Practice for Preservation by Freezing, Freeze-Drying, and Low Temperature Maintenance of Bacteria, Fungi, Protista, Viruses, Genetic Elements, and Animal and Plant Tissues

10.1520/e1342 ◽  
2011 ◽  
Author(s):  
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Plant Tissues ◽  
Genetic Elements ◽  
Preservation By Freezing

scholarly journals Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1738
Author(s):  
Saeid Vafaei ◽  
Alexander Wolosz ◽  
Catlin Ethridge ◽  
Udo Schnupf ◽  
Nagisa Hattori ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Freeze Drying ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Functional Materials ◽  
Cost Effective ◽  
High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

Freeze-Drying of Plant Tissues

Nature ◽  
1962 ◽  
Vol 195 (4845) ◽  
pp. 1014-1016
Author(s):  
R. THAINE
Keyword(s):  
Freeze Drying ◽  
Plant Tissues

scholarly journals Effect of Thermal Processing on Antioxidant Activity and Cytotoxicity of Waste Potato Juice

2019 ◽  
Vol 14 (1) ◽  
pp. 150-157 ◽  
Author(s):  
Przemysław Łukasz Kowalczewski ◽  
Anna Olejnik ◽  
Wojciech Białas ◽  
Piotr Kubiak ◽  
Aleksander Siger ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Low Temperature ◽  
Cytotoxic Activity ◽  
Spray Drying ◽  
Cell Lines ◽  
Freeze Drying ◽  
Cytotoxic Activities ◽  
Normal Cells ◽  
Stabilization Methods ◽  
The Impact

AbstractPotato juice (PJ), commonly considered a burdensome waste, is rich in various compounds with bioactive properties. It has long been considered a remedy for gastric problems in traditional folk medicine. If valorization of PJ through implementation in the production of functional foods is to be considered, stabilization methods must be developed to allow long-term storage of this seasonal product. It is important that such methods are chosen with regard to their effect on the bioactive value of the obtained product. In this study, the impact of four stabilization methods on the antioxidant and cytotoxic activities of PJ was investigated. Elevated temperatures were used in thermal deproteinization used to obtain DPJW (deproteinated potato juice water) and spray-drying of FPJ (fresh potato juice) that resulted in SDPJ. Freeze drying and cryoconcentration were the low temperature processing methods that yielded PJL (potato juice lyophilisate) and CPJ (cryocorncentrated potato juice), respectively. All processed materials were characterized chemically and compared with raw materials in terms of phenolic compounds content, antioxidant activity as well as cytotoxicity to human tumor cells isolated from the gastric mucosa (Hs476T cell line), colon (Caco-2 and HT-29 cell lines), and normal cells isolated from the small intestine and colon epithelium (IEC-6 and NCM460 cell lines). It was stated that high-temperature processes – thermal deproteinization and spray-drying – yielded products with increased antioxidant potential (TEAC) that also showed increased cytotoxic activity towards intestinal cancer cells. At the same time the cytotoxicity towards normal cells remained on par with that of fresh PJ (IEC-6 cells) or decreased (NCM460 cells). Thermal deproteinization significantly decreased the content of glycoalcaloids in the juice, while spray drying did not have such an effect. The two low-temperature processes investigated – cryoconcentration and freeze drying – did not affect the PJ cytotoxic activity towards any of the cell lines used in the tests, whereas they did affect the antioxidant properties and glycoalcaloids content of PJ.

scholarly journals Analysis of Heat Transfer Mechanism for Shelf Vacuum Freeze-Drying Equipment

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hong-Ping Cheng ◽  
Shian-Min Tsai ◽  
Chin-Chi Cheng
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Freeze Drying ◽  
Heat Transfer Fluid ◽  
Processing Temperature ◽  
Fluid Temperature ◽  
Three Dimension ◽  
Flow Rates

