Abstract: Contaminated groundwater is treated in-situ, by funnelling the water through a gate or gates (23) in a watertight in-ground wall (18). Treatment material in the gate (23) breaks down the contaminant, or otherwise removes the contaminant from the flowing water. A removable caisson is first driven into the ground, excavated, and then a receptacle, for the treatment material, is lowered into the hollow interior.

Abstract: A permeable wall (4) is located in the material of an aquifer (2), in the path of an approaching plume (3) of a contaminant (eg a chlorinated solvent). The wall comprises a body (7) of permeable filler material, eg sand and gravel, which is placed in a trench (5) that has been cut down into the aquifer material. Biologically-aided breakdown of the contaminant is aided by the presence of nutrients in the groundwater, and injection ports (18) are provided in the wall, through which the nutrients are injected periodically. The permeability of the wall helps the injected nutrients to spread laterally through the plume. The injected substances are contained in a volume of water; this water may be water which has been extracted from the trench, draw-off wells (9) being provided in the trench for that purpose. A second permeable wall (29) may be provided downstream for injection of eg air.

Abstract: The surface roughness of an extruded polymeric material is determined by forming a digital image of the extruded surface of the polymeric material and then determining the fractal dimension of any surface distortions of the extruded surface from the digital image. The fractal dimension is a measure of surface roughness and is dimensionless. A value of one indicates a smooth surface, while higher values indicated degrees of roughness. This information may be used to adjust molding conditions to avoid the formation of surface roughness.

Abstract: The joints between pile-driven sheet metal barrier elements (12, 14) have edge forms which interlock so as to form cavities (20, 21). The cavities extend from top to bottom of the barrier, and allow a flushing hose to be inserted to the foot of the barrier. Sealant is injected when the cavity is flushed clean. Two cavities are provided side by side at each joint. The cavities are independently sealed for extra reliability.

Abstract: Reforestation of cut forest regions is effected by broadcasting comminuted slash or cone-bearing roadside logging residue from delimbing of freshly-cut trees over the region from which the trees are cut. By comminuting the slash live seeds are released from cones contained in the slash and are returned to the forested area. In this way, an inexpensive reforestation procedure is provided and biodiversity is retained.

Abstract: A Sigma-Delta converter, has a receiver for receiving an input digital signal; a digital loop filter and quantizer having an input and an output; a summer having a first input connected to the receiver, a second input connected to the output of the digital loop filter and quantizer, and an output connected to the input of the digital loop filter and quantizer for subtracting from the input digital signal an output digital signal from the digital loop filter and quantizer, and in response generating a difference signal for application to the input of the digital loop filter and quantizer; and a digital-to-analog converter having a plurality of unit elements with minor mismatching therebetween, for receiving and converting to analog the output digital signal from the digital loop filter and quantizer, and in response generating an output analog signal, wherein the digital-to-analog converter has a selector for cyclically selecting successive different permutations of the unit elements for converting each value

Abstract: A system for treating groundwater contaminated with acidity or other contaminants is disclosed. The system involves excavating a trench into the aquifer in the path of the contaminant plume, and placing a body of active material in the trench. The active material depends on the particular contaminant: organic carbon may be used when the contaminant is ferrous sulphate, or hexavalent uranium oxide, or dissolved nitrate; pyrite or elemental iron may be used when the contaminant is e.g. chromium oxide. The active material causes the contaminant to transform or break down by chemical reaction into harmless precipitates and substances.

Abstract: Nitrate-polluted run-off water from a field is conveyed via land drains to a reservoir. The reservoir is large enough to contain excess quantities of storm water from the field. From the reservoir, the run-off water enters a tank which contains wood or other organic carbon material. The wood is kept under water, i.e. under anaerobic conditions, whereby the nitrate is broken down by bio-chemical action. Sufficient wood is provided, and the flow rate is so adjusted, that the nitrate-polluted water spends many hours in contact with the wood.

Abstract: Water draining from a septic tank contains ammonium, which traditionally is oxidized to nitrate in an aerobic soakaway. When the effluent enters the groundwater, the resulting nitrate concentration can be troublesome. A body of organic carbon, e.g. wood chppings, is provided, and the nitrate-laden effluent is passed through the carbon. The carbon is placed in the ground so as to be anaerobic: for example, the carbon may be placed below the water table; or the carbon may be mixed into a layer of fine silt, which is maintained in a state of tension-saturation by the effluent. Under anaerobic conditions, the nitrate is reduced by micro-biological action. The carbon is located such that the effluent naturally flows through the carbon, no pumps etc being required. The carbon may be located directly below the soakaway, or the carbon may be in a trench positioned to the side if the groundwater has a lateral component of flow.

Abstract: The down-hole sampler comprises a reservoir, with screw-down type valves top and bottom. The valves are arranged with the axes of the screw threads vertical. The valve members are integral with the structure of the sampler, whereby even with the valves screwed open, the sampler and the valves remain structurally intact. The sampler has a very slim overall diameter (down to 6 mm) and yet the valves are easy to operate, and sturdy and reliable in operation. The sampler includes a surface-operated check-valve for admitting a water sample into the reservoir.

