production of selected secondary metabolites in transformed ...

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concentrated HCl to pH ~ 1 and leaved in refrigerator overnight. After the centrifugation (10 min., 4000 rpm, cooling for 15 °C) the supernatant was poured out and the gel was washed three times by deionized water. Each washing was followed by centrifugation, the last one took 30 minutes. Finally the gel was deposited in dessicator with water to stabilize its humidity. The picture of prepared gel sample is shown on the Fig. 1. The HA sample was characterized by means of table 1 Elementary analysis results content in dried element ash-free HA [atomic %] H 42,12 C 41,16 O 15,64 N 0,91 S 0,17 the elementary analysis (Microanalyser Flash 1112, Carlo Erba), ash content analysis (sample contained 6.8 weight % of water and 28.5 weight % of ash), and UV–VIS and FT–IR spectral analysis (Hitachi U 3300 and Nicolet impact 400 respectively). From the exact results of these analyses, which are listed elsewhere ([4]), it is clear, that used HA were of high degree of humification. The humic gel sample was analyzed for its solid matter content (14.5 weight %), total gel acidity was determined by potentiometric titration (gel contained 8.12 mmol acid equivalents per 1 g of HA). The FT–IR spectroscopy analysis of dried gel sample results in fact that no chemical structure changes occur while gelation of HA. Diffusion experiment was divided into several parts; in the first one the pre-determined (see [3]) value of the diffusion coefficient of copper(II) ions in humic gel was verified by the stationary diffusion from the saturated copper(II) chloride solution. In detail, experimental procedure is listed in [4]. In all remaining parts the non-stationary diffusion was studied. All experiments took place in apparatus presented on Fig. 2. Humic gel was packed into plastic tube as 5 cm long cylinder and 2 ml of both copper ions solution and deionized water were filled into side containers. First of all diffusion dependency on Cu(II) initial concentration in solution was monitored by changing the initial concentration of CuCl2 solution placed in the apparatus container, while the duration of experiment was maintained at 24 hours. After the end of the experiment, each gel sample was sliced and each slice was separately extracted by 1 mol.dm –3 HCl. By the UV–VIS quantification of Cu(II) content in each extract, the concentration profile of the gel cylinder and the total diffusion flux across the solution–gel interface were determined. Next part deals with the influence of time duration of diffusion experiment. The 1 day, 3 days and 5 days periods have been chosen. The experiment was repeated for three Cu(II) initial concentration values: 0.1 mol.dm –3 , 0.3 mol.dm –3 and 0.6 mol.dm –3 . Following experimental technique was adopted from previous experiment without changes. In the last part, the influence of other copper(II) solution properties has been investigated. The influence of the type of copper(II) salt anion was studied by using CuCl2, Cu(NO3)2, Cu(II) plugged solution containers HUMIC GEL plastic tube H2O Fig. 2 Scheme of the aparatus used in all diffusion eperiments Sborník soutěže Studentské tvůrčí činnosti Student 2006 a doktorské soutěže O cenu děkana 2005 a 2006 Sekce DSP 2006, strana 224
CuSO4, Cu(ClO4)2 and Cu2P2O7 of the same Cu 2+ concentration (0.1 mol.dm –3 ) as a stock solution for diffusion experiments of the same time duration (24 hours). Finally, the solution pH – dependency and solution ionic strength dependency of the diffusion process was checked by diluting CuCl2 salt using the differently concentrated hydrochloric acid and sodium chloride, respectively. For all of these experiments the same Cu 2+ concentration (0.1 mol.dm –3 ) as well as the time duration (24 hours) was used and the same experimental technique (see above) was adopted. RESULTS AND DISCUSSION The value of calculated effective diffusion coefficient of copper(II) ions in humic gel was 7.96×10 -10 m 2 .s –1 . This value is in good agreement with the one