scholarly journals Separation of Contaminants in The Freeze/Thaw Process

2017 ◽  
Vol 38 (2) ◽  
pp. 249-264 ◽  
Author(s):  
Janusz A. Szpaczyński ◽  
Jeffrey A. White ◽  
Caroline L. Côté
Keyword(s):  
High Efficiency ◽  
Solid Particles ◽  
Liquid Volume ◽  
Freezing And Thawing ◽  
Repeated Freezing ◽  
Clay Slurry ◽  
Thawing Processes ◽  
High Degree ◽  
Degree Of Purification ◽  
Significant Concentration

AbstractThese studies examined the concept of concentration and purification of several types of wastewater by freezing and thawing. The experiments demonstrated that freezing of contaminated liquid contributed to concentration of contaminants in solution as well as significant concentration and agglomeration of solid particles. A high degree of purification was achieved for many parameters. The results of comparative laboratory tests for single and multiple freezing are presented. It was found that there was a higher degree of concentration of pollutants in wastewater frozen as man-made snow than in bulk ice. Furthermore, the hypothesis that long storage time of liquid as snow and sufficient temperature gradient metamorphism allows for high efficiency of the concentration process was confirmed. It was reported that the first 30% of the melted liquid volume contained over 90% of all impurities. It gives great opportunities to use this method to concentrate pollutants. The results revealed that the application of this process in full scale is possible. Significant agglomeration of solid particles was also noted. Tests with clay slurry showed that repeated freezing and thawing processes significantly improve the characteristics of slurry for sedimentation and filtration.

scholarly journals FREEZING AND THAWING | Processes

2005 ◽  
pp. 104-110 ◽  
Author(s):  
G.N. Flerchinger ◽  
G.A. Lehrsch ◽  
D.K. McCool
Keyword(s):  
Freezing And Thawing ◽  
Thawing Processes

scholarly journals ISOZYMES OF ACID PHOSPHATASE IN NORMAL AND CALMETTE-GUÉRIN BACILLUS-INDUCED RABBIT ALVEOLAR MACROPHAGES

1968 ◽  
Vol 128 (5) ◽  
pp. 1031-1048 ◽  
Author(s):  
S. G. Axline
Keyword(s):  
Acid Phosphatase ◽  
Phosphatase Activity ◽  
Alveolar Macrophages ◽  
Acid Phosphatase Activity ◽  
Enzyme Inhibitors ◽  
Freezing And Thawing ◽  
Ph Optimum ◽  
Lysosomal Fraction ◽  
Repeated Freezing ◽  
Major Acid

The acid phosphatase activity of normal alveolar and BCG-induced alveolar macrophages has been examined. Five electrophoretically distinct forms of acid phosphatase have been identified in both normal and BCG-induced macrophages. The acid phosphatases can be divided into two major categories. One category, containing four distinct forms, is readily solubilized after repeated freezing and thawing or mechanical disruption The second category, containing one form, is firmly bound to the lysosomal membrane and can be solubilized by treatment of the lysosomal fraction with Triton X-100. The Triton-extractable acid phosphatase and the predominant aqueous soluble acid phosphatase have been shown to differ in the degree of membrane binding, in solubility, in net charge, and in molecular weight. The two pre-dominant phosphatases possess identical pH optimum and do not differ in response to enzyme inhibitors. BCG stimulation has been shown to result in a nearly twofold increase in acid phosphatase activity. A nearly proportionate increase in the major acid phosphatase forms has been observed.

scholarly journals Cryopreservation: The secret of modern preservation of brewer’s yeasts – minireview

2021 ◽  
Vol 67 (1) ◽  
pp. 403-408
Author(s):  
Katarína Hanzalíková ◽  
Petra Kubizniakova ◽  
Lucie Kyselová ◽  
Dagmar Matoulková
Keyword(s):  
Cell Damage ◽  
Cellular Structures ◽  
Biological Functions ◽  
Freezing And Thawing ◽  
Thawing Processes ◽  
Thawing Rate ◽  
Brewer’S Yeasts ◽  
Long Term Preservation ◽  
Stress Accumulation

The aim of the long-term preservation of cells, tissues and organs is to maintain their cellular structures and biological functions for as long as possible. Cryopreservation is a process where biological material is stored and preserved at very low temperatures. However, freezing and thawing processes can cause irreversible cell damage, which is related to formation of ice crystals, osmotic stress, accumulation of reactive forms of oxygen, etc. Therefore the cell viability depends mainly on the freezing rate, the composition of the cryoprotective medium as well as on the thawing rate. Using a suitable cryoprotective medium can increase the viability rate of the yeasts after “revitalization“. Appropriate pre-cultivation before freezing also plays an important role. These facts show that cell freezing and thawing processes must be controlled to avoid cell damage.

