Treatment of naphthalene-2-sulfonic acid from tannery wastewater by a granular activated carbon fixed bed inoculated with bacterial isolates Arthrobacter globiformis and Comamonas testosteroni

The kinetics of naphthalene-2-sulfonic acid (2-NSA) adsorption by granular activated carbon (GAC) were measured and the relationships between adsorption, desorption, bioavailability and biodegradation assessed. The conventional Langmuir model fitted the experimental sorption isotherm data and introduced 2-NSA degrading bacteria, established on the surface of the GAC, did not interfere with adsorption. The potential value of GAC as a microbial support in the aerobic degradation of 2-NSA by Arthrobacter globiformis and Comamonas testosteroni was investigated. Using both virgin and microbially colonised GAC, adsorption removed 2-NSA from the liquid phase up to its saturation capacity of 140 mg/g GAC within 48 h. However, between 83.2% and 93.3% of the adsorbed 2-NSA was bioavailable to both bacterial species as a source of carbon for growth. In comparison to the non-inoculated GAC, the combination of rapid adsorption and biodegradation increased the amount (by 70–93%) of 2-NSA removal from the influent phase as well as the bed-life of the GAC (from 40 to >120 d). A microbially conditioned GAC fixed-bed reactor containing 15 g GAC removed 100% 2-NSA (100 mg/l) from tannery wastewater at an empty bed contact time of 22 min for a minimum of 120 d without the need for GAC reconditioning or replacement. This suggests that small volume GAC bioreactors could be used for tannery wastewater recycling.

Longitudinal excursion and strain in the median nerve during novel nerve gliding exercises for carpal tunnel syndrome

Nerve and tendon gliding exercises are advocated in the conservative and postoperative management of carpal tunnel syndrome (CTS). However, traditionally advocated exercises elongate the nerve bedding substantially, which may induce a potentially deleterious strain in the median nerve with the risk of symptom exacerbation in some patients and reduced benefits from nerve gliding. This study aimed to evaluate various nerve gliding exercises, including novel techniques that aim to slide the nerve through the carpal tunnel while minimizing strain (sliding techniques). With these sliding techniques, it is assumed that an increase in nerve strain due to nerve bed elongation at one joint (e.g., wrist extension) is simultaneously counterbalanced by a decrease in nerve bed length at an adjacent joint (e.g., elbow flexion). Excursion and strain in the median nerve at the wrist were measured with a digital calliper and miniature strain gauge in six human cadavers during six mobilization techniques. The sliding technique resulted in an excursion of 12.4 mm, which was 30% larger than any other technique (p 0.0002). Strain also differed between techniques (p 0.00001), with minimal peak values for the sliding technique. Nerve gliding associated with wrist movements can be considerably increased and nerve strain substantially reduced by simultaneously moving neighboring joints. These novel nerve sliding techniques are biologically plausible exercises for CTS that deserve further clinical evaluation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:972-980, 2007

Standing wave bed forms at Plage de la Grande Roche, le Verdelet, Pléneuf-Val-André, Cote d’Armor (France)

Coastal Photograph by Hubert Chanson This photograph of standing wave bed forms was taken at very low tide. The tidal range was 10 m. The bed forms were located on the island of Le Verdelet, in a channel between Le Grande Jaune and Le Verdelet. It is likely that these standing wave bed forms were formed during transcritical shallow water flows at the end of ebb tide. The author’s watch is in the foreground for scale. (Coastal Photograph by Hubert Chanson, Division of Civil Engineering, the University of Queensland, Brisbane, Queensland 4072, Australia.)

Pavilions and outdoor seating area, Lake Weyba House, Sunshine Coast

As seen from back of bedroom pavilion, looking towards main pavilion. Day bed alcove to bedroom in foreground.

Negative stress and the outcome of treatment for binge eating

This study investigated the ability of negatively versus positively perceived stress to predict outcome of treatment for binge eating disorder (BED). Participants were 62 obese women satisfying the DSMIV research criteria for BED. Stress was measured using an instrument based on the Recent Life Change Questionnaire (RLCQ). Participants experiencing high negative stress during the study period reported a binge eating frequency three times greater than that reported by subjects experiencing low negative stress (2.14 vs. 0.65 binge-days/week). Negative stress predicted how fast an individual would reduce binge eating and demonstrated more predictive power than positive stress.

Enzyme deactivation in fixed bed reactors with michaelis-menten kinetics

Rate expression for enzyme poisoning which are consistent with a Michaelis-Menten main reaction are used to analyze the performance of a fixed bed reactor containing immobilized enzyme. When enzyme deactivation results from the irreversible bonding of a product molecule to an existing substrate-enzyme complex, it is shown that minimum enzyme activity can occur in the interior of the bed, well away from the ends. This suggests that bed sectioning techniques may enable direct evaluation of fundamental poisoning mechanisms.

Fixed bed reactors with catalyst poisoning - first order kinetics.

The long performance of an isothermal fixed bed reactor undergoing catalyst poisoning is theoretically analyzed using the dispersion model. First order reaction with dth order deactivation is assumed and the model equations are solved by matched asymptotic expansions for large Peclet number. Simple closed-form solutions, uniformly valid in time, are obtained.

