bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat transmission in fire test furnaces
Authors: Sultan M. A. , Harmathy T. Z. , Mehaffey J. R. 
Published: December 2004

AbstractThis theoretical and experimental study, complementary to that discussed in Reference 1, examines those factors that affect the ‘test efficiency’ in fire resistance testing. Convective heat transfer in the test chamber may become an essential part of the heat transmission process if, due to small furnace size or non‐luminous furnace gases, the radiative transmission is not sufficiently intense. The standard technique of measuring and controlling the temperature conditions in the furnace chamber, though not in line with strict scienctific practices, appears to provide insurance against poor test result. A calibration procedure is described for checking the adequacy of fire resistance test facilities and some solutions presented for improving the test efficiency.
ISO ignitability test and proposed criteria
Authors: Bluhme D. A. 
Published: December 2004

AbstractHaving characterized the current classification of building materials in Scandinavia the use of the International Standards Organization ignitability test for classifying coverings, linings and materials is discussed. Further evidence for the assumption of a linear function for 1/tig (where tig is the time for sustained surface ignition) versus irradiance was gained for a number of materials, mainly wood‐based. This has been utilized in forecasting the ignitability behaviour in the new test by correlation of classes. Through definition of two borderline segments a simple table giving proposed criteria for tig is obtained.
Experimental observations of the effect of pressure and buoyancy on cellulose co‐current smoldering
Authors: Newhall J. L. , Fernandez‐Pello A. C. , Pagni P. J. 
Published: December 2004

AbstractAn experimental study has been performed to determine the potential effect of buoyancy on the rate of propagation of a co‐current smolder reaction through a porous solid fuel, and the range of flow velocities where buoyancy effects are significant. In the co‐current smolder reaction, the fuel and oxidizer enter the reaction zone from the same direction. In the present experiments this is accomplished by initiating the reaction at the top of the fuel bed, α‐cellulose packed at a void fraction 0.85, so that the smolder wave propagates downward opposing an upward forced flow of air. Since in a stratified density field, buoyancy is proportional to the product of gravity and density difference, buoyancy can be controlled by varying either the gravity vector or the gas density. In this study the latter method is followed, varying gas density through the ambient pressure at which the experiments are performed. The smolder velocity is measured for air flow rates varying from 0.2 to 6 gm−2s−1 at constant ambient pressures of 0.6, 0.8 and 1 atm. The results show that for flow rates larger than 1 gm−2s−1 the smolder velocity increases linearly with the air flow rate but is independent of pressure. The reaction peak temperature is weakly dependent on flow rate and independent of pressure. For the present experimental conditions the effect of buoyancy is only observed at very low air flow rates. The mechanisms by which it affects the smolder process appears to be by altering the transport of air to the reaction zone from upstream and downstream of the reaction.
The behaviour of commercially important diisocyanates in fire conditions. Part 2: Polymeric diphenyl methane‐4,4′‐diisocyanate (pmdi)
Authors: Marlair G. , Prager F. H. , Sand H. 
Published: December 2004

AbstractThe behaviour of polymeric diphenyl methane‐4,4′‐diisocyanate (PMDI) is described when examined in a laboratory small‐scale test for its reaction to fire (ease of ignition; heat release and toxic gas production). Full‐scale real fire scenarios have also been staged to predict events if (1) drumstock PMDI and (2) sizeable pools of liquid PMDI become enveloped in a fire. PMDI requires a stimulus (e.g. heat) before it will ignite from an applied flame. It then burns in a self‐sustaining manner for a few minutes, during which main emissions take place. Then a polymerization reaction begins, producing a low density non‐burning residue, which progressively dampens down the burning events by blanket action. Residues of 30–80% sample weight were recorded. The major toxic gas produced is carbon monoxide, though free isocyanate is to be expected in the early stages of the fire, and hydrogen cyanide could be important, especially in well‐developed fire conditions. Firefighters should therefore wear full protective clothing and fresh‐air breathing equipment. Events when drums of PMDI are exposed to fire depend heavily on the characteristics of the containers, with some rupture steps proceeding with considerable violence. Drumstock PMDI should be stored separately from easily ignitable materials.
Developing rational, performance‐based fire safety requirements in model building codes
Authors: Bukowski Richard W. , Babrauskas Vytenis 
Published: December 2004