Abstract: Biologically-active material, particularly hybridoma cells, is immobilized for mass culture in bioreactors to produce biological products, particularly monoclonal antibodies, by ionically-interacting polycationic groups on chitosan with polyanionic groups on a polyanionic water-soluble polymer. Preferably, the chitosan is chitosan acetate and the polyanionic polymer is sodium alginate. In one embodiment, droplets of a suspension of the biologically-active material and water-soluble polymer are gelled by forming a calcium salt of the water-soluble polymer to form temporary capsules, and a sequestering agent for the calcium ions is added to effect ionotropic gelation of the water-soluble polymer and chitosan to form a semi-permeable membrane around each temporary capsule. In another embodiment, porous beads are formed by exposing droplets of a suspension of the biologically active material and water-soluble polymer to an aqueous solution of chitosan and multiple cations.

Abstract: Senescence in perishable plant tissue is inhibited by the application thereto of an effective amount of a compound of the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each selected from the group consisting of hydrogen, --OH or --OR.sub.7, provided that at least one of R.sub.1 to R.sub.5 is a hydroxyl group, R.sub.6 is selected from the group consisting of --OH, --OR.sub.8 and --NHR.sub.9, R.sub.7 is a substituent group, R.sub.8 is the residue of an ester-forming compound and R.sub.9 is the residue of an amide-forming compound. The compound may be prepared synthetically and, in some cases, can be isolated from natural sources, for example, the glucose ester of ferulic acid may be isolated from carnation petals.

Abstract: Selective hydrogenation of the carbon-carbon double bonds of conjugated diene copolymers is effected in homogeneous solution in an organic solvent in the presence of certain divalent ruthenium carbonyl complex catalysts containing phosphine ligands having bulky alkyl substituents. The ruthenium catalysts have the general formula:RuXY(CO)ZL.sub.2 (1)orRuX(NO)(CO)L.sub.2 (2)wherein X is a halogen atom, most preferably chlorine, or a carboxylate group, Y is a halogen atom, more preferably chlorine, a hydrogen atom, a phenyl group, a carboxylate group or phenylvinyl group, Z is carbonyl, pyridine, benzontrile, trimethylphosphite or no ligand and L is a phosphine ligand having at least one bulky alkyl substituent, preferably tricyclohexyl or triisopropyl.

Abstract: Heavy crude oil emulsions are converted to lighter essentially sulphur-free and nitrogen-free hydrocarbons by Group VI B or Group VIII B metal compounds or complexes along with carbon monoxide, hydrogen or mixtures of carbon monoxide and hydrogen, and broken without the necessity for prior emulsion treatment and separation.

Abstract: The packing-seal is shown in use in a borehole as a level-isolating seal for a groundwater sampler. The packing-seal shown includes an expandable annulus of Dowell (TM) water-expandable material. Surrounding that is a pressure-sleeve of rubber. A sheet of woven Kevlar (TM) is wrapped circumferentially around the sleeve and the Dowell annulus, such that the ends of the Kevlar sheet overlap. Outside the Kevlar is an outer rubber sleeve. Upon expansion of the packing seal to fill the borehole, the Kevlar sheet unwraps to allow the Dowell to expand without restraint. Once the packing seal has filled the borehole, the Kevlar sheet is prevented from unwrapping further. If the borehole contains a fissure the Kevlar provides a rigid bridge over the fissure, and prevents the packing-seal from ballooning out into the fissure.

Abstract: The efficiency of trickle bed reactors is improved by periodically varying the liquid flow rate through the solids bed of the reactor. The reaction rate, conversion and product concentration can be increased using the novel operating procedure.

Abstract: The apparatus includes a sample-holder comprising a tube (16) of thin aluminum, and a piston (12) slidable in the tube. The piston is mounted on a solid, robust piston rod (14). To drive the apparatus down to the depth at which the sample is to be taken, the piston and tube are locked together, and travel down in unison, most of the force of the hammer blows being taken by the robust piston rod. When sampling depth is reached, the piston rod (14) is uncoupled, and the piston (12) is restrained by means of a cable (36) to the surface; further hammering now drives only the tube (16) downwards, not the piston. The tube being thin, the drive force is must less, whereby the tube does not collapse, as the sample enters the tube.

Abstract: An enhanced oil recovery process is described wherein oil is recovered from a depleted water-wet formation by the application of a gas to the formation. The flow of gas through the formation causes oil droplets to spontaneously form an oil film on connate water, which is extruded and discharged from the pores. The films pass through the formation under the influence of gravity, gradually accumulating more oil to form an oil mass which enters the producing well bore. A sem-permeable membrane may be used to prevent the inert gas from entering the well bore from the formation.

Abstract: Particulates in the form of fine dust are removed from gas streams by impinging the particles on screens located in the path of the particles to result in the build up of a deposit on the mesh, until the deposits grow to a sufficient size that the combined effect of gravity and gas flow dislodges the deposits, which are collected.

Abstract: Novel blended membranes are disclosed useful for the pervaporation separation of water-acetic acid mixtures and other miscible multicomponent systems. The blended membranes are formed from polyacrylic acid and nylon 6 or from polyvinyl alcohol, polyacrylic acid and nylon 4 or 6 by blending solutions of the materials, casting the blend and cross-linking the cast membrane.