8639 research outputs found
Sort by
Valorization of Aronia melanocarpa Pomace: A Sustainable Source of Bioactive Compounds for Developing Colored Healthcare Textiles, Biomedical Hydrogels, and Green Corrosion Inhibitor
No full textThis interdisciplinary study explores the potential of bioactive compounds from Aronia melanocarpa pomace, a juice industry by-product. The ethanol extract of the pomace was analyzed using HPLC, revealing key polyphenolic acids and anthocyanins. The extract exhibited outstanding antioxidant activity (100% as measured by the ABTS assay and 98.23% as measured by the DPPH assay) and >99% antibacterial efficacy against E. coli and S. aureus. This bioactive extract was utilized in a one-step process to dye and functionalize textiles (wool, silk, cellulose acetate, cotton, and viscose), with cotton and viscose suited for colored disposable bioactive textiles, particularly protective healthcare textiles, due to strong antioxidant (>97% as measured by the ABTS assay and >76% as measured by the DPPH assay) and antibacterial (>75% for E. coli and >80% for S. aureus) properties. The aronia pomace extract was also incorporated into newly synthesized starch/gelatin hydrogels with a compression modulus of 0.041–0.127 MPa and equilibrium swelling ratios of 3.33–4.26 g/g. Functionalized hydrogels demonstrated over 99% ABTS antioxidant activity, while the antibacterial efficacy against E. coli and S. aureus exceeded 70% and 97%, respectively. These properties, combined with the hydrogels’ ability to control the release of extract compounds, make them adequate for wound care applications. The extract’s effectiveness as a green inhibitor for carbon steel, with inhibition efficiency surpassing 94% at a concentration of aronia pomace extract of 100 ppm, was confirmed by electrochemical methods. Moreover, the extract predominantly retards the cathodic reaction. The current research represents the first exploration of alternative and green sustainable technologies for developing novel products based on aronia pomace extract
Испитивање узрока корозије и оштећења унутрашњих металних компонената аутомобила
No full textThe extent of corrosion and the underlying causes of damage to the interior metal components of a one-year-old automobile from a known brand, owned by a rental car company in Serbia, were investigated. The vehicle's interior, including upholstery and carpeting, showed no chemical spills or other damage. The solution obtained after rinsing a carpet sample from the car floor exhibited neutral pH. The corrosion behavior of the analyzed samples was determined using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and linear sweep voltammetry (LSV, Tafel method). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses showed that corrosion products taken from corroded steel parts contain akaganeite β-FeO(OH) and iron (II) chloride. FTIR analysis of the organic coating revealed that the applied epoxy layer was insufficiently crosslinked, making it permeable to moisture and chloride ions. Electrochemical corrosion measurements on steel with a similar chemical composition demonstrated an increased corrosion rate in a solution containing dissolved corrosion products compared to a reference solution. This accelerated corrosion was attributed to the acidity of akaganeite and iron (II) chloride, formed due to the vehicle's exposure to a humid and chloride-rich environment.У раду су испитане размере корозије и основни узроци оштећења унутрашњих
металних компоненти аутомобила познате марке, који је у власништву компаније за
изнајмљивање аутомобила у Србији и који је био у употреби годину дана. Унутрашњост
аутомобила, тапациринзи и тепих на поду аутомобила, су очувани, без трагова оштећења,
а такође није утврђено присуство неке корозивне хемикалије. Раствор настао после
испирања делова тепиха узетог са пода аутомобила се понашао неутрално. Корозивно
понашање анализираних узорака одређено је коришћењем спектроскопије електрохемијске импеданције, линеарне поларизационе отпорности и линеарне волтаметрије.
Резултати анализе методaмa рендгенске дифракције (XRD) и инфрацрвене спектроскопије са Фуријеовом трансформацијом (FTIR) показали су да производи корозије узети
са кородираних челичних делова садрже акаганеит (β-FeO(OH)) и гвожђе(II)-хлорид.
FTIR анализа органске превлаке открила је да је примењена епоксидна превлака
недовољно умрежена, што је чини пропусном за влагу и хлоридне јоне. Електрохемијска
мерења корозије на челику сличног хемијског састава са челиком коришћеним за израду
аутомобила су показала повећану брзину корозије у раствору који садржи растворене
производе корозије у поређењу са референтним раствором. Ова убрзана корозија приписује се киселости акаганеита и гвожђe(II)-хлорида, који су настали услед изложености
делова возила влажном и хлоридима богатом окружењу
Blackcurrant Extract as a Botanical Deodorant Alternative via Microbiome Modulation
No full textIntroduction: Unpleasant armpit odor is caused by specific bacteria, mainly
by Corynebacterium species, that convert sweat secretions into volatile and
malodorous compounds. In contrast, another mayor habitant of the axillary
microbioom, Staphylococcus epidermidis, does not have this property.
