scholarly journals Alterations in Chloroplast Thylakoids during an in Vitro Freeze-Thaw Cycle

1976 ◽  
Vol 57 (5) ◽  
pp. 673-680 ◽  
Author(s):  
Melvin P. Garber ◽  
Peter L. Steponkus
Keyword(s):  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Dynamics of Texture Change and in Vitro Starch Digestibility with High-Pressure, Freeze-Thaw Cycle, and Germination-Parboiling Treatments of Brown Rice

2021 ◽  
Vol 64 (1) ◽  
pp. 103-115
Author(s):  
Hao Wang ◽  
Songming Zhu ◽  
Hosahalli S. Ramaswamy ◽  
Yang Du ◽  
Yong Yu ◽  
...  
Keyword(s):  
High Pressure ◽  
Glycemic Index ◽  
Amylose Content ◽  
Brown Rice ◽  
In Vitro Digestibility ◽  
White Rice ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

HighlightsFreeze-thaw cycle (FTC) treated brown rice texture was much closer to white rice texture.Both high-pressure (HP) and FTC treatment helped to moderate the bran layer of brown rice.FTC treatment of brown rice resulted in higher conversion to resistant starch.The glycemic index of treated rice correlated positively with the amylose/amylopectin ratio.Abstract. High-pressure (HP), freeze-thaw cycle (FTC), and germination-parboiling (GP) treatments were used to improve the texture characteristics and in vitro digestibility of starch in brown rice (BR). The texture of FTC-treated BR was the closest to the texture of white rice. Improved water absorption ratio, HP and FTC induced modification of the bran layer, and GP induced partial starch gelatinization were considered to be responsible for improving the texture of BR. All treatments improved the in vitro digestibility of BR starch, and FTC < HP < GP with respect to the order of increase. FTC treatment also resulted in the minimal glycemic index (GI), while GP treatment resulted in higher GI. In general, the amylose content was lower for untreated BR than for treated BR. Further, the HP, GP, and FTC treatments showed improved amylose/amylopectin ratios. HP and GP decreased the gelatinization enthalpy, while FTC increased it. GI had a positive correlation with amylose content and amylose/amylopectin ratio, while gelatinization enthalpy had a negative correlation. Keywords: Brown rice, Freeze-thaw cycle, Germination-parboiling, High pressure, Starch in vitro digestibility, Texture.

Comparison of Germination-Parboiling, Freeze-Thaw Cycle and High Pressure Processing on Phytochemical Content and Antioxidant Activity in Brown Rice Evaluated after Cooking and In-Vitro Digestion

2018 ◽  
Vol 14 (11-12) ◽  
Author(s):  
Yong Yu ◽  
Yang Du ◽  
Hosahalli S. Ramaswamy ◽  
Hao Wang ◽  
Xiuping Jiang ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
High Pressure ◽  
Brown Rice ◽  
In Vitro Digestion ◽  
High Pressure Processing ◽  
Phytochemical Content ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Abstract Three treatments, namely germination-parboiling (PG), freeze-thaw cycle (FTC) and high pressure processing (HPP) were compared for phytochemical content and antioxidant activity of brown rice (BR). These were determined in raw (uncooked), cooked, and in-vitro digested BR and compared with those from untreated BR and white rice (WR). PG showed the highest retention of phytochemicals after cooking (87–100%) while it dropped to 59–72% with FTC and 64–76% with HPP. After in-vitro digestion, the highest amount of phenolics was found in PG-24 h and flavonoids in FTC for two cycles. The antioxidant activity, as determined by oxygen radical absorbance capacity and ABTS methods, showed the highest value to be associated with in-vitro digested sample of PG-24 h, and lowest in WR. The results of this study show that these three treatments could improve or retain the phenolic content and antioxidant activity in cooked BR after in-vitro digestion.

Effects of Refrigeration and Freezing on the Electromechanical and Biomechanical Properties of Articular Cartilage

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Adele Changoor ◽  
Liah Fereydoonzad ◽  
Alex Yaroshinsky ◽  
Michael D. Buschmann
Keyword(s):  
Articular Cartilage ◽  
Experimental Testing ◽  
Biomechanical Testing ◽  
Biomechanical Properties ◽  
Fresh Tissue ◽  
Testing Procedures ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

In vitro electromechanical and biomechanical testing of articular cartilage provide critical information about the structure and function of this tissue. Difficulties obtaining fresh tissue and lengthy experimental testing procedures often necessitate a storage protocol, which may adversely affect the functional properties of cartilage. The effects of storage at either 4°C for periods of 6 days and 12 days, or during a single freeze-thaw cycle at −20°C were examined in young bovine cartilage. Non-destructive electromechanical measurements and unconfined compression testing on 3 mm diameter disks were used to assess cartilage properties, including the streaming potential integral (SPI), fibril modulus (Ef), matrix modulus (Em), and permeability (k). Cartilage disks were also examined histologically. Compared with controls, significant decreases in SPI (to 32.3±5.5% of control values, p<0.001), Ef (to 3.1±41.3% of control values, p=0.046), Em (to 6.4±8.5% of control values, p<0.0001), and an increase in k (to 2676.7±2562.0% of control values, p=0.004) were observed at day 12 of refrigeration at 4°C, but no significant changes were detected at day 6. A trend toward detecting a decrease in SPI (to 94.2±6.2% of control values, p=0.083) was identified following a single freeze-thaw cycle, but no detectable changes were observed for any biomechanical parameters. All numbers are mean±95% confidence interval. These results indicate that fresh cartilage can be stored in a humid chamber at 4°C for a maximum of 6 days with no detrimental effects to cartilage electromechanical and biomechanical properties, while one freeze-thaw cycle produces minimal deterioration of biomechanical and electromechanical properties. A comparison to literature suggested that particular attention should be paid to the manner in which specimens are thawed after freezing, specifically by minimizing thawing time at higher temperatures.

