N. Ljubijankić, Enis Šuta, Anela Ćatić, S. Begić, Sead Ljubijankić, Saida Ibragić
This work aimed to describe the synthesis and characterisation of two anionic Ru(III) complexes of the general formula Na[Ru - Cl 2 ( N -4-Cl-Ph-salim) 2 ] and Na[RuCl 2 ( N -3-Br-Ph-salim) 2 , their associated ligands, and determine their antioxidant activity. The ligands N- 4-Cl-phenylsalicylidenimine ( N -4-Cl-Ph-salimH, HL a ) and N- 3-Br-phenylsalicylidenimine ( N -3-Br-Ph-salimH, HL b ), Schiff bases, were synthesised from salicylaldehyde and chloroaniline or bromoaniline. The compounds were characterised us - ing IR spectroscopy and ESI ToF mass spectrometry. The following was confirmed: coordination of ligands on the Ru(III) centre, the molecular formulas, and the corresponding M − ions: [C 26 H 18 N 2 O 2 Cl 4 Ru] − ion, (m/z: 631.9173) and [C 26 H 18 N 2 O 2 Cl 2 Br 2 Ru] − ion, (m/z: 719.8283). The antioxidant activity was determined by the ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. In contrast to the ligands, both complexes proved to be strong scaven - gers of the ABTS and DPPH radicals with IC 50 (half maximal inhibitory concentration) values comparable to those of Trolox. As such, they present valuable candidates for further research related to their biological properties.
本工作旨在描述两种通式为Na[Ru-Cl2（N-4-Cl-Ph-salim）2]和Na[RuCl2（N-3-Br-Ph-salim2）的阴离子Ru（III）配合物及其相关配体的合成和表征，并测定其抗氧化活性以水杨醛和氯苯胺或溴苯胺为原料合成了席夫碱。用红外光谱和ESI-ToF质谱对化合物进行了表征。证实了配体在Ru（III）中心的配位，分子式，以及相应的M−离子：[C 26 H 18 N 2 O 2 Cl 4 Ru]−离子，（M/z:631.9173）和[C 26 H18 N 2 O2 Cl 2 Br 2 Ru]−阳离子，通过ABTS（2,2'-叠氮基双（3-乙基苯并噻唑啉-6-磺酸）和DPPH（1,1-二苯基-2-苦基肼基）测定其抗氧化活性。与配体相反，两种配合物都被证明是ABTS和DPPH自由基的强清除剂，IC50（最大抑制浓度的一半）值与Trolox相当。因此，它们为进一步研究其生物学特性提供了有价值的候选者。
{"title":"Ru(III) Complexes and Their Ligands Derived from Salicylaldehyde and Halogenated Anilines: Synthesis, Characterisation, and Antioxidant Activity","authors":"N. Ljubijankić, Enis Šuta, Anela Ćatić, S. Begić, Sead Ljubijankić, Saida Ibragić","doi":"10.15255/kui.2023.005","DOIUrl":"https://doi.org/10.15255/kui.2023.005","url":null,"abstract":"This work aimed to describe the synthesis and characterisation of two anionic Ru(III) complexes of the general formula Na[Ru - Cl 2 ( N -4-Cl-Ph-salim) 2 ] and Na[RuCl 2 ( N -3-Br-Ph-salim) 2 , their associated ligands, and determine their antioxidant activity. The ligands N- 4-Cl-phenylsalicylidenimine ( N -4-Cl-Ph-salimH, HL a ) and N- 3-Br-phenylsalicylidenimine ( N -3-Br-Ph-salimH, HL b ), Schiff bases, were synthesised from salicylaldehyde and chloroaniline or bromoaniline. The compounds were characterised us - ing IR spectroscopy and ESI ToF mass spectrometry. The following was confirmed: coordination of ligands on the Ru(III) centre, the molecular formulas, and the corresponding M − ions: [C 26 H 18 N 2 O 2 Cl 4 Ru] − ion, (m/z: 631.9173) and [C 26 H 18 N 2 O 2 Cl 2 Br 2 Ru] − ion, (m/z: 719.8283). The antioxidant activity was determined by the ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. In contrast to the ligands, both complexes proved to be strong scaven - gers of the ABTS and DPPH radicals with IC 50 (half maximal inhibitory concentration) values comparable to those of Trolox. As such, they present valuable candidates for further research related to their biological properties.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49485337","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}
M. M. Çakar, Marija Vuković Domanovac, Z. Findrik Blažević
Plastics are highly advanced materials that have a vast array of applications and are produced globally in an approximate amount of 350 to 400 million tons every year. Nevertheless, there are serious concerns about plastic waste and pollution as a result of the misuse and lack of control of their use in industries, including packaging, transportation, manufacturing, and agriculture. Approximately 1,000 years are required for plastic bags to decompose efficiently. Additionally, CO 2 and dioxins are released into the atmosphere by burning plastics, and they contribute to global warming. The Earth’s environment is over- whelmed with waste, mostly from poor recycling practices and low circular usage, resulting in millions of tons of waste generated annually. To combat this, new technologies for recycling post-consumer plastics are desperately needed to decrease plastic waste and improve the environment, while also finding ways to utilise these materials. Due to the inadequate disposal methods currently available for plastic waste, there has been increased interest in the use of microorganisms and enzymes designed for the biodegradation of non-degradable synthetic polymers via biocatalytic depolymerisation indicating that plastics treatment and recycling can be more efficient and sustainable.
