Evaluation of Halon 1301 test gas simulants: Enclosure leakage

Full discharge tests used in verification and quality assurance of total flooding Halon 1301 fire protection systems represent a large portion of the Halon 1301 emissions annually. It is, therefore, desirable to use a suitable simulant in these tests in view of the stratospheric ozone problem and current and future regulation of Halon 1301.Sulfur hexafluoride, SF₆, and chlorodifluoromethane, R-22, were identified as candidate simulants on the basis of their similarity in physical properties to Halon 1301. These two candidates were then evaluated on the basis of leakage from an enclosure.SF₆ was determined to be an excellent simulant for Halon 1301 when considering leakage from an enclosure. Further testing of SF₆ and R-22 is progressing on other important aspects of Halon 1301 systems; i.e., flow hydraulics and initial mixing.     

An Evaluation of Total Flooding High Expansion Foam Fire Suppression Systems for Machinery Space Applications

Full-scale fire tests were conducted to identify the fire extinguishing capabilities and limitations of High Expansion Foam Fire Suppression Systems (HEFFSS) in shipboard machinery space applications. A total of 35 tests were conducted in this evaluation utilizing the equipment and foam concentrates from three manufacturers. Each manufacturer was responsible for the design of their respective system. These designs were based on the minimum SOLAS/FSS Code requirements plus some additional capacity to provide a factor of safety for these tests. Each system was evaluated against the three large fire scenarios described in the International Maritime Organization's (IMO) gaseous agent test protocol (MSC/Circ. 848). The reason the HEFFSS test protocol (MSC/Circ. 670) was not used is discussed in the article. In addition to the tests in MSC/Circ. 848, parametric assessments of fill rate, fire size and type, and the use of inside air (the products of combustions) to make the foam were also conducted (one parameter for each of the three systems). In summary, there were significant differences in capabilities between the three systems. All three systems easily extinguished the pan fires included in this evaluation independent of the type of fuel (heptane or diesel). The differences in system capabilities were observed during the extinguishment of the spray fires (namely the heptane spray fires). The heptane spray fires presented a major challenge to the HEFFSS and in some cases, were not extinguished.     

Clean Agent System Utilizing FM-200® and Automatic Sprinkler System

Data processing and telecommunication (telco) facilities are commonly protected against fire with a clean agent system, an automatic sprinkler system, or with both a clean agent and an automatic sprinkler system. The degree of protection provided by these systems is vastly different, as is the cost incurred in employing these systems.Comparison testing of a clean agent system utilizing FM-200® (HFC-227ea) and an automatic sprinkler system was performed in order to illustrate the differences in the protection provided by gaseous clean agent systems and automatic sprinkler systems. The tests were performed in a simulated data processing/telecommunications facility, and examined the performance of the suppression systems on a plastics fire located inside a metal electronic equipment cabinet.In the clean agent system test, the fire was detected while it was small in size and was extinguished 17 sec after system actuation. Damage to the simulated facility and its contents was limited solely to the dislodging of several ceiling tiles near the clean agent nozzle, and a slight scorching of the cabinet containing the fuel array. The facility could be re-occupied and all systems within the facility, other than those damaged inside the cabinet involved in the fire, would be functional immediately following the extinguishment of the fire. Cleanup of the facility would not be required prior to its use following the fire event, as no residues were produced during extinguishment.Under the identical fire scenario, the automatic sprinkler system actuated approximately three minutes later than the clean agent system, and the fire was not extinguished by sprinkler system. The sprinkler system did achieve its primary objective of containing the fire to the room of origin and managing the temperatures at the ceiling to prevent structural damage and/or collapse, as the suspended ceiling remained intact, and the fire did not spread beyond the cabinet that contained the fuel array. Damage to the simulated facility was much more extensive than that resulting from the clean agent system test. All ceiling tiles were discolored and the tiles around the sprinkler heads that activated were warped and sagging. The walls were discolored throughout the entire simulated facility and a dark ring of varying intensity and width was observed just below the level of the suspended ceiling. Paper items located within the simulated facility suffered extensive water damage, and the simulated facility floor was covered in water containing large amounts of soot. Immediate reoccupation of the facility and resumption of business would be impossible under these circumstances, as the fire and smoke damage experienced by the facility and its contents would require the replacement of the facility walls, ceiling, and floor, and would likely require the replacement of water-damaged electronic equipment.The test results are discussed in detail as are the implications of the results in the design of fire protection systems for data processing and telecommunication type facilities.     

Film Formation Properties of Potato Starch Hydrolysates

Native and freeze‐dried potato starch granules were partially hydrolysed to produce maltodextrins with dextrose equivalents (DE) 10, 15 and 20. Freeze‐drying greatly improved the enzyme accessibility of the native granules. Film formation properties of the hydrolysates were examined. Films were prepared by water casting. Especially the maltodextrins, which were produced from the native starch, were very sticky materials and could not form any films. But after removing most of the soluble saccharides from the maltodextrins, good quality films were produced by dissolving the hydrolysate in water, casting on a Teflon mould and drying the solution.     

Visual Observation of Hydrolyzed Potato Starch Granules by α‐Amylase with Confocal Laser Scanning Microscopy

Porous starch was produced by digestion of freeze‐dried potato starch with α‐amylase from Bacillus sp. The surface structure of the granules became perforated and in the interior of the granules a capsule‐like cavity was formed, i.e. the hydrolyzed starch can be used as an encapsulant. The structure change of the granules was observed with confocal laser scanning microscopy and scanning electron microscopy. The degree of starch hydrolysis could be correlated with the Avrami equation. The activation energy of starch hydrolysis by α‐amylase was 83 kJ/mol.     

