The results of kinetic measurements revealed an accelerating effect of acetazolamide (ACT) on the multistep In(III) ions electroreduction in chlorates(VII) on a novel, cyclically renewable liquid ...silver amalgam film electrode (R-AgLAFE). The kinetic and thermodynamic parameters were determined by applying the DC polarography, square-wave (SWV) and cyclic voltammetry (CV), as well as electrochemical impedance spectroscopy (EIS). It was shown that ACT catalyzed the electrode reaction ("cap-pair" effect) by adsorbing on the surface of the R-AgLAFE electrode. The catalytic activity of ACT was explained as related to its ability to form active In(III)- acetazolamide complexes on the electrode surface, facilitating the electron transfer process. The active complexes constitute a substrate in the electroreduction process and their different structures and properties are responsible for differences in the catalytic activity. The determined values of the activation energy ΔH≠ point to the catalytic activity of ACT in the In(III) ions electroreduction process in chlorates(VII). Analysis of the standard entropy values ΔS0 confirm changes in the dynamics of the electrode process.
The matter constituting the enamels of four types of organisms was studied. The variability of the ions was presented in molar units. It was proven that the changes in water contents of the enamel ...are significantly positively related to changes in Mg; inversely, there is also a strong connection with changes in Ca and P, the main components of bioapatite. The variability in the organic matter has the same strong and positive characteristics and is also coupled with changes in Mg contents. Amelogenins in organic matter, which synthesize enamel rods, likely have a role in adjusting the amount of Mg, thus establishing the amount of organic matter and water in the whole enamel; this adjustment occurs through an unknown mechanism. Ca, P, Mg, and Cl ions, as well as organic matter and water, participate in the main circulation cycle of bioapatites. The selection of variations in the composition of bioapatite occurs only along particular trajectories, where the energy of transformation linearly depends on the following factors: changes in the crystallographic d parameter; the increase in the volume, V, of the crystallographic cell; the momentum transfer, which is indirectly expressed by ΔsinΘ value. To our knowledge, these findings are novel in the literature. The obtained results indicate the different chemical and crystallographic affinities of the enamels of selected animals to the human ones. This is essential when animal bioapatites are transformed into dentistic or medical substitutes for the hard tissues. Moreover, the role of Mg is shown to control the amount of water in the apatite and in detecting organic matter in the enamels.
The introduction of the notion of energy change resulting from the ion exchange in apatites leads to the question: how can some simple isomorphic series be described using the mentioned idea? We ...concentrated on the simple isomorphic series of compounds: apatite, bioapatite, calcite, aragonite, celestine, K-, Zn- and Cu-Tutton's salts. It was demonstrated in all the series, except Tutton's salts, that the change in energy and the change in the crystal cell volume are, in a simple way, dependent on the change in the ionic radii of the introduced ions. The linear relationships between the variations in energy and in the universal crystallographic dimension d were derived from the earlier equations and proven based on available data. In many cases, except the Tutton's salts, linear dependence was discovered between the change in energy and the sinus of universal angle Θ, corresponding to the change in momentum transfer. In the same cases, linear dependencies were observed between the energy changes and the changes in the volumes of crystallographic cells, and mutually between changes in the crystallographic cell volume V, crystallographic dimension d, and diffraction angle Θ.
Among bones building the axial and appendicular skeleton, the mandible is characterized by unique morphological and functional traits. The aim of the study was to evaluate morphological, ...densitometric and mechanical properties of mandible in 5-month-old Polish Merino sheep. Using quantitative computed tomography, volumetric bone mineral density (vBMD) and calcium hydroxyapatite density of the cortical bone (Cb
), mean vBMD (MvBMD) and total bone volume were determined. Using computed tomography cross-sectional scans of the mandible, cross-sectional area, second moment of inertia, mean relative wall thickness and cortical index were determined. Three-point bending test was applied to determine mechanical properties. Serum concentration of insulin-like growth factor I (IGF-I) and bone-specific alkaline phosphatase (BAP) was also measured.
All the investigated morphometric, densitometric and mechanical parameters of the right and left mandibular halves were not significantly different (P > 0.05). There was no correlation of final body weight, MvBMD, Cb
, BAP and IGF-I with all the analyzed parameters of mandible (P > 0.05). However, positive correlations between the other investigated morphometric, densitometric and mechanical parameter of mandible were found (P < 0.05).
Relationships between morphological, densitometric and mechanical parameters of the mandible indicate that the elaborated experimental model may serve for further studies on metabolic responses of skeletal system to physiological, nutritional, pharmacological, toxicological and environmental factors.
