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Periodontal diseases ranges from simple gum inflammation to serious disease that consists in major damage to the soft tissue and bone teeth support. Periodontal diseases affects the marginal and apical periodontium and results from the interaction between bacterial biofilm and the host response. To determine the concentrations of MMP-8, as a disease marker, in saliva in prosthetic and nonprosthetic, aggressive (AP) and chronic (CP) periodontitis, doxycycline treated patients. 40 patients were distributed into 3 groups: 12 diagnosed with aggressive (AgP), 18 with chronic (CP) periodontitis. Each of these groups was subdivided into 2 subgroups with and without fixed prosthesis. 10 patients were in the normal group. Matrix metalloproteinase 8 (MMP-8) was evaluated before and after systemic doxycycline (Dox) treatment. mean MMP-8 value into the control group was 0.57 ng/mL with a standard deviation (STD) of 0,094 ng/mL. Highest MMP-8 value was established for the nonprosthesis AgP subgroup, before Dox treatment. The highest reduction in MMP-8 levels (40.8%) was between nonprosthesis AgP before Dox treatment and the same group after Doxycycline treamtent. MMP-8 saliva levels are lower than GCF levels, mostly through a dilution mechanism as previous studies had shown. Our study revealed that saliva MMP-8 level is relible marker for AgP but not for CP. Doxycycline treatment, in terms of lowering MMP-8 levels is most effective in patients that have AP and are also wearing fixed.

Isothermal P–x vapor–liquid equilibrium and excess enthalpy (HE) data were experimentally determined for the 10 binary systems hexane, heptane, 1-octene, benzene, toluene, ethanol, methanol, ethyl acetate, dibutyl ether, and dichloromethane with N,N- dimethylacetamide using the static synthetic method and isothermal flow calorimetry, respectively. The experimental data from this work together with data taken from literature were used for the extension of the group contribution method Modified UNIFAC (Dortmund).

For process development and simulation, the group contribution concept can be successfully applied for the estimation of the missing pure component and mixture properties. This concept has the great advantage that only a limited number of group interaction parameters is required. With the support of a company consortium founded 1996 at the University of Oldenburg, the group contribution model modified UNIFAC (Dortmund) for the prediction of phase equilibria and excess properties has been continuously revised and extended. Within the consortium the number of available group interaction parameters has been doubled. At the same time, the reliability of the results was greatly improved, and the range of applicability was extended to ionic liquids, polyethers, and so forth, and systems for which no experimental data are available, e.g., reactive systems. In this paper the group interaction parameters for the sulfur groups sulfones, sulfides, and disulfides are given. Furthermore, the current status of the cons...

The development and design of chemical processes are carried out by solving the balance equations of a mathematical model for sections of or the whole chemical plant with the help of process simulators. For process simulation, besides kinetic data for the chemical reaction, various pure component and mixture properties are required. Because of the great importance of separation processes for a chemical plant in particular, a reliable knowledge of the phase equilibrium behavior is required. The phase equilibrium behavior can be calculated with the help of modern equations of state or gE–models using only binary parameters. But unfortunately, only a very small part of the experimental data for fitting the required binary model parameters is available, so very often these models cannot be applied directly. To solve this problem, powerful predictive thermodynamic models have been developed. Group contribution methods allow the prediction of the required phase equilibrium data using only a limited number of group interaction parameters. A prerequisite for fitting the required group interaction parameters is a comprehensive database. That is why for the development of powerful group contribution methods almost all published pure component properties, phase equilibrium data, excess properties, etc., were stored in computerized form in the Dortmund Data Bank. In this review, the present status, weaknesses, advantages and disadvantages, possible applications, and typical results of the different group contribution methods for the calculation of phase equilibria are presented.

Liquid–liquid equilibria (LLE) of water + acetic acid + dimethyl carbonate were experimentally specified at (298.2, 308.2, and 318.2) K. Each diagram was obtained through specifying binodal curves and tie-lines. The reliability of the experimental tie-line data was calculated by the Othmer–Tobias correlation. The nonrandom two-liquid (NRTL) and unified quasichemical activity coefficient (UNIQUAC) models were used to obtain the binary interaction parameters of the experimental tie-line data. However, universal functional (UNIFAC) and modified UNIFAC methods were used as well to predict the phase equilibrium in the system specified from experimental data using the interaction parameters between CH3, OCOO, COOH, and H2O functional groups. Distribution coefficients and separation factors were assessed for the immiscibility region.

The solubilities of NaCl, KCl, LiCl, and LiBr in pure methanol, ethanol, and acetone were measured over a temperature range from 293.15 to 333.15 K. Furthermore salt solubilities in the mixed solvents (water + methanol, water + ethanol, water + acetone, methanol + ethanol, methanol + acetone, ethanol + acetone) were determined at 313.15 K. For a few systems solubility data are reported for the first time. In a few cases a comparison with published data stored in the Dortmund Data Bank (DDB)(1) showed disagreement. The LIQUAC model was used to correlate the experimental data. The calculated salt solubilities are in good agreement with the experimental results for the systems NaCl + water + methanol and KCl + water + methanol.

This article presents a comparative study about the predictive capability of COSMO-SAC and COSMO-RS(Ol) models with respect to excess enthalpies of various binary systems. Results of the group cont...

This research has been focused on viscosities, vapor−liquid equilibria (VLE), and heat of mixing measurements for water with the following choline-based ionic liquids: choline lactate, choline glycolate, and choline methanesulfonate. Isothermal vapor−liquid equilibria were measured by means of a static VLE apparatus at (303.15, 313.15, and 323.15) K. The experimental VLE data were correlated using the NRTL and UNIQUAC models, and the root-mean-square deviations (rmsd's) are given. Furthermore, the molar excess enthalpies of water + choline glycolate and water + choline lactate ionic liquid systems have been performed at T = (303.15, 315.15, and 323.15) K using a differential scanning calorimeter. The results were fitted to a Redlich−Kister equation to determine the fitting parameters and the mean relative deviations. Viscosities of the binary aqueous systems with choline glycolate and choline lactate have been measured at 293.15 K.

Solid−liquid equilibria (SLE) for the following seven systems have been measured by the visual technique: benzene, toluene, cyclohexane, 1-propanol, methanol, water, and 2-pentanone with e-caprolactone. For the description of the SLE data the NRTL model and the group contribution method Modified UNIFAC (Dortmund) were used.