Tomáš Syrový

The thermodynamic dissociation constants of ambroxol, antazoline, naphazoline, oxymetazoline and ranitidine by the regression analysis of spectrophotometric data

The mixed dissociation constants of five drug acids-ambroxol, antazoline, naphazoline, oxymetazoline and ranitidine-at various ionic strengths I of range 0.01 and 1.0 and at temperatures of 25 and 37 degrees C were determined using SQUAD(84) regression analysis of the pH-spectrophotometric titration data. A proposed strategy of efficient experimentation in a protonation constants determination, followed by a computational strategy for the chemical model with a protonation constants determination, is presented on the protonation equilibria of ambroxol. The thermodynamic dissociation constant pK(a)(T) was estimated by non-linear regression of {pK(a), I} data at 25 and 37 degrees C: for ambroxol p K (a ,1)(T )=8.05 (6) and 8.25 (4), logbeta (21)(T )=11.67 (6) and 11.83 (8), for antazoline p K (a ,1)(T )=7.79 (2) and 7.83 (6), p K (a ,2)(T )=9.74 (3) and 9.55 (2), for naphazoline pK (a ,1)(T )=10.81 (1) and 10.63 (1), for oxymethazoline pK (a ,1)(T )=10.62 (2) and 10.77 (7), pK(a,2)(T)=12.03(3) and 11.82 (4) and for ranitidine p K (a ,1)(T )=1.89 (1) and 1.77 (1). Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates to be found.

Determination of the number of light-absorbing species in the protonation equilibra of selected drugs

The determination of the number of components in a mixture is an important tool for qualitative and quantitative analysis in spectroscopy. The accuracy of nine selected indices for an estimation of the number of components that contribute to a set of spectra was critically tested on experimental data sets of protonation equilibria of four drugs using the INDICES algorithm in S-Plus. Methods are classified into two categories: precise methods based on a knowledge of the instrumental error of the sabsorbance data, sinst(A), and approximate methodsrequiring no such knowledge. Indices of precise methods predict the correct number of components, even the presence of a minor one, when the quality of data is high and instrumental error is known. Improved identification of the number of species uses the second or third derivative function for some indices, namely when the number of species in the mixture is higher than four and when, due to large variations in the indicator values even at logarithmic scale, the indicator curve does not reach an obvious point where the slope changes. The number of variously protonated components and their dissociation constants for four drugs—mycophenolate, ambroxol, silybin and silydianin—at 25 ◦ C were determined using SQUAD(84) regression and INDICES principal component analysis of the pH-spectrophotometric data. A proposed strategy of efficient experimentation in protonation constants determination, followed by a computational strategy, is presented with the goodness-of-fit tests for various regression diagnostics enabling the reliability of parameter estimates to be accessed.

Number of species in complexation equilibria of SNAZOXS or Naphtylazoxine 6S and Cd2+, Co2+, Cu2+, Ni2+, Pb2+ and Zn2+ ions by PCA of UV–vis spectra

A critical comparison of the various PCA methods on the absorbance matrix data concerning the complexation equilibria between SNAZOXS and Cd(2+), Co(2+), Cu(2+), Ni(2+), Pb(2+) and Zn(2+) or Naphtylazoxine 6S and Cd(2+), Cu(2+), Ni(2+) and Zn(2+) at 25 degrees C is performed. The number of complex species in a complex-forming equilibria mixture is the first important step for further qualitative and quantitative analysis in all forms of spectral data treatment. Therefore, the accuracy of the nine selected index functions for the prediction of the number of light-absorbing components that contribute to a set of spectra is critically tested using the principal component PCA algorithm INDICES in S-Plus software. Four precise methods based upon a knowledge of the experimental error of the absorbance data and five approximate methods requiring no such knowledge are discussed. Precise methods always predict the correct number of components even a presence of the minor species in mixture. Due to the large variations in the index values and even at logarithmic scale they do not reach an obvious point where the slope changes. An improved identification with the second or third derivative and derivative ratio function for some indices is preferred. Behind the number of various complexes formed the stability constants of species ML, ML(2), (and ML(3), respectively) type logbeta(11), logbeta(12), (and logbeta(13), respectively) for the system of SNAZOXS (ligand L) with six metals (the standard deviation s(logbeta(pq)) of the last valid digits are in brackets) Cd(2+) (4.50(3), 8.36(7)), Co(2+) (5.75(6), 9.79(9), 13.05(2)), Cu(2+) (6.69(6), 11.40(7)), Ni(2+) (6.44(8), 10.91(11), 15.07(10)), Pb(2+) (5.63(5), 9.97(9)) and Zn(2+) (5.11(3), 8.84(5)) and for system of Naphtylazoxine 6S with Cd(2+) (6.08(4), 11.44(7), 16.06(11)), Cu(2+) (7.80(8), 13.41(14)), Ni(2+) (6.35(12), 11.43(19), 16.68(24)) and Zn(2+) (7.01(8), 12.65(15)) at 25 degrees C are estimated with SQUAD(84) nonlinear regression of the mole-ratio spectrophotometric data. The proposed strategy of an efficient experimentation in a stability constants determination, followed by a computational strategy, is presented with goodness-of-fit tests and various regression diagnostics able to prove the reliability of the chemical model proposed.