AbstractThe technical and philosophical basis for performance‐based assessment of building fire performance is reviewed. A strategy for the evolution of a performance code is described. Current efforts toward the development of performance codes in the USA and Japan are reviewed. Recommendations for critical steps necessary to advance the development and acceptance of performance codes are presented. The table of contents of the Japanese risk methodology for assessing ‘Article 38 equivalencies’ is included in an appendix.
Fire conditions for smoke toxicity measurement
Authors: Gann Richard G. , Babrauskas Vytenis , Peacock Richard D. , Hall John R. 
Published: December 2004

AbstractThis paper identifies those fire conditions most often present when smoke toxicity is the cause of death. It begins with a review of the evidence that smoke‐inhalation deaths are in the majority in fire fatalities in the United States. Next, there is an analysis of the evidence from the national fire experience showing the connection between post‐flashover fires and smoke‐inhalation deaths. Third is a presentation of real‐scale fire test results demonstrating that post‐flashover conditions are necessary to produce enough smoke to cause smoke‐inhalation deaths in the cases where they actually occur. The fourth component is a sampling of results from computer simulations of fires, affirming and broadening the results from the fire tests. It is concluded that smoke‐inhalation deaths occur predominantly after fires have progressed beyond flashover. This conclusion then provides a focus for smoke toxicity measurement in particular and fire hazard mitigation in general.
Correlation between cone calorimeter data and time to flashover in the room fire test
Authors: Östman Birgit A.‐L. , Tsantaridis Lazaros D. 
Published: December 2004

AbstractCorrelations based on linear regressions between data as time to ignition and heat release in the cone calorimeter and time to flashover in the room fire test have been developed. They are a further development of an earlier approach which has been modified and extended to a wider range of surface linings. The correlations apply so far only to surface linings on both walls and ceilings. When the density of the linings as a simplified measure of the thermal inertia is included, the correlations are improved significantly.The new correlations are based on data readily available from the cone calorimeter test at one heat flux level, 50 kWm−2. The correlation coefficient for the basic relationship, including the density of the linings, is now 0.98 when applied to the 13 linings investigated earlier. This is slightly better than the previous study, in which the best correlation coefficient was 0.96. When applied to 28 linings, the correlation coefficient remains about the same (0.97).Very similar regression equations have been obtained when analysing only 13 products and all 28. This is a strong indication of the general predictive capacity of this approach. The inclusion of other data such as thickness of linings or mass loss during fire does not improve the correlation coefficients. The approach is quite straightforward and simple. However, it has provided a useful prediction which is also valid for an extended range of linings.
Reduced combustion efficiency of chlorinated compounds, resulting in higher yields of carbon monoxide
Authors: Schnipper Anette , Smith‐hansen Lene , Thomsen Erling Sonnich 
Published: December 2004

AbstractA series of experiments involving the combustion of inherently fire‐retarded compounds has been performed using the DIN 53 436 furnace. Six chlorinated compounds comprising four pesticides, an organic solvent, and polyvinyl chloride (PVC) have been investigated with the focus on the combustion efficiency expressed as the CO2/CO ratio in the fire effluent. It was found that increased chloride content in a compound resulted in decreased CO2/CO ratio. The correlation was found to be \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {{\rm CO}_{\rm 2} /{\rm CO}} = 0.61 \times ({\rm Cl/C)}^{- {\rm 1}} + 0.13 $\end{document}. The results indicate higher concentrations of CO in the fire effluent from chlorinated compounds than from wood. Together with a release of HCI this could result in an increased toxic potency. The overall toxic hazard may or may not be increased, since (inherently) fire‐retarded materials tend to have an improved fire performance.
Fire‐retardant performance of some surface coatings for naval ship interior applications
Authors: Brown J. R. , Mathys Z. , Riddell S. Z. , Wake L. V. 
Published: December 2004

