A theoretical/experimental program to develop active optical pollution sensors

Light detection and ranging (LIDAR) technology was applied to the assessment of air quality, and its usefulness was evaluated by actual field tests. Necessary hardware was successfully constructed and operated in the field. Measurements of necessary physical parameters, such as SO2 absorption coefficients were successfully completed and theoretical predictions of differential absorption performance were reported. Plume modeling improvements were proposed. A full scale field test of equipment, data analysis and auxiliary data support was conducted in Maryland during September 1976

Le traitement des eaux usées

L'article présente brièvement l'état de l'épuration des effluents des collectivités en France et au Québec. Il souligne ensuite quelques changements importants intervenus depuis dix ans dans le monde grâce aux progrès de la recherche et qui pourraient marquer l'avenir.En France, 95 % des agglomérations de plus de 10 000 équivalents-habitants disposent d'une station d'épuration. Le rythme de construction a atteint 730 installations nouvelles dans l'année 1976 mais il est redescendu à moins de 300/an. Sur les 11 310 stations de plus de 200 équivalents-habitants recensées, 5 % réalisent seulement un traitement primaire et la moitié en nombre, représentant plus de 60 % de la capacité de traitement utilisent le procédé des boues activées.Les investissements à réaliser entre 1994 et 2005 pour satisfaire aux exigences de la directive européenne du 21 mai 1991 sont évalués à environ 36 milliards de francs français, correspondant à la création de capacités de traitement supplémentaires de 17 millions d'équivalents-habitants et à des améliorations plus ou moins importantes d'un grand nombre de stations existantes.Au Québec, la construction des stations d'épuration s'est faite essentiellement dans les années 80 et 90. Aujourd'hui, près de 80 % de la population est desservie par des installations d'épuration, soit environ 4,9 millions d'habitants pour un débit hydraulique de 5,3 millions de m3/j.Parmi les 450 ouvrages municipaux ceux des Communautés Urbaines de Montréal et de Québec représentent, à eux seuls, près de 60 % de la capacité installée.Les stations physico-chimiques, bien que peu nombreuses, sont les plus importantes (6 stations pour 2,28 millions d'habitants) suivies par les boues activées (40 stations pour 0,69 million d'habitants) et la biofiltration (9 stations pour 0,75 million d'habitants). Environ 320 stations, de dimension plus modeste utilisent des étangs aérés, desservant en moyenne une population de 3 500 habitants.Sur le plan de l'évolution des techniques, la décennie écoulée a vu apparaître ou se confirmer des évolutions qui marqueront sans doute profondément la conception et l'exploitation des stations d'épuration dans les années à venir : - l'objectif maintenant presque généralisé d'éliminer les nutriments azote et phosphore et le développement rapide des techniques correspondantes;- la prise de conscience de l'importance des flux polluants véhiculés par les eaux pluviales et un début d'adaptation des stations d'épuration;- le développement limité mais réel des traitements anaérobies qui ont survécu à la démobilisation des surlendemains de la crise énergétique;- le fort développement des systèmes d'épuration biologique à culture fixée et notamment des biofiltres;- l'apparition prometteuse des membranes dans les systèmes d'épuration biologique permettant d'envisager de nouveaux objectifs de traitement;- la prise en compte de la fiabilité des systèmes d'épuration avec un poids de plus en plus important par rapport aux performances de pointe- une vision plus intégrée de la prévention des pollutions tant dans l'industrie (technologies propres) que dans les agglomérations (gestion intégrée de l'ensemble réseau-station d'épuration).This paper provides a brief discussion of the state of municipal wastewater treatment in France and Quebec. It then presents some important changes that have developed over the last ten years in the world and their potential influence on the future.In France, 95% of towns of more than 10 000 residents have a wastewater treatment plant. Construction of new plants reached 730 installations in 1976, but has since declined to less than 300/year. Among 11 310 sites of more of 200 inhabitants, 5 % utilize only primary treatment and 50 % utilize the activated sludge process which represents 60 % of the treatment capacity.In order to satisfy the European directive of May 21st 1991, approximately 36 billion French Francs should be invested between 1994 and 2005. This investment represents new wastewater treatment facilities for 17 million people.In Quebec, construction of wastewater treatment plants occurred mainly during the 80's and 90's. Today, nearly 80 % of the population is served by wastewater treatment plants, which represent approximately 4,9 million residents. This accounts for a flow rate of 5,3 million cubic meters per day.Among 450 municipal treatment plants, those of the urban communities of Montreal and Quebec represent nearly 60 % of the total wastewater treatment capacity of Quebec.Physico-chemical treatment plants are the most significant (6 plants for 2,28 million residents) followed by activated sludge process plants (40 plants for 0,69 million residents) and plants using biofilter technologies (9 plants for 0,75 million residents). A total of approximately 320 small treatment plants, serving an average of 3 500 residents, use the aerated lagoon treatment.Over the past decade technological developments have resulted in an evolution that will modify the design and operation of wastewater treatment plants in the future:- the more widespread use of techniques developed for the elimination of nitrogen and phosphorus; - the realization of the importance of polluting charges transported by pluvial waters; the beginning of the resultant wastewater treatment plant adaptations; - the limited development of anaerobic treatments that have survived the energy crisis; - the valuable development of biological fixed-culture systems for wastewater treatment and most notably, the biofilters; - the appearance of promising membrane technology in wastewater treatment systems, which could facilitate the definition of new treatment objectives; - the consideration the global reliability of the wastewater treatment systems instead of only peak performance; - a more integrated vision for the prevention of pollution in industry (clean technologies) as well as in the domestic environment (integrated management of sewerage system and wastewater treatment plant

