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Search Results: 1 - 10 of 225511 matches for " Savi? Aleksandar R. "
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Investigation of cement based composites made with recycled rubber aggregate
Jevti? Dragica Lj.,Zaki? Dimitrije M.,SaviAleksandar R.
Hemijska Industrija , 2012, DOI: 10.2298/hemind111203010j
Abstract: The results of experimental investigations performed on cement based composites made with addition of recycled rubber as a partial replacement of natural river aggregate are presented in this paper. Different properties of cement based mortar were analyzed, both in fresh and in hardened state. Tested properties in the fresh state included: density, consistency and volume of entrained air. In the hardened state, the following properties were tested: density, mechanical properties (compressive and flexural strength), modulus of elasticity, adhesion to concrete substrate, water absorption, freeze-thaw resistance and ultrasonic pulse velocity. The obtained results indicate that recycled rubber can be successfully applied as a partial replacement of natural river aggregate in cement based composites, in accordance with the sustainable development concept. The investigation showed that physical-mechanical properties of cementituous composites depend to a great extent on the percentage of replacement of natural river aggregate with recycled rubber, especially when the density, strength, adhesion and freeze-thaw resistance are concerned. The best results were obtained in the freeze-thaw resistance of such composites.
Munchausen syndrome by proxy
Jovanovi? Aleksandar A.,Popovi? Vesna R.,Savi? Slobodan,Alempijevi? ?or?e M.
Srpski Arhiv za Celokupno Lekarstvo , 2005, DOI: 10.2298/sarh0504173j
Abstract: This review deals with bibliography on Munchausen syndrome by proxy (MSbP). The name of this disorder was introduced by English psychiatrist Roy Meadow who pointed to diagnostic difficulties as well as to serious medical and legal connotations of MSbP. MSbP was classified in DSM-IV among criteria sets provided for further study as "factitious disorder by proxy", while in ICD-10, though not explicitly cited, MSbP might be classified as "factitious disorders" F68.1. MSbP is a special form of abuse where the perpetrator induces somatic or mental symptoms of illness in the victim under his/her care and then persistently presents the victims for medical examinations and care. The victim is usually a preschool child and the perpetrator is the child's mother. Motivation for such pathological behavior of perpetrator is considered to be unconscious need to assume sick role by proxy while external incentives such as economic gain are absent. Conceptualization of MSbP development is still in the domain of psychodynamic speculation, its course is chronic and the prognosis is poor considering lack of consistent, efficient and specific treatment. The authors also present the case report of thirty-three year-old mother who had been abusing her nine year-old son both emotionally and physically over the last several years forcing him to, together with her, report to the police, medical and educational institutions that he had been the victim of rape, poisoning and beating by various individuals, especially teaching and medical staff. Mother manifested psychosis and her child presented with impaired cognitive development, emotional problems and conduct disorder.
Fluctuating vs. Continuous Exposure to H2O2: The Effects on Mitochondrial Membrane Potential, Intracellular Calcium, and NF-κB in Astroglia
Aleksandar Baji?, Mihajlo Spasi?, Pavle R. Andjus, Danijela Savi, Ana Parabucki, Aleksandra Nikoli?-Koki?, Ivan Spasojevi?
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076383
Abstract: The effects of H2O2 are widely studied in cell cultures and other in vitro systems. However, such investigations are performed with the assumption that H2O2 concentration is constant, which may not properly reflect in vivo settings, particularly in redox-turbulent microenvironments such as mitochondria. Here we introduced and tested a novel concept of fluctuating oxidative stress. We treated C6 astroglial cells and primary astrocytes with H2O2, using three regimes of exposure – continuous, as well as fluctuating at low or high rate, and evaluated mitochondrial membrane potential and other parameters of mitochondrial activity – respiration, reducing capacity, and superoxide production, as well as intracellular ATP, intracellular calcium, and NF-κB activation. When compared to continuous exposure, fluctuating H2O2 induced a pronounced hyperpolarization in mitochondria, whereas the activity of electron transport chain appears not to be significantly affected. H2O2 provoked a decrease of ATP level and an increase of intracellular calcium concentration, independently of the regime of treatment. However, fluctuating H2O2 induced a specific pattern of large-amplitude fluctuations of calcium concentration. An impact on NF-κB activation was observed for high rate fluctuations, whereas continuous and low rate fluctuating oxidative stress did not provoke significant effects. Presented results outline the (patho)physiological relevance of redox fluctuations.
Solving the two-dimensional packing problem with m-M calculus
SaviAleksandar,?ukilovi? Tijana,Filipovi? Vladimir
Yugoslav Journal of Operations Research , 2011, DOI: 10.2298/yjor1101093s
Abstract: This paper considers the two dimensional rectangular packing problem. The mathematical formulation is based on the optimization of a non-linear function with piecewise linear constraints with a small number of real variables. The presented method of m-M calculus finds all optimal solutions on small instances. Computational performance is good on smaller instances.
