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Protective cotton with sustainable chitosan/lignin nanocoating and Ag nanoparticles
No full textMultifunctional effects are crucial for manufacturing of higher value-added textiles in both technical textile and apparel industries. Low antimicrobial activity and absence of UV protection limit the production of cotton out-door and protective garments. In an attempt to develop a simple and efficient route for the fabrication of antimicrobial and UV-protective cotton fabrics, layer-by-layer deposition of biopolymer chitosan and magnesium lignosulfonate, followed by in situ synthesis of Ag nanoparticles (NPs) using sodium borohydride as a reducing agent, was performed. The effect of the number of bilayers (4 and 12) and initial concentration of precursor salt solution (AgNO3, 10 and 20 mM) on antimicrobial activity against Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and yeast Candida albicans, and UV protection factor (UPF) of cotton fabric were studied.
The presence of chitosan/lignin coating on the cotton fabric was confirmed by FTIR and XPS analyses. XPS high resolution Ag3d spectra of nano-finished cotton fabrics indicated the formation of Ag2O NPs. Keeping in mind that sodium borohydride is very strong reducing agent and high sensitivity of XPS, it is assumed that thin layer of Ag2O was formed on the surface of metallic NPs because Ag is prone to oxidation. FESEM analysis revealed the formation of small spherical NPs with average diameters of 34-36 nm independently of bilayers number. In contrast, an increase of bilayers as well as the increase in concentration of AgNO3 solution led to higher Ag content confirmed by AAS measurements.
Fabricated textile nanocomposites provided extraordinary antimicrobial activity against all tested microorganisms. Small size and high reactivity of synthesized NPs ensured maximum 99.9-100% reduction of microbial colonies. A selected sample which was coated with 4 bilayers and impregnated with 10 mM solution of AgNO3 was shown not to be cytotoxic on human keratinocyte cells (HaCaT) that are main constituent of the outer layer of skin.
Maximum UV protection 50+ was accomplished after impregnation of fabrics. Unlike the concentration of AgNO3 solution, the number of bilayers play important role in UV protection
Пречишћавање отпадних вода које садрже шестовалентни хром редукцијом наночестицама елементарног гвожђа и адсорпцијом на сепиолиту и валоризација искоришћених материјала као сировина за добијање традиционалне керамике
No full textУ овом техничком решењу се унапређује поступак пречишћавања отпадне воде из процеса електрохемијског хромирања, које садрже токсични шестовалентни хром. Уместо коришћења стандардних редукционих средстава, предложена је примена наночестица елементарног гвожђа, nZVI, синтетисаних еколошким, „green“ поступком, коришћењем екстракта опалог сувог лишћа храста, а настали тровалентни хром се не таложи у облику Cr(OH)3, већ се уклања адсорпцијом на јефтином минералу сепиолиту из домаћих лежишта. Карактеризацијом nZVI утврђено је да су честице приближно сферне, реда величине 20 nm, веома агломерисане, са великим уделом органске материје из екстракта. Ефикасност nZVI као редукционог и адсорпционог средства је испитана на узорцима отпадне воде из фабрике ППТ-ТМО и при том је утврђена минимална доза која потпуно редукује присутан шестовалентни до тровалентног хрома. Након третмана отпадне воде потребном дозом nZVI, одређена је потребна доза сепиолита за постизање граничних вредности емисија за хром и гвожђе, које се отпушта у воду услед оксидације nZVI. Овим техничким решењем је предвиђено да се засићено редукционо средство и засићени адсорбент не регенеришу, јер тиме настају нове отпадне воде, већ да се користе као сировине за производњу керамике уместо чистих глинених минерала. Синтеровањем на различитим температурама смеша засићеног nZVI и засићеног сепиолита, уз додатак чистог сепиолита у различитим уделима, оптимизовани су услови за добијање керамичких материјала чија је притисна чврстоћа приближно иста као материјала који су добијени од чистог сепиолита, а излуживање хрома значајно мање од граничне вредности која је дефинисана одговарајућим стандардом.Техничко решење категорије М82 – Ново техничко решење (метода) примењено на националном ниво
