Search

A sustainable low-cost activated carbon substitute was produced based on pretreated lignocellulosic biomass, especially spruce sawdust. A harmful liquid waste, desalination brine, was used for the treatment of a solid wood industry waste, spruce sawdust. This approach is in the circular economy theory and aims at the decarbonization of the economy. Pretreated sawdust was tested as an adsorbent appropriate for the removal of a commonly used pollutant, methylene blue, from industrial wastewater. The adsorption capacity of the pretreated material was found to have increased four times compared to the untreated one in the case that the Freundlich equation was fitted to the isotherms' data, i.e., the one with the best fit to the isotherm's experimental data of the three isotherm models used herein. The treatment experimental conditions with desalination brine that gave maximum adsorption capacity correspond to a 1.97 combined severity factor in logarithmic form value. Moreover, a kinetic experiment was carried out with regard to the methylene blue adsorption process. The desalination brine-pretreated sawdust adsorption capacity increased approximately two times compared to the untreated one, in the case when the second-order kinetic equation was used, which had the best fit of the kinetic data of the three kinetic models used herein. In this case, the pretreatment experimental conditions that gave maximum adsorption capacity correspond to −1.049 combined severity factor in logarithmic form. Industrial scale applications can be based on the kinetic data findings, i.e., spruce sawdust optimal pretreatment conditions at 200 °C, for 25 min, with brine solution containing 98.12 g L−1 NaCl, as they are related to a much shorter adsorption period compared to the isotherm data. [ABSTRACT FROM AUTHOR]

CuFeS2 is a prominent chalcogenide that possesses similar optical properties and a significantly lower cost, compared to gold. Additionally, covalent organic frameworks are a class of materials at the forefront of current research, mainly used as photoactive components and porous absorbers. Hence, in this work, hydrophilic CuFeS2 particles are coupled with multi-functional covalent organic frameworks through ionic bonding to produce a hybrid material with unique and optimized properties. To render the CuFeS2 particles negatively charged and dispersible in water, we coated them with sodium dodecyl sulfonate, shifting the surface plasmon resonance of the nanoparticles from 472 to 492 nm. When they are electrostatically assembled with the positively charged COFs, an S-scheme is formed and the fluorescence of the hybrid materials is highly quenched, with the electron transfer happening from the networks to the nanoparticles and a simultaneous energy exchange which is dependent on the emission wavelength. Through detailed fluorescence spectroscopy, time-resolved measurements and Stern–Volmer analysis, we identified an efficient emission quenching that differs from the bulk to the exfoliated hybrid system, while detailed electron microscopy studies demonstrated the strong interaction between the two components. The quenching mechanisms and the on or off surface resonance dependent lifetime could be applied to photocatalytic and photovoltaic applications. [ABSTRACT FROM AUTHOR]

Non-toxic carbon-based hybrid nanomaterials based on carbon nanodisks were synthesized and assessed as novel antibacterial agents. Specifically, acid-treated carbon nanodisks (oxCNDs), as a safe alternative material to graphene oxide, interacted through covalent and non-covalent bonding with guanidinylated hyperbranched polyethyleneimine derivatives (GPEI5K and GPEI25K), affording the oxCNDs@GPEI5K and oxCNDs@GPEI25K hybrids. Their physico-chemical characterization confirmed the successful and homogenous attachment of GPEIs on the surface of oxCNDs, which, due to the presence of guanidinium groups, offered them improved aqueous stability. Moreover, the antibacterial activity of oxCNDs@GPEIs was evaluated against Gram-negative E. coli and Gram-positive S. aureus bacteria. It was found that both hybrids exhibited enhanced antibacterial activity, with oxCNDs@GPEI5K being more active than oxCNDs@GPEI25K. Their MIC and MBC values were found to be much lower than those of oxCNDs, revealing that the GPEI attachment endowed the hybrids with enhanced antibacterial properties. These improved properties were attributed to the polycationic character of the oxCNDs@GPEIs, which enables effective interaction with the bacterial cytoplasmic membrane and cell walls, leading to cell envelope damage, and eventually cell lysis. Finally, oxCNDs@GPEIs showed minimal cytotoxicity on mammalian cells, indicating that these hybrid nanomaterials have great potential to be used as safe and efficient antibacterial agents. [ABSTRACT FROM AUTHOR]