Therefore, the balance between these bacterial strains can affect the
production of unpleasant odor. Since the use of conventional antiperspirants
leads to an enrichment of odor-causing species, this does not solve the
problem but actually makes it worse. The use of natural extracts such as
blackcurrant extract (BCE) offers an interesting alternative to deodorants,
helping to maintain microbial balance.
Here, we evaluated whether and how BCE has an effect on the main
microbial components (represented by S. epidermidis and C. striatum) of the
armpit microbiome. ..
Failure Analysis Of A Roll Journal In A Paper Machine
No full textThe failure of the paper machine upper roll made of 42CrMo4 steel was investigated. The roll journal was previously repaired by weld build-up. The fracture occurred at the roll journal within the bearing shortly after the roll was put into service. The microstructure of the base material and the weld deposit was investigated using light microscopy. The fracture surface was examined using a stereo microscope and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDS). The mechanical properties were examined by measuring Brinell hardness along the line from the center to the surface and the weld deposit. Liquid penetrant testing did not reveal any surface cracks. The hardness of the weld deposit was between 240 and 270 HB, in accordance with the specifications. However, the hardness of the base metal was 194 HB, which was significantly lower than that expected for the annealed 42CrMo4 steel. The microstructure of the base metal consisted of pearlite, grain-boundary ferrite and intragranular ferrite, while the microstructure of the weld metal consisted of fine ferrite grains. The microstructural examination also revealed coarse, elongated cavities at the border between the weld deposit and the base material and smaller rounded cavities between the layers of the weld build-up. Ratchet marks at the fracture surface along the circumference of the roll journal indicated fracture initiation at multiple points near the surface of the roll journal. Examination under a stereo microscope revealed large cracks near the surface and beach marks indicating a fatigue fracture. SEM revealed elongated coarse cavities and large cracks near the fracture initiation sites. EDS analysis revealed traces of calcium and silicon, indicating the formation of the inclusions at the base metal/weld metal interface. At higher magnifications, fatigue striations were detected around the fracture origins. All fracture initiation sites along the roll journal rim were in the vicinity of the fillet radius. It was concluded that the failure of the paper machine roll was caused by the fatigue fracture initiated at the inclusions in the area of increased stress concentration near the roll journal fillet radius
Ispitivanje IBR-IR za analizu i kontrolu zavarivanja trenjem rotacijom nerđajućih čelika AISI 304L i AISI 316L
No full textThe quality of the weld primarily depends on the parameters used during the welding process, including rotational speed, friction time and pressure, and forging time and pressure. Initially, welding operations are carried out on austenitic stainless steel bars, specifically from the AISI 304L and AISI 316L families, under a constant rotational speed. The first objective is to analyse the steel AISI 304L using the effect of two simultaneous parameters, namely two different forging times and two different forging pressures. The second objective is to evaluate the effect of five different friction phase times on AISI 316L, while keeping the other parameters constant, including friction pressure and forging pressure. Subsequently, a quality control is performed on all welded joints using non-destructive testing (NDT) techniques such as dye penetration testing, X-rays, and ultrasonics, in order to assess the impact of the aforementioned welding parameters on the quality of the joints. The results obtained indicate the presence of defects in some of the welded joints, estimated at 25 % in terms of joints, predominantly associated with low forging times or pressures.Kvalitet zavarenog spoja uglavnom zavisi od primenjenih
parametara tokom postupka zavarivanja, uključujući brzinu
rotacije, vreme i pritisak trenja, kao i vreme i pritisak iskivanja. Zavarivanje je izvedeno sa epruvetama od čelika tipa
AISI 304L i AISI 316L, sa konstantnom brzinom rotacije.