scholarly journals Autonomous Reaction Network Exploration in Homogeneous and Heterogeneous Catalysis

2022 ◽  
Author(s):  
Miguel Steiner ◽  
Markus Reiher
Keyword(s):  
High Efficiency ◽  
Reaction Network ◽  
Decomposition Reactions ◽  
Full Resolution ◽  
Manual Inspection ◽  
Computational Procedures ◽  
Fast Electronic ◽  
Processing Errors ◽  
High Degree ◽  
Computational Catalysis

AbstractAutonomous computations that rely on automated reaction network elucidation algorithms may pave the way to make computational catalysis on a par with experimental research in the field. Several advantages of this approach are key to catalysis: (i) automation allows one to consider orders of magnitude more structures in a systematic and open-ended fashion than what would be accessible by manual inspection. Eventually, full resolution in terms of structural varieties and conformations as well as with respect to the type and number of potentially important elementary reaction steps (including decomposition reactions that determine turnover numbers) may be achieved. (ii) Fast electronic structure methods with uncertainty quantification warrant high efficiency and reliability in order to not only deliver results quickly, but also to allow for predictive work. (iii) A high degree of autonomy reduces the amount of manual human work, processing errors, and human bias. Although being inherently unbiased, it is still steerable with respect to specific regions of an emerging network and with respect to the addition of new reactant species. This allows for a high fidelity of the formalization of some catalytic process and for surprising in silico discoveries. In this work, we first review the state of the art in computational catalysis to embed autonomous explorations into the general field from which it draws its ingredients. We then elaborate on the specific conceptual issues that arise in the context of autonomous computational procedures, some of which we discuss at an example catalytic system. Graphical Abstract

scholarly journals STUDIES ON OXIDATION AND REDUCTION BY PNEUMOCOCCUS

1924 ◽  
Vol 39 (3) ◽  
pp. 357-366 ◽  
Author(s):  
Oswald T. Avery ◽  
James M. Neill
Keyword(s):  
Yeast Extract ◽  
Room Temperature ◽  
Prolonged Exposure ◽  
Freezing And Thawing ◽  
Peroxide Formation ◽  
Cell Extracts ◽  
Repeated Freezing ◽  
Phosphate Solutions ◽  
Animal Tests

In the present paper methods have been described for the preparation of sterile extracts of pneumococci. These extracts may be obtained by dissolving the bacteria in broth cultures by means of bile, or by extraction of the cellular substances by repeated freezing and thawing of broth or saline suspensions of unwashed cells. Under special precautions these extracts may be passed through Berkefeld filters without loss of potency. In this procedure, as in all other manipulations incident to their preparation, the extracts should be protected as far as possible from contact with air. All extracts were proved sterile by cultural and animal tests. Sterile extracts of unwashed pneumococcus cells promptly form peroxide on exposure to air. Peroxide formation is almost as active in extracts aerated at 2°C. as in those exposed to the air at room temperature. Detectable amounts of peroxide may be produced by these cell extracts within the reaction range of pH 5 to 9, the optimal zone lying at reactions less acid than pH 6. The peroxide-forming activity of the extracts is gradually diminished by prolonged exposure to 55°C., and is completely destroyed by heating at 65°C. for 5 minutes. Cell extracts of pneumococci which have been thoroughly washed prior to extraction in salt or phosphate solutions exhibit no peroxide-forming activity. These extracts of washed cells may be activated by the addition of the cell washings, yeast extract, or muscle infusion.

Effects of perturbations and stimulants on red raspberry (Rubus idaeus L.) seed germination

1997 ◽  
Vol 73 (4) ◽  
pp. 453-457 ◽  
Author(s):  
R. A. Lautenschlager
Keyword(s):  
Seed Coat ◽  
Temperature Fluctuations ◽  
Rubus Idaeus ◽  
Red Raspberry ◽  
Freezing And Thawing ◽  
Short Term ◽  
Repeated Freezing ◽  
Key Words Animal ◽  
Concentrated Sulfuric Acid ◽  
Seed Coats

Red raspberry (Rubus idaeus L.) seeds germinate only after seed coats are degraded. In nature this happens slowly. Seeds from recently collected fruit (fresh to four years old) germinated only after scarification of the seed coat by 20-minute soaking in concentrated sulfuric acid. Germination was not enhanced by: (1) short-term intermittent soaking, up to 81 hours, in dilute (0.01 normal) hydrochloric acid; (2) passage through the digestive tracts of bears, coyotes, or birds; (3) physical perturbations such as nicking, mechanical scarification, repeated freezing and thawing and/or four years of exposure in the field; (4) exposure to light; (5) increased temperatures or temperature fluctuations; or (6) addition of nitrogen (ammonium nitrate, urea). Key words: animal passage, germination, nitrogen, red raspberry, Rubus idaeus L., seed coat, seed weight, scarification, stratification

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