Knowledge-based scheduling in flexible manufacturing systems: An integration of pattern-directed inference and heuristic search

This paper presents a knowledge-based scheduling approach based on the problem-solving techniques developed in artificial intelligence. The approach is based on three key techniques. The first is the pattern-directed inference technique to capture the dynamic nature of the scheduling environment. The second is the non-linear planning technique to coordinate manufacturing processes and resource assignments. The third technique is the A? search algorithm to expedite the searching procedure. It models the scheduling process by state-space transitions; the job routing is obtained through selecting a sequence of scheduling operators guided by heuristics. Keeping track of the manufacturing system by a symbolic world model, this approach is adaptive to such environmental changes as new job arrivals and machine breakdowns, suitable for making real-time scheduling decisions.     

TISSUE DISTRIBUTION AND METABOLISM OF AFLATOXIN B1-14C IN LAYER CHICKENS

The effects of administering low levels of aflatoxin B₁-¹⁴C by crop intubation daily for 14 days to layer chickens were determined. Studies on the distribution of ¹⁴C in the blood, selected organs, tissues, eggs and excreta were conducted. No toxic effects were observed in layer chickens during the course of the experiment. The layer chickens excreted 92.15% of the ¹⁴C administered. Of the ¹⁴C retained, 19.5, 16.1, 3.9, 7.2, 26.4 and 26.9% were detected in the blood, liver, heart, gizzard, breast and leg, respectively. No radioactivity was detected in egg samples collected. Chemical assay of those samples demonstrating radioactivity revealed that 81.2% of the radioactivity in these substrates was soluble in aqueous extracts while approximately 10% was ex tractable by classical extraction procedures. Treatment of the aqueous extracts for conjugated steroids by treatment with Beta-glucuronidase revealed that 31.5% of the ¹⁴C detected in the aqueous extract was a liberated glucuronide conjugate of aflatoxin M₁−¹⁴C     

FREQUENCY OF SALMONELLA, CAMPYLOBACTER, LISTERIA AND ENTEROBACTERIACEAE DETECTION IN COMMERCIALLY COOL WATER-WASHED SHELL EGGS

The effect of cool water washing on shell egg temperature and pathogen detection was examined. Three temperature schemes were utilized in commercial dual washer systems: (1) HH = 48.9C, 48.9C; (2) HC = 48.9C, 23.9C; and (3) CC = 23.9C, 23.9C. HH eggsmaintainedthe highest surface temperature (26.25C in‐line, 20.25C off‐line and 23.25C combined, P < 0.05). The lowest temperatures were found in the CC eggs (21.25C in‐line, 17.25C off‐line and 19.25C combined). The frequency of Enterobacteriaceae detection in shell and membrane emulsions was greatest for the CC eggs (P < 0.05 for in‐line and combined). There was no difference in Enterobacteriaceae detection for the off‐line facility. Salmonella was detected in three of 384 samples from the in‐line facility. They were found in HC (2) and CC (1) shell emulsions. Two of 384 samples were positive for Campylobacter from the in‐line facility (CC). Three wash water samples were positive for Listeria in the off‐line facility (1 HC, 2 CC). No pathogens were detected in the egg contents during this study. The results of this study indicate that warm followed by cool water washing has the potential of decreasing egg temperature while maintaining surface microbiology at an acceptable level.     

Analysis of the anthocyanin composition of Cabernet Sauvignon and Portugieser wines provides an objective assessment of the grape varieties

This paper presents data on the ratios of acetylated to p -coumaroylated anthocyanins of authentic and unadulterated trade samples of 71 Cabernet Sauvignon and 40 Portugieser winegrape varieties. The relative peak areas of nine characterising anthocyanins were determined by a standardised and validated HPLC-method. The 95%-confidence ranges calculated from the data ranged from 2.9 to 5.7 for the Cabernet Sauvignon wines and from 0.7 to 1.7 for the Portugieser wines. The rule that individual anthocyanin components are normally distributed was also confirmed for wines vinified from Gamay and Kadarka (Gamza) grape varieties.     

EFFECTS OF DARK STORAGE TIME AND UV-FILTERED FLUORESCENT LIGHTING DURING DISPLAY ON COLOR STABILITY OF HIGH-OXYGEN MODIFIED ATMOSPHERE PACKAGED GROUND BEEF

Effects of temperature (OC and 4.4C) during dark storage (days 2-9) and display in non-UVand UV-filtered fluorescent lighting on color stability of high-O₂ modified atmosphere packaged "case ready" ground beef was evaluated. Minimal shift in headspace O₂ and CO₂ concentrations occurred during 9 days of storage and display. By day 3, product stored at 4.4C lost redness (Hunter +a) faster than that held at OC. Visual panel ratings for lean color decreased (P > 0.05) after 7 days but were not affected by storage temperature. When packages stored 2, 4, or 6 days at OC were displayed in light, Hunter +a values did not decline (P <0.05) for the first day and in several instances were maintained for 2 days. Panel evaluations of displayed product substantiated high maintenance of redness of lean color. UV-filtering of fluorescent lighting was not necessary for color stability of ground beef during display.     

