Influence of a Low Content of PEO Segment on the Thermal, Surface and Morphological Properties of Triblock and Diblock PCL Copolymers

Marijana Ponjavic,Marija S. Nikolic,Sanja Jevtic,Jelena Rogan,Sanja Stevanovic,Jasna Djonlagic 한국고분자학회 2016 Macromolecular Research Vol.24 No.4

Two series, one of triblock (PCL/PEO/PCL) and the other of diblock (PCL/PEO) copolymers were prepared by ring-opening polymerization of ε-caprolactone catalized with tin(II) octoate and by using dihydroxy or monohydroxy poly(ethylene oxide) as the macroinitiator. The PEO block length was fixed (Mn 1,000 g/mol) and the PCL block lengths (Mn 10,000-40,000 g/mol) were tailored by changing weight ratio of ε-CL/PEO. The copolymers’ structure was confirmed by 1H and quantitative 13C NMR spectroscopy while their molecular weights were determined by GPC analysis. The thermal properties and the degree of crystallinity of the copolymers were investigated and compared by using DSC and WAXS. Both types of copolymers were semicrystalline with the orthorhombic PCL crystal lattice. The surface morphology of the copolymer films was investigated by using optical microscopy and AFM analysis, which confirmed the spherulitic lamellar structure with spherulites of different diameters. Data indicated that a low content of PEO segment had an influence on thermal degradation behavior, crystallinity and morphology of copolymers. Roughness of copolymer films was affected by the content of PEO and correlated with the spherulites’ diameter. The small changes in water and moisture absorption properties of copolymers compared to homopolymer PCL were observed.

Antioxidant and Antimicrobial Properties of Some Lichens and Their Constituents

Marijana Kosanic,Branislav Rankovic' 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.12

The aim of this study is to examine the in vitro antioxidant and antimicrobial activities of the acetone,methanol, and aqueous extracts of the lichens Cladonia furcata (many-forked Cladonia), Hypogymnia physodes (puffed lichen), and Umbilicaria polyphylla (manyleaf navel lichen) and the antimicrobial activity of fumarprotocetraric acid, gyrophoric acid, and physodic acid isolated from the respective lichen species. Antioxidant activity was evaluated by five different methods: free radical scavenging, superoxide anion radical scavenging, reducing power, determination of total phenolic compounds, and determination of total flavonoid content. U. polyphyla exhibited more powerful antioxidant activities than the other lichen species examined: methanol extracts of U. polyphyla showed 90.08% free radical scavenging activities (the ratio was greater than those of standard antioxidants). Moreover, the extracts tested had effective reducing power and superoxide anion radical scavenging. Total contents of phenol and flavonoid in extracts were determined as pyrocatechol equivalents and as rutin equivalents, respectively. A significant strong relationship between total phenolic and flavonoid contents and their antioxidative activities was observed. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration by the broth microdilution method against six species of bacteria and 10 species of fungi. In general, the lichen extracts tested and their respective acids had relatively strong antimicrobial activity against the microorganisms tested. The present study shows that the lichen species tested demonstrated strong antioxidant and antimicrobial activities. The results suggest that lichens may be used as good sources of natural antioxidants and for pharmaceutical purposes in treating various diseases.

Microstructural and mechanical characteristics of self-compacting concrete with waste rubber

Marijana Hadzima-Nyarko,Karlo E. Nyarko,Daniela Djikanovic,Goran Brankovic 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.2

Due to the increasing environmental pollution caused by scrap tires, a solution is being sought to recycle and use them in a field of civil engineering, i.e., construction. This paper will provide a brief overview of previous researches that give detailed information on the advantages and disadvantages, considering the microstructural and mechanical characteristics of self-compacting concrete, when waste tire rubber as an aggregate is added. With this aim, a database of 144 different mixtures of self-compacting concrete with partial substitute of natural aggregate with recycled tire rubber (self-compacting rubberized concrete, SCRC) provided by various researchers was created. In this study we show that Gaussian process regression (GPR) modelling is an appropriate method for predicting compressive strength of SCC with recycled tire rubber particles and is in accordance with the results displayed by SEM images.

Establishing non-linear convective heat transfer coefficient

Cuculic, Marijana,Malic, Neira Toric,Kozar, Ivica,Tibljas, Aleksandra Deluka Techno-Press 2022 Coupled systems mechanics Vol.11 No.2

The aim of the work presented in this paper is development of numerical model for prediction of temperature distribution in pavement according to the measured meteorological parameters, with introduction of non-linear heat transfer coefficient which is a function of temerature difference between the air and the pavement. Developed model calculates heat radiated from the pavement back in the air, which is an important part of the heat trasfer process in the open air surfaces. Temperature of the pavement surface, heat radiation together with many meteorological parameters were measured in series during two years in order to validate the model and calibrate model parameters. Special finite element method for temperature heat transfer towards the soil together with the time integration scheme are used to solve the governing equation. It is proved that non-linear heat transfer coefficient, which is a function of time and temperature difference between the air and the pavement, is required to decribe this phenomena. Proposed model includes heat tranfer coefficient callibration for specific climate region, through the iterative inverse procedure.

