Phase equilibria of glycerol tristearate and glycerol trioleate in carbon dioxide and sulfur hexafluoride have been investigated. Compositions of the equilibrated phases have been determined experimentally at pressures up to 51 MPa and temperatures (333, 343, and 363) K in a variable volume view cell. For glycerol tristearate-SF6 and glycerol trioleate-SF6 systems, the phase inversion was visually observed at all temperatures. Furthermore, the solid−liquid (S-L) phase transition of glycerol tristearate in CO2 and SF6 was investigated by using a high-pressure view cell. For both systems the three-phase solid−liquid−vapor (S-L-V) line with a temperature minimum in the p−T diagram was observed. High-pressure differential scanning calorimetry (HP DSC) was used to measure and compare the melting point of glycerol tristearate in CO2 with the results obtained by observation in a view cell.
Aerogels of natural polysaccharides possess both biocharacteristics of polysaccharides, such as good biological compatibility and cell or enzyme-controlled degradability, and aerogel characteristics, such as very high porosity and specific surface areas that makes them highly attractive in drug delivery. Biodegradable alginate aerogels were synthesized via a sol-gel process. In the present work two methods of ionic cross-linking were used to prepare alginate hydrogels as monoliths and spheres, which can be further easily converted to high surface area aerogels. The aerogels obtained were further used as drug carriers. We investigated the effect of process parameters, such as starting concentration and viscosity of alginate solution, on synthesis products and on model drug (nicotinic acid) release. The results indicate that by using the internal setting cross-linking method for obtaining monolithic aerogels nicotinic acid was released in a more controlled manner. The aerogels thus obtained also exhibited smaller volume shrinkage than the ones described in other publications. However, with increasing alginate concentration in both types of synthesis more compact and cross-linked aerogels were formed.
In normal circumstances central venous to arterial pCO2 difference is approximately 1 kPa (7.5 mmHg). In shock states it is usually increased. We sought to evaluate the agreement between admission central venous to arterial pCO2 difference and mortality in patients with acute myocardial infarction and cardiogenic shock. We hypothesized that patients with higher central venousto arterial pCO2 difference on admission would have higher mortality. We retrospectively included 30 patients with acute myocardial infarction and cardiogenic shock (mean age 67 +/- 10 years, 73 % men), of which 20 (67 %) died. Nonsignificant differences between survivors and nonsurvivors were observed in age, gender, admission mean blood pressure, heart rate, lactate, hemoglobin, peak troponin I, cardiopulmonary resuscitation, use of therapeutic hypothermia, vasopressors, inotropes, intraaortic balloon pump, and mechanical ventilation. A significant difference between survivors and nonsurvivors was observed in admission central venous to arterial pCO2 difference (1.35 +/- 0.49 kPa vs. 0.83 +/- 0.36 kPa, p = 0.003). In patients with admission central venous oxygen saturation over 70 %, we observed a significant difference in central venous to arterial pCO2 difference between survivors and nonsurvivors (1.33 +/- 0.51 kPa vs. 0.7 +/- 0.3 kPa, p = 0.003) and a nonsignificant difference between survivors and nonsurvivors in patients with admission central venous oxygen saturation under 70 % (1.38 +/- 0.53 kPa vs. 1.25 +/- 0.33 kPa, p = 0.37). Patients with decreased central venous to arterial pCO2 difference on admission seem to be at increased risk of dying even with admission central venous oxygen saturation over 70 %.
This article introduces a new high-pressure process for the gentle drying, micronisation and formulation of high molecular mass gelatine. Spray drying ofgelatine solutions is a well-established process for very low molecular weight gelatine, aqueous solutions containing low gelatine concentrations or gelatine solutions containing viscosity reducing additives. In the introduced process, supercritical CO2 was applied to micronised aqueous gelatine solutions and was then expanded from high pressure into a spraying chamber to remove the water content by extraction and evaporation under moderate conditions. The resulting product was analysed using common powder analysis methods. Aqueous gelatine solutions with a dry mass content of up to 50 wt.-percent with a molecular mass of 156,000 g mol-1 were pulverised and driedwith this process, with only limited degradation by hydrolysis during processing.
The changes in viability and cell morphology, the release of the cellular proteins and the activity alteration of the enzyme alcohol dehydrogenase (ADH) from S. cerevisiae resulting from the exposure to SC CO2 were investigated. Before the treatment of S. cerevisiae in SC CO2, the number of viable cells was cca. 105 colony forming units per mL of cell suspension (cfu/mL). The suspension of the S. cerevisiae culture was incubated in SC CO2 at different pressures (7.5, 15 and 30 MPa) for different treatment times (30–300 min) and at constant temperature (35 °C). The influences of these parameters on total protein concentration, ADH activity and changes in absorbance of nucleic acids (NA) in the suspension of S. cerevisiae during SC CO2 treatment were studied. A decrease in number of living cells of S. cerevisiae in potato dextrose broth (PDB) or in sodium pyrophosphate buffer (SPB) exposed to SC CO2 at all studied pressures was determined when the treatment time was increased. The highest activity of ADH after treatment of the yeast culture suspended in PDB in SC CO2 was detected at a pressure of 7.5 MPa and at the treatment time of 120 min.The use of SC CO2 is a suitable option to achieve cell death and consequently the secretion of proteins and ADH from cells of S. cerevisiae.