Experimental and Theoretical Study Of UV-Vis Spectra of Schiff Bases

The UV-Vis properties of ten Schiff bases were systematically investigated. The time-dependent density functional theory (TDDFT) approach in combination with the B3LYP functional was used for simulation of UV-Vis spectra of examined compounds. The shapes of the Kohn-Sham molecular orbitals involved in electronic transitions were misleading. To provide better understanding of distribution of electron density natural bond orbital (NBO) analysis was used. NLMO clusters were constructed and they represent a part of a molecule characterized with eminent electron density. The TDDFT and NBO theories are complementary, and the results from these two approaches are combined to interpret the UV-Vis spectra

Oral Health in 12- and 15-Year-Old Children in Serbia: A National Pathfinder Study.

The aim of the paper is to present the oral health profile of 12- and 15-year-old schoolchildren in Serbia. Basic Methods for Oral Health Surveys of the WHO were implemented to record: Decayed, Missing, and Filled Teeth/Surfaces Index (DMFT/DMFS), gingival bleeding, enamel fluorosis and other structural anomalies, dental erosion, dental trauma, and oral mucosal lesions. In addition, Silness and Löe plaque index and orthodontic status were assessed. A total of 36% of 12-year-olds and 22% of 15-year-olds in Serbia were caries-free. The mean DMFT was 2.32 ± 2.69 for 12-year-olds and 4.09 ± 3.81 for 15-year-olds. DMFT was made up largely by the decayed component. Gingival bleeding was present in 26% of examined 12-year-old and 18% of 15-year-old children. Dental plaque was observed in 63% of both 12- and 15-year-olds. Fluorosis, structural anomalies, dental erosion, dental trauma, and oral mucosal lesion were rarely detected. Low prevalence of malocclusions was found. Oral disease is still a common public health problem among schoolchildren in Serbia. A significant increase in the prevalence of caries disease between 12- and 15-year-old groups implies that preventive care for adolescents requires special attention. Corrective actions and reforms to the current school-based oral health prevention program are needed to further improve oral health in Serbian children

Molecular docking study on the interaction of Rhodopsin-like receptor with tetra-coordinated gold(III) complex

The pharmacologic properties of gold compounds have been known since the end of the 19th century. In the last decade, gold complexes have received increased attention due to the variety of their applications. Rhodopsin-like receptors are a family of proteins that belong to the largest group of G protein-coupled receptors (GPCRs). In this paper, the molecular interactions between active binding sites of the Rhodopsin-like receptor (RLR) and synthesized gold(III) complex ([Au(DPP)Cl2]+ where DPP=4,7-diphenyl-1,10-phenanthroline) were investigated by molecular docking simulations. The crystal structure of investigated receptor RLR (PDB ID: 4A4M) was extracted from RCSB Protein Data Bank in PDB format. The native bound ligand (11-cis-retinal) was extracted from receptor and binding pocket analysis was performed. Re-docking was performed with the gold(III) complex to generate the same docking pose as found in co-crystallized form of receptor. The binding energy of gold(III) complex to RLR was found to be -35.35 kJ/mol, as opposed to 11-cis-retinal which of about - 40.5 kJ/mol. The obtained results of revealed that gold(III) complex binds at the same binding pockets to RLR, as well as native bound ligand, by weak non-covalent interactions. The most prominent interactions are hydrogen bonds, alkyl-π, and π-π interactions. The preliminary results suggest that gold(III) complex showed good binding affinity against RLR, as well as native bound ligand, 11-cisretinal, as evident from the free binding energy (ΔGbind in kJ/mol).The authors are grateful to the Ministry of Education, Science and Technological Development of the Republic of Serbia (Agreement No. 451-03-9/2021-14/200378 and Agreement No. 451-03-68/2021-14/200122) for financial supportPublishe

Las actitudes de los padres sobre la adaptación de los niños a la institución preescolar

