scholarly journals Image Segmentation and 3D reconstruction for improved prediction of the sublimation rate during freeze drying

2018 ◽  
Author(s):  
Antonello A Barresi ◽  
Luigi C Capozzi ◽  
Andrea Arsiccio ◽  
Amelia C Sparavigna ◽  
Roberto Pisano
Keyword(s):  
Image Segmentation ◽  
3D Reconstruction ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Freeze Drying ◽  
3D Structure ◽  
Drying Process ◽  
Sublimation Rate ◽  
Sem Images ◽  
Pore Analysis

In a freeze drying process, the freezing step determines the pore size distribution within the product, which, in turn, affects the sublimation rate. Traditionally, pore analysis is carried out on SEM images by means of a manual, time-consuming approach. Here, an image segmentation technique was used to automatize this process and improve its reliability. A 3D structure of the cake was then reconstructed from the distribution of the super-pixels. We show that the approach herein proposed can remarkably improve prediction of the sublimation rate with respect to traditional methods. Keywords: Freezing; Freeze-Drying; Image Segmentation; 3D Reconstruction

scholarly journals Experimental investigation on pore size distribution and drying kinetics during lyophilization of sugar solutions

2018 ◽  
Author(s):  
Petra Foerst ◽  
M. Lechner ◽  
N. Vorhauer ◽  
H. Schuchmann ◽  
E. Tsotsas
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Freeze Drying ◽  
Three Dimensional ◽  
Drying Kinetics ◽  
Process Efficiency ◽  
Freeze Dried ◽  
Pore Size Distributions

The pore structure is a decisive factor for the process efficiency and product quality of freeze dried products. In this work the two-dimensional ice crystal structure was investigated for maltodextrin solutions with different concentrations by a freeze drying microscope. The resulting drying kinetics was investigated for different pore structures. Additionally the three-dimensional pore structure of the freeze dried samples was measured by µ-computed tomography and the pore size distribution was quantified by image analysis techniques. The two- and three-dimensional pore size distributions were compared and linked to the drying kinetics.Keywords: pore size distribution; freeze drying; maltodextrin solution; freeze drying microscope   

scholarly journals Fabrication of PES/PVP Water Filtration Membranes Using Cyrene®, a Safer Bio-Based Polar Aprotic Solvent

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Roxana A. Milescu ◽  
C. Robert McElroy ◽  
Thomas J. Farmer ◽  
Paul M. Williams ◽  
Matthew J. Walters ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Water Filtration ◽  
Solubility Parameters ◽  
Coagulation Bath ◽  
Additive Concentration ◽  
Sem Images ◽  
Water Contact ◽  
Water Permeation

A more sustainable dialysis and water filtration membrane has been developed, by using the new, safer, bio-based solvent Cyrene® in place of N-methyl pyrrolidinone (NMP). The effects of solvent choice, solvent evaporation time, the temperature of casting gel, and coagulation bath together with the additive concentration on porosity and pore size distribution were studied. The results, combined with infrared spectra, SEM images, porosity results, water contact angle (WCA), and water permeation, confirm that Cyrene® is better media to produce polyethersulfone (PES) membranes. New methods, Mercury Intrusion Porosimetry (MIP) and NMR-based pore structure model, were applied to estimate the porosity and pore size distribution of the new membranes produced for the first time with Cyrene® and PVP as additive. Hansen Solubility Parameters in Practice (HSPiP) was used to predict polymer-solvent interactions. The use of Cyrene® resulted in reduced polyvinylpyrrolidone (PVP) loading than required when using NMP and gave materials with larger pores and overall porosity. Two different conditions of casting gel were applied in this study: a hot (70°C) and cold gel (17°C) were cast to obtain membranes with different morphologies and water filtration behaviours.

scholarly journals Revealing the True Morphological Structure of Macroporous Soft Hydrogels for Tissue Engineering

2020 ◽  
Vol 10 (19) ◽  
pp. 6672
Author(s):  
Bohumila Podhorská ◽  
Miroslav Vetrík ◽  
Eva Chylíková-Krumbholcová ◽  
Lucie Kománková ◽  
Niloufar Rashedi Banafshehvaragh ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Pore Size ◽  
Laser Scanning ◽  
Morphological Changes ◽  
3D Structure ◽  
Morphological Structure ◽  
Laser Scanning Confocal Microscopy ◽  
Future Application ◽  
Sem Images ◽  
Hydrogel Scaffolds

(1) Background: Macroporous hydrogel scaffolds based on poly [N-(2-hydroxypropyl) methacrylamide] are one of the widely studied biocompatible materials for tissue reparation and regeneration. This study investigated the morphological changes during hydrogel characterization which can significantly influence their future application. (2) Methods: Three types of macroporous soft hydrogels differing in pore size were prepared. The macroporosity was achieved by the addition of sacrificial template particles of sodium chloride of various sizes (0–30, 30–50, and 50–90 µm) to the polymerizing mixture. The 3D structure of the hydrogels was then investigated by scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM). The SEM was performed with specimens rapidly frozen to various temperatures, while non-frozen gels were visualized with LSCM. (3 and 4) Results and Conclusion: In comparison to LSCM, the SEM images revealed a significant alteration in the mean pore size and appearance of newly formed multiple connections between the pores, depending on the freezing conditions. Additionally, after freezing for SEM, the gel matrix between the pores and the fine pores collapsed. LSCM visualization aided the understanding of the dynamics of pore generation using sodium chloride, providing the direct observation of hydrogel scaffolds with the growing cells. Moreover, the reconstructed confocal z-stacks were a promising tool to quantify the swollen hydrogel volume reconstruction which is not possible with SEM.

