In vitro Induction of Residual Caries Lesions in Dentin: Comparative Mineral Loss and Nano-Hardness Analysis

2015 ◽  
Vol 49 (3) ◽  
pp. 259-265 ◽  
Author(s):  
Falk Schwendicke ◽  
Kerrin Eggers ◽  
Hendrik Meyer-Lueckel ◽  
Christof Dörfer ◽  
Alexander Kovalev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Acetic Acid ◽  
Ethylenediaminetetraacetic Acid ◽  
Acetic Acid Solution ◽  
Hardness Profile ◽  
Acetate Solution ◽  
Acid Ph ◽  
Residual Caries ◽  
Residual Lesions ◽  
Mineral Loss

Artificially inducing dentinal lesions mimicking those remaining after selective excavation should allow to investigate the effects and limits of such selective excavation, for example regarding the mechanical properties of treated teeth or the remineralisation of sealed residual lesions. Such analyses might otherwise be limited by the variability of natural lesions or ethical and practical concerns. This study compared different demineralisation protocols for their suitability to induce lesions similar to natural residual caries. Twelve natural deep lesions were excavated until leathery dentin remained, and analysed for their mineral loss (ΔZ), lesion depth (LD), mineral loss ratio (R), the slope of the mineral gradient and their nano-hardness profile. Artificial lesions were induced using four different demineralisation protocols (acetic acid pH = 4.95; 0.1 M lactic acid gel pH = 5.0; 0.5 M ethylenediaminetetraacetic acid pH = 7.2; Streptococcus mutans biofilms) and their depths monitored over different demineralisation times. Lesions with depths most according to those of natural lesions were analysed using transversal microradiography. Lesions induced by acetic acid solution did not significantly differ with regards to LD, ΔZ, R and mineral profile. Seven dentin specimens were subsequently submitted to a moderately acidic (pH = 5.3) methylhydroxydiphosphonate-buffered acetate solution for 12 weeks. Natural and artificial residual lesions were similarly deep (mean ± SD: LD = 626 ± 212 and 563 ± 88 µm), demineralised (R = 19.5 ± 4.7 and 29.8 ± 4.1%), showed a flat and continuous mineral gradient (slope = 0.10 ± 0.05 and 0.13 ± 0.06 vol%/µm) and did not significantly differ regarding their nano-hardness profile. The described protocol induces lesions with mineral content and mechanical properties similar to natural residual lesions.

Durability of Red Mud Based Geopolymer Paste in Acid Solutions

2016 ◽  
Vol 866 ◽  
pp. 99-105 ◽  
Author(s):  
Smita Singh ◽  
M.U. Aswath ◽  
R.V. Ranganath
Keyword(s):  
Mechanical Properties ◽  
Acetic Acid ◽  
Fly Ash ◽  
Red Mud ◽  
Acetic Acid Solution ◽  
Strength Loss ◽  
Acid Solutions ◽  
Test Results ◽  
Acid Attack ◽  
Geopolymer Paste

The present investigation is on the effect of red mud on the mechanical properties and durability of the geopolymer paste in sulphuric and acetic acid solution. Red mud and fly ash were used to form the geopolymer paste along with the alkalies. The variation of red mud in the paste composition was from 0% to 90%. Cylindrical shaped specimens of 1 inch diameter and 1 inch height were prepared. The specimens were immersed in 5% sulphuric acid and 5% acetic acid for 1, 7, 14, 28, 56 and 84 days and tested for weight loss, visual deformation, strength loss and colour of the solvent, based on the procedure specified by ASTM C 267 – 01. SEM/EDX Tests were performed on the geopolymer specimens. Test results show that initially, the strength of the geopolymer increased upon the addition of red mud. The strength was maximum when the percentage of red mud was 30%. The maximum strength obtained was 38 MPa for the paste containing 30% red mud using 10M alkali solution as against 31.69 MPa, when only fly ash was used. Geopolymer paste containing 30% and 50% red mud showed better resistance to acid attack. The strength loss was minimum for the samples containing 30% red mud in both inorganic and organic acid i.e. sulphuric and acetic acid.

175. The precipitation of the proteins in milk. I. Casein. II. Total proteins. III. Globulin. IV. Albumin and Proteose-peptone

1938 ◽  
Vol 9 (1) ◽  
pp. 30-41 ◽  
Author(s):  
Samuel J. Rowland
Keyword(s):  
Acetic Acid ◽  
Total Protein ◽  
Trichloroacetic Acid ◽  
Sodium Acetate ◽  
Acetic Acid Solution ◽  
Acid Mixture ◽  
Sodium Acetate Solution ◽  
Acetate Solution ◽  
Maximum Precipitation ◽  
Proteose Peptone

Improved methods have been evolved for the separation of the total protein, casein, albumin, globulin, and proteose-peptone substances of milk.I. The use of acetic acid-sodium acetate solutions for the precipitation of casein is elucidated, and it is shown that the maximum precipitation of casein is rapidly effected from milk samples of varying casein content by the addition to 10 ml. of milk of about 80 ml. of water at 40° C. and 1·0 ml. of 10% acetic acid solution, followed, after 10 min., by 1·0 ml. of N sodium acetate solution.This maximum precipitation was found to be 1·0–1·4% greater than by Moir's method, and 2·4–3·8% greater than by the method of the Association of Oflicial Agricultural Chemists.A procedure is suggested for the determination of casein which avoids the tedious transfer and washing of the precipitate, and gives enhanced ease, accuracy and speed of working.II. The advantages of trichloroacetic acid for the precipitation of proteins in determinations of the total protein and the non-protein nitrogenous substances of milk are discussed.The trichloroacetic acid methods at present in use are shown not to give complete precipitation, and for this a rapid method employing, at room temperature, a final concentration of 12% acid in the milk-acid mixture is recommended.III. An accurate method for the precipitation of globulin uncontaminated with either albumin or casein is described.IV. Methods are given for the precipitation and separation of the albumin and proteose-peptone substances.

