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Silver nanoparticles (AgNPs) are of great interest due to their antimicrobial properties, but their reactivity and toxicity pose a significant risk to aquatic ecosystems. In biological systems, AgNPs tend to aggregate and dissolve, so they are often stabilized by agents that affect their physicochemical properties. In this study, microalga Chlorella vulgaris was used as a model organism to evaluate the effects of AgNPs in aquatic habitats. Algae were exposed to AgNPs stabilized with citrate and cetyltrimethylammonium bromide (CTAB) agents and to AgNO3 at concentrations that allowed 75% cell survival after 72 h. To investigate algal response, silver accumulation, ROS content, damage to biomolecules (lipids, proteins, and DNA), activity of antioxidant enzymes (APX, PPX, CAT, SOD), content of non-enzymatic antioxidants (proline and GSH), and changes in ultrastructure were analyzed. The results showed that all treatments induced oxidative stress and adversely affected algal cells. AgNO3 resulted in the fastest death of algae compared to both AgNPs, but the extent of oxidative damage and antioxidant enzymatic defense was similar to AgNP-citrate. Furthermore, AgNP-CTAB showed the least toxic effect and caused the least oxidative damage. These results highlight the importance of surface-stabilizing agents in determining the phytotoxicity of AgNPs and the underlying mechanisms affecting aquatic organisms.

Silver nanoparticles represent a threat to biota and have been shown to cause harm through a number of mechanisms, using a wide range of bioassay endpoints. While nanoparticle concentration has been primarily considered, comparison of studies that have used differently sized nanoparticles indicate that nanoparticle diameter may be an important factor that impacts negative outcomes. In considering this, the aim of the present study was to determine if different sizes of silver nanoparticles (AgNPs; 10, 20, 40, 60 and 100 nm) give rise to similar effects during embryogenesis of Mediterranean sea urchins

Silver nanoparticles (AgNPs) attract a great deal of attention due to their antimicrobial effects, for which they are implemented in a wide range of commercial products. However, due to their reactivity and toxicity, they pose a significant risk to aquatic ecosystems. To evaluate the impact of AgNPs on aquatic habitats, Chlorella vulgaris was used as a model organism. To assess the effect of AgNPs on C. vulgaris, algal cultures were grown in liquid BBM nutrient medium for 4 days after which they were exposed to AgNPs coated with citrate or CTAB, and to AgNO3 which was used as ionic Ag control. Concentration endpoints were obtained by growth inhibition test (72 h) and the estimated 25% growth rate inhibition (EC25) values for AgNP-citrate, AgNP-CTAB and AgNO3 were 0.188 mg L-1, 0.895 mg L-1 and 0.130 mg L-1, respectively. After 72h-treatment, the amount of synthesized oxygen, and photosystem II efficiency were analysed to address the impact of AgNPs on the photosynthetic apparatus. Furthermore, reactive oxygen species (ROS) levels and membrane lipid damage were analysed to investigate how well algae cells cope in the presence of AgNPs. To analyse ROS formation, algal suspensions were incubated with fluorogenic dyes (H2DCFDA and DHE) and visualized by a fluorescence microscope. To visualize ultrastructural changes, ultrathin sections of algal cells were analysed by transmission electron microscope (TEM). To further investigate the interaction between AgNPs and algal extracellular polymeric substances (EPS), cells were observed directly by TEM, and by fluorescence microscopy using FITC-labelled lectins. Obtained results indicate a differential effect of differently coated AgNPs on C. vulgaris since a significant reduction in newly synthesized oxygen and PSII efficacy after all treatments compared to the control were observed. Furthermore, differentially increased ROS content after all treatments (Fig. 1), in regard to used coatings, compared to control is suggestive of membrane lipids damage through ROS molecules. TEM analyses showed damaged ultrastructure (Fig. 2) with multiple NPs in EPS of algal cells (Fig. 3), while fluorescence microscopy showed increased EPS synthesis after all treatments, especially after AgNPs-CTAB, which could alleviate AgNPs toxic effect (Fig. 4). In conclusion, all forms of silver (AgNP-citrate, AgNP-CTAB and AgNO3) showed an adverse and detrimental effect primarily on the photosynthetic apparatus and membrane lipids mostly through increased synthesis of ROS molecules, where AgNP-citrate had most damaging effect. Due to the treatment with NPs, the synthesis of EPS increases, especially after AgNP- CTAB treatment, which can maintain and consequently reduce the harmful effect of AgNPs on the cells themselves.

Silver nanoparticles (AgNPs) are used in a variety of industries and due to their tendency to agglomerate in various media, they are commonly stabilised with various surface coatings such as carboxylic acids (citrate) or surfactant cetyltrimethylammonium bromide (CTAB) among others. As the use of AgNPs increases, so does the potential for their release into the aquatic environment. Since Chlorella vulgaris is one of the most ubiquitous algae inhabiting aquatic ecosystems, it is widely used as a model organism for assessing the impact of materials of anthropogenic origin, e.g. AgNPs, on aquatic habitats. To evaluate the impact of AgNP on C. vulgaris, algal cultures were grown in a liquid BBM nutrient medium for four days after which they were exposed to AgNPs coated with citrate or CTAB, and to AgNO3 which was used as ionic Ag control. Concentration endpoints were obtained by growth inhibition test (72 h) and the estimated 25% inhibition of growth rate (EC25) values for the AgNP-citrate, AgNP-CTAB and AgNO3 were 0.188 mg L- 1, 0.895 mg L-1 and 0.130 mg L-1, respectively. After 72 h treatment, the quantity of newly synthesised oxygen, damage to membrane lipids as measured through malondialdehyde (MDA) content, levels of reactive oxygen species (ROS) and activity of antioxidant enzymes (superoxide dismutase-SOD, catalase-CAT, ascorbate and pyrogallol peroxidase-APX and PPX) were analysed. To understand the ROS formation, algal suspensions were incubated with fluorogenic dyes through which hydroxyl and peroxyl activity within the cells (H2DCFDA) or superoxide (O2.−) generation (DHE) were determined, with both dyes providing a measure of other ROS activity through non-specific oxidation. Moreover, to further examine the interaction between AgNPs and algal cells, the treated organisms were observed directly by transmission electron microscopy (TEM). Obtained results showed detrimental effect of all treatments on the photosystem of C. vulgaris since significant decrease in oxygen synthesis was reported. Similarly, all treatments have increased ROS formation and MDA content, which is indicative of membrane lipids damage. Interestingly, only increases in PPX and CAT activity were observed after treatment with AgNP-citrate, while for APX and for other treatments a trend of decreasing activity of antioxidant enzymes were observed. TEM analysis of alge cells showed multiple NPs in extracellular polymeric substances (EPS) of algae cells which could aid in decreasing AgNPs toxic effect on algal cells. In conclusion, all silver nanoparticles (AgNP-citrate and AgNP-CTAB) and ionic silver showed damaging effects on the photosynthetic apparatus of C. vulgaris algae. The parallel increase in ROS formation and decrease in activity of the antioxidant machinery after 72 h treatment can be explained by an overproduction of ROS which consequently results in a change of enzyme structure and activity.

