Dynamic response of existing embankment dams in specific geotechnical and seismological conditions: contemporary framework for Serbian national guidelines

We suggest a new approach for evaluating the dynamic response of existing embankment dams as a guideline for national engineering regulations in Serbia. This novel concept is applied to the case study of the existing embankment dam “Zavoj” (Serbia), built at the place of the previously formed natural dam (due to large landslide activity), and exposed to Mw7.4 Vrančea earthquake and under double impact of Kresna earthquake (Mw6.8 and Mw7.1). Results of transient FEM and direct dynamical analysis of the three-dimensional FEM model of the “Zavoj” dam indicate that the existing dam is stable in dynamic conditions, while the surrounding terrain is either on the verge of stability or becomes unstable, depending on the assumed geotechnical conditions and a relevant earthquake analyzed. As a result, we construct a landslide hazard map in dynamic conditions and the dam damage map, which enables the identification of unstable, damaged, or weak parts of the dam, its immediate surroundings, and the accumulation zone in general. The results indicate that direct dynamical analysis is obligatory when two succeeding earthquakes occur and temporal evolution of displacements in the model is required. Additionally, the application of the remaining bearing capacity criterion indicates a much larger zone of potential instability compared to the extent of equivalent plastic strain and the location of the old sliding surface. By following the proposed guidelines, one secures the inclusion of all the relevant influential factors in the comprehensive dynamic analysis of existing embankment dams, leading eventually to reliable decisions on further design, (re)construction, and/or monitoring activities

Reheating of zinc-titanate sintered specimens

The scope of this work was observing dimensional and heat transfer changes in ZnTiO3 samples during heating in nitrogen and air atmosphere. Interactions of bulk specimens with gaseous surrounding induce microstructure changes during heating. Sintered ZnTiO3 nanopowder samples were submitted to subsequent heating. Dilatation curves and thermogravimetric with simultaneous differential thermal analysis TGA/DTA curves were recorded. Reheating was performed in air and nitrogen atmospheres. Reheated samples obtained at different characteristic temperatures in air were analyzed by X-ray diffraction (XRD). Microstructures obtained by scanning electron microscopy (SEM) of reheated sintered samples are presented and compared. Reheating in a different atmosphere induced different microstructures. The goal was indicating possible causes leading to the microstructure changes. © 2015 International Institute for the Science of Sintering (IISS). All rights reserved

In situ XRPD and DSC study of order-disorder phase transition in nanosize Li-ferrite

An order-disorder phase transition of nanosize Li-ferrite (Li0.50Fe2.50O4) was studied by DSC measurements and in situ XRPD technique. The phase transition temperature is found to be 762 °C (DSC) and (745±5) °C (XRPD).Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Povezanost tipa preloma kosti i stepena formiranja kalusa sa koncentracijom leptina kod dece sa prelomima dugih kostiju

Background/Aim. Recent studies indicate that adipokines have an important role in bone physiology and pathology. Recent data indicate that adipokine leptin functions as a regulator of bone growth at multiple levels, systemically and locally. So far, it has been shown that leptin influences bone volume and bone mineral density in a population with metabolic and/or hormonal abnormality. Data concerning leptin values in non-obese children with fractures are scarce. Methods. This study included 93 non-obese children with long bone fractures (LBF), 14 children with short bone fractures (SBF), and 19 healthy children. Leptin concentration was determined in two blood samples (day 0 and day 21) and analyzed according to gender, fracture type, anatomical localization of the fracture, fracture topography, callus formation, and the healing outcome. Results. Children with LBF demonstrated significantly increased leptin levels compared to the control group (both day 0/day 21). In the control group, girls had significantly more leptin than boys. Leptin value was significantly influenced by anatomical localization since boys and girls with humerus fracture and girls with femur fracture had the highest average leptin concentration in the initial sample. Boys with incomplete callus formation had the highest leptin concentration (both day 0/day 21), significantly elevated compared to boys' samples in the control group, boys' samples with an intermediary and well-formed callus, and also increased compared to the initial samples of girls with incomplete callus. Better callus formation in girls was associated with an increment of leptin concentrations in the second over the initial sample. Girls with partially and satisfactorily formed callus had significantly increased leptin concentration in the second sample (day 21) compared to the boys' group. Conclusion. Leptin concentration was significantly increased (both samples) in children with LBF compared to children with SBF and corresponding controls. Leptin concentration was highly influenced by gender. High blood leptin concentrations in boys or low leptin concentrations in girls immediately upon fracture could be used to identify groups of children with incomplete callus formation.Uvod/Cilj.Novijestudije pokazuju da adipokini imaju važnu ulogu u fiziologiji i patologiji kostiju. Takođe, najnoviji podaci pokazuju da adipokin leptin funkcioniše kao regulator rasta kostiju sistemski i lokalno. Pokazano je da leptin utiče na volumen kostiju i mineralnu gustinu kostiju u populaciji sa metaboličkom i/ili hormonskom abnormalnošću. Podaci o vrednostima leptina kod negojazne dece sa frakturama su oskudni. Metode. U ovu studijubil a su uključena93 negojazna deteta sa prelomima dugih kostiju (LBF), 14 dece sa prelomima malih kostiju (SBF) i 19 zdrave dece. Koncentracija leptina određena je u 2 uzorka krvi (0. danai 21 . dana) i analizirana prema polu, tipu frakture, lokalizaciji anatomske frakture, topografiji frakture, formiranju kalusa i ishodu zarastanja.Rezultati.Deca sa LBF imala su značajnopovećane nivoeleptina u poređenju sa kontrolnom grupom u oba uzorka krvi ( 0. dana/21 . dana). U kontrolnoj grupi devojčice su imale značajno više nivoe leptina od dečaka. Na vrednost leptina značajno je uticala anatomska lokalizacija, jer su dečaci i devojčice sa prelomom humerusa i devojčice sa prelomom femura imali najveću prosečnu koncentraciju leptina u početnom uzorku. Dečaci sa nepotpuno for miranim kalusom imali su najveću koncentraciju leptina (u oba uzorka, 0. dana/21. dana),značajno višuu odnosu na kontrolne uzorke dečaka, uzorke dečaka s intermedijarnim i dobro formiranim kalusom, a takođe višu u odnosu na koncentracije leptina u početnim uzorcima djevojčica s nepotpunim kalusom. Bolje formiranje kalusa kod devojčica je bilo povezano sa poveć anjem koncentracije leptina u drugom (21. dan) u odnosu na početni uzorak(0. dan). Devojčice sa delimično i zadovoljavajuće formiranim kalusom imale su značajno višu koncentraciju leptina u drugom uzorku (21. dan ) u odnosu na grupu dečaka. Zaključak. Koncentracija leptina je značajno povećana (u oba uzorkakrvi ) kod dece sa LBF u poređenju sa decom sa SBF i odgovarajućim kontrolama. Koncentracija leptina je zavisna od pola. Visok nivo leptina u krvi kod dečaka ili niska koncentracija leptina kod devojčica odmah nakon preloma može se koristiti za identifikaciju grupa dece sa nepotpunim formiranjem kalusa