{"title":"Discovery of Plastics-degrading Enzymes","authors":"M. M. Çakar, Marija Vuković Domanovac, Z. Findrik Blažević","doi":"10.15255/kui.2022.076","DOIUrl":"https://doi.org/10.15255/kui.2022.076","url":null,"abstract":"Plastics are highly advanced materials that have a vast array of applications and are produced globally in an approximate amount of 350 to 400 million tons every year. Nevertheless, there are serious concerns about plastic waste and pollution as a result of the misuse and lack of control of their use in industries, including packaging, transportation, manufacturing, and agriculture. Approximately 1,000 years are required for plastic bags to decompose efficiently. Additionally, CO 2 and dioxins are released into the atmosphere by burning plastics, and they contribute to global warming. The Earth’s environment is over- whelmed with waste, mostly from poor recycling practices and low circular usage, resulting in millions of tons of waste generated annually. To combat this, new technologies for recycling post-consumer plastics are desperately needed to decrease plastic waste and improve the environment, while also finding ways to utilise these materials. Due to the inadequate disposal methods currently available for plastic waste, there has been increased interest in the use of microorganisms and enzymes designed for the biodegradation of non-degradable synthetic polymers via biocatalytic depolymerisation indicating that plastics treatment and recycling can be more efficient and sustainable.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45259044","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}
M. Gojić, S. Kožuh, Ivana Ivanić, Robert Pezer, Ladislav Vrsalović, Tamara Holjevac Grgurić
This review presents part of scientific research in the development of shape memory alloys (SMA) based on copper at the Faculty of Metallurgy of the University of Zagreb in the period from 2006 to 2022, in cooperation with a number of universities and scientific institutions in the region. The following SMA alloys were studied: CuAlNi, CuAlMn, etc. Physical modelling, including nu - merical simulation of microstructure evolution and thermal analysis were performed. The SMA alloys were produced in arc, high-frequency, and induction furnaces by means of three different technologies: melt spinning, casting in metallic and/or graphite moulds, and continuous casting in bars. The selected SMA alloys were then hot and cold rolled. The heat treatment (quenching and tempering) and the characterisation of the functional properties of the SMA alloys under the different conditions were carried out. Numerous sophisticated methods were used to characterise the functional properties, in addition to testing the mechanical properties: optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), ener - gy dispersive spectroscopy (EDS), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), etc. According to several parameters (ductility, corrosion resistance, etc. ), it could be concluded that CuAlMn was the best alloy. As results of this investigation on SMA alloys, according to the CROSBI database (by December 23, 2022), the research team has published 33 articles in journals (including 23 articles in journals indexed in the Web of Science database), 74 papers in proceedings of international conferences, 18 abstracts in proceedings of conferences, and 5 other papers. In addition, 1 doctoral thesis, 12 bachelor theses, and 25 master theses were prepared and defended in the field of technical sciences in the areas of metallurgy and chemical engineering.