scholarly journals Breast Cancer Cryoablation: Assessment of the Impact of Fundamental Procedural Variables in an In Vitro Human Breast Cancer Model

2020 ◽  
Vol 14 ◽  
pp. 117822342097236
Author(s):  
Kristi K Snyder ◽  
Robert G Van Buskirk ◽  
John G Baust ◽  
John M Baust
Keyword(s):  
Breast Cancer ◽  
Cell Death ◽  
Human Breast Cancer ◽  
Human Breast ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Impact ◽  
Mcf 7

Introduction: Breast cancer is the most prominent form of cancer and the second leading cause of death in women behind lung cancer. The primary modes of treatment today include surgical excision (lumpectomy, mastectomy), radiation, chemoablation, anti-HER2/neu therapy, and/or hormone therapy. The severe side effects associated with these therapies suggest a minimally invasive therapy with fewer quality of life issues would be advantageous for treatment of this pervasive disease. Cryoablation has been used in the treatment of other cancers, including prostate, skin, and cervical, for decades and has been shown to be a successful minimally invasive therapeutic option. To this end, the use of cryotherapy for the treatment of breast cancer has increased over the last several years. Although successful, one of the challenges in cryoablation is management of cancer destruction in the periphery of the ice ball as the tissue within this outer margin may not experience ablative temperatures. In breast cancer, this is of concern due to the lobular nature of the tumors. As such, in this study, we investigated the level of cell death at various temperatures associated with the margin of a cryogenic lesion as well as the impact of repetitive freezing and thawing methods on overall efficacy. Methods: Human breast cancer cells, MCF-7, were exposed to temperatures of −5°C, −10°C, −15°C, −20°C, or −25°C for 5-minute freeze intervals in a single or repeat freeze-thaw cycle. Samples were thawed with either passive or active warming for 5 or 10 minutes. Samples were assessed at 1, 2, and 3 days post-freeze to assess cell survival and recovery. In addition, the modes of cell death associated with freezing were assessed over the initial 24-hour post-thaw recovery period. Results: Exposure of MCF-7 cells to −5°C and −10°C resulted in minimal cell death regardless of the freeze/thaw conditions. Freezing to a temperature of −25°C resulted in complete cell death 1 day post-thaw with no cell recovery in all freeze/thaw scenarios evaluated. Exposure to a single freeze event resulted in a gradual increase in cell death at −15°C and −20°C. Application of a repeat freeze-thaw cycle (dual 5-minute freeze) resulted in an increase in cell death with complete destruction at −20°C and near complete death at −15°C (day 1 survival: single −15°C freeze/thaw = 20%; repeated −15°C freeze/thaw = 4%). Analysis of thaw interval time (5 vs 10 minute) demonstrated that the shorter 5-minute thaw interval between freezes resulted in increased cell destruction. Furthermore, investigation of thaw rate (active vs passive thawing) demonstrated that active thawing resulted in increased cell survival thereby less effective ablation compared with passive thawing (eg, −15°C 5/10/5 procedure survival, passive thaw: 4% vs active thaw: 29%). Conclusions: In summary, these in vitro findings suggest that freezing to temperatures of 25°C results in a high degree of breast cancer cell destruction. Furthermore, the data demonstrate that the application of a repeat freeze procedure with a passive 5-minute or 10-minute thaw interval between freeze cycles increases the minimal lethal temperature to the −15°C to −20°C range. The data also demonstrate that the use of an active thawing procedure between freezes reduces ablation efficacy at temperatures associated with the iceball periphery. These findings may be important to improving future clinical applications of cryoablation for the treatment of breast cancer.

scholarly journals Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Longxiao Chen ◽  
Kesheng Li ◽  
Guilei Song ◽  
Deng Zhang ◽  
Chuanxiao Liu
Keyword(s):  
Mechanical Properties ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Physical And Mechanical Properties ◽  
Freeze Thaw ◽  
Damage Characteristics ◽  
Large Pore ◽  
Natural Rock ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

Non-linear creep damage model of sandstone under freeze-thaw cycle

2021 ◽  
Vol 28 (3) ◽  
pp. 954-967
Author(s):  
Jie-lin Li ◽  
Long-yin Zhu ◽  
Ke-ping Zhou ◽  
Hui Chen ◽  
Le Gao ◽  
...  
Keyword(s):  
Damage Model ◽  
Creep Damage ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Linear Creep ◽  
Non Linear ◽  
Freeze Thaw Cycle ◽  
Creep Damage Model
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