Hysteresis and phase transitions in a single partially internally wetted catalyst pellet: Thermogravimetric studies

The hydrogenation of cyclohexene over palladium supported in a microporous gamma-alumina pellet is studied thermogravimetrically with a view to measuring the extent of partial internal wetting associated with the different steady state branches. As many as three steady state branches having significantly different degrees of internal wetting and reaction rates, with transitions between them, are confirmed from observations of catalyst weight change. It is seen that with reduction in catalyst activity the middle branch, obtained by condensation from a vapor filled pellet, is much more prominent without showing an evaporative transition for the range of hydrogen partial pressures used here. The catalyst activity is therefore an important parameter affecting the structure of the steady state branches. Hysteresis effects are found to occur, and the thermogravimetric results also confirm the importance of history in determining the catalyst state. The measured degree of wetting is in accordance with that estimated from a mathematical model incorporating capillary condensation effects in addition to reaction-diffusion phenomena. The same model also satisfactorily interprets the reaction rate variations and transitions seen in the present work.

A comparative study of the fluidized-bed coating of cylindrical metal surfaces with various thermoplastic polymer powders

This paper reports the results of an experimental investigation into the fluidized-bed coating of cylindrical metal specimens using two types of thermoplastic powders, Rilsan(R) PA11, a nylon-11 powder produced by Elf Atochem, France and Cotene(TM) 4612, a linear low density polyethylene powder produced by J.R Courtenay (New Zealand). The effects of dipping time, preheat temperature and particle size distribution on coating thickness and surface finish were investigated. Consistent trends in coating thickness growth with dipping time were obtained for both nylon-11 and polyethylene powders with increases in coating thickness with preheat temperature. For the same preheat temperature, the lower melting point of polyethylene results in thicker coatings compared to those of nylon-11. There is a negligible change in the coating thickness for sieved powders compared to that for unsieved powders. A pre-heat temperatures of between 240 degrees C and 300 degrees C is necessary to achieve an acceptable surface finish with both nylon-11 and polyethylene powders. To minimize errors in achieving the desired coating thickness, dipping times shorter than 2 s are not recommended. The use of graphs of coating thickness versus dipping time in combination with the coating surface roughness plots presented in this paper enable the optimal choice of pre-heat temperature and dipping time to achieve acceptable surface finish. (C) 1999 Elsevier Science S.A. All rights reserved.

A comparative study of N2O conversion to N-2 over Co/AC and Cu/AC catalysts

Catalytic conversion of N2O to N-2 over Cu- and Co-impregnated activated carbon catalysts (Cu/AC and Co/AC) was investigated. Catalytic activity measurements were carried out in a fixed-bed flow reactor at atmospheric pressure. The catalysts were characterized by N-2 adsorption, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). This study aimed to provide insights into the following aspects: the metal dispersion, changes in pore structure, influence of catalyst loading on reaction, and reaction mechanism. Increasing loading of Co or Cu led to decreasing dispersion, but 20 wt % loading was an upper limit for optimal activities in both cases, with too high loading causing sintering of metal. Co exhibited a relatively better dispersion than Cu. Impregnation of metal led to a large decrease in surface area and pore volume, especially for 30 wt % of loading. 20 wt % of loading has proved to be the optimum for both Cu and Co, which shows the highest activity. Both N2O-Co/AC and -Cu/AC reactions are based upon a redox mechanism, but the former is limited by the oxygen transfer from catalysts to carbon, while N2O chemisorption on the surface of Cu catalyst controls the latter. The removal of oxygen from cobalt promotes the activity of Co/AC, but it is beneficial for Cu/AC to keep plenty of oxygen to maintain the intermediate oxidation of copper-Cu1+. The different nature of the two catalysts and their catalytic reaction mechanisms are closely related to their different electronegativities.

Effects of acid treatments of carbon on N2O and NO reduction by carbon-supported copper catalysts

The influences of HCl, HNO3 and HF treatments of carbon on N2O and NO reduction with 20 wt% Cu-loaded activated carbon were studied. The order of activity in both N2O and NO is as follows: Cu20/AC-HNO3>Cu20/AC>Cu20/AC-HF>Cu20/AC-HCl. The same sequence was also observed for the amount of CO2 evolved during TPD experiments of supports acid for the catalyst dispersion. On the other hand, N2O exhibited a higher reaction rate than NO and a higher sensitivity to acid treatments, and the presence of gas-phase O-2 had opposite effects in N2O and NO reduction. The key role of carbon surface chemistry is examined to rationalize these findings and the relevant mechanistic and practical implications are discussed. The effects of oxygen surface groups on the pore structure of supports and catalysts are also analyzed, (C) 2000 Elsevier Science Ltd. All rights reserved.

Effects of promoters on catalytic activity and carbon deposition of Ni/gamma-Al2O3 catalysts in CO2 reforming of CH4

Catalytic reforming of methane with carbon dioxide was studied in a fixed-bed reactor using unpromoted and promoted Ni/gamma-Al2O3 catalysts. The effects of promoters, such as alkali metal oxide (Na2O), alkaline-earth metal oxides (MgO, CaO) and rare-earth metal oxides (La2O3, CeO2), on the catalytic activity and stability in terms of coking resistance and coke reactivity were systematically examined. CaO-, La2O3- and CeO2-promoted Ni/gamma-Al2O3 catalysts exhibited higher stability whereas MgO- and Na2O-promoted catalysts demonstrated lower activity and significant deactivation. Metal-oxide promoters (Na2O, MgO, La2O3, and CeO2) suppressed the carbon deposition, primarily due to the enhanced basicities of the supports and highly reactive carbon species formed during the reaction. In contrast, CaO increased the carbon deposition; however, it promoted the carbon reactivity. (C) 2000 Society of Chemical Industry.