Gastrectomy induces severe osteoporosis in humans but its quantitative scale within trabecular and cortical compartments was not estimated. The aim of the study was to determine changes of volumetric ...bone mineral density (vBMD) in lumbar vertebrae (L1-L4) and biochemical bone metabolism markers in serum of patients 1 year after total gastrectomy. The control group consisted of patients (N = 8) subjected to abdominal surgery due to cardiospasmus. Total gastrectomy was performed in the experimental group (N = 6). Volumetric bone mineral density of trabecular and cortical bone of lumbar spine was measured before (baseline) and 1 year after the gastric surgery using the quantitative computed tomography method. Serum concentrations of insulin, insulin-like growth factor-1, tyroxine, interleukin-6, C-terminal telopeptides of type II collagen and bone formation, and resorption markers were determined at baseline and 1 year later, using ELISA, EIA, and IEMA methods. Total gastrectomy induced significant decrease of vBMD values, up to 16.8% and 10.0%, within the trabecular and cortical bone compartments of lumbar spine (P < 0.05). These negative changes of vBMD were associated with significantly increased serum concentration of bone resorption markers such as deoxypyridinoline, pyridinoline, and C-terminal telopeptides of type I collagen, by 13.5%, 32.2%, and 121.5%, respectively (P < 0.05). Neither vBMD nor biochemical bone turnover markers and hormone concentrations were influenced in the control patients. Dramatic bone loss during the first year in gastrectomized patients has proven dynamic osteoporosis progress indicating an importance of treatment interventions in these patients with emphasis on inhibition of intensive bone resorption processes.
The paper discusses the electroreduction of Bi(III) ions in the aspect of expanding the “
cap-pair
” effect.
The “
cap-pair
” rule is associated with the acceleration of the electrode’s processes by ...organic substances. The interpretation of the “
cap-pair
” effect mechanism was expanded to include the effect of supporting electrolyte concentration on the acceleration process and the type of electrochemical active as well as used protonated organic substances. It has also been shown that the phenomena occurring at the electrode/solution interface can influence a change in the dynamics of the electrode’s process according to the “
cap-pair
” rule.
Dental caries is considered to be a modern civilization disease;however, the state of oral health negatively influences psychological and sociological relations in children which leads to feelings of ...discomfort from early age.
The aim of study was evaluation of the association between incidence of dental caries (d3ft index) in preschool children from urban and rural areas, and determining the relationship between dental caries intensity and hygienic habits.
844 children aged 3-6 years from the city and the countryside were examined. The survey was conducted among parents/care givers regarding dental care of children. With parents' consent, the children had a dental examination.
The incidence of caries was recorded at the level of 52.61%, with an average value of 4.31 on the d3ft index; however, for the children from the urban area this ratio amounted to 4.15, and in the countryside it reached the value of 4.7. A correlation was found between age and area of residence of the children and various components of hygienic behavior model.
More than a half of the children had dental caries in combination with a high frequency of unsatisfactory hygiene needs. There is a relationship between oral hygiene habits and age of the children, depending on the place of residence.
Many cases of radicalism, especially violent radicalism, manifest within the context of inter-ethnic conflict and war. Research in this domain has significantly contributed to our overarching ...comprehension of the issue. This form of radicalism is inherently linked to the dynamics of group affiliation. However, our focus here is directed towards the individual motivation driving radical actions. While radical actions may encompass dynamics of group affiliation (e.g., the most radical pro-life activists being members of the Army of God), they also possess a substantial individual component. For instance, numerous attacks on abortion doctors or clinics are categorized as 'lone-wolf terrorism'.
Conventional and modern methods of radiological imaging are often used in the diagnosis of temporomandibular joint disorders, and the CT technique is particularly characterized by an excellent ...visualization of bony structures. The aim of the study was to show the importance and role of CT in the evaluation of TMJ bone structures in both patients with articular disc displacement and in a group of healthy subjects. Both study groups were assessed with the use of the transverse plane. Herein, multi-slice spiral computed tomography was performed in 47 subjects. These individuals were qualified for CT by way of magnetic resonance imaging, due to their being diagnosed with a displacement of their temporomandibular joint disc. The product of our study is presented as a set of tables. These are comparisons of radiological parameters based on the shape, size and location of the mandibular head, in the examined patients, in a control group, and with regard to sex. The results of our work indicate that CT can be successfully used in the imaging of TMJ bone structures, specifically, the condylar process of the mandibular head and the joint socket. However, statistically significant differences of the utilized parameters between patients with articular disc displacement and controls, warrant further analysis of this issue.
Gold is a noble metal with very good chemical resistance. It also does not become oxidized in water or air. Pure gold has a bright yellow color and shine, and it is a heavy, but soft metal with huge ...plasticity and ductility. For many years, gold and its alloys have been recognized as being great prosthetic material in dental practice. In current dentistry, the progress in materials science and galvanoforming techniques have made it possible to create precise restorations utilizing this metal. This pertains both to fixed and removable dentures. Galvanized gold has a range of advantages, among these being biocompatibility, proper marginal tightness, endurance, its esthetic design and the fact that it boasts bacteriostatic features.
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