Contemporary Materials最新文献

{"title":"FLOCCULATION STUDY OF NATURAL QUARTZ SAMPLE USING ANIONIC POLYACRYLAMIDE","authors":"Ljiljana Tankosić, S. Sredić, P. Tančić, Z. Nedić","doi":"10.7251/comen2002112s","DOIUrl":"https://doi.org/10.7251/comen2002112s","url":null,"abstract":"The waste sludge generated during processing of iron ore in the Omarska mine (The Republic of Srpska, Bosnia and Herzegovina) is fine-grained (15μm), containing relatively high concentrations of iron, and quartz as its major impurity. The flocculation behaviour of the primary natural raw “quartz” sample from Omarska mine was studied in the present paper. This sample is composed of major quartz which dominates over minor contents of clay minerals and feldspars, and contain 92.9% of SiO2. Particle size distribution analysis confirm that it is present as fine and ultra-fine particles. The zeta potential of quartz depends on pH value. Settling experiments were performed by using three different dispersants (Na-hexamethaphosphate, Na-pyrophosphate and Na-silicate), and anionic polyacrylamide as flocculants. The best results were achieved with Nahexametaphosphate (1000 g/t) and anionic polyacrylamide A 100. The effect of a flocculant on the settling rate depends on solid concentration. Settling rates increase significantly with the increase of the liquid component in both cases (natural settling and hindered settling by addition of a flocculant).","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82279815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IMPACT OF CREATINE MONOHYDRATE ON BODY MASS OF SWIMMERS","authors":"Goran Grahovac, Bojan Guzina, Milomir Trivun, Goran Pašić","doi":"10.7251/comen2002169g","DOIUrl":"https://doi.org/10.7251/comen2002169g","url":null,"abstract":"The subject of the research is impact of creatine monohydrate on a mass of swimmers. The test was performed on a sample of 60 swimmers among members of the Academic Swimming Club „22. April“ divided into two groups aged between 21 and 25. All respondents are male and in good health. The respondents belonging to this population are at the zenith of morphological and motor development and are well motivated to advance in swimming. The measurement was carried out at the end of May and half of June 2008 at the premises of the Recreation Center Srpske Toplice (water temperature 28°C). The respondents were measured for body mass at baseline and after 21 days of taking creatine. The main objective of the paper is to determine whether taking creatine for three weeks shows significant differences in a mass gain of swimmers. The results of the research show that the differences in body mass between the two measurements have statistical significance.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86423202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"STUDY OF THE BIOLOGICAL ACTIVITY DESCRIPTORS OF THE BARBITURIC ACID DERIVATIVES","authors":"S. Apostolov, Đ. Vaštag, Borko M. Matijević, Gorana S. Mrđan, Jelena Nakomčić","doi":"10.7251/comen2002077a","DOIUrl":"https://doi.org/10.7251/comen2002077a","url":null,"abstract":"Barbituric acid derivatives have been pharmacologically significant compounds for decades. The central nervous system effects are conditioned by the presence of the pyrimidine-trione ring and the nature of the substituent in position 5. Lipophilicity as one of the key molecular descriptors of biological activity for selected barbituric acid derivatives was determined experimentally, using reversed-phase thin layer chromatography (RP TLC18 F254s), in two solvent systems. The influence of the substituent’s nature and the effects of applied organic modifiers on the chromatographic behavior of the tested derivatives were examined. For the studied derivatives the values of the partition coefficient (logP) as a standard measure of lipophilicity and effective concentration (EC50) as a measure of acute toxicity for different test organisms were calculated applying the appropriate software packages. Dependence between the chromatographic parameters as assumed measures of lipophilicity and the software-derived biological activity parameters of the studied barbituric acid derivatives were studied by linear regression analysis.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87758736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"STUDY OF IRON OXIDE NANOPARTICLES DOPED WITH COPPER: ANTIMICROBAL AND PHOTOCATALYTICAL ACTIVITY","authors":"A. Šmitran, Dijana Jelić, Sanja Pržulj, Savka Vračević, D. Gajić, Mladena Malinović, L. Božić","doi":"10.7251/comen2002093j","DOIUrl":"https://doi.org/10.7251/comen2002093j","url":null,"abstract":"Last decade is designated as the postantibiotic era due to increasing number of resistant and multiresistant strains of microorganisms, which developed resistance to one or more antibiotics. Antimicrobial resistance becomes a global health problem. This phenomenon of antimicrobial resistance will undoubtedly affect the efficiency and use of antibiotics in the future. Science and technological development are committed to researching and developing new antibiotics that will satisfy the missing criteria and address the problem of antimicrobial resistance. One of the possible solutions lies in nanotechnologies. Nanoparticles have been isolated as one of the most promising substances on which microorganisms rarely or even develop mechanisms of resistance. The nanoparticles may be in conjunction with already existing antibiotics structures and contribute to the improvement of physicochemical properties in order to successfully overcome the mechanism of antimicrobial resistance. By designing