Understanding the effect that specific amino acids (AA) exert on calcium phosphate (CaPs) formation is proposed as a way of providing deeper insight into CaPs’ biomineralization and enabling the design of tailored-made additives for the synthesis of functional materials. Despite a number of investigations, the role of specific AA is still unclear, mostly because markedly different experimental conditions have been employed in different studies. The aim of this paper was to compare the influence of different classes of amino acids, charged (aspartic acid, Asp and lysine, Lys), polar (asparagine, Asn and serine, Ser) and non-polar (phenylalanine, Phe) on CaPs formation and transformation in conditions similar to physiological conditions. The precipitation process was followed potentiometrically, while Fourier transform infrared spectroscopy, powder X-ray diffraction, electron paramagnetic spectroscopy (EPR), scanning and transmission electron microscopy were used for the characterization of precipitates. Except for Phe, all investigated AAs inhibited amorphous calcium phosphate (ACP) transformation, with Ser being the most efficient inhibitor. In all systems, ACP transformed in calcium-deficient hydroxyapatite (CaDHA). However, the size of crystalline domains was affected, as well as CaDHA morphology. In EPR spectra, the contribution of different radical species with different proportions in diverse surroundings, depending on the type of AA present, was observed. The obtained results are of interest for the preparation of functionalized CaPs’, as well as for the understanding of their formation in vivo.

Soil pollution and toxicity have been investigated in the Gardanne area (southern France) at a range of sites around a recognized pollution source, a bauxite processing plant (BPP), and a power plant (PP). Soil samples were submitted to inorganic and organic analyses and tested for toxicity in two invertebrate models. Inorganic analysis was based on determining elemental concentrations by ICP-MS, encompassing a total of 26 elements including 13 rare earth elements (REEs), of the soil samples and their leachates after 24 or 48 h in seawater. Organic analyses were performed by measuring the sums of 16 polycyclic aromatic hydrocarbons (PAHs) and of total hydrocarbons (C-10 to C-40). Bioassays were carried out on the early life stages of three sea urchin species (Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis), and on a nematode (Caenorhabditis elegans). Sea urchin bioassays were evaluated by the effects of soil samples (0.1–0.5% dry wt/vol) on developing embryos and on sperm, and scored as: a) % developmental defects, b) inhibition of sperm fertilization success and offspring damage, and c) frequencies of mitotic aberrations. C. elegans 24 h-mortality assay showed significant toxicity associated with soil samples. The effects of soil samples showed heightened toxicity at two groups of sites, close to the BPP main entrance and around the PP, which was consistent with the highest concentrations found for metals and PAHs, respectively. Total hydrocarbon concentrations displayed high concentrations both close to BPP main entrance and to the PP. Further studies of the health effects of such materials in Gardanne are warranted.

The pervasive spread of microplastics (MPs) and nanoplastics (NPs) has raised significant concerns on their toxicity in both aquatic and terrestrial environments. These polymer-based materials have implications for plants, wildlife and human health, threatening food chain integrity and ultimate ecosystem resilience. An extensive – and growing – body of literature is available on MP- and NP-associated effects, including in a number of aquatic biota, with as yet limited reports in terrestrial environments. Effects range from no detectable, or very low level, biological effects to more severe outcomes such as (but not limited to) increased mortality rates, altered immune and inflammatory responses, oxidative stress, genetic damage and dysmetabolic changes. A well- established exposure route to MPs and NPs involves ingestion with subsequent incorporation into tissues. MP and NP exposures have also been found to lead to genetic damage, including effects related to mitotic anomalies, or to transmissible damage from sperm cells to their offspring, especially in echinoderms. Effects on the proteome, transcriptome and metabolome warrant ad hoc investigations as these integrated “omics” workflows could provide greater insight into molecular pathways of effect. Given their different physical structures, chemical identity and presumably different modes of action, exposure to different types of MPs and NPs may result in different biological effects in biota, thus comparative investigations of different MPs and NPs are required to ascertain the respective effects. Furthermore, research on MP and NP should also consider their ability to act as vectors for other toxicants, and possible outcomes of exposure may even include effects at the community level, thus requiring investigations in mesocosm models.

Nanočestice srebra (AgNP) dobro su poznate po svojim antimikrobnim svojstvima u mnogim komercijalno dostupnim proizvodima, ali zbog svoje toksičnosti i reaktivnosti predstavljaju rizik za vodeni okoliš [1]. U ovom istraživanju korištena je modelna fotosintetska alga, Chlorella vulgaris. Da bi se procijenio učinak AgNP stabiliziranih polivinilpirolidonom (AgNP-PVP) i ionima srebra (AgNO3) na alge, izmjeren je njihov rast, lipidna peroksidacija i aktivnost katalaze nakon izlaganja koncentracijama 0.5, 1.0, 1.5 i 2.0 mg L-1 nakon 5, 24 i 48 sati u modificiranom tekućem hranjivom BBM mediju. Nadalje, analizirane su promjene pH, razine otopljenog kisika i spektri apsorpcije u rasponu od 300-800 nm u kulturama algi nakon istog trajanja tretmana. Budući da stresni uvjeti negativno utječu na sintezu proteina ribuloza bisfosfat karboksilaze (Rubisco), koristili smo imunohistokemijsku metodu za analizu ekspresije velikog lanca proteina Rubisco kako bismo procijenili stanje algi nakon tretmana. Nadalje, kako bi se vizualizirale ultrastrukturne promjene nakon tretmana, stanice algi ispitivane su pomoću transmisijske elektronske mikroskopije (TEM). Nakon tretmana s AgNP-PVP ili AgNO3 primijećeno je značajno smanjenje broja stanica ovisno o dozi tretmana te povećanje peroksidacije lipida i otopljenog kisika. Nadalje, izmjeren je porast aktivnosti katalaze nakon svih tretmana, dok je porast pH primijećen nakon 24 i 48 sati za tretmane s 1, 5 i 2, 0 mg L-1 AgNP-PVP i AgNO3. Apsorbancija vidljive svjetlosti značajno se smanjila nakon svih tretmana s AgNP-PVP i AgNO3, s najočitijim padom u karakterističnim rasponima apsorpcije klorofila a i b. Imunohistokemijska analiza je otkrila značajno smanjenje velike podjedinice proteina Rubisco nakon tretmana s AgNP-PVP ili AgNO3 čije smanjenje je bilo ovisno o dozi tretmana. Analiza TEM je pokazala da su stanice nakon 5 sati izlaganja tretmanima sadržavale više škroba u usporedbi s kontrolom te da je došlo do sinteze lipidnih kapljica.