In this study, 3-dimensional molybdenum disulfide (MoS2) structures, integrated with hematite (α-Fe2O3) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS2 flakes, resembling spherical flower-like morphology, and the nanoparticulate α-Fe2O3 structures decorate the 3D network. By raising the α-Fe2O3 weight ratio, the composites' specific surface area and morphology were not affected, regardless of the partial cover of the cavities for higher hematite content. Moreover, the crystallinity examination with XRD, Raman, and FTIR techniques revealed that the precursor reagents were fully transformed to well-crystalized MoS2 and Fe2O3 composites of high purity, as no organic or inorganic residues could be detected. The photocatalytic oxidation and reduction performance of these composites was evaluated against the tetracycline pharmaceutical and the industrial pollutant hexavalent chromium, respectively. The improvement in the removal efficiencies demonstrates that the superior photoactivity originates from the high crystallinity and homogeneity of the composite, in combination with the enhanced charge carriers' separation in the semiconductors' interface. [ABSTRACT FROM AUTHOR]

The present work focuses on TiO2 modification with carbon dots (CDs) using a hydrothermal process, which results in the synthesis of CD/TiO2 nanocomposite photocatalysts characterized by exceptional optoelectronic properties. The structural and physicochemical properties of the obtained nanocomposites, which contained varying amounts of CDs, were precisely assessed. HR-TEM analysis showed that the prepared nanocomposites consisted of rod-shaped TiO2 nanoparticles and CDs well-dispersed on their surface. The optical properties of the nanocomposites were studied using UV–vis diffuse reflectance spectroscopy. All CD/TiO2 samples presented decreased energy gap values compared with bare TiO2 samples; the band gap was further decreased as the CD concentration rose. Electrochemical measurements revealed that the presence of CDs improved the photocurrent response of the TiO2, presumably due to enhanced charge separation and decreased recombination. The synthesized nanomaterials were used as photocatalysts to produce hydrogen via the photoreforming of ethanol and glycerol green organic compounds, under 1-sun illumination. The photocatalytic experiments confirmed that the optimum loading of CDs corresponded to a percentage of 3% (w/w). Ethanol photoreforming led to a H2 production rate of 1.7 μmol∙min−1, while in the case of the glycerol sacrificial agent, the corresponding rate was determined to be 1.1 μmol∙min−1. The recyclability study revealed that the photocatalyst exhibited consistent stability during its reuse for hydrogen production in the presence of both ethanol and glycerol. [ABSTRACT FROM AUTHOR]

The effect of carbon dots (CDs) on a model blayer membrane was studied as a means of comprehending their ability to affect cell membranes. Initially, the interaction of N-doped carbon dots with a biophysical liposomal cell membrane model was investigated by dynamic light scattering, z-potential, temperature-modulated differential scanning calorimetry, and membrane permeability. CDs with a slightly positive charge interacted with the surface of the negative-charged liposomes and evidence indicated that the association of CDs with the membrane affects the structural and thermodynamic properties of the bilayer; most importantly, it enhances the bilayer's permeability against doxorubicin, a well-known anticancer drug. The results, like those of similar studies that surveyed the interaction of proteins with lipid membranes, suggest that carbon dots are partially embedded in the bilayer. In vitro experiments employing breast cancer cell lines and human healthy dermal cells corroborated the findings, as it was shown that the presence of CDs in the culture medium selectively enhanced cell internalization of doxorubicin and, subsequently, increased its cytotoxicity, acting as a drug sensitizer. [ABSTRACT FROM AUTHOR]

Homojunction engineering has emerged as a potent strategy to evade interfacial stability issues and improve the efficiency of nanostructured metal oxide photocatalysts, though rarely combined with the enhanced light capture ability of three-dimensional macroporous photonic crystal structures. Herein, the formation of nanoscale n-n+ homojunctions between different Mo- and Ca-doped BiVO4 nanocrystals in the skeleton of photonic band gap (PBG) engineered inverse opals is introduced as an advanced approach to simultaneously promote visible light harvesting, electron transport, and charge separation of BiVO4 nanomaterials for the photoelectrocatalytic degradation of pharmaceutical contaminants of emerging concern. Controlled deposition of BiVO4 inverse opal films with tailored PBGs was combined with compositional tuning by Mo- and Ca-doping for slow-photon-assisted visible-light-activated (VLA) photocatalysis. The introduction of shallow dopant states in the Mo-, Ca-doped BiVO4 nanoparticles with relatively weak structural distortions but significantly different donor concentrations resulted in a broad distribution of type-II homojunctions in the nanocrystalline inverse opal walls. Comparative photoelectrochemical evaluation showed that nanostructured homojunction Mo-BiVO4/Ca-BiVO4 photonic films largely outperformed their individual constituents in both photocurrent generation and the VLA photocatalytic degradation rate. Moreover, they exhibited markedly improved performance in the photoelectrocatalytic degradation of tetracycline and ciprofloxacin broad-spectrum antibiotics as well as salicylic acid under visible light, validating their application potential in VLA water remediation by pharmaceutical micropollutants. [ABSTRACT FROM AUTHOR]