The aim of this research study is to examine parents´ attitudes towards the process of children´s adjustment to a pre-school institution, as well as towards separation difficulties which are encountered when a child starts attending kindergarten. Research results provide answers to whether parents are familiar with the problems manifested in the children´s adjustment process, as well as with the possibilities of successfully overcoming such issues. The research included 763 parents of pre-school children in the territory of Serbia. The differences in parents´ attitudes have been analysed relative to their sex, education and age. In the course of research the authors resorted to a five-point Likert scale composed of 16 items grouped into the following categories: factors which influence the process of adjustment, indicators of a successfully completed adjustment process and methods for overcoming the issues raised in the process of children´s adjustment to a pre-school institution. Parents believe that children´s satisfaction when they attend kindergarten is a more significant indicator of a successfully completed adjustment process relative to the absence of crying and deprecation, as well as that for the purposes of overcoming the difficulties which occur when children start attending a pre-school institution parents most frequently introduce preschool teachers to their child´s habits and traits, and later talk with the child about events in the kindergarten. Research results indicate the presence of statistically significant differences in parents´ attitudes relative to their sex, i.e. they indicate that the adjustment period is more stressful for mothers than for fathers.El objetivo de la investigación es examinar las actitudes de los padres sobre el proceso de adaptación de los niños a la institución preescolar, y también las dificultades de separación que ocurren con el ingreso del niño en jardín de infantes. Los resultados del estudio proponen respuestas a las preguntas si los padres están familiarizados con los problemas que se manifiestan en el proceso de adaptación de los niños a la institución preescolar, y también preguntas sobre las posibilidades de su superación exitosa. El estudio involucró a 763 padres de niños en edad preescolar de Serbia. Se analizan las diferencias en las actitudes de los padres en relación con el género, el nivel de educación y la edad. En la investigación fue utilizada una escala de evaluación de Likert de cinco pasos, compuesta por 16 ítems agrupados en las siguientes categorías: factores que intervienen en el proceso de adaptación, indicadores de una adaptación exitosa y métodos para superar los problemas que surgen en el proceso de adaptación de los niños a la institución preescolar. Los padres lo consideran que la satisfacción de los niños cuando van al jardín de infantes representa un indicador muy importante de la finalización exitosa del proceso de adaptación en relación a la ausencia de llanto y resentimiento, y de que los padres, para superar las dificultades que ocurren cuando niños empiezan a ir en el jardín de infantes, a menudo se reúnen con maestros para familiarizarlos con los costumbres y las características de sus hijos, y luego hablan con sus hijos sobre los acontecimientos en el jardín de infancia. Los resultados del estudio indican que existen unas diferencias estadísticamente significativas en las actitudes de los padres con respecto al género, es decir, el período de adaptación es más estresante para las madres que para los padres

Radijalne zaptivače - uloga i značaj u održavanju mašina

Appropriate choice of sealing elements is one of essential tasks of sealing related with problem of working fluids loosening. In that way cost of maintenance are decreasing and reliability of machinery couples is improving. Radial sealers are used for sealing of different types of axles and shafts, primary in motor and vehicles industries as well as productions of machinery and equipment. This paper presents basical types of radial sealers with accent on material type used for their production, physical and chemical factors of material properties as well as some tribology characteristics. Influence of working conditions on strength of radial sealers is also shown as well as reliability on chemical reagents.Pravilan izbor zaptivnih elemenata kvalitetno rešava problem gubitka radnog fluida što je jedan od suštinskih zadataka zaptivanja. Na taj način smanjuju se troškovi održavanja a povećava pouzdanost mašinskih sklopova. Radijalne zaptivače se koriste za zaptivanje kod različitih osovina i vratila, prvenstveno u motornoj i vozilskoj industriji, mašinskoj industriji, industriji opreme. U radu su prikazane osnovne vrste radijalnih zaptivača, pri čemu je naglasak dat na vrste materijala koji se koriste za njihovu izradu, uticaj fizičko-hemijskih faktora na osobine materijala, kao i neke tribološke karakteristike. Takođe, prikazan je i uticaj radnih uslova na izdržljivost radijalnih zaptivača, kao i postojanost na hemijske reagense

