Transonic liquid bells

http://www.irphe.univ-mrs.fr/~clanet/PaperFile/PHFBell.pdfThe shape of a liquid bell resulting from the overflow of a viscous liquid out of a circular dish is investigated experimentally and theoretically. The main property of this bell is its ability to sustain the presence of a ‘‘transonic point,'' where the liquid velocity equals the speed of antisymmetric—or sinuous—surface waves. Their shape and properties are thus rather different from usual ‘‘hypersonic'' water bells. We first show that the bell shape can be calculated very accurately, starting from the sonic point.We then demonstrate the extreme sensitivity of the shape of these bells to the difference of pressure across the interface, making them a perfect barometer. Finally, we discuss the oscillations of the bell which occur close to the bursting limit

Monitoring of the biodegradation of toluene-contaminated sand in columns by SIP measurements, CO2 content and its 13C/12C isotopic signature.

Hydrocarbon contaminated soils represent an environmental issue as it impacts on ecosystems and aquifers. Bioremediation uses the ability of bacteria naturally present in the ground to degrade hydrocarbons. It represents an effective solution to fight the pollution but in situ monitoring before and during soil treatment is difficult and challenging. Indeed, where significant subsurface heterogeneity exists, conventional intrusive groundwater sampling can be insufficient to obtain a robust monitoring as the information they provide is restricted to vertical profiles at discrete locations, with no information between sampling points. In order to obtain wider information, complementary methods can be used like geo-electrical techniques. Induced polarization (IP) seems to be the more promising to study the effects of biodegradation processes. Indeed, laboratory and field experiments have shown an enhancement of real and imaginary parts of electrical conductivity while bacterial treatment is progressing (Abdel Aal et al., 2006 ; Atekwana et Atekwana, 2010). Moreover, microbial activity induced CO2 production and isotopic deviation of carbon (Aggarwal and Hinchee, 1991). The ratio δ13C(CO2) will come closer to δ13C(hydrocarbon). From these findings, the French project BIOPHY, supported by the French National Research Agency (ANR), proposes to use electrical methods and gas analyses to develop a non-destructive method for monitoring in situ biodegradation of hydrocarbons in order to optimize soil treatment. Laboratory experiments in columns are carried out to demonstrate its feasibility. Our objectives were to monitor aerobic microbial activity in toluene-contaminated sand columns using complex electrical resistivity measurements (SIP, Spectral Induced polarization and GEIS, Galvanostatic Electrochemical Impedance Spectroscopy) and measuring concentration and δ13C isotopic ratio of produced CO2

Mmp-9 and il-1\u3b2 as targets for diatoxanthin and related microalgal pigments: Potential chemopreventive and photoprotective agents

Photochemoprevention can be a valuable approach to counteract the damaging effects of environmental stressors (e.g., UV radiations) on the skin. Pigments are bioactive molecules, greatly attractive for biotechnological purposes, and with promising applications for human health. In this context, marine microalgae are a valuable alternative and eco-sustainable source of pigments that still need to be taken advantage of. In this study, a comparative in vitro photochemopreventive effects of twenty marine pigments on carcinogenic melanoma model cell B16F0 from UV-induced injury was setup. Pigment modulation of the intracellular reactive oxygen species (ROS) concentration and extracellular release of nitric oxide (NO) was investigated. At the cell signaling level, interleukin 1-\u3b2 (IL-1\u3b2) and matrix metallopeptidase 9 protein (MMP-9) protein expression was examined. These processes are known to be involved in the signaling pathway, from UV stress to cancer induction. Diatoxanthin resulted the best performing pigment in lowering MMP-9 levels and was able to strongly lower IL-1\u3b2. This study highlights the pronounced bioactivity of the exclusively aquatic carotenoid diatoxanthin, among the others. It is suggested increasing research efforts on this molecule, emphasizing that a deeper integration of plant ecophysiological studies into a biotechnological context could improve the exploration and exploitation of bioactive natural products

Triassic alkaline magmatism of the Hawasina Nappes: Post-breakup melting of the Oman lithospheric mantle modified by the Permian Neotethyan Plume

