Forced and Natural Convective Drying of Trehalose/Water Thin Films: Implication in the Desiccation Preservation of Mammalian Cells

2006 ◽  
Vol 128 (3) ◽  
pp. 335-346 ◽  
Author(s):  
Bingyan Chen ◽  
Alex Fowler ◽  
Sankha Bhowmick
Keyword(s):  
Thin Films ◽  
Membrane Permeability ◽  
Water Transport ◽  
Mammalian Cells ◽  
Water Solution ◽  
Glassy State ◽  
Convective Drying ◽  
Glassy Matrix ◽  
Drying Time ◽  
Order Of Magnitude

Trehalose is believed to offer desiccation protection to mammalian cells by forming stable glassy matrices. The goal of the current study was to explore the desiccation kinetics of thin films of trehalose-water solution under forced and natural convective conditions and to investigate the thermophysical state of mammalian cells at the bottom of the thin film. We developed a finite difference model based on the mass and energy conservation equations coupled to the water transport model from the cells. The boundary conditions were obtained from correlations or experimental measurements and the Gordon-Taylor equation was used to predict the glass transition temperature at every location. Results indicated that there are three distinct regimes for drying for both forced and natural convection, characterized by the slope of the moisture content plot as a function of time. Our results also indicate that the surface of the solution reached the glassy state in less than 10min for the Reynolds (forced) numbers explored and ∼30min for some Rayleigh (natural convective) numbers; however, significant water was trapped at this instant. Larger drying force hastened quicker glass formation but trapped more water. The numerical model was capable of predicting the drying kinetics for the dilute region accurately, but deviated while predicting the other regimes. Based on these experimental validations of the model, the osmotic response of different cells located at the bottom of the solution with orders of magnitude difference in their membrane permeability (Lp) was predicted. The results suggested that extracellular glass formed around cells at the bottom of a trehalose-water solution by the propagation of glass into the solution; however it takes more than an order of magnitude time (∼7minto>100min for forced convective drying) to remove sufficient water to form glass around cells from the time when the first surface glass is formed. This is attributed to low diffusivity of water through the glass. In addition, the water transport from the glassy matrix could be either diffusion or Lp limited. For diffusion-limited transport, lowering the film thickness at the beginning of drying by half almost lowers the drying time by an order of magnitude. In summary, the optimal design of convective desiccation protocols requires accounting for the size of the cell, their membrane permeability (Lp) and the starting thickness of the solution.

scholarly journals Energetic and exergetic analysis of a convective drier: A case study of potato drying process

2020 ◽  
Vol 5 (1) ◽  
pp. 563-572
Author(s):  
Iman Golpour ◽  
Mohammad Kaveh ◽  
Reza Amiri Chayjan ◽  
Raquel P. F. Guiné
Keyword(s):  
Energy Consumption ◽  
Research Work ◽  
Specific Energy Consumption ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Energy Utilization ◽  
Convective Drying ◽  
Drying Time ◽  
Energy And Exergy ◽  
Exergy Losses

AbstractThis research work focused on the evaluation of energy and exergy in the convective drying of potato slices. Experiments were conducted at four air temperatures (40, 50, 60 and 70°C) and three air velocities (0.5, 1.0 and 1.5 m/s) in a convective dryer, with circulating heated air. Freshly harvested potatoes with initial moisture content (MC) of 79.9% wet basis were used in this research. The influence of temperature and air velocity was investigated in terms of energy and exergy (energy utilization [EU], energy utilization ratio [EUR], exergy losses and exergy efficiency). The calculations for energy and exergy were based on the first and second laws of thermodynamics. Results indicated that EU, EUR and exergy losses decreased along drying time, while exergy efficiency increased. The specific energy consumption (SEC) varied from 1.94 × 105 to 3.14 × 105 kJ/kg. The exergy loss varied in the range of 0.006 to 0.036 kJ/s and the maximum exergy efficiency obtained was 85.85% at 70°C and 0.5 m/s, while minimum exergy efficiency was 57.07% at 40°C and 1.5 m/s. Moreover, the values of exergetic improvement potential (IP) rate changed between 0.0016 and 0.0046 kJ/s and the highest value occurred for drying at 70°C and 1.5 m/s, whereas the lowest value was for 70°C and 0.5 m/s. As a result, this knowledge will allow the optimization of convective dryers, when operating for the drying of this food product or others, as well as choosing the most appropriate operating conditions that cause the reduction of energy consumption, irreversibilities and losses in the industrial convective drying processes.

