Dewatering of Sewage Sludge

Dewatering of sewage sludges is usually carried out using belt filter presses or centrifuges. The ability to remove water from sludges by mechanical dewatering is a property of both the sludge and the equipment used for dewatering. Newer high-solids centrifuges can remove more water than a belt press but require a higher chemical conditioning dose. The Gt value, the product of the mean velocity gradient and the shear time, has been found to be a useful parameter for characterizing the shear in mechanical dewatering equipment. Dewatering can be considered a two-step process, filtration followed by expression. The expression step is the most important of these and the benefits of various sludge processing techniques and conditioning chemical types remains a fruitful area of research.     

Characterization of synthetic and activated sludge and conditioning with cationic polyelectrolytes

This study investigates the effect of cationic polyelectrolytes on the final properties of synthetic and activated sludge. Synthetic sludge was prepared according to established procedures. Activated sludge was produced in a labscale, continuous-flow reactor which was fed with live activated sludge from a waste-water treatment plant. Capillary suction time (CST) was used to evaluate the sludge dewatering behaviour. The results from experiments indicated that the cationic polyelectrolytes had a critical effect on sludge dewatering, and made an improvement in the final properties of sludge. The two types of sludge have very similar dewatering characteristics after cationic polymer conditioning. The development of synthetic sludge is suggested also to be a possible surrogate for studying the final properties of activated sludge.     

Viscosity measurements and empirical predictions for fluxed Australian bituminous coal ashes

Recent interest in the suitability of Australian bituminous coals for use in integrated gasification-combined cycle (IGCC) technologies has provided the opportunity to determine viscosity data for a range of coal ashes slags fluxed with limestone at the tapping temperatures of entrained flow gasifiers. Experimental viscosity measurements have been made over a range of slag compositions covering the anorthite region at the 0–2.5, 2.5–5, 5–7.5 and 7.5–10 wt% FeO levels of the quaternary SiO₂–Al₂O₃–CaO–FeO system. Contour plots of viscosities at 1450°C for the four FeO ranges are presented as an example for predicting slag behaviour in entrained flow gasifiers. The viscosity measurements have also been fitted empirically using a modified Urbain treatment to give separate models for the four FeO levels. Polynomial expressions are given for the evaluation of viscosities covering the temperature range 1400–1550°C for slags within the compositional range used in the derivation.     

Learning-Based Vertebra Detection and Iterative Normalized-Cut Segmentation for Spinal MRI

Automatic extraction of vertebra regions from a spinal magnetic resonance (MR) image is normally required as the first step to an intelligent spinal MR image diagnosis system. In this work, we develop a fully automatic vertebra detection and segmentation system, which consists of three stages; namely, AdaBoost-based vertebra detection, detection refinement via robust curve fitting, and vertebra segmentation by an iterative normalized cut algorithm. In order to produce an efficient and effective vertebra detector, a statistical learning approach based on an improved AdaBoost algorithm is proposed. A robust estimation procedure is applied on the detected vertebra locations to fit a spine curve, thus refining the above vertebra detection results. This refinement process involves removing the false detections and recovering the miss-detected vertebrae. Finally, an iterative normalized-cut segmentation algorithm is proposed to segment the precise vertebra regions from the detected vertebra locations. In our implementation, the proposed AdaBoost-based detector is trained from 22 spinal MR volume images. The experimental results show that the proposed vertebra detection and segmentation system can achieve nearly 98% vertebra detection rate and 96% segmentation accuracy on a variety of testing spinal MR images. Our experiments also show the vertebra detection and segmentation accuracies by using the proposed algorithm are superior to those of the previous representative methods. The proposed vertebra detection and segmentation system is proved to be robust and accurate so that it can be used for advanced research and application on spinal MR images.     

Ex vivo and in vitro testis and ovary explants: utility for identifying steroid biosynthesis inhibitors and comparison to a Tier I screening battery

