Shorter Induction Time Research Articles

New ignition phenomenon in coal combustion

A reducing-to-oxidizing (RO) environment is characteristic of what a coal particle experiences in the near-burner region of pulverized coal (pc) furnaces. The RO environment can influence early-stage coal combustion processes such as ignition, aerosol formation, and char burnout. However, fundamental studies have focused on either oxidizing conditions (mimicking the post-flame region) or reducing conditions (mimicking the devolatilization region). The effect of this RO environment on early-stage coal combustion has, until now, not been considered. Here, the role of this reducing-to-oxidizing environment on single-particle ignition is evaluated. Powder River Basin (PRB) sub-bituminous coal was used, with a particle size of 125–149 μm and two nominal gas temperatures of 1300 K and 1800 K. The experimental findings for purely-oxidizing conditions with 20 vol% oxygen are compared with those of reducing-to-oxidizing environment. Single particles were tracked using high speed, high resolution videography. Emission intensities of the particles were used to evaluate the prevailing ignition modes, and to determine the characteristic ignition and induction times in both oxidizing and reducing-to-oxidizing environments. Experimental findings show that homogeneous-to-heterogeneous mode of ignition is prevalent for purely oxidizing conditions for both nominal gas temperatures of 1300 K and 1800 K. However, hetero-homogeneous ignition is favored in reducing-to-oxidizing environment at 1800 K and heterogeneous ignition at 1300 K gas flame temperature. The reducing-to-oxidizing environment leads to longer ignition delay times of about 20% and 40% on average for 1300 K and 1800 K nominal gas temperatures respectively but shorter induction times than those of oxidizing condition. The results show that ignition behavior in a reducing-to-oxidizing post-flame environments can be quite different from those in oxidizing environments.

Embryogénèse somatique directe à partir de cultures d'anthères du Cichorium (Asteraceae)

Somatic embryoids and diploid plants have been obtained directly from anther cultures of an hybrid Cichorium intybus L. × Cichorium endivia L. maintained by micropropagation. Anthers at tetrad and microspore stages were the most reactive. Darkness and high temperature (35 °C) were necessary to obtain somatic embryo development on a medium with naphthylacetic acid (0.02 mg ∙ L−1) and 6-(dimethylallylamino)-purine (0.5 mg ∙ L−1). A combination of glutamine and ammonium nitrate was the most suitable nitrogen source. A short induction time (10 days) allowed the embryoids to grow into adult plants. Most plants from the somaclonal population derived from these embryoids showed a good phenotypic conformity, and some variants showed a large anthocyanic vein or narrow and incised leaves. Key words: somatic embryos, anthers, Cichorium, in vitro culture.

Histological, physiological and genetical studies of the responses of leaves and pods of Phaseolus vulgaris to three races of Pseudomonas syringae pv. phaseolicola and to Pseudomonas syringae pv. coronafaciens

The responses of bean leaves and pods to races 1, 2 and 3 of Pseudomonas syringae pv. phaseolicola and to P.s. pv. coronafaciens were compared. Compatible and incompatible reactions were more clearly distinguished in pods than in leaves. Ultrastructural studies showed that a prolonged biotrophic phase of infection occurred in susceptible pods. Colonies of avirulent and virulent bacteria were surrounded by acidic polysaccharides in the intercellular spaces, A rapid hypersensitive reaction (HR) occurred in tissues of Phaseolus vulgaris cv. Tendergreen inoculated with race 3 or P.s. pv. coronafaciens. The intensity of the reaction was indicated by the low numbers of bacteria required for symptom development, shorter induction times than for race 1 in P. vulgaris cv. Red Mexican and higher concentrations of phaseollin recovered from cv. Tendergreen than other cultivars Experiments with mixed inocula suggested that production of elicitors of the HR rather than suppression of the resistant reaction by virulent isolates occurred. No evidence was obtained for the release of diffusible elicitors of the HR from avirulent bacteria or from responding tissue. Mutants of race 3 with altered virulence were recovered following treatment with nitrosoguanidine causing c. 7% of survivors to be auxotrophs. Three categories of mutants were recovered after screening on pods of cultivars Canadian Wonder, Red Mexican and Tendergreen (1) mutants with altered varietal specificity, they had lost the ability to cause the HR in cv. Tendergreen but caused large watersoaked lesions in all cultivars tested, (2) forms which caused small watersoaked lesions in the susceptible cultivars, Canadian Wonder and Red Mexican, but caused the HR in cv. Tendergreen, and (3) non-pathogenic forms failing to cause symptoms in any cultivar.