Silver nanoparticles (AgNPs) are well known for their antimicrobial properties in many commercially available products, but due to their toxicity and reactivity, they can pose a risk to the aquatic environment. The model photosynthetic eukaryotic organism, Chlorella vulgaris, was used in this study. To evaluate the effect of AgNPs stabilized with polyvinylpyrrolidone (AgNP-PVP) and silver ions (AgNO3) on the microalgae, their growth, lipid peroxidation and catalase activity were measured upon their exposure to 0.5, 1.0, 1.5 and 2.0 ppm concentrations after 5, 24 and 48 hours in the modified liquid BBM nutrient medium. Additionally, the changes of pH, levels of dissolved oxygen and absorbance spectre in the range of 300-800 nm in the algae culture were analysed after the same period of treatment. Since stress conditions negatively affect ribulose bisphosphate carboxylase (Rubisco) protein synthesis, we used immunoblotting assay to analyse the expression levels of the large Rubisco chain to evaluate the fitness of algae upon treatment. After the treatment with AgNP-PVP or AgNO3 a significant dose-dependent decrease in cell number and an increase in dissolved oxygen and lipid peroxidation were observed. Furthermore, an increase in catalase activity was measured after all of the treatments, while an increase in pH was observed after 24 and 48 hours on treatments with 1.5 and 2.0 ppm of both AgNP-PVP and AgNO3. Visible light absorbance significantly decreased after the treatment with both AgNP-PVP and silver ions, with the decrease most noticeable in the characteristic chlorophyll a and b absorbance ranges. Immunoblotting revealed significant dose- dependent decrease in the levels of Rubisco large subunit after treatments with both AgNP-PVP and AgNO3.

Silver nanoparticles (AgNPs) have been used in a variety of industries including the medical, textile and agriculture sectors. Due to their tendency to agglomerate in various media, they are stabilised with various surface coatings like polyvinylpyrrolidone (PVP). As the use of AgNPs increases, so does the potential for their release into the environment. Since Chlorella vulgaris is one of the most ubiquitous microalgae inhabiting aquatic ecosystems, it is widely used as a model organism for assessing the impact of materials of anthropogenic origin, e.g. AgNPs, on aquatic habitats. To better evaluate the impact of AgNP- PVP on C. vulgaris, algae cultures were grown in a modified liquid BBM nutrient medium with and without the addition of 1% glucose. Once the algae reached the exponential growth phase, they were treated with 1.5 mg L-1 of either AgNP-PVP or ionic silver (AgNO3) (Fig.1). To evaluate the effects of AgNP-PVP and AgNO3, changes in the absorbance spectra (in the range 300-800 nm) of the algae cultures, and algae growth were analysed after 5 and 24 hours of exposure. Furthermore, to visualize ultrastructural changes after the treatments, algae cells were fixed with 1% glutaraldehyde in 50 mM cacodylate buffer (pH 7.2) for 1 h at +4 °C, washed twice and post-fixed with 1% osmium tetroxide in the same buffer for 1 h at +4 °C followed by 10 min wash in ice-cold water. After dehydration in a graded series of ethanol, the tissue was embedded in Spurr’s resin. Ultrathin sections were stained with 2% uranyl acetate and 2% lead citrate and examined using a FEI Morgagni 268D transmission electron microscope. After treatments with either AgNP-PVP or AgNO3, a significant dose-dependent decrease in cell number was observed when compared to the control sample. A significantly greater decrease was observed in cultures without added glucose compared to the cultures with added glucose. Similarly, a significant decrease was observed in the characteristic chlorophyll a and b absorbance ranges after treatments which is an indicator of toxic effect of the treatments on the algae. Again, a greater decrease was noted in the cultures without added glucose. Results from the TEM analyses (Fig.2.) showed that after 5 hours exposure in the nutrient medium without glucose, cells had undergone plasmolysis and had less starch, which can also be seen after 24 hours exposure (Fig. 2B-E). Furthermore, cell integrity was disturbed compared to the control sample, with greater disruption after exposure to AgNO3 (Fig. 2C and E). In comparison, after 5 hours of both treatments in a nutrient medium with 1% glucose, cells showed better integrity and contained more starch (Fig. 2G-J). However, after 5 hours of the same treatments supplemented with glucose, synthesis of lipid droplets had occurred, and which significantly progressed up to 24 hours (Fig. 2G-J). In conclusion, AgNP-PVP and AgNO3 showed toxic effects on the algae cultures, but with the addition of glucose to the nutrient medium, cells retained better integrity and suffered less ultrastructural damage. Decreased UV-vis absorbance and algae growth, combined with ultrastructural analyses, may indicate that AgNP- PVP and AgNO3 disrupt photosynthetic activity of the algae since the overall toxicity of both treatments was much lower in cultures grown in the nutrient medium with addition of glucose compared to those in the medium devoid of glucose.

Amino acids (AAs) attract attention for elucidating the role of proteins in biomineralization and the preparation of functionalized biomaterials. The influence that AAs exert on calcium phosphate (CaP) mineralization is still not completely understood, as contradictory results have been reported. In this paper, the influence of the addition of different classes of AAs, charged (L-aspartic acid, Asp, L-lysine, Lys), polar (L-asparagine, Asn, L-serine, Ser, L-tyrosine, Tyr), and non-polar (L-phenylalanine, Phe), on CaP growth in the presence of octacalcium phosphate (OCP) and calcium hydrogenphosphate dihydrate (DCPD) seeds was investigated. In control systems (without AAs), a calcium-deficient apatite (CaDHA) layer was formed on the surface of OCP, while a mixture of CaDHA and OCP in the form of spherical aggregates was formed on the surface of DCPD crystals. Charged and non-polar promoted, while polar AAs inhibited CaDHA formation on the OCP seeds. In the case of DCPD, Lys, Asp, and Phe promoted CaP formation, while the influence of other AAs was negligible. The most efficient promotor of precipitation in both cases was non-polar Phe. No significant influence of AAs on the composition and morphology of precipitates was observed. The obtained results are of interest for understanding biomineralization processes and additive controlled material synthesis.

The vast category of microplastics in the marine environment, encompassing among other aspects their persistence, degradation and impact on biota, has become an important topic of research. in spite of environmental health concerns, much work has yet to be done on understanding the potential roles of polymer sources, composition and particle sizes in causing adverse effects which have already been observed in a number of biota. the present study was aimed at adding to current knowledge by verifying if, and to what extent, embryogenesis in the sea urchin species Paracentrotus lividus is adversely affected by polystyrene and polymethylmethacrylate virgin microparticles over a size range 1-230 mu m and at concentrations of 0.1-10 mg L-1. Developing embryos which came in contact with the microplastics only after fertilisation did not display a significant increase of developmental defects. Unlike embryo exposures, when P. lividus sperm were exposed to the microplastics or their leachates, modest, yet significant effects were observed, both in terms of decreased fertilisation rate and increase of transmissible damage to offspring. Further, it was noted that larvae more readily ingested polymethylmethacrylate than polystyrene microparticles after 3 days which may represent a route for enhancing the toxicity of the former compared to the latter. Overall, these findings provide evidence for lesser sensitivity of P. lividus early life stages to microplastics compared to other urchins such as Sphaerechinus granularis. in turn, the more robust response of P. lividus highlights the importance of choosing an appropriate test species with the highest sensitivity when investigating mildly harmful materials., Croatian Science Foundation [IP-2018-01-5351]; Environment and Climate Change Canada, This work has been supported by the Croatian Science Foundation under grant number IP-2018-01-5351, and Environment and Climate Change Canada. the authors are grateful to Dr. Ozge Kozgus Guldu for DLS measurements.