Structure and Conductivity of Iodine-Doped C60 Thin Films

1994 ◽  
Vol 359 ◽  
Author(s):  
Jun Chen ◽  
Haiyan Zhang ◽  
Baoqiong Chen ◽  
Shaoqi Peng ◽  
Ning Ke ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Room Temperature ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Thermally Activated ◽  
Order Of Magnitude

ABSTRACTWe report here the results of our study on the properties of iodine-doped C60 thin films by IR and optical absorption, X-ray diffraction, and electrical conductivity measurements. The results show that there is no apparent structural change in the iodine-doped samples at room temperature in comparison with that of the undoped films. However, in the electrical conductivity measurements, an increase of more that one order of magnitude in the room temperature conductivity has been observed in the iodine-doped samples. In addition, while the conductivity of the undoped films shows thermally activated temperature dependence, the conductivity of the iodine-doped films was found to be constant over a fairly wide temperature range (from 20°C to 70°C) exhibiting a metallic feature.

Evaluation of Sub-Gap States in Amorphous In-Ga-Zn-O Thin Films Treated with Various Process Conditions

2014 ◽  
Vol 1633 ◽  
pp. 55-60 ◽  
Author(s):  
Kazushi Hayashi ◽  
Aya Hino ◽  
Hiroaki Tao ◽  
Yasuyuki Takanashi ◽  
Shinya Morita ◽  
...  
Keyword(s):  
Thin Films ◽  
Peak Position ◽  
Process Conditions ◽  
Charge Densities ◽  
Capacitance Voltage ◽  
Time Regime ◽  
Order Of Magnitude ◽  
Transient Spectroscopy ◽  
Gap States ◽  
Capacitance Transient

ABSTRACTIn the present study, the sub-gap states of amorphous In-Ga-Zn-O (a-IGZO) thin films treated with various process conditions have been evaluated by means of capacitance-voltage (C-V) characteristics and isothermal capacitance transient spectroscopy (ICTS). It was found that the space-charge densities of the a-IGZO decreased as the oxygen partial pressure was increased during the sputtering of a-IGZO thin films. The ICTS spectra for the 4, 8, and 12 % samples were similar and the peak positions were found to be around 1 × 10-2 s at 180 K. On the other hand, the peak position for the 20 % sample shifted to a longer time regime and was located at around 2 × 10-1 s at 180 K. The total densities of the traps for the 4, 8, and 12 % samples were calculated to be 5−6 × 1016 cm-3, while that for 20 % was one order of magnitude lower than the others. From Thermal desorption spectrometer, it was found that desorption of Zn atoms started at a temperature higher than 300 °C for the 4 % sample, while desorption of Zn was not observed for the 20 % sample. The introduction of the sub-gap states could be attributed to oxygen-rich and/or Zn-deficient defects in the a-IGZO thin films formed during thermal annealing.

Method of calculating the convective drying time for gypsum molds

1989 ◽  
Vol 46 (11) ◽  
pp. 456-459
Author(s):  
Yu. N. Kryuchkov ◽  
G. Z. Komskii
Keyword(s):  
Convective Drying ◽  
Drying Time

scholarly journals Convective Drying of Sewage Sludge Layer in Through-flow

2020 ◽  
Vol 66 (9) ◽  
pp. 481-493
Author(s):  
Andraž Lipolt ◽  
Brane Širok ◽  
Marko Hočevar ◽  
Lovrenc Novak
Keyword(s):  
Sewage Sludge ◽  
Drag Force ◽  
Layer Structure ◽  
Measured Data ◽  
Matter Content ◽  
Convective Drying ◽  
Coefficient Of Determination ◽  
Dry Matter Content ◽  
Drying Time ◽  
Drying Rates

