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Halogen Bonding: A Pathway to More Stable Perovskite Solar Cells
No full textHybrid metal halide perovskites have shown potential in photovoltaics over the last decade [1,2].
Despite high solar-to-electric power conversion efficiencies and excellent optoelectronic
properties, these materials are hindered by stability issues caused by operating conditions [3].
One of the leading sources of instabilities occurs at the interfaces with the charge transport layers
and is caused by ion migration [2]. There have been efforts to address this by relying on interfacial
engineering, such as using supramolecular modulators featuring halogen bonding (XB) [4]. Metal
oxides, as the most frequently used charge-transport layers for hybrid perovskite solar cells, are
suitable for XB as a way to improve operational stability [3]. XB can affect hydrophobicity, ion
migration, and charge transfer, affecting the resulting photovoltaic characteristics [5]. We
applied 1,4-diiodotetrafluorobenzene (TFDIB) as an XB agent at the interface of TiO2 in
perovskite solar cells [6]. We investigate structural and optoelectronic characteristics by a
combination of techniques, including scanning electron microscopy, X-ray diffraction, UV-vis
absorption, photoluminescence spectroscopy, X-ray and ultraviolet photoelectron spectroscopy,
to identify interfacial changes upon XB modulation [6]. As a result, we demonstrate the improvement of operational stability in perovskite solar cells, providing a versatile supramolecular
strategy in hybrid photovoltaics
Novel alginate/activated-charcoal platform for local treatment of resistant pathogens in wounds
No full textAntibiotic resistance is one of the biggest threats to global health, food security, and development
today [1] and new strategies to address this clinical problem are urgently needed. The aim of this work was to produce
novel composites based on either Ca- or Zn-alginate hydrogels and activated charcoal (AC) particles that would, upon
contact with physiological fluids, continuously release at least one bioactive agent directly into the wound area. In
addition, AC particles served as carriers of other active substances such as povidone iodine (PVP-I), a very powerful
antiseptic, which was used as a model substance.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Poboljšanje metode merenja mehaničkih svojstava teksturirani filament/elastan hibridnih pređa
No full textThe mechanical properties of hybrid yarns containing elastomeric
component are rather difficult to measure. A standard approach to measuring tenacity and
elongation cannot be applied to this type of yarn. The main reason is the high elasticity of
both elastane and textured filaments. An attempt was made in this study to solve the
problem by measuring the mechanical properties of textured filament/elastane hybrid
yarns under pretension force which is higher than standard ones. Several pretension forces
were applied: 1.5 cN, 4.5 cN, 7.5 cN, 10.5 cN and 13.5 cN. Textured polyamide 6.6 was
used as a spirally covering filament, while the core yarn was LYCRA® elastomeric yarn
with various linear densities. The results indicated that with an increase in the pretension
force, the elongation of the polyamide/ LYCRA® hybrid yarns decreased whereas, the
pretension forces had little effect on the tenacity values for investigated samples. These
preliminary results are promising, however, the method must be further developed to be
ultimately applicable to all complex yarns containing elastomer filament.Merenje mehaničkih svojstava hibridnih pređa koje sadrže elastansku
komponentu vrlo je komplikovano. Standardni pristup merenju prekidne jačine i
istegljivosti ne može se primeniti na ovaj tip pređa. Glavni razlog je velika elastičnost kako
elastanskih, tako i teksturiranih filamenata. U okviru ovog istraživanja, rešavanju
navedenog problema se pristupilo merenjem mehaničkih svojstava teksturirani
filament/elastan hibridnih pređa uz prednaprezanje veće od standardnih vrednosti. U
ovom radu je primenjeno nekoliko različitih sila predzatezanja: 1,5 cN, 4,5 cN, 7,5 cN,
10,5 cN, i 13,5 cN. Kao spiralno omotavajući filament korišćen je tekstirirani poliamid 6.6,
a za jezgro hibridne pređe upotrebljene su Lycra® elastomerne pređe različitih finoća.
Rezultati su pokazali da se sa povećanjem sile predzatezanja, izuduženje poliamid/Lycra® hibridnih pređa smanjuje, uz slabo izražen uticaj sile predzatezanja na vrednosti prekidne
jačine ispitivanih hibridnih pređa. Ovakvi rezultati su obećavajući, međutim, metoda se
mora dalje razvijati da bi bila generalno primenjiva na sve složene pređe koje sadrže
elastanski filamen
Antibacterial Activity of Multifunctional Alginate-Based Composite
No full textAntibacterial resistance is one of the most significant public health problems
today. In order to address this serious issue, antibacterial activity of novel
biomaterials should not be based on antibiotics but on other antimicrobial
substances. Povidone iodine (PVP-I) is a powerful antiseptic used in medicine for
very long time with no documented microbial resistance up to now. However,
systemic iodine absorption was often reported after its prolonged medical usage.