Diffuse interface between polymers: Structure and kinetics

AbstractThe interfacial structure and diffusion kinetics of two compatible polymers, poly(methyl methacrylate) and poly(vinylidene fluoride) are studied in the melt. The interdiffusion rates of the two components are found to be unequal, giving unequal diffusion coefficients, a net mass flow across the interface, and an asymmetric interfacial composition profile. The structure and kinetics confirm the predictions of the reptation theory. The interfacial thickness d grows with t1/2, and the interdiffusion coefficient is proportional to M−2, where t is the time and M is the molecular weight. The scaling law for the interfacial thickness is therefore d ∝ M−1t1/2. The number of chains per unit area crossing the original interface reaches a constant value independent of diffusion time after a short induction time on the order of the tube disengagement time (about 0.1–10 s in the present cases depending on the molecular weights). The adhesive bond strength σ is scaled by σ ∝ t1/4M−1/2 and σ/σ∞ ∝ t1/4M−1/2 [1‐ (Mc/M)]−1, where σ ∞is the σ at infinite molecular weight and Mc is the entanglement molecular weight.

Surface analysis of methylchlorosilane formation catalysts

The surfaces of Cu 3Si and Cu 3Si containing 0.4 at.% Zn (Cu 3SiZn) were analyzed with Auger spectroscopy, as a function of reaction temperature, before and after reaction with atmospheric-pressure CH 3Cl. These surfaces, which selectively form (CH 3) 2SiCl 2, contained silicon, copper, chlorine, carbon, and a small amount of oxygen after reaction. The Cu 3SiZn surface also contained zinc. The Si(LVV) Auger transition exhibited chemical shifts which indicated the presence of SiCl, SiC, and SiCu bonds. Active sites for selective (CH 3) 2SiCl 2 formation appear to contain silicon bound to chlorine. Copper weakens silicon bonds in the alloy, and this may result in faster SiCl bond formation and shorter induction times than for the uncatalyzed reaction. Silicon carbide sites, which do not contain chloride, are also present after reaction, but apparently do not form silanes. The Cu 3Si and Cu 3SiZn surfaces differ dramatically after reaction. The fraction of surface silicon which formed silicon carbide sites was smaller for Cu 3SiZn than for Cu 3Si; however, the Cu 3SiZn surface contained up to 85% graphitic carbon though no graphite was detected on Cu 3Si. Zinc may promote conversion of carbide to graphitic carbon. Graphite did not significantly affect silane formation kinetics, however, suggesting that only a fraction of the surface was active for silane formation.

The influence of age on the onset of anaesthesia with midazolam.

There was a considerable individual variation in response to a standard induction dose of 0.3 mg/kg midazolam in unpremedicated patients. This is shown by variations in time to onset of sleep and the fact that about one quarter of subjects did not lose consciousness in 3 minutes. In 166 fit patients a good negative correlation was demonstrated between the age of the patients and time to loss of consciousness. Patients over 50 years differed from younger patients in a greater reliability of effect and significantly shorter induction time. In elderly patients midazolam is a more reliable induction agent than in the young.

The proportions of hemoglobin types induced in mouse erythroleukemia cells vary with the inducer or combination of inducers, the inducer concentration and the time of induction.

The relative amounts of hemoglobin (Hb) major and Hb minor accumulated during induction of erythrodifferentiation in mouse erythroleukemia (MEL) cells were studied. The ratio of major to minor was found to depend not only upon the inducer tested (as reported previously by others), but also upon the concentration of the inducer and the time of exposure to the inducer as well as the specific cell line of MEL cells studied. At concentrations required for optimal induction of differentiation, certain agents led to the accumulation of predominantly Hb major, but suboptimal concentrations of the same inducers led to predominantly Hb minor accumulation. After a relatively short induction time (2 da) utilizing a given inducer either the level of Hb minor was higher than that of Hb major or the levels of the two Hb's were approximately equal, but after longer induction periods (3-7 da) Hb major was more abundant than Hb minor. In addition, it was found that the three proteases tested induced predominantly Hb minor. The addition of suboptimal concentrations of low molecular weight inducers acted synergistically with a given protease to produce a high yield of Hb-containing cells. When these agents were added singly they induced relatively low Hb major/Hb minor ratios, but when a low molecular weight inducer was added together with a protease in a "synergistic" combination, elevated ratios were induced. The proportions of hemoglobin types induced in MEL cells may be related in part to the intensity of the induction response. In view of these data, classifications of inducers based solely on the ratios of Hb types produced must be guarded.

