A tale of three kingdoms: Members of the Phylum Nematoda independently acquired the detoxifying enzyme cyanase through horizontal gene transfer from plants and bacteria

Horizontal gene transfer (HGT) has played an important role in the evolution of nematodes. Among candidate genes, cyanase, which is typically found only in plants, bacteria and fungi, is present in more than 35 members of the Phylum Nematoda, but absent from free-living and clade V organisms. Phylogenetic analyses showed that the cyanases of clade I organisms Trichinella spp., Trichuris spp. and Soboliphyme baturini (Subclass: Dorylaimia) represent a well-supported monophyletic clade with plant cyanases. In contrast, all cyanases found within the Subclass Chromadoria which encompasses filarioids, ascaridoids and strongyloids are homologous to those of bacteria. Western blots exhibited typical multimeric forms of the native molecule in protein extracts of Trichinella spiralis muscle larvae, where immunohisto- chemical staining localized the protein to the worm hypodermis and underlying muscle. Recombinant Trichinella cyanase was bioactive where gene transcription profiles support functional activity in vivo. Results suggest that: (1) independent HGT in parasitic nematodes originated from different Kingdoms; (2) cyanase acquired an active role in the biology of extant Trichinella; (3) acquisition occurred more than 400 million years ago (MYA), prior to the divergence of the Trichinellida and Dioctophymatida, and (4) early, free-living ances- tors of the genus Trichinella had an association with terrestrial plants

Biolixiviation des métaux lourds et stabilisation des boues municipales: effet de la forme du souffre élémentaire utilisé comme substrat

La présence de concentrations élevées en métaux lourds retrouvés dans les boues de stations d'épuration est un facteur important limitant ainsi leurs différents modes de dispositions (rejet en mer, enfouissement, incinération, ou même recyclage comme fertilisant agricole ou forestier) par crainte de dégâts considérables qui pourraient être causés à l'environnement. L'objectif de ce travail consistait à mettre au point un procédé qui permettrait conjointement la stabilisation des boues municipales et l'enlèvement des métaux lourds qui y sont associés. L'approche poursuivie dans cette étude était de vérifier si ce procédé microbien, conçu pour enlever les métaux lourds associés aux boues municipales, pourrait éventuellement remplacer les procédés conventionnels de stabilisation des boues municipales, ce qui réduirait considérablement les temps et coûts de traitement. Ce procédé microbien consiste à utiliser des souches de thiobacilles qui oxydent le soufre élémentaire, produisant ainsi de l'acide sulfurique, et par la même occasion une forte baisse de pH (1.5). Les résultats obtenus en cultures discontinues, en bioréacteurs, avec des boues primaires provenant de la station d'épuration de la Communauté Urbaine de Québec (C.U.Q.- Est) montrent que cette chute de pH entraîne une solubilisation importante des métaux (Cr: 56 %, Cu: 97 %, Fe: 30 à 40 %, Pb: 69 %, Zn: 98 % ), du phosphore (52 %), ainsi qu'une réduction appréciable des matières volatiles en suspension (40 à 50 % ), et ce, après seulement 7 jours de traitement. Le soufre nécessaire à la biolixiviation- stabilisation est introduit, dans le cas de notre étude, sous forme de granules ou de blocs. Ce choix de la forme de soufre influe beaucoup sur la qualité de la boue produite, ainsi que sur son pouvoir acidophile après neutralisation. Le soufre en blocs s'avère plus efficace et aussi préférable au soufre en granules quant au pouvoir acidophile, après neutralisation, de la boue produite.Given the potential geochemical mobility and recognizd toxicity of heavy metals, their presence at high concentrations in sewage sludges imposes serious limitations on various sludge disposal practices (ocean disposal, landfill, incineration, or use as a fertilizer in agriculture or forestry), The objectve of this work was to develop a process that would permit the simultaneous stabilization of sewage sludges and the removal of heavy metals associated with them. The approach followed was to verify if this microbial leaching procedure could eventually replace conventional sludge stabilization processes and hence considerably reduce the time and cost of treatment. The microbial process consists of using thiobacillus strains which, in the presence of air, oxidize elemental sulfur to sulfuric acid, thus reducing the pH to very acidic levels (pH 1.5). This biological oxidation of elemental sulfur is brought about by two groups of sulfur-oxidizing bacteria, the less-acidophilic and the acidophilic thiobacilli. The initial acid production and pH reduction is due to the less-acidophilic bactena (Thiobacillus thioparus) which lower the pH to about 4.0. This is followed by the growth of acidophilic bacteria (Thiobacillus thiooxidans) and fruther pH reduction.Batch culture experiments were carried out in 30 L and 8 L reactors with primary sludges obtained from the Quebec urban community's wastewater treatment centre. Elemental sulfur and inoculum were added at the beginning of each experiment The inoculum was prepared by adding 1 % tyndalized sulfur powder to fresh secondary sludge and incubating for 8 days (final pH 1.5 to 2.0). A small portion (5 %) of this acidified sludge was then used as an inoculum for another batch of fresh sludge and this process was repeated several times until an acclimatized inoculum was obtained which could oxidize elemental sulfur rapidly, without an appreciable lag phase. The elemental sulfur necessary as substrate for the simultaneous bioleaching and sludge stabilization was introduced in the form of granules (2.4 to 4 mm diameter) or blocks (25 mm diameter).Sludge pH and ORP were measured at 24 hour intervals and all other measurements were carried out at 48 hour intervals. The results demonstrate that the addition of elemental sulfur and inoculum resulted in a considerable lowering of the sludge pH during the incubation period. Such pH lowering was not observed in cultures to which sulfur and inoculum were not added. This lowering of pH (2.1) was related to the quantity of substrate (sulfur) and inoculum present in the medium. An increase in the medium ORP (from -50 to about 500 mV) was also observed. Acidification of the medium along with the elevated ORP levels resulted in the solubilization of metals initially present in the sludge. This pH reduction, after only 7 days of treatment, effected an important metal solubilization (Cr: 56 %, Cu: 97 %, Be: 30-40 %, Pb: 69 %, Zn: 98 %), as well as an appreciable reduction in phosphorus (52 %) and in the volatile suspended solids concentration (40-50 %). In addition, the sludge which initially had a highly repulsive odour was rendered odourless.In a previous study we had showm that for an optimum rate of acidification of the sludge a minimum concentration of elemental sulfur (2 g/L) was necessary, even though only 40 % of this sulfur was oxidized. In the present experiment the physical form of the sulfur was shown to influence both the quality of sludge produced and its acid-generating capacity after neutralization. Sulfur in the form of blocks was more efficient than granules in that the elemental sulfur could be readily separated from the sludge at the end of the treatment, yielding a sludge after neutralization that had a low acid-generating capacity. In the case of granules, the unused sulfur was broken down into a fine powder during the course of the bioleaching experiment and could not be separated from the leached sludge - even after neutralization, the leached sludge exhibited a high acid-generating capacity, which would limit its use as a fertilizer on agricultural land

