Thermal regelation of single particles and particle clusters in ice

Soft Matter ◽  
2021 ◽  
Author(s):  
Jiaxue You ◽  
Zhijun Wang ◽  
M. Grae Worster
Keyword(s):  
Temperature Gradient ◽  
Mathematical Models ◽  
Single Particles ◽  
Freezing Front ◽  
Constant Rate ◽  
Kinetics Of

We investigated kinetics of thermal regelation of single particles and particle clusters in a temperature gradient using experiments and mathematical models. We find that clusters migrate at a constant rate, while single particles accelerate towards the freezing front.

scholarly journals Mathematical models to describe the drying process of Moringa oleifera leaves in a convective-air dryer

2021 ◽  
Author(s):  
Kivaandra Dayaa Rao Ramarao ◽  
Zuliana Razali ◽  
Chandran Somasundram
Keyword(s):  
Activation Energy ◽  
Mathematical Models ◽  
Moringa Oleifera ◽  
Effective Diffusivity ◽  
Drying Process ◽  
Constant Rate ◽  
Rate Period ◽  
Moringa Oleifera Leaves ◽  
Air Dryer ◽  
Kinetics Of

Drying kinetics of Malaysian Moringa oleifera leaves was investigated using a convective-air dryer. The drying parameters were: temperature (40, 50, 60, 70 °C), air velocity (1.3 m s<sup>–1</sup>, 1.7 m s<sup>–1</sup>). The drying process took place in the falling rate period and there was an absence of a constant rate period in this experiment. Six mathematical models (Lewis, Henderson and Pabis, Wang and Singh, Peleg, Page, and logarithmic) were selected for the description of drying characteristics of the leaves. The Wang and Singh model was determined as the best model based on the highest overall coefficient determinant (R<sup>2</sup>) and the lowest overall root mean square error (RMSE). The effective diffusivity (D<sub>eff</sub><sub> </sub>) was also calculated which was in the range of 3.98 × 10<sup>–11</sup> m<sup>2</sup> s<sup>–1</sup> to 1.74 × 10<sup>–10</sup> m<sup>2</sup> s<sup>–1. </sup>An Arrhenius relation was constructed to determine the activation energy for the samples in the convective air dryer. The activation energy for M. oleifera leaves was 39.82 kJ mol<sup>–1</sup> and 33.13 kJ mol<sup>–1</sup> at drying velocities of 1.3 m s<sup>–1</sup> and 1.7 m s<sup>–1</sup>, respectively.

scholarly journals Kinetics of Anti-SARS-CoV-2 Antibody Responses 3 Months Post Complete Vaccination with BNT162b2; A Prospective Study in 283 Health Workers

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1942
Author(s):  
Evangelos Terpos ◽  
Ioannis P. Trougakos ◽  
Vangelis Karalis ◽  
Ioannis Ntanasis-Stathopoulos ◽  
Sentiljana Gumeni ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Health Workers ◽  
Antibody Responses ◽  
Healthy Individuals ◽  
Younger Age ◽  
Constant Rate ◽  
Rate Of Decline ◽  
A Prospective Study ◽  
Kinetics Of ◽  
Over Time

The aim of this study was to investigate the kinetics of neutralizing antibodies (NAbs) and anti-SARS-CoV-2 anti-S-RBD IgGs up to three months after the second vaccination dose with the BNT162b2 mRNA vaccine. NAbs and anti-S-RBD levels were measured on days 1 (before the first vaccine shot), 8, 22 (before the second shot), 36, 50, and three months after the second vaccination (D111) (NCT04743388). 283 health workers were included in this study. NAbs showed a rapid increase from D8 to D36 at a constant rate of about 3% per day and reached a median (SD) of 97.2% (4.7) at D36. From D36 to D50, a slight decrease in NAbs values was detected and it became more prominent between D50 and D111 when the rate of decline was determined at −0.11 per day. The median (SD) NAbs value at D111 was 92.7% (11.8). A similar pattern was also observed for anti-S-RBD antibodies. Anti-S-RBDs showed a steeper increase during D22–D36 and a lower decline rate during D36–D111. Prior COVID-19 infection and younger age were associated with superior antibody responses over time. In conclusion, we found a persistent but declining anti-SARS-CoV-2 humoral immunity at 3 months following full vaccination with BNT162b2 in healthy individuals.

scholarly journals Drying Kinetics of Noni Seeds

2019 ◽  
Vol 11 (5) ◽  
pp. 250 ◽  
Author(s):  
Wellytton Darci Quequeto ◽  
Osvaldo Resende ◽  
Patrícia Cardoso Silva ◽  
Fábio Adriano Santos e Silva ◽  
Lígia Campos de Moura Silva
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Moisture Content ◽  
Mathematical Models ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Kinetics Of