本文综述了萨格勒布大学冶金学院在2006年至2022年期间与该地区多所大学和科学机构合作开发基于铜的形状记忆合金(SMA)的部分科学研究。研究了以下几种SMA合金:CuAlNi、CuAlMn等。进行了物理模拟，包括微观结构演化的数值模拟和热分析。SMA合金是通过三种不同的技术在电弧炉、高频炉和感应炉中生产的:熔体纺丝、金属和/或石墨模具铸造和棒材连铸。然后对选定的SMA合金进行热轧和冷轧。对SMA合金在不同条件下的热处理(淬火和回火)和功能性能进行了表征。除了测试机械性能外，还使用了许多复杂的方法来表征功能特性:光学显微镜(OM)，扫描电子显微镜(SEM)，透射电子显微镜(TEM)，能量色散光谱(EDS)，动态力学分析(DMA)， x射线衍射(XRD)，电化学阻抗谱(EIS)等。根据几个参数(延展性、耐腐蚀性等)，可以得出CuAlMn是最好的合金。根据CROSBI数据库(截至2022年12月23日)，研究小组在期刊上发表了33篇论文(其中Web of Science数据库索引期刊23篇)，在国际会议论文集上发表了74篇论文，在会议论文集中发表了18篇摘要，并发表了5篇其他论文。在冶金、化工等技术科学领域，撰写并答辩博士论文1篇，学士论文12篇，硕士论文25篇。
{"title":"Razvoj legura s prisjetljivošću oblika na bazi bakra u okviru znanstveno-istraživačkih projekata na Metalurškom fakultetu Sveučilišta u Zagrebu","authors":"M. Gojić, S. Kožuh, Ivana Ivanić, Robert Pezer, Ladislav Vrsalović, Tamara Holjevac Grgurić","doi":"10.15255/kui.2023.003","DOIUrl":"https://doi.org/10.15255/kui.2023.003","url":null,"abstract":"This review presents part of scientific research in the development of shape memory alloys (SMA) based on copper at the Faculty of Metallurgy of the University of Zagreb in the period from 2006 to 2022, in cooperation with a number of universities and scientific institutions in the region. The following SMA alloys were studied: CuAlNi, CuAlMn, etc. Physical modelling, including nu - merical simulation of microstructure evolution and thermal analysis were performed. The SMA alloys were produced in arc, high-frequency, and induction furnaces by means of three different technologies: melt spinning, casting in metallic and/or graphite moulds, and continuous casting in bars. The selected SMA alloys were then hot and cold rolled. The heat treatment (quenching and tempering) and the characterisation of the functional properties of the SMA alloys under the different conditions were carried out. Numerous sophisticated methods were used to characterise the functional properties, in addition to testing the mechanical properties: optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), ener - gy dispersive spectroscopy (EDS), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), etc. According to several parameters (ductility, corrosion resistance, etc. ), it could be concluded that CuAlMn was the best alloy. As results of this investigation on SMA alloys, according to the CROSBI database (by December 23, 2022), the research team has published 33 articles in journals (including 23 articles in journals indexed in the Web of Science database), 74 papers in proceedings of international conferences, 18 abstracts in proceedings of conferences, and 5 other papers. In addition, 1 doctoral thesis, 12 bachelor theses, and 25 master theses were prepared and defended in the field of technical sciences in the areas of metallurgy and chemical engineering.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46684420","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}
Josipa Papac Zjačić, Magdalena Vujasinović, Marija Kovačić, A. Loncaric Bozic, H. Kušić, Z. Katančić, Z. Hrnjak-Murgić
The impact of plastic waste on the environment, human health, and ecosystems is one of the most important issues today. Once released into the environment, plastic waste is exposed to various stress factors that can lead to a reduction in its structural integrity and consequently to its fragmentation into smaller pieces. In this work, the effects of simulated UV aging on the surface properties and fragmentation of high-density polyethylene (HDPE) films were studied. HDPE films were prepared from pristine polymer granules
{"title":"From Macro to Micro Plastics; Influence of Photo-oxidative Degradation","authors":"Josipa Papac Zjačić, Magdalena Vujasinović, Marija Kovačić, A. Loncaric Bozic, H. Kušić, Z. Katančić, Z. Hrnjak-Murgić","doi":"10.15255/kui.2023.007","DOIUrl":"https://doi.org/10.15255/kui.2023.007","url":null,"abstract":"The impact of plastic waste on the environment, human health, and ecosystems is one of the most important issues today. Once released into the environment, plastic waste is exposed to various stress factors that can lead to a reduction in its structural integrity and consequently to its fragmentation into smaller pieces. In this work, the effects of simulated UV aging on the surface properties and fragmentation of high-density polyethylene (HDPE) films were studied. HDPE films were prepared from pristine polymer granules","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43323268","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}
The forward osmosis (FO) process is currently being studied more despite other energy-consuming processes. In addition, several works show the performance of FO membranes as its major challenges, the study of the rejection of different molecules, energy consumption, and modelling of different objectives related to this process. The main purpose of our study was to evaluate the impact of the FO membranes characteristics on the rejection of organic molecules (neutral) by modelling of the latter. However, the current work deals with the application of Support Vector Machines (SVM) for predicting the rejection of organic molecules (53) by the FO membranes. In addition, the SVM model was compared with two other models: Artificial Neural Network (ANN) and Multiple Linear Regression (MLR). The coefficient of correlation ( R ) for the testing data was applied to display the best SVM model. The SVM model generated with Radial Basis Function (RBF) as the kernel function showed the best R value equal to 0.8526. MLR and ANN models had R values of 0.7630 and 0.8723, respectively.