nanoparticles with proper physicochemical and biochemical characteristics we determine their application. The aim of this research is to dope synthesized iron oxide nanoparticles with copper ions in order to test their antimicrobial activity and to evaluate their use as potential antimicrobial agent. Extracts of green tea and ascorbic acid were used as reduction agent for the iron oxide nanoparticles doped with Cu. The antimicrobial activity of the synthesized nanoparticles on the isolates Acinetobacter baumannii and methicillin resistant Staphylococcus aureus (MRSA) was performed by the agar well diffusion method. Synthesized iron oxide nanoparticles showed activity against Acinetobacter baumannii with inhibition zone around 12 mm. Photocatalytical activity was also evaluated by UV/VIS spectrophotometry. Samples doped with copper showed much better photocatalytical performances.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"289 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75637629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PROPERTIES OF THE HAND MIXED PMMA BASED CEMENT FOR BIOMEDICAL APPLICATIONS","authors":"F. Živić, N. Grujovic, S. Pelemiš, D. Adamović","doi":"10.7251/comen2002085z","DOIUrl":"https://doi.org/10.7251/comen2002085z","url":null,"abstract":"This paper presents insights into the recent trends in development of PMMA bone cements considering their improvements for applications in clinical practice. Experimental investigation of hand mixed PMMA bone cement was realized, aiming to determine mechanical behavior of the material during nanoindentation. Standard multi-cycle indentation tests were applied, with maximum load of 15 N and immediate load relaxation down to 5 N, with sharp Vickers indenter. Indentation curves were obtained and analyzed as the function of the normal load vs penetration depth, for three different numbers of cycles (100, 200 and 300 cycles) and different indentation positions on the sample surface. Resulting indents were analyses from the aspect of the final material structure and its subsequent mechanical behavior. Agglomeration of PMMA beads was observed in the final hardened cement in some surface zones, thus indicating non-homogenous material structure. Changes in the number of cycles did not show significant influence on the mechanical response of the sample. However, sites with agglomerated PMMA beads showed significantly different indentation curves, thus indicating that hand-mixing of PMMA bone cement can produce non-homogenous final material structure.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91073050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NANOTECHNOLOGY IN THE FUNCTION OF SUSTAINABLE WATER USE","authors":"S. Stevović, Ž. Nestorović, N. Đurić","doi":"10.7251/comen2002102s","DOIUrl":"https://doi.org/10.7251/comen2002102s","url":null,"abstract":"Nanotechnology, as contemporary field of research in forming of materials and devices on the level of molecule and atoms, is founding broad utilization in different scientific and engineering domains. The influence of nanotechnology on the development of contemporary human society has got a significant potential in domains as economy, environment protection, health and improvement of the quality of life. The need for fresh water as a necessary resource for living world, as well as the economic activity on the level of humanity is growing in the conditions of increasing population, increasing economic activities and increasing pollution. In that sense the conventional methods for water treatment may become ineffective for providing sustainable utilization of water resources in the future. Nanotechnology as a contemporary scientific and engineering field is considered efficient and potentially, the only solution for sustainable utilization of fresh water in the future. The efforts in nanotechnology utilization for sustainability of fresh water resources mean comprehensive approach and clarity in defining goals as well as the ways for their realization. The basic expectations of nanotechnology in the sense of fresh water resources utilization are directed to enhancement of fresh water availability, increase of efficiency of fresh water delivery and enabling next generation systems for fresh water quality monitoring. The increase of fresh water availability by nanotechnology means development of filtering systems and development of membrane systems, inverse osmosis for water desalinization and catalysts for water treatment. Efficiency of fresh water delivery based on nanotechnology means reducing energy necessary for its transportation, developing system of pipes and components which are easier, stronger and which will last longer as well as to provide cheap materials which improve energy efficiency for heating and cooling. All these processes for nanotechnology development aiming to provide sustainable fresh water resources utilization require significant efforts on scientific and engineering level in order to be utilized in everyday life. This paper aims to research the state of the art of nanotechnology development in the domain of sustainable utilization of fresh water resources.