AbstractThe fire‐retardant performances of various surface coatings for naval ship interior applications have been evaluated by a number of small‐scale fire test methods. The coatings were eveluated as topcoats by cone calorimetry and limiting oxygen index methods and as primer/topcoat systems by radiat heating, direct flame impingement and reverse panel heating procedures. The coatings investigated were (1) a solvent‐based epoxy polyester, (2) a solvent‐based fireretardant alkyd,(3) a solvent‐based chlorimated alkyd and (4) a water‐based acrylic. In terms of the measured parameters, the chlorinated alkyd has superior fire properties while the epoxy polyserter, the fire‐retardant alkyd and parameters, the chlorinated alkyd has superior fire properties while the epoxy polyester, the fire‐retardant alkyd and the acrylic have significat disadvantages in relation to fire propagation. The relatively low amount of hydrogen chloride (∼ 0.3%—mass per initial mass) evolved by the chlorinated alkyd during cone calorimetric combustion and its outstanding fire‐retardant properties have resulted in it being considered acceptable for naval ship interior applications.
Use of the ARGOS fire risk analysis model for studying chinese restaurant fires
Authors: Chow W. K. 
Published: December 2004

AbstractThe fire risk in Chinese restaurants in Hong Kong is analyzed using the ARGOS fire risk analysis model developed at the Danish Institute of Fire Technology. A sample size of fifteen Chinese restaurants with different floor areas and fire load densities is considered. Fire simulations are performed for two cases by assuming a PU foam furniture fire occurring in the dining hall and a kerosene fire in the kitchen. Correlations are derived between the floor area and the predicted maximum hot gas temperature, the corresponding smoke layer interface height and the cost of damaged stock in the restaurants. The effectiveness of fire protection systems including sprinkler systems and smoke vents in controlling the fire is also discussed.
Essential oil composition of Hypericum richeri Vill. from Italy
Authors: Ferretti G. , Maggi F. , Tirillini B. 
Published: December 2004

AbstractThe essential oil composition of aerial parts of Hypericum richeri Vill. from Italy was analysed by GC and GC–MS. Fifty‐one components of the essential oil were identiﬁed, representing 98.5% of the oil. The most abundant components were (Z)‐β‐ocimene (19.5%), n‐nonane (13.8%), β‐bisabolene (8.7%), and (E)‐β‐ocimene (8.0%). Copyright © 2004 John Wiley & Sons, Ltd.
Genomic organization of variant surface glycoprotein genes in Trypanosoma brucei procyclic culture forms
Authors: Parsons Marilyn , Nelson Richard G. , Stuart Kenneth , Agabian Nina 
Published: December 2004

AbstractThe production of the variant surface glycoprotein coat of bloodstream form African trypanosomes ceases after conversion to the procyclic form. In the bloodstream stage alternate expression of different variant surface glycoprotein genes is responsible for the antigenic variation that occurs during relapse infections in the mammalian host. We have examined procyclic stage populations, derived from different bloodstream variant antigen types, for the two types of genomic alterations associated with variant surface glycoprotein genes in the bloodstream stage. Transcriptional activation of some variant antigen genes is accompanied by the generation of a new copy of the gene, the expression‐linked copy. We find that the expression‐linked copy is maintained after conversion to procyclic form, indicating that the presence of an expression‐linked copy is not sufficient for the expression of a surface coat. Sequences 3′ to other variant surface glycoprotein genes show expression‐independent variation in bloodstream stage trypanosomes. The same genes showed variation between procyclic populations of different origin, and between procyclics and their bloodstream parent. These data are discussed in light of observations on the sequence of variant antigen expression after cyclic transmission.
Herbicide‐quinone competition in the acceptor complex of photosynthetic reaction centers from rhodopseudomonas sphaeroides: A bacterial model for PS‐II‐herbicide activity in plants
Authors: Stein Randall R. , Castellvi Alicia L. , Bogacz Jerome P. , Wraight Colin A. 
Published: December 2004

