PIXE analysis of iron in rabbit cerebellum after exposure to radiofrequency electromagnetic fields.

PURPOSE: We investigated iron accumulation and the possible mechanisms in the rabbit cerebellum after the exposure to the real GSM and generated radiofrequency electromagnetic fields (RF EMF) using inductively coupled plasma mass spectrometry (ICP MS) and particles induced X-ray emission (PIXE). MATERIALS AND METHODS: Four groups of rabbits were exposed to the real EMF, generated EMF, combination of both the real and generated signals and the control group with no exposition. For determination of iron concentration in the four groups of cerebellum samples ICP MS was used. Iron accumulation in samples by PIXE analysis using the 3 MeV proton beam was carried out. RESULTS: Iron concentration measured by ICP MS revealed no significant differences for all the groups. PIXE results showed a focal accumulation of iron with the size up to 3 mm. Highest concentration of iron after exposure to real signal was observed. CONCLUSION: We suggest that the iron accumulation after the exposure to RF ELF is not the result of higher permeability of blood-brain barrier and leaking out of iron from the bloodstream into the brain cells and tissues. It could be the result of an iron actuation and its redistribution in the tissue (Fig. 2, Ref. 86).

The Effect of High Selenite and Selenate Concentrations on Ferric Oxyhydroxides Transformation under Alkaline Conditions.

Iron-based nanomaterials have high technological impacts on various pro-environmental applications, including wastewater treatment using the co-precipitation method. The purpose of this research was to identify the changes of iron nanomaterial's structure caused by the presence of selenium, a typical water contaminant, which might affect the removal when the iron co-precipitation method is used. Therefore, we have investigated the maturation of co-precipitated nanosized ferric oxyhydroxides under alkaline conditions and their thermal transformation into hematite in the presence of selenite and selenate with high concentrations. Since the association of selenium with precipitates surfaces has been proven to be weak, the mineralogy of the system was affected insignificantly, and the goethite was identified as an only ferric phase in all treatments. However, the morphology and the crystallinity of ferric oxyhydroxides was slightly altered. Selenium affected the structural order of precipitates, especially at the initial phase of co-precipitation. Still, the crystal integrity and homogeneity increased with time almost constantly, regardless of the treatment. The thermal transformation into well crystalized hematite was more pronounced in the presence of selenite, while selenate-treated and selenium-free samples indicated the presence of highly disordered fraction. This highlights that the aftermath of selenium release does not result in destabilization of ferric phases; however, since weak interactions of selenium are dominant at alkaline conditions with goethite's surfaces, it still poses a high risk for the environment. The findings of this study should be applicable in waters affected by mining and metallurgical operations.

Study of Mono- and Bimetallic Fe and Mn Oxide-Supported Clinoptilolite for Improved Pb(II) Removal.

A cost-effective, iron- and manganese-oxide-supported clinoptilolite-based rock was prepared. Based on its nanoporous structure, it worked as a nanoreactor, thereby providing enhanced functionalities. The mono- and bimetallic Fe- and Mn-oxide-supported clinoptilolite was thoroughly characterized with thermoanalytical FT-IR, XRD, SEM, and XPS spectroscopy. All the spectral procedures that were used confirmed the occurrence of a new MnO2 phase (predominantly birnessite), including mostly amorphous iron oxi(hydr)oxide (FeO(OH)) species on the surface of the above-synthesized adsorbents. The synthesized products validated a considerably higher adsorption capacity toward Pb(II) pollutants compared to the natural clinoptilolite. The following order of a(max) toward Pb(II) was found: MnOx-zeolite (202.1 mg/g) > FeO(OH)-MnOx-zeolite (101.3 mg/g) > FeO(OH)-zeolite (80 mg/g) > natural zeolite (54.9 mg/g). The adsorption equilibrium data were analyzed by the two-parameter empirical isotherm models Langmuir, Freundlich, and BET as well as the three-parameter Redlich-Peterson isotherm.

Increased Colloidal Stability and Decreased Solubility-Sol-Gel Synthesis of Zinc Oxide Nanoparticles with Humic Acids.

