Acute stress-induced (takotsubo) cardiomyopathy has a dramatic clinical presentation, mimicking an acute myocardial infarction and is triggered by intense emotional or physical stress. In this paper, ...we review the current state of knowledge of the mechanistic physiology underlying the left ventricular ballooning. The pathophysiology of the recovery from this acute heart failure syndrome is presented. The short-term and long-term outlook puts this new syndrome on a different perspective compared with recently held views. Current knowledge on susceptibility and predisposition already define distinctive characteristics of patients with takotsubo compared with myocardial infarction. Gaps in knowledge and future directions of research are identified in order to best direct efforts for identifying specific therapies for this condition, in the acute setting, to mitigate postacute symptoms or to prevent recurrences, none of which exist.
Traditionally 4xxx casting alloys are used for the additive manufacturing of structurally optimised lightweight parts in space, aerospace and automotive. However, for such applications there is a ...need for hardenable high-strength Al-alloys exceeding the properties of the 4xxx alloys family. The study analyses the hardness response of different heat treatment temperatures and hold durations applied to a Sc- and Zr-modified Al-Mg (5xxx-) alloy (Scalmalloy®) processed by Selective Laser Melting, and compares the mechanical properties and microstructure in the as-processed and annealed condition, and these properties are clearly related to the very fine grained microstructure. The results show that the static mechanical properties are exceptionally good with Rm-values exceeding 500MPa along with almost no build-orientation related anisotropic effects, and a high ductility even in the heat treated condition. These properties are clearly related to the very fine grained material, along with the good hardenability of the alloy. The stress-strain curves show the typical Portevin-Le-Chatelier (PLC) effect as known for other 5xxx alloys. Due to significant grain boundary pinning by different particles the very fine-grained bi-modal microstructure originating from the SLM-process can be maintained even in the heat treated condition, and only a HIP treatment leads to local grain growth only in coarser grained regions.
Nanoplastic debris, resulted from runoff and weathering breakdown of macro- and microplastics, represents an emerging concern for marine ecosystems. The aim of the present study was to investigate ...disposition and toxicity of polystyrene nanoparticles (NPs) in early development of sea urchin embryos (Paracentrotus lividus). NPs with two different surface charges where chosen, carboxylated (PS-COOH) and amine (PS-NH2) polystyrene, the latter being a less common variant, known to induce cell death in several in vitro cell systems. NPs stability in natural seawater (NSW) was measured while disposition and embryotoxicity were monitored within 48 h of postfertilization (hpf). Modulation of genes involved in cellular stress response (cas8, 14-3-3ε, p-38 MAPK, Abcb1, Abcc5) was investigated. PS-COOH forms microaggregates (PDI > 0.4) in NSW, whereas PS-NH2 results are better dispersed (89 ± 2 nm) initially, though they also aggregated partially with time. Their respectively anionic and cationic nature was confirmed by ζ-potential measurements. No embryotoxicity was observed for PS-COOH up to 50 μg mL–1 whereas PS-NH2 caused severe developmental defects (EC50 3.85 μg mL–1 24 hpf and EC50 2.61 μg mL–1 48 hpf). PS-COOH accumulated inside embryo’s digestive tract while PS-NH2 were more dispersed. Abcb1 gene resulted up-regulated at 48 hpf by PS-COOH whereas PS-NH2 induced cas8 gene at 24 hpf, suggesting an apoptotic pathway. In line with the results obtained with the same PS NPs in several human cell lines, also in sea urchin embryos, differences in surface charges and aggregation in seawater strongly affect their embryotoxicity.
