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microenvironment polarity is well known and described (Aguiar 2003). We evaluated experimental data using non-linear fitting with Boltzman’s curve with four parameters – maximum (a), minimum (b), inflex point (x0), and width of the gradient (Δx) (Equation 1). We voted and subsequently confirmed the “x-coordinate” of the inflex point as the cac value. For the confirmation we used the perylene’s fluorescence measurements. a − b y = + b 1) ( 0 x − x ) Δx 1+ e Perylene, dibenz[de,kl]anthracene, is also the even and alternating hydrocarbon (Figure 2b). The perylene’s measurements are quite simple for evaluation. The fluorescence intensity of the perylene rise with the number of non-polar domains in the hHA’s solution. Earlier than domains are presented in solution no fluorescence is observed. When domains are formed we observe sharp increasing of the fluorescence. These two trends can be fitted by the linear curves and the x-coordinate from their point of intersection defines the cac value directly. a) b) Figure 2 Fluorescence probes - a) pyrene b) perylene MATERIALS AND METHOD The hyaluronan and its derivatives were obtained from CPN Ltd. (Dolní Dobrouč, Czech Republic). Hyaluronans were in these molecular weights: 97, 560, and 1630 kg·mol -1 . Derivatives were in molecular weights 134, 183, 360, and 1470 kg·mol -1 , respectively, and theirs substitution degrees were in range from 10 to 70 %. The substitution degree is defined as the ratio of the number of the monomer with and without the alkyl chain per polymer chain, and it was determined from 1 H NMR spectra. All molecular weights were determined by SEC-MALLS (Mlčochová, 2006). Pyrene and perylene were obtained both from Fluka GmbH. Acetone p.a. was obtained from Lachema Ltd. The samples were dissolved in doubly distilled water to the concentration 2 g l -1 . This stock solution was stabilized by addition sodium azide (NaN3) in final concentration 10 -3 M. Sample nomenclature. The samples are named in correspondence to their characteristics. The first come alkyl-type abbreviation, next are basic molecular weight (before derivatization), and after the solidus the substitution degree. For example D 134/10 means C10-derivate with the molecular weight 134 kg·mol -1 and the substitution degree 10 %. Fluorescence Method. The acetone stock solutions of the pyrene and perylene were prepared. Probes stock solution was introduced into a flask and acetone was evaporated. The stock solution of hHA was introduced into a flask with evaporating probe, it was diluted to the desirable concentration, and the resulting solution was sonificated during 4 hours and stored during next 20 hours. The fluorescence emission spectra were monitored with a luminiscence Sborník soutěže Studentské tvůrčí činnosti Student 2006 a doktorské soutěže O cenu děkana 2005 a 2006 Sekce DSP 2006, strana 214
spectrophotometer (AMINCO-Bowman, Series 2) at 293.15 ± 0.1 K. The excitation and emission slit widths were set to 4 nm, where for pyrene and perylene the excitation wavelength was 335 nm and 408 nm, respectively. By the pyrene way, the ratio of the fluorescence intensity at 373 nm (I1) and at 383 nm (I3) was plotted against the logarithm of the concentration. These data was fitted by sigmoid curve with the nonlinear curve fitting with Origin 75. From non-linear fitting we obtain two possible cac points - directly cac1-point as the inflex point. Second one, cac2-point, is defined as cac2 = x0 + 2Δx . 2) Perylene’s data evaluation was based on fit of two linear trends. From equations related to these linear curves was evaluated “x-coordinate”, cacPe, of the point of intersection. Fluorescence (a.u.) 1 0.8 0.6 0.4 0.2 0 Fluorescence (a.u.) RESULTS AND DISCUSSION It is useful to use only one probe for the CAC determination. Pyrene’s data contain not only information about aggregation but even polarity information. Because pyrene is partially water soluble, it is necessary to know exactly which cac-point is the right. F int. norm. 250 300 350 400 450 500 1.0 0.8 0.6 0.4 0.2 I3 a) Emission 0.8 b) Excitation 0.6 I1 wavelength (nm) 1 0.4 0.2 0 Excitation Emission 320 370 420 470 520 570 wavelength (nm) Figure 3 Spectral properties of the pyrene (a) and the perylene (b) Perylene Pyrene R 2 = 0.9702 R 2 = 0.9998 0.0 0.8 -3 -2 -1 0 1 Log C 1.6 1.4 1.2 1.0 I 1 /I 3 Figure 4 The plot of the normalized integral fluorescence and the I1/I3 vs. the Log C. The perylenes data are separate and fit with the linear curves. The pyrenes data are fit by sigmoid curve with marked cac1 (×). The point of intersection (↑) from perylenes dependence(x-coordinate - 0.747) is identical with the pyrenes cac1 point (x-coordinate - 0.750). Sborník soutěže Studentské tvůrčí činnosti Student 2006 a doktorské soutěže O cenu děkana 2005 a 2006 Sekce DSP 2006, strana 215
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: HYDROPHOBIZED SODIUM HYALURONATE IN
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 and 28: STUDY OF THE COPPER(II) IONS NON-ST
Page 29 and 30: CuSO4, Cu(ClO4)2 and Cu2P2O7 of the
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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