Preparation of vanadyl porphyrin complexes from a metal-porphyrin petroleum concentrate and study of their catalytic activity

A mixture of vanadyl porphyrin complexes was obtained from a metal-porphyrin concentrate (MPC) isolated from crude petroleum by selective extraction. The petroleum MPC was subjected to demetallization and the subsequent introduction of the vanadyl cation into the porphyrin ring. It was shown that the mixture of vanadyl-porphyrin complexes obtained from MPC catalyzes the cyclohexene epoxidation reaction. On the basis of experimental data, it was assumed that the mechanism of olefin oxygenation in the presence of vanadyl porphyrin complexes is similar to the mechanism of the Prilezhaev epoxidation reaction of unsaturated compounds.     

Application of a multi-channel system for continuous monitoring and an early warning system.

A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system.     

Nanolayered lightweight flexible shields with multidirectional optical transparency

New nanolayered coatings are designed and deposited on flexible plastic substrate having the thickness of 100 /spl mu/m, in order to realize lightweight ultrathin transparent shielding foils. The structure of the coating is optimized considering three figures of merit: the average transmittance in the visible range for normal incidence, the normalized average transmittance for oblique incidence at 550 nm, and the transmittance quality factor. The nanotechnology exploited for the deposition of the transparent metals is the dual ion beam sputtering. Tests of durability, optical transmission, and shielding effectiveness demonstrate that the film has a high adhesion under mechanical solicitation, high resistance against aging, peak transmittance in the visible range higher than 70%, omnidirectional properties in the range 0/spl deg/-60/spl deg/, and shielding effectiveness of 40 dB up to 6 GHz.     

Comfort limits for asymmetric thermal radiation

Groups of 32 and 16 subjects of both sexes were exposed in an environmental chamber to radiant asymmetry caused by a cool wall, a warm wall, and a cool ceiling. Each subject was tested individually while seated and clothed at 0.6 clo. During each 3.5-hour experiment the subject was exposed to six radiant temperature asymmetries. He was asked whether and where he experienced any local cool or warm sensation, and whether it was felt to be uncomfortable. During the entire experiment he was kept thermally neutral by changing the air temperature according to his wishes.For cool walls, warm walls, and cool ceilings curves have been established showing the percentage of dissatisfied subjects as a function of the radiant asymmetry. Radiant asymmetry at a warm wall caused less discomfort than a cool wall. A cool ceiling caused less discomfort than a warm ceiling. Accepting that 5% of the subjects may feel uncomfortable. a radiant temperature asymmetry of 10°C is allowable at a cool wall, 23°C at a warm wall, and 14°C under a cool ceiling. A previous study showed that 4°C is allowable under a warm ceiling. Radiant asymmetry had no significant impact on the operative temperatures preferred by the subjects. No significant differences were observed between the responses of men and women exposed to radiant asymmetry.     

Determination of precompression and compression force levels to minimize tablet friability using simplex

Pilot simplex experiments for improving the tablet strength of three aspirin tablet formulations based on precompression and compression forces were presented. As each simplex moved towards the direction of the optimum, the friability was being minimized and the crushing strength was concomittantly being maximized. Because it followed a systematic direction, simplex process would locate a local optimum rapidly. The appropriate levels of precompression and compression forces that produced tablets with the desired strength were attained in five trials. By contrast, random search for this force combination required at least ten trials. Simplex technique is a cost and time effective means for determining the precompression and compression forces that will reduce the friability or increase the hardness of a tablet formulation. Results appeared to also indicate that crushing strength might be a more reliable measure of tablet strength than friability.     

Experimental abatement data of underflow baffles for removal of floatables in the CSOs of the Greater Montréal (Canada) area.

