Development of a combined solution of pyrimidine nucleotides with vitamin B6

Pyrimidine nucleotides, namely uridine monophosphate and cytidine monophosphate, play an important role in the cellular metabolism of nerve fibers. The combination of these nucleotides with pyridoxine hydrochloride (vitamin В6) in one dosage form will allow us to fully implement the strategy of the complex neurotropic pharmacotherapy in neuropathies of various origins. To develop a stable solution, an important step at the stage of the composition development is to study the compatibility of active substances (active pharmaceutical ingredients - APIs) in solution. Samples of binary solutions and solutions containing all active substances were prepared and examined. The API interaction was determined by various parameters – changes in color, transparency, рН, the total impurity content, etc. Based on a comprehensive study of the processes of the API dissolution the optimal pH limits of the solution required for the stable existence of a combination of substances with different pH values of the medium have been substantiated and experimentally confirmed. As a result of the research, the optimal pH value of the solution recommended is 4.0-4.8. In the composition of substances the amount of water can be in an adsorbed or crystallized, or combined form. This fact should be taken into account in order to correctly calculate the actual amounts of initial ingredients when preparing the solution. The nature of the water component of APIs was clarified when studying the phase composition of samples on a powder diffractometer. The studies conducted have allowed us to determine the directions of further research for developing the composition of an injection drug. This research is in choosing the optimal buffer system and excipients-antioxidants.

Examination of particulate contamination contents in commercial diesel fuel

The purity of diesel fuel is a crucial issue, in particular in the face of modern injection systems operating under very high pressures with very precisely fitted mating parts. At such pressures and in high temperatures, injectors are particularly exposed to abrasive wear due to the presence of fine, hard abrasive particles in diesel fuel. This article presents the results of diesel fuel contamination with abrasive particles in various size ranges (above 1, 2, 3, 4, 6 and 14 µm) determined in accordance with ASTM D7619 and EN 12662. Fuel samples came from leading manufacturers and were collected at filling stations which are the last links of the distribution chain. Furthermore, all diesel fuels were tested for compliance with all the requirements of EN 590. Analysing the results obtained, the problem of contamination with abrasive particles was found to be present in Poland. Around 37% of the samples tested did not meet the requirements of the Worldwide Fuel Charter (WWFC) in terms of purity class (ISO code 18/16/13 for particles in the range above 4, 6 and 14 µm according to ISO 4406). Violations of the purity class were found mainly for particles in the range over 4 µm. A very large number of particles from the lowest ranges, which are not included in the Worldwide Fuel Charter (above 1, 2 and 3 µm), were also found, and these may cause damage to fuel injection systems. The number of particles in the range above 1 μm in majority of samples exceeded the class 22, and that of those in the range above 2 and 3 μm was mainly between classes 19 and 21. Moreover, no correlation was found between the results of the particulate matter determination (ASTM D 7619) and the total impurity content (EN 12662). Based on the results of the tests carried out, it can be concluded that exceeded number of particles in individual size ranges are not always related to the content of impurities in a form of metallic pulp, impurities from outside the system or the precipitation of enriching additives. Nevertheless, they may be one of the factors contributing to damage to precision fuel injection systems.

Purification of Magnesium by Vacuum Distillation and its Analysis

Based on thermodynamic analysis, the degree of the separation between magnesium and impurities under vacuum was estimated in this paper. It demonstrated that it may be feasible to purify crude magnesium by vacuum distillation on experimental scale. The high purity (99.98 % or 3N8, mass fraction) magnesium (Mg) was obtained through vacuum distillation using 96 % Mg as a raw material under 15 Pa. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) was applied for the analysis of the raw material and the distilled magnesium for 6 impurity elements. The results indicated that the low-volatile impurities such as Fe, Cu, Mn, Pb, Ca could be reduced at the stage of 873K for 30min and the reduction of total impurity content from 34600 ppm (1N6) for crude magnesium to 180ppm (3N8) upon condensate. In conclusion, purification of magnesium was carried out in an efficient high-yield vacuum distillation system designed and fabricated for purifying 1N6 indigenous magnesium to 3N8 (99.98%).

Research on H2S Removal from Yellow Phosphorus Off-Gas through Catalytic-Oxidizing under Low Temperature and Oxygen Content

Research was conducted to illustrate relevant questions about H2S removal from yellow phosphorus off-gas through catalytic-oxidizing method. Following results have been found out. Firstly, Molecule sieve ZMS-5A, activated carbon ZP-1, ZP-2, ZP-3 and ZP-4 were used as carrier to identify their performances on H2S removal, among which ZP-4 was the optimum one. Secondly, among 3 different impregnants tested in experiments, Na2CO3 was the ideal one to be used as active ingredients of catalyst. And 7% was the suitable concentration of Na2CO3 according to experiments. Finally, catalyst made of carrier ZP-4 impregnated with 7% Na2CO3 was assessed comprehensively to investigate its performance on impurity removal of PH3, H2S, SO2, COS, and CS2. After purification total impurity content in yellow phosphorus off-gas was less than 10g/Nm3, which means purified gas can be used as material as mono-carbon chemical industry.