Following the long-standing use of the liquid exfoliation of graphite for the production of graphene, a number of analogous van der Waals 2D nanomaterials have been also produced and studied extensively for several applications. Recently, liquid exfoliation has also been applied to isolate non-van der Waals 2D nanostructures. Here, we describe a green procedure for the liquid exfoliation of natural hematite and magnetite – natural iron ores – obtained from the Greek territory. Natural iron ores were exfoliated in a solution of melamine in water under mild sonication. The ultrathin exfoliated nanoplatelets, hematene and magnetene, respectively, form stable dispersions in pure water and have been extensively characterized by spectroscopic and microscopic techniques. Optical limiting experiments reveal the efficiency of the present non-van der Waals 2D nanomaterials, rendering them highly attractive for several applications in opto-electronics and photonics. [ABSTRACT FROM AUTHOR]

The synthesis of titania-based composite materials with anticancer potential under visible-light irradiation is the aim of this study. In specific, titanium dioxide (TiO2) nanoparticles (NPs) chemically modified with silver were embedded in a stimuli-responsive microgel (a crosslinked interpenetrating network (IP) network that was synthesized by poly (N-Isopropylacrylamide) and linear chains of polyacrylic acid sodium salt, forming composite particles. The ultimate goal of this research, and for our future plans, is to develop a drug-delivery system that uses optical fibers that could efficiently photoactivate NPs, targeting cancer cells. The produced Ag-TiO2 NPs, the microgel and the composite materials were characterized through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), micro-Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). Our results indicated that Ag-TiO2 NPs were successfully embedded within the thermoresponsive microgel. Either Ag-TiO2 NPs or the composite materials exhibited high photocatalytic degradation efficiency on the pollutant rhodamine B and significant anticancer potential under visible-light irradiation. [ABSTRACT FROM AUTHOR]

In the reaction of zinc(II) sulfate and the chloride salt of 2-acetylpyridine-aminoguanidine, two types of complex were obtained, i.e., [Zn(H2O)6](H2L)2(SO4)3·3H2O and [Zn(L)H2O(SO4)]·H2O, depending on the presence of LiOAc as the deprotonating agent. The physicochemical, structural, and photoluminescence properties of the complexes were examined. In the first complex, obtained in the absence of LiOAc, the Schiff base had the role of a counter-ion in its doubly protonated form, while in the presence of LiOAc, upon deprotonation, coordination takes place, and thus the Schiff base acts as a tridentate N3 ligand. In the latter complex, the ligand is coordinated through pyridine, azomethine, and the imino nitrogen of the aminoguanidine residue, leading to formation of two fused five-membered chelate rings. Both the examined complexes, as well as the ligand itself, show high photoluminescence. [ABSTRACT FROM AUTHOR]

To meet current economic demands enforcing the replacement of platinum-group metals, extensively used in three-way-catalytic converters (TWC), research is driven towards low-cost and widely available base metals. However, to cope with their lower activity, high metal loadings must be coupled with increased dispersion. Herein, a series of CuO/Al2O3 samples is produced and the effect of different alumina supports' properties on CuO dispersion, speciation and eventually on the TWC performance is studied. The alumina samples are synthesized via different methods, including soft-templating routes and flame spray pyrolysis, and compared with a commercial one, while CuO used as the catalytic active phase is added through ammonia-driven deposition–precipitation. As found, the large surface area and low crystallinity of the aluminas produced by soft-templating routes favor strong metal–support interaction, generating highly dispersed and strongly bonded CuO species at low loading and copper-aluminate phases at high loading. Notably, the use of amorphous mesoporous alumina completely prevents the formation of crystalline CuO even at 15 wt% Cu. Such high metal loading and dispersion capacity without the application of elevated calcination temperatures is one of the best reported for nonreducible supports. Catalytic evaluation of this material reveals a pronounced enhancement of oxidation activity with metal loading increase. [ABSTRACT FROM AUTHOR]

