Photocatalytic activity of titania–based photocatalysts doped with 1% La has been tested in UVA radiation-induced degradation of two β-blockers – metoprolol tartrate (MET) and propranolol ...hydrochloride (PRO). Photocatalysts have been synthesized by sol–gel process followed by calcination at various temperatures in the range of 450–750°C. The great impact of calcination temperature on the structural, compositional and morphological properties of prepared catalysts has been revealed by XRPD, SEM, BET and Raman scattering measurements. Doped catalysts calcined at 450–650°C, with dominant anatase phase and developed mesoporous structure, have displayed higher photocatalytic performance than much less porous samples calcined at 700–750°C, with sodium hexatitanate as dominant phase. Also, La-doped anatase sample has shown higher efficiency in degradation of MET and PRO in comparison with the efficiency of undoped TiO2 nanopowders calcined at same temperatures. The quenching effects of various scavengers suggest that the major role in degradation of MET may be attributed to reactive radicals, whereas photogenerated holes are mainly responsible for degradation of PRO. Applying density functional theory (DFT) calculations, we analyzed fundamental structural and electronic properties (total and polar surface areas, frontier molecular orbitals, optoelectronic properties and average local ionization energy surfaces) of MET and PRO molecules, which are of significance for the understanding of more effective degradation of PRO in comparison with MET.
Due to the inability of conventional wastewater treatment procedures to remove organic pharmaceutical pollutants, active pharmaceutical components remain in wastewater and even reach tap water. In ...terms of pharmaceutical pollutants, the scientific community focuses on β-blockers due to their extensive (over)usage and moderately high solubility. In this study, the photocatalytic activity of V2O5 was investigated through the degradation of nadolol (NAD), pindolol (PIN), metoprolol (MET), and their mixture under ultraviolet (UV) irradiation in water. For the preparation of V2O5, facile hydrothermal synthesis was used. The structural, morphological, and surface properties and purity of synthesized V2O5 powder were investigated by scanning electron microscopy (SEM), X-ray, and Raman spectroscopy. SEM micrographs showed hexagonal-shaped platelets with well-defined morphology of materials with diameters in the range of 10–65 µm and thickness of around a few microns. X-ray diffraction identified only one crystalline phase in the sample. The Raman scattering measurements taken on the catalyst confirmed the result of XRPD. Degradation kinetics were monitored by ultra-fast liquid chromatography with diode array detection. The results showed that in individual solutions, photocatalytic degradation of MET and NAD was relatively insignificant (<10%). However, in the PIN case, the degradation was significant (64%). In the mixture, the photodegradation efficiency of MET and NAD slightly increased (15% and 13%). Conversely, it reduced the PIN to the still satisfactory value of 40%. Computational analysis based on molecular and periodic density functional theory calculations was used to complement our experimental findings. Calculations of the average local ionization energy indicate that the PIN is the most reactive of all three considered molecules in terms of removing an electron from it.
This study aimed to investigate whether different doses of specific phenolic acids (chlorogenic acid, caffeic acid, ferulic acid, gallic acid, protocatechuic acid,
-hydroxybenzoic acid, syringic ...acid, vanillic acid, and
-coumaric acid), alone or in combination, can inhibit the early growth of the common ragweed (
L., Asterales: Asteraceae). A seed bioassay was performed in Petri dishes and placed in a climate chamber to assess the effects of five dose levels of phenolic acids to radicle and shoot length, as well seedling biomass of
. The lowest dose of phenolic acid corresponded to the natural phenolic acid concentration previously reported in dry plant tissue samples from Brassicaceae cover crop plants. Results show that the inhibition of the early growth of
depends strongly on phenolic acid. Across different treatments, high doses of phenolic acids significantly shortened shoots and radicles, as well as reduced seedling biomass. Treating seeds with ferulic acid alone, vanillic acid alone,
-hydroxybenzoic acid alone, or a mixture of all phenolic acids significantly reduced all early growth parameters. The estimated effective dose for the 50% inhibition (ED
) of radicle growth in
seedlings was 368.39 ± 59.85 × 10
mol with ferulic acid, 135.41 ± 17.65 × 10
mol with
-coumaric acid, 810.36 ± 134.15 × 10
mol with
-hydroxybenzoic acid, and 160.11 ± 12.30 × 10
mol with the combination of all phenolic acids.