Modeling of properties of fiber reinforced cement composites
Jevti? Dragica,Zaki? Dimitrije,SaviAleksandar
Facta Universitatis Series : Architecture and Civil Engineering , 2008, DOI: 10.2298/fuace0802165j
Abstract: This paper presents the results of authors' laboratory testing of the influence of steel fibers as fiber reinforcement on the change of properties of cement composite mortar and concrete type materials. Mixtures adopted - compositions of mortars had identical amounts of components: cement, sand and silica fume. The second type of mortar contained 60 kg/m3 of fiber reinforcement, as well as the addition of the latest generation of superplasticizer. Physical and mechanical properties of fiber reinforced mortars and etalon mixtures (density, flexural strength, compressive strength) were compared. Tests on concrete type cement composites included: density, mechanical strengths and the deformation properties. The tests showed an improvement in the properties of fiber reinforced composites.
Current diagnosis and treatment of the osteoarticular tuberculosis
Le?i? Aleksandar,Bumba?irevi? Marko,Savi? Branislava,?obelji? Goran
Srpski Arhiv za Celokupno Lekarstvo , 2004, DOI: 10.2298/sarh0410345l
Abstract: In 1993, tuberculosis was recognized as global medical problem by WHO. Recurring flare-up of this disease was triggered by difficult socioeconomic situation of the countries in transition, current development of immunocompromising diseases, and some other factors have contributed, too. The osteoarticular tuberculosis has been always postprimary and localized form of the disease, which, due to certain similarity to some other osteoarticular diseases, has been challenge for orthopaedic surgeons both from diagnostic and treatment aspects. Bacteriological diagnostics has had a limited value due to application of recommended tuberculostatic medication before obtaining specimens from bones or joints; and, on the other hand, rapid bacteriological methods, because of their expensive equipment, could be carried out in large mycobacteriology laboratories only. New visualizing methods, CT and MRI, have been particularly important for detection and monitoring of tuberculosis process in the spine during the early stage of the disease, what is impossible to achieve with native radiograms. Programmed administration of tubercuiostatic drugs both in non-operative and surgical treatment has been proven necessary.
Tooth macromorphological and ultrastructural analysis of osteological material from the medieval locality of St. Panteleimon Church in Ni
Miti? Nadica,Miti? Aleksandar,Miti? Vladimir,Savi? Vojin
Srpski Arhiv za Celokupno Lekarstvo , 2010, DOI: 10.2298/sarh1012699m
Abstract: Introduction. Analysis of macromorphological and ultrastructural tooth characteristics of osteological material from the medieval site of St. Pantaleimon Church in Ni provides us with insight on the life, nutrition and habits of medieval population, as well as the structure and composition of their teeth. Objective. The aim of this research, based on the tooth inspection of skeletal remains from the medieval site of St. Pantaleimon Church in Ni , was to analyze macromorphological characteristics , ultrastructure of the dental tissue of maxillary and mandibular molars, canines and incisors, as well as their chemical composition. Methods. Macromorphological and ultrastructural analysis of the dental tissue of osteological material dating from the 12th century included 1312 teeth with advanced abrasion. Macromorphological changes were detected by using a dental mirror, probe and radiography. After irrigation, the teeth were prepared using the standard procedure and analyzed by scanning electronic microscopy (JEOL-JSM-5300). Chemical analysis was done by expanded downscaling (EDS) method for Mg, P, Ca. Results. The analysis detected second degree abrasions of all teeth in individuals aged 20-25 years. Third and fourth degree abrasions of teeth were detected in individuals aged over 40 years. Ultrastructural analysis showed a complete obliteration of dentin tubules and pulp of the lower incisors, the apposition of intratubular dentin inside the tubules, as well as extensive deformity and loss of dentin structure on molars with preserved pulp volume and nerve fiber calcification. The calcification of nerve fibers showed that the formation of intratubular dentin was proportional with the biological potential of pulp and the degree of abrasion, and inversely proportional with the size of dentin surface. Chemical analysis showed that in the analyzed teeth Ca composition was slightly lower than that in the control group, P composition was almost identical, while Mg composition was multiply increased in comparison to the control group consisting of today’s persons of matching age and examined teeth as the medieval individuals. Conclusion. Different ultrastructural tooth characteristics as a part of the complex masticatory system of the medieval man are the result of individual and the whole community adaptation to actual living conditions. Nerve fibers calcification of the pulp can explain the absence of pain despite the high level of dental abrasion.