Rare earth elements (REEs) are key constituents of modern technology and play important roles in various chemical and industrial applications. They also are increasingly used in agricultural and zootechnical applications, such as fertilizers and feed additives. Early applications of REEs in agriculture have originated in China over the past several decades with the objective of increasing crop productivity and improving livestock yield (e.g., egg production or piglet growth). Outside China, REE agricultural or zootechnical uses are not currently practiced. A number of peer-reviewed manuscripts have evaluated the adverse and the positive effects of some light REEs (lanthanum and cerium salts) or REE mixtures both in plant growth and in livestock yield. This information was never systematically evaluated from the growing body of scientific literature. The present review was designed to evaluate the available evidence for adverse and/or positive effects of REE exposures in plant and animal biota and the cellular/molecular evidence for the REE-associated effects. The overall information points to shifts from toxic to favorable effects in plant systems at lower REE concentrations (possibly suggesting hormesis). The available evidence for REE use as feed additives may suggest positive outcomes at certain doses but requires further investigations before extending this use for zootechnical purposes.

Silver nanoparticles (AgNPs) are used in a wide range of consumer products because of their excellent antimicrobial properties. AgNPs released into the environment are prone to transformations such as aggregation, oxidation, or dissolution so they are often stabilised by coatings that affect their physico-chemical properties and change their effect on living organisms. In this study we investigated the stability of polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) coated AgNPs in an exposure medium, as well as their effect on tobacco germination and early growth. AgNP-CTAB was found to be more stable in the solid Murashige and Skoog (MS) medium compared to AgNP-PVP. The uptake and accumulation of silver in seedlings was equally efficient after exposure to both types of AgNPs. However, AgNP-PVP induced only mild toxicity on seedlings growth, while AgNP-CTAB caused severe negative effects on all parameters, even compared to AgNO3. Moreover, CTAB coating itself exerted negative effects on growth. Cysteine addition generally alleviated AgNP-PVP-induced negative effects, while it failed to improve germination and growth parameters after exposure to AgNP-CTAB. These results suggest that the toxic effects of AgNP-PVP are mainly a consequence of release of Ag+ ions, while phytotoxicity of AgNP-CTAB can rather be ascribed to surface coating itself.

Alginate hydrogels are natural materials which can be used for biomedical purposes in order to trigger natural remineralization of damaged hard tissues. Mineralization of alginate hydrogels by using diverse protocols is extensively studied, with a goal of obtaining biocomposite materials having improved mechanical properties. The majority of the studies described in the literature are focused on the use of alginate in the form of beads, while alginate in bulk form has been more rarely studied. In this work, the influence of parameters, like phosphate concentration, type of media (water, HEPES and TRIS buffer) and pH (5.0, 7.4, 9.0), on gelation and mineralization of bulk alginate hydrogels (approx. 2 × 2 cm) was studied. Hydrogels were produced using semi- permeable membranes. In all experiments, calcium chloride solution was added as a mineralizing solution to the alginate dissolved in medium containing disodium phosphate, which simultaneously triggered gelation and mineralization of hydrogels. Hydrogels were mineralized for 5 days with daily exchange of mineralizing solution. Such hydrogels were characterized using a combination of infrared spectroscopy, powder X-ray diffraction and electron microscopy. The obtained results demonstrated that the media and pH have a profound influence on gelation and the stability of the hydrogels. Octacalcium phosphate was formed in all hydrogels except in TRIS buffer at pH = 9.0 where amorphous calcium phosphate (ACP) was formed. ACP was stabilized during the experiments, as well as during the extraction from the hydrogel. The obtained results point to a protocol suitable for fine-tuning the properties of the mineralized hydrogel, by a simple change of experimental conditions.

Spontaneous precipitation of CaCO3 polymorphs in the presence of selected amino acids (AA) has been investigated. The l -aspartic acid (Asp), l -lysine (Lys), l -asparagine (Asn), l -tyrosine (Tyr), l -phenylalanine (Phe), l -serine (Ser) and l -alanine (Ala) were selected because of different charge and polarity of their side chains at applied experimental conditions. The investigated AA are building units of soluble macromolecules, putatively responsible for biomineralization of molluscs’ exoskeletons. It was assumed that not only the acidic, but also the polar (hydrogen bonding) AA might contribute to macromolecules’ interactions with the mineral surfaces. The mineralogical composition, structure and morphology of precipitates formed in the presence of wide range of concentrations of AA have been determined by XRD, FT-IR and EPR spectroscopy, HPLC-MS and SEM. In the reference system, without AA addition, a mixture of typical calcite rhombohedral crystals and vaterite spherulites has been observed, while AA with negatively charged or polar side chains (Asp, Tyr, Lys, Asn, Ser) significantly changed the morphology, phase composition and crystal structure of the precipitates. The effects of nonpolar AA (Phe, Ala) on the structural and morphological properties of precipitates are less pronounced. The stronger impact observed for polar AA and particularly negatively charged Asp, may be correlated with the additional electrostatic interactions of side-chain groups with mineral surfaces.

International audience; Environmental stressors are assessed through methods that quantify their impacts on a wide range of metrics including species density, growth rates, reproduction, behaviour and physiology, as on host-pathogen interactions and immunocompetence. Environmental stress may induce additional sublethal effects, like mutations and epigenetic signatures affecting offspring via germline mediated transgenerational inheritance, shaping phenotypic plasticity, increasing disease susceptibility, tissue pathologies, changes in social behaviour and biological invasions.The growing diversity of pollutants released into aquatic environments requires the development of a reliable, standardised and 3R (replacement, reduction and refinement of animals in research) compliant in vitro toolbox. The tools have to be in line with REACH regulation 1907/2006/EC, aiming to improve strategies for potential ecotoxicological risks assessment and monitoring of chemicals threatening human health and aquatic environments.Aquatic invertebrates' adult stem cells (ASCs) are numerous and can be pluripotent, as illustrated by high regeneration ability documented in many of these taxa. This is of further importance as in many aquatic invertebrate taxa, ASCs are able to differentiate into germ cells. Here we propose that ASCs from key aquatic invertebrates may be harnessed for applicable and standardised new tests in ecotoxicology. As part of this approach, a battery of modern techniques and endpoints are proposed to be tested for their ability to correctly identify environmental stresses posed by emerging contaminants in aquatic environments.Consequently, we briefly describe the current status of the available toxicity testing and biota-based monitoring strategies in aquatic environmental ecotoxicology and highlight some of the associated open issues such as replicability, consistency and reliability in the outcomes, for understanding and assessing the impacts of various chemicals on organisms and on the entire aquatic environment. Following this, we describe the benefits of aquatic invertebrate ASC-based tools for better addressing ecotoxicological questions, along with the current obstacles and possible overhaul approaches.