The anodic oxidation method is applied for preparation of TiO2 nanotube (NT) arrays on Ti6Al4V alloy substrates. The NTs were of four different diameters (60, 65, 80 and 120 nm) and wall thicknesses ...in the range 8–14 nm. The as-prepared samples were characterized and then annealed at 450 °C in air for 2 h. The surface morphology of the samples is characterized by field emission scanning electron microscopy which reveals uniformly distributed nanotube arrays over the substrate. Raman scattering measurements show that the NTs in as-prepared samples are amorphous. In annealed samples rutile phase and a small amount of anatase phase are detected by both Raman scattering and X-ray diffraction methods. It is assumed that the rutile phase is related to a TiO2 film with rutile structure formed during the annealing between NTs and alloy substrate. The retarded formation of anatase phase is connected with inclusion in the TiO2 nanotubes of external atoms coming from the substrate. The amount and crystallinity of anatase phase decreases with decreasing nanotube diameter and/or wall thickness which is assigned to size-induced increase of the NT crystallization temperature. Investigations of the optical response of the samples to ethanol vapors at room temperature reveal relations between the NT size and their ethanol sensitivity. The response of as-prepared nanotube arrays increases with decreasing nanotube diameter while in the annealed samples an opposite trend is observed. The size dependence seen for as-prepared samples is related to an increase of the total adsorbing surface with decreasing NT diameter. The result obtained for the annealed samples is assigned to annealing induced changes in the morphology and composition of the internal surface of NTs.
•TiO2 nanotubes grown on Ti6Al4V substrates and annealed at 450 °C are investigated.•Rutile phase is detected upon annealing related to a film grown on substrate surface.•NTs diameter and wall thickness affect the amount of anatase phase in annealed NTs.•The NT crystallization is influenced by incorporation of Al atoms and size effects.•Optical response to ethanol of as-prepared and annealed NTs is explored and discussed.
Grapevine virus A (GVA) is an economically important virus and a member of the genus
(family
) that causes a range of symptoms with qualitative and quantitative effects on grape production. Wild and ...domesticated species of
, including hybrids used as rootstocks, are considered important natural hosts of GVA. Mechanical transmission to some herbaceous plant species, graft transmission, and vector transmission from grape to grape by various mealybugs and soft scale insects have been reported. Under laboratory and greenhouse conditions, this study demonstrates the transmission of GVA from grapes to alternative hosts by the vine mealybug (
). Results of ELISA, end-point one-step RT-PCR, and real-time RT-PCR, and in some cases electron microscopy and genome sequencing, confirmed successful transmission to three new plant species commonly found in Croatian vineyards: velvetleaf (
), redroot pigweed (
), and field poppy (
), along with
and the previously known host
, with variable infection rates. Depending on the host species, symptoms in the form of leaf reddening, yellow spots, reduced growth of lateral shoots, systemic vein clearing, foliar deformation and rugosity, and dwarfism were observed in GVA-infected plants, whereas no symptoms were observed in infected plants of
. Reverse transmission from these new hosts to grapevines by
was not successful. These results confirm four new GVA host species and open new research venues.
The effects of common precursors used in the synthesis of CeO2 nanopowders were investigated, and the structural and spectral properties of the resulting products were compared. Two cerium (III) ...salts, i.e., Ce(NO3)3·6H2O and CeCl3·7H2O, and two cerium (IV) salts, i.e., Ce(SO4)2·4H2O and (NH4)2Ce(NO3)6 were applied. The proposed procedures for the CeO2 preparations were realized using the same hydrothermal treatment conditions. The products were characterized using X-ray powder diffraction (XRD) and thermogravimetric (TG) analysis, and the morphology was determined using scanning (SEM) and transmission electron microscopy (TEM). The spectral properties of the obtained nanopowders were characterized by FT-IR, Raman scattering and UV–vis spectroscopy. The results revealed the influence of the precursors on the crystallinity, crystallite size, band gap energy, morphology and purity of the synthesized samples.