The Effect of Selective Energy Deposition on the Homogeneous Ignition of Methane and its Implication for Flame Initiation and Combustion Enhancement

Abstract This paper describes a computational study of the ignition of methane mixtures by selective ignition energy deposition. In this work the ignition energy was added as an initial condition to the combustible mixture in a specific manner, either in the form of heat or a combination of heat and selected, highly reactive atoms or molecules. The resulting induction time for the ignition of homogeneous combustion was found to decrease with increasing fraction of ignition energy deposited into dissociation for the same total ignition energy at a given equivalence ratio. In addition to these calculations performed at constant energy, other calculations were performed where equal amounts of the radicals H, O, and OH were added to assess the effect of direct addition of these radicals on the induction time. Oxygen atoms yielded the shortest induction time in the stoichiometric case and hydrogen atoms yielded the shortest induction time in the lean case. Hydroxyl radicals yielded by far the longest induction...

Induction Time Studies of Fe18Cr and 430 SS under Open Circuit Conditions in Chloride-Containing Sulfuric Acid

Abstract In order to promote the effective and efficient application of corrosion resistant metals and alloys in mineral processing environments, the Bureau of Mines, U.S. Department of the Interior, has characterized the effect of aggressive ions on the corrosion and passive behavior of two stainless steels, Fe18Cr and AISI 430 SS. Samples prepassivated in oxygen saturated 1 N H2SO4 at 0.6 V NHE and then released to open circuit and aged for times ranging from 10 min to 80,000 min (55 days), were subsequently exposed to chloride ion concentrations ranging from 5 to 44 parts per thousand (ppt). Susceptibility to chloride ion attack was determined as a function of time in solution (film aging time), chloride ion concentration [Cl−], and open circuit potentials (E) at the time chloride was added by measuring the amount of time (induction time, t) required for a sample to begin corroding after adding the chloride ion. The experimentally determined induction times were fitted to an equation of the form: 1/t=K Em[Cl−]n where K, m, and n are empirically determined constants. Results obtained for short (<100 min) aging times were different from those for long (100 to 80,000 min) aging times. For Fe18Cr exposed for short film aging times prior to addition of the chloride, larger [Cl−] resulted in shorter induction times, and higher values of E resulted in longer induction times. For 430 SS exposed for short film aging times, and for 430 SS and Fe18Cr exposed for longer film aging times prior to addition of chloride ions, both larger [Cl−] and higher values of E resulted in shorter induction times.

MIDAZOLAM: a shorter induction time than thiopentone

MIDAZOLAM: a shorter induction time than thiopentone

Observations of fouling biofilm formation.

Fouling biofilm development was monitored in a completely mixed tubular recycle reactor. A unique sampling system allowed direct (brightfield, epifluorescence, and scanning electron photomicroscopy) and indirect (increased fluid frictional resistance) observations of biofilms. Low fluid velocity (138.5 cm/s) experiments had shorter induction times and biofilm matrixes which included firmly adherent filamentous bacteria. High fluid velocity (265.4 cm/s) experiments had longer induction times with firmly adherent filamentous bacteria present only after the accumulation of extracellular materials. In both cases the fluid frictional resistance increased after filamentous bacteria became a permanent part of the biofilm.

A shock-tube study on the process of soot formation from acetylene pyrolysis

The induction times for soot formation were measured for several mixtures of acetylene behind reflected shock waves over a wide temperature range (1500 to 3300 K) and it was found that there were three temperature ranges showing different trends of the induction time with temperature. Besides pure acetylene, mixtures containing a small amount of oxygen or water vapor were also used to elucidate the effects of combustion product species, and OH was found to be the species most likely to suppress soot formation. The carbon mass growth rates were also measured for these mixtures, and it was found that a large carbon mass growth rate corresponded to a short induction time.