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78908417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EVALUATION OF FLOOR COVERINGS FROM THE ECOLOGICAL AND ECONOMIC ASPECT IN THE DESIGN STAGE","authors":"Marina Nikolić Topalović, M. Stanković","doi":"10.7251/comen2002150n","DOIUrl":"https://doi.org/10.7251/comen2002150n","url":null,"abstract":"Measures to reduce the impact of the construction sector on the environment and human health need to be taken at the design stage of the facility and evaluate building materials and products from an ecological and economic aspect. For the research needs, a comparison of floor coverings at the design stage was made to assess their impact during the life cycle. The research uses the life cycle analysis (LCA), a methodology that is the basis for analyzing the impacts during the life cycle of the analyzed construction products. The research covers the life cycle stages from A1 to C4, according to the standard ISO EN 15978: 2011. The software package BEES, the National Institute of Standardization and Technology (NIST), the United States of America is used for the turn. Five types of floor coverings were analyzed, from the aspect of their impact on the environment and human health, but also from the economic point of view. The research has shown that in the design phase, using software packages can be managed with the quality of the environment, and the project design, and hence the quality of the facility. The research also points to the need for a national software package that can analyze construction products and materials. Their application would improve the national construction industry and favored materials that are environmentally and economically acceptable in relation to materials with unfavorable effects on the environment and human health.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74598279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BIOMEDICAL POTENTIAL OF SELECTED MUSHROOM SPECIES","authors":"T. Stanojković, M. Kosanić","doi":"10.7251/comen2002162k","DOIUrl":"https://doi.org/10.7251/comen2002162k","url":null,"abstract":"The aim of this study was to determine neuroprotective, antioxidant, antimicrobial and cytotoxic potential of acetone extracts of Coprinus comatus and Coprinopsis picacea mushrooms. The neuroprotetive activity was tested against acetylcholinesterase enzyme using the Ellman method. Antioxidant activity was evaluated by free radical scavenging ability, superoxide anion radical scavenging activity and reducing power. The total phenol content was examined using Folin-Ciocalteu reagent. The antimicrobial potential was determined by a microdilution method against 12 microorganisms. The cytotoxic activity was tested using MTT method on the Hela, A549 and LS174 cells. Our results indicate that C. comatus expressed a stronger neuroprotective effect (the percentage of inhibition of acetylcholinesterase was within the range 19.66-51.73%) than C. picacea. In antioxidant effect C. comatus had more potent free radical scavenging activity (IC50 = 276.69 μg/mL) and superoxide anion radical scavenging activity (IC50 = 39.40 μg/mL), while reducing power was relatively similar for both species. The total amount of phenols for C. comatus and C. picacea was 50.57 and 50.20 μg PE/mg of dry extracts, respectively. In antimicrobial activity, C. picacea showed a better effect with MIC values from 0.1 to 7.5 mg/mL. Finally, C. picacea expressed stronger cytotoxicity toward A549 and LS174 cells, while C. comatus was more active against Hela cell.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"142 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80166500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RESONANCE AS NEW METHOD IN DETERMINING THE AGE OF PAINTS","authors":"V. Zorić","doi":"10.7251/comen2002135z","DOIUrl":"https://doi.org/10.7251/comen2002135z","url":null,"abstract":"In this work the mechanism of resonance is proposed as the way for determining of paint age, by application of this method. This method consists in accelerated paint ageing on the basis of resonance. Measuring is concerned with humidity of paint and it is a general method since water molecules are present in every material. The molecules of water have random distribution. They oscillate in shallow potential wells so that they can be ejected from paint with low energy quanta, thus decreasing the paint humidity by evaporation process. The high energy quanta accelerate this process of the paint ageing. Since water molecule is mechanical oscillator it can be turned into resonance by application of mechanical periodical field, but since it is electric dipole it can be even more conveniently turned into resonance with periodic electric field.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79190125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ANTIMICROBIAL AND PHOTOCATALYTIC PROPERTIES OF DOPED AND UNDOPED ZINC OXIDE NANOPARTICLES","authors":"Savka Vračević, A. Šmitran, Sanja Pržulj, D. Gajić, Mladena Malinović, L. Božić, Dijana Jelić","doi":"10.7251/comen2002128v","DOIUrl":"https://doi.org/10.7251/comen2002128v","url":null,"abstract":"In this paper, zinc oxide nanoparticles doped with copper (ZnO/CuNP) were synthesized by using black and green tea, vitamin C and trisodium citrate as a reduction agent. Antimicrobial and photocatalytic properties were tested. The antimicrobial activity of the doped synthesized ZnO NP against the clinical isolates of Acinetobacter baumannii and methicillin resistant Staphylococcus aureus (MRSA) was performed by the agar well diffusion method. ZnO NP with all four reduction agents showed good antimicrobial efficiency against both microorganisms, with similar inhibition zone. Photocatalytic activity was more pronounced in case of undoped, pure ZnO nanoparticles, while the best results for doped ZnO samples were obtained for ZnO/Cu NPs using black tea.","PeriodicalId":10617,"journal":{"name":"Contemporary Materials","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83710591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}