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Freeze-Drying: Principles and Practice
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Steven L. Nail, Larry A. Gatlin
By far the most common buffer system in freeze-dried parenterals is sodium phosphate, since it is present physiologically and has a pK near the pH of normal plasma. A risk associated with freeze-drying of solutions containing sodium phosphate is pH shifts with freezing, discussed below. Other buffer systems used in approved products include acetate, citrate, arginine, histidine, succinate, and Tris (tris-hydroxymethyl aminomethane).
Toxicological Chemistry
Published in Stanley E. Manahan, Environmental Chemistry, 2022
One of the more notable mutagens is tris(2,3-dibromopropyl)phosphate, commonly called “tris,” which was used as a flame retardant in children's sleepwear. Tris was found to be mutagenic in experimental animals and metabolites of it were found in children wearing the treated sleepwear. This strongly suggested that tris is absorbed through the skin and its uses were discontinued.
Polyphosphazenes as Biomaterials
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
Meng Deng, Cato T. Laurencin, Harry R. Allcock, Sangamesh G. Kumbar
Blend miscibility is one of the prerequisites in applications that require controllable and predictable degradation pattern. Efforts have also been made to improve blend miscibility by introducing different side groups containing multiple hydrogen bonding sites in polyphosphazenes. In that direction, Krogman et al. (2009) developed polyphosphazenes having tris(hydroxymethyl)amino methane (Trisma or THAM) side groups and with cosubstitutents glycine ethyl ester and alanine ethyl ester. The THAM side group was linked to the polyphosphazene backbone via the amino function. The polymer has three pendent hydroxyl groups. The polymers form completely miscible blends with both PLAGA (50:50) and PLAGA (85:15) (Krogman et al. 2009). In another study, Krogman et al. have synthesized different glycylglycine dipeptide–based polyphosphazenes (17–20, Figure 4.2) and investigated the miscibility of their blends with both PLAGA (50:50) and PLAGA (85:15) (Krogman et al. 2007). Among them, polymer 18 was found to form completely miscible blends with both PLAGA, which was characterized by SEM, DSC, and attenuated total reflectance infrared spectroscopy (ATR-IR). It was found that the Tg for each blend was lower than that for each parent polymer, implying both polyphosphazenes and PLAGA in the blend acted as plasticizers for each other.
Tunable flow rate in textile-based materials utilising composite fibres
Published in The Journal of The Textile Institute, 2021
Syamak Farajikhah, Sepehr Talebian, Joan M. Cabot, Sepidar Sayyar, Peter C. Innis, Brett Paull, Gordon G. Wallace
Three different solutions, i.e. deionized (D.I.) water (a neutral colon fluid) containing commercially available Pillar Box Red Food Colour (as a non-staining visual maker), sodium chloride (NaCl) aqueous solution (a common component of sweat) and Tris/CHES aqueous solution were chosen for wicking experiments to probe the effect of ionic media. The Tris/CHES is a commonly used biological buffer with low volatility, strong buffering capacity, low conductivity, and is typically used as an electrolyte medium in electrophoresis (Cabot, Duffy, et al., 2016). For wicking tests, the textile structures were pre-wetted with the test solution, and the tubular knitted structure connected between two reservoirs 11 cm apart, Figure 3a. One reservoir was then filled with 1 mL of solution and the amount of fluid transferred to the other reservoir held at the same base height. The flow rate of DI water was determined by the red colour intensity from the volume transferred between reservoirs. Concentration of the red food dye transferred was measured using a visible absorption spectrometer. Calibration curves were prepared for each of the solutions studies. For purely aqueous solutions, a linear trend was shown for different concentrations of red dye, Figure S7a and Figure S7b. To determine flow rate for both NaCl and Tris/CHES solutions, a capacitively-coupled contactless conductivity detection (C4D) (Cabot, Duffy, et al., 2016) technique was utilised. Using C4D a calibration curve for the different concentrations of salts in D.I. water was determined from which the volume transferred could be determined. As depicted in Figure S7c and Figure S7d, a reproducible non-linear voltage response was noted and fitted into a power function calibration curve.