Influence of the secondary electron emission on the characteristics of radio frequency plasmas
Bojarov Aleksandar,Radmilovi?-Ra?enovi? Marija,Savi? Marija
Hemijska Industrija , 2011, DOI: 10.2298/hemind100810063b
Abstract: In this paper the influence of secondary emission on the characteristics of RF plasmas has been studied. An asymmetrical dual-frequency capacitively coupled plasma reactor has been modeled with one dimensional PIC/MCC (Particle in Cell with Implemented Monte Carlo Collisions) code. The main feature of the modeling code represents the realistic model of the ion-induced secondary electron emission. Secondary emission of electrons is one of the important processes that effects the characteristics of rf plasmas. For modeling the secondary yield per ion, we have used equations proposed by Phelps and Petrovi (Plasma Sources Sci. Technol. 8 (1999) R21-R44) for differently treated metal surfaces. In the model, the energy dependence of the yields per ion for differently treated metal surfaces has been implemented. Results are compared for yields for the so called “dirty” and “clean” surfaces, and the spatial profiles of charged particles and ion energy distributions were observed. The simulation results indicate that the plasma characteristics are greatly affected by the ion-induced secondary emission, changing the overall parameters of dual-frequency capacitively coupled plasma reactors especially in applications as etching devices. Conclusion is that an exact model of the secondary electron emission should be included, as to ensure better agreement between simulation and experiment.
Meniscus transplantation in the rabbit knee joint using a deep frozen meniscus allograft-pathohistologi- cal picture
Le?i? Aleksandar,Savi? V.,Krsti? Nikola,Bumba?irevi? Marko
Acta Veterinaria , 2002, DOI: 10.2298/avb0204249l
Abstract: The aim of the study was to assess the clinical, radiological and histological characteristics of deep frozen meniscal allograft for the rabbit knee. Eighteen (18) New Zealand white rabbits were operated on both knees and evaluated at three time intervals: after 2 weeks (first group), 8 weeks (second group) and 36 weeks (third group). Left knees without meniscal transplantation, served as the controls. Meniscal grafts obtained from other rabbits were stored in a deep freeze at -17 °C when required deep frozen menisci were thawed in sterile saline and transplanted in the place of the removed right medial meniscus of the experimental animal. The general condition, operated knees and X-ray pictures were monitored. After sacrifice the meniscal allografts were histologically analyzed. There were no adverse clinical and radiological pathological findings after transplantation, while in the control group changes were noted. At histological evaluation, 2 weeks after transplantation the collagen fibers were not oriented and there was a low cell population. Vascularity was observed in the second group, with cell repopulation and young immature collagen fibers. In the third group at 36 weeks the collagen tissue was more mature, with significant cell repopulation. We may conclude that deep frozen meniscal allografts show significant collagen remodeling and cellular repopulation. New menisci protect the underlying cartilage. Thus this procedure appears beneficial in cases where there is no possibility to reconstruct the meniscal lesion.
Revision anterior cruciate ligament reconstruction due to knee instability
Milankov Miroslav,Mili?i? Aleksandar,Savi? Dragan,Stankovi? Milan
Medicinski Pregled , 2007, DOI: 10.2298/mpns0712587m
Abstract: Introduction. The primary goal of anterior cruciate ligament reconstruction is to provide stability to the knee and regain full range of motion. Although great improvement has been achieved in surgical techniques and rehabilitation, some patients are not completely satisfied with the results of surgery and a revision anterior cruciate ligament reconstruction is necessary. Material and Methods. Revision arthroscopic anterior cruciate ligament reconstruction was carried out in eleven patients with bone-tendon-bone autografts. The surgery was performed in a standard manner and the graft was taken from the opposite knee. Eight men and three women were evaluated. The mean age of patients was 26 (17-34) years. Repeated instability of the knee was caused by injury in five patients, while six patients were unsatisfied with the position of the graft. Results. The follow up was 4,2 years (2-8) respectively. The mean Lysholm and Gillquist score after operation was 88 (65-90). Preoperative and postoperative tibial shift was 9mm (6-15) and 2mm (0-4), respectively. The preoperative pivot shift test was grade 2 and 3 in all patients. Postoperative pivot shift test was negative in seven patients, in three it was grade 1 and grade 2 in one patient. According to the IKDC scale, preoperative results were abnormal in three patients and in eight they were severely abnormal. Postoperative IKDC score was normal in five patients, in four nearly normal, and in one patient the score was still abnormal. Five patients continued to be active in sports activities, four patients decreased the level of sports activity and two stopped all sports activities. Conclusion. Success of revision anterior cruciate ligament reconstruction requires detailed preoperative evaluation of the repeated instability of the knee. The treatment plan is then decided upon. The patients must be preoperatively informed about the real possibilities of revision surgery. Only a mutual collaboration between the patient, physiatrist and a surgeon is a key for successful treatment and return to previous level of sports activities.
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