{"title":"Support Vector Machines for Evaluating the Impact of the Forward Osmosis Membrane Characteristics on the Rejection of the Organic Molecules","authors":"Fouad Kratbi, Y. Ammi, S. Hanini","doi":"10.15255/kui.2022.081","DOIUrl":"https://doi.org/10.15255/kui.2022.081","url":null,"abstract":"The forward osmosis (FO) process is currently being studied more despite other energy-consuming processes. In addition, several works show the performance of FO membranes as its major challenges, the study of the rejection of different molecules, energy consumption, and modelling of different objectives related to this process. The main purpose of our study was to evaluate the impact of the FO membranes characteristics on the rejection of organic molecules (neutral) by modelling of the latter. However, the current work deals with the application of Support Vector Machines (SVM) for predicting the rejection of organic molecules (53) by the FO membranes. In addition, the SVM model was compared with two other models: Artificial Neural Network (ANN) and Multiple Linear Regression (MLR). The coefficient of correlation ( R ) for the testing data was applied to display the best SVM model. The SVM model generated with Radial Basis Function (RBF) as the kernel function showed the best R value equal to 0.8526. MLR and ANN models had R values of 0.7630 and 0.8723, respectively.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48199457","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}
Zvezdana Veljin, Vedrana Špada, Jakov Batelić, Ivan Pentek
This paper presents the investigation of corrosion of 15Mo3 pipe in the steam heater system of the Plomin thermal power plant. Corrosion damage led to a rupture in the system as well as delays. Therefore it was necessary to determine the type and the cause of the corrosion. Corrosion is clas - sified according to three factors: the mechanism, the specificity of its occurrence, and the form of the corrosion attack. Power plants are explained with an emphasis on thermal power plants, along with an analysis of the sample and system in which the damage occurred. The results of the inves - tigation of corrosion products on the pipe and the rupture itself are presented. Chemical analysis, microscopic research with light and electron microscopy, hardness tests according to Vickers, and analysis with FT-IR spectroscopy were carried out. Erosion corrosion was proven to be the cause of the failure in a specific example.
