Comparison and QSAR study of thermodynamic pKBH+ values of benzoylhydrazones determined by UV-Vis spectroscopy

Thermodynamic dissociation constants of fifteen protonated aromatic hydrazones were determined by UV-Vis spectroscopic method, as one of the main methods for determination of pKBH+ values of a weak acids and bases. The stoichiometric pKBH+ values of investigated compounds were determined at three different ionic strengths (0.1, 0.25 and 0.5 mol/dm3) in acidic media (1 < pH < 7). The thermodynamic pKBH+ values were evaluated graphically as an intercept with extrapolation to zero ionic strength of the curve which represents dependence of ionization constants on square root of ionic strength. The obtained results showed that there are no significant differences in the values of thermodynamic dissociation constants of investigated hydrazones with no substituent and metoxy group (–OCH3) on hydrazide part of the molecule. The differences in the pKBH+ values were noticed for hydrazones with nitro group (-NO2) on the benzene ring of benzaldehyde. Nitro hydrazones have lower pKBH+ values, probably due to the influence of the -NO2 group present in their molecule. The obtained pKBH+ values were in accordance with those for similar class of compounds. QSAR study has been made by correlation thermodynamic ionization constants with structure using various physicochemical parameters

DETERMINATION OF MINERALS IN SPRING WATER IN SOUTHWESTERN AND PELAGONIA REGION OF NORTH MACEDONIA

Spring water quality can vary widely with geography, geology, and proximity of pollution sources. In the rural area, the population more often consumes spring water then in urban area. Because of that, there is a need to make a regular assessment of the water quality and prevent its consumption in the case of presence of mineral and organic species in concentrations that are higher than those recommended by the World Health Organization (WHO). In this work spring water from 5 springs in southwestern and Pelagonia region was analyzed for mineral content (Ca, K, Mg, Mn, Fe, Cu) by Atomic Absorption Spectrometry. The obtained results point out that the concentration of manganese in each sample is higher than the maximum acceptable concentration for manganese in drinking water (0.05 mg/L). Especially in the sample 5, where the concentration of manganese is 1.73 mg/L. In this water sample, also the concentration of potassium (80.22 mg/L) is very high compared with the other samples. The concentration of iron is in the range of acceptable values, except for the sample 5 where its concentration is 6.41 mg/L which compared with the maximum acceptable concentration for iron (0.2 mg/L) is very high. The pH value for all samples was in the allowed range

QSAR MODELING OF pKа VALUES OF SULFONYLUREA HERBICIDES

Sulfonylureas are herbicides primarily used for control of weeds in early growth stages of cultivations. Structurally sulfonylureas contain a sulfonyl group with sulphur atom bonded to nitrogen atom of an ureylene group. According side chains there are pyrimidinyl-sulfonylureas and the triazinyl-sulfonylureas. Swiss ADME descriptors have been used to develop QSAR models for predicting the pKa values of selected 27 sulfonlyurea herbicides: 17 pyrimidinyl- and 10 triazinyl-sulfonylurea herbicides. Variable selection methods including stepwise, forward, and best model were employed. Two different approaches were performed to develop a predictive QSAR model: a set with all selected herbicides and a divided set according structure (pyrimidinyl/ triazinyl). QSAR models were analyzed using following statistical parameters: coefficient of correlation, adjusted coefficient of correlation, mean squared error, root mean square error, and Fischer test. Models with four descriptors in both sets of herbicides were statistically better, based on the values of these parameters