Noni seeds have been used for years as an important medicinal source, with wide use in the pharmaceutical and food industry. Drying is a fundamental process in the post-harvest stages, where it enables the safe storage of the product. Therefore, the present study aimed to fit different mathematical models to experimental data of drying kinetics of noni seeds, determine the effective diffusion coefficient and obtain the activation energy for the process during drying under different conditions of air temperature. The experiment used noni seeds with initial moisture content of 0.46 (decimal, d.b.) and dehydrated up to equilibrium moisture content. Drying was conducted under different controlled conditions of temperature, 40; 50; 60; 70 and 80 &ordm;C and relative humidity, 24.4; 16.0; 9.9; 5.7 and 3.3%, respectively. Eleven mathematical models were fitted to the experimental data. The parameters to evaluate the fitting of the mathematical models were mean relative error (P), mean estimated error (SE), coefficient of determination (R2), Chi-square test (c2), Akaike Information Criterion (AIC) and Schwarz&rsquo;s Bayesian Information Criterion (BIC). Considering the fitting criteria, the model Two Terms was selected to describe the drying kinetics of noni seeds. Effective diffusion coefficient ranged from 8.70 to 23.71 &times; 10-10 m2 s-1 and its relationship with drying temperature can be described by the Arrhenius equation. The activation energy for noni seeds drying was 24.20 kJ mol-1 for the studied temperature range.

scholarly journals Estimation of anti-icing properties of coatings

2019 ◽  
Vol 135 ◽  
pp. 01009
Author(s):  
Valentina Loganina ◽  
Svetlana Kislitsyna
Keyword(s):  
Initial Period ◽  
Wetting Angle ◽  
Silicone Resin ◽  
Thermal Imager ◽  
Freezing Front ◽  
Properties Of Coatings ◽  
Metal Structures ◽  
Wetting Hysteresis ◽  
Inclined Surface ◽  
Kinetics Of

The proposed composition for anti-icing coating of metal structures. The composition contains as the filler used aerosil brand R 972 with a density of 2360 kg / m3, particle size of 16 nm and a specific surface 12000 m2 / kg. Silicone resin SILRES® MSE 100 with a 10% concentration was used as a binder. The degree of hydrophobicity was estimated by the value of the wetting angle. In order to characterize the anti-icing properties of the coatings, we used the static and dynamic (advancing and retreating) wetting angle, as well as wetting hysteresis, for which we measured the angles of leakage, and the angles of drift from. Studies of the dynamics of freezing drops on the surface were performed using a TESTO 875-1 thermal imager. It is shown, that the hysteresis of wetting of the superhydrophobic surface based on the developed composition is 3.7 degrees. The critical angle of rolling drops of water from an inclined surface is determined. In the study of the kinetics of freezing of a drop of water on a metal surface, an uneven distribution of temperature on the surface of a drop of water is observed. The process of freezing drops is multistage. In the initial period, there is a transfer of heat from the surface to a drop of water. This stage is followed by the process of freezing the drop, which is manifested in the movement of the freezing front from the substrate upwards.

Relaxation Processes in the Deformation of Unloaded Rubbers and the Influence of the Degree of Vulcanization

1951 ◽  
Vol 24 (4) ◽  
pp. 810-819
Author(s):  
B. A. Dogadkin ◽  
M. M. Reznikovskii˘
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Elastic Deformation ◽  
Relaxation Processes ◽  
Spatial Network ◽  
Relaxation Properties ◽  
Constant Rate ◽  
Different Temperatures ◽  
Kinetics Of

Abstract 1. It is shown that the process of stress relaxation at different initial elongations as well as the process of deformation at constant rate for unloaded rubbers at different temperatures (20–70° C) can be represented quantitatively by equations suggested in earlier works. Likewise the possibility of expanding the theories proposed for the kinetics of high-elastic deformation of spatial polymers is substantiated. 2. It is shown that the relaxation properties of soft unloaded vulcanizates of natural rubber and many synthetic rubbers do not undergo essential changes during vulcanization. 3. The conjecture is expressed that the invariability of the relaxation properties during vulcanization continues until the bonds of the spatial network are distributed sufficiently widely not to influence the activity or heat movement of the chain segments between them.

Evaluation of mathematical models to describe protein fraction degradation kinetics of various oilseed meals

2009 ◽  
Vol 2009 ◽  
pp. 171-171
Author(s):  
M Danesh Mesgaran ◽  
T Tashakkori ◽  
A Heravi Moussavi ◽  
S Danesh Mesgaran ◽  
A Vakili ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Goodness Of Fit ◽  
Degradation Kinetics ◽  
Direct Method ◽  
Rapeseed Meal ◽  
Insoluble Protein ◽  
Degradation Kinetic ◽  
Negative Exponential ◽  
Kinetics Of

In situ procedure is a direct method of measuring the rumen degradation kinetic of a feed nutrient. Data obtained by this technique are generally analysed using an exponential curve (Ørskov and McDonald, 1979). However, very low attention has been paid to choice of mathematical model to fit the curves and goodness-of-fit of the model. Lopez et al. (1999) pointed out that the disappearance of some feed components, particularly structural carbohydrates, exhibits a larger variety of forms than for crude protein (CP). In the present study, two different mathematical models of a straight line or a negative exponential (France et al., 1990; and Ørskov and McDonald, 1979) were selected to evaluate in situ degradation kinetics of protein fractions including true protein (TP), neutral-detergent insoluble protein (NDIP) and acid-detergent insoluble protein (ADIP) of various oilseed meals (cottonseed meal (CSM), soyabean meal (SM) and rapeseed meal (RM)).

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