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Green leaves: from oil processing byproducts to novel proteins nanoparticle structures
No full textGiven their high protein content and widespread use, by-products of the oil processing sector, such as pumpkin leaves, are promising alternative protein sources. The most abundant protein on the planet is found in the soluble protein fraction of leaves, commonly referred to as white food protein. This protein is mainly composed of the photosynthetic enzyme RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase). Food proteins are intriguing GRAS (Generally Recognized As Safe) components for nanoparticle delivery systems due to their unique functional properties, enabling the encapsulation of hydrophilic and lipophilic bioactive substances. These traits include the ability to produce gels and emulsions. Furthermore, food proteins can bind bioactive compounds offering opportunities for improved protection until their release. This research serves as proof of concept that the cold gelation protocol, after optimisation, can be effectively employed for the creation of novel protein nanoparticles. The white protein fraction from leaves was isolated using a three-step process, consisting of screw pressing, thermal coagulation, and acid precipitation.
Protein nanoparticles (50–150 nm) were prepared by employing a cold gelation protocol with calcium as the cross-linking cation. Nanoparticle characteristics including size, surface charge, and hydrophobicity, were adjusted by changing the cross-linking cation concentration (1–5 mmol/dm3), environmental pH (7–9), and temperature of the alkaline treatment (70–100 °C at pH 12). The yield of protein nanoparticle and their morphology characteristics, determined via SEM imaging, were the unique parameters for validating and selecting the optimal ultracentrifugation conditions for protein suspensions. For this purpose, time (10–60 min) and rotation speed (40000–80000 rpm) were varied using the OptimaTM XPN-100 ultracentrifuge. The obtained nanoparticles exhibited a uniform size distribution and spherical shape. A lower pH value and higher concentration of cross-linking cations found to promote the development of larger and surface-charged nanoparticles. Protein conformation analysis revealed that the calcium ions likely protected the negative charges on the protein polypeptide chains and served as a salt bridge, enabling the polypeptide chains to approach each other. These findings have significant implications for the production of food protein nanoparticles appropriate for the synthesis of novel carriers for bioactive substances
Tehnološki postupak za dobijanje aerogelova skroba velike poroznosti
No full textPredloženo tehničko rešenje opisuje tehnološki postupak za dobijanje aerogelova skroba velike poroznosti. Ovim tehničkim rešenjem prevazilaze se ekološki problemistvaranja i akumulacije otpada. Aerogelovi su proizvedeni od biokompatibilnih materijalaiz obnovljivih izvora upotrebom zelenog medujuma (natkritičnog ugljen(IV)-oksida). Zeleni medijum se u potpunosti uklanja iz finalnog proizvoda i može da se reciklira nakon proizvodnje materijala.Predloženim tehnološkim postupkom proizvodnje omogućava se ušteda vremena i energije za proizvodnju polisaharidnih aerogelova koji imaju poroznost do 82%.Dobijeni aerogelovi se mogu upotrebiti u medicini za tretiranje vlažnih rana jer apsorbuju do 420% okolne tečnosti.Vlažne rane proizvode značajnu količinu eksudata ili tečnosti i njihov tretman je ključan za promovisanje pravilnog zarastanja i sprečavanje infekcija. Dodatno,usled biodegradabilnosti skroba korišćenjem proizvedenih aerogelova izbegava se akumulacija otpada nakon upotrebe istog.Tehničko rešenje kategorije M85 - Novo tehničko rešenje (nije nekomercijalizovano
Films based on TEMPO-oxidized chitosan nanoparticles: Obtaining and potential application as wound dressings
No full textA series of novel films based on TEMPO-oxidized chitosan nanoparticles were prepared by casting method. Fourier transform infrared spectroscopy (FTIR) was employed to ascertain the chemical structure of TEMPO-oxidized chitosan. The surface morphology of the TEMPO-oxidized chitosan nanoparticles was analyzed by atomic force microscopy (AFM). The physicochemical (area density, thickness, iodine sorption, roughness), functional (moisture sorption, liquid absorption capacity, weight loss upon contact with the liquid, and water vapor transmission rate), antibacterial, and antioxidant properties of films based on TEMPO-oxidized chitosan nanoparticles were also investigated. The physicochemical properties of the films varied widely: area density ranged from 77.83 ± 0.06 to184.46 ± 0.05 mg/cm2, thickness varied between 80.5 ± 1.6 and 200.5 ± 1.6 μm, iodine sorption spanned from 333.7 ± 2.1 to166.4 ± 2.2 mg I2/g, and roughness ranged from 4.1 ± 0.2 to 5.6 ± 0.3 nm. Similarly, the functional properties also varied significantly: moisture sorption ranged from 4.76 ± 0.03 to 9.62 ± 0.11 %, liquid absorption capacity was between 129.04 ± 0.24 and 159.33 ± 0.73 % after 24 h, weight loss upon contact with the liquid varied between 31.06 ± 0.35 and 45.88 ± 0.58 % after 24 h and water vapor transmission rate ranged from 1220.10 ± 2.91to1407.77 ± 5.22 g/m2 day. Despite the wide variations in physicochemical and functional properties, all films showed maximum bacterial reduction of Staphylococcus aureus and Escherichia coli, although they exhibited low antioxidant activity. The results suggest that the films could be effectively utilized as antibacterial wound dressings