Selective Laser Melting (SLM) is an additive manufacturing technology that offers significant potential for lightweight applications in space, aerospace, and automotive industries as well as in ...mechanical engineering. Structural aluminium alloys are therefore of special interest. Scalmalloy® is a scandium-modified Al-Mg alloy which displays exceptional properties when processed by SLM. These properties are predominately related to a generally very fine grained microstructure. However, the fine grained microstructure interspersed with coarser grained regions. Microstructural analyses indicate that the temperature regime and the particle precipitation behaviour are responsible for the duplex grain structures. In melt pool areas close to the pool base, numerous Al3(Sc,Zr), Al-Mg-oxides and mixed particles act as nuclei for Al matrix solidification, leading to the formation of a very fine grained microstructure. In hot melt pool areas with T>800°C the majority of particles dissolve and growth of coarse columnar grains takes place. Better understanding of the formation mechanisms for these two distinct different structures will help pave the way towards newly designed alloy compositions for the SLM process.
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•Comprehensive description of the microstructure.•Additive manufactured Scandium and Zirconium modified AlMg alloys exhibit a bi-modal grain size distribution.•The formation fine-grained microstructure is closely related to the presence of intermetallic particles in the melt pool.•Precipitate survival is affected by local temperature distribution in the melt-pool.
Abstract
We present reverberation mapping results from the first year of combined spectroscopic and photometric observations of the Sloan Digital Sky Survey Reverberation Mapping Project. We ...successfully recover reverberation time delays between the
g
+
i
band emission and the broad H
β
emission line for a total of 44 quasars, and for the broad H
α
emission line in 18 quasars. Time delays are computed using the
JAVELIN
and
CREAM
software and the traditional interpolated cross-correlation function (ICCF): using well-defined criteria, we report measurements of 32 H
β
and 13 H
α
lags with
JAVELIN
, 42 H
β
and 17 H
α
lags with
CREAM
, and 16 H
β
and eight H
α
lags with the ICCF. Lag values are generally consistent among the three methods, though we typically measure smaller uncertainties with
JAVELIN
and
CREAM
than with the ICCF, given the more physically motivated light curve interpolation and more robust statistical modeling of the former two methods. The median redshift of our H
β
-detected sample of quasars is 0.53, significantly higher than that of the previous reverberation mapping sample. We find that in most objects, the time delay of the H
α
emission is consistent with or slightly longer than that of H
β
. We measure black hole masses using our measured time delays and line widths for these quasars. These black hole mass measurements are mostly consistent with expectations based on the local
–
relationship, and are also consistent with single-epoch black hole mass measurements. This work increases the current sample size of reverberation-mapped active galaxies by about two-thirds and represents the first large sample of reverberation mapping observations beyond the local universe (
z
< 0.3).
•Long-term lethality test using Artemia franciscana discriminates PS NP toxicity.•Surface chemistry determines nanoplastics behaviour and impact on marine plankton.•PS-COOH are adsorbed on the ...microalgae and accumulated in brine shrimp.•PS-NH2 inhibits microalgal growth and causes mortality in brine shrimp larvae.•clap up-regulation indicates physiological alterations in brine shrimp larvae.
Plastic pollution has been globally recognized as a critical issue for marine ecosystems and nanoplastics constitute one of the last unexplored areas to understand the magnitude of this threat. However, current difficulties in sampling and identifying nano-sized debris make hard to assess their occurrence in marine environment. Polystyrene nanoparticles (PS NPs) are largely used as nanoplastics in ecotoxicological studies and although acute exposures have been already investigated, long-term toxicity on marine organisms is unknown. Our study aims at evaluating the effects of 40nm PS anionic carboxylated (PS-COOH) and 50nm cationic amino-modified (PS-NH2) NPs in two planktonic species, the green microalga Dunaliella tertiolecta and the brine shrimp Artemia franciscana, respectively prey and predator. PS NP behaviour in exposure media was determined through DLS, while their toxicity to microalgae and brine shrimps evaluated through 72h growth inhibition test and 14 d long-term toxicity test respectively. Moreover, the expression of target genes (i.e. clap and cstb), having a role in brine shrimp larval growth and molting, was measured in 48h brine shrimp larvae. A different behaviour of the two PS NPs in exposure media as well as diverse toxicity to the two planktonic species was observed. PS-COOH formed micro-scale aggregates (Z-Average>1μm) and did not affect the growth of microalgae up to 50μg/ml or that of brine shrimps up to 10μg/ml. However, these negatively charged NPs were adsorbed on microalgae and accumulated (and excreted) in brine shrimps, suggesting a potential trophic transfer from prey to predator. On the opposite, PS-NH2-formed nano-scale aggregates (Z-Average<200nm), caused inhibition of algal growth (EC50=12.97μg/ml) and mortality in brine shrimps at 14 d (LC50=0.83μg/ml). Moreover, 1μg/ml PS-NH2 significantly induced clap and cstb genes, explaining the physiological alterations (e.g. increase in molting) previously observed in 48h larvae, but also suggesting an apoptotic pathway triggered by cathepsin L-like protease in brine shrimps upon PS-NH2 exposure. These findings provide a first insight into long-term toxicity of nanoplastics to marine plankton, underlining the role of the surface chemistry in determining the behaviour and effects of PS NPs, in terms of adsorption, growth inhibition, accumulation, gene modulation and mortality. The use of long-term end-point has been identified as valuable tool for assessing the impact of nanoplastics on marine planktonic species, being more predictable of real exposure scenarios for risk assessment purposes.