Adding the humic acid coating to the nanoparticles of zinc oxide (ZnO-NP) may improve the properties necessary for their colloidal stability. To show how humic acid coating affects the properties of ZnO-NP, three differently sol-gel synthesized ZnO-NP were synthesized: pristine zinc oxide nanoparticles without coating (p-ZnO-NP) and humic acid coated zinc oxide nanoparticles at two different initial concentrations of 20 mg/L (HA20-ZnO-NP) and 200 mg/L (HA200-ZnO-NP) of humic acids in the starting solution. All ZnO-NP were found to be nanocrystals of mineral zincite exhibiting wurtzite crystal symmetry. Transmission electron microscopy showed that capping by humic acids during synthesis decreased the size of HA20-ZnO-NP and HA200-ZnO-NP compared to p-ZnO-NP nanoparticles. Via experiments, HA20-ZnO-NP were found to dissolve less and have a similar or higher stability than both p-ZnO-NP and HA200-ZnO-NP.

Removal of aluminium from aqueous solution by four wild-type strains of Aspergillus niger.

This paper provides a unique comparison of the performance of four wild-type Aspergillus niger strains in remediation of aluminium(III)-contaminated aqueous solutions. The direct fungal aluminium removal via biosorption and bioaccumulation was compared among all fungal strains, including bioaccumulation efficiency during dynamic and static cultivation. Our results indicate that aluminium bioaccumulation by living biomass outperformed biosorption, although biosorption by non-living biomass is a less time-demanding process. Among others, only one strain significantly differed regarding comparison of dynamic and static bioaccumulation. In this case, a significantly higher removal performance was achieved under dynamic cultivation conditions at initial aluminium(III) concentrations over 2.5 mg L-1. Although the fungal sensitivity towards aluminium(III) differed among selected fungal strains, there was no apparent correlation between the strains' removal performance and their adaptive mechanisms.

Bismuth(III) volatilization and immobilization by filamentous fungus Aspergillus clavatus during aerobic incubation.

As with many metals, bismuth can be accumulated or transformed by microorganisms. These interactions affect microbial consortia and bismuth environmental behaviour, mobility, and toxicity. Recent research focused specifically on bismuth anaerobic transformation by bacteria and archaea has inspired the evaluation of the mutual interactions between bismuth and filamentous fungi as presented in this article. The Aspergillus clavatus fungus proved resistant to adverse effects from bismuth contamination in culture medium with up to a concentration of 195 µmol L(-1) during static 15- and 30-day cultivation. The examined resistance mechanism includes biosorption to the fungal surface and biovolatilization. Pelletized fungal biomass has shown high affinity for dissolved bismuth(III). Bismuth biosorption was rapid, reaching equilibrium after 50 min with a 0.35 mmol g(-1) maximum sorption capacity as calculated from the Langmuir isotherm. A. clavatus accumulated ≤70 µmol g(-1) of bismuth after 30 days. Preceding isotherm study implications that most accumulated bismuth binds to cell wall suggests that biosorption is the main detoxification mechanism. Accumulated bismuth was also partly volatilized (≤1 µmol) or sequestrated in the cytosol or vacuoles. Concurrently, ≤1.6 µmol of bismuth remaining in solution was precipitated by fungal activity. These observations indicate that complex mutual interactions between bismuth and filamentous fungi are environmentally significant regarding bismuth mobility and transformation.

Essential Role of CgErg6p in Maintaining Oxidative Stress Tolerance and Iron Homeostasis in Candida glabrata.