International audienceMiddle to Late Triassic lavas were sampled within three tectonostratigraphic groups of the Hawasina Nappes in the Oman Mountains. They are predominantly alkali basalts and trachybasalts, associated with minor sub-alkaline basalts, trachyandesites, trachytes and rhyolites. Their major, trace elements and Nd-Pb isotopic compositions are very similar to those of the Permian plume-related high-Ti basalts which also occur in the Hawasina Nappes. The Triassic lavas derive from low-degree melting of an enriched OIB-type mantle source, characterized by εNdi = 0.3-5.3 and (206Pb/204Pb)i = 16.96-19.31 (for t = 230 My). With time, melting depths decreased from the garnet + spinel to the spinel lherzolite facies and the degree of melting increased. The oldest are distinguished from the others by unradiogenic Nd and Pb signatures, with εNdi = − 4.5 to − 1.2 and (206Pb/204Pb)i = 16.35-17.08, which we attribute to their contamination by Arabo-Nubian lower crust. The lavas likely derived from the Oman lithospheric mantle, the original DMM-HIMU signature of which was overprinted during its pervasive metasomatism by the Permian plume-related melts. We suggest that these lavas were emplaced during post-breakup decompression-triggered melting in the Middle Triassic during global kinematic reorganization of the Tethyan realm

Antioxidant and Photoprotection Networking in the Coastal Diatom <i>Skeletonema marinoi</i>

Little is known on the antioxidant activity modulation in microalgae, even less in diatoms. Antioxidant molecule concentrations and their modulation in microalgae has received little attention and the interconnection between light, photosynthesis, photoprotection, and antioxidant network in microalgae is still unclear. To fill this gap, we selected light as external forcing to drive physiological regulation and acclimation in the costal diatom Skeletonema marinoi. We investigated the role of light regime on the concentration of ascorbic acid, phenolic compounds and among them flavonoids and their connection with photoprotective mechanisms. We compared three high light conditions, differing in either light intensity or wave distribution, with two low light conditions, differing in photoperiod, and a prolonged darkness. The change in light distribution, from sinusoidal to square wave distribution was also investigated. Results revealed a strong link between photoprotection, mainly relied on xanthophyll cycle operation, and the antioxidant molecules and activity modulation. This study paves the way for further investigation on the antioxidant capacity of diatoms, which resulted to be strongly forced by light conditions, also in the view of their potential utilization in nutraceuticals or new functional cosmetic products

Listeners Exploit Syntactic Structure On-Line to Restrict Their Lexical Search to a Subclass of Verbs

Many experiments have shown that listeners actively build expectations about up-coming words, rather than simply waiting for information to accumulate. The online construction of a syntactic structure is one of the cues that listeners may use to construct strong expectations about the possible words they will be exposed to. For example, speakers of verb-final languages use pre-verbal arguments to predict on-line the kind of arguments that are likely to occur next (e.g., Kamide, 2008, for a review). Although in SVO languages information about a verb's arguments typically follows the verb, some languages use pre-verbal object pronouns, potentially allowing listeners to build on-line expectations about the nature of the upcoming verb. For instance, if a pre-verbal direct object pronoun is heard, then the following verb has to be able to enter a transitive structure, thus excluding intransitive verbs. To test this, we used French, in which object pronouns have to appear pre-verbally, to investigate whether listeners use this cue to predict the occurrence of a transitive verb. In a word detection task, we measured the number of false alarms to sentences that contained a transitive verb whose first syllable was homophonous to the target monosyllabic verb (e.g., target “dort” /dɔʁ/ to sleep and false alarm verb “dorlote” /dɔʁlɔt/ to cuddle). The crucial comparison involved two sentence types, one without a pre-verbal object clitic, for which an intransitive verb was temporarily a plausible option (e.g., “Il dorlote” / He cuddles) and the other with a pre-verbal object clitic, that made the appearance of an intransitive verb impossible (“Il le dorlote” / He cuddles it). Results showed a lower rate of false alarms for sentences with a pre-verbal object pronoun (3%) compared to locally ambiguous sentences (about 20%). Participants rapidly incorporate information about a verb's argument structure to constrain lexical access to verbs that match the expected subcategorization frame