Revue sur l'enlèvement des métaux des effluents par adsorption sur la sciure et les écorces de bois

Les résidus de transformation du bois tels les écorces et la sciure de bois ont été largement étudiés depuis quelques années pour leur propriété d'adsorption et d'enlèvement des métaux toxiques contenus dans les effluents contaminés. En ce qui concerne la sciure de bois, les recherches répertoriées ont porté principalement sur l'utilisation du sapin rouge, du manga, du tilleul, de l'épinette, du pin, du cèdre, du teck, de l'akamatsu et du buna. Pour ce qui est des écorces de bois, plusieurs espèces ont été étudiées, notamment les écorces de pin, de chêne et d'épinette. La présente revue fait le point sur les performances de ces différents adsorbants peu coûteux pour l'adsorption des principaux métaux contaminants (Cd, Cr, Cu, Hg, Ni, Pb et Zn). Les points discutés portent sur les méthodes de préparation (lavage, séchage et tamisage) et de traitement chimique de l'adsorbant (traitement acide ou basique, traitement à la formaldéhyde, phosphatation, carboxylation, sulfoéthylation, carboxyméthylation, etc.), les conditions opératoires utilisées lors de l'adsorption, les modèles thermodynamiques, cinétiques et autres applicables au couple adsorbant-adsorbat, l'effet des principaux paramètres opératoires (temps de contact, pH de traitement, température, concentration d'adsorbant, taille des particules, etc.), les principes et les mécanismes impliqués dans l'élimination des contaminants métalliques par les adsorbants présentés.Wood industry by-products such as barks and sawdusts have been widely studied in recent years for their property of metal adsorption and metal removal from contaminated effluents. Concerning the utilization of sawdusts, many researchers have studied metal adsorption on material from species such as red fir, mango, lime, pine, cedar, teak, Japanese red pine and Japanese beech. As regards wood barks, several species were studied, in particular pine, oak and spruce. The present review gives a progress report on the efficiency of these various inexpensive materials for the adsorption of different metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn). The points discussed relate to the preparation methods (washing, drying, screening) and the chemical treatments of the adsorbents (acid or base treatment, formaldehyde treatment, phosphatation, carboxylation, sulfoethylation, carboxymethylation, etc.). We also consider the operating conditions used during adsorption, the thermodynamic, kinetic and other models applicable to the adsorbent-adsorbate couple, the effect of the operational parameters (time of contact, pH, temperature, adsorbent concentration, particle size, etc.), as well as the principles and mechanisms involved in metal removal by the adsorbents.The accumulation of organic or inorganic matter at the solid-liquid interface is the basis of almost all surface reactions. Adsorption is often a process described in terms of isotherms, which represent the relationship between the concentration of a solute in solution and the quantity adsorbed at the surface at constant temperature. The isotherms are often used to establish the maximum adsorption capacity of a given adsorbent for metals. Langmuir and Freundlich isotherms are the most frequently used and their models are presented in this review.Knowledge of adsorption parameters is essential for understanding the adsorption mechanisms involved. Usually, the maximum adsorption capacity for sawdusts and barks is reached after one hour. The pH of the ambient water is a very important parameter because it affects the metal adsorption capacities. For most of the metals studied, the adsorption capacity increases when the pH increases. The opposite effect is observed for metals involved in an anionic complex (Cr, Se, Pt, Au). Metal adsorption efficiency also improves with increases in substrate concentration because there are more available adsorption sites. Metal adsorption is affected by an another important factor, the particle size. In effect, a smaller size particle increases the specific surface and improves the adsorption capacity. The presence of anions in the effluent doesn't appear to have a great effect on adsorption results with sawdusts. However, some anions were reported to have an influence on the metal adsorption capacities of barks. In the case of a metal mixture, the presence of one metal may influence, compete or exclude the recovery of another metal from the solution.Sawdusts contain lignin, cellulose, tannin and protein. Wood tannin likely serves as a primary adsorption site for divalent cations. The application of chemical treatments on sawdusts could modify the lignin functional groups. Other studies regarding the participation of major components of barks (lignin, carbohydrate and protein) in the adsorption process revealed the involvement of amine and carboxyl functional groups. The proposed mechanism involves an ion-exchange process. This phenomenon suggests that cationic exchange is the active mechanism for some wood species, in agreement with the work of some researchers.Currently, only a few industries use plant biomass to eliminate metals in wastewater. To encourage industries to use this biotechnology, research has to be oriented towards the cheapest and most competitive process rather than the current and conventional process. Forest waste products are produced in large quantities in several countries. They constitute easily-available resources of low cost. Future research in this field should be focused on cheap new chemical treatments to apply to by-products to improve their adsorption capacities