The human pathogenic fungus Candida glabrata is the second leading cause of candidemia, a life-threatening invasive mycosis. Clinical outcomes are complicated by reduced susceptibility of C. glabrata to azoles together with its ability to evolve stable resistance to both azoles and echinocandins following drug exposure. Compared to other Candida spp., C. glabrata displays robust oxidative stress resistance. In this study, we investigated the impact of CgERG6 gene deletion on the oxidative stress response in C. glabrata. CgERG6 gene encodes sterol-24-C-methyltransferase, which is involved in the final steps of ergosterol biosynthesis. Our previous results showed that the Cgerg6Δ mutant has a lower ergosterol content in its membranes. Here, we show that the Cgerg6Δ mutant displays increased susceptibility to oxidative stress inducing agents, such as menadione, hydrogen peroxide and diamide, accompanied with increased intracellular ROS production. The Cgerg6Δ mutant is not able to tolerate higher concentrations of iron in the growth media. We observed increased expression of transcription factors, CgYap1p, CgMsn4p and CgYap5p, together with increased expression of catalase encoding the CgCTA1 gene and vacuolar iron transporter CgCCC1 in the Cgerg6Δ mutant cells. However, it seems that the CgERG6 gene deletion does not influence the function of mitochondria.

Agronomic Investigation of Spray Dispersion of Metal-Based Nanoparticles on Sunflowers in Real-World Environments.

In environmental and agronomic settings, even minor imbalances can trigger a range of unpredicted responses. Despite the widespread use of metal-based nanoparticles (NPs) and new bio-nanofertilizers, their impact on crop production is absent in the literature. Therefore, our research is focused on the agronomic effect of spray application of gold nanoparticles anchored to SiO2 mesoporous silica (AuSi-NPs), zinc oxide nanoparticles (ZnO-NPs), and iron oxide nanoparticles (Fe3O4-NPs) on sunflowers under real-world environments. Our findings revealed that the biosynthetically prepared AuSi-NPs and ZnO-NPs were highly effective in enhancing sunflower seasonal physiology, e.g., the value of the NDVI index increased from 0.012 to 0.025 after AuSi-NPs application. The distribution of leaf trichomes improved and the grain yield increased from 2.47 t ha-1 to 3.29 t ha-1 after ZnO-NPs application. AuSi-NPs treatment resulted in a higher content of essential linoleic acid (54.37%) when compared to the NPs-free control (51.57%), which had a higher determined oleic acid. No NPs or residual translocated metals were detected in the fully ripe sunflower seeds, except for slightly higher silica content after the AuSi-NPs treatment. Additionally, AuSi-NPs and NPs-free control showed wide insect biodiversity while ZnO-NPs treatment had the lowest value of phosphorus as anti-nutrient. Contradictory but insignificant effect on physiology, yield, and insect biodiversity was observed in Fe3O4-NPs treatment. Therefore, further studies are needed to fully understand the long-term environmental and agricultural sustainability of NPs applications.

Arsenic and selenium interactive effect on alga Desmodesmus quadricauda.

Substances known to be toxic in one-component solutions often exhibit unexpected effects when present in mixtures. Only a few efforts have been made to assess the effect of As-Se mixture in algae or plants in general. Due to the lack of information on this topic, the aim of this study was to examine the As-Se interactive effect in the alga species Desmodesmus quadricauda. The initial density of algal cells was 1.9×10(4), cultures were permanently illuminated (70µEm(-2)s(-1)) and As and Se adverse effect was expressed as EC (effective concentration) value. For all experiments three EC (EC(10), EC(20), EC(50)) values for both metalloids were used: for As 26.20, 29.05, 35.38mg L(-1) and for Se 1.93, 3.65, 12.24mg L(-1), respectively. During this study algal biomass growth, lipid peroxidation and protein-bound thiol content parameters were used to assess the As-Se interactions. The reciprocal effect of the elements on their uptake by the alga was also determined. The As-treated algae supplemented with Se exhibited impaired growth indicating a synergistic interaction between the two elements. In samples treated with As-Se mixture, the total algal As content showed marked increase depending on the Se concentration in the mixture. Se uptake was also positively affected by rising As concentrations in the mixture. Consequently, the As-Se-treated algae experienced greater damage to membranes, evidenced by marked elevation of the TBARS (thiobarbituric acid reactive substances) content. The TBARS content increased to a maximum level by 29.05mg L(-1) of As and 3.65mg L(-1) of Se, which was around 70 percent higher than that of the control. The thiol content was very close to that of the control treatment over the entire concentration range and for all As and Se combinations tested. Possible explanation for the synergism observed in D. quadricauda, is that the elevated uptake of As and Se upon their interaction and impaired antioxidant system, has added to the toxicity of the elements.