AbstractA select group of herbicides that inhibit photosystem II also act at the acceptor side of the reaction center (RC) from the photosynthetic bacterium Rhodopseudomonas sphaeroides, with much the same relative specificity as in plants. These include the triazines and some phenolic compounds. The proposal that herbicides inhibit the electron transfer from the primary quinone (QA) to the secondary quinone (QB) by competing for the secondary quinone binding site—the B‐site— [5], is tested here with terbutryn, the most potent of the triazines. Competition between terbutryn and ubiquinone (Q‐10) was observed using the kinetics of the back‐reaction as a measure of inhibition. The model includes binding equilibria before and after flash activation. The binding constants for the preflash (dark) equilibria, for reaction centers in 0.14% lauryl dimethylamine‐N‐oxide (LDAO), were K = 0.8 μM terbutryn, K = 2 μM Q‐10; both are detergent‐concentration dependent. After flash activation, binding equilibrium is not fully restored on the time scale of the back‐reaction because terbutryn unbinds slowly. This gives rise to biphasic decay kinetics from which koff for terbutryn was estimated to be 3 sec–1. Titrations of the rate of the slow back reaction indicated that the post‐flash equilibrium is less sensitive to inhibitor, in a manner that is independent of the much stronger binding of the semiquinone, Q, and indicative of a direct effect of the redox state of QA on the affinity of the B‐site for ligands. However, the effects on K and K could not be separated: either K > K or K < K. Some triazine‐resistant mutants have been isolated and are described. All appear to be herbicide binding site mutants. Whole cells and photosynthetic membrane vesicles (chromatophores) exhibit a 10–50‐fold increase in resistance to triazines due, in large part, to an increase in the rate of unbinding (koff). The modifications of the binding site appear to diminish the affinity of the B‐site for ubiquinone as well as terbutryn. It is concluded that bacterial RCs are a useful model for the study of herbicide activity and specificity.
Inhibition of erythrocyte membrane shape change by band 3 cytoplasmic fragment
Authors: Carter David P. , Fairbanks Grant 
Published: December 2004

AbstractThe ATP‐dependent transformation of crenated white human erythrocyte ghosts into smoothed disc and cup forms is inhibited by the soluble 40–45‐kilodalton (kDa) cytoplasmic portion of the major transmembrane protein, band 3. The band 3 fragment was prepared by chymotryptic treatment of inverted vesicles stripped of peripheral proteins. When present at ≥0.2 mg per mg membrane protein (ie, ≥2 mol fragment per mol endogenous band 3), the fragment significantly reduced the rate of shape change but did not alter the proportion of membranes that were ultimately converted into smoothed forms (>90%). The inhibitory activity of the fragment could not be attributed to contamination of the fragment preparation by actin or proteolytic enzymes. ATP‐independent shape transformation was not inhibited. The band 3 fragment may compete with endogenous, intact band 3 for an association with the spectrin‐actin network required for ATP‐dependent smoothing of crenated membranes.
A requirement for cholesterol and its structural features for a human macrophage‐like cell line
Authors: Esfahani Mojtaba , Scerbo Louis , Devlin Thomas M. 
Published: December 2004

AbstractThe lipid requirements of a human macrophagelike cell line were studied. The cells grew only about one generation in a medium supplemented with delipidated serum; during the growth the cholesterol content of the cells was depleted. Growth was restored by including in the medium serum lipids subjected to alkaline hydrolysis or cholesterol. The extent of growth was dependent on cholesterol concentration. No growth was obtained with 5‐cholestene, 5‐cholesten‐3‐one, cholesteryl chloride, coprostanol, β‐sitosterol, orstigmasterol. Very limited growth occurred with cholesterol methylether, epicholesterol, or β‐cholestarol. Therefore, for optimal growth of these cells there is a stringent requirement for the structural features of cholesterol, which include a 3‐βOH group, a Δ5 ‐double bond, a trans ring A/B configuration, and freedom of the side chain from bulky groups. This stringency far exceeds what was previously reported for other cells. Of the six sterols that failed to support growth at all, five were incorporated into cells moderately to extensively. This suggests that assembly of a functional membrane is impaired when these sterols are used as substrates for growth.
Kinetic analyses of the membrane‐bound alkaline phosphatase activity of hymenolepis diminuta (cestoda: Cyclophyllidea) in relation to development of the tapeworm in the definitive host
Authors: Pappas Peter W. 
Published: December 2004

AbstractThe specific activities of the alkaline phosphatase (APase), type I phosphodiesterase and 5′‐nucleotidase activities associated with the brush‐border plasma membrane of the tapeworm, Hymenolepis diminuta, decrease significantly as the tapeworm grows and matures. Kinetic analyses of the APase activity associated with membrane preparations from whole 6‐, 12‐, and 18‐d‐old H diminuta, and individual pieces of 18‐d‐old H diminuta cut into ten pieces of equal length, failed to demonstrate qualitative changes in the APase activity. Therefore, the decreased specific activities are apparently due to changes in the ratios of enzymatically active to enzymatically inactive membrane proteins (ie, quantitative changes in the membrane proteins) which occur as the tapeworm grows.
Initiation of proliferative events by human α‐thrombin requires both receptor binding and enzymic activity
Authors: Carney Darrell H. , Stiernberg Janet , Fenton John W. 
Published: December 2004