Synthesis, characterization and mechanical properties of geopolymers based on fly ash and zeolites
No full textGlobal warming and greenhouse gas emissions represent great challenges nowadays. It has been estimated that the construction industry contributes 36% to carbon dioxide emissions, with the largest quantities emitted during the production of Portland cement. Considering the seriousness of this issue, a need for the development of more sustainable and environmentally friendly construction materials, such as geopolymers, arises. Geopolymers are materials that can be synthesized at low temperatures using waste raw materials, which reduce both carbon footprint and waste. This study involved the synthesis of geopolymers based on fly ash and zeolites in various mass ratios (0%, 20%, 40%, 60%, 80%, and 100% of fly ash). The starting materials were characterized using Fourier-transform Infrared Spectroscopy (FTIR), X-ray Fluorescence Spectroscopy (XRF) and X-ray Powder Diffraction (XRPD). The resulting products were also characterized using FTIR. The physical and mechanical properties of the obtained materials, such as compressive strength and maximum water adsorption capacity, were determined. The results have shown that the ratio of the starting raw materials significantly affects the properties of the obtained material. The compressive strength ranged from 2 to 11 MPa, while the maximum amount of absorbed water varied between 8 % and 25 %
The impact of extraction parameters on the determination of total polyphenol content in spice samples
No full textSpices are edible parts of plants that have been used in food for centuries to enhance flavor. They contain varying amounts of macronutrients, micronutrients, and trace elements, as well as a wide range of complex organic molecules. Among these, compounds with antioxidant and anti-inflammatory role are particularly significant. Antioxidants are substances that neutralize free radicals and prevent the oxidation of other compounds; polyphenols are one example of such compounds. This study aimed to compare different methods of polyphenol extraction from ten commonly used spices. The extraction process involved varying the type of solvent used (water, methanol, and ethyl acetate) and the temperature at which the extraction was conducted. The total amount of extracted polyphenols was determined using the Folin-Ciocalteu reagent and measured by spectrophotometric method. The results demonstrated that the extraction parameters have a substantial impact on the quantity of polyphenols obtained and that the preparation of spice samples as a complex matrix is a very specific and important step that significantly affects the efficiency of the determination of these compounds. Additionally, the concentration of polyphenols varied significantly among the different spices. The highest levels of polyphenols concentration were found in basil, oregano, and cinnamon, while the lowest levels were observed in sesame and coriander
Crystallographic and quantum chemical studies of 2,2’-dipyridylamine–diethylbarbituric acid co-crystal
No full textThe diethyl derivative of barbituric acid (H2debarb) belongs to a class of drugs that have a wide
range of uses as sedatives, anticonvulsants, and anaesthetics. It is a strong hydrogen bond donor
via two –NH groups and a weak acceptor via three carbonyl O atoms.
2,2′-Dipyridylamine (dipya) is a charge-transferring organic base that can exist in a variety of
protonation states, adopting one of nine coordination modes. A co-crystal (H2debarb)(dipya)2,
was prepared by solvent evaporation method from the H2O/EtOH reaction mixture containing
Na(Hdebarb) and dipya in molar ratio 1:1. Single crystal X-ray analysis revealed that the
asymmetric unit of the co-crystal consists of one H2debarb and two dipya moieties linked by
strong N/C–H···O/N interactions. The main structural feature is a supramolecular tape formed by
N/C–H···O/N interactions, while weak π···π stacking interactions were observed between the
tapes. The calculation of the molecular electrostatic potential surfaces revealed the most
electrophilic and nucleophilic parts, while the Hirshfeld surfaces and 2D fingerprint plots
allowed the analysis of the intermolecular interactions and quantification of the contribution of
different intermolecular contacts present in the crystal structure of co-crystal.