Method for preparation of planar alginate hydrogels by external gelling using an aerosol of gelling solution.

Preparation of planar alginate hydrogels by external gelling requires slow rate of exposure of alginate solution to gelling ions to control gelling process and hydrogel properties. We tackled this issue by exposing solution of sodium alginate to solution of CaCl2 applied as aerosol at exposure rate of 7.5 mg cm(-2) s(-1). Gelling conditions varied with respect to concentrations of sodium alginate (1-3 wt.%) and CaCl2 (0.5-4 wt.%), exposure time (2.5-40 min), the 2nd gelling step in the presence of barium ions, and the storage step. Dimensional stability and Young's modulus values were the principal determined quantities to examine the correlation between hydrogel properties and gelling protocol. The content of calcium ions in hydrogel after gelling by CaCl2 aerosol reveals that the maximum binding capacity of calcium ions by alginate chains was reached. Obtained data suggest that an unusual gelling mechanism related to exposure of sodium alginate to aerosol of gelling solution does not need to be considered since the properties of planar alginate hydrogels follow the trends relevant to general knowledge about alginate hydrogels.

Analytical application of nano-sized titanium dioxide for the determination of trace inorganic antimony in natural waters.

In this work, solid phase extraction (SPE) using nano-sized TiO2 as a solid sorbent was used for separation/preconcentration of total inorganic antimony (iSb) before its determination by electrothermal atomic absorption spectrometry (ETAAS). After adsorption of iSb onto nano-sized TiO2, direct TiO2-slurry sampling was used for sample injection into a graphite tube. The conditions for the reliable slurry sampling together with careful control of the temperature program for the slurry solutions were worked out. Extraction conditions for both inorganic antimony species (Sb(III) and Sb(V)) and interference studies of coexisting ions were studied in detail. The accuracy of the optimized method was checked by the certified reference material (CRM) for trace elements in lake water TMDA-61. Finally, the optimized method was used for the determination of trace inorganic antimony in synthetic and natural waters.

Optimization of determination of platinum group elements in airborne particulate matter by inductively coupled plasma mass spectrometry.

Determination of automotive traffic-emitted platinum group metals (PGM) by inductively coupled plasma quadrupole mass spectrometry (ICP-MS) was optimized. The interferences from Sr, Cu, Pb, Y, Cd, Zr and Hf were evaluated using model solutions. Plasma radiofrequency (RF) power and nebulizer gas flow were optimized for 103Rh, 105Pd, 108Pd and 195Pt. Two standard reference materials were analyzed: SARM-7 Platinum ore and BCR-723 Road dust. The optimized procedure was used to analyze samples of airborne particulate matter collected in the urban site with heavy automotive traffic in the centre of Bratislava, Slovakia.

Crystal structure of bis-(ammonium) bis-[penta-aqua-(di-methyl-formamide)-zinc(II)] deca-vanadate tetra-hydrate.

The crystalline product (NH4)2[Zn(C3H7NO)(H2O)5]2[V10O28]·4H2O was success-fully isolated from an H2O/DMF solvent combination by evaporation at ambient temperature. The salt crystallizes in the P21/n space group. Imidazole, initially used in the synthesis but not present in the product, and DMF solvent appear to affect the synthesis and crystallization as structural-directing agents. In the title compound, the complex cation [Zn(H2O)5(DMF)]2+ acts as a counter-ion without being directly coordinated to the deca-vanadate anion. An extensive framework of hydrogen bonds integrates the whole architecture as evidenced by X-ray crystallography. The polyoxometalate [V10O28]6- lies on a center of symmetry while the complex cation [Zn(H2O)5(DMF)]2+ links three adjacent anions through a set of 2 + 2 + 3 hydrogen bonds.

Thermoacidophilic Bioleaching of Industrial Metallic Steel Waste Product.