Estimation of fundamental period of reinforced concrete shear wall buildings using self organization feature map

Mehdi Nikoo,Marijana Hadzima-Nyarko,Faezehossadat Khademi,Sassan Mohasseb 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.2

The Self-Organization Feature Map as an unsupervised network is very widely used these days in engineering science. The applied network in this paper is the Self Organization Feature Map with constant weights which includes Kohonen Network. In this research, Reinforced Concrete Shear Wall buildings with different stories and heights are analyzed and a database consisting of measured fundamental periods and characteristics of 78 RC SW buildings is created. The input parameters of these buildings include number of stories, height, length, width, whereas the output parameter is the fundamental period. In addition, using Genetic Algorithm, the structure of the Self-Organization Feature Map algorithm is optimized with respect to the numbers of layers, numbers of nodes in hidden layers, type of transfer function and learning. Evaluation of the SOFM model was performed by comparing the obtained values to the measured values and values calculated by expressions given in building codes. Results show that the Self-Organization Feature Map, which is optimized by using Genetic Algorithm, has a higher capacity, flexibility and accuracy in predicting the fundamental period.

WhitenoneCoat Hypertension: the Neglected Subgroup in Hypertension

Cesare Cuspidi,Marijana Tadic,Giuseppe Mancia,Guido Grassi 대한심장학회 2018 Korean Circulation Journal Vol.48 No.7

The clinical prognostic importance of white coat hypertension (WCH), that is, the clinical condition characterized by an increase of office but a normal ambulatory or home blood pressure (BP) is since a long time matter of considerable debate. WCH accounts for a consistent portion of hypertensive patients (up to 30–40%), particularly when hypertension is mild or age is more advanced. Although scanty and inconsistent information is available on the response of office and out-office BP to antihypertensive treatment and the cardiovascular (CV) protection provided by treatment, an increasing body of evidence focusing on the association of WCH with CV risk factors, subclinical cardiac and extra-cardiac organ damage and, more importantly, with CV events indicates that the risk entailed by this condition is intermediate between true normotension and sustained hypertension. This review will address a number of issues concerning WCH with particular attention to prevalence and clinical correlates, relation with subclinical target organ damage and CV morbidity/mortality, therapeutic perspectives. Several topics covered in this review are based on data acquired over the past 20 years by the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study, a longitudinal survey performed by our group on the general population living in the surroundings of Milan area in the north part of Italy.

A comparative study on the seismic provisions of different codes for RC buildings

Huseyin Bilgin,Marijana Hadzima-Nyarko,Ercan Işık,Hayri Baytan Ozmen,Ehsan Harirchian 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.2

Significant structural damages due to earthquakes reveal the importance of seismic design provisions. This paper presents a comparison between the seismic design provisions of Albania, Croatia, Iran, and Turkey for the design of mid-rise reinforced-concrete (RC) frames. Information on the historical development of the considered provisions are given. The code provisions are compared, illustrating the main differences in the minimum requirements for column and beam detailing and analysis for mid-rise RC frames. 4-story, 5-story, and 6-story buildings are designed according to each design code, and their performance is evaluated comparatively by using a displacement-based adaptive pushover procedure and eigenvalue analysis. It is observed that recent Turkish code has the highest and Albanian code has the lowest level of requirements in terms of member size and reinforcement detailing. The considered models indicate 15%, 20% and 50%, lower period values than the Croatia, Iran and Albania buildings, respectively. Additionally, building models per Croatia, Iran and Albania codes have 30%, 35% and 65% less base shear capacity when compared to Turkish building codes. Building models per Croatia and Iran codes indicate similar properties both in terms of strength and stiffness.