Effect of Anesthetic Agent on Lung Tumor Induction in Hamsters Given Benzo[a]pyrene-Ferric Oxide2

The effects of an anesthetic agent on lung tumor induction in noninbred Syrian golden hamsters were investigated after intratracheal instillation of a benzo[a]pyrene-ferric oxide mixture. Inhalation anesthesia with ether or methoxyflurane was accomplished with a closed recirculatory system that allowed a short induction time for anesthesia and a good control over the concentration of anesthetic. This type of anesthetic induction was compared with systemic induction by Brevital. Survival rates during the 10 weekly instillations were least for the Brevital-treated group and greatest for the methoxyflurane-treated group. Body weight gain was lower in both the ether- and Brevital-treated groups as compared to the group anesthetized with methoxyflurane. The animals anesthetized with Brevital had the shortest tumor latency, but the tumor incidence during the weeks of the experiment was similar in the group treated with this agent and the group treated with ether. Exposure to methoxyflurane and the carcinogen produced a slow onset of deaths from tumors and lower tumor incidence. These results are discussed in relation to retention of the dose of carcinogen in the respiratory tract and effect of inhalation anesthia on consequent lung tissue pathology.

Effect of shear on the crystallization kinetics of poly(ethylene oxide) and poly(e‐caprolactone) melts

AbstractThe effect of shear on polymer crystallization kinetics has been studied for three materials at several shear rates and degrees of supercooling. Two poly(ethylene oxide) samples, with molecular weights of 72, 200 and 12, 600, and a poly(e‐caprolactone) material, with a molecular weight of 9, 400, were investigated. The apparatus used was a concentric cylinder viscometer, which also functions as a dilatometer, capable of detecting very small volume changes on crystallization. The shear‐rate range of the experiments was 0 to 60 sec−1. Avrami kinetics were used to describe the transformation process and the exponent was found to increase from the quiescent value of 3 to a value greater than 5 with increasing shear rate for all materials studied. The acceleration in the transformation process was associated with a reduction in induction time. The value of induction time at high shear rates did not significantly decrease with increasing shear rate, indicating a saturation effect with shear. This was most pronounced in the low molecular weight samples. The value of induction time for the high molecular weight poly(ethylene oxide) sample, under identical experimental conditions, was substantially less than that of the low molecular weight material in all cases. Nuclei formation measurements were made for the crystallizing melt in a separate instrument. Nuclei formation under shear was very different from quiescent behavior and increased substantially with increasing shear rate. These experimental observations lead to the conclusion that accelerated crystallization is due to increased molecular chain extension and orientation under shear. This orientation greatly enhances the nucleation process, which is thought to be the rate controlling step in the crystalline transformation. This enhancement results in shorter induction times and more rapid crystallization.

ChemInform Abstract: ROLE OF STRUCTURAL IMPERFECTIONS IN THE DECOMPOSITION OF DIBENZOYL PEROXIDE

Chemischer InformationsdienstVolume 6, Issue 43 Preparative Organic Chemistry ChemInform Abstract: ROLE OF STRUCTURAL IMPERFECTIONS IN THE DECOMPOSITION OF DIBENZOYL PEROXIDE SALAH E. MORSI, SALAH E. MORSISearch for more papers by this authorJOHN M. THOMAS, JOHN M. THOMASSearch for more papers by this authorJOHN O. WILLIAMS, JOHN O. WILLIAMSSearch for more papers by this author SALAH E. MORSI, SALAH E. MORSISearch for more papers by this authorJOHN M. THOMAS, JOHN M. THOMASSearch for more papers by this authorJOHN O. WILLIAMS, JOHN O. WILLIAMSSearch for more papers by this author First published: October 28, 1975 https://doi.org/10.1002/chin.197543115AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume6, Issue43October 28, 1975 RelatedInformation

Crystallization of polyethylene oxide under shear

AbstractA concentric cyclinder dilatometer was designed and built to study the influence of shear on the crystallization kinetics of polymers. This instrument allows crystallization to be followed at both constant temperature and shear rate. Several samples of polyethylene oxide (Carbowax 4000, Carbowax 20‐M, and WSR‐205) were used. A low molecular weight fraction of the Carbowax 20‐M, as well as the unfractionated material, was crystallized under shear. The WSR‐205 was studied only in a mixture with Carbowax 4000. It was shown that the kinetics of crystallization of uncrosslinked melts of polyethylene oxide are altered by shear. The induction times for the appearance of crystallinity are shorter in the sheared systems than in the quiescent melts. The Avrami exponents are also higher for crystallization in sheared melts than in quiescent systems and increase with decreasing supercooling. The high values of the Avrami exponent are attributed to the disruption of crystalline aggregates into particles larger than the critical sized nucleus. These particles will persist in the melt and continue to grow spontaneously. A continuous infusion of growing particles into the melt occurs.At constant temperature and shear rate, the induction time of the crystallization curve is influenced by polymer molecular weight. In moderate to high molecular weight samples, the effect of shear becomes saturated at very low shear rates. Decreasing the molecular weight separates the crystallization curves. The curves from the higher shear rates appear at the shorter induction times. However, decreasing the molecular weight below that at the critical entanglement molecular weight allows the nucleation rate, strongly dependent upon the supercooling, to influence the relative positions of the sheared crystallization curves.