Drying of the sewage sludge layer was investigated in a convective laboratory dryer at air temperatures of 65 °C and 80 °C and air speeds of 0.53 m/s and 0.83 m/s. The sludge layer was formed by loading cylindrical extrudates on a grate of 0.5 m × 0.5 m size. The drying air was directed through the layer, as typically encountered in industrial belt dryers. Under such setup, the sludge layer structure and porosity significantly affect the air flow conditions and thus the drying rates. Shrinkage and cracking of the material during drying caused changes in the layer’s porous structure, that affected the pressure drop and the drag force due to passing of air through the layer. The decreasing of drag force over time was modeled by a simple function that showed excellent agreement to the selected measured data. The sludge layer drying kinetics was determined by fitting the measured data to the most common drying models. Two models, the modified Nadhari and the Wang Singh model, were determined as most suitable for modeling of drying curves. The total drying time per kilogram of sludge was modeled as a function of drying air temperature, drying air velocity and initial sludge dry matter content. The coefficient of determination (R2) of the model is 0.944. Total drying times between 43 minutes per kilogram and 76 minutes per kilogram of sludge were obtained for the investigated range of drying air conditions.

scholarly journals The influence of ethanol on the convective drying and on the nutritional quality of dekopon slices

2018 ◽  
Author(s):  
Ronaldo Elias de Mello-Júnior ◽  
Nathane Silva Resende ◽  
Jefferson Luiz Gomes Corrêa ◽  
Leila Aparecida Salles Pio ◽  
Elisângela Elena Nunes Carvalho
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Vitamin C ◽  
Nutritional Quality ◽  
Quality Parameters ◽  
Nutritional Composition ◽  
Convective Drying ◽  
Total Phenolic ◽  
Drying Time ◽  
Citrus Reticulate

Dekopon or Hallabong (Citrus reticulate “Shiranui”) is a hybrid fruit that belongs to the citrus fruits. The scientific and commercial interests in dekopon is due to its nutritional composition. The objective of the study was to verify the influence of ethanol as a pretreatment in reducing drying time as well as maintaining nutritional quality (vitamin C, total phenolic compounds, and antioxidant activity) of dekopon slices. The drying with ethanol at 70 °C promoted the greatest reduction in drying time, but the processed pretreated samples at 50 °C presented the highest level of nutritional quality parameters. Keywords: drying time; vitamin C; phenolic compounds; antioxidant activity 

scholarly journals Mathematical modeling of pequi pulp drying and effective diffusivity determination

2017 ◽  
Vol 21 (7) ◽  
pp. 493-498 ◽  
Author(s):  
Elisabete P. de Sousa ◽  
Rossana M. F. de Figueirêdo ◽  
Josivanda P. Gomes ◽  
Alexandre J. de M. Queiroz ◽  
Deise S. de Castro ◽  
...  
Keyword(s):  
Experimental Data ◽  
Effective Diffusivity ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Drying Time ◽  
Air Speed ◽  
Drying Curves ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Best Fit

ABSTRACT The aim of this work was to study the drying kinetics of pequi pulp by convective drying at different conditions of temperature (50, 60, 70 and 80 °C) and thickness (0.5, 1.0 and 1.5 cm) at the air speed of 1.0 m s-1, with no addition of adjuvant. The experimental data of pequi pulp drying kinetics were used to plot drying curves and fitted to the models: Midilli, Page, Henderson & Pabis and Newton. Effective diffusivity was calculated using the Fick’s diffusion model for a flat plate. It was found that, with increasing thickness, the drying time increased and, with increasing temperature, the drying time was reduced. The Midilli model showed the best fit to the experimental data of pequi pulp drying at all temperatures and thicknesses, presenting higher coefficients of determination (R2), indicating that this model satisfactorily represents the pequi pulp drying phenomenon. There was a trend of increase in the effective diffusivity with the increase in pulp layer thickness and temperature.

scholarly journals Different electrode anodes used in OLED devices Diferentes eletrodos anodos usados em dispositivos OLEDs