scholarly journals Pore Network Analysis of Zone Model for Porous Media Drying

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yuan Yuejin ◽  
Zhao Zhe ◽  
Nie Junnan ◽  
Xu Yingying
Keyword(s):  
Porous Media ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Phase Distribution ◽  
Pore Network ◽  
Pore Network Model ◽  
Zone Model ◽  
Drying Process ◽  
Isothermal Drying

In view of the fact that the zone model for porous media drying cannot disclose the mechanism of liquid phase distribution effectively, a pore network model for the slow isothermal drying process of porous media was developed by applying the theories of pore network drying and transport-process, which fused the physical parameters of porous media, such as porosity, pore mean diameter, and pore size distribution into the model parameters, and a sand bed drying experiment was conducted to verify the validity of this model. The experiment and simulation results indicate that the pore network model could explain the slow isothermal drying process of porous media well. The pore size distributions of porous media have a great effect on the liquid phase distribution of the drying process. The dual-zone model is suitable for the porous media whose pore size distribution obeys Gaussian distribution, while the three-zone model is suitable for the porous media whose pore size distribution obeys the lognormal distribution when the drying analysis of porous media is conducted.

scholarly journals Freeze-drying and its application to some Finnish agricultural products

1985 ◽  
Vol 57 (2) ◽  
pp. 125-131 ◽  
Author(s):  
Yrjö Roos ◽  
Jorma J. Laine
Keyword(s):  
Moisture Content ◽  
Freeze Drying ◽  
Nitrogen Atmosphere ◽  
Agricultural Products ◽  
Drying Process ◽  
Sublimation Rate ◽  
Freeze Dried ◽  
Being There ◽  
Drying Chamber ◽  
Maximum Surface Temperature

This study deals with the freeze-drying of berries, vegetables, roots and pork produced in Finland. The products were freeze dried whole, in slices or cubes. The pressure in the drying chamber was 10—20 Pa and the maximum surface temperature +23—+ 40°C. The products were packed after freeze-drying into glass jars under air and in polyester-aluminium-polyethene foil under vacuum or nitrogen atmosphere. The drying temperatures and drying times were measured. During storage for 4 months, the differences in quality were evaluated. The drying times ranged from 8 to 25 hours. The moisture content of the dry products was 1—3 %. The sublimation rate at the beginning of the drying process was very rapid, being there after constant. Bilberries, carrots and radishes collapsed during drying. Most of the products dried moistened and underwent aroma changes during storage in glass jars under air. The products packed under vacuum or nitrogen atmosphere proved stable.

scholarly journals Fractal Properties of Various Clay Minerals Obtained from SEM Images

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Naser Golsanami ◽  
Shanilka Gimhan Fernando ◽  
Madusanka Nirosh Jayasuriya ◽  
Weichao Yan ◽  
Huaimin Dong ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Clay Minerals ◽  
Pore Space ◽  
Reservoir Rock ◽  
Distribution Area ◽  
Sem Images ◽  
Fractal Properties ◽  
Internal Pore

Clay minerals significantly alter the pore size distribution (PSD) of the gas hydrate-bearing sediments and sandstone reservoir rock by adding an intense amount of micropores to the existing intragranular pore space. Therefore, in the present study, the internal pore space of various clay groups is investigated by manually segmenting Scanning Electron Microscopy (SEM) images. We focused on kaolinite, smectite, chlorite, and dissolution holes and characterized their specific pore space using fractal geometry theory and parameters such as pore count, pore size distribution, area, perimeter, circularity, and density. Herein, the fractal properties of different clay groups and dissolution holes were extracted using the box counting technique and were introduced for each group. It was observed that the presence of clays complicates the original PSD of the reservoir by adding about 1.31-61.30 pores/100 μm2 with sizes in the range of 0.003-87.69 μm2. Meanwhile, dissolution holes complicate the pore space by adding 4.88-8.17 extra pores/100 μm2 with sizes in the range of 0.06-119.75 μm2. The fractal dimension ( D ) and lacunarity ( L ) values of the clays’ internal pore structure fell in the ranges of 1.51-1.85 and 0.18-0.99, respectively. Likewise, D and L of the dissolution holes were in the ranges of, respectively, 1.63-1.65 and 0.56-0.62. The obtained results of the present study lay the foundation for developing improved fractal models of the reservoir properties which would help to better understand the fluid flow, irreducible fluid saturation, and capillary pressure. These issues are of significant importance for reservoir quality and calculating the accurate amount of producible oil and gas.

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