AbstractTo determine the role of thrombin high‐affinity receptor occupancy and enzymic activity in thrombin initiation of cell proliferation, we have utilized thrombin derivatives which separate these functions. We previously showed that enzymically active γ‐thrombin stimulates ion fluxes without binding to high‐affinity sites, whereas proteolytically inhibited DIP‐α‐thrombin which binds to high‐affinity receptors does not. Since neither derivative initiates DNA synthesis by itself, this suggested that two separate sequences of events might be necessary for a complete initiation signal. We now report that the combination of DIP‐α‐thrombin and γ‐thrombin initiate DNA synthesis and cell proliferation to levels approaching the maximal initiation by native α‐thrombin. This combinatory effect is dose‐dependent for both γ‐thrombin and DIP‐α‐thrombin in the same concentration range as α‐thrombin alone. Thus, these same concentrations of α‐thrombin alone may be required to initiate each sequence of events. The combinatory stimulation could be achieved even if the derivatives were added individually up to 8 hr apart. Moreover, preincubation with either derivative shortened the lag period for initiation of DNA synthesis by native α‐thrombin. These results indicate that both receptor occupancy and enzymic activity are necessary for thrombin initiation of cell proliferation and that each action initiates a sequence of early events which moves the cell forward toward entry into a proliferative cycle.
Acidification of endocytic compartments and the intracellular pathways of ligands and receptors
Authors: Yamashiro Darrell J. , Maxfield Frederick R. 
Published: December 2004

AbstractSeveral hormones, serum proteins, toxins, and viruses are brought into the cell by receptor‐mediated endocytosis. Initially, many of these molecules and particles are internalized into a common endocytic compartment via the clathrin‐coated pit pathway. Subsequently, the ligands and receptors are routed to several destinations, including lysosomes, the cytosol, or the plasma membrane. We have examined the mechanism by which sorting of internalized molecules occurs. A key step in the process is the rapid acidification of endocytic vesicles to a pH of 5.0–5.5 This acidification allows dissociation of several ligands from their receptors, the release of iron from transferring, and the penetration of diptheria toxin and some viral nucleocapsids into the cytoplasm. Transferrin, a ligand that cycles through the cell with its receptor, has been used as a marker for the recycling receptor pathway. We have found that in Chinese hamster ovary (CHO) cells transferrin is rapidly segregated from other ligands and is routed to a complex‐of small vesicles and/or tubules near the Golgi apparatus. The pH of the transferrin‐containing compartment is approximately 6.4, indicating that it is not in continuity with the more acidic endocytic vesicles which contain ligands destined to be degraded in lysosomes.
Modulation of type α transforming growth factor receptors by a phorbol ester tumor promoter
Authors: Davis Roger , Like Betsy , Massagué Joan 
Published: December 2004

AbstractEpidermal growth factor (EGF) and an EGF‐like transforming growth factor (eTGF) from retrovirally transformed cells bind to a common receptor type in A431 cells. We have investigated the effects of the tumor promoter phorbol myristate acetate [PMA] on EGF/eTGF receptors in intact A431 cells. Treatment with PMA at 37°C induces a complete loss of high‐affinity (Kd = 35–50 pM) binding sites for eTGF and EGF on the cell surface of A431 cells. This effect is half‐maximal at 0.1 nM PMA, exhibits rapid kinetics, and persists for at least 4 hr in the presence of PMA. eTGF and PMA added to intact A431 cells induce the phosphorylation of immunoprecipitable 170kd EGF /eTGF receptors. The EGF/ eTGF receptor isolated from control cells was found to contain phosphoserine and phosphothreonine. PMA and eTGF caused a marked increase in the level of these two phosphoamino acids. In addition, eTGF but not PMA caused the appearance of phosphotyrosine in the EGF/eTGF receptor in vivo. We conclude that the tumor‐promoting phorbol diester regulates both the affinity and phosphorylation state of the A431 cell receptor for the type α transforming growth factors, eTGF and EGF.