Adjusting the synthetic route to control the shape, composition, and crystal structure of nanostructured topological insulators (TIs) is a challenge in the realization of TI systems with specific functionalities. Here, we report probing the multiphasic evolution of Bi2Te3 nanoplatelets primarily using microscopic, elemental and crystallographic methods. An evolution model is proposed along which the nanoplatelets undergo compositional and morphological changes. These changes have a pronounced impact on the electronic and thermoelectric properties of the initial, intermediate, and final stages of the model. The materials are synthesized via a solvothermal method, which, depending on the control of the precursors' relative concentrations, leads to multiphasic materials ranging from stoichiometric Bi2Te3 nanoplatelets to Bi4Te3 and BiTe. A twin plane model appears to explain adequately the successive formation of different Bi-rich phases, allowing control of the morphological and electronic properties of the yield. Specifically, the initial formation of Bi-rich triangular nanoplatelets triggers the generation of additional twin planes and subsequently leads to the ultimate 2D growth of hexagonal bismuth telluride nanoplatelets. The findings of this study pave the way towards engineering novel nanostructured Bi−Te topological compounds with tailored properties. [ABSTRACT FROM AUTHOR]

We present a simple, efficient method, which combines uniaxial compression and subsequent poling, to produce piezoelectric polyvinylidene fluoride-based epoxy composites. The values of the piezoelectric factors obtained are slightly higher than those of neat piezoelectric polyvinylidene fluoride. The composites respond rapidly and reach a saturation voltage output, to the application of mechanical stimulus quickly. The composites are promising for the creation of "bulk" piezoelectric devices, different from the usual stretched films, exploiting the physico-chemical a of the epoxy matrix. The piezoelectric factor d31 vs the mechanical stimulus for the specimens studied scale according to a double logarithmic representation. [ABSTRACT FROM AUTHOR]

Broadband dielectric spectroscopy measurements of polyaniline/graphene oxide composites were conducted for an as-prepared and a thermally annealed specimen, respectively, from 15 K to room temperature. The electrical conductivity values of the annealed composite display a very modest rise denoting the important contributions of the graphene oxide component to achieving electrical stability of the polymer. Patterns of the dc conductivity as a function of temperature also reveal a metal to insulator transition at around 75 K. The transition is dominated by two key factors: temperature and annealing process. Metal-like and insulating features are subsequently detected, as well, and accordingly described to provide a qualitative inspection of the charge transfer mechanisms involved. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) were incorporated into the active layer of mesoporous TiO2 films resulting in MWCNTs-TiO2 nanocomposites with improved electrical conductivity. These MWCNTs-TiO2 nanocomposite films were prepared by a direct mixing method and the “doctor blade” technique. The films were sintered at various annealing temperatures (300, 350, 400, and 450 °C) in order to examine the effect of annealing temperature to the morphology and electrochemical activity of the films. The presence of anatase TiO2 and MWCNTs has been confirmed by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, while conductivity and electrochemical properties of the nanocomposite MWCNΤs-TiO2 films were examined via cyclic voltammetry (CV) and spectroelectrochemistry. After successful protein immobilization (Cyt-c), the electrochemical and spectroelectrochemical behavior of these hybrid electrodes (Cyt-c/MWCNTs-TiO2) was examined in detail and particularly the effect of MWCNTs on the interfacial electron transfer between the film electrode and the adsorbed protein molecules.Schematic illustration of MWCNTs-TiO2 nanocomposite films used for Cyt-c immobilization. [ABSTRACT FROM AUTHOR]

Tailoring metal oxide photocatalysts in the form of heterostructured photonic crystals has spurred particular interest as an advanced route to simultaneously improve harnessing of solar light and charge separation relying on the combined effect of light trapping by macroporous periodic structures and compositional materials' modifications. In this work, surface deposition of FeOx nanoclusters on TiO2 photonic crystals is investigated to explore the interplay of slow-photon amplification, visible light absorption, and charge separation in FeOx–TiO2 photocatalytic films. Photonic bandgap engineered TiO2 inverse opals deposited by the convective evaporation-induced co-assembly method were surface modified by successive chemisorption-calcination cycles using Fe(III) acetylacetonate, which allowed the controlled variation of FeOx loading on the photonic films. Low amounts of FeOx nanoclusters on the TiO2 inverse opals resulted in diameter-selective improvements of photocatalytic performance on salicylic acid degradation and photocurrent density under visible light, surpassing similarly modified P25 films. The observed enhancement was related to the combination of optimal light trapping and charge separation induced by the FeOx–TiO2 interfacial coupling. However, an increase of the FeOx loading resulted in severe performance deterioration, particularly prominent under UV-Vis light, attributed to persistent surface recombination via diverse defect d-states. [ABSTRACT FROM AUTHOR]