{"title":"Analiza korozije nastale na cijevi čelika 15Mo3 iz grijača vodene pare u termoelektrani Plomin","authors":"Zvezdana Veljin, Vedrana Špada, Jakov Batelić, Ivan Pentek","doi":"10.15255/kui.2022.075","DOIUrl":"https://doi.org/10.15255/kui.2022.075","url":null,"abstract":"This paper presents the investigation of corrosion of 15Mo3 pipe in the steam heater system of the Plomin thermal power plant. Corrosion damage led to a rupture in the system as well as delays. Therefore it was necessary to determine the type and the cause of the corrosion. Corrosion is clas - sified according to three factors: the mechanism, the specificity of its occurrence, and the form of the corrosion attack. Power plants are explained with an emphasis on thermal power plants, along with an analysis of the sample and system in which the damage occurred. The results of the inves - tigation of corrosion products on the pipe and the rupture itself are presented. Chemical analysis, microscopic research with light and electron microscopy, hardness tests according to Vickers, and analysis with FT-IR spectroscopy were carried out. Erosion corrosion was proven to be the cause of the failure in a specific example.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42304280","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}
Ante Lončarić, Ana-Marija Gotal Skoko, Ivana Flanjak, A. Jozinović, J. Babić, I. Tomac, M. Mihaljević Žulj, G. Fruk, M. Skendrović Babojelić, B. Šarkanj, T. Kovač
The aim of this work was to investigate the influence of cold storage at 2 °C for 180 days on water content, total acids, reduc - ing and total sugar, antioxidant activity, polyphenol oxidase activity, and polyphenol profile of three Croatian traditional apple cultivars (‘Kanadska Reneta’, ‘Ilzer Rosenapfel’, ‘Wagener’). A significant variation in polyphenol profile of apple cultivars under investigation was noted. The most represented polyphenols in all apple cultivars were procyanidin B2 followed by chlorogenic acid, epigallocatechin, epicatechin, and phloridzin. After storage, the content of procyanidin B2 and chlorogenic acid was higher, while content of epigallocatechin after storage was lower in all investigated apple cultivars. Water content before storage ranged between 79.17 and 80.76 %, and after storage between 75.62 and 78.56 %. Total acids, polyphenol oxidase activity, and flavonoids had decreased during storage, while reducing and total sugar content was higher after storage. Moreover, after storage, cultivar ‘Kanadska Reneta’ had the highest antioxidant activity measured by both ABTS and DPPH methods, 1.65 and 0.70 mmol trolox kg −1 , respectively. A significant variation in polyphenol profile of apple cultivars under investigation was noted. The most represented polyphenols in all apple cultivars were procyanidin B2, followed by chlorogenic acid, epigallocat - echin, epicatechin, and phloridzin. After storage, the content of procyanidin B2 and chlorogenic acid was higher, while content of epigallocatechin after storage was lower in all investigated apple cultivars. Overall, it can be concluded that investigated apple cultivars, after storage, preserved most of the antioxidants and functional properties.
{"title":"Influence of Cold Storage on Quality of Croatian Traditional Apple Cultivars","authors":"Ante Lončarić, Ana-Marija Gotal Skoko, Ivana Flanjak, A. Jozinović, J. Babić, I. Tomac, M. Mihaljević Žulj, G. Fruk, M. Skendrović Babojelić, B. Šarkanj, T. Kovač","doi":"10.15255/kui.2022.073","DOIUrl":"https://doi.org/10.15255/kui.2022.073","url":null,"abstract":"The aim of this work was to investigate the influence of cold storage at 2 °C for 180 days on water content, total acids, reduc - ing and total sugar, antioxidant activity, polyphenol oxidase activity, and polyphenol profile of three Croatian traditional apple cultivars (‘Kanadska Reneta’, ‘Ilzer Rosenapfel’, ‘Wagener’). A significant variation in polyphenol profile of apple cultivars under investigation was noted. The most represented polyphenols in all apple cultivars were procyanidin B2 followed by chlorogenic acid, epigallocatechin, epicatechin, and phloridzin. After storage, the content of procyanidin B2 and chlorogenic acid was higher, while content of epigallocatechin after storage was lower in all investigated apple cultivars. Water content before storage ranged between 79.17 and 80.76 %, and after storage between 75.62 and 78.56 %. Total acids, polyphenol oxidase activity, and flavonoids had decreased during storage, while reducing and total sugar content was higher after storage. Moreover, after storage, cultivar ‘Kanadska Reneta’ had the highest antioxidant activity measured by both ABTS and DPPH methods, 1.65 and 0.70 mmol trolox kg −1 , respectively. A significant variation in polyphenol profile of apple cultivars under investigation was noted. The most represented polyphenols in all apple cultivars were procyanidin B2, followed by chlorogenic acid, epigallocat - echin, epicatechin, and phloridzin. After storage, the content of procyanidin B2 and chlorogenic acid was higher, while content of epigallocatechin after storage was lower in all investigated apple cultivars. Overall, it can be concluded that investigated apple cultivars, after storage, preserved most of the antioxidants and functional properties.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44984915","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}
The possibility of determining the concentration of heavy metal ions, i.e., Cu 2+ ions in an aqueous solution of CuSO 4 ∙ 5H 2 O, was tested by electrochemical means. For this purpose, polarisation curves were recorded on a Pt electrode in solutions of known (0.1, 0.5, 1.0, 2.5, 5.0, 7.5, 10.0, 50.0, and 100.0 mM) and unknown concentrations of Cu 2+ ions with the reading of the limiting diffusion current. Polarisation measurements were performed in the potential range from open circuit potential to −3.0 V with different potential scan rates (1, 5, 10, 20, and 50 mV s −1 ). By cathodic deposition on the Pt surface, a reddish-brown copper coating was deposited, the thickness of which increased as the concentration of Cu 2+ ions in the solution increased. Furthermore, the limiting diffusion current i d increased linearly with the increase in Cu 2+ ion concentration, c . The i d = f ( c ) plot was constructed and the unknown concentrations of Cu 2+ ions in three randomly prepared CuSO 4 ∙ 5H 2 O solutions were determined. Heavy metal ions from polluted waters (Cu 2+ ions) can be successfully removed by electrochemical means, and their concentration determined.