Underflow baffles have gained in popularity over the years as a viable mean to intercept floatables in Combined Sewer Overflows (CSOs). This choice was mainly justified by the extremely low capital cost (CAPEX) and operational cost (OPEX) of this solution, although the efficiency of underflow baffles has never been clearly proven. The only similar application to underflow baffles are scum boards in grit chambers and clarifier. However, the flow conditions at CSOs vary considerably from those in grit chambers and clarifier. For this reason, review of the behavior of floatables in a rapid flow is paramount. Only then can comprehensive design criteria for underflow baffles and overflow chambers be suggested. Pilot scale tests, performed in a 17 metres long basin at various flowrates, had already shown that a critical horizontal velocity for floatables (Vcr) may develop in the overflow chambers. In this follow up study, the fate of intercepted floatables was investigated. It appears from this latest data that permanent capture of floatables decreases rapidly with an increase in the horizontal velocity of the flow, no matter what the baffle depth. Baffle depth increases capture at lower velocities (0.17 m/s) but become irrelevant at higher velocities (0.61 m/s). This data suggests that capture efficiency of existing underflow baffles in overflow chambers can be, at best, very low whenever the horizontal velocity increases above 0.30 m/s or 1 ft/s.     

Finite element analysis of helicoidal waveguides

The purpose of the paper is to propose an efficient method to compute propagation modes in helicoidal waveguides. An helicoidal system of co-ordinates is introduced to define the structure and to set up the problem. These co-ordinates, albeit non-orthogonal, preserve the translational invariance in a way that allows a two-dimensional finite element model similar to that of classical straight waveguides     

Effects of flux enhancing polymer on the characteristics of sludge in membrane bioreactor process.

A newly developed membrane performance enhancer (MPE) was used to prevent membrane fouling in a membrane bioreactor (MBR) process. It transpired that 1,000 mg/l of MPE reduced polysaccharide levels from 41 mg/I to 21 mg/I on average under the experimental condition. Repeated experiments also confirmed that 50-1,000 mg/l of MPE could reduce membrane fouling significantly and increase the intervals between membrane cleanings. Depending on MPE dosages and experimental conditions, trans-membrane pressure (TMP) increase was suppressed for 20-30 days, while baseline TMP surged within a few days. In addition, MPE allowed MBR operation even at 50,000 mg/l of total solid and reduced permeate COD. However, no evidence of toxicity for sludge was found from respiratory works.     

High performance biofilm process for treating wastewater discharged from coal refining plants containing nitrogen, cyanide and thiocyanate.

Wastewater discharge from coal refining plants contains a number of biologically toxic compounds; 2000-2500 mg/l of COD of which 40% is composed of phenol, 100-400 mg/l of thiocyanate, 10-40 mg/l of cyanide, 100-250 mg/l of NH4+-N and 150-300 mg/l of total nitrogen. In order to treat this kind of high strength wastewater, we have developed a high performance biofilm process using fluidizing bio-carriers of the tube chip type. The fluidizing biofilm carriers are made of a composite of polyethylene and several inorganic materials, whose density is controlled at 0.97-0.98 g/ml. The fluidizing biofilm carriers show sound fluidization characteristics inside bioreactors. The wastewater is treated using three consecutive series reactors in oxic-anoxic-oxic arrangement. Each reactor is charged with the fluidizing biofilm carriers of 50 vol%. Furthermore, newly cultured active microorganisms for the thiocyanate biodegradation are added in the biofilm process. At total hydraulic retention time of 2.2 days, this process can achieve steady state removal efficiencies: COD, 99%; thiocyanate, 99%; NH4+-N, 99% and total nitrogen, 90%.     

The impact of new product development acceleration approaches on speed and profitability: lessons for pioneers and fast followers

This work investigates the impact of nine new product development (NPD) acceleration approaches (supplier involvement, lead user involvement, speeding up activities and tasks, reduction of parts and components, training and rewarding of employees, implementation of support systems and techniques, stimulating interfunctional cooperation, emphasis on the customer, and simplification of organizational structure) on development speed and new product profitability. Our findings from 233 manufacturing firms show that lead user involvement and training/rewarding of employees increase both development speed and profitability. Supplier involvement, speeding up activities and tasks, and a simplification of the organizational structure also enhance development speed, while an emphasis on the customer has an additional positive impact on new product profitability. Both new product speed and profitability increase firm financial performance. Our results further show that pioneers and fast followers should not select the same NPD acceleration approaches as the speed and profitability impact of the majority of the acceleration approaches depends on the new product strategy of the firm. These results are important as they provide guidance for pioneers and fast followers regarding which NPD acceleration approaches to select in order to enhance speed and profitability and, hence, firm financial performance.