Compared to cobalt-chromium and stainless steel based alloys, titanium and titanium based al - loys have found wide application in biomedicine, and are used as biomedical implants due to their excellent properties, but are yet to be widely used due to the high cost of their production. Their most important properties include: excellent biocompatibility, good mechanical properties, osseointegration, and corrosion resistance. In addition to presenting some commonly used bio - medical materials, this article gives an overview of the development of titanium biomaterials and their biomedical applications. Biomaterials are widely used in biomedicine to repair, replace or regenerate body tissue. Given that an increasing number of failed implantations caused by path - ogenic bacterial infection are known, among the functions that could be added to biomaterials is antibacterial action, which is of great importance. Recently, antibacterial metal alloys have shown great potential as a new type of biomedical material .
{"title":"Biomaterijali na bazi titana","authors":"Magdalena Jajčinović, Ljerka Slokar Benić","doi":"10.15255/kui.2023.006","DOIUrl":"https://doi.org/10.15255/kui.2023.006","url":null,"abstract":"Compared to cobalt-chromium and stainless steel based alloys, titanium and titanium based al - loys have found wide application in biomedicine, and are used as biomedical implants due to their excellent properties, but are yet to be widely used due to the high cost of their production. Their most important properties include: excellent biocompatibility, good mechanical properties, osseointegration, and corrosion resistance. In addition to presenting some commonly used bio - medical materials, this article gives an overview of the development of titanium biomaterials and their biomedical applications. Biomaterials are widely used in biomedicine to repair, replace or regenerate body tissue. Given that an increasing number of failed implantations caused by path - ogenic bacterial infection are known, among the functions that could be added to biomaterials is antibacterial action, which is of great importance. Recently, antibacterial metal alloys have shown great potential as a new type of biomedical material .","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41791179","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}
Josip Sacher, Marko Sejdić, Matea Gavran, N. Bolf, Željka Ujević Andrijić
The aim of this work was to create a computer program that can be used to calculate the optimal cooling temperature profile of the batch crystalliser. Potassium nitrate dissolved in water was used as a model system for process research. To create a mathematical model of the process, population balances were used, i.e. , their moment transformation. To obtain the optimal temperature profile, a discretisation of the temperature profile was performed using a global optimisation algorithm. A genetic algorithm was used for the optimisation, while a system of ordinary differential equations was solved using the Runge-Kutta 4,5 method. The objective function was to minimise the ratio between the third moment of crystals produced by secondary nucleation, and the third moment of seed crystals at the end of the process. Firstly, the influence of the stopping conditions of the genetic algorithm on the computation time and the value of the objective function was tested. After the optimal stopping condition was determined, the influence of the number of discreti- sation points of the temperature profile on the value of the objective function and the required computation time was investigated. It was found that the optimal stopping condition was when fifteen members of a generation had objective function values that did not differ by more than the tolerance. It is shown that the optimal solution was achieved by dividing the temperature profile into eight parts. To check the repeatability of the calculation for optimal conditions, the calculation was repeated nine times. The optimal temperature profile was compared to a linear cooling of the same duration to determine the benefits of optimisation. The results of the simulation experiments indicate a significant improvement in the process when using the optimal temperature profile compared to the linear profile.
{"title":"Proračun optimalnog temperaturnog profila hlađenja šaržnog kristalizatora","authors":"Josip Sacher, Marko Sejdić, Matea Gavran, N. Bolf, Željka Ujević Andrijić","doi":"10.15255/kui.2023.001","DOIUrl":"https://doi.org/10.15255/kui.2023.001","url":null,"abstract":"The aim of this work was to create a computer program that can be used to calculate the optimal cooling temperature profile of the batch crystalliser. Potassium nitrate dissolved in water was used as a model system for process research. To create a mathematical model of the process, population balances were used, i.e. , their moment transformation. To obtain the optimal temperature profile, a discretisation of the temperature profile was performed using a global optimisation algorithm. A genetic algorithm was used for the optimisation, while a system of ordinary differential equations was solved using the Runge-Kutta 4,5 method. The objective function was to minimise the ratio between the third moment of crystals produced by secondary nucleation, and the third moment of seed crystals at the end of the process. Firstly, the influence of the stopping conditions of the genetic algorithm on the computation time and the value of the objective function was tested. After the optimal stopping condition was determined, the influence of the number of discreti- sation points of the temperature profile on the value of the objective function and the required computation time was investigated. It was found that the optimal stopping condition was when fifteen members of a generation had objective function values that did not differ by more than the tolerance. It is shown that the optimal solution was achieved by dividing the temperature profile into eight parts. To check the repeatability of the calculation for optimal conditions, the calculation was repeated nine times. The optimal temperature profile was compared to a linear cooling of the same duration to determine the benefits of optimisation. The results of the simulation experiments indicate a significant improvement in the process when using the optimal temperature profile compared to the linear profile.","PeriodicalId":43849,"journal":{"name":"Kemija u Industriji-Journal of Chemists and Chemical Engineers","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41244126","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}
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":null,"pages":null},"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}
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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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}
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":null,"pages":null},"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}
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":null,"pages":null},"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}
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":null,"pages":null},"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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