{"title":"Determination of Cu2+ Ions Concentration by Electrochemical Methods","authors":"S. Gudić, Nikolina Krišto","doi":"10.15255/kui.2022.061","DOIUrl":"https://doi.org/10.15255/kui.2022.061","url":null,"abstract":"The possibility of determining the concentration of heavy metal ions, i.e., Cu 2+ ions in an aqueous solution of CuSO 4 ∙ 5H 2 O, was tested by electrochemical means. For this purpose, polarisation curves were recorded on a Pt electrode in solutions of known (0.1, 0.5, 1.0, 2.5, 5.0, 7.5, 10.0, 50.0, and 100.0 mM) and unknown concentrations of Cu 2+ ions with the reading of the limiting diffusion current. Polarisation measurements were performed in the potential range from open circuit potential to −3.0 V with different potential scan rates (1, 5, 10, 20, and 50 mV s −1 ). By cathodic deposition on the Pt surface, a reddish-brown copper coating was deposited, the thickness of which increased as the concentration of Cu 2+ ions in the solution increased. Furthermore, the limiting diffusion current i d increased linearly with the increase in Cu 2+ ion concentration, c . The i d = f ( c ) plot was constructed and the unknown concentrations of Cu 2+ ions in three randomly prepared CuSO 4 ∙ 5H 2 O solutions were determined. Heavy metal ions from polluted waters (Cu 2+ ions) can be successfully removed by electrochemical means, and their concentration determined.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41701824","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}
Silk fibroin (SF), a unique and promising natural material extracted from silkworm, has gained much attention for its use as biomedical material, because of its biocompatibility, biodegradability, and nontoxicity. Despite its strength, SF alone is not appropriate because of its poor flexibility. Thermoplastic polyurethane (TPU) is a very desirable material for medical applications because of its flexibility. A solution to the problem of SF’s poor flexibility can be achieved by mixing flexible TPU with SF. The aim of this work was to examine the influence of FS content on the physical and thermal properties of TPU/FS blends. Blends of SF and TPU were prepared with melt mixing of TPU with 5, 10, 15, and 20 wt% of SF in a laboratory Brabender kneading chamber. The speci - mens of the neat components and their blends were moulded in a hydraulic press. The structural characteristics, thermal, and viscoelastic properties of neat TPU, SF and their blends (TPU/SF blends) were examined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The FTIR results showed that the SF was successfully introduced to TPU matrix. Results obtained with DSC and DMA measurements showed that, when the SF content increased in the TPU/SF blends, the T g , expressed as T eig , T mg , and T efg of the TPU, slightly shifted to lower temperature due to the incorporation of the amorphous phase of FS (aspartic acid) in the amorphous phase of TPU, and mobility of polymer chains increased. The melting temperature ( T m ), expressed as T eim , T pm , and T efm , decreased because of the less organised crystal structure with the addition of SF. Thermal stability was determined by TGA, which showed that, with the addition of SF, the thermal stability decreased because of the lower thermal stability of SF.