VITAMIN C EQUIVALENT ANTIOXIDANT CAPACITY PREDICTION FOR SET OF FLAVONES WHICH INFLUENCE FOOD QUALITY

Flavones are secondary metabolite products in plants and have broad-spectrum effects in both microorganisms and animals with varied structures and functions. The description of antioxidant potential of various chemicals or dietary foods using vitamin C equivalent antioxidant capacity (VCEAC) is preferable compared to other assays. VCEAC values is measure for the antioxidant capacity of the various natural chemicals. The higher the VCEAC value of test compound, the more effective the antioxidant. QSAR (quantitative structure - activity relationships) are theoretical models used to estimate or predict the physicochemical and biologically important activities or properties of biological molecules. A main goal of this investigation was finding QSAR correlation between the experimental VCEAC values and several characteristic calculated descriptors for set of selected flavones. For that reason, physicochemical descriptors (molar refractivity, molar volume, parachor, refractive index, surface tension, density, polarizability and rings plus double bonds equivalent) were selected as independent variables and VCEAC values as dependent values in this QSAR study. According statistical results (R2; R2adj) three-parametric models consist by molar volume, density and polarizability, has been selected as statistically significant. Predicted VCEAC value was compared with the corresponding observed values VCEAC and predictive correlation coefficient (Rpre2) was calculated. The obtained predictive correlation coefficient (Rpre2 = 0.866) confirms our finding

Protonation of citraconic and glutaconic acid in perchloric acid media

The protonation process of citraconic and glutaconic acid in perchloric acid media was followed using the method of UV spectroscopy. The observed changes in the UV spectra of investigated acids confirmed that the protonation process in perchloric acid with concentration from 5 to 10 mol/dm3 occurred. Glutaconic acid behaved as weak organic base in perchloric acid media and existed in its monoprotonated form. On the other hand, citraconic acid existed in its protonated form and as protonated anhydride at higher perchloric acid concentration. Using the absorbance data the thermodynamic dissociation constants were calculated applying the methods of Yates and McClelland, Bunnett and Olsen, and the “excess acidity” function method. The solvatation parameters m, m* and were evaluated, as well. In order to correct the medium effect the method of characteristic vector analysis was applied. The possible site where the protonation may take place was discussed using the partial atomic charge values determined according to AM1 and PM3 semiempirical methods

Normal and reversed phase high performance liquid chromatography of some new 1, 2, 4-triazole derivatives

The retention behaviour and separation ability of normal and reversed phase HPLC with one non-polar and two polar mobile phases, have been studied by measuring the retention constants of a series of newly synthesized 1,2,4-triazole derivatives. The results are discussed in terms of the nature of the solute, eluent and stationary phase

Treatment planning for effective and efficient correction of Class II malocclusion

Objective: The approach of treatment of Class II malocclusion correction depends on several factors such as: the status and pattern of growth, severity of the malocclusion and patient's cooperation. Because of the wide variation found in Class II malocclusions, many different diagnostic decisions weather to extract or not to extract, must be made and treatment mechanics must, of necessity, differ as well. This case reports describe the common diagnostic decisions and the different biomechanics regarding the teeth extractions in patients with Class II malocclusion as well as regarding the dimensions of denture: the anterior limit, the lateral and the vertical limit in patients with different skeletal pattern. Case: The treatment of a Class II malocclusion in case 1 hyperdivergent patient, required extraction of maxillary first premolars to correct the increased overjet, proclined upper incisors, convex profile and skeletal Class II. Case 2 patient with hypodivergent skeletal pattern was treated with camouphlage treatment with maxillary premolar extraction for correction of the jaw relation, retracting the teeth in the extraction space and maintaining the lower incisors position, achieving Angle Class I in the canine region and Angle Class II in the molar region. Case 3 with normal pattern of growth was treated with second maxillary premolars extraction. Due to the fact that the patients were adults, treatment plan could not have included headgears and functional appliances for Class II correction. In all three cases we did not flare the mandibular incisors in order to level the Curve of Spee or to eliminate crowding, due to the fact that their position is very critical. Conclusion: The results included harmonic occlusal relationships with adequate positioning of the teeth in their bony bases and correction of skeletal disharmonies. We can conclude that accurate diagnosis and treatment planning following orthodontic extraction guidelines lead to a long-term stability. Any decision regarding the need for extraction of teeth during orthodontic therapy is not only dependent on the presence or absence of space in the dental arches. Other issues should be evaluated in order to achieve proper malocclusion correction, maintenance or improvement of facial aesthetics and result stability. It is necessary to develop individualized treatment plan with complete evaluation of patient’s dental, facial and skeletal patterns to offer a correct diagnosis and proper treatment plan. We should respect the basic orthodontic principles of treatment planning and do not exceed the biological limitations according to the natural equilibrium. Keywords: Class II malocclusion, Treatment planning, Treatment mechanics, Extraction

