The first ionization constant from 25 to 200�C and 2000 bar for orthophosphoric acid

1988 ◽  
Vol 17 (3) ◽  
pp. 213-224 ◽  
Author(s):  
A. J. Read
Keyword(s):  
Orthophosphoric Acid ◽  
Ionization Constant

TEM study of order, structure and defects of β and martensite in Cu-Al-Mn shape memory alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 188-189
Author(s):  
J.M. Guilemany ◽  
F. Peregrin
Keyword(s):  
Shape Memory ◽  
Orthophosphoric Acid ◽  
Isopropyl Alcohol ◽  
Metastable Phase ◽  
Characteristic Temperature ◽  
Ethanol Solution ◽  
Order Structure ◽  
Thin Foils ◽  
Polycrystalline Alloys ◽  
Diamond Saw

The shape memory effect (SME) shown by Cu-Al-Mn alloys stems from the thermoelastic martensitic transformation occuring between a β (L2,) metastable phase and a martensitic phase. The TEM study of both phases in single and polycrystalline Cu-Al-Mn alloys give us greater knowledge of the structure, order and defects.The alloys were obtained by vacuum melting of Cu, Al and Mn and single crystals were obtained from polycrystalline alloys using a modified Bridgman method. Four different alloys were used with (e/a) ranging from 1.41 to 1.46 . Two different heat treatments were used and the alloys also underwent thermal cycling throughout their characteristic temperature range -Ms, Mf, As, Af-. The specimens were cut using a low speed diamond saw and discs were mechanically thinned to 100 μm and then ion milled to perforation at 4 kV. Some thin foils were also prepared by twin-jet electropolishing, using a (1:10:50:50) urea: isopropyl alcohol: orthophosphoric acid: ethanol solution at 20°C. The foils were examinated on a TEM operated at 200 kV.

Comparative Study of Acid Etching on Dental Enamel

2018 ◽  
Vol 69 (10) ◽  
pp. 2913-2915
Author(s):  
Daniela Jumanca ◽  
Anamaria Matichescu ◽  
Atena Galuscan ◽  
Laura Cristina Rusu ◽  
Cornelia Muntean
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Experimental Study ◽  
Orthophosphoric Acid ◽  
Dental Enamel ◽  
Acid Etching ◽  
Sealing Material ◽  
Mechanical Bond ◽  
Materials Used ◽  
Scanning Electron

This experimental study aims to analyse the effectiveness of various materials used in demineralisation of dental enamel. This work aims to create a mechanical bond by filling the pegs with sealing material. In order to achieve this goal, five teeth were compared using different concentrations of orthophosphoric acid and exposure times. In this regard, five different tests were performed and the results were analysed using the SEM technique (scanning electron microscopy). These comparative analyses revealed that etching using 35% orthophosphoric acid for one minute and etching using Icon Etch for two minutes were the most effective.

Investigation of Phenolic Content in Five Different Pine Barks Species Grown in Turkey by HPLC-UV and LC–MS

2021 ◽  
Author(s):  
Mehmet Emin Şeker ◽  
Ali Çelik ◽  
Kenan Dost ◽  
Ayşegül Erdoğan
Keyword(s):  
Sample Preparation ◽  
Orthophosphoric Acid ◽  
Phenolic Content ◽  
Reversed Phase ◽  
Uv Detector ◽  
Epicatechin Gallate ◽  
Rp Hplc ◽  
Phenolic Constituents ◽  
Preparation Step ◽  
Very High

Abstract Investigation of phenolic content from different pine bark species grown in Turkey was performed using a reversed-phase high pressure liquid chromatography with ultraviolet (RP-HPLC-UV) method. All phenolic constituents were separated in <26 min on reversed-phase C18 column with gradient mobile phase that consists of orthophosphoric acid, methanol and acetonitrile. Detections were made on an UV detector at 280 nm and at a flow rate of 1 mL/min. Samples were prepared according to Masqueller’s conventional sample preparation method with slight modifications. To avoid the reduction in extraction efficiency the sample preparation step was carried out under argon atmosphere. The linearity of the method was between 0.9994 and 0.9999. The detection limits for the five phenolic constituents ranged from 0122 to 0.324 mg/L. Catechin and taxifolin were found in all pine barks at a concentration of 0.065 ± 0.002–1.454 ± 0.004 and 0.015 ± 0.001–23.164 ± 0.322 mg/g, respectively. Epicatechin was determined in four pine barks between 0.027 ± 0.001 and 0.076 ± 0.002 mg/g, ferulic acid in two pine barks between 0.010 ± 0.001 and 0.022 ± 0.001 mg/g and epicatechin gallate in only one of the pine barks at 0.025 ± 0.001 mg/g. Finally, the total amount of phenolic compounds and antioxidant capacities of the pine barks were found to be very high.

scholarly journals Validation of an HPLC Assay Method for Routine QC Testing and Stability Study of Compounded Low-Dose Capsules of Acetylsalicylic Acid

2018 ◽  
Vol 3 (4) ◽  
pp. 199-206
Author(s):  
Nelly Lonca ◽  
Fabienne Maillard ◽  
Géraldine Leguelinel ◽  
Tahmer Sharkawi ◽  
Ian Soulairol
Keyword(s):  
Acetylsalicylic Acid ◽  
Orthophosphoric Acid ◽  
Low Dose ◽  
Stability Study ◽  
Assay Method ◽  
Stability Studies ◽  
Physicochemical Stability ◽  
Hospital Pharmacies ◽  
Provocation Testing ◽  
Low Dosage

Abstract Background The intolerance to Acetylsalicylic Acid (ASA) can be detected by conducting oral provocation testing (OPT), which is to gradually introduce low doses of ASA. To perform this test, hospital pharmacies compound small batches of different low-dosage ASA capsules. This work aims to validate a method for fast HPLC-UV assay that allows routine quality control and physicochemical stability studies of capsules. Methods The chromatographic separation is performed using a C18 column Kinetex (100 A, 50×4.6 mm, 2.6 µm) equipped with a precolumn C18. Separation is achieved using a mobile phase composed of water-acetonitrile-orthophosphoric acid (68:32:0.2 v/v/v) at a flow rate of 0.8 mL/min and UV detection at 237 nm. Results Validation shows that the method was suitable for routine analysis and could be used to perform stability studies. Conclusions The 5, 25, 100 and 250 mg dosed capsules show acceptable stability over 12 months, while the 1 mg dosed capsule show an unacceptable degradation of more than 15 % after 3 months. Therefore, hospital pharmacy can plan the manufacture of capsules and anticipate the requests of doctors.

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