The widespread use of rare earth elements (REEs) in a number of technological applications raises unanswered questions related to REE-associated adverse effects. We have previously reported on the multiple impact of some REEs on the early life stages of the sea urchin Paracentrotus lividus. The present investigation was to evaluate REE toxicity to early life stages in two unrelated sea urchin species, Sphaerechinus granularis and Arbacia lixula. The comparative toxicities were tested of seven REEs, namely yttrium, lanthanum, cerium, neodymium, samarium, europium and gadolinium as chloride salts at concentrations ranging from 10-7 to 10-4 M. The evaluated endpoints included developmental defects and cytogenetic anomalies in REE-exposed embryos/larvae, and decreased fertilization success and offspring damage following sperm exposure. The results showed different toxicity patterns for individual REEs that varied according to test species and to treatment protocol, thus showing toxicity scaling for the different REEs. Further, the observed effects were compared with those reported for P. lividus either following embryo or sperm exposures. S. granularis showed a significantly higher sensitivity both compared to A. lixula and to P. lividus. This study provides clear-cut evidence for distinct toxicity patterns among a series of REEs. The differences in species sensitivity at micromolar REE levels may warrant investigations on species susceptibility to impacts along polluted coasts.

The aim of this study is to contribute to understanding the mechanisms underlying the formation of biologically relevant minerals by comparing the properties of solid phases formed in calcium phosphate (CaP) or calcium carbonate (CaCO3) precipitation systems, at defined initial experimental conditions: supersaturation, constituent ions ratio, ionic strength, and/or presence of relevant inorganic ions. Thus, three systems of different chemical complexities were investigated: (a) system containing constituent ions, (b) system containing additional co-ions, and (c) system with higher ionic strength and addition of Mg2+. The respective precipitation diagrams were constructed, and supersaturation domains of different CaP and CaCO3 solid phases formation were identified. The obtained results may have implications not only for biomineralization and geochemistry, but also for materials science in general.

This work focuses on systematic research of spontaneous precipitation of calcium oxalate in model systems mimicking the chemical conditions typical for hyperoxaluria. For this purpose, model systems of three different complexities (simple, NaCl and artificial urine system) and two initial pH (pHi = 5.0 and pHi = 9.0) at 37 ºC are studied. In all investigated systems, dominant precipitation of calcium oxalate monohydrate (COM) is observed, except in artificial urine system at pHi = 9.0, ci(C2O42-) ≥ 6.0 mmol dm-3 and ci(Ca2+) ≥ 7.5 mmol dm-3 where precipitation of a mixture of calcium oxalate monohydrate and calcium oxalate dihydrate (COD) occurrs. The significant difference is mainly observed in COM crystal morphology. In a simple system, COM precipitates in a dendritic form, in NaCl system dendritic form and irregular shapes are found, while in the artificial urine, prismatic hexagonal and aggregated COM crystals precipitate.

Adverse environmental conditions in the Taranto area (southern Italy) were investigated in studies of air, marine sediment, and human health. The present study aimed at providing unprecedented information on soil pollution and toxicity in a set of sites around recognized pollution sources in the Taranto area, since previous studies were focused on marine or air pollution, or on human health effects. The investigated area included a steel foundry and a power plant, as well as some sites located in an adjacent neighborhood. Surface soil samples and urban dust were collected and submitted to inorganic and organic analyses and tested for toxicity in two invertebrate bioassay models; a sea urchin (Sphaerechinus granularis) and an annelid (Caenorhabditis elegans). Inorganic analysis was carried out using ICP-MS for elemental composition for a total of 34 elements, whose levels were evaluated as a function of bioassay data analyzed through principal component analysis (PCA). Other analyses included asbestos search by powder X-ray diffraction (PXRD) and organic analysis for polycyclic aromatic hydrocarbons (PAHs) and aliphatic compounds (C10-C40). Toxicity bioassays were carried out on a sea urchin (Sphaerechinus granularis), and an annelid (Caenorhabditis elegans). Sea urchin bioassays evaluated effects of topsoil or street dust sample exposures (0.1 to 0.5% dry wt/vol) on developing embryos and on sperm, and scored as (a) % developmental defects, (b) inhibition of fertilization success and offspring damage, and (c) frequencies of mitotic aberrations. C. elegans mortality assay displayed significant toxicity associated with soil samples. The overall effects of samples showed very high toxicity at four out of nine sites. These effects were consistent with the highest levels measured for metals and PAHs. Further studies of health effects related to dust exposures in residential areas are warranted. Graphical abstract ᅟ.

Calcium sulfate (CS) is a reasonable alternative to autogenous dental bone graft and is used as a bone filler or for the treatment of bone defects. Medical grade CS must be sterilized, usually by gamma-irradiation. In this study the structures of CS polymorphs, calcium sulfate dihydrate and calcium sulfate hemihydrate, have been investigated with electron paramagnetic resonance (EPR) spectroscopy, X-ray diffraction, thermogravimetric analyses and infrared spectroscopy. The influences of saline and artificial saliva on gamma-induced radical concentrations have been monitored.

Chitin, a bioactive, antibacterial and biodegradable polymer is commonly utilized by diverse marine organisms as the main scaffold material during biomineralization. Due to its properties, chitin is also of interest as a component of organo-inorganic composites for diverse biomedical applications. In this study, chitinous fibers isolated from the cuttlebone of the common cuttlefish (Sepia officinalis, L.) are characterized and evaluated for use as an integral part of mineralized hydrogels for biomedical applications. Since marine organisms use calcium carbonates (CaCO3), while vertebrates use calcium phosphates (CaP) as the main inorganic hard tissue components, and both minerals are used in hard tissue engineering, they were compared to determine which composite is potentially a better biomaterial. Hydrogel mineralization was conducted by subsequent dipping into cationic and anionic reactant solutions, resulting in the formation of a CaCO3 or CaP coating that penetrated into the hydrogel. Obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), rheology, swelling tests and simple compression. The results indicate that β-chitin can be used for the preparation of moldable hydrogels that are easily mineralized. Mineralized hydrogels have higher elasticity than non- mineralized ones while swelling is better if the extent of mineralization is lower. Further optimization of the hydrogels composition could improve their stress response and Young’s modulus, where the current hydrogel with a higher extent of CaP mineralization excels in comparison to all other investigated composites.