Alkaline electrochemical oxygen reduction boosted by trimetallic palladium–copper–gold nanoparticles
No full textA Pd-Cu-Au/C nanocatalyst with a low content of Cu (8.2 at %) and Au (4.4 at %), and an average crystallite size of about 2 nm was synthesized by employing a one-pot two-steps borohydride reduction method in the presence of sodium citrate, characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy and examined for the oxygen reduction reaction (ORR) in an alkaline solution. Pd/C and Pd-Cu/C catalyst with 17 at % Cu, which were synthesized by the same method, and a commercial Pt/C were used for comparison. In addition, Pd-Cu-Au/C and Pd-Cu/C nanocatalysts were treated in acid with a purpose of their dealloying. The electrochemically active surface area of Pd was determined from COads desorption. It was found that the ORR on all catalysts follows first order kinetics with respect to O2 with four electrons transferred per O2 molecule. The catalysts were subjected to a short-term cycling stability test. Pd-Cu/C and Pd-Cu-Au/C were more active for ORR than Pd/C and Pt/C. The acid-treated catalysts exhibited higher activity compared to their untreated counterparts; both initially and after the stability test (up to 1.7 times in specific activity and 2 times in mass activity). The catalyst with the highest specific and mass activity after the stability test was the acid-treated Pd-Cu-Au/C which surpassed Pd/C by a factor of up to 2.5 in specific activity and 5.7 in mass activity. It was concluded that the acid treatment leads to a major dissolution of Cu from the nanoparticles, thus leaving a highly disordered Pd structure exhibiting increased activity for the ORR, while Au stabilizes Pd structure contributing to better performance after the stability test
Eco-Friendly g-C3N4/Carboxymethyl Cellulose/Alginate Composite Hydrogels for Simultaneous Photocatalytic Degradation of Organic Dye Pollutants
No full textThe presented study was focused on the simple, eco-friendly synthesis of composite hydrogels of crosslinked carboxymethyl cellulose (CMC)/alginate (SA) with encapsulated g-C3N4 nanoparticles. The structural, textural, morphological, optical, and mechanical properties were determined using different methods. The encapsulation of g-C3N4 into CMC/SA copolymer resulted in the formation of composite hydrogels with a coherent structure, enhanced porosity, excellent photostability, and good adhesion. The ability of composite hydrogels to eliminate structurally different dyes with the same or opposite charge properties (cationic Methylene Blue and anionic Orange G and Remazol Brilliant Blue R) in both single- and binary-dye systems was examined through adsorption and photocatalytic reactions. The interactions between the dyes and g-C3N4 and the negatively charged CMC/SA copolymers had a notable influence on both the adsorption capacity and photodegradation efficiency of the prepared composites. Scavenger studies and leaching tests were conducted to gain insights into the primary reactive species and to assess the stability and long-term performance of the g-C3N4/CMC/SA beads. The commendable photocatalytic activity and excellent recyclability, coupled with the elimination of costly catalyst separation requirements, render the g-C3N4/CMC/SA composite hydrogels cost-effective and environmentally friendly materials, and strongly support their selection for tackling environmental pollution issues
Comparison of Quantitative and Qualitative EDXRF Analysis for Provenance Study of Archaeological Ceramics
No full textThe most common scientific analysis of archaeological ceramics aims to determine the raw material source and/or production technology. Scientists and archaeologists widely use XRF-based techniques as a tool in a provenance study. After conducting XRF analysis, the results are often analyzed using multivariate analysis in addition to interpretation and conclusions. Various multivariate techniques have already been applied in archaeological ceramics provenance studies to reveal different raw material sources, identify imported pieces, or determine different production recipes. This study aims to evaluate the results of multivariate analysis in the provenance study of ceramics that belong to three cultures that settled in the same area during various prehistoric periods. Portable energy-dispersive X-ray fluorescence spectrometry (pEDXRF) was used to determine the elemental composition of the ceramic material. The ceramic material was prepared in two different ways. The ceramic body material was ground into powder, homogenized, and then pressed into tablets. After that, the same fragments are polished in suitable places. Quantitative and qualitative analyses were performed on the tablets and polished pieces. The results were subjected to both unsupervised and supervised multivariate analysis. Based on the results, it was concluded that qualitative analysis of the well-prepared shards’ surface using EDXRF spectrometry could be utilized in provenance studies, even when the ceramic assemblages were made of similar raw materials
Effect of plasma treatment on surface chemistry and morphology of jute fibers