The continuous deposition of hazardous metalliferous wastes derived from industrial steelmaking processes will lead to space shortages while valuable raw metals are being depleted. Currently, these landfilled waste products pose a rich resource for microbial thermoacidophilic bioleaching processes. Six thermoacidophilic archaea (Sulfolobus metallicus, Sulfolobus acidocaldarius, Metallosphaera hakonensis, Metallosphaera sedula, Acidianus brierleyi, and Acidianus manzaensis) were cultivated on metal waste product derived from a steelmaking process to assess microbial proliferation and bioleaching potential. While all six strains were capable of growth and bioleaching of different elements, A. manzaensis outperformed other strains and its bioleaching potential was further studied in detail. The ability of A. manzaensis cells to break down and solubilize the mineral matrix of the metal waste product was observed via scanning and transmission electron microscopy. Refinement of bioleaching operation parameters shows that changes in pH influence the solubilization of certain elements, which might be considered for element-specific solubilization processes. Slight temperature shifts did not influence the release of metals from the metal waste product, but an increase in dust load in the bioreactors leads to increased element solubilization. The formation of gypsum crystals in course of A. manzaensis cultivation on dust was observed and clarified using single-crystal X-ray diffraction analysis. The results obtained from this study highlight the importance of thermoacidophilic archaea for future small-scale as well as large-scale bioleaching operations and metal recycling processes in regard to circular economies and waste management. A thorough understanding of the bioleaching performance of thermoacidophilic archaea facilitates further environmental biotechnological advancements.

Sequential scavenging and measurement of seawater radiocesium concentrations and plutonium isotopic ratios offshore Fukushima.

The scientific interest in radiocesium and plutonium found in the oceans and seas has increased enormously in the past years as a consequence of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident and is expected to be ongoing due to many unresolved questions. Hence, continuous development of new and verification of old analytical methods should be at the top of the list of the community, working on the topic. In this study, we processed and analyzed several seawater samples, collected in different time frames (2011-2015) from the North Pacific Ocean offshore Fukushima, to determine their radiocesium activities, 134Cs/137Cs activity ratios and 240Pu/239Pu isotopic ratios using the sequential scavenging method, gamma spectrometry and accelerator mass spectrometry (AMS). The observed radiocesium levels in seawater (0.07-0.042 Bq L-1) clearly indicated that the investigated region remained impacted by releases from the damaged power plant even after four years after the accident. Regarding plutonium, its successful separation from large volume seawater samples was confirmed by detection of 240Pu by AMS. However, several problems emerged during the analyzes, which we tried to address with the use of additional methods (e.g., measurements of uranium by ICPMS). The efficiencies of the applied methods and other issues are also discussed.

Effects of Foliar Application of ZnO Nanoparticles on Lentil Production, Stress Level and Nutritional Seed Quality under Field Conditions.

Nanotechnology offers new opportunities for the development of novel materials and strategies that improve technology and industry. This applies especially to agriculture, and our previous field studies have indicated that zinc oxide nanoparticles provide promising nano-fertilizer dispersion in sustainable agriculture. However, little is known about the precise ZnO-NP effects on legumes. Herein, 1 mg·L-1 ZnO-NP spray was dispersed on lentil plants to establish the direct NP effects on lentil production, seed nutritional quality, and stress response under field conditions. Although ZnO-NP exposure positively affected yield, thousand-seed weight and the number of pods per plant, there was no statistically significant difference in nutrient and anti-nutrient content in treated and untreated plant seeds. In contrast, the lentil water stress level was affected, and the stress response resulted in statistically significant changes in stomatal conductance, crop water stress index, and plant temperature. Foliar application of low ZnO-NP concentrations therefore proved promising in increasing crop production under field conditions, and this confirms ZnO-NP use as a viable strategy for sustainable agriculture.

Mobilisation of hazardous elements from arsenic-rich mine drainage ochres by three Aspergillus species.

