Vitrification Solutions for the Cryopreservation of Tissue-Engineered Bone

2002 ◽  
Author(s):  
B. L. Liu ◽  
J. J. McGrath
Keyword(s):  
Bending Strength ◽  
Cell Damage ◽  
Mechanical Damage ◽  
Bone Substitutes ◽  
State University ◽  
Scanning Calorimetry ◽  
Destructive Effect ◽  
Cryoprotective Agents ◽  
Liquid Suspension ◽  
High Concentrations

Osteoblast (OB)-seeded hydroxyapatite (HA) scaffold cortical bone substitutes are being developed at Michigan State University. Preservation methods need to be developed to preserve such living products to ensure a steady supply for transplantation. Theoretically vitrification is an attractive method for the cryopreservation of tissue-engineered bone because it can eliminate the destructive effect of ice formation [1]. However, relatively fast cooling and warming rates are required to avoid damage associated with ice crystallization and relatively high concentrations of cryoprotective agents (CPAs) are required to achieve a glassy (vitrified) state. These rapid rates of temperature change may not be possible as tissue-engineered structures become larger. In addition to cell damage, rapid rates may also cause destructive thermo mechanical damage to the scaffold itself. Slower rates can be used to achieve the vitrified state but this requires higher CPA concentrations, which are more toxic. As a means of studying the interactive determinants of an optimal vitrification process for osteoblasts, we have undertaken thermal analysis of a variety of vitrification solutions of interest using differential scanning calorimetry (DSC) to determine the critical cooling and warming rates. The toxicity dynamics and tendency for the scaffolds to be damaged mechanically by the vitrification process are also examined. Glycerol and dimethyl sulfoxide at a concentration of 40% were studied with and without an ice blocker. Two vitrification “cocktails” (VS55 and VEG) over a concentration range of 80% to 100% were studied with and without an ice blocker. On the basis of these studies 95% VEG with ice blocker was least toxic and yielded the highest recovery (∼90%) for OBs vitrified in liquid suspension. Vitrification does not seem to be detrimental to the bending strength of high density (low porosity) HA scaffolds, but lower density HA scaffolds break more easily after vitrification in some instances.

scholarly journals Utilization of Birch Bark as an Eco-Friendly Filler in Urea-Formaldehyde Adhesives for Plywood Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 511
Author(s):  
Roman Réh ◽  
Ľuboš Krišťák ◽  
Ján Sedliačik ◽  
Pavlo Bekhta ◽  
Monika Božiková ◽  
...  
Keyword(s):  
Bending Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Birch Bark ◽  
Gravimetric Analysis ◽  
European Standard ◽  
Scanning Calorimetry ◽  
Wood Processing ◽  
Fagus Sylvatica L ◽  
Positive Effect

The potential of using ground birch (Betula verrucosa Ehrh.) bark as an eco-friendly additive in urea-formaldehyde (UF) adhesives for plywood manufacturing was investigated in this work. Five-ply plywood panels were fabricated in the laboratory from beech (Fagus sylvatica L.) veneers bonded with UF adhesive formulations comprising three addition levels of birch bark (BB) as a filler (10%, 15%, and 20%). Two UF resin formulations filled with 10% and 20% wheat flour (WF) were used as reference samples. The mechanical properties (bending strength, modulus of elasticity and shear strength) of the laboratory-fabricated plywood panels, bonded with the addition of BB in the adhesive mixture, were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical strength of the plywood with the addition of BB in the adhesive mixture is acceptable and met the European standard requirements. Markedly, the positive effect of BB in the UF adhesive mixture on the reduction of formaldehyde emission from plywood panels was also confirmed. Initially, the most significant decrease in formaldehyde release (up to 14%) was measured for the plywood sample, produced with 15% BB. After four weeks, the decrease in formaldehyde was estimated up to 51% for the sample manufactured with 20% BB. The performed differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the findings of the study. As this research demonstrated, BB as a waste or by-product of wood processing industry, can be efficiently utilized as an environmentally friendly, inexpensive alternative to WF as a filler in UF adhesive formulations for plywood manufacturing.

scholarly journals Testing and Assessing Method for the Resistance of Wood-Plastic Composites to the Action of Destroying Fungi

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 697
Author(s):  
Anna Wiejak ◽  
Barbara Francke
Keyword(s):  
Bending Strength ◽  
Test Results ◽  
Negative Effects ◽  
Destructive Effect ◽  
Wood Plastic Composites ◽  
Plastic Composites ◽  
Wood Polymer ◽  
Proposed Modification ◽  
Assessing Method ◽  
Biological Corrosion