•Low level of influence of laser scan speed in SLM on the microstructure and grain size in Sc- and Zr- modified AlMg alloys.•Precipitation of Al3(Scx Zr1-x) particles occurs at low laser scan speeds. ...At high scan speeds Sc and Zr is in solid solution.•Zener pinning by Al3Sc particles and further features stabilize the microstructure against grain growth AM-processing.
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Additive processing via Selective Laser Melting (SLM) of Sc- and Zr-modified Al-Mg alloys (commercially known as Scalmalloy®) provides significant advantages over traditional 4xxx casting alloys. This is due to the high strength and ductility at very low mechanical anisotropy, which is a result of the alloys' very fine-grained microstructure combined with weak texture in the build-up direction. Next to their advantageous mechanical properties, the reliability of alloys processed by additive manufacturing is of great importance. Variations in microstructural features due to the use of different in processing parameters (e.g. laser scan speed) are well known for traditional alloys. This study analyses the influence of varying laser scan speeds on the static mechanical properties of SLM-processed Scalmalloy®, and discusses the evolving microstructure and precipitation of nm-sized Al3Sc particles at the correspondingly different energy inputs. It is found that by about doubling the laser scan speed the peak grain sizes in the fine-grained regions decrease from 1.1μm to 600nm, whereas in the coarse grained region almost no influence is observed. Al3Sc particles are only precipitated during processing at low scan speeds due to the corresponding high laser energy input, or by the intrinsic heat treatment from subsequent layers being built.
Polymeric nanoparticles can reach the marine environment from different sources as weathering of plastic debris and nanowaste. Nevertheless, few data are available on their fate and impact on marine ...biota. Polystyrene nanoparticles (PS NPs) can be considered as a model for studying the effects of nanoplastics in marine organisms: recent data on amino-modified PS NPs (PS-NH2) toxicity in sea urchin embryos underlined that marine invertebrates can be biological targets of nanoplastics. Cationic PS NPs have been shown to be toxic to mammalian cells, where they can induce apoptotic processes; however, no information is available on their effects and mechanisms of action in the cells of marine organisms. In this work, the effects of 50 nm PS-NH2 were investigated in the hemocytes of the marine bivalve Mytilus galloprovincialis. Hemocytes were exposed to different concentrations (1, 5, 50 μg/ml) of PS-NH2 suspension in ASW. Clear signs of cytoxicity were evident only at the highest concentrations (50 μg/ml). On the other hand, a dose dependent decrease in phagocytic activity and increase in lysozyme activity were observed. PS-NH2 NPs also stimulated increase in extracellular ROS (reactive oxygen species) and NO (nitric oxide) production, with maximal effects at lower concentrations. Moreover, at the highest concentration tested, PS-NH2 NPs induced apoptotic process, as evaluated by Flow cytometry (Annexin V binding and mitochondrial parameters). The results demonstrate that in marine invertebrates the immune function can represent a significant target for PS-NPs. Moreover, in Mytilus hemocytes, PS-NH2 NPs can act through mechanisms similar to those observed in mammalian cells. Further research is necessary on specific mechanisms of toxicity and cellular uptake of nanoplastics in order to assess their impact on marine biota.