WOS: 000497259100061, PubMed: 31629182, Two microplastic sets, polystyrene (PS) and polymethyl methacrylate (PMMA), were tested for adverse effects on early life stages of Sphaerechinus granularis sea urchins. Microparticulate PS (10, 80 and 230 mu m diameter) and PMMA (10 and 50 mu m diameter) were tested on developing S. granularis embryos from 10 min post-fertilisation (p-f) to the pluteus larval stage (72 h p-f), at concentrations ranging from 0.1 to 5 mg L-1. Both PS and PMMA exposures resulted in significant concentration-related increase of developmental defects and of microplastic uptake in plutei. Moreover, embryo exposures to PS and PMMA (5 and 50 mg L-1) from 10 min to 5 h p-f resulted in a significant increase of cytogenetic abnormalities, expressed as significantly increased mitotic aberrations, while mitotoxicity (as % embryos lacking active mitoses) was observed in embryos exposed to PS, though not to PMMA. When S. granularis sperm suspensions were exposed for 10 min to PS or to PMMA (0.1-5 mg L-1), a significant decrease of fertilisation success was observed following sperm exposure to 0.1 mg L-1 PS, though not to higher PS concentrations nor to PMMA. Sperm pretreatment, however, resulted in significant offspring damage, as excess developmental defects in plutei, both following sperm exposure to PS and PMMA, thus suggesting transmissible damage from sperm pronuclei to the offspring. the overall results point to relevant developmental, cytogenetic and genotoxic effects of PS and PMMA microplastics to S. granularis early life stages, warranting further investigations of other microplastics and other target biota., Croatian Science Foundation [IP-2018-01-5351]; Environment and Climate Change Canada, This work has been supported by the Croatian Science Foundation under project IP-2018-01-5351. Financial support from Environment and Climate Change Canada is also gratefully acknowledged. Declarations of conflict: none.

Amorphous calcium carbonate (ACC) and calcium phosphate (ACP) increasingly attract attention as initial solid phases in vertebrate and invertebrate hard tissue formation, as well as in materials science as a possible new synthetic route for advanced materials preparation. Although much is known about these two amorphous phases and similarities in the mechanisms of their formation are recognized, no attempt has been made to investigate their formation under defined and comparable initial experimental conditions viz supersaturation, constituent ions ratio, ionic strength and presence of relevant inorganic additives. In this paper, the formation of ACC and ACP in three model precipitation systems of increased chemical complexity were investigated: (a) systems containing constituent ions, (b) systems containing additional co-ions, and (c) systems with higher ionic strength and addition of Mg2+. The results have shown that ACP is more stable and was formed at lower relative supersaturations in comparison to ACC. The precipitation domain of both phases expanded with increasing complexity of precipitation systems, with the ACP precipitation domains always being larger than that of ACC. In addition to stability, the presence of inorganic ions, especially Mg2+, influences the composition of both amorphous phases. The obtained results indicate that general similarity between ACC and ACP exists, but it could also be concluded that similar chemical environment in which they form not necessary lead to similar structural properties.

Heavy rare earth elements (HREEs) were tested for adverse effects to early life stages of the sea urchin Sphaerechinus granularis. Embryos were exposed to analytically measured HREE concentrations ranging from 10-7 to 10-5 M. No significant developmental defects (DD) increases were observed in embryos exposed to 10-7 M HREEs, whereas 10-5 M HREEs resulted in significant DD increase up to 96% for HoCl3 vs. 14% in controls. Embryos exposed to 10-6 M HREEs showed the highest DD frequency in embryos exposed to 10-6 M DyCl3 and HoCl3. Cytogenetic analysis of HREE-exposed embryos revealed a significant decrease in mitotic activity, with increases in mitotic aberrations. When S. granularis sperm were exposed to HREEs, a significant decrease of fertilization success was observed, with the offspring of sperm exposed to 10-5 M GdCl3 and LuCl3 showing significant DD increases. The results warrant investigations on HREEs in other test systems, and on REE-containing complex mixtures.

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Marine biotoxins are widespread in the environment and impact human health via contaminated shellfish, causing diarrhetic, amnesic, paralytic, or neurotoxic poisoning. In spite of this, methods for determining if poisoning has occurred are limited. We show the development of a simple and sensitive luminescence resonance energy transfer (LRET)-based concept which allows the detection of anti-okadaic acid rabbit polyclonal IgG (mouse monoclonal IgG1) using functionalized lanthanide-based nanoparticles. Upon UV excitation, the functionalized nanoparticles were shown to undergo LRET with fluorophore-labeled anti-okadaic acid antibodies which had been captured and bound by okadaic acid-decorated nanoparticles. The linear dependence of fluorescence emission intensity with antigen−antibody binding events was recorded in the nanomolar to micromolar range, while essentially no LRET signal was detected in the absence of antibody. These results may find applications in new, cheap, and robust sensors for detecting not only immune responses to biotoxins but also a wide range of biomolecules based on antigen−antibody recognition systems. Further, as the system is based on solution chemistry it may be sufficiently simple and versatile to be applied at point-of-care.

In parallel with the growing use of nanoparticle-containing products, their release into the environment over the coming years is expected to increase significantly. With many large population centers located in near-coastal areas, and increasing evidence that various nanoparticles may be toxic to a range of organisms, biota in estuarine and coastal waters may be particularly vulnerable. While size effects may be important in cases, silver nanoparticles have been found to be toxic in large part due to their release of silver ions. However, there is relatively little data available on how nanoparticle coatings can affect silver ion release in estuarine or marine waters. We have found that albumin, as a model for biocorona-forming macromolecules which nanoparticles may encounter in wastewater streams, stabilizes silver colloids from agglomeration in high salinity marine waters by electrosteric repulsion for long time periods. A minimum mass ratio of about 130 for albumin:silver nanoparticles (40 nm) was required for stable dispersion in seawater. Increasing albumin concentration was also found to reduce dissolution of nanoparticles in seawater with up to 3.3 times lower concentrations of silver ions noted. Persistent colloids and slow sustained ion release may have important consequences for biota in these environmental compartments.

A systematic investigation of non-phosphorus containing glycolipids (GL) was conducted in the northern Adriatic Sea during two years at two stations with different nutrient loads. GL concentration varied both spatially and temporally, with values of 1.1-21.5 g/L and 0.4-44.7 g/L in the particulate and the dissolved fraction, respectively. The highest concentrations were measured during summer in surface waters and at the more oligotrophic station, where GL yields (% of total lipids) were often higher than 20% and 50% in the particulate and dissolved fractions, respectively. To obtain more insight into factors governing GL accumulation autotrophic plankton community structure (pico-, nano- and microplankton fractions), chlorophyll a, heterotrophic bacteria and nutrient concentrations were measured together with hydrographic parameters and sunlight intensity. During the investigated period smaller autotrophic plankton cells (pico- and followed by nanoplankton) prevailed in abundance over larger cells (microplankton), which were found in large numbers in freshened surface samples. Several major findings resulted from the study. Firstly, during PO4 limitation, particularly at the oligotrophic station, enhanced glycolipid instead of phospholipid accumulation takes place, representing an effective phosphate-conserving mechanism. Secondly, results suggest that at seawater temperatures >19ºC autotrophic plankton considerably accumulate GL, probably to achieve thermal stability. Thirdly, high sunlight intensities seem to influence increased GL accumulation ; GL possibly plays a role in cell mechanisms that prevent/mitigate photooxidation. And finally, substantial accumulation of GL detected in the dissolved fraction could be related to the fact that GL do not contain biologically relevant elements, like phosphorus, which makes them an unattractive substrate for enzyme activity. Therefore, substantial portion of CO2 could be removed from the atmosphere in P-limited regions during summer via its capture by plankton and conversion to GL.

