Silver impregnation applied to striated muscle: The sarcoplasmic reticulum

The classical black reaction developed by Camillo Golgi is shown to impregnate the tubules and fenestrations of the sarcoplasmic reticulum (SR) in striated muscle. This is a double impregnation of chromate and silver, which usually fills extracellular spaces. The method is difficult insofar as long incubation times are required, and location of the successfully “stained” SR in plastic-embedded tissue blocks is unpredictable. The light microscope is absolutely necessary to find the good regions which can then be cut from the blocks in 1-μm-thick sections and examined in the electron microscope. Stereo pairs give the best results since these resolve overlap problems common to thick sections. A variety of artifacts are illustrated which can help avoid erroneous interpretations. The Golgi-“stained” SR shows this elusive network with unsurpassed contrast and should benefit the morphological studies of muscle-membrane enthusiasts.     

Dewatering behaviour of water treatment sludges associated with contaminated site remediation in Antarctica

Sludge reduction and dewatering is an important aspect of water and waste water treatment. This is especially true in the case of Australia's Antarctic contaminated site remediation program, where the reduction in volume of wastes to be returned to Australia can lead to significant transport and handling cost savings. The dewatering characterisation of water treatment sludges from an Antarctic contaminated site was conducted using a theory of suspension dewatering developed by Buscall, Landman and White. This theory uses fundamental material properties of compressibility and permeability to determine the diffusivity of a suspension. Diffusivity is a useful property that can be used to directly compare the dewaterability of various sludges. In this investigation, several water treatment sludges were collected and characterised in the field to determine the impact of temperature and additives on compressibility, permeability and diffusivity. The Antarctic sludges were found to be less compressible and less permeable than materials such as mineral suspensions and alum water treatment sludges. Compressibility was found to decrease with the addition of powdered coagulation aids such as bentonite and chitosan.     

Preparing for Program Accreditation Review Under ABET Engineering Criteria 2000: Choosing Outcome Indicators

This paper examines a variety of outcome indicators that might be used by an engineering program in meeting the assessment requirements of ABET Engineering Criteria 2000. Several categories of indicator are identified and key characteristics of these means of assessment are discussed. Also noted are some of the engineering applications of outcome indicators documented on the World Wide Web. Finally, the results of a recent telephone/fax survey on the use of outcome indicators in engineering program assessment are summarized.     

Influence of dispersant size on rheology of non-aqueous ceramic particle suspensions

The surface of alumina, which is hydrophilic in general, was made hydrophobic either by adsorption of polymer (phys-adsorption) or by an alkylation reaction with alcohol (chem-adsorption) to enable dispersion in dodecane. Hypermer A70 (8.2 nm) was used as the polymer and 1-octanol (1.2 nm), 1-decanol (1.5 nm) and 1-hexadecanol (2.5 nm) were used as the alcohol (values in brackets are the approximate thickness of the steric barrier). Rheological measurements of ceramic suspensions indicate that it is possible to achieve a high solid loading (50 vol.%) with relatively low viscosity (0.25 Pa s at 100 s^?1, the typical shear rate for pumping of liquids in pipes) as long as the stabilising molecule is large enough. The observed rheological behaviour fitted the Quemada viscosity model quite well when excluded volume effects were taken into account. Addition of 2.8 wt.% of Hypermer A70 with respect to weight of alumina was enough to stabilise the particles.     

Preparing for Program Accreditation Review Under ABET Engineering Criteria 2000: Creating a Database of Outcomes and Outcome Indicators for a Variety of Engineering Programs

ABET Engineering Criteria 2000 require a selection of outcomes and outcome indicators for each educational objective adopted by an engineering program. This paper describes a database created using Microsoft Access 97 © linking choices of program outcomes and choices of program outcome indicators for all of the accredited engineering programs in an academic institution. With this database, benchmarking searches can be conducted by type of engineering program, by choice of outcome, or by choice of outcome indicator. Several example searches are presented using data describing the engineering programs at Clemson University. A web-site address is given where copies of the Clemson database can be downloaded.     

