239 K < Tonstd < 242 K and best sites with averaged median freezing temperature Tmedbest = 257 K. Only the kaolinite from Sigma Aldrich featured a special peak with freezing onset at 248 K. The illites showed broad standard peaks with freezing onsets at 244 K < Tonstd < 246 K and best sites with averaged median freezing temperature Tmedbest = 262 K. Montmorillonites had standard peaks with onsets 238 K < Tonstd < 240 K and best sites with Tmedbest=257 K. SWy-2, M K10, and KSF featured special peaks with onsets at Tonspcl=247, 240, and 242 K, respectively. M K10 and KSF both from Sigma Aldrich had less intense standard peaks compared to the ones from the Clay Mineral Society suggesting that a fraction of the standard sites are lost by the acid treatment. The acid treatment had however, no evident effect on best sites. Our investigations demonstrate that immersion freezing temperatures of clay minerals strongly depend on the amount of clay mineral present per droplet and on the exact type (location of collection and pre-treatment) of the clay mineral. We suggest that apparently contradictory results obtained by different groups with different setups can indeed be brought into good agreement when only clay minerals of the same type and amount per droplet are compared. The natural sample from the Hoggar Mountains, a region whose dusts have been shown to be composed mainly of illite, showed very similar freezing characteristics to the illites with freezing peak onsets 247 K < Tonstd < 248 K for the average and Tmedbest = 261 K for the best sites. Relating the concentration of best IN to the dust concentration in the atmosphere suggested that the best IN in the Hoggar sample would be common enough downwind of their source region to account for ambient IN number densities in the temperature range of 250–260 K at least during dust events.

scholarly journals Generalisation of Levine's prediction for the distribution of freezing temperatures of droplets: a general singular model for ice nucleation

2013 ◽  
Vol 13 (14) ◽  
pp. 7215-7223 ◽  
Author(s):  
R. P. Sear
Keyword(s):  
Extreme Value Distribution ◽  
Freezing Temperature ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Maximum Value ◽  
Nucleation Sites ◽  
Explicit Time Dependence ◽  
Freezing Temperatures

Abstract. Models without an explicit time dependence, called singular models, are widely used for fitting the distribution of temperatures at which water droplets freeze. In 1950 Levine developed the original singular model. His key assumption was that each droplet contained many nucleation sites, and that freezing occurred due to the nucleation site with the highest freezing temperature. The fact that freezing occurs due to the maximum value out of a large number of nucleation temperatures, means that we can apply the results of what is called extreme-value statistics. This is the statistics of the extreme, i.e. maximum or minimum, value of a large number of random variables. Here we use the results of extreme-value statistics to show that we can generalise Levine's model to produce the most general singular model possible. We show that when a singular model is a good approximation, the distribution of freezing temperatures should always be given by what is called the generalised extreme-value distribution. In addition, we also show that the distribution of freezing temperatures for droplets of one size, can be used to make predictions for the scaling of the median nucleation temperature with droplet size, and vice versa.

scholarly journals Generalisation of Levine's prediction for the distribution of freezing temperatures of droplets: a general singular model for ice nucleation

2013 ◽  
Vol 13 (4) ◽  
pp. 10499-10520 ◽  
Author(s):  
R. P. Sear
Keyword(s):  
Extreme Value Distribution ◽  
Freezing Temperature ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Maximum Value ◽  
Nucleation Sites ◽  
Explicit Time Dependence ◽  
Freezing Temperatures

Abstract. Models without an explicit time dependence, called singular models, are widely used for fitting the distribution of temperatures at which water droplets freeze. In 1950 Levine developed the original singular model. His key assumption was that each droplet contained many nucleation sites, and that freezing occurred due to the nucleation site with the highest freezing temperature. The fact that freezing occurs due to the maximum value out of large number of nucleation temperatures, means that we can apply the results of what is called extreme-value statistics. This is the statistics of the extreme, i.e., maximum or minimum, value of a large number of random variables. Here we use the results of extreme-value statistics to show that we can generalise Levine's model to produce the most general singular model possible. We show that when a singular model is a good approximation, the distribution of freezing temperatures should always be given by what is called the generalised extreme-value distribution. In addition, we also show that the distribution of freezing temperatures for droplets of one size, can be used to make predictions for the scaling of the median nucleation temperature with droplet size, and vice versa.