Durability tests against fungi action for wood-plastic composites are carried out in accordance with European standard ENV 12038, but the authors of the manuscript try to prove that the assessment of the results done according to these methods is imprecise and suffers from a significant error. Fungi exposure is always accompanied by high humidity, so the result of tests made by such method is always burdened with the influence of moisture, which can lead to a wrong assessment of the negative effects of action fungus itself. The manuscript has shown a modification of such a method that separates the destructive effect of fungi from moisture accompanying the test’s destructive effect. The functional properties selected to prove the proposed modification are changes in the mass and bending strength after subsequent environmental exposure. It was found that intensive action of moisture measured in the culture chamber of about (70 ± 5)%, i.e., for 16 weeks, at (22 ± 2) °C, which was the fungi culture, which was accompanying period, led to changes in the mass of the wood-plastic composites, amounting to 50% of the final result of the fungi resistance test, and changes in the bending strength amounting to 30–46% of the final test result. As a result of the research, the correction for assessing the durability of wood-polymer composites to biological corrosion has been proposed. The laboratory tests were compared with the products’ test results following three years of exposure to the natural environment.

Toxic Effects of Chromium Acetate Hydroxide on Cells Cultivated In Vitro

2001 ◽  
Vol 29 (2) ◽  
pp. 163-177 ◽  
Author(s):  
Emil Rudolf ◽  
Jan Peychl ◽  
Miroslav Červinka
Keyword(s):  
Dna Analysis ◽  
Cell Damage ◽  
Toxic Waste ◽  
Toxic Effects ◽  
Waste Materials ◽  
In Vitro Tests ◽  
High Concentrations ◽  
Discrete Manner ◽  
Chromium Acetate

Many human activities, particularly industrial ones, result in an ever-growing production of toxic waste materials. The dynamics of the toxic effects of chromium acetate hydroxide, which is found in high concentrations in a waste sediment produced in the Czech Republic, were assessed by using a battery of in vitro tests carried out on two cell lines: L-929 (mouse fibroblasts) and Hep 2 (human laryngeal cells). Various markers of cell damage were assessed by phase-contrast, video and fluorescence microscopy, fluorometry, and DNA analysis. Chromium acetate hydroxide, over a concentration range of 1–0.02mol/l induced immediate cell death by fixation, whereas, at 0.002mol/l, the treated cells died in a much slower, more discrete manner. All the detected markers of cell damage, whether immediate or slow, clearly demonstrated that the cells died by necrosis. On the other hand, test concentration of 0.001mol/l appeared to constitute a threshold at which no pathological changes of Hep 2 cells were observed over 96 hours. We conclude that chromium acetate hydroxide has a high toxic potential in vitro, which should be considered when studying the toxicity of waste materials containing it.

scholarly journals Comparative analysis of morpho-physiological features of Triticum vulgare sprouts after exposure to metal nanoparticles

2018 ◽  
Vol 80 (3) ◽  
pp. 190-195 ◽  
Author(s):  
A. M. Korotkova ◽  
O. V. Kvan ◽  
L. A. Bykova ◽  
O. S. Kudryavtseva ◽  
T. S. Videneeva ◽  
...  
Keyword(s):  
Mineral Metabolism ◽  
Cell Damage ◽  
Central Place ◽  
Specific Response ◽  
Triticum Vulgare ◽  
Physiological Processes ◽  
Adaptive Capabilities ◽  
High Concentrations ◽  
Secondary Contamination ◽  
Physiological And Biochemical

In this article violation of the mineral metabolism of plants as a result of secondary contamination with heavy metals (HM), which at high concentrations have a toxic effect on a wide variety of physiological processes, occupies a central place in the problem of the resistance of plant organisms to unfavorable environmental factors. Nanoparticles based on iron, copper and nickel are of considerable interest. The study of the mechanisms of plant adaptation to structurally different nanometals (NM) from the position of changing a number of physiological and biochemical parameters is relevant for a more complete understanding of the adaptive capabilities of organisms in conditions of technogenic nanomaterials. Analysis of the content of photosynthetic pigments allowed the formation of consistent ideas about the selectivity of the effect of nanometals on the components of the pigment system of seedlings, depending both on the composition of the metal and on its concentration. The obtained results serve as additional evidence of the existence of selectivity in the activation of a particular reaction of the plant's antioxidant system, determined by the nature of the nanomaterial. However, a change in the level of ROS in the presence of Ni? and Cu? can be attributed to the non-specific response of plants, since similar changes are characteristic of a variety of stresses of plants and in most cases require further research. In this aspect the main "target" of the action of LF metals was the root system of plants, which determined the interest in identifying mechanisms of phytotoxicity with an emphasis on the study of cell damage in this part of plants.