2021 ◽  
Author(s):  
Emerson Roberto Santos ◽  
Thiago de Carvalho Fullenbach ◽  
Marina Sparvoli Medeiros ◽  
Luis da Silva Zambom ◽  
Roberto Koji Onmori ◽  
...  
Keyword(s):  
Thin Films ◽  
Tin Oxide ◽  
Threshold Voltage ◽  
Indium Tin Oxide ◽  
Light Emitting Diode ◽  
Electrical Current ◽  
High Threshold ◽  
Diamond Coatings ◽  
Ito Thin Films ◽  
Order Of Magnitude

Transparent conductive oxides (TCOs) known as indium tin oxide (ITO) and fluorine tin oxide (FTO) deposited on glass were compared by different techniques and also as anodes in organic light-emitting diode (OLED) devices with same structure. ITO produced at laboratory was compared with the commercial one manufactured by different companies: Diamond Coatings, Displaytech and Sigma-Aldrich, and FTO produced at laboratory was compared with the commercial one manufactured by Flexitec Company. FTO thin films produced at laboratory presented the lowest performance measured by Hall effect technique and also by I-V curve of OLED device with low electrical current and high threshold voltage. ITO thin films produced at laboratory presented elevated sheet resistance in comparison with commercial ITOs (approximately one order of magnitude greater), that can be related by a high number of defects as discontinuity of the chemical lattice or low crystalline structure. In the assembly of OLED devices with ITO and FTO produced at laboratory, neither presented luminances. ITO manufactured by Sigma-Aldrich company presented better electrical and optical characteristics, as low electrical resistivity, good wettability, favorable transmittance, perfect physicalchemical stability and lowest threshold voltage (from 3 to 4.5 V) for OLED devices.

Enhanced Evaporation of Microscale Droplets With an Infrared Laser

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Luis A. Ferraz-Albani ◽  
Alberto Baldelli ◽  
Chrissy J. Knapp ◽  
Wolfgang Jäger ◽  
Reinhard Vehring ◽  
...  
Keyword(s):  
Water Droplet ◽  
Droplet Evaporation ◽  
Radiant Flux ◽  
Droplet Temperature ◽  
Ambient Conditions ◽  
Drying Time ◽  
Proposed Model ◽  
Environment Temperature ◽  
Order Of Magnitude ◽  
Surface Area Change

Enhancement of water droplet evaporation by added infrared radiation was modeled and studied experimentally in a vertical laminar flow channel. Experiments were conducted on droplets with nominal initial diameters of 50 μm in air with relative humidities ranging from 0% to 90% RH. A 2800 nm laser was used with radiant flux densities as high as 4 × 105 W/m2. Droplet size as a function of time was measured by a shadowgraph technique. The model assumed quasi-steady behavior, a low Biot number liquid phase, and constant gas–vapor phase material properties, while the experimental results were required for model validation and calibration. For radiant flux densities less than 104 W/m2, droplet evaporation rates remained essentially constant over their full evaporation, but at rates up to 10% higher than for the no radiation case. At higher radiant flux density, the surface-area change with time became progressively more nonlinear, indicating that the radiation had diminished effects on evaporation as the size of the droplets decreased. The drying time for a 50 μm water droplet was an order of magnitude faster when comparing the 106 W/m2 case to the no radiation case. The model was used to estimate the droplet temperature. Between 104 and 5 × 105 W/m2, the droplet temperature changed from being below to above the environment temperature. Thus, the direction of conduction between the droplet and the environment also changed. The proposed model was able to predict the changing evaporation rates for droplets exposed to radiation for ambient conditions varying from dry air to 90% relative humidity.

Micropatterning of Mammalian Cells on Plasma Polymerized Polypyrrole Thin Films

2021 ◽  
Vol 49 (8) ◽  
pp. 2428-2434
Author(s):  
Chien-Hung Kuo ◽  
Yueh-Han Huang ◽  
Wen-Pin Lin ◽  
Tsung-Jen Wang ◽  
Meng-Jiy Wang
Keyword(s):  
Thin Films ◽  
Mammalian Cells
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