Some Approaches to Viscometric Study of Chitosan in Acetic Acid Solution

2016 ◽  
Vol 10 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Valentina Chernova ◽  
◽  
Angela Shurshina ◽  
Elena Kulish ◽  
Gennady Zaikov ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Intrinsic Viscosity ◽  
Acetic Acid Solution ◽  
Conformational State ◽  
Macromolecular Coil ◽  
Degree Of Swelling ◽  
Current Value ◽  
Viscometric Study

Some ways of estimating the values of the intrinsic viscosity of chitosan were analyzed. It was shown that the method of Irzhak and Baranov for estimating the current value of the intrinsic viscosity allows to adequately estimates the conformational state of the macromolecular coil and its degree of swelling.

HPLC-UV Method for Determination of Famotidine from Pharmaceutical Products

2018 ◽  
Vol 69 (2) ◽  
pp. 297-299
Author(s):  
Adriana Nita ◽  
Delia Mirela Tit ◽  
Lucian Copolovici ◽  
Carmen Elena Melinte (Frunzulica) ◽  
Dana Maria Copolovici ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Quantitative Analysis ◽  
Linear Response ◽  
Mobile Phase ◽  
Acetic Acid Solution ◽  
Pharmaceutical Products ◽  
Quantification Limit ◽  
Validation Parameters ◽  
Hplc Analyses

The aim of this study was to develop and validate a rapid, accurate, and exact method for the quantitative determination of famotidine in pharmaceutical products. The HPLC analyses were performed by using a mobile phase containing methanol:1% acetic acid solution=30:7 (v/v), at a flow rate of 0.4 mL/min.The total time of the method was 10 min, and the retention time of famotidine was 4.16 min. The detection was evaluated at l=267 nm. The method has been validated by using different validation parameters. The linear response of the detector for famotidine peak area was observed at concentrations ranging from 0.1 to 0.0001 mg mL-1 , resulting in a correlation coefficient of 0.99998. The values of the detection limit and of the quantification limit are 0.00048 mg mL-1 and 0.00148 mg mL-1, respectively. The method proposed allowed accurate (with a relative error of less than 2%) and precise (RSD values less than 2.0%) determination of famotidine content in pharmaceutical products and can be used for its rapid quantitative analysis.

scholarly journals Influence of artificial aging: mechanical and physicochemical properties of dental composites under static and dynamic compression

2021 ◽  
Author(s):  
D. C. Gornig ◽  
R. Maletz ◽  
P. Ottl ◽  
M. Warkentin
Keyword(s):  
Mechanical Properties ◽  
Water Sorption ◽  
Artificial Aging ◽  
Filler Content ◽  
Dynamic Compression ◽  
The Other ◽  
Chemical Degradation ◽  
Dental Composites ◽  
Compression Tests ◽  
Acid Ph

Abstract Objective The aim of the study was to evaluate the influence of filler content, degradation media and time on the mechanical properties of different dental composites after in vitro aging. Materials and Methods Specimens (1 mm3) of three commercially available composites (GrandioSO®, Arabesk Top®, Arabesk Flow®) with respect to their filler content were stored in artificial aging media: artificial saliva, ethanol (60%), lactic acid (pH 5) and citric acid (pH 5). Parameters (Vickers microhardness, compressive strength, elastic modulus, water sorption and solubility) were determined in their initial state (control group, n = 3 for microhardness, n = 5 for the other parameters) and after 14, 30, 90 and 180 days (n = 3 for microhardness, n = 5 for the other parameters for each composite group, time point and media). Specimens were also characterized with dynamic-mechanical-thermal analysis (compression tests, F =  ± 7 N; f = 0.5 Hz, 1 Hz and 3.3 Hz; t = 0–170 °C). Results Incorporation of fillers with more than 80 w% leads to significantly better mechanical properties under static and dynamic compression tests and a better water sorption behavior, even after chemical degradation. The influence of degradation media and time is of subordinate importance for chemical degradation. Conclusion Although the investigated composites have a similar matrix, they showed different degradation behavior. Since dentine and enamel occur only in small layer thickness, a test specimen geometry with very small dimensions is recommended for direct comparison. Moreover, the use of compression tests to determine the mechanical parameters for the development of structure-compatible and functionally adapted composites makes sense as an additional standard. Clinical relevance Preferential use of highly filled composites for occlusal fillings is recommended.

Compatibility studies of chitosan/PVA blend in 2% aqueous acetic acid solution at 30°C

2010 ◽  
Vol 82 (2) ◽  
pp. 251-255 ◽  
Author(s):  
H.M.P. Naveen Kumar ◽  
M.N. Prabhakar ◽  
C. Venkata Prasad ◽  
K. Madhusudhan Rao ◽  
T.V. Ashok Kumar Reddy ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Acetic Acid Solution ◽  
Aqueous Acetic Acid ◽  
Compatibility Studies ◽  
Aqueous Acetic Acid Solution
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