The aim of this work was to produce novel composite biomaterial based on
immobilized PVP-I onto activated charcoal (AC) particles and Ca-alginate
hydrogel. The composite was characterized regarding iodine adsorption and
desorption from AC particles as well as composite morphology, textural
parameters and AC release profile. Antibacterial activity was comprehensively
investigated in vitro against wide range of gram-positive and gram-negative
resistant bacteria. It was shown that immobilized PVP-I is firmly adsorbed on AC
particles and that its release in the surrounding medium is negligible which is
very important in regards of preventing iodine systemic absorption. In addition,
the obtained composite has exhibited excellent antibacterial activity against all
tested microorganisms. This novel composite enables further development of
efficient antibacterial wound dressings based on immobilized PVP-I for local
wound application
Friction in soft biological systems and surface self-organization: the role of viscoelasticity
No full textFriction is a critical factor in the proper functioning of human organs as well as in the potential development of disease. It is also important for the design of diagnostic and interventional medical devices. Nanoscale surface roughness, viscoelastic or plastic deformations, wear, and lubrication all influence the functions of individual cells. The effects of friction in soft matter systems are quantified using different types of frictional coefficients, including the dynamic friction coefficient, friction-skin drag, and pressure drag. These coefficients are determined by the viscoelastic properties of the two systems in contact and their relative velocity. In this review, several biological systems are considered, including (i) epithelial tissues in contact with soft hydrogel-like implants, (ii) the collective migration of epithelial monolayers on substrate matrices, (iii) blood flow through blood vessels, and (iv) the movement of cancer cells past epithelial clusters along with the migration of epithelial cells within the cluster
Electrochemical polymerization of pyrrole on mild steel from p-toluensulfonic acid electrolyte
No full textConditions for electrochemical synthesis of polypyrrole on mild steel were investigated in an aqueous
electrolyte containing different concentrations of p-toluenesulfonic acid in the range of 0.05 - 0.3 mol
dm-3 without and with the addition of 0.2 mol dm-3
pyrrole, aiming to estimate the composition of the
electrolyte and polymerization current density, necessary for achieving the formation of uniforme
and adherent polypyrrole. The optimal concentration of p-toluensulfonic acid of 0.1 mol dm-3
,was
chosen based on recorded anodic polarization curves. To estimate the current density for the
electrochemical polymerization of pyrrole, chronopotentiometric curves of mild steel at different
constat current densities, were recorded in 0.1 mol dm-3
p-toluenesulfonic acid and 0.2 mol dm -3
pyrrole. It was shown that deposition of polypyrrole was achieved with an induction period which
was lower comparing to the resuts obtained in oxalic acid, as the most popular electrolyte for
electrochemical synthesis of polypyrrole on steel. The protection efficiency based on polarization
curves of mild steel and mild steel with electrochemically formed p-toluensulfonic acid doped
polypyrrole in 3% NaCl was around oko 90 % which is higher than the value obtained for ptoluensulfonic acid doped polyaniline
Expanded Perlite-Reinforced Alginate Xerogels: A Chemical Approach to Sustainable Building and Packaging Materials
No full textIn sustainable construction and packaging, the development of novel bio-based materials is crucial, driving a re-evaluation of traditional components. Lightweight, biodegradable materials, including xerogels, have great potential in architectural and packaging applications. However, reinforcing these materials to improve their mechanical strength remains a challenge. Alginate is a promising matrix material that may be compatible with inorganic fibrous or particulate materials. In this study, biocomposite xerogel-structured foam materials based on an alginate matrix with expanded perlite reinforcement are improved using certain additives in different weight ratios. The plasticizers used include glycerol and gum arabic, while chitosan was added as an additional reinforcement, and iota carrageenan was added as a stabilizer. The tested specimens, with varying weight ratios of the added components, showed good mechanical behavior that highlights their potential use as packaging and/or architectural materials. The influence of the presence of different components in the composite material specimens on the modulus of elasticity was investigated using SEM images and FTIR analyses of the specimens. The results show that the specimen with the largest improvement in the elastic modulus contained a combination of chitosan and glycerol at a lower percentage (1.96 MPa), and the specimen with the largest improvement in tensile strength was the specimen containing chitosan with no plasticizers (120 kPa), compared to cases where combinations of other materials are present
Tehnološki postupak dobijanja ekstrakta zelenog čaja primenom ekološki prihvatljivog procesa
No full textProblemi povezani sa konvencionalnim tehnikama ekstrakcije kao što su velika potrošnja energije i rastvarača, dugo vreme ekstrakcije i ograničena selektivnost čine ih manje poželjnim u ekstrakciji prirodnih komponenti iz biljnog materijala. Pored toga, potrošnja velikih količina toksičnih organskih rastvarača u sektorima istraživačkih laboratorija i industrije može izazvati i zdravstvene i ekološke probleme. Zbog svega navedenog javlja se potreba za novim i efikasnijim pristupima koji se odnose na korišćenje održivih procesa ekstrakcije i upotrebu bezbednijih rastvarača.