In Vitro Fermentabilities of Purified Fiber Supplements

Six commonly used dietary fiber supplements (pectin, tragacanth gum, psyllium gum, guar gum, soy fiber and cellulose) were fermented in vitro with human fecal microbiota for 4, 8,12, and 24 hr. Short chain fatty acids (SCFA), hydrogen and methane productions, and neutral-detergent fiber digestibility differed significantly with fiber source. The most rapid fermentation rate was with pectin followed by psyllium gum, tragacanth gum, guar gum, soy fiber, and finally cellulose. Such differences in fermentability should be considered when food products are formulated. Dietary fiber source and intake may also affect breath hydrogen measurements and estimates of available carbohydrate malabsorption.     

Application of Ellipsometry to Evaluate Surface Cleaning Effectiveness

Mechanisms associated with the cleaning of food contact surfaces are not completely understood, and attempts to evaluate or improve cleaning processes are consequently hindered. The usefulness of ellipsometry as a technique to rate efficiency of different cleaning methods with respect to ability to remove milk soils from various materials is described. Film properties obtainable with ellipsometry, including a measure of the apparent mass remaining on a given surface after cleaning, can be used to provide an indication of the relative effectiveness of a cleaning method. This information contributes to establishment of criteria by which the effectiveness of a cleaning operation can be judged.     

QUALITY OF MEAT PRODUCTS DURING REFRIGERATED AND ULTRA-CHILLED STORAGE

Standard domestic refrigerators store food between 1 and 5C (33.8–41F). A manufacturer recently developed a refrigerator capable of storing food in the “ultra‐chilled region” (?3 to ?7C) and claimed that storage of fresh meat in this region better maintains quality. To understand quality in terms of chemical reaction rates, microbial growth and texture and flavor changes, three common consumer meat products – steak, ground beef patty and salmon – were stored for a selected period of time, as determined by microbial testing, in five refrigerator models with different environmental conditions (constant temperature and temperature fluctuation). At the end of the storage period, consumer panelists assessed the quality of the cooked samples by ranking them according to preference. In addition, instruments were used to measure the color and shear cutting force (for steak only) of each sample. Results from the consumer Ranking R‐Index Test indicate that panelists preferred samples stored under or near ultra‐chilled conditions rather than samples stored under standard refrigerated conditions. The ultra‐chilled samples not only had higher panelist rankings and more favorable comments, but also had lower microbial aerobic plate counts. The instrument readings, however, highly varied and did not correlate well with sensory data.     

THE THROMBORESISTANCE OF A HEPARIN-POLYVINYL ALCOHOL HYDROGEL†

Heparin immobilized onto polyvinyl alcohol (PVA) by action of glutaraldehyde has been shown to be biologically active in a novel parallel flow arteriovenous shunt in dogs. The hepann-PVA hydrogel originally devised by Merrill and his collaborators was applied as a coaling to chromic acid etched polyethylene lubing. A pair of Y-connectors was used to divert < 2% of the flow in the AV shunt through the heparinized tube, which remained patent for longer Ihan two hours while a control tube without heparin was occluded within 30 minutes at a main shunt flow rate of ～l50mL/min. This enhanced patency was achieved without significant release from the surface, consistent with earlier experiments attributing the thromboresistance of the heparin-PVA hydrogel to the formation of a surface bound inactive thrombin-antithrombin III complex. Radiolabelled thrombin adsorbed onto beads made from the gel was readily displaced by arvinized plasma, indicating that the inactive complex was not itself permanently bound to the surface.

These results demonstrate the utility of Merrill's hydrogel for preparing materials with potential long lerm thromboresistance and for testing the validity of the hypothesized limitations to the long term use of immobilized heparin.     

Immunohistochemistry of GluR1 subunits of AMPA receptors of rat cerebellar nerve cells

The localization of GluR1 subunits of ionotropic glutamate receptors in the glial cells and inhibitory neurons of cerebellar cortex and their association with the climbing and parallel fibers, and basket cell axons were studied. Samples of P14 and P21 rat cerebellar cortex were exposed to a specific antibody against GluR1 subunit(s) of AMPA receptors and were examined with confocal laser scanning microscopy. GluR1 strong immunoreactivity was confined to Purkinje cell and the molecular layer. Weak GluR1 immunoreactivity was observed surrounding some Golgi cells in the granule cell layer. Intense GluR1 immunoreactivity was localized around Purkinje, basket, and stellate cells. Purkinje cells expressed strong GluR1 immunoreactivity surrounding the cell body, primary dendritic trunk and secondary and tertiary spiny dendritic branches. Marked immunofluorescent staining was also detected in the Bergmann glial fibers at the level of middle and outer third molecular layer. Positive immunofluorescence staining was also observed surrounding basket and stellate cells, and in the capillary wall. These findings suggest the specific localization of GluR1 subunits of AMPA receptors in Bergmann glial cells, inhibitory cerebellar neurons, and the associated excitatory glutamatergic circuits formed by climbing and parallel fibers, and by the inhibitory basket cell axons