Aiming to understand and enhance the capacity of carbon dots (CDs) to transport through cell membranes and target subcellular organelles—in particular, mitochondria—a series of nitrogen-doped CDs were prepared by the one-step microwave-assisted pyrolysis of citric acid and ethylenediamine. Following optimization of the reaction conditions for maximum fluorescence, functionalization at various degrees with alkylated triphenylphosphonium functional groups of two different alkyl chain lengths afforded a series of functionalized CDs that exhibited either lysosome or mitochondria subcellular localization. Further functionalization with rhodamine B enabled enhanced fluorescence imaging capabilities in the visible spectrum and allowed the use of low quantities of CDs in relevant experiments. It was thus possible, by the appropriate selection of the alkyl chain length and degree of functionalization, to attain successful mitochondrial targeting, while preserving non-toxicity and biocompatibility. In vitro cell experiments performed on normal as well as cancer cell lines proved their non-cytotoxic character and imaging potential, even at very low concentrations, by fluorescence microscopy. Precise targeting of mitochondria is feasible with carefully designed CDs that, furthermore, are specifically internalized in cells and cell mitochondria of high transmembrane potential and thus exhibit selective uptake in malignant cells compared to normal cells. [ABSTRACT FROM AUTHOR]

In this paper we report a low cost, simple, electrochemical method for large-area growth of single crystal ZnO nanorods. The method utilizes a metallic zinc foil as the source of the necessary zinc ions for ZnO growth on indium-doped tin oxide (ITO) glass slides. The method is thoroughly discussed and investigated varying all the parameters involved. The resulting ZnO nanorods are highly oriented along c-axis and densely packed, while their length and diameter can be tuned by varying the growth parameters. Two different types of seed layers on the ITO glass slides are tested. A seed layer made by spin coating of ZnO nanoparticles results in a twofold increase of the ZnO nanorod surface density as compared with a ZnO thin film seed layer by physical vapor deposition. Additionally, the effect of oxygen supply during electrodeposition was investigated as a crucial regulatory parameter not only for the geometrical and topological characteristics of the ZnO nano-arrays but for their physical properties as well. [ABSTRACT FROM AUTHOR]

An efficient doxorubicin (DOX) drug delivery system with specificity against tumor cells was developed, based on multi-walled carbon nanotubes (MWCNTs) functionalized with guanidinylated dendritic molecular transporters. Acid-treated MWCNTs (oxCNTs) interacted both electrostatically and through hydrogen bonding and van der Waals attraction forces with guanidinylated derivatives of 5000 and 25,000 Da molecular weight hyperbranched polyethyleneimine (GPEI5K and GPEI25K). Chemical characterization of these GPEI-functionalized oxCNTs revealed successful decoration with GPEIs all over the oxCNTs sidewalls, which, due to the presence of guanidinium groups, gave them aqueous compatibility and, thus, exceptional colloidal stability. These GPEI-functionalized CNTs were subsequently loaded with DOX for selective anticancer activity, yielding systems of high DOX loading, up to 99.5% encapsulation efficiency, while the DOX-loaded systems exhibited pH-triggered release and higher therapeutic efficacy compared to that of free DOX. Most importantly, the oxCNTs@GPEI5K-DOX system caused high and selective toxicity against cancer cells in a non-apoptotic, fast and catastrophic manner that cancer cells cannot recover from. Therefore, the oxCNTs@GPEI5K nanocarrier was found to be a potent and efficient nanoscale DOX delivery system, exhibiting high selectivity against cancerous cells, thus constituting a promising candidate for cancer therapy. [ABSTRACT FROM AUTHOR]