Predloženo tehničko rešenje opisuje tehnološki postupak dobijanja ekstrakta zelenog čaja za primenu u proizvodnji funkcionalne hrane korišćenjem ekološki prihvatljivog procesa ekstrakcije koji se zasniva na upotrebi zelenog medijuma natkritičnog ugljenik (IV) oksida (nkCO2). Zeleni medijum se u potpunosti uklanja iz finalnog proizvoda i može se reciklirati nakon proizvodnje. Hemijska svojstva dobijenih ekstrakata kao i njihova antioksidativna aktivnost su detaljno ispitana. Ekstrakcijom pomoću nkCO2 omogućeno je selektivno izolovanje odgovarajućih grupa sekundarnih metabolita iz čaja varijacijom procesnih parametara i dobijanje ekstarkata sa visokim sadražajem ukupnih fenola, flavonoida, hlorofila A i kofeina, kao i jakom antioksidativnom aktivnošću. Dobijeni proizvodi imaju slična ili bolja svojstva od komercijalno dostupnih i dobijenih konvencionalnim tehnikama ekstrakcije, a proizvedeni su za relativno kratko vreme upotrebom zelenog rastvarača.
Predmetno tehničko rešenje nudi zamenu tehnologija koje se smatraju štetnim po zdravlje i životnu sredinu zelenim pristupom za proizvodnju ekstrakta zelenog čaja za primenu u proizvodnji funkcionalne hrani. Predloženi savremeni tehnološki proces ekstrakcije pomoću nkCO2 ima za cilj dobijanje viskoko čistih krajnjih proizvoda sa odgovarajućim hemijskim karakteristikama, koji ne sadrže organske rastvarače i ne zahtevaju dalje prečišćavanje.Tehničko rešenje kategorije M84 – Bitno poboljšano tehničko rešenje na nacionalnom nivo
Modified Cellulose-Based Waste for Enhanced Adsorption of Selected Heavy Metals from Wastewater
No full textDue to industrial growth and its impact on the environment, the increasing amount of industrial waste requires a comprehensive approach aligned with the principles of sustainable development. The main goals are not only to preserve natural resources but also to encourage innovation in the reuse of waste materials. In an attempt to reduce the problems regarding waste disposal and wastewater treatment in the textile industry, fibrous textile waste was used as a starting material to obtain carbon adsorbents for the removal of pollutants from wastewater. Waste cotton and mixed yarns, mainly consisting of polysaccharide cellulose, were hydrothermally carbonized and activated with KOH to convert them into efficient carbon adsorbents for heavy metal removal from water. Characterization of carbonized material showed that after activation, an increase in specific surface area (up to 872 m2/g) and content of surface oxygen groups (6.04 mmol/g) leads to a higher affinity towards heavy metal ions, especially lead ions, and high adsorption capacity of 19.98 mg/g obtained for activated cotton yarns. The results of this research represent a contribution to the reduction of waste materials by modifying them into adsorbents, while the regeneration of adsorbents is an example of the practical application of polysaccharide-based materials in the purification of wastewater containing various heavy metal ions
Functionalization of silk with actinomycins from Streptomyces anulatus BV365 for biomedical applications
No full textSilk, traditionally acclaimed as the “queen of fiber,” has been widely used thanks to its brilliant performance such as gentleness, smoothness and comfortableness. Owing to its mechanical characteristics and biocompatibility silk has a definitive role in biomedical applications, both as fibroin and fabric. In this work, the simultaneous dyeing and functionalization of silk fabric with pigments from Streptomyces anulatus BV365 were investigated. This strain produced high amounts of orange extracellular pigments on mannitol-soy flour agar, identified as actinomycin D, C2 and C3. The application of purified actinomycins in the dyeing of multifiber fabric was assessed. Actinomycins exhibited a high affinity towards protein fibers (silk and wool), but washing durability was maintained only with silk. Acidic condition (pH5) and high temperature (65°C) facilitated the silk dyeing. The morphologies and chemical components of the treated silk fabrics were analyzed using scanning electron microscopy and Fourier transform infrared spectroscopy. The results showed the pigments bind to the silk through interaction with the carbonyl group in silk fibroin rendering the functionalized, yet surface that does not cause skin irritation. The treated silk exhibited a remarkable antibacterial effect, while the biocompatibility test performed with 3D-reconstructed human epidermis model indicated safe biological properties, paving the way for future application of this material in medicine