Parameters of Calcium Metabolism Fluctuated during Initiation or Changing of Antipsychotic Drugs

Dragan R. Milovanovic,Marijana Stanojevic Pirkovic,Snezana Zivancevic Simonovic,Milovan Matovic,Slavica Djukic Dejanovic,Slobodan M. Jankovic,Dragan Ravanic,Milan Petronijevic,Dragana Ignjatovic Risti 대한신경정신의학회 2016 PSYCHIATRY INVESTIGATION Vol.13 No.1

ObjectiveaaSerum parameters of calcium homeostasis were measured based on previously published evidence linking osteoporotic fractures and/or bone/mineral loss with antipsychotics. MethodsaaProspective, four-week, time-series trial was conducted and study population consisted of patients of both genders, aged 35-85 years, admitted within the routine practice, with acute psychotic symptoms, to whom an antipsychotic drug was either introduced or substituted. Serial measurements of serum calcium, phosphorous, magnesium, 25(OH)D, parathyroid hormone, calcitonin, osteocalcin and C-telopeptide were made from patient venous blood samples. ResultsaaCalcium serum concentrations significantly decreased from baseline to the fourth week (2.42±0.12 vs. 2.33±0.16 mmol/L, p=0.022, n=25). The mean of all calcemia changes from the baseline was -2.6±5.7% (-24.1 to 7.7) with more decreases than increases (78 vs. 49, p=0.010) and more patents having negative sum of calcemia changes from baseline (n=28) than positive ones (n=10) (p=0.004). There were simultaneous falls of calcium and magnesium from baseline (63/15 vs. 23/26, p<0.001; OR=4.75, 95% CI 2.14–10.51), phosphorous (45/33 vs. 9/40, p<0.001; 6.06, 2.59–14.20) and 25(OH)D concentrations (57/21 vs. 13/35, p<0.001; 7.31, 3.25–16.42), respectively. Calcemia positively correlated with magnesemia, phosphatemia and 25(OH)D values. Parathyroid hormone and C-telopeptide showed only subtle oscillations of their absolute concentrations or changes from baseline; calcitonin and osteocalcin did not change. Adjustment of final calcemia trend (depletion/accumulation) for relevant risk factors, generally, did not change the results. ConclusionaaIn patients with psychotic disorders and several risks for bone metabolism disturbances antipsychotic treatment was associated with the decrease of calcemia and changes in levels of the associated ions.

Neuroticism and pain catastrophizing aggravate response to pain in healthy adults: an experimental study

( Adriana Banozic ),( Ana Miljkovic ),( Marijana Bras ),( Livia Puljak ),( Ivana Kolcic ),( Caroline Hayward ),( Ozren Polasek ) 대한통증학회 2018 The Korean Journal of Pain Vol.31 No.1

Background: The aim of this study was to investigate the association between neuroticism, pain catastrophizing, and experimentally induced pain threshold and pain tolerance in a healthy adult sample from two regions of the country of Croatia: the island of Korcula and city of Split. Methods: A total of 1,322 participants were enrolled from the Island of Korcula (n = 824) and the city of Split (n = 498). Participants completed a self-reported personality measure Eysenck Personality Questionnaire (EPQ) and pain catastrophizing questionnaire Pain Catastrophizing Scale (PCS), followed by a mechanical pain pressure threshold and tolerance test. We have explored the mediating role of catastrophizing in the relationship between neuroticism and pain intensity. Results: The results showed that pain catastrophizing partially mediated the relationship between neuroticism and pain intensity, suggesting the importance of pain catastrophizing in increasing vulnerability to pain. The results also indicated gender-related differences, marked by the higher pain threshold and tolerance in men. Conclusions: This study adds to the understanding of the complex interplay between personality and pain, by providing a better understanding of such mechanisms in healthy adults. (Korean J Pain 2018; 31: 16-26)

Experimental evaluation of the performance of self-compacting concrete contains nano clay and nano egg shell

Hilal, Nahla N.,Hadzima-Nyarko, Marijana Techno-Press 2022 Advances in concrete construction Vol.13 No.5

The rising prices of landfills and the lack of cement production are motivating researchers to be more interested in using wastes to produce concrete mixtures materials. The use of waste materials such as eggshell and matakoline waste not only reduces landfill costs and space, but also reduces the cost of cement production for the concrete mixture. However, recycling waste materials has become critical in order to effectively manage environmental sustainability. The purpose of this paper is to investigate the appropriate properties of self-compacting concrete (SCC) by incorporating waste materials such as crushed ceramics as coarse aggregate and nano egg shell (NES) and nanoclay (NC) as cement replacements. Fresh properties of SCC, such as segregation, flow time and diameter, V-funnel, H2/H1 ratio, and fresh unit weight of concrete mixtures, as well as hardened properties, such as 7, 14, and 28 days compressive strength and 28 and 90 days flexural strength, were measured for this purpose. The presence of NC in the SCC mixture enhanced the compressive strength of the concrete when 5% of NES was added or in the case without the addition of NES compared to the control mixture. The flexural strength enhanced with the incorporation of NC in the SCC increased the flexural strength of the concrete compared to the control mixture, but the incorporation of 5% of NES decreased the flexural strength compared to the mixtures with NC. These results prove the possibility of using crushed ceramics as the coarse aggregate, and NES and NC as substitutes for 5, 7, and 10% of the cement in SCC, because the properties of such SCC in hardened and fresh states are satisfactory.