Influence of Freeze-Drying Modes on the Quality of Live Plague Vaccine

2019 ◽  
Vol 35 (4) ◽  
pp. 73-78
Author(s):  
S.E. Gostischeva ◽  
D.V. Rostovtseva ◽  
G.F. Ivanova ◽  
A.V. Kostrominov ◽  
M.V. Pilipenko
Keyword(s):  
Heating Rate ◽  
Freeze Drying ◽  
Eutectic Point ◽  
Freezing Temperature ◽  
Freezing Time ◽  
Residual Moisture ◽  
High Viability ◽  
Plague Vaccine ◽  
Selection Of

The optimization of the drying schedule has been carried out to improve the quality indicators of the live plague vaccine. Based on the data obtained on the eutectic point of the vaccine suspension, the freezing temperature and freezing time were set to -50 °С and 6-7 h, respectively. A pressure of 40 mTorr over the surface of the drying suspension and 20 mTorr during the desorption were shown to be the best conditions for sublimation. The drying tests with different options for the shelf heating rate, vacuum depth and duration of intermediate temperature indicators were carried out to develop the improved freeze-drying mode providing the selection of the most adapted bacteria. A vaccine lyophilized under the developed conditions has low residual moisture (up to 2%) and high viability index that persists over the whole shelf life. lyophilization, sublimation, eutectic, live plague vaccine, residual moisture, viability

scholarly journals Plant Cell Wall Hydration and Plant Physiology: An Exploration of the Consequences of Direct Effects of Water Deficit on the Plant Cell Wall

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1263
Author(s):  
David Stuart Thompson ◽  
Azharul Islam
Keyword(s):  
Cell Wall ◽  
Water Content ◽  
Bacterial Cellulose ◽  
Plant Cell ◽  
Cell Walls ◽  
Plant Cell Wall ◽  
Plant Cell Walls ◽  
Cell Wall Polysaccharides ◽  
Degree Of Hydration ◽  
Cellulose Composites

The extensibility of synthetic polymers is routinely modulated by the addition of lower molecular weight spacing molecules known as plasticizers, and there is some evidence that water may have similar effects on plant cell walls. Furthermore, it appears that changes in wall hydration could affect wall behavior to a degree that seems likely to have physiological consequences at water potentials that many plants would experience under field conditions. Osmotica large enough to be excluded from plant cell walls and bacterial cellulose composites with other cell wall polysaccharides were used to alter their water content and to demonstrate that the relationship between water potential and degree of hydration of these materials is affected by their composition. Additionally, it was found that expansins facilitate rehydration of bacterial cellulose and cellulose composites and cause swelling of plant cell wall fragments in suspension and that these responses are also affected by polysaccharide composition. Given these observations, it seems probable that plant environmental responses include measures to regulate cell wall water content or mitigate the consequences of changes in wall hydration and that it may be possible to exploit such mechanisms to improve crop resilience.

scholarly journals Effects of different drying rates on the physiological quality of Coffea canephora Pierre seeds

2005 ◽  
Vol 17 (2) ◽  
pp. 199-205 ◽  
Author(s):  
Sttela Dellyzete Veiga Franco da Rosa ◽  
Delacyr da Silva Brandão Júnior ◽  
Édila Vilela de Resende Von Pinho ◽  
André Delly Veiga ◽  
Luiz Hildebrando de Castro e Silva
Keyword(s):  
Water Content ◽  
Storage Temperature ◽  
Removal Rate ◽  
Coffea Canephora ◽  
Development Stage ◽  
Seed Vigor ◽  
Drying Rate ◽  
Physiological Quality ◽  
Drying Rates

Desiccation tolerance in seeds depends on the species, development stage and drying conditions, especially the water removal rate. Coffea seeds are considered of intermediate performance, because they tolerate relative dehydration compared to orthodox seeds and are sensitive to low temperatures. The objective of this study was to verify the effect of different drying rates on the viability and storability of Coffea canephora seeds. A complete randomized experimental design was used, in a factorial 3 x 5 x 2 design, with three drying rates (fast, intermediate and slow), five final mean water contents after drying (51, 42, 33, 22 and 15 %) and two storage temperatures (10 and 20°C). The germination and seed vigor assessments, using radicle protrusion, cotyledon leaf opening, seedling emergence and emergence speed index, were performed shortly after drying and after two and four months storage. It was observed that with reduction in the water content there was reduction in the germination values and seed vigor, for all the drying rates. The greatest reductions in physiological quality occurred when the seeds were dried quickly and the best results were obtained at the intermediate drying rate. There was an effect of drying rate and storage temperature on the physiological quality of the seeds, and lower germination and vigor values were observed in seeds with lower water content stored at 20°C. C. canephora seeds were tolerant to desiccation down to 15 % water content and can be stored for four months at 10°C. A temperature of 20ºC can be used to store C. canephora seeds, as long as the water content is not reduced to values below 22 % water content.