Natural ferric ochres that precipitate in streambeds at abandoned mining sites are natural scavengers of various metals and metalloids. Thus, their chemical and structural modification via microbial activity should be considered in evaluation of the risks emerging from probable spread of contamination at mining sites. Our results highlight the role of various aspergilli strains in this process via production of acidic metabolites that affect mobility and bioavailability of coprecipitated contaminants. The Mössbauer analysis revealed subtle structural changes of iron in ochres, while the elemental analysis of non-dissolved residues of ochres that were exposed to filamentous fungi suggest coinciding bioextraction of arsenic and antimony with extensive iron mobilisation. However, the zinc bioextraction by filamentous fungi is less likely dependent on iron leaching from ferric ochres. The strain specific bioextraction efficiency and subsequent bioaccumulation of mobilised metals resulted in distinct tolerance responses among the studied soil fungal strains. However, regardless the burden of bioextracted metal(loid)s on its activity, the Aspergillus niger strain has shown remarkable capability to decrease pH of its environment and, thus, bioextract significant and environmentally relevant amounts of potentially toxic elements from the natural ochres.

Properties and Degradation Performances of Biodegradable Poly(lactic acid)/Poly(3-hydroxybutyrate) Blends and Keratin Composites.

From environmental aspects, the recovery of keratin waste is one of the important needs and therefore also one of the current topics of many research groups. Here, the keratin hydrolysate after basic hydrolysis was used as a filler in plasticized polylactic acid/poly(3-hydroxybutyrate) blend under loading in the range of 1-20 wt%. The composites were characterized by infrared spectroscopy, and the effect of keratin on changes in molar masses of matrices during processing was investigated using gel permeation chromatography (GPC). Thermal properties of the composites were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of keratin loading on the mechanical properties of composite was investigated by tensile test and dynamic mechanical thermal analysis. Hydrolytic degradation of matrices and composites was investigated by the determination of extractable product amounts, GPC, DSC and NMR. Finally, microbial growth and degradation were investigated. It was found that incorporation of keratin in plasticized PLA/PHB blend provides material with good thermal and mechanical properties and improved degradation under common environmental conditions, indicating its possible application in agriculture and/or packaging.

Bioleaching of Manganese Oxides at Different Oxidation States by Filamentous Fungus Aspergillus niger.

This work aimed to examine the bioleaching of manganese oxides at various oxidation states (MnO, MnO·Mn2O3, Mn2O3 and MnO2) by a strain of the filamentous fungus Aspergillus niger, a frequent soil representative. Our results showed that the fungus effectively disintegrated the crystal structure of selected mineral manganese phases. Thereby, during a 31-day static incubation of oxides in the presence of fungus, manganese was bioextracted into the culture medium and, in some cases, transformed into a new biogenic mineral. The latter resulted from the precipitation of extracted manganese with biogenic oxalate. The Mn(II,III)-oxide was the most susceptible to fungal biodeterioration, and up to 26% of the manganese content in oxide was extracted by the fungus into the medium. The detected variabilities in biogenic oxalate and gluconate accumulation in the medium are also discussed regarding the fungal sensitivity to manganese. These suggest an alternative pathway of manganese oxides' biodeterioration via a reductive dissolution. There, the oxalate metabolites are consumed as the reductive agents. Our results highlight the significance of fungal activity in manganese mobilization and transformation. The soil fungi should be considered an important geoactive agent that affects the stability of natural geochemical barriers.

Fungal Mobilization of Selenium in the Presence of Hausmannite and Ferric Oxyhydroxides.

Bioleaching of mineral phases plays a crucial role in the mobility and availability of various elements, including selenium. Therefore, the leachability of selenium associated with the surfaces of ferric and manganese oxides and oxyhydroxides, the prevailing components of natural geochemical barriers, has been studied in the presence of filamentous fungus. Both geoactive phases were exposed to selenate and subsequently to growing fungus Aspergillus niger for three weeks. This common soil fungus has shown exceptional ability to alter the distribution and mobility of selenium in the presence of both solid phases. The fungus initiated the extensive bioextraction of selenium from the surfaces of amorphous ferric oxyhydroxides, while the hausmannite (Mn3O4) was highly susceptible to biodeterioration in the presence of selenium. This resulted in specific outcomes regarding the selenium, iron, and manganese uptake by fungus and residual selenium concentrations in mineral phases as well. The adverse effects of bioleaching on fungal growth are also discussed.