A rare bronze sculpture of the male athlete Apoxyomenos, dating from about the 2nd century BCE, was found submerged in the Adriatic Sea off the Croatian coast, in 1998. The influence of this specific artificial surface on the crystal phase of encrusted calcareous structures of biomineralizing marine organisms was probed. ICP-AES analysis showed all samples to have a high metal content, with the specific metals and their concentrations being consistent with the sculpture as the source rather than normal seawater. No metal-based crystalline phases were found by powder X-ray diffraction apart from the presence of iron and copper hydroxides in one sample that showed a distinctly green coloration. XRD analysis indicated that calcite, magnesium calcite and aragonite were the dominant phases in all cases, with minor or trace phases of albite, microcline and mineral quartz. The phase compositions of these biomineralized structures were significantly different from those of the same organisms living in putatively unpolluted environments. The accumulation of non-native metals in the calcareous structures of these organisms and the unusual phase compositions of the latter suggest metal-induced changes to the biological pathways controlling the transport of calcium and magnesium and incorporation of heavy metals at inorganic matrix growth sites.

During 2004 and 2006, alkaline phosphatase activity (APA) was measured in the northern Adriatic to establish, if it is an important mechanism for phosphorus recycling in this area, which is poor in orthophosphate (PO4). From May to September, in conditions of exhausted PO4, microbes in upper waters induced high APA (0.41 to 5.55 μ mol l– 1 h– 1) to obtain phosphorus from the dissolved organic pool. The highest APA was found during spring and summer freshets due to the strongly deficient PO4 versus inorganic nitrogen supply from the Po River. During the summer months, APA was lower yet still important for phosphorus recycling. In these months, the low Po River nitrogen supply resulted in lower microbial biomass and, consequently, lower APA. From October to December, APA in upper waters was low (

With the ever growing use of nanoparticles in a broad range of industrial and consumer applications there is increasing likelihood that such nanoparticles will enter the aquatic environment and be transported through freshwater systems, eventually reaching estuarine or marine waters. Due to silver's known antimicrobial properties and widespread use of silver nanoparticles (AgNP), their environmental fate and impact is therefore of particular concern. In this context we have investigated the species-specific effects of low concentrations of 60 nm AgNP on embryonal development in Mediterranean sea urchins Arbacia lixula , Paracentrotus lividus and Sphaerechinus granularis . The sensitivity of urchin embryos was tested by exposing embryos to nanoparticle concentrations in the 1–100 μg L −1 range, with times of exposure varying from 30 min to 24 h (1 h–48 h for S. granularis ) post-fertilisation which corresponded with fertilized egg, 4 cell, blastula and gastrula development phases. The most sensitive species to AgNP was A. lixula with significant modulation of embryonal development at the lowest AgNP concentrations of 1–10 μg L −1 with high numbers of malformed embryos or arrested development. The greatest impact on development was noted for those embryos first exposed to nanoparticles at 6 and 24 h post fertilisation. For P. lividus , similar effects were noted at higher concentrations of 50 μg L −1 and 100 μg L −1 for all times of first exposure. The S. granularis embryos indicated a moderate AgNP impact, and significant developmental abnormalities were recorded in the concentration range of 10–50 μg L −1 . As later post-fertilisation exposure times to AgNP caused greater developmental changes in spite of a shorter total exposure time led us to postulate on additional mechanisms of AgNP toxicity. The results herein indicate that toxic effects of AgNP are species-specific. The moment at which embryos first encounter AgNP is also shown to be an important factor in the development of abnormalities, and future applications of the sea urchin embryo development test for nanoparticle toxicity testing should carefully address the specific phase of development of embryos when nanoparticles are first introduced.

With the increasing movement away from the mouse bioassay for the detection of toxins in commercially harvested shellfish, there is a growing demand for the development of new and potentially field-deployable tests in its place. In this direction we report the development of a simple and sensitive nanoparticle-based luminescence technique for the detection of the marine biotoxin okadaic acid. Photoluminescent lanthanide nanoparticles were conjugated with fluorophore-labelled anti-okadaic acid antibodies which, upon binding to okadaic acid, gave rise to luminescence resonance energy transfer from the nanoparticle to the organic fluorophore dye deriving from a reduction in distance between the two. The intensity ratio of the fluorophore: nanoparticle emission peaks was found to correlate with okadaic acid concentration, and the sensor showed a linear response in the 0.37-3.97 μM okadaic acid range with a limit of detection of 0.25 μM. This work may have important implications for the development of new, cheap, and versatile biosensors for a range of biomolecules and that are sufficiently simple to be applied in the field or at point-of-care.

A unique supercritical fluid inclusion-phase technique has been developed to embed silicon nanowires, with size monodispersed diameters, within the pores of mesoporous silica hosts. These nanocomposite materials displayed quite intense room temperature ultraviolet and visible photoluminescence (PL), and the emission wavelength maximum was found to be dependent on the diameter of the encased nanowires. This previously unobserved wavelength dependence of the ultraviolet PL with decreasing nanowire size is explained using a continuum strain model resulting from confinement of the wires within the host lattice.

The importance of bacterial, phytoplankton and dissolved alkaline phosphatase activity (APA) in the northern Adriatic was investigated during 2006. In surface waters total APA increased from early spring (0.07-0.08 micromol l(-1) h(-1)) to late spring (up to 4.64 micromol l(-1) h(-1)) and remained relatively high during the summer (0.46-0.71 micromol l(-1) h(-1)), due to an increase in specific phytoplankton (up to 30 nmol microg C(-1) h(-1)) and bacterial APA (up to 17.11 nmol microg C(-1) h(-1)). Activity of free enzymes was not important. During late spring and summer both communities exploited dissolved organic phosphorus although, taking into account biomass, phytoplankton activity usually dominated over bacterial activity. In autumn an extra P supply from deeper waters drastically reduced phytoplankton APA, though not bacterial APA, in upper waters. Probably in these months bacteria that were degrading phytoplankton produced organic matter were P limited. In deeper waters APA was low and mainly due to the activity of free enzymes.