Iron Gettering in CZ Silicon during the Industrial Solar Cell Process

We investigated the impact of using low quality feedstock such as recycled silicon and simplified pulling condition on the performance of CZ silicon solar cells. Groups of wafers carefully chosen from different ingots were analyzed after different solar cell process steps by minority carrier lifetime measurements, by measurements of the interstitial iron content and by measurements of the total impurity content using NAA. Our results show that the main electronic properties of the ingots, namely the carrier lifetime, interstitial iron content and base resistivity are strongly affected by feedstock quality. Surprisingly, high solar cell efficiencies were achieved using highly contaminated silicon. These positive results are due to the beneficial effect of impurity segregation gettering by phosphorous diffusion and aluminum alloying. Post-diffusion gettering by an additional annealing step was demonstrated to enhance the charge carrier lifetime.

Impurities and their Distribution in Temperate Glacier Ice

Total impurity content of salt plus carbon dioxide was estimated as a function of grain size and depth in polycrystalline ice samples cored from a temperate glacier by measuring the electrical conductivity of the melt with air excluded. Conductivity decreased with increasing depth and grain size and ranged from × 10-5 to 0.4 × 10-5 Ω -1 m-1 at 0°C. The conductivity of pure water at 0°C is 0.1 × 10-5 Ω -1 m-1 Studies of the configuration of the three phases and of in situ temperature were also made. Thermodynamic constraints indicate that these impurities are probably concentrated as follows: about 5 mol m-3 in the liquid in the veins along three-grain intersections, roughly 1 × 10-6 mol m-2 associated with grain-boundary area exclusive of veins, and about 0.7 × 10-3 mol m-3 in volume exclusive of veins and grain boundaries. The last of these categories seems to account for most of the impurities in coarse ice (grain size about 20 mm), but all three categories seem significant in fine ice (grain size about 2 mm). Differences in bulk impurity content possibly indicate different histories of flushing by water.

Impurities and their Distribution in Temperate Glacier Ice

Total impurity content of salt plus carbon dioxide was estimated as a function of grain size and depth in polycrystalline ice samples cored from a temperate glacier by measuring the electrical conductivity of the melt with air excluded. Conductivity decreased with increasing depth and grain size and ranged from × 10-5to 0.4 × 10-5Ω-1m-1at 0°C. The conductivity of pure water at 0°C is 0.1 × 10-5Ω-1m-1Studies of the configuration of the three phases and ofin situtemperature were also made. Thermodynamic constraints indicate that these impurities are probably concentrated as follows: about 5 mol m-3in the liquid in the veins along three-grain intersections, roughly 1 × 10-6mol m-2associated with grain-boundary area exclusive of veins, and about 0.7 × 10-3mol m-3in volume exclusive of veins and grain boundaries. The last of these categories seems to account for most of the impurities in coarse ice (grain size about 20 mm), but all three categories seem significant in fine ice (grain size about 2 mm). Differences in bulk impurity content possibly indicate different histories of flushing by water.

The Use of the Direct Reading Spectrometer with dc Arc Excitation and Total Sample Combustion in the Analysis of High Purity Materials

When a dc arc is used for trace analysis on a spectrometer, calibration curves with a pronounced toe due to spectral background are found. For analysis of high purity materials it is most important that linear relationships should be established to ultra-trace levels when total impurity content is specified within the ppm level. A solution to this problem is outlined and the linear relationships obtained for copper, bismuth, and cadmium in high purity silver to 0.1 ppm are shown. An electronic circuit is described that enables these background corrections to be made.

Deviations from Matthiessen's Rule for Platinum

An analysis of the resistivity-temperature relationship down to liquid helium temperatures of 17 platinum resistors as determined in various laboratories shows that deviations from Matthiessen's rule can be classed roughly into three groups. One of them follows the pattern predicted by Sondheimer and Wilson's theory. The other two cannot be fully explained in this way, and may be due to the sensitivity of the electronic band structure of transition metals to small concentrations of impurities. The behaviour of a resistor thus depends on the nature as well as the total amount of impurities and imperfection~. In low temperature platinum resistance thermometry the resistors should be selected with regard to the type of residual impurity as well as total impurity content.