Quantitative visualization of temperature field in non-luminous flame by flame reaction technique

Abstract  

An experimental technique for measuring a temperature field in an axisymmetric non-luminous flame is developed using the flame reaction technique combined with the inverse Abel transformation. Flame visualization is carried out using alkali metal solution of Potassium (K), which is supplied to a premixed methane/air flame in a form of spray mist. The basic principle of this technique is based on the measurement of local emission intensity distribution visualized by the flame reaction, which is a function of temperature according to the Maxwell–Boltzmann statistics of thermodynamics. The relationship between the local intensity and the temperature is obtained from the calibration study, in which the local intensity is evaluated from the line of sight intensity by the inverse Abel transformation, and the temperature is measured by thermocouple. This technique is successfully applied to the measurement of local temperature distribution in steady and flickering premixed methane/air flame. The temperature field in the flickering flame indicates that the local temperature oscillates periodically with the flickering frequency, and the highest temperature is found along the flame front and in the merging region.     

Large four-wave mixing of spatially extended excitonic states in thin GaAs layers

We study the size dependence of the nonlinear response of weakly confined excitons for the size region beyond the long wavelength approximation regime. The observed degenerate-four-wave mixing signal of GaAs thin layers exhibits an anomalous size dependence, where the signal is resonantly enhanced at a particular thickness region. The theoretical analysis elucidates that this enhancement is due to the size-resonant enhancement of the internal field with a spatial structure relevant to the nondipole-type excitonic state. These results establish the formerly proposed new type of size dependence of nonlinear response due to the nonlocality induced double resonance.     

Synthesis and molecular geometry of an achiral 30-crown-12 polyacetal from alpha-cyclodextrin

Periodate oxidation of alpha-cyclodextrin followed by borohydride reduction readily provided an octadeca-hydroxymethyl-substituted 30-crown-12 polyacetal 1, its 30-membered macrocycle being composed of six meso-butanetetrol/glycolaldehyde acetal units, which is, consequently, optically inactive. Its solid-state molecular geometry emerged from the X-ray structural analysis of the well-crystallizing octadeca-acetate 2, which revealed the undulated macrocycle to be molded into three loops with a unique order of succession of the -CHR-CHR-O-CHR-O- units: alternating gauche- and anti-conformations of the meso-butanetetrol portions and consecutive disposition of the glycolaldehyde-acetoxymethyl groups above and below the mean-plane of the macrocycle. In solution, however, as evidenced by 1H- and 13C-NMR spectra, the macrocycle is highly flexible at ambient and higher temperatures, its mobility becoming distinctly restricted only below -20 degrees C.     

Sorption and diffusion of water vapor in polyimide films

Sorption and diffusion of water vapor are investigated gravimetrically for polyimide films. The activity dependence of the solubility and diffusion coefficients, S and D, respectively, is classified under four types: (1) constant S and D type, (2) dual-mode sorption and transport type, (3) dual-mode type followed by a deviation due to a plasticization effect at high vapor activity, and (4) constant S and D type followed by a deviation due to water cluster formation at high activity. For the dual-mode type, the Henry's law component is much larger than the Langmuir component except at low activity, and therefore deviation in behavior from the first type is small. S is larger for polyimides with higher content of polar groups such as carbonyl, carboxyl, and sulfonyl. D is larger for polyimides with a higher fraction of free space, with some exceptions. The polyimide from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and dimethyl-3,7-diaminodibenzothiophene-5, 5-dioxide belongs to the third type and displays both large S and large D. The polyimide from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride and 4,4′-oxydianiline belongs to the fourth type, and has the largest D but rather small S because of the hydrophobic C(CF₃)₂ groups. © 1992 John Wiley & Sons, Inc.     

Ferroelectric liquid crystalline phase transition of (S)-hexakis(4-(4'-(6-methyl)octyloxy)biphenoxy) cyclotriphosphazene

(S)-Hexakis(4-(4'-(6-methyl)octyloxy)biphenoxy)cyclotriphosphazene (SMOCP) was synthesized in a search for new ferroelectric liquid crystalline compounds. We found an enantiotropic ferroelectric smectic C* phase between 419 and 441 K in SMOCP by using polarizing microscopy and DSC measurements. The spontaneous polarization was estimated to be -130.5 μCm^-2 at 437.6 K, several times larger than that of DOBAMBC ((S)-2-methylbutyl 4-(4'-decyloxybenzylidene)aminocinnamate.     

Dissociation between lactate accumulation and acidosis in middle cerebral artery-occluded rats assessed by P and H NMR metabolic images under A 2-T magnetic field

The relationships among tissue edema, lactate accumulation, and intracellular pH in middle cerebral artery (MCA)-occluded rats were investigated with multiecho ¹H magnetic resonance imaging and spatially resolved metabolic images constructed by ¹H and ³¹P nuclear magnetic resonance (NMR) chemical shift imaging (CSI). For the effective and sensitive detection of NMR signals from the brain, outer volume suppression (OVS), reduced k-space sampling and proton irradiation were incorporated into the CSI sequences. The consecutive three measurements of calculated T₂ image, lactate image, and pH image which were required for 3.75 h were repeated for four cycles of 1–16 h after MCA occlusion. Tissue edema and lactate accumulation in the infarcted region were gradually and consistently increased during the 15-h observation period. In contrast, severe acidosis was already detected on the first pH image (2–4.7 h after MCA occlusion); thereafter, the degree of acidosis became milder and showed no further progression. The dissociation between the time courses of the lactate accumulation and pH decrease was clearly demonstrated by the NMR metabolic images. Acid-base balance in cerebral infarction might be affected not only by lactate production but also by complicated interactions with tissue edema and some other factors.     

Synthesis and properties of noncyclic polyether compounds. Part V : The influence of acid and concentration of cations on the uphill transport rates of cations and selectivities through liquid membranes by synthetic,noncyclic polyether ionophores

The effects of acid and cation concentration on the uphill transport rates of cations and selectivities through chloroform liquid membrane by noncyclic polyether ionophores, which are pentaethylene glycol derivatives containing both 8-quinolyt and o-carboxylphenyl terminal groups, have been demonstrated. Using sulfuric, oxalic, or polyphosphoric acid in aqueous solution, the initial transport rates and the amount of cation transported by the ionophores after two days were larger than those using hydrochloric or nitric acid. Using picric acid, the amount of cation transported decreased greatly. It was confirmed that it decreased where an acid could easily be counter-transported by the ionophore through liquid membranes. On the other hand, it was found that the rates, amounts of cation transported, and selectivities, change with the changing of the cation concentration in the aqueous solutions. When the cation concentration in both aqueous solutions is high enough compared with the pH gradient between the two aqueous solutions, the rate, amount, and selectivity of the ionophore for potassium ion increases compared with when the cation concentration is low.     

A naphtho-tri-t-butyltrisdehydro[16]annulene and related compounds

Synthesis of naphtho-tri-t-butyltrisdehydro[16]annulene containing a hexapentaene and an acetylene units has been described. It was found that the [16]annulene is less stable and the paratropicity is much stronger as compared with previously reported isomeric naphtho[16]-annulene containing a diacetylene and a butatriene linkage.