Degradation of hydrocarbons and heavy metal reduction by marine bacteria in highly contaminated sediments

Investigations on the ability of bacteria to enhance removal of hydrocarbons and reduce heavy metal toxicity in sediments are necessary to design more effective bioremediation strategies. In this study, five bacterial strains, Halomonas sp. SZN1, Alcanivorax sp. SZN2, Pseudoalteromonas sp. SZN3, Epibacterium sp. SZN4, and Virgibacillus sp. SZN7, were isolated from polluted sediments from an abandoned industrial site in the Gulf of Naples, Mediterranean Sea, and tested for their bioremediation efficiency on sediment samples collected from the same site. These bacteria were added as consortia or as individual cultures into polluted sediments to assess biodegradation efficiency of polycyclic aromatic hydrocarbons and heavy metal immobilisation capacity. Our results indicate that these bacteria were able to remove polycyclic aromatic hydrocarbons, with a removal rate up to ca. 80% for dibenzo-anthracene

Degradation of Hydrocarbons and Heavy Metal Reduction by Marine Bacteria in Highly Contaminated Sediments

Investigations on the ability of bacteria to enhance removal of hydrocarbons and reduce heavy metal toxicity in sediments are necessary to design more effective bioremediation strategies. In this study, five bacterial strains, Halomonas sp. SZN1, Alcanivorax sp. SZN2, Pseudoalteromonas sp. SZN3, Epibacterium sp. SZN4, and Virgibacillus sp. SZN7, were isolated from polluted sediments from an abandoned industrial site in the Gulf of Naples, Mediterranean Sea, and tested for their bioremediation efficiency on sediment samples collected from the same site. These bacteria were added as consortia or as individual cultures into polluted sediments to assess biodegradation efficiency of polycyclic aromatic hydrocarbons and heavy metal immobilisation capacity. Our results indicate that these bacteria were able to remove polycyclic aromatic hydrocarbons, with a removal rate up to ca. 80% for dibenzo-anthracene. In addition, these bacteria reduced arsenic, lead, and cadmium mobility by promoting their partitioning into less mobile and bioavailable fractions. Microbial consortia generally showed higher performance toward pollutants as compared with pure isolates, suggesting potential synergistic interactions able to enhance bioremediation capacity. Overall, our findings suggest that highly polluted sediments select for bacteria efficient at reducing the toxicity of hazardous compounds, paving the way for scaled-up bioremediation trials

The Microalgal Diatoxanthin Inflects the Cytokine Storm in SARS-CoV-2 Stimulated ACE2 Overexpressing Lung Cells

Contact between SARS-CoV-2 and human lung cells involves the viral spike protein and the human angiotensin-converting enzyme 2 (ACE2) receptor on epithelial cells, the latter being strongly involved in the regulation of inflammation as well as blood pressure homeostasis. SARS-CoV-2 infection is characterized by a strong inflammatory response defined as a "cytokine storm". Among recent therapeutic approaches against SARS-CoV-2 targeting the dramatic inflammatory reaction, some natural products are promising. Diatoms are microalgae able to produce bioactive secondary metabolites, such as the xanthophyll diatoxanthin (Dt). The aim of this study is to demonstrate the anti-inflammatory effects of Dt on the A549-hACE2 lung cell line, exploring its interaction with the ACE2 receptor, as well as depicting its role in inhibiting a cytokine storm induced by the SARS-CoV-2 spike glycoprotein. Results showed that Dt enhanced the cell metabolism, e.g., the percent of metabolically active cells, as well as the ACE2 enzymatic activity. Moreover, Dt strongly affected the response of the SARS-CoV-2 spike glycoprotein-exposed A549-hACE2 cells in decreasing the interleukin-6 production and increasing the interleukin-10 release. Moreover, Dt upregulated genes encoding for the interferon pathway related to antiviral defense and enhanced proteins belonging to the innate immunity response. The potential interest of Dt as a new therapeutic agent in the treatment and/or prevention of the severe inflammatory syndrome related to SARS-CoV-2 infection is postulated