No full textIn this work, jute fibers, in the form of fabrics, were subjected to atmospheric pressure
dielectric barrier discharge (DBD) under different conditions (150 Hz or 300 Hz, air as working
gas, constant time of 120 s) to tailor their surface chemistry and morphology and consequently
properties. The effect of DBD treatment on the surface chemistry of jute fibers was
investigated by ATR-FTIR, XPS, and electrokinetic measurements, while FE-SEM and AFM were
used to assess the changes in the surface morphology of treated fibers. The electrokinetic
measurements and sorption properties monitored by wetting time and capillary height
measurements were used to follow aging processes in DBD-treated jute fibers. Changes in the
jute fiber surface chemistry, such as more exposed cellulose on the fiber surface due to the
removal of surface impurities and non-cellulosic components, decreased lignin and
hemicellulose contents, in parallel with cellulose oxidation, and morphology (about 3.2 times
higher average roughness, i.e., formation of new pores and capillaries as a result of the
intensive etching and ablation of the fiber surface layers) were more pronounced in the case of
lower frequency DBD treatment. The obtained results also revealed that both DBD treatments
improved the wettability of jute fibers, with lower frequency DBD treatment being more
efficient. This investigation confirmed the significant influence of aging effects in jute fibers’
functionalization using plasma
Influence of SiO2 Nanoparticles Extracted from Biomass on the Properties of Electrodeposited Ni Matrix Composite Films on Si(100) Substrate
No full textLab-made biosilica (SiO2) nanoparticles were obtained from waste biomass (rice husks) and used as eco-friendly fillers in the production of nickel matrix composite films via the co-electrodeposition technique. The produced biosilica nanoparticles were characterized using XRD, FTIR, and FE-SEM/EDS. Amorphous nano-sized biosilica particles with a high SiO2 content were obtained. Various current regimes of electrodeposition, such as direct current (DC), pulsating current (PC), and reversing current (RC) regimes, were applied for the fabrication of Ni and Ni/SiO2 films from a sulfamate electrolyte. Ni films electrodeposited with or without 1.0 wt.% biosilica nanoparticles in the electrolyte were characterized using FE-SEM/EDS (morphology/elemental analyses, roundness), AFM (roughness), Vickers microindentation (microhardness), and sheet resistance. Due to the incorporation of SiO2 nanoparticles, the Ni/SiO2 films were coarser than those obtained from the pure sulfamate electrolyte. The addition of SiO2 to the sulfamate electrolyte also caused an increase in the roughness and electrical conductivity of the Ni films. The surface roughness values of the Ni/SiO2 films were approximately 44.0%, 48.8%, and 68.3% larger than those obtained for the pure Ni films produced using the DC, PC, and RC regimes, respectively. The microhardness of the Ni and Ni/SiO2 films was assessed using the Chen-Gao (C-G) composite hardness model, and it was shown that the obtained Ni/SiO2 films had a higher hardness than the pure Ni films. Depending on the applied electrodeposition regime, the hardness of the Ni films increased from 29.1% for the Ni/SiO2 films obtained using the PC regime to 95.5% for those obtained using the RC regime, reaching the maximal value of 6.880 GPa for the Ni/SiO2 films produced using the RC regime
ATMOSPHERIC PRESSURE PLASMA IN PROCESSING OF CELLULOSE FIBERS: FROM SURFACE CLEANING TO TAILORED PROPERTIES
No full textPlasma processing of textile materials, especially ones from cellulose (natural
and man-made (or regenerated) cellulose fibers), has been the focus of many researchers in
the past three decades (Shishoo 2007, Ul Islam & Haji 2024). Plasma treatments, as an
alternative to conventional wet treatments in textile processing used to clean fiber surfaces
or to tailor fiber surface chemistry and morphology, have many advantages, such are small
energy consumption, short time of treatment, and small chemical consumption, which
makes this process environmentally friendly. Among many different plasma configurations
available, which can be classified according to several criteria, such as the type of energy
supply (direct or alternating with different frequencies), temperature (hot (thermal) and cold
(non-thermal) plasma), and pressure (low-pressure and atmospheric pressure plasma),
atmospheric pressure plasma, especially dielectric barrier discharge (DBD), is highly
promising for textile material modification thanks to its simple arrangements and
adaptability of electrodes' shape, more homogeneous surface discharge with lower
temperature electrons preventing localized overheating and damage of treated material as
well as its potential for up-scaling and implementation in existing industrial facilities and
continuous processes. In this paper, we present a comparative study on the functionalization
of cellulose fibers by DBD treatment with special emphasis on the aging effect as an
additional treatment parameter. By controlling the DBD variables, such as the nature of gas
(air, oxygen, and nitrogen), discharge power, frequency, and exposure time, a great variety
of surface effects can be achieved, such as surface cleaning and etching, introduction of
new functional groups, increase or decrease surface energy, cross-linking, etc