Prvi zadatak je analiza čelika AISI 304L korišćenjem efekta
dva simultana parametra, zapravo, dva različita vremena
iskivanja, i dva različita pritiska iskivanja. Drugi zadatak je
procena uticaja pet različitih vremena faze trenja kod čelika
AISI 316L, pri konstantnim ostalim parametrima, uključujući
pritisak trenja i pritisak iskivanja. Zatim je izvedena kontrola kvaliteta svim zavarenim spojevima ispitivanjem bez
razaranja (IBR), metodama penetrantima, rendgenskim zračenjem i ultrazvukom, radi procene dejstva gore navedenih
parametara zavarivanja na kvalitet spojeva. Dobijeni rezultati pokazuju prisustvo grešaka kod nekih zavarenih spojeva, u obimu 25 % s obzirom na spojeve, koji su u najvećoj
meri povezani sa kratkim vremenima i malim pritiscima
iskivanja
Correlation between morphology and hardness of electrolytically produced copper thin films
No full textCorrelation between morphology of electrolytically produced copper thin films and their hardness has been considered. The Cu films were electrodeposited by galvanostatic (DC) and by the pulsating current (PC) regimes on cathodes of limiting values of hardness (Cu, brass, and Si(111)) from the basic sulfate electrolytes without and with addition of leveling/brightening additives, without and with various ways of electrolyte stirring (ultrasound and magnetic stirring), and characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Hardness of Cu films was determined by microindentation and by application of composite hardness models (CHMs), such as Cheng–Gao (C–G) and Korsunsky (K), with the aim to eliminate a contribution of cathode hardness in the measured film hardness and to determine the absolute hardness of the Cu films. The fine-grained films obtained from the basic sulfate electrolyte were harder than the smooth film obtained from the electrolyte with additives and that obtained by the PC regime, indicating that the PC produced film represents transitional form between these two types of the films. The obtained values of the absolute film hardness in the 1.135–1.647 GPa range were in line with already published values for the electrolytically produced Cu thin films, clearly indicating on successful implementation of CHMs in determination of the absolute hardness of thin films. Correlation between morphology and hardness of Cu films was discussed by the basic laws of electrocrystallization and phenomena on boundary among grains during microindentation processes
Improved surface characteristics of the ultrafine-grained Ti-13Nb-13Zr alloy using anodic oxidation
No full textThe ultrafine-grained (UFG) Ti-13Nb-13Zr alloy (TNZ), which was obtained using severe plastic deformation (SPD) was used as tested material in this study. In order to obtain ultrafine-grained structure of titanium alloy, severe plastic deformation was used. Actually, high-pressure torsion process (HPT), at room temperature, with 5 rotations and 4.1 GPa pressure, was conducted. After this surface and bulk materials modification, the surface was once again modified using anode oxidation in the solution of orthophosphoric acid and sodium-fluoride, during 90 minutes. The field emission scanning electron microscopy (FE-SEM) was used to characterize the morphology of the modified surface. Biocompatibility of the titanium alloy before and after surface modification was estimated by dye exclusion test (DET) and agar diffusion test. The results of the biocompatibility tests showed that the titanium alloy before and after the surface modification was not cytotoxic. The nanoindentation test was used to determine values of surface modulus of elasticity and nanohardness before and after surface modification. Results showed a drop in these values after anode oxidation
Application of pumpkin-leaf protein concentrate as a matrix component for the encapsulation of folic acid
No full textThis study investigates the valorization of pumpkin leaves, an underutilized agricultural byproduct, to produce plant-based protein concentrate and apply this concentrate as a novel component for developing encapsulation matrices. Composite zein/pumpkin-leaf protein concentrate/alginate matrices were structured using a pH-driven method for folic acid (FA) encapsulation. This approach afforded spherical, compact, and uniform nanoparticles, which were formed via intermolecular hydrogen bonding. These nanoparticles successfully encapsulated FA with an encapsulation efficiency of 79.09 % and a loading content of 15.82 %. The thermal analysis of all nanoparticle formulations showed compatibility among their components. The antioxidant activity and storage stability of control nanoparticles were improved by encapsulating FA and increasing its content. Notably, the nanoparticles could release FA during simulated digestion. These results emphasize the potential of the developed nanoparticles as novel nutraceuticals or ingredients for use in functional food formulations
Polymeric Nanosystems: A Breakthrough Approach to Treating Inflammation and Inflammation Related Diseases
No full textInflammation processes can cause mild to severe damage in the human body and can lead to a large number of inflammation-related diseases (IRD) such as cancer, neural, vascular, and pulmonary diseases. Limitations of anti-inflammatory drugs (AID) application are reflected in high therapeutic doses, toxicity, low bioavailability and solubility, side effects, etc. Polymeric nanosystems (PS) have been recognized as a safe and effective technology that is able to overcome these limitations by AID encapsulation and is able to answer to the specific demands of the IRD treatment. PS are attracting great attention due to their versatility, biocompatibility, low toxicity, fine-tuned properties, functionality, and ability for precise delivery of anti-inflammatory drugs to the targeted sites in the human body. This article offers an overview of three classes of polymeric nanosystems: a) dendrimers, b) polymeric micelles and polymeric nanoparticles, and c) polymeric filomicelles, as well as their properties, preparation, and application in IRD treatment. In the future, the number of PS formulations in clinical practice will certainly increase
Mechanical Stimulation of Red Blood Cells Aging: Focusing on the Microfluidics Application
No full textHuman red blood cells (RBCs) are highly differentiated cells, essential in almost
all physiological processes. During their circulation in the bloodstream, RBCs are exposed
to varying levels of shear stress ranging from 0.1–10 Pa under physiological conditions to
50 Pa in arterial stenotic lesions. Moreover, the flow of blood through splenic red pulp and
through artificial organs is associated with brief exposure to even higher levels of shear
stress, reaching up to hundreds of Pa. As a result of this exposure, some properties of
the cytosol, the cytoskeleton, and the cell membrane may be significantly affected. In this
review, we aim to systematize the available information on RBC response to shear stress by
focusing on reported changes in various red cell properties. We pay special attention to the
results obtained using microfluidics, since these devices allow the researcher to accurately
simulate blood flow conditions in the capillaries and spleen