scholarly journals Penurunan mutu dan pendugaan umur simpan sup krim instan labu kuning diperkaya tempe untuk lansia dengan metode accelerated shelf life testing (ASLT)

2020 ◽  
Vol 8 (2) ◽  
pp. 134-142
Author(s):  
Salma Shafrina Aulia ◽  
Budi Setiawan ◽  
Tiurma Sinaga ◽  
Ahmad Sulaeman
Keyword(s):  
Lipid Oxidation ◽  
Shelf Life ◽  
Water Content ◽  
Water Activity ◽  
Critical Parameter ◽  
Storage Period ◽  
Life Testing ◽  
Quality Of Water ◽  
Long Time

Background: Instant pumpkin cream soup enriched with tempeh had fulfilled 10% Recommended Dietary Allowances (RDA) for elderly so that it can be used as an easy-to-serve snack, but decreasing quality of instant cream soup will be happened if the instant cream soup was stored for a long time. Objectives: This study aimed to analyze quality of water content, water activity and lipid oxidation in instant pumpkin cream soup during storage and estimated the shelf life of pumpkin cream soup enriched with tempeh.Method:  Quality storage was analyzed using of water content, water activity (aw) and lipid oxidation. Estimation of shelf life was analyzed using Arrhenius Accelerated Shelf Life Testing (ASLT) model.Results: The results showed that the water content, aw levels and lipid oxidation of instant pumpkin cream soup increased during the storage period. The critical parameter used in this study was lipid oxidation. Instant cream soup without the addition of tempeh can last 447 days  while the cream soup with the addition of tempeh has a shelf life of 433 days.Conclusion: Quality of instant pumpkin cream soup decreased during the storage period and it would be expired over a year.

scholarly journals Condensed-phase biogenic–anthropogenic interactions with implications for cold cloud formation

2017 ◽  
Vol 200 ◽  
pp. 165-194 ◽  
Author(s):  
Joseph C. Charnawskas ◽  
Peter A. Alpert ◽  
Andrew T. Lambe ◽  
Thomas Berkemeier ◽  
Rachel E. O’Brien ◽  
...  
Keyword(s):  
Freezing Temperature ◽  
Organic Aerosol ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Fossil Fuel Combustion ◽  
Soot Particles ◽  
Ice Nuclei ◽  
Deliquescence Relative Humidity ◽  
Homogeneous Freezing

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA–soot biogenic–anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (Tg) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibit a core–shell configuration (i.e.a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respectiveTgand FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.

scholarly journals Ice nucleation activity identified in some phytopathogenic Fusarium species

2005 ◽  
Vol 77 (2) ◽  
pp. 83-92 ◽  
Author(s):  
C. Richard ◽  
J.-G. Martin ◽  
S. Pouleur
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Species ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Free Living ◽  
Factors Affecting ◽  
Pure Cultures ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
Positive Controls

In order to know which species of Fusarium are ice nucleating and to determine the factors affecting their pathogenicity, ice nucleation activity (INA) was examined in Fusarium oxysporum, F. sporotrichioides, and F. tricinctum. Positive controls (lna+) used were F. acuminatum and F. avenaceum. The test for fungal INA was done with a simple and rapid tube nucleation assay. Twelve out of the 42 F. oxysporum isolates, and 8 out of 14 F. tricinctum isolates were lna+. No INA was detected in F sporotrichioides. In this test the threshold freezing temperature tended to increase with culture age, reaching a peak of -1°C in a few samples, which is as high as the warmest INA reported for bacteria, and higher than the INA detected in pure cultures of free-living fungi, lichen fungi, lichen algae and cyanobacteria. This is the first report of INA for F oxysporum.

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