No abstract

This paper has analyzed the functioning conditions for the technological system of secondary condensation (TSSC) in a typical ammonia synthesis unit of the AM-1360 series with the use of a system-control approach. The coordinates of control vectors and external disturbances have been determined. An algorithm has been developed for predicting the coordinates of the control vector for the subsystem of decision support under the conditions of external disturbances for such a complex inertial object with high metal consumption as TSSC. The method of mathematical modeling was used to determine, based on the developed algorithm, the patterns and quantitative dependences of the influence of external disturbances such as the temperature of primary condensation and the flow rate of circulation gas on the efficiency of TSSC heat exchange processes. The regularity of increase in the heat flows and coordinates of control vector with an increase in the temperature of primary condensation has been established. The parametric sensitivity of the coordinates of the control vector under the conditions of change in the temperature of the primary condensation has been determined, which, compared with the circulation gas flow rate, exceeds it by more than six times. The executed software implementation of the algorithm employing the MATLAB programming environment makes it possible, owing to the embedded client part (ORC client), free software access to the current data on the technological process. The functional structure of computer-integrated TSSC technology with the proposed correction subsystem under a supervisory control mode has been designed. Correction solutions involving the additional hardware and software based on the programmable logic controller VIPA and SCADA-system Zenon have been practically implemented. The implementation of the developed system ensures the stabilization of the secondary condensation temperature at the regulatory level of −5 °C, which reduces the consumption of natural gas by almost 1 million nm3 per year.

Much attention is presently paid to the study of lipids and lipophilic components of plant origin in order to fabricate medicinal preparations based on them [1,2].In continuation of research in this area, we isolated lipophilic components by the literature method [2] from milk thistle herb (Silybum marianum, Asteraceae) (1), apple leaves (Malus sylvestris, Rosaceae) (2), pear leaves (Pyrus communis, Rosaceae) (3), pressings (4) and leaves (5) of cultured Cabernet-Savignon grape (Vitis vinifera, Vitaceae), and flowers (6) and leaves (7) of elder (Sambucus nigra, Caprifoliaceae). The contents of these were (%): 4.15 (1), 6.9 (2), 2.93 (3), 11.25 (4), 13.24 (5), 4.87 (6), and 6.39 (7).These data show that the contents of lipophilic components are rather high.We also determined the fatty-acid compositions in them and the contents of carotinoids and chlorophylls (Table 1). The saturated acids in all samples were dominated by 16:0 (6.4-30.2%); unsaturated, linoleic (8.4-74.2%) and linolenic (20.8-57.8%), except for 4, 6, and 7, where its amount was insignificant (0.8-2.3%).The carotinoid contents were insignificant. We obtained additional data on the studied samples by measuring three-dimensional fluorescence spectra, which were recorded by three-dimensional scanning spectrofluorimetry in the UV and visible spectral regions on a Hitachi F4010 spectrofluorimeter in the range 350-750 nm. Spectra were processed by constructing three-dimensional plots as before [3].The principal peaks were characteristic of emission from simple phenolic compounds, certain lipids and phospholipids, and a mixture of chlorophylls.A group of peaks typical of emission from flavonoid and coumarin aglycons was also observed. The lipids and lipophilic components were studied as before [2]. The composition of fatty-acid methyl esters was determined by GC on a Chrom-5 chromatograph with a flameionization detector; N 2 carrier gas, flow rate 30 mL/min; rate of H 2 supply 35 mL/min; oxygen, 350 mL/min; temperature of decomposition 186°C, injector 230°C, detector 220°C; stationary phase Inerton AW (0.16-0.20 mm). The stationary phase was treated with dimethyldichlorosilane; mobile phase, diethyleneglycolsuccinate (10% of the stationary phase mass).Fatty acids were identified by comparison of retention times with a mixture of standards [4]. The amounts of chlorophylls and carotinoids were found as before [5].

Foxtail millet (Setaria italica L.) belongs to the family Poaceae (grasses). The plant is widely cultivated in Europe, Asia, Africa, and America. It is included in the Chinese Pharmacopoeia 2000. Our goal was to identify and determine quantitatively sterols in grain of this plant. Raw material was extracted exhaustively with CHCl 3 in a Soxhlet apparatus. The evaporated extract was methylated by acidified methanol and diazomethane. The sterol composition was determined by GC-MS, which enabled us to determine accurately the molecular weights of sterols and to differentiate easily compounds with skeletons consisting of 29, 30, or 31 C atoms [1-3]. A total of 12 sterols was identified by analyzing the grain (Table 1). Table 1 shows that γ-sitosterol (2.781 mg/kg); stigmastanol (1.006 mg/kg); 5-cholesten-3-ol, 24-methyl (0.913 mg/kg); and campesterol (0.867 mg/kg) dominated the sterols. According to the literature the sterols from foxtail millet are also present in other plant oils. Thus, campesterol was isolated from rapeseed, soy, and wheat-germ oils. γ-Sitosterol is one of the main sterols of soy and wheat-germ oils. Stigmasterol occurs also in soy oil. One of the most important sterols is cholesterol or 5-cholesten-3β-ol, which is a precursor in the synthesis of steroidal hormones, bile acids, and vitamin D 3. It is involved in cell membrane formation. Cholesterol is a secondary alcohol and can react with higher carboxylic acids or other compounds, even toxic ones (bacterial toxins, snake and spider venom, etc.), detoxifying them and performing protective functions in the organism. It can stick to walls of blood vessels and decrease their elasticity (atherosclerosis) in cases of disrupted cholesterol exchange.

No abstract