Vacuum freeze-drying technology is applicable to the process of high heat-sensitive products. Due to the long drying period and extremely low processing temperature and pressure, the uniform and efficiency of heat transfer fluid temperature in shelf are critical for product quality. Therefore, in this study, the commercial computer fluid dynamics (CFD) software, FLUENT, was utilized for three-dimension numerical simulation of the shelf vacuum freeze-drying process. The influences of different inlet and outlet positions for shelves on the uniformity of the flow rate and temperature were discussed. Moreover, it explored the impacts on the temperature gradient of shelves after heat exchange of different flow rates and low temperature materials. In order to reduce the developing time and optimize the design, the various secondary refrigerants in different plies of shelves were investigated. According to the effect of heat exchange between different flow rates and low temperature layer material shelves on the temperature gradient of shelves surface, the minimum temperature gradient was 20 L/min, and the maximum was 2.5 L/min.

Simulations and Measurements of Water Vapor Flow and Ice Dynamics in a Freeze-Dryer Condenser

2011 ◽  
Author(s):  
Arnab Ganguly ◽  
Alina Alexeenko ◽  
Frank DeMarco
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Mass Flux ◽  
Freeze Drying ◽  
Laboratory Scale ◽  
Vapor Flow ◽  
Ice Accretion ◽  
Production Scale ◽  
Ice Dynamics ◽  
Freeze Dryer

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of pharmaceuticals for removal of solvents by sublimation. The performance of a freeze-dryer condenser is largely dependent on the vapor and ice dynamics in the low-pressure environment. The main objective of this work is to develop a modeling and computational framework for analysis of vapor flow and ice dynamics in such freeze-dryer condensers. The direct Simulation Monte Carlo (DSMC) technique is applied to model the relevant physical processes that accompany the vapor flow in the condenser chamber. Low-temperature water vapor and nitrogen molecular model is applied in the DSMC solver SMILE to simulate the bulk vapor transport. The developing ice front on the coils of the condenser is tracked based on the steady state mass flux computed at the nodes of the DSMC surface mesh. Verification of ice accretion simulations has been done by comparison with the solution for analytical free-molecular flow over a circular cylinder. The developed model has also been validated with measurements of ice growth in a laboratory and production scale freeze-dryer using time-lapse imaging. To illustrate the application of the ice accretion algorithm in the area of bio-pharmaceutical freeze-drying, the current work discusses the effect of the condenser geometry and non-condensable gas on non-uniformity of mass flux in a laboratory scale and production scale freeze-dryer condenser. In addition, the simulations are used to predict the ice formation on the coils of the condenser. It was found that in the laboratory scale dryer, the presence of a duct connecting the product chamber and condenser increased non-uniformity by 65% at a sublimation rate of 5 g/hr. The measured ice thickness on the coils of the condenser was found to increase non-linearly. This non-linearity was captured within an accuracy of 1% compared to the measurements towards the end of a 24 hour cycle using an unsteady icing model while that using a steady model was within 14%. In the production dryer, while the steady model predicted the iced coil diameter within an accuracy of 2–5% with respect to the measurements, the unsteady model captured this within an accuracy of 1–6%. The DSMC simulations demonstrate that by augmenting its capabilities with the icing model, it is possible to predict the performance of a freeze-dryer condenser with any arbitrary design.

Effect of Ethylene on the Respiratory Response of Isolated Sweet Potato Mitochondria

1978 ◽  
Vol 5 (3) ◽  
pp. 239 ◽  
Author(s):  
GP Arron ◽  
DA Day ◽  
SD Grover ◽  
GG Laties
Keyword(s):  
Low Temperature ◽  
Sweet Potato ◽  
Redox State ◽  
Plant Hormone ◽  
Plant Tissues ◽  
Respiratory Response ◽  
Apparent Effect ◽  
Uptake Rates ◽  
Stimulation Of

The plant hormone ethylene had no apparent effect on the redox state of the respiratory chain components of sweet potato mitochondria during oxidation of succinate. Low temperature e.p.r. spectra of sweet potato mitochondria, in various respiratory states, were not altered by the presence of ethylene. Oxygen uptake rates and ADP/O ratios of sweet potato mitochondria oxidising malate or succinate were also not affected by ethylene. The role of ethylene in the stimulation of respiration in plant tissues is discussed.

Sign in / Sign up

Export Citation Format

Share Document