Biomechanics in deep bite malocclusion treatment

Objective: Deep bite malocclusion is one of the most common malocclusions in daily orthodontic practice. Proper biomechanics is used to resolve the variety of skeletal and/or dental discrepancies. Aim: To present different cases where the choice of treatment is based in part on the etiology of the deep bite, expected growth, the vertical dimension, relationship of the teeth with the adjoining soft tissue structure and the desired position of the occlusal plane. Material and Methods: Class II division 2 patients, with deep overbite, skeletal Class II, occlusal cant were presented to ilustrate the principles of deep bite cases management. Results: We corrected the deep overbite by extrusion of the posterior teeth or by intrusion of anterior teeth or by combination of both techniques according to the skeletal, dental and esthetic parameters. At th end of the treatment, good teeth alignment and solid, stable occlusion were established. Conclusion: With proper biomechanics our treatment contributed for mandibular forward displacement, reduction of deep bite, reduction of facial convexity and profile improvement. Key words: Deep overbite, extrusion, intrusion, biomechanics

Extraction vs. nonextraction in orthodontic cases

Introduction: Orthodontic treatment helps bring teeth in alignment. Extractions in orthodontics remain a relatively controversial area that we face in our daily orthodontic practice. Objective: The aim of this cases presentation is to elaborate the need of tooth extractions in cases for treating crowding and increased overjet in order to create space in the arches but also to improve facial esthetics and treatment stability compared to non extraction treatment planning. Material and Methods: First case was orthodontic treatment of an adult patient with increased overbite, increased overjet, proclined upper incisors, skeletal Class II. We did camouflage treatment with correction of overjet by retracting the teeth in the extraction space. With Class II elastics use we achieved molar extrusion and opening the bite which is indicated in low-angle patients. Second case was non extraction orthodontic treatment of an adult patient with increased overbite, skeletal Class II. We used bracket positioning play and Class II elastics for intermaxillary correction. Results: After the treatment, we established acceptable, aesthetic and functional occlusion in both patients, based on an accurate diagnosis and treatment plan in conjunction with good patient cooperation, appliance selection and management of the treatment. Conclusion: While we recommend preserving natural teeth whenever possible, extractions of specific teeth are sometimes required in various presentations of malocclusions. Keywords: Orthodontic treatment, extractions, Class II malocclusion, facial esthetics, treatment stability

Orthodontic and Oral Surgery Approach in Cases of Supernumerary Teeth

Introduction: Hyperdontia is an anomaly in the number of individual teeth and is manifested by a greater number of teeth in the jawbones than the normal number. Supernumerary teeth can occur in both generations of teeth, with more frequent representation in the permanent. Two forms of supernumerary teeth can be observed, typical and atypical. Typical supernumerary teeth are very similar in shape to normal teeth (dentes supernumeraria), while atypical supernumerary teeth are usually pointed in shape (dentes accessorya). Aim:The purpose of this lecture is to present the etiopathogenesis, clinical examination, diagnosis, and differential diagnosis, as well as the prognosis, therapeutic treatment, and clinical outcome of supernumerary teeth. Material and Method: The paper will present several clinical cases from its own casuistry, emphasizing the indications and contraindications for operative oral-surgical therapeutic treatment, emphasizing the criteria, conditions and factors that are of great importance in the definitive solution of supernumerary teeth. Results:There are different data on the representation of supernumerary teeth in both the deciduous and permanent teeth. Only those statistical analyzes that are based on clinical and radiological examinations during the primary and permanent dentition of each subject should be considered reliable. Conclusion: In addition to interdisciplinary cooperation, for the realization of oral-surgical interventions, the correct assessment of the expediency and determination of the most suitable time for treatment is of great importance