1. Based on the inclusion of macroalgae in the European Union Water Framework Directive as quality elements for the evaluation of the ecological status of coastal waters, the suitability of one (Ecological Evaluation Index, EEI) of several previously proposed evaluation methods in the particular ecological conditions of the northern Adriatic Sea was tested. 2. The EEI was assessed for 10 locations (polluted and putatively pristine) scattered along 60 km of the western Istrian coast. The sampling was performed seasonally at 1 and 3 m depth by destructive (determination of species cover and biomass) and non-destructive (determination of species coverage using digital photography) methods. 3. When assessed at 1 m depth the spatial scale weighted EEI for the west Istrian coast was 8.1, corresponding to an ecological status class (ESC) value of high. However, data for 3 m depth gave a spatial EEI of 6.72 which corresponds to an ESC value of good. Regressions of the ratio of ecological state group I (ESG I, i.e. thick leathery, calcareous and crustose species) over total algal abundance with the pollution gradient (obtained using principal components analysis (PCA) ordination of environmental variables) were significant at 3 m but not at 1 m depth. This was due to the high abundance of ESG I macroalgae Corallina elongata and Cystoseira compressa at 1 m depth at polluted stations. Similar regressions were obtained using cover, biomass and coverage. 4. It is concluded that the EEI method may be suitable for the classification of coastal waters in the northern Adriatic only in certain cases. A better assessment of ecological status using this method would require more realistic estimations based on the inclusion of data from several sampling depths. As all three abundance measures (cover, biomass, coverage) gave similar results, coverage (using digital photography) is suggested as being a preferred measure owing to the rapidity of sampling at several depths and less time-consuming laboratory work. Copyright © 2008 John Wiley & Sons, Ltd.

[1] CTD data were collected weekly during 20 cruises from May to September 2003 over a 19 station grid in a coastal region of the northeastern Adriatic Sea as part of the Adriatic Sea Integrated Coastal Areas and River Basin Management System Pilot Project (ADRICOSM). Relative geostrophic velocities indicated fine scale circulation patterns in the area consisting of two pronounced circulation cells, of cyclonic and anticyclonic character, and that were present in the area for most of the investigated period. These motions were induced primarily by spatial variations in the temperature field and may be strengthened during episodes of very strong northeasterly bora wind, when the investigated region is not heated (cooled) uniformly.

Triblock copolymer templated aluminosilicate mesoporous thin films are formed without loss in long-range order using magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) -optimised selective alkoxide hydrolysis. The judicious incorporation of aluminium into the silica matrix greatly enhances substrate adhesion, chemical resistance, mechanical stability and thermal stability. Compared to silica analogues, the optimised mixed alkoxide mesoporous films demonstrate increases in modulus of hardness (x 4), cohesive strengths (x 2) and resistance to thermal cracking (x 2). No-loss in long-range mesophasic order accruing to heteroatom incorporation is observed. The pore channels in the hexagonal film are unidirectionally aligned and reorientation of the axis is shown through manipulation of preparation and processing conditions. Perpendicularly aligned pores, formed under rapid solvent evaporation conditions on conducting substrates, are used as nanoscale support matrices to host supercritical fluid-deposited semiconductor nanowires. Atomic force microscopy in conducting mode demonstrates continuous electrical contact from mesoporous thin-film surface through aligned nanowires to the conducting substrate

Mucilage events have been documented several times during the last two centuries in the northern Adriatic Sea (NA), but their frequency has significantly increased during the last 15 years (since 1988). The shallow NA is strongly influenced by meteorological conditions and by freshwater discharges, mainly from the Po River. Consequently, the oceanographic properties of water masses change considerably during the seasons and from year-to year. In this work, the main meteorological and oceanographic conditions in the NA during the period June 1999-July 2002 are described and related to the mucilage phenomenon (formation of large organic aggregates and gelatinous surface layers). Approximately monthly cruises along three transects in the NA were performed. Remarkable meteorological situations were selected from large-scale ECMWF analyses and from the Local Analysis and Prediction System (LAPS ; Emilia Romagna Meteorological Service), while sea conditions were analysed from the Wave Adriatic Model (WAM) output. Data for several meteorological stations in the region were used. Average seasonal cycles of sea temperature and salinity simulated with statistical models, based on historical data collected in the NA since 1972, were used to define thermal and haline anomalies. The monthly anomaly variability of maximum and minimum air temperatures, and rainfall (amount and number of rain days) did not appear to be relevant for the mucilage phenomenon outbreak. However, the thermohaline gradients in the region were more developed in 2002, and, even if at some lower intensity, in 2000, i.e. proportionally to the intensity and duration of the mucilage events, compared to 2001 (short living event) and 1999 (no event). These more pronounced gradients were due to a combination of several unusual conditions: sharp heating of the sea surface in May-June, domination of eastwards transport of freshened waters formed in the Po Delta area, and intrusion of very high salinity intermediate waters, originated in the Cretan Sea and Levantine Basin. Moreover, in winter of both 2000 and 2002 very dense and cold water formed and remained in the bottom layer up to spring, contributing to increase the stratification degree of the water column. The duration of the mucilage events and 3 their spatial distribution in the region depend strongly on meteorological changes. Recurrent anticyclonic conditions, characterized by low wind and calm sea, favour extended events in time (up two months in 2002). In contrast, unusual bad weather, particularly due to strong "bora" wind, can be determining in sharp decay of the event (e.g. in July 2000).

A combined transmission electron microscopy-scanning tunneling microscopy (TEM-STM) technique has been used to investigate the force interactions of silicon and germanium nanowires with gold electrodes. The I(V) data obtained typically show linear behavior between the gold electrode and silicon nanowires at all contact points, whereas the linearity of I(V) curves obtained for germanium nanowires were dependent on the point of contact. Bistable silicon and germanium nanowire-based nanoelectromechanical programmable read-only memory (NEMPROM) devices were demonstrated by TEM-STM. These nonvolatile NEMPROM devices have switching potentials as low as 1 V and are highly stable making them ideal candidates for low-leakage electronic devices. (C) 2004 American Institute of Physics. (DOI:10.1063/1.1751622)

Metallic nanowires of cobalt, copper, and iron oxide magnetite (Fe3O4) have been synthesized within the pores of mesoporous silica using a supercritical fluid inclusion technique. The mesoporous matrix provides a means of producing a high density of stable, hexagonally ordered arrays of highly crystalline nanowires. The formation of the metal and metal oxide nanowires within the silica mesopores was confirmed by transmission electron microscopy (TEM), N2 adsorption experiments, and powder X-ray diffraction (PXRD). The mechanism of nanowire formation within the mesopores appears to occur through the initial binding and coating of the pore walls with the metal atoms to form tubelike structures within the mesoporous template. The thickness of these tubes subsequently increases with further metal deposition until nanowires are formed. Additionally, the crystal structure of the cobalt nanowires formed within the mesoporous template can be readily changed by manipulating the density of the supercritical fluid phase.

In the near future physical and economic constraints are expected to limit the continued miniaturisation of electronic and optical devices using current "top-down" lithography-based methods. Consequently, nonlithographic methods for synthesising and organising materials on the nanometre scale are required. In response to these technological needs a number of research groups are developing new supercritical fluids methodologies to synthesise and self-assemble "building blocks" of nanomaterials, from the "bottom-up", into structurally complex device architectures. This concept paper highlights some of the recent advances in the synthesis of metal and semiconductor nanoparticles and nanowires by using supercritical fluids. In addition, we describe an efficient supercritical fluid approach for constructing ordered arrays of metal and semiconductor nanowires within mesoporous silica templates.