Photonic crystal structuring has emerged as an advanced method to enhance solar light harvesting by metal oxide photocatalysts along with rational compositional modifications of the materials' properties. In this work, surface functionalization of TiO2 photonic crystals by blue luminescent graphene quantum dots (GQDs), n–π* band at ca. 350 nm, is demonstrated as a facile, environmental benign method to promote photocatalytic activity by the combination of slow photon-assisted light trapping with GQD-TiO2 interfacial electron transfer. TiO2 inverse opal films fabricated by the co-assembly of polymer colloidal spheres with a hydrolyzed titania precursor were post-modified by impregnation in aqueous GQDs suspension without any structural distortion. Photonic band gap engineering by varying the inverse opal macropore size resulted in selective performance enhancement for both salicylic acid photocatalytic degradation and photocurrent generation under UV–VIS and visible light, when red-edge slow photons overlapped with the composite's absorption edge, whereas stop band reflection was attenuated by the strong UVA absorbance of the GQD-TiO2 photonic films. Photoelectrochemical and photoluminescence measurements indicated that the observed improvement, which surpassed similarly modified benchmark mesoporous P25 TiO2 films, was further assisted by GQDs electron acceptor action and visible light activation to a lesser extent, leading to highly efficient photocatalytic films. [ABSTRACT FROM AUTHOR]

Heterostructured bilayer films, consisting of co-assembled TiO2 photonic crystals as the bottom layer and a highly performing mesoporous P25 titania as the top layer decorated with CoOx nanoclusters, are demonstrated as highly efficient visible-light photocatalysts. Broadband visible-light activation of the bilayer films was implemented by the surface modification of both titania layers with nanoscale clusters of Co oxides relying on the chemisorption of Co acetylacetonate complexes on TiO2, followed by post-calcination. Tuning the slow photon regions of the inverse opal supporting layer to the visible-light absorption of surface CoOx oxides resulted in significant amplification of salicylic-acid photodegradation under visible and ultraviolet (UV)–visible light (Vis), outperforming benchmark P25 films of higher titania loading. This enhancement was related to the spatially separated contributions of slow photon propagation in the inverse opal support layer assisted by Bragg reflection toward the CoOx-modified mesoporous P25 top layer. This effect indicates that photonic crystals may be highly effective as both photocatalytically active and backscattering layers in multilayer photocatalytic films. [ABSTRACT FROM AUTHOR]

Oxidized multi-walled carbon nanotubes (oxCNTs) were functionalized by a simple non-covalent modification procedure using quaternized hyperbranched poly(ethyleneimine) derivatives (QPEIs), with various quaternization degrees. Structural characterization of these hybrids using a variety of techniques, revealed the successful and homogenous anchoring of QPEIs on the oxCNTs' surface. Moreover, these hybrids efficiently dispersed in aqueous media, forming dispersions with excellent aqueous stability for over 12 months. Their cytotoxicity effect was investigated on two types of gram(−) bacteria, an autotrophic (cyanobacterium Synechococcus sp. PCC 7942) and a heterotrophic (bacterium Escherichia coli). An enhanced, dose-dependent antibacterial and anti-cyanobacterial activity against both tested organisms was observed, increasing with the quaternization degree. Remarkably, in the photosynthetic bacteria it was shown that the hybrid materials affect their photosynthetic apparatus by selective inhibition of the Photosystem-I electron transport activity. Cytotoxicity studies on a human prostate carcinoma DU145 cell line and 3T3 mouse fibroblasts revealed that all hybrids exhibit high cytocompatibility in the concentration range, in which they also exhibit both high antibacterial and anti-cyanobacterial activity. Thus, QPEI-functionalized oxCNTs can be very attractive candidates as antibacterial and anti-cyanobacterial agents that can be used for potential applications in the disinfection industry, as well as for the control of harmful cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

In the present study, the possibility of improving the higher heating value (HHV) of lignocellulosic biomass, especially barley straw, was examined. The research deals with the treatment of barley straw by acid-catalyzed wet torrefaction (ACWT), also called acid hydrolysis, in a batch reactor (autoclave) Parr 4553 3.75 L. In this case, two different simulation approaches were applied: (i) combined severity factor (CSF) and (ii) response surface methodology (RSM) based on Box–Behnken design of experiments (DoE). Sulfuric acid (SA) concentration, temperature and time were the ACWT parameters examined herein. An oxygen bomb calorimeter was used for the HHV measurement. The findings indicated that the composition changes of the straw due to ACWT had a significant effect on the HHV of the pretreated material. In this study, treatment conditions were 10–35 mM SA, 160–200 °C and an isothermal reaction time 0–40 min (preheating period not included in these values). In conclusion, there was a significant increase in the HHV up to 24.3 MJ/kg for the ACWT barley straw, compared to 17.5 MJ/kg for the untreated straw, at optimal conditions of 200 °C for 25 min (isothermal period) and 35 mM SA. This resulted in a 1.39 enhancement factor (EF) and 68% energy yield (EY). [ABSTRACT FROM AUTHOR]