Ergonomics problems in dental profession-dentists working position

Background/Aim: Dental professionals are under higher risk of development musculoskeletal disorders. Working in unnatural position is one of the main risk factor for the development of MSDs. The aim of study was to record inclinations of the back in dentists during typically dental work. Material and Methods: In order to monitor the inclination of the body, high-performance sensor systems, triaxial digital 12-bit accelerometers LIS3LV02 (SGS-Thomson Microelectronics, USA) were installed. The inclination of the body was measured in ten dentists, while performing dental work. Results: During dental work in a sitting position, sloping back more than 20 ̊ was during 74% of the time, while during standing 62% of the time. The participants performed the dental examination sloping to the left side. During sitting, the inclination to the left side was greater than 20 ̊ during 65% of the time, while during work in the standing position it was 50%. Conclusions: An inclination of the back, more than 20 degrees is state as one of the main risk factor for the development of MSD. Inclination of the dentist's body in antero-posterior and medio-lateral direction during daily work in standing as well in sitting position was greater than 20 degrees. According to those facts dentists are under risk of developing musculoskeletal diseases during their daily working procedure. According to that ergonomics in dentistry is an area of research that needs more attention. The implementation of ergonomic principles in usual dental work leads to increased work performance, greater satisfaction, efficiency and productivit

Characterization of films based on cellulose acetate/poly(caprolactone diol) intended for active packaging prepared by green chemistry principles

Biodegradable active packaging films based on a cellulose acetate and poly(caprolactone diol) blend with incorporated lemongrass oil were developed. Films were prepared using a novel bio-based plasticizer, glycerol tritartarate, synthesized using the principles of green chemistry. The influence of the plasticizer, as well as the essential oil amount, on the structural, surface, mechanical, and thermal properties of the blend was investigated. The plasticizer was shown to work as a compatibilizer for two polymers, according to the results of scanning electron microscopy and surface energy analysis. Blends with a greater amount of plasticizer possessed better mechanical properties but showed worse resistance to water. The antimicrobial property of the blend with lemongrass oil was found to be superior to that of the blend without essential oil. The incorporation of lemongrass oil into the polymer blend resulted in one more step longer thermal degradation process. The optimal film properties, biodegradability, cost-effective preparation method, and additional functions made these films suitable for the production of packaging for grapefruit.This peer-reviewed accepted version of the article will be available in open access on 15 July 2023. The published article available at the publisher [https://pubs.acs.org/doi/10.1021/acssuschemeng.2c02009

Dielectric Properties of Nanosized ZnFe2O4

In this paper we present the results concerning the dielectric properties of the nanosized ZnFe2O4. Dielectric permittivity, the loss factor, as well as the conductivity, were measured in the temperature range 300-630 K and at 1 Hz, 10 Hz, 100 Hz, 1 kHz and 10 kHz frequencies. Signifi cant improvements in permittivity, loss factor and ionic conductivity comparing to bulk samples have been observed

Nanosize ferrites obtained by ball milling: Crystal structure, cation distribution, size-strain analysis and Raman investigations

Spinels samples Fe2.85Y0.15O4 (S1) and Fe2.55In0.45O4 (S2), such as Fe3O4 + gamma-Fe2O3 (S3) were obtained by ball milling. TEM micrograph as well as XRPD line broadening analyses show nanosize nature of the ferrite powders. Cation distribution, found by Rietveld refinement of the site occupancies, indicate Y3+ ions presence at 16d sites in Fe2.85Y0.15O4, and a random In3+ ions distribution on both 8a and 16d sites in Fe2.55In0.45O4 (space group Fd (3) over barm). From the XRPD line broadening analysis crystallite size and strain values were determined. The crystallite size and strain anisotropy is significant, especially for Fe2.85Y0.15O4 and Fe2.55In0.45O4. This result is discussed regarding the influence of the cation substitutions. The Raman signature confirms the spinel structure and the homogeneity of the particles. (c) 2006 Elsevier SAS. All rights reserved