•Nanoplastics-NPs from plastic debris in oceans may become a threat to marine biota.•Cationic polystyrene NPs showed toxicity in mammalian cells and sea urchin embryos.•The in vitro effects of PS-NH2 were investigated in Mytilus hemocytes.•PS-NH2 affected several immune parameters and induced pre-apoptotic processes.•The immune function represents a significant target for PS-NPs In marine invertebrates.
Aims
This study focused on comparing the phylogenetic composition and functional potential of the intestinal microbiome of rainbow trout sourced from both farm and aquarium settings.
Methods and ...Results
Samples of distal intestinal contents were collected from fish and subjected to high throughput 16S rRNA sequencing, to accurately determine the composition of the intestinal microbiome. The predominant phyla identified from both groups were Tenericutes, Firmicutes, Proteobacteria, Spirochaetae and Bacteroidetes. A novel metagenomic tool, PICRUSt, was used to determine the functional potential of the bacterial communities present in the rainbow trout intestine. Pathways concerning membrane transport activity were dominant in the intestinal microbiome of all fish samples. Furthermore, this analysis revealed that gene pathways relating to metabolism, and in particular amino acid and carbohydrate metabolism, were upregulated in the rainbow trout intestinal microbiome.
Conclusions
The results suggest that the structure of the intestinal microbiome in farmed rainbow trout may be similar regardless of where the fish are located and hence could be shaped by host factors. Differences were, however, noted in the microbial community membership within the intestine of both fish populations, suggesting that more sporadic taxa could be unique to each environment and may have the ability to colonize the rainbow trout gastrointestinal tract. Finally, the functional analysis provides evidence that the microbiome of rainbow trout contains genes that could contribute to the metabolism of dietary ingredients and therefore may actively influence the digestive process in these fish.
Significance and Impact of the Study
To better understand and exploit the intestinal microbiome and its impact on fish health, it is vital to determine its structure, diversity and potential functional capacity. This study improves our knowledge of these areas and suggests that the intestinal microbiome of rainbow trout may play an important role in the digestive physiology of these fish.
Salmonella Enteritidis (SE) has been the most common Salmonella serotype associated with foodborne infections in the last several years. Dietary applications of yeast-based preparations in feed have ...shown to reduce Salmonella colonization in chickens augmenting SE control strategies. This study was conducted to evaluate the effects of a mannan-rich yeast cell wall-derived preparation (Actigen®) administered in feed at a rate of 400 g/ton on SE colonization in the cecum and internal organs of commercial layer chickens. Sixteen week-old layer pullets were orally challenged with a selected nalidixic acid resistant SE strain at a dose of 1.7×10^9 colony forming units (CFU) per bird. SE colonization was assessed by evaluating isolation rates from ovary and pooled liver/spleen samples as well as enumeration of SE in cecal pouches one week post-challenge. Recovery rates of SE from the ovaries of directly challenged birds receiving Actigen® were significantly lower (P <0.02) than those in directly challenged birds fed an unsupplemented control diet. Recovery rates of SE from pooled liver/spleen samples were not significantly different between Actigen®-treated pullets and controls (P = 0.22). Using direct plate count methods, cecal SE concentrations were 1 log10 lower (P <0.001) in challenged pullets in the Actigen®-supplemented group than in the challenged controls. The SE concentration distributions in the ceca were similar in groups testing positive and groups testing negative for SE in the ovaries and liver/spleens tissues. As a result, SE concentrations in the ceca could not be directly related to the occurrence or prevalence of SE in these tissues. In conclusion, Actigen® supplementation appears to decrease the prevalence of SE in ovarian tissue and concentrations of SE in cecal contents and may be useful as a tool for reducing the risk of eggshell contamination and transovarian transmission of SE in eggs.
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