Crystallographic data: C28H30N8O3, triclinic, P–1, a = 11.4015(5), b = 12.1485(4),
c = 12.1839(5) Å, α = 70.012(3), β = 64.655(4), γ = 64.500(4) °, V = 1350.68(11) Å3, Z = 2,
R1 = 0.0412, wR2 = 0.1012 for 352 parameters and 3835 observed reflections
Corrosion characteristics of Ag40Cu30Zn30 and Ag25Cu52.5Zn22.5 alloys in natural seawater of Marmara Sea
No full textInvestigation of factors affecting the similar corrosion behaviour of two silver brazing alloys with different silver content was the primary goal of this study. The comparative study aims to present and explain why different compositions of the alloys that belong to the same ternary Ag-Cu-Zn system lead to a very similar corrosion resistance in the natural seawater. Electrochemical methods used in the research were open circuit potential (OCP), linear polarization resistance (LPR), linear sweep voltammetry (LSV) and Tafel extrapolation. The water of the Sea of
Marmara was analyzed by ICP-OES, pH meter and conductometer. The determined corrosion current densities for both alloys were similar and under 10 A/cm2. This similarity, despite the significant difference in silver content, could be mainly ascribed to the difference in the phase composition of these two alloys
The corrosion resistance of the nanostructured modified ultrafine-grained titanium in Ringer's solution
No full textTo optimize corrosion resistance, as one of the important factors for biocompatibility of the
metallic implants, the titanium-based materials can be modified by different treatments,
including severe plastic deformation (SPD) and anodic oxidation. In the present study, oxide
layer on the surface of ultrafine-grained titanium (UFG cpTi) was formed using anodic
oxidation in 1 M H3PO4 + NaF solution, at room temperature for 60 minutes. The nanotubes
morphology was studied using field emission scanning electron microscopy (FESEM). The
FESEM microphotographs showed that anodic oxidation of ultrafine-grained titanium in the
selected solution can lead to the formation of a highly regular oxide layer with nanotubes. This
study aimed to determine the corrosion resistance of titanium after high-pressure torsion
(HPT) and anodic oxidation. Corrosion resistance was tested in Ringer's solution with a pH
value of 5.5 at 37 °C, in order to simulate the environment in the human body. The ultrafinegrained titanium, before and after anodic oxidation, was analyzed by electrochemical
impedance spectroscopy (EIS) and potentiodynamic polarization. The inner barrier and outer
porous surface layers were highly resistant with capacitive behaviour, but the ultrafine-grained
titanium with an oxide layer with nanotubes on the surface showed improved corrosion
resistance
Fractionation of juniper berry essential oils obtained by classical and microwave-assisted hydrodistillation
No full textThe composition of the essential oil of juniper (Juniperus communis L.) depends on plant age, geographical origin, fruit maturity, etc. Nevertheless, juniper essential oil mainly consists of terpene hydrocarbons: monoterpenes (up to 85%) and sesquiterpenes ( up to 27%), along with their oxygenated derivatives (up to 4%). Consequently, researchers look for the most effective methods for separating juniper essential oils into pure components or their fractions. This research is focused on isolating essential oil fractions and analyzing their composition during hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD) processes. It was observed that the composition of the juniper essential oils undergoes significant changes during the process. The concentration of easily volatile components was the highest in the early fractions, while less volatile components dominated the final fraction. Comparing the fractionation techniques, it can be concluded that a similar percentage of components are separated within 10 minutes using HD compared to 9 minutes with MAHD. Furthermore, when using juniper fruits that were pre-swollen for 24 hours, the HD for 10 minutes gave better results than the MAHD for 9.5 minutes
Komparativne karakteristike ulja semena šljive dobijenih superkritičnom i Soxhletovom ektrakcijom
No full textIntroduction/Aim. Plums, as one of the oldest types of fruits, are very important in the human diet. The most common varieties of plums cultivated in the territory of Bosnia and Herzegovina are Požegača, Čačanska lepotica, Čačanska rodna and Valjevka. They belong to the group of basic fruits rich in various vitamins and minerals. In addition, plum seed oil is used in the cosmetic industry. This oil is a rich source of biologically active components with proven biological effects – it hydrates the skin and improves its elasticity; the skin easily absorbs it without leaving a greasy film on the surface. The aim of this study was to find the optimal method for isolating fatty oil from the seeds of four types of plums with the best characteristics. Their potential as raw material in the cosmetic industry through the application of supercritical and Soxhlet extraction and their characterization was examined. Methods. Fatty oils were extracted by conventional Soxhlet extraction with non-polar organic solvent and by supercritical extraction with carbon dioxide. The AOAC 930.15 method was used to determine the moisture content of the plum seeds. The oils were