scholarly journals A New Bioink For Improved 3D Bioprinting Of Bone-Like Constructs

2021 ◽  
Author(s):  
Adam Marsh ◽  
Ehsanul Hoque Apu ◽  
Marcus Bunn ◽  
Christopher H Contag ◽  
Nureddin Ashammakhi ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Rheological Properties ◽  
Cell Damage ◽  
Three Dimensional ◽  
Bone Substitutes ◽  
Tissue Loss ◽  
Major Advance ◽  
3D Bioprinting ◽  
The Matrix ◽  
Inorganic Components

Bone tissue loss can occur due to disease, trauma or following surgery, in each case treatment involving the use of bone grafts or biomaterials is usually required. Recent development of three-dimensional (3D) bioprinting (3DBP) has enabled the printing of customized bone substitutes. Bioinks used for bone 3DBP employ various particulate phases such as ceramic and bioactive glass particles embedded in the bioink creating a composite. When composite bioinks are used for 3DBP based on extrusion, particles are heterogeneously distributed causing damage to cells due to stresses created during flow in the matrix of the composite. Therefore, the objective of this study was to develop cell-friendly osteopromotive bioink mitigating the risk of cell damage due to the flow of particles. Towards this end, we have linked organic and inorganic components, gelatin methacryloyl (GelMA) and Ag-doped bioactive glass (Ag-BaG), to produce a hybrid material, GelMA-Ag-BaG (GAB). The distribution of the elements present in the Ag-BaG in the resulting hybrid GAB structure was examined. Rheological properties of the resulting hydrogel and its printability, as well as the degree of swelling and degradation over time, were also evaluated. GAB was compared to GelMA alone and GelMA-Ag-BaG nanocomposites. Results showed the superiority of the hybrid GAB bioink in terms of homogenous distribution of the elements in the structure, rheological properties, printability, and degradation profiles. Accordingly, this new bioink represents a major advance for bone 3DBP.

Research and Preparation of Silver Free Amorphous Active Brazing Alloy

2015 ◽  
Vol 817 ◽  
pp. 96-103
Author(s):  
Wei Ping Fang ◽  
Yao Yong Yi ◽  
Feng Mei Liu ◽  
Zheng Lin Liu ◽  
Zhen Hua Deng
Keyword(s):  
Bending Strength ◽  
Mechanical Test ◽  
Amorphous Material ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Xrd Pattern ◽  
Spreading Area ◽  
Wetting Ability ◽  
Wetting Contact Angle

A silver free amorphous Cu-35Ti-12Ni active brazing alloy was successfully prepared in this work. The crystallinity, microstructure, and chemical composition were characterized with X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive spectrometry (EDS), respectively. A typical characteristic peak of amorphous material was observed in the XRD pattern. The microstructures and chemical compositions of the silver free amorphous alloy were uniform. Differential scanning calorimetry (DSC) result shows that the amorphous silver free brazing alloy has higher melting temperature than commercial silver brazing alloy (Ag-26.5Cu-1.5Ti). Wetting contact angle and spreading area on Si3N4 ceramic substrate were used to evaluate the wetting ability of brazing alloy. The wetting angle was smaller than 5o, and the spreading area was 141.6 mm2 at 1100°C. The bending strength of silver free brazing alloy/Si3N4 was also carried out. The mechanical test shows that the amorphous Cu-35Ti-12Ni/Si3N4 has higher joint strength (304.7MPa) than the crystal Cu-35Ti-12Ni/Si3N4 (294.7MPa) at room temperature.

scholarly journals Effect of Chromium on Electrochemical and Mechanical Properties of Beta-Al2O3 Solid Electrolyte Synthesized Via a Citrate-Nitrate Combustion Method

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 987
Author(s):  
Jin Shi ◽  
Yongfei Hong ◽  
Chengfei Zhu
Keyword(s):  
Ionic Conductivity ◽  
Solid Electrolyte ◽  
Relative Density ◽  
Bending Strength ◽  
Electrochemical Impedance ◽  
Raw Materials ◽  
Combustion Method ◽  
Scanning Calorimetry ◽  
Al2o3 Phase ◽  
Precursor Powders

The beta-Al2O3 solid electrolyte doped with Chromium was synthesized via a citrate-nitrate combustion method, which started with NaNO3, LiNO3, Cr(NO3)3·9H2O, and Al(NO3)3·9H2O as the raw materials in this paper. The thermal behavior analysis, structure, and ionic conductivity of the beta-Al2O3 solid electrolyte were studied by the thermogravimetry/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Meanwhile, the relative density and bending strength of the samples were also measured. The results showed that with the appropriate Chromium doping, the calcining temperature of the precursor powders was only 1100 °C, the β″-Al2O3 phase content, bending strength, relative density, and ionic conductivity were all improved with a compact and uniform cross section micrograph. The optimized sample contained 94% of β″-Al2O3 phase and exhibited a relative density up to 98.13% of the theoretical density. In addition, it showed a good bending strength (215 MPa) and a satisficed ionic conductivity (0.110 S cm−1 at 350 °C).