Printed passive components for RFID labels

This paper deals with the research and development of printed flexible capacitors and inductors predominantly designed for the construction of RFID labels. These printed RF passive components are required for the construction of fully printed low cost passive RFID labels. The passive components are directly printed on PET substrate by the screen printing technique. The printing process was optimized in order to achieve a high yield and good electrical parameters at the frequency of 13,56 MHz. Electrical parameters of printed capacitors, such as impedance to frequency characteristic, capacity to temperature characteristic, capacity to bias voltage characteristic were measured in detail. The bending tests were also performed for verifying of printed capacitors flexibility. The performance of capacitors was verified in the real sample of resonant circuit at 13,56 MHz.

Producing two-component thermochromic pattern by means of offset printing

The objective of this work was to produce an antifraud pattern comprising two parts. One part was designed as a chosen CMY combination with overprinted thermochromic ink, and the other one was designed as a CMYK combination, to match the color of the part with thermochromic ink. An offset printing press Roland 500 with five inking units was used. The process included profiling the CMYK printing press with no overprint and profiling the CMYK printing press with thermochromic magenta and thermochromic blue ink overprint respectively. For the chosen combination of CMY with thermochromic ink overprint, a CMYK simulation using color management was computed. The thermochromic ink overprints and the corresponding CMYK simulations were printed, and obtained color match was evaluated. Even though average color differences values were higher than 3.5, the visual perception of color match can be positively influenced by the pattern design.

Application of Ink-Jet Printing and Spray Coating for the Fabrication of Polyaniline/Poly(N-Vinylpyrrolidone)-Based Ammonia Gas Sensor

We report on the preparation of thin conducting films from the poly (N-vinylpyrrolidone) stabilized polyaniline dispersions for the ammonia gas sensor applications. The dispersion is water-based and prepared by means of relatively simple chemical oxidation polymerization of aniline. Two processes were used for the ink deposition, the ink-jet printing and the spray-coating technique. With the former one, the ink was at first tested on the poly (ethylene terephthalate) foil to find a suitable combination of ink formulation and print parameters. After that, the final ammonia gas sensors were fabricated by both deposition techniques and compared. The aspects of the ink preparation and alteration, as well as the active layer properties, are analyzed by means of UV-vis spectroscopy, optical microscopy, atomic force microscopy, profilometry and electrical measurements. The results obtained from each deposition technique are discussed. In both cases, the sensitivity to the ammonia gas has been demonstrated, making the proposed ink in combination with the two named deposition processes feasible for the potential large-area sensor production.

Number of species in complexation equilibria of o-, m- and p-CAPAZOXS with Cd2+, Co2+, Ni2+, Pb2+ and Zn2+ ions by PCA of UV-vis spectra.

A critical comparison of the selected derivative principal component analysis (PCA) methods on the absorbance matrix data concerning the complexation equilibria between o-CAPAZOXS and Cd(2+), Pb(2+) and Zn(2+) or m-CAPAZOXS and Cd(2+), Co(2+), Ni(2+) and Zn(2+) or p-CAPAZOXS and Cd(2+) and Zn(2+) at 25 degrees C is provided. As the number of complex species in a complex-forming equilibria mixture is an important step in spectral data treatment, the nine selected index functions for the prediction of the number of light-absorbing species that contribute to a set of spectra is critically tested by the PCA. An improved identification with the second SD(AE) or third derivative TD(AE) and derivative ratio function ROD(AE) for the average error criterion AE is preferred. After the number of various complexes formed the stability constants of species ML, ML(2) (and ML(3), respectively) type log beta(11), log beta(12) (and log beta(13), respectively) for the system of o-CAPAZOXS (ligand L) with the metals (the standard deviation s(log beta(pq)) of the last valid digits is given in brackets) Cd(2+) (6.39(5) and 11.51(9)), Pb(2+) (4.24(2) and 9.01(2)) and Zn(2+) (5.18(7) and 9.06(10)) and for the system of m-CAPAZOXS with Cd(2+) (6.59(20) and 11.51(32)), Co(2+) (7.19(6) and 12.19(8)), Ni(2+) (7.64(7) and 13.39(12)) and Zn(2+) (4.83(3) and 9.57(3)) and for the system of p-CAPAZOXS with Cd(2+) (6.44(5), 10.99(10) and 14.57(25)) and Zn(2+) (6.84(16), 13.05(29) and 18.74(43)) at 25 degrees C are estimated using SQUAD(84) nonlinear regression of the mole-ratio spectrophotometric data. The computational strategy is presented with goodness-of-fit tests and various regression diagnostics capable of proving the reliability of the chemical model proposed.