characterized by determining the organoleptic characteristics, as well as the acid, iodine, saponification and peroxide number. Results. The fattiest oil was obtained from the pits of the Čačanka rodna plum using the both extraction methods, supercritical and Soxhlet extraction. Fatty oil of Požegača had the lowest values of iodine and peroxide number, while the acid and saponification number were the lowest within the oil from Valjevka and Čačanka rodna, respectively. Conclusion. Both extraction methods showed good extraction yields, with higher extraction capacity using Soxhlet extraction. Čačanka rodna had the highest amount of oil. Fatty oils from all varietes showed excellent characteristics, so the plum kernels can be potentially used for obtaining fatty oil for cosmetic purposes due to its beneficial effect on the skin.Uvod/Cilj. Šljive, kao jedna od najstarijih vrsta voća, veoma su važne u ljudskoj ishrani. Najzastupljenije sorte šljive koje se gaje na teritoriji Bosne i Hercegovine su požegača, čačanska lepotica, čačanska rodna i valjevka. Šljive spadaju u grupu bazičnog voća bogatog vitaminima i mineralima. Pored toga, koristi se i seme šljive kao izvor ulja koje nalazi primenu u kozmetičkoj industriji. Ovo ulje je bogat izvor biološki aktivnih komponenata sa dokazanim biološkim delovanjem – hidrira kožu i poboljšava njenu elastičnost; koža ga lako upija, a na njenoj površini ne ostavlja mastan film. Cilj ovog rada bilo je pronalaženje optimalnog načina izolovanja masnog ulja semena četiri vrste šljiva najboljih karakteristika. Ispitivani su potencijali sirovog materijala u kozmetičkoj industriji primenom superkritične i Soxhletove ekstrakcije, kao i njihova karakterizacija. Metode. Korišćeno je seme četiri vrste šljive: valjevka, čačanska lepotica, čačanska rodna i požegača (gajenih u selu Borogovo, opština Osmaci, Bosna i Hercegovina). Za određivanje sadržaja vlage u semenu šljive korišćena je metoda AOAC 930.15. Masna ulja ekstrahovana su konvencionalnom Soxhletovom ekstrakcijom nepolarnim organskim rastvaračem i superkritičnom ekstrakcijom ugljen-dioksidom. Ulja su okarakterisana određivanjem organoleptičkih karakteristika, kao i kiselinskog, jodnog, saponifikacionog i peroksidnog broja. Rezultati. Superkritičnom ekstrakcijom izolovane su manje količine ulja iz semena šljiva nego primenom konvencionalne Soxhletove ekstrakcije (kod semena sve četiri vrste šljive). Najveći sadržaj ulja dobijen je iz semena šljive čačanska rodna (primenom obeju metoda ekstrakcije). Najniže vrednosti jodnog i peroksidnog broja imalo je masno ulje požegače, te ga možemo smatrati najstabilnijim. Kiselinski i saponifikacioni broj bili su najniži kod ulja dobijenog iz semena valjevke i čačanske rodne. Zaključak. Obe metode ekstrakcije pokazale su dobre prinose ekstrakcije, sa većim kapacitetom ekstrakcije primenom Soxhletovog aparata. Najveću količinu ulja imala je čačanska rodna, a hemijski najstabilnije bilo je ulje semena valjevke. Masna ulja svih sorti mogu se koristiti u kozmetičke svrhe
Predviđanje modula elastičnosti, granice razvlačenja i zatezne čvrstoće u biokompatibilnim legurama titanijuma
No full textBiocompatible titanium alloys possess a balanced set of improved mechanical properties and good biocompatibility, making them crucial materials in biomedical engineering. There is an increasing demand for these new alloys with superior properties. Furthermore, there is a need to understand the relationship between parameters and properties, and machine learning is being applied to make the whole process cheaper and more efficient. The aim of this study is to develop accurate machine learning models for predicting mechanical properties: modulus of elasticity, tensile strength, and yield strength, specifically using the Extra Trees Regressor model. Compared to the previous results, an improvement of the elastic modulus prediction model was observed after the inclusion of data on heat treatment parameters and Poisson’s ratio, as seen in the reduced MAE from 7.402 to 7.160 GPa. Models were built to predict the values of tensile strength and yield strength, where iron and tin were shown as most important features respectively, while the correlation coefficients for the test set were 0.893 and 0.868.Biokompatibilne legure titanijuma imaju uravnoteženu kombinaciju poboljšanih mehaničkih svojstava i dobre biokompatibilnosti, što ih čini važnim materijalima u biomedicinskom inženjeringu. Postoji sve veća potražnja za ovim novim legurama sa superiornim svojstvima. Pored toga, postoji potreba za razumevanjem odnosa između parametara i svojstava, a mašinsko učenje se koristi kako bi ceo proces bio jeftiniji i efikasniji. Cilj ove studije je razvijanje preciznih modela mašinskog učenja za predviđanje mehaničkih svojstava: modula elastičnosti, zatezne čvrstoće i granice razvlačenja, specifično korišćenjem modela „Extra Trees Regressor“. U poređenju sa prethodnim rezultatima, uočeno je poboljšanje modela za predviđanje modula elastičnosti nakon uključivanja podataka o parametrima termičke obrade i Poasonovog odnosa. Ovo se odrazilo na smanjenje MAE sa 7,402 na 7,160 GPa. Kreirani su modeli za predviđanje vrednosti zatezne čvrstoće i granice razvlačenja, pri čemu su gvožđe i kalaj bili najznačajnije karakteristike, dok su koeficijenti korelacije za testni set bili 0,893 i 0,868