Epigenetic regulation of satellite cell activation during muscle regeneration

Satellite cells are a population of adult muscle stem cells that play a key role in mediating muscle regeneration. Activation of these quiescent stem cells in response to muscle injury involves modulating expression of multiple developmentally regulated genes, including mediators of the muscle-specific transcription program: Pax7, Myf5, MyoD and myogenin. Here we present evidence suggesting an essential role for the antagonistic Polycomb group and Trithorax group proteins in the epigenetic marking of muscle-specific genes to ensure proper temporal and spatial expression during muscle regeneration. The importance of Polycomb group and Trithorax group proteins in establishing chromatin structure at muscle-specific genes suggests that therapeutic modulation of their activity in satellite cells could represent a viable approach for repairing damaged muscle in muscular dystrophy

Quantum Heating of a nonlinear resonator probed by a superconducting qubit

We measure the quantum fluctuations of a pumped nonlinear resonator, using a superconducting artificial atom as an in-situ probe. The qubit excitation spectrum gives access to the frequency and temperature of the intracavity field fluctuations. These are found to be in agreement with theoretical predictions; in particular we experimentally observe the phenomenon of quantum heating

Manufacturing checkout of orbital operational stages Midterm report, period ending 24 Feb. 1965

Manufacturing checkout of orbital operational Saturn S-IVB stage and instrument unit for parking orbit operation

État du développement technologique en matière d'enlèvement des métaux des effluents industriels