Brain tumor types induced by the Schmidt-Ruppin strain of Rous sarcoma virus in inbred Fischer rats.

The Schmidt-Ruppin strain of Rous sarcoma virus has been shown to induce neuroectodermal and mesenchymal tumors of the brain of inbred CDF Fischer rats. The inoculation of 105 FFU of virus into the cerebrum of 2 day old rats was followed by 96% incidence of tumor growth after a latency period of 3 months. Twenty-four of twenty-five inoculated animals developed tumors, all of which were primary intracerebral neoplasms. They fell into three main groups: gliomas 60%, sarcomas 31%, gliosarcomas 9%. Of the 34 gliomas induced, 28 (84%) were astrocytic, and there was one oligodendroglioma, 2 mixed gliomas, and 3 ependymoma-like tumors. The advantages of this brain tumor model are a high glioma incidence, and a short induction time in a commercially available strain of inbred Fischer rats previously shown to be susceptible to the neuro-oncogenic action of resorptive chemical carcinogens.

The early stages of isotactic polypropylene oxidation

AbstractThe initial stages of isotactic polypropylene oxidation were investigated by oxidizing at 130°C. to various extents up to 10 ml. of oxygen consumed per gram of polymer. The development of infrared absorption bands in the carbonyl regions was followed, as increasing amounts of oxidation occurred. The oxidation uptake curves showed that both autocatalytic rate and induction time depended primarily on the thickness of the sample, contrary to the case of polyethylene. This indicated the initiation process was primarily diffusion controlled for samples of the thickness range studied. The presence of copper shortened the induction times and increased the autocatalytic rate. In this case, the dependency of the induction time on thickness was less. Dielectric data showed that polypropylene became unsuitable electrically at about the point where the autocatalytic oxidation set in. It was also found that the effects of prior exposure to oxidative conditions were cumulative to a considerable extent, and thus resulted in shorter induction times.

Providing a steady state for cardiac catheterization under anesthesia.

Data obtained by cardiac catheterization are especially difficult to interpret if the anesthesia and oxygenation are irregular. A relatively constant level of anesthesia and oxygenation can be maintained by using trichloroethylene. It is a nonflammable liquid that can be given with air by inhalation. It is safe to use in the presence of x-ray equipment. It was used, together with pentobarbital sodium or chloral hydrate, scopolamine, and meperidine, in 78 patients undergoing angiocardiography and 225 patients undergoing cardiac catheterization. All of the second group were under 16 years of age. The steadiness of the anesthetic state was measured by observations of the pulse and respiratory rate, ear oximeter readings, and determinations of femoral arterial oxygen saturation and of arterial carbon dioxide tension. The search should be continued for a drug with shorter induction time and less tendency to cause tachypnea and cardiac arrhythmia, but the technique using trichloroethylene satisfies most of the requirements of an ideal anesthetic technique and it did not seriously interfere with the determination of blood gases by conventional methods.

The combination of barbiturates with an emetic as a method for the prevention of suicide.

Summary.The combined administration of barbiturates and an emetic was investigated in cats as a possible method of preventing suicide by overdosage of sedatives.The locally acting zinc sulphate was used as an emetic together with phenobarbital and three barbiturate mixtures containing two components, one with a short induction time and duration of action, the other with intermediate ones.In sedative as well as in lethal doses, the barbiturates examined exerted an inhibitory effect on the vomiting produced by zinc sulphate.When emesis occurred, gastric emptying was not complete and there was no definite influence on the fatal effect of barbiturates. It was found in 40 per cent of the animals which died that the vomitus was aspirated into the bronchi with resulting signs of pneumonia.I am indebted to Pharmacia Ltd., Uppsala, for financial support of the investigation.