Experimental Study on Corrosion Resistance of GFRP in High Temperature and High Pressure Acid Environment

2016 ◽  
Vol 847 ◽  
pp. 466-471
Author(s):  
Zhou Fan ◽  
Jing Wen Fu ◽  
Xiao Ying Yang ◽  
Xiao Gang Hu
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Bending Strength ◽  
Acid Corrosion ◽  
Fiber Reinforced Polymer ◽  
Etch Pits ◽  
Scanning Calorimetry ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Acid Environment

In this paper, the corrosion tests of glass fiber reinforced polymer (GFRP) in high temperature and high pressure acid environment were carried out. The surface morphology and glass transition temperature were observed by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and the mechanical property of GFRP was tested. The results indicated that after being exposed to acid corrosion environment, the structure and organization of GFRP changed, and a variety of defects produced on the surface and interior of GFRP, bending strength and tensile strength of GFRP decreased. The surface analysis also proved that there were some etch pits occurred on the GFRP pipes. Furthermore, their barcol hardness became poor.

scholarly journals Membranes and bile formation. Composition of several mammalian biles and their membrane-damaging properties

1979 ◽  
Vol 178 (1) ◽  
pp. 201-208 ◽  
Author(s):  
R Coleman ◽  
S Iqbal ◽  
P P Godfrey ◽  
D Billington
Keyword(s):  
Guinea Pig ◽  
Bile Salts ◽  
Cell Damage ◽  
Membrane Damage ◽  
Total Content ◽  
Hepatic Cell ◽  
Membrane Composition ◽  
Bile Formation ◽  
Composition And Structure ◽  
High Concentrations

The total content and profile of bile salts and phospholipids are reported for several mammalian biles. Rabbit and guinea-pig biles are characterized by high proportions of conjugated dihydroxy bile salts with respect to trihydroxy bile salts, but contain relatively little phospholipid. Both rabbit and guinea-pig biles exhibit little evidence of hepatic cell damage, even though they are able to cause membrane damage (as evidenced by lysis of human erythrocytes) at low (2–3 mM) concentrations of bile salts; this lytic behaviour is also a property of their predominant bile salts. Addition of phosphatidylcholine to the bile or bile salt is able to decrease the lytic behaviour. Perhaps the most significant observation is that these biles, and their predominant bile salts, are dramatically less lytic towards sheep erythrocytes, indicating that some factor(s) in membrane composition and structure may partly explain the resistance of membranes of the biliary tract to the presence of high concentrations of potentially membrane-damaging bile salts.

Release of endo-lysosomal cathepsins B, D, and L from IEC6 cells in a cell culture model mimicking intestinal manipulation

2009 ◽  
Vol 390 (5/6) ◽  
Author(s):  
Kristina Mayer ◽  
Anna Vreemann ◽  
Hong Qu ◽  
Klaudia Brix
Keyword(s):  
Epithelial Cells ◽  
Extracellular Space ◽  
Inflammatory Responses ◽  
Cell Damage ◽  
Mechanical Damage ◽  
Model System ◽  
Surgical Trauma ◽  
Mechanical Manipulation

AbstractIEC6 cells were used as anin vitromodel system to study the effects of cell damage caused by mechanical manipulation of intestine epithelial cells. We constructed an apparatus that allowed analyzing the consequences of mechanical compression in a standardized and reproducible manner. Manipulation of IEC6 cells induced necrosis rather than apoptosis, and resulted in release of HMGB1, which is known to function as a trigger of inflammatory responsesin vivo. Mechanical damage by traumatic injury of the intestine is accompanied by altered protease activities in the extracellular space, but only little is known about the possible contribution of endo-lysosomal cathepsins. Therefore, we tested the supernatants of manipulated cells in ourin vitromodel system for proteolytic activity and determined release rates by fluorimetric assays. Endo-lysosomal proteases, such as cathepsins B, D, and L, were released from damaged cells within the first 3 h after manipulation. While cathepsin L re-associated with the surfaces of neighboring cells, cathepsins B and D were present in the extracellular space as soluble enzymes. We conclude that our apparatus for mechanical manipulation can be used to approach surgical trauma, thereby focusing on epithelial cells of the intestine mucosa.

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