High-pressure structural investigation of several zircon-type orthovanadates

Room temperature angle-dispersive x-ray diffraction measurements on zircon-type EuVO4, LuVO4, and ScVO4 were performed up to 27 GPa. In the three compounds we found evidence of a pressure-induced structural phase transformation from zircon to a scheelite-type structure. The onset of the transition is near 8 GPa, but the transition is sluggish and the low- and high-pressure phases coexist in a pressure range of about 10 GPa. In EuVO4 and LuVO4 a second transition to a M-fergusonite-type phase was found near 21 GPa. The equations of state for the zircon and scheelite phases are also determined. Among the three studied compounds, we found that ScVO4 is less compressible than EuVO4 and LuVO4, being the most incompressible orthovanadate studied to date. The sequence of structural transitions and compressibilities are discussed in comparison with other zircon-type oxides.Comment: 34 pages, 2 Tables, 11 Figure

Rotational Dynamics of Organic Cations in CH3NH3PbI3 Perovskite

Methylammonium lead iodide (CH3NH3PbI3) based solar cells have shown impressive power conversion efficiencies of above 20%. However, the microscopic mechanism of the high photovoltaic performance is yet to be fully understood. Particularly, the dynamics of CH3NH3+ cations and their impact on relevant processes such as charge recombination and exciton dissociation are still poorly understood. Here, using elastic and quasi-elastic neutron scattering techniques and group theoretical analysis, we studied rotational modes of the CH3NH3+ cation in CH3NH3PbI3. Our results show that, in the cubic (T > 327K) and tetragonal (165K < T < 327K) phases, the CH3NH3+ ions exhibit four-fold rotational symmetry of the C-N axis (C4) along with three-fold rotation around the C-N axis (C3), while in orthorhombic phase (T < 165K) only C3 rotation is present. Around room temperature, the characteristic relaxation times for the C4 rotation is found to be ps while for the C3 rotation ps. The -dependent rotational relaxation times were fitted with Arrhenius equations to obtain activation energies. Our data show a close correlation between the C4 rotational mode and the temperature dependent dielectric permittivity. Our findings on the rotational dynamics of CH3NH3+ and the associated dipole have important implications on understanding the low exciton binding energy and slow charge recombination rate in CH3NH3PbI3 which are directly relevant for the high solar cell performance

Practical long-distance quantum key distribution system using decoy levels

Quantum key distribution (QKD) has the potential for widespread real-world applications. To date no secure long-distance experiment has demonstrated the truly practical operation needed to move QKD from the laboratory to the real world due largely to limitations in synchronization and poor detector performance. Here we report results obtained using a fully automated, robust QKD system based on the Bennett Brassard 1984 protocol (BB84) with low-noise superconducting nanowire single-photon detectors (SNSPDs) and decoy levels. Secret key is produced with unconditional security over a record 144.3 km of optical fibre, an increase of more than a factor of five compared to the previous record for unconditionally secure key generation in a practical QKD system.Comment: 9 page