Cette étude trace un profil des diverses technologies utilisées et en développement pour la séparation et/ou la récupération des métaux dans les effluents industriels. Les principes de fonctionnement de ces technologies sont abordés, ainsi que leurs avantages et limites d'utilisation. Les procédés d'enlèvement et de récupération des métaux comprennent les techniques de précipitation (formation d'hydroxydes, de carbonates, de sulfures, etc.) et coprécipitation (sels de fer et d'aluminium, etc.), d'adsorption (sable, cellulose, charbon activé, pyrite, ciment, lignite, mousse de tourbe, sciure de bois, etc.) et de biosorption (bactéries, levures, moisissures, algues marines et d'eaux douces), d'électrodéposition et d'électrocoagulation, de cémentation, de séparation par membranes (osmose inverse et électrodialyse), d'extraction par solvant (acides carboxyliques, amines aliphatiques ou aromatiques, acides aminés, composés phénoliques, phosphates alkyl, etc.), et d'échange d'ions (résines naturelles et synthétiques). La précipitation ou la coprécipitation représentent les procédés les plus largement utilisés et étudiés pour l'enlèvement des métaux des effluents industriels, suivis des techniques d'adsorption. Les procédés plus sophistiqués tels que l'électrodéposition, l'extraction par solvant, la séparation par membranes et l'échange d'ions, bien que largement utilisés dans les procédés métallurgiques, sont relativement peu employés et examinés pour le traitement des effluents industriels. La biosorption a fait l'objet de plusieurs travaux de recherche au cours des dernières années et représente une option intéressante pour le traitement de divers types d'effluents contenant de faibles concentrations en métaux. Finalement, le recyclage et la gestion optimale des effluents constitue une avenue de plus en plus suivie par les industries soucieuses de satisfaire aux nouvelles réglementations et législations.This study is dedicated to the review of the different technologies used and evaluated for the removal and/or recovery of metals from industrial effluents. The principles involved in these technologies are discussed, as well as the advantages and limits associated with these processes. The metal removal and recovery processes include the following techniques: precipitation, adsorption and biosorption, electrowinning and electrocoagulation, cementation, membrane separations, solvent extraction and ion exchange.Precipitation and coprecipitation are the most used and studied methods for metal removal from industrial waste waters. The method of precipitation used most often to remove metals from waste water consists of precipitating them in the form of hydroxides. The usual procedure involves the addition of chemicals such as lime (CaO or Ca(OH)2), Mg(OH)2, NaHCO3, Na2 CO3, (NH4)2 CO3, NaOH or NH4 OH. The precipitation of metals by carbonates or sulphides is an effective alternative to hydroxide precipitation. The use of carbonates allows the precipitation of metals to occur at pH values lower than those necessary with the hydroxides. Moreover, the precipitates thus formed are denser and have better characteristics of solid-liquid separation. Precipitation by sulphides is normally carried out with reagents such as: Na2 S, NaHS, H2 S or FeS. In acidic media, the lower solubility of metal sulphides (Cd, Co, Cu, Cr, Ni, Mn, Zn, etc.), makes it possible to reach concentrations lower than those obtained by precipitation as hydroxides. Coprecipitation with aluminum and iron salts is also an effective means for the removal of metals from effluents.Adsorption methods are also widely applied and examined for this purpose. However, in most cases the use of adsorbents requires an effluent neutralization step. Indeed, the neutralization of acid effluents must take place to allow their disposal in sewerage systems. A wide variety of adsorbents can be employed, both organic and inorganic: aluminum or iron oxides, sand, activated carbon, mixtures of coal and pyrite, iron particles, gravel or crushed brick, cement, etc. Studies have demonstrated the possibility of eliminating metals by adsorption on vegetable matter: peat moss, sawdust and wood bark, etc. Chitin and chitosan, two natural polymers that are abundant in the cell walls of fungi and shellfish, also have excellent properties of metal fixation. The utilization of different agricultural by-products (peanut skins, coconuts, corn cobs, onions skins, tea leaves, coffee powder, canola meal, etc.) for metal adsorption has also been proposed.Biosorption has been intensively studied in recent years as an economical treatment for metal recovery from dilute industrial effluents. Biosorption implies the use of live or dead biomass and/or their derivatives, which adsorb the metal ions with the ligands or functional groups located on the external surface of the microbial cells. Capacities for metal adsorption on various types of biomass (bacteria, yeasts, fungi, marine and freshwater algae) have been evaluated. The microorganisms used for the metal adsorption step must usually be immobilized in a matrix or in an easily recoverable support. The immobilizing agents or matrices most usually employed are alginate, polyacrylamine, polysulphone, silica gel, cellulose and glutaraldehyde.Electrowinning is a well-established technology that is widely employed in the mining and metallurgical industries (heap leaching, acid mine drainage, etc.), in metal transformation industries (wastes from plating and metal finishing), and in the electronics and electrical industries for the removal and/or the recovery of metals in solution. Many metals (Ag, Au, Cd, Co, Cr, Cu, Ni, Pb, Sn and Zn) present in the effluents can be recovered by electrodeposition using insoluble anodes.Electrocoagulation is another electrochemical approach, which uses an electrical current to remove several metals in solution. In fact, the electrocoagulation systems can be effective in removing suspended solids, dissolved metals, tannins and dyes. The contaminants present in waste water are maintained in solution by electrical charges. When these ions and the other charged particles are neutralized with ions of opposite electric charge, provided by a electrocoagulation system, they become destabilized and precipitate in a form that is usually very stable.Cementation is a type of precipitation method implying an electrochemical mechanism. In this process, a metal having a higher oxidation potential passes into solution (e.g., oxidation of metallic iron, Fe(0), to ferrous iron, Fe(II)) to replace a metal having a lower oxidation potential. Copper is the metal most frequently separated by cementation. However, the noble metals (Ag, Au and Pd), as well as As, Cd, Ga, Pb, Sb and Sn, can also be recovered in this manner.Reverse osmosis and electrodialysis are two processes using semipermeable membranes applicable to the recovery of metal ions. In electrodialysis, selective membranes (alternation of cation and anion membranes) fit between the electrodes in electrolytic cells. A continuous electrical current and the associated ion migrations, allow the recovery of metals. The techniques of membrane separation are very efficient for the treatment of dilute waste waters.The metallurgical industry has used solvent extraction for many years for a broad range of separations. This technique is employed today for the removal of soluble metals (Cd, Cr, Co, Cu, Ni, Mo, U, V, Zn, etc.) from waste water. Separation is carried out in contact with an immiscible organic phase to form salts or complex compounds, which give a favorable solubility distribution between the aqueous and organic phases. Various types of reagents can be used for the extraction: carboxylic acids, aliphatic or aromatic amines, amino acids, alkyl phosphates, phenolic compounds. The non-selective removal of metal contaminants in aqueous solutions can be obtained with a whole range of organic reagents. Promising new reagents have been proposed recently for the selective extraction of metals, such as Cd, Co, Cr and Zn.Ion exchangers are insoluble substances having in their molecular structure acidic or basic groups able to exchange, without modification of their physical structure, the positive or negative ions fixed at these groups. The first ion exchangers used were natural substances containing aluminosilicates (zeolites, clays, etc). Nowadays, the most-used ion exchangers are mainly organic in nature (resins). For the extraction of metals, the removal of cations in solution is usually done with the sulphonic acid group (-SO3- H+) of a polystyrene resin, or, with a chelating resin containing iminodiacetate functional groups. Ion exchange has recently received considerable attention for the separation and concentration of metals from waste water. These developments are especially applicable to the plating and metal transformation industries, for the removal of Cr, Co, Cu, Cd, Ni, Fe and Zn.The more sophisticated processes, such as electrowinning, solvent extraction, membrane separations and ion exchange, although frequently used in metallurgical processes, are less popular for wastewater treatment than are precipitation methods. Finally, recycling and optimal management of effluents constitutes an approach more and more widely applied by industries to satisfy new environmental regulations and laws