At the global level, the invasion of alien organisms is considered the second largest threat to biodiversity. The assumption is that the high allelopathic potential is one of the features that helps ...invasive plant species to spread to new areas. Allelopathic potential of 8 invasive plant species (donor species) and their impact on test-species was determined in the study. Donor species were velvetleaf (Abutilon theophrasti Med.), ragweed (Ambrosia elatior L.), jimsonweed (Datura stramonium L.), common cocklebur (Xanthium strumarium L.), tree of heaven (Ailanthus altissima (Mill.) Swingle), indigo bush (Amorpha fruticosa L.), Japanese knotweed (Reynoutria japonica Houtt.) and giant goldenrod (Solidago gigantea Aiton). Three cultivated plant species from 3 different plant families were used as test-species. Test-species were: oat (Avena sativa L.), oilseed rape (Brassica napus subsp. oleifera) and sunflower (Helianthus annuus L.). Water extracts made of whole plants of donor species were applied to the seeds of the test-species. High allelopathic potential was proven for all species included in experiment. Allelopathic effects were exclusively negative. Impact on germination for all species was much lower in relation to the impact on the radicle and shoot length of the test-species. Perennial donor species had a stronger allelopathic potential than annual donor species. Tree of heaven was the species with the strongest allelopathic potential. Its extracts inhibited germination, radicle and shoot length of oilseed rape by 19%, 94.88% and 98.91% respectively.
Weeds can be one of the most severe threats to crop production, especially when they are widespread and highly adaptable. Part of the adaptive strategy of plants is the ability to germinate in ...different conditions. Germination is the first developmental phase of plant life and is fundamental for its establishment. In this work, the germination of two populations of
L. at two different sites in Croatia (one cropped, the other non-agricultural) was tested under a wide range of salinity stress, 4, 8, 12, and 16 dS/m, and pH stress, values 1-9, at two temperature ranges of 15-25 °C and 18-30 °C. The results show that this species can tolerate high salinity, with a high number of seeds germinating, even under the highest level of saline stress and especially at higher temperatures: 21.7% of seeds germinated at 15-25 °C and 51.2% at 18-30 °C.
also appears to be quite acid tolerant, with a significant reduction in germination only at pH 2, and no germination only at pH 1. Germination was always higher at higher temperatures, independently of abiotic stress. Although there were some differences between the two populations in the final germination percentages, they were similar in their responses to the abiotic stresses.
Herbicides are the most commonly used means of controlling the growth of Ambrosia artemisiifolia L. Their constant use has led to the development of resistant populations. They can be evaluated by ...studying seed germination and the corresponding grown plants, but A. artemisiifolia exhibits seed dormancy, preventing germination and delaying research. Here, we developed a simple and rapid method to stimulate germination of freshly collected or stored A. artemisiifolia seeds. The germination of A. artemisiifolia freshly collected/stored seeds was evaluated after storage, stratification, and chemical treatments (ethephon, gibberellic acid (GA3), thiourea, KNO3). Ethephon or ethephon + GA3 improved freshly collected seed germination by 88 and 95%, respectively, and germination of stored seeds by 78 and 80%, respectively. In addition, placing the seeds of A. artemisiifolia in ethephon, GA3, ethephon + GA3, or thiourea solutions caused the freshly collected seeds to germinate faster than stored seeds or nontreated seeds. In contrast, the conditioning of seeds in these solutions favored germination of stored seeds, especially when ethephon + GA3 or GA3 was used. Imbibition of the freshly collected A. artemisiifolia seeds in a mixture of ethephon and GA3 can effectively overcome primary dormancy when rapid experimental results are needed. For seeds requiring prolonged storage, conditioning in ethephon, GA3, or thiourea solutions may be applied to promote germination.
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