Retinal ganglion cell (RGC) axons in lizards (reptiles) were found to regenerate after optic nerve injury. To determine whether regeneration occurs because the visual pathway has growth-supporting glia cells or whether RGC axons regrow despite the presence of neurite growth-inhibitory components, the substrate properties of lizard optic nerve myelin and of oligodendrocytes were analyzed in vitro, using rat dorsal root ganglion (DRG) neurons. In addition, the response of lizard RGC axons upon contact with rat and reptilian oligodendrocytes or with myelin proteins from the mammalian central nervous system (CNS) was monitored. Lizard optic nerve myelin inhibited extension of rat DRG neurites, and lizard oligodendrocytes elicited DRG growth cone collapse. Both effects were partially reversed by antibody IN-1 against mammalian 35/250 kD neurite growth inhibitors, and IN-1 stained myelinated fiber tracts in the lizard CNS. However, lizard RGC growth cones grew freely across oligodendrocytes from the rat and the reptilian CNS. Mammalian CNS myelin proteins reconstituted into liposomes and added to elongating lizard RGC axons caused at most a transient collapse reaction. Growth cones always recovered within an hour and regrew. Thus, lizard CNS myelin and oligodendrocytes possess nonpermissive substrate properties for DRG neurons--like corresponding structures and cells in the mammalian CNS, including mammalian-like neurite growth inhibitors. Lizard RGC axons, however, appear to be far less sensitive to these inhibitory substrate components and therefore may be able to regenerate through the visual pathway despite the presence of myelin and oligodendrocytes that block growth of DRG neurites.     

DEVELOPMENT OF THICK THERMAL BARRIER COATINGS FOR DIESEL APPLICATIONS

An integrated process for the design, plasma spray processing, laboratory evaluation, rig test verification and hardware evaluation of thermal barrier coatings for diesel engine applications is described. This method relies heavily on a thorough understanding of the process at each step. The properties and residual stress condition of the coating were modified to meet design criteria through control of the various plasma spray processing parameters. Coating uniformity and repeatability issues were also addressed by adjusting the process conditions to properly account for the specific geometric features of the substrate. These steps are described in detail with particular emphasis on the effect of the process on the coating characteristics. It is shown that a thick thermal barrier can be produced which is durable under accelerated engine test conditions through proper choice of material and processing parameters.     

Effects of hindlimb contraction on pressor and muscle interstitial metabolite responses in the cat

We used the microdialysis technique to measure the interstitial concentration of several putative metabolic stimulants of the exercise pressor reflex during 3- and 5-Hz twitch contractions in the decerebrate cat. The peak increases in heart rate and mean arterial pressure during contraction were 20 +/- 5 beats/min and 21 +/- 8 mmHg and 27 +/- 9 beats/min and 37 +/- 12 mmHg for the 3- and 5-Hz stimulation protocols, respectively. All variables returned to baseline after 10 min of recovery. Interstitial lactate rose (P < 0. 05) by 0.41 +/- 0.15 and 0.56 +/- 0.16 mM for the 3- and 5-Hz stimulation protocols, respectively, and were not statistically different from one another. Interstitial lactate levels remained above (P < 0.05) baseline during recovery in the 5-Hz group. Dialysate phosphate concentrations (corrected for shifts in probe recovery) rose with stimulation (P < 0.05) by 0.19 +/- 0.08 and 0.11 +/- 0.03 mM for the 3- and 5-Hz protocols. There were no differences between groups. The resting dialysate K+ concentrations for the 3- and 5-Hz conditions were 4.0 +/- 0.1 and 3.9 +/- 0.1 meq/l, respectively. During stimulation the dialysate K+ concentrations rose steadily for both conditions, and the increase from rest to stimulation (P < 0.05) was 0.57 +/- 0.19 and 0.81 +/- 0.06 meq/l for the 3- and 5-Hz conditions, respectively, with no differences between groups. Resting dialysate pH was 6.915 +/- 0.055 and 6.981 +/- 0.032 and rose to 7.013 (P < 0.05) and 7.053 (P < 0.05) for the 3- and 5-Hz conditions, respectively, and then became acidotic (6. 905, P < 0.05) during recovery (5 Hz only). This study represents the first time simultaneous measurements of multiple skeletal muscle interstitial metabolites and pressor responses to twitch contractions have been made in the cat. These data suggest that interstitial K+ and phosphate, but not lactate and H+, may contribute to the stimulation of thin fiber muscle afferents during contraction.     

Independent isolates of the emerging subgroup J avian leukosis virus derive from a common ancestor

A new subgroup of avian leukosis virus (ALV) that includes a unique env gene, designated J, was identified recently in England. Sequence analysis of prototype English isolate HPRS-103 revealed several other unique genetic characteristics of this strain and provided information that it arose by recombination between exogenous and endogenous virus sequences. In the past several years, ALV J type viruses (ALV-J) have been isolated from broiler breeder flocks in the United States. We were interested in determining the relationship between the U.S. and English isolates of ALV-J. Based on sequence data from two independently derived U.S. field isolates, we conclude that the U.S. and English isolates of ALV-J derive from a common ancestor and are not the result of independent recombination events.