Protease-Activated Receptor 1 in Human Carotid Atheroma Is Significantly Related to Iron Metabolism,Plaque Vulnerability,and the Patient’s Age

(1) Background: Protease-activated receptor 1 (PAR1) has regulatory functions in inflammation, atherogenesis, and atherothrombosis. Chronic iron administration accelerates arterial thrombosis. Intraplaque hemorrhage and hemoglobin catabolism by macrophages are associated with dysregulated iron metabolism and atherosclerotic lesion instability. However, it remains unknown whether expressions of PAR1 in human atherosclerotic lesions are related to plaque severity, accumulation of macrophages, and iron-related proteins. We investigated the expression of PAR1 and its relation to the expression of ferritin and transferrin receptors in human carotid atherosclerotic plaques and then explored potential connections between their expressions, plaque development, and classical risk factors. (2) Methods: Carotid samples from 39 patients (25 males and 14 females) were immunostained with PAR1, macrophages, ferritin, and transferrin receptor. Double immunocytochemistry of PAR1 and ferritin was performed on THP-1 macrophages exposed to iron. (3) Results: PAR1 expression significantly increases with the patient’s age and the progression of human atherosclerotic plaques. Expressions of PAR1 are significantly correlated with the accumulation of CD68-positive macrophages, ferritin, and transferrin receptor 1 (TfR1), and inversely correlated with levels of high-density lipoprotein. In vitro, PAR1 is significantly increased in macrophages exposed to iron, and the expression of PAR1 is colocalized with ferritin expression. (4) Conclusions: PAR1 is significantly related to the progression of human atherosclerotic lesions and the patient’s age. PAR1 is also associated with macrophage infiltration and accumulation of iron metabolic proteins in human atherosclerotic lesions. Cellular iron-mediated induction of PAR1 and its colocalization with ferritin in macrophages may further indicate an important role of cellular iron in atherothrombosis.     

In vitro fermentation of polysaccharides of rye,wheat and oat brans and inulin by human faecal bacteria

The in vitro fermentabilities of rye, wheat and oat brans and of a commercial fibre preparation, inulin, were compared. The brans were first digested enzymatically to remove starch and protein. The digested brans and inulin were then fermented with human faecal inoculum. The progress of fermentation was studied by following the consumption of carbohydrates and the production of short‐chain fatty acids and gases. Inulin, a short fructose polymer, was consumed significantly faster than the more complex carbohydrates of cereal brans. Carbohydrates of oat bran (rich in β‐glucan) were consumed at a higher rate than those of rye and wheat brans (rich in arabinoxylan). In all brans, glucose was consumed faster than the other main sugars, arabinose and xylose, and arabinose was degraded only slightly. The total production of short‐chain fatty acids was slightly higher with oat bran than with rye and wheat brans and inulin. In the fermentation of inulin, relatively more butyric acid and less propionic acid were produced than in the fermentation of brans. The decrease in pH was also greater in the case of inulin. Wheat bran led to a slightly slower gas formation than rye and oat brans. Formation of gases was fastest and greatest in the case of inulin. In conclusion, rye, wheat and oat brans were fermented in a rather similar way. Fermentation of the brans was different from that of inulin. Cereal brans might serve as a more balanced source of dietary fibre supplement than gas‐producing, readily fermentable polysaccharides such as inulin. © 2000 Society of Chemical Industry     

Hypochlorite Oxidation of Barley and Potato Starch

The oxidation of barley and potato starches was studied using sodium hypochlorite as oxidant. The degree of oxidation, depolymerization during oxidation and gel formation of barley starch was compared with the properties of potato starch. The effect of oxidation on gelatinization of starches as well as on amylose-lipid complex of barley starch was also analyzed. Barley starch was not as easily oxidized as potato starch. In both starches depolymerization of amylopectin and amylose occurred during oxidation. Based on the dissociation enthalpy of amylose-lipid complex, the lipid-bound amylose in barley starch was readily oxidized. Oxidation decreased the gelling ability of barley starch. At high level of oxidation gel formation by potato starch was much slower and weaker than by barley starch.     

Transesterification of soy lecithin by lipase and phospholipase

Soy lecithin was modified by enzymatic transesterification in a solvent-free system. 1,3-SpecificRhizomucor miehei lipase was found to be efficient in the transesterification with lauric acid and oleic acid, where oleic acid was more incorporated into soy lecithin. Phospholipase A₂ incorporated lauric acid hardly at all, but it hydrolyzed lecithin efficiently. The mixture of lipase and phospholipase A₂ (1:1, w/w) incorporated lauric acid to the same extent as did 1,3-specific lipase alone at the same total enzyme concentration. The main fatty acids replaced were palmitic and linoleic acids by 1,3-specific lipase and its mixture with phospholipase A₂, and linoleic and linolenic acids by phospholipase A₂ alone, suggesting an improved oxidative stability of the resulting product. Hydrolysis could not be prevented, but it could be regulated by incubation time and by enzyme dosage. The minimal water content for significant incorporation of lauric acid into lecithin was below 0.5% of the weight of the reaction mixture.     

Using line integral convolution for flow visualization: curvilineargrids, variable-speed animation, and unsteady flows

Line integral convolution (LIC), introduced by Cabral and Leedom (1993) is a powerful technique for imaging and animating vector fields. We extend the LIC technique in three ways. Firstly the existing algorithm is limited to vector fields over a regular Cartesian grid. We extend the algorithm and the animation techniques possible with it to vector fields over curvilinear surfaces, such as those found in computational fluid dynamics simulations. Secondly we introduce a technique to visualize vector magnitude as well as vector direction, i.e., variable-speed flow animation. Thirdly we show how to modify LIC to visualize unsteady (time dependent) flows. Our implementation utilizes texture-mapping hardware to run in real time, which allows our algorithms to be included in interactive applications