pre–determined by another experimental method (see [3]) and was used for all following calculations. As can be seen on Fig. 3 and Fig. 4, total diffusion flux of Cu 2+ through solution–gel phase interface linearly increases with the initial concentration of copper(II) in solution and with the square root of time duration of diffusion experiment. The later dependency is however much more complicated; the nonzero intercept of the regression line indicates that the linearity is just illusory and in fact the dependency is curved. Klučáková et al. in [5] stated the equation for the total diffusion flux across the solution–gel interface: ε c D τ 0 g m = (1) 1+ ε D / π g D in which m stands for the total diffusion flux, c0 is initial concentration of the ion in solution, τ is the time duration of the diffusion, ε is ratio of ion concentration in the gel and in the solution in final equilibrium (at the “end of diffusion”), Dg and D is diffusion coefficient of cupric ions in humic gel and in solution, respectively. Following this equation the value of ε was calculated from total diffusion flux corresponding to c0 and τ values. It was found that for the same duration of diffusion experiment this value is constant for different initial concentrations of the solution but it varies for different duration of experiment (Fig. 5). This fact could be explained by the apparatus construction (small solution volumes – gel weight ratio) or by the time–consuming formation of some stable structural or chemical complexes between gel and ions. This affects the mobility of ions (retention of ions can lead up to their immobilization in gel) and their equilibrium in gel and solution. This fact could explain mentioned deformation of total flux time dependency as well. The knowledge of the ε value allows the calculation of theoretical y = 6.454E-03x concentration profiles of the copper (II) R ions in the humic gel (used mathematical apparatus is presented in detail in reference [5]) for individual experiment conditions (initial concentration, time duration). The example on Fig. 6 shows very good agreement between calculated and measured concentration profiles. 2 50 40 = 1.000E+00 30 20 10 0 0 2000 4000 6000 8000 total flux [mol.m -2 ] c0 [mol.m -3 ] Fig. 3 The total diffusion flux dependency on the initial concentration of Cu 2+ in the solution (diffusion duration 24 hours) Sborník soutěže Studentské tvůrčí činnosti Student 2006 a doktorské soutěže O cenu děkana 2005 a 2006 Sekce DSP 2006, strana 225
Page 1 and 2: PRODUCTION OF SELECTED SECONDARY ME
Page 3 and 4: containing ampicillin, IPTG and x-g
Page 5 and 6: THE SIMPLE METHOD FOR THE RECOGNITI
Page 7 and 8: Figure 1 Negative-ion mode MALDI-TO
Page 9 and 10: Table 1 Evaluation of negative-ion
Page 11 and 12: Fig. 1: Scheme of the hydride gener
Page 13 and 14: [4] H. Matusiewicz, M. Kopras, J. A
Page 15 and 16: - are hypotriglyceridemic; - exhibi
Page 17 and 18: HYDROPHOBIZED SODIUM HYALURONATE IN
Page 19 and 20: spectrophotometer (AMINCO-Bowman, S
Page 21 and 22: Hyaluronate derivatives showed with
Page 23 and 24: copolymers were additionally functi
Page 25 and 26: Each micelle has a hydrophobic core
Page 27: STUDY OF THE COPPER(II) IONS NON-ST
Page 31 and 32: total flux [mol.m -2 ] 0.7 0.65 0.6
Page 33 and 34: number of free radicals is very low
Page 35 and 36: Differences can be caused by severa
Page 37 and 38: MEASUREMENT OF THERMOPHYSICAL PROPE
Page 39 and 40: The typical time responses of tempe
Page 41 and 42: Figure 4 illustrates the typical de
Page 43 and 44: sodium sulphate and filtered to a 5
Page 45 and 46: Compare all tested evening primrose
Page 47 and 48: IMPROVED FLUORIMETRIC DETERMINATION
Page 49 and 50: Al F i 80 70 60 50 40 30 20 10 0 0
Page 51 and 52: F i 60 50 40 30 20 10 Data UCL LCL
Page 53 and 54: PHYSICAL-CHEMICAL ASPECTS OF PAINT
Page 55 and 56: Finally, the solubility parameter o
Page 57 and 58: Study of the influence of different
Page 59 and 60: Fig.1: Chemical structures of pI ma
Page 61 and 62: Identification of pI markers - Firs

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