{"title":"Priprema i karakterizacija mješavina na osnovi termoplastičnog poliuretana i fibroina svile","authors":"E. Govorčin Bajsić, Mario Meheš, Lukša Benić","doi":"10.15255/kui.2022.069","DOIUrl":"https://doi.org/10.15255/kui.2022.069","url":null,"abstract":"Silk fibroin (SF), a unique and promising natural material extracted from silkworm, has gained much attention for its use as biomedical material, because of its biocompatibility, biodegradability, and nontoxicity. Despite its strength, SF alone is not appropriate because of its poor flexibility. Thermoplastic polyurethane (TPU) is a very desirable material for medical applications because of its flexibility. A solution to the problem of SF’s poor flexibility can be achieved by mixing flexible TPU with SF. The aim of this work was to examine the influence of FS content on the physical and thermal properties of TPU/FS blends. Blends of SF and TPU were prepared with melt mixing of TPU with 5, 10, 15, and 20 wt% of SF in a laboratory Brabender kneading chamber. The speci - mens of the neat components and their blends were moulded in a hydraulic press. The structural characteristics, thermal, and viscoelastic properties of neat TPU, SF and their blends (TPU/SF blends) were examined by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The FTIR results showed that the SF was successfully introduced to TPU matrix. Results obtained with DSC and DMA measurements showed that, when the SF content increased in the TPU/SF blends, the T g , expressed as T eig , T mg , and T efg of the TPU, slightly shifted to lower temperature due to the incorporation of the amorphous phase of FS (aspartic acid) in the amorphous phase of TPU, and mobility of polymer chains increased. The melting temperature ( T m ), expressed as T eim , T pm , and T efm , decreased because of the less organised crystal structure with the addition of SF. Thermal stability was determined by TGA, which showed that, with the addition of SF, the thermal stability decreased because of the lower thermal stability of SF.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49162866","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}
Electrochemical sensors have the ability to convert the electrochemical reaction that occurs be-tween the analyte and the electrode into a useful signal. Potentiometric sensors, ion-selective electrodes, an important member of the electrochemical sensor family, have been the focus of much research for almost a century. Their constant development and combination with the development of other scientific and technological fields have given them a wide range of applications. Properties of ion-selective electrodes, such as simplicity of method, low cost, small sensor size, fast response, and reliability, have made them valuable competitors of other methods for determining the concentration of analytes in different real samples with minimal or no pretreatment of the samples. Considering the wide distribution and great importance of iron(III) cations in the human body and environment, there is a great need to develop analytical tools for their rapid and effi - cient determination. This paper, presents different literature sources dealing with the development of potentiometric sensors for the determination of iron(III) cations, focusing on scientific papers published in the last decade. The active centre of the sensor, its linear dynamic range, the limit of detection, and the change in potential depending on the change in analyte concentration are shown. It has been found that Fe 3+ cations can be determined successfully in numerous real samples, such as pharmaceutical preparations, biological samples, different water samples (drinking, waste, mineral...), food products such as green and black tea, etc. Thanks to the wide linear range, low detection limits, and a wide range of real samples in which they can be applied, ion-selective electrodes are promising candidates for replacing some more sophisticated methods for the determination of iron(III) cations.
{"title":"Potenciometrijski senzori za određivanje željezovih(III) kationa","authors":"Andrea Paut, Ante Prkić, Ivana Mitar, Lucija Guć","doi":"10.15255/kui.2022.074","DOIUrl":"https://doi.org/10.15255/kui.2022.074","url":null,"abstract":"Electrochemical sensors have the ability to convert the electrochemical reaction that occurs be-tween the analyte and the electrode into a useful signal. Potentiometric sensors, ion-selective electrodes, an important member of the electrochemical sensor family, have been the focus of much research for almost a century. Their constant development and combination with the development of other scientific and technological fields have given them a wide range of applications. Properties of ion-selective electrodes, such as simplicity of method, low cost, small sensor size, fast response, and reliability, have made them valuable competitors of other methods for determining the concentration of analytes in different real samples with minimal or no pretreatment of the samples. Considering the wide distribution and great importance of iron(III) cations in the human body and environment, there is a great need to develop analytical tools for their rapid and effi - cient determination. This paper, presents different literature sources dealing with the development of potentiometric sensors for the determination of iron(III) cations, focusing on scientific papers published in the last decade. The active centre of the sensor, its linear dynamic range, the limit of detection, and the change in potential depending on the change in analyte concentration are shown. It has been found that Fe 3+ cations can be determined successfully in numerous real samples, such as pharmaceutical preparations, biological samples, different water samples (drinking, waste, mineral...), food products such as green and black tea, etc. Thanks to the wide linear range, low detection limits, and a wide range of real samples in which they can be applied, ion-selective electrodes are promising candidates for replacing some more sophisticated methods for the determination of iron(III) cations.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46469418","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}
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