Experimental validation of a 1-D continuous thickening model using a pilot column

Predictive modelling of solid–liquid separation can greatly assist the design and operation of thickening and filtration equipment, improving water recovery and reducing costs. A phenomenological model describing continuous thickening has been previously developed with primary inputs being the material properties, (compressive yield stress and hindered settling function) derived from routine laboratory batch settling and filtration tests. This work aimed to validate the model by operating a pilot column continuously and measuring the underflow solids. The column was operated at two different solid fluxes and several bed heights. Additionally, the influence of flocculation conditions (polymer dosage and residence time) on thickening performance were studied. The model predicted the experimental underflow solids concentration at a given flux. For the observed underflow solids concentration, the ratio of the actual to predicted flux was observed to be between a factor of 1 (accurate) and 10. The model was most accurate for the lowest bed heights. This work confirmed the model was able to correctly predict trends for the case where minimal bed height and shear forces are present. Deviation from the model is postulated to be due to changes in the dewatering properties of flocculated aggregates over time that are not adequately captured using conventional batch sedimentation tests. The data from these tests are traditionally used as a key input to thickening models.     

Bacterial hemagglutination by Neisseria gonorrhoeae

Direct bacterial hemagglutination was investigated with 20 clinical isolates of Neisseria gonorrhoeae. The hemagglutination tests were performed by both a macrotechnique with glass slides and a microtechnique with autotrays. Only organisms from form type 1 or 2 colonies caused hemagglutination. There was no statistical difference at a 10% or higher level in hemagglutination powers of type 1 and type 2 organisms, of male urethral and female cervical isolates, and of the eight major human blood types (ABO-Rh). Of seven erythrocyte species tested, only human cells were agglutinated. D-Mannose did not prevent the agglutination. Rabbit antigonococcal serum and high-titer antigonococcal human sera inhibited the hemagglutination. The results suggest the pili are the mediators of hemagglutination and that their specific agglutination of human erythrocytes may be a correlate of their adherence to human mucosal cells in natural infection. Also, although the procedure is presently insensitive, it is possible to detect human antigonococcal antibody by inhibition of direct bacterial hemagglutination.     

Intestinal absorption in Saudi Arabia: an evaluation of the one hour blood xylose test

The screening value of the one-hour blood xylose test, corrected for body surface area, was prospectively studied in Saudi Arabian adults and children under investigation for suspected intestinal malabsorption. Sensitivity of discrimination between patients with and without upper small bowel disease was 91%, compared to 85% for the five-hour urine xylose test. Primary small bowel disorder was rare. In a three-year review, no cases of adult coeliac disease or tropical sprue were found. The most common causes of malabsorption were intestinal tuberculosis, abdominal lymphoma and immunoproliferative small intestinal disease. Despite its acceptability as an index of proximal small bowel function, the blood xylose test alone is an inadequate screening test for any of these conditions.     

The influence of ionic strength and osmotic pressure on the dewatering behaviour of sewage sludge

In this work, we investigated the importance of osmotic pressure in the overall dewaterability behaviour of a biotic sludge. Biotic sludges, such as activated or digested sludge from waste water treatment, are known to be difficult to dewater, due to their high compressibility and their gel-like water retention capacity. These properties are partly attributed to the presence of surface charges, which are due to the biological nature and the presence of weakly charged extra-cellular polymeric substances. Both in filtration and centrifugation experiments, charge related effects were partly neutralised through a controlled increase in the bulk ionic strength by the addition of NaCl. It was observed that an increase in the bulk ionic strength brings about an increase in the final solid volume fraction upon constant pressure filtration or centrifugation. Increasing the ionic strength did not result in a more classical filtration behaviour, however. The results further suggested that with increasing total pressure, the relative importance of the osmotic pressure in the total resistance against compression diminishes, and that more structural effects dominate the solid stress at high pressures.