Razmatranje potrošnje motornog ulja dizel motora

From aspect of regulation strict ecological regulations of exgsauts emissions from diesel engines as well imroving maintenace of diesel enigine, today reducing of consumption from motor lubricant is primary goal in construction of engine. In that way important role in that feature is researching in the level of consumption of oil and influencing factors. Date obtained in this field give consumers the costs of exploitation using adequate engine lubricant for certified engine. In this paper work it is evaluated problem of consumption of engine lubricant from several influencing parameters like construction of engine, condition of exploitation and quality parameters of measured lubricant.Sa aspekta zadovoljenja strogih ekoloških propisa izduvne emisije dizel motora kao i poboljšanja dizel motora sa stanovišta održavanja, danas smanjenje potrošnje motornog ulja predstavlja jedan od primarnih zadataka konstruktora motora. U tom kontekstu značajno mesto zauzima istraživanje nivoa potrošnje motornog ulja i uticajnih faktora. Rezultati istraživanja daju smernice i korisnicima koji mogu da projektuju troškove eksploatacije koji su ogledaju u korišćenju odgovarajućeg motornog ulja za odgovarajući motor. U radu je razmatran problem potrošnje motornog ulja sa stanovišta uticaja konstrukcije motora, uslova eksploatacije, kao i parametra kvaliteta motornog ulja

The effect of boron on the amount and type of carbides in chromium white irons

The effect of boron, in the amounts of 0.26, 0.39, and 0.59 wt.%, on the volume fraction and structure of carbides in Cr white irons was examined. It was demonstrated that the addition of boron can change the microstructural characteristics of white iron containing about 13 wt.% Cr. With increasing boron content, the volume fractions of M3C carbide increase., but the volume fracton of M7C3 carbide remains unchanged. The addition of boron tends to produce hard borides and/or borocarbides. It also prevents the formation of pearlite which results in alloys possessing good wear resistance

The effect of subchronic supplementation with folic acid on homocysteine induced seizures

Influence of folic acid on the CNS is still unclear. Folate has a neuroprotective effect, while on the other hand excess folate can exacerbate seizures in epileptics. The aim of the present study was to examine the effect of subchronic administration of folic acid on behavioural and electroencephalographic (EEG) characteristics of DL homocysteine thiolactone induced seizures in adult rats. The activity of Na+/K+-ATPase and Mg2+-ATPase in different brain regions was investigated. Adult male Wistar rats were divided into groups: 1. Controls (C, 0.9% NaCl); 2. DL homocysteine-thiolactone 8.0 mmol/kg (H); 3. Subchronic supplementation with folic acid 5 mg/kg for 7 days (F) and 4. Subchronic supplementation with F + single dose of H (FH). Seizure behaviour was assessed by incidence, latency, number and intensity of seizure episodes. Seizure severity was described by a descriptive scale with grades 0–4. For EEG recordings, three gold-plated recording electrodes were implanted into the skull. Subchronic supplementation with folic acid did not affect seizure incidence, median number of seizure episodes and severity in FH, comparison with H (p > 0.05). The majority of seizure episodes in all groups were of grade 2. There were no significant differences in lethal outcomes at 24 h upon H injection in the FH vs. H group. The activity of Na+/K+-ATPase and Mg2+-ATPase was significantly increased in almost all examined structures in the FH vs. H group. Subchronic folic acid administration did not exacerbate H induced seizures and completely recovered the activity of ATPases

The efficacy of hydrothermally obtained carbonated hydroxyapatite in healing alveolar bone defects in rats with or without corticosteroid treatment

Background/Aim. Autogenous bone grafting has been the gold standard in clinical cases when bone grafts are required for bone defects in dentistry. The study was undertaken to evaluate multilevel designed carbonated hydroxyapatite (CHA) obtained by hydrothermal method, as a bone substitute in healing bone defects with or without corticosteroid treatment in rats as assessed by histopathologic methods. Methods. Bone defects were created in the alveolar bone by teeth extraction in 12 rats. The animals were initially divided into two groups. The experimental group was pretreated with corticosteroids: methylprednisolone and dexamethasone, intramuscularly, while the control group was without therapy. Posterior teeth extraction had been performed after the corticosteroid therapy. The extraction defects were fulfilled with hydroxyapatite with bimodal particle sizes in the range of 50-250 mu m and the sample from postextocactional defect of the alveolar bone was analyzed pathohystologically. Results. The histopatological investigations confirmed the biologic properties of the applied material. The evident growth of new bone in the alveolar ridge was clearly noticed in both groups of rats. Carbonated HA obtained by hydrothermal method promoted bone formation in the preformed defects, confirming its efficacy for usage in bone defects. Complete resorption of the materials particles took place after 25 weeks. Conclusion. Hydroxyapatite completely meets the clinical requirements for a bone substitute material. Due to its microstructure, complete resorption took place during the observation period of the study. Corticosteroid treatment did not significantly affect new bone formation in the region of postextractional defects