Characterization of Extracellular Polymeric Substances (Eps) Produced by \u3ci\u3eCloacibacterium normanense\u3c/i\u3e Isolated from Wastewater Sludge for Sludge Settling and Dewatering

In this study, extracellular polymeric substances (EPSs) producing strain was isolated from municipal wastewater sludge (MWWS). Growth profile and the EPS production by Cloacibacterium normanense using wastewater sludge as raw material in shake flask fermentation for 96 h were investigated. The highest concentration of S-EPS (13.0 ± 0.8 g/L) and C-EPS (0.3 ± 0.1 g/L) were attained at 48 h of fermentation. S-EPS revealed higher flocculation activity (94.2%) and dewaterability (59.9%) than other types of EPS in kaolin suspension. The dewaterability of MWWS with 2 g suspended solids (SS)/L was improved by 37.6% using 0.02 ± 0.01 g/L of S-EPS and 600 mg/L of Al2(SO4)3. The study showed a promising approach of new isolated strain to produce high concentration EPS in sludge with high flocculation activity as well as good settlin

Characterization of Extracellular Polymeric Substances (Eps) Produced by \u3ci\u3eCloacibacterium normanense\u3c/i\u3e Isolated from Wastewater Sludge for Sludge Settling and Dewatering

In this study, extracellular polymeric substances (EPSs) producing strain was isolated from municipal wastewater sludge (MWWS). Growth profile and the EPS production by Cloacibacterium normanense using wastewater sludge as raw material in shake flask fermentation for 96 h were investigated. The highest concentration of S-EPS (13.0 ± 0.8 g/L) and C-EPS (0.3 ± 0.1 g/L) were attained at 48 h of fermentation. S-EPS revealed higher flocculation activity (94.2%) and dewaterability (59.9%) than other types of EPS in kaolin suspension. The dewaterability of MWWS with 2 g suspended solids (SS)/L was improved by 37.6% using 0.02 ± 0.01 g/L of S-EPS and 600 mg/L of Al2(SO4)3. The study showed a promising approach of new isolated strain to produce high concentration EPS in sludge with high flocculation activity as well as good settlin

New high-pressure phase and equation of state of Ce2Zr2O8

In this paper we report a new high-pressure rhombohedral phase of Ce2Zr2O8 observed from high-pressure angle-dispersive x-ray diffraction and Raman spectroscopy studies up to nearly 12 GPa. The ambient-pressure cubic phase of Ce2Zr2O8 transforms to a rhombohedral structure beyond 5 GPa with a feeble distortion in the lattice. Pressure evolution of unit-cell volume showed a change in compressibility above 5 GPa. The unit-cell parameters of the high-pressure rhombohedral phase at 12.1 GPa are ah = 14.6791(3) {\AA}, ch = 17.9421(5) {\AA}, V = 3348.1(1) {\AA}3. The structure relation between the parent cubic (P2_13) and rhombohedral (P3_2) phases were obtained by group-subgroup relations. All the Raman modes of the cubic phase showed linear evolution with pressure with the hardest one at 197 cm-1. Some Raman modes of the high-pressure phase have a non-linear evolution with pressure and softening of one low-frequency mode with pressure is found. The compressibility, equation of state, and pressure coefficients of Raman modes of Ce2Zr2O8 are also reported.Comment: 33 pages, 8 figures, 6 table

Phonons and Colossal Thermal Expansion Behavior of Ag3Co(CN)6 and Ag3Fe(CN)6

Recently colossal positive volume thermal expansion has been found in the framework compounds Ag3Co(CN)6 and Ag3Fe(CN)6. Phonon spectra have been measured using the inelastic neutron scattering technique as a function of temperature and pressure. The data has been analyzed using ab-initio calculations. We find that the bonding is very similar in both compounds. At ambient pressure modes in the intermediate frequency part of the vibrational spectra in the Co compound are shifted to slightly higher energies as compared to the Fe compound. The temperature dependence of the phonon spectra gives evidence for large explicit anharmonic contribution to the total anharmonicity for low-energy modes below 5 meV. We found that modes are mainly affected by the change in the size of unit cell, which in turn changes the bond lengths and vibrational frequencies. Thermal expansion has been calculated via the volume dependence of phonon spectra. Our analysis indicates that Ag phonon modes in the energy range from 2 to 5 meV are strongly anharmonic and major contributors to thermal expansion in both compounds. The application of pressure hardens the low-energy part of the phonon spectra involving Ag vibrations and confirms the highly anharmonic nature of these modes.Comment: 19 pages, 14 figures and one tabl