Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Octanes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2005

One-dimensional zinc-based coordination polymers incorporating cyanate anions.

Two one-dimensional zinc-based coordination polymers containing cyanate anions are reported. catena-Poly[sodium [[tricyanatozinc(II)]-mu-1,4-diazabicyclo[2.2.2]octane-kappa2N:N']], [Na[Zn(NCO)3(C6H12N2)]]n, consists of linear [tricyanatozinc(II)]-mu-1,4-diazabicyclo[2.2.2]octane strands in which the Zn2+ cations adopt trigonal-bipyramidal coordination on sites of -6m2 point symmetry. Na+ cations lie between the strands on sites of -3m point symmetry, coordinated in a distorted octahedral geometry by six O atoms of the cyanate anions. catena-Poly[[dicyanatozinc(II)]-mu-4,4'-bipyridine-kappa2N:N'], [Zn(NCO)2(C10H8N2)]n, crystallizes in the space group P2(1)/n with Z' = 5. The structure consists of zigzag strands formed by Zn2+ cations linked via 4,4'-bipyridine. Each Zn2+ cation adopts a tetrahedral coordination, with two sites occupied by 4,4'-bipyridine and two cyanate anions completing the coordination sphere. The structure is closely comparable with the thiocyanate and halide analogues [ZnX2(C10H8N2)] (X = NCS, Cl or Br).

Journal Article↗
PubMed2003

Salts of maleic and fumaric acids with organic polyamines: comparison of isomeric acids as building blocks in supramolecular chemistry.

Maleic acid and fumaric acid both readily form adducts with organic diamines: maleic acid usually forms 2:1 adducts with bases, while fumaric acid usually forms 1:1 adducts, and the supramolecular structures within the two series are not simply related. The 1:2 adducts formed by 1,2-bis(4-pyridyl)ethane and by 4,4'-bipyridyl, respectively, with maleic acid, compounds (1) and (2), are salts [(diamine)H(2)(2+)].[(C(4)H(3)O(4))(-)](2) in which the cations lie across a centre of inversion and a twofold rotation axis, respectively. The ions are linked by N-H...O hydrogen bonds into three-ion aggregates, which are further linked by C-H...O hydrogen bonds into two- and three-dimensional arrays, respectively. In the fumarate salts formed by 2,2'-dipyridylamine (1:1) and 1,4-diazabicyclo[2.2.2]octane (1:2), compounds (3) and (4), the ionic components are linked into molecular ladders. The 1:1 adduct of 4,4'-bipyridyl and fumaric acid, compound (5), contains two neutral components, both of which lie across centres of inversion; these components are linked into chains by a single O-H...N hydrogen bond and thence into sheets by C-H...O hydrogen bonds. The corresponding adduct formed by 1,4-diazabicyclo[2.2.2]octane, compound (6), is a salt that again contains chains linked into sheets by C-H...O hydrogen bonds. In the 1:1 adducts, compounds (7), (8) and (10), that are formed between 1,2-bis(4-pyridyl)ethane, 4,4'-trimethylenedipyridine and hexamethylenetetramine, respectively, with fumaric acid, and in the 1:2 adduct, compound (9), of 2,2'-dipyridylamine and maleic acid, the chains that are generated by the hard hydrogen bonds are linked by C-H...O hydrogen bonds to form, in each case, a single three-dimensional framework. In the 1:1 adduct, compound (11), of 2,2'-bipyridyl and fumaric acid the hydrogen bonds generate two interwoven three-dimensional frameworks.

Journal Article↗
PubMed1990

Kinetic theory of enzymatic reactions in reversed micellar systems. Application of the pseudophase approach for partitioning substrates.

A kinetic theory is proposed for enzymatic reactions proceeding in reversed micellar systems in organic solvents, and involving substrates capable of partitioning among all pseudophases of the micellar system i.e. aqueous cores of reversed micelles, micellar membranes and organic solvent. The theory permits determination of true (i.e. with reference to the aqueous phase, where solubilized enzyme is localized) catalytic parameters of the enzyme, provided partition coefficients of the substrate between different phases are known. The validity of the kinetic theory was verified by the example of oxidation of aliphatic alcohols catalyzed by horse liver alcohol dehydrogenase in the system of reversed sodium bis(2-ethylhexyl)sulfosuccinate (AOT, aerosol OT) micelles in octane. In order to determine partition coefficients of alcohols between phases of the micellar system, flow microcalorimetry technique was used. It was shown that in the first approximation, the partition coefficient of the substrate in a simple biphasic system consisting of water and corresponding organic solvent can be used as an estimate for the partition coefficient of the substrate between aqueous and organic solvent phases of the micellar system. True values of the Michaelis constant of alcohols in the micellar system, determined using suggested approach, are equal to those obtained in aqueous solution and differ from apparent values referred to the total volume of the system. The results clearly show that the previously reported shift in the substrate specificity of HLADH, observed on changing from aqueous solution to the system of reversed aerosol OT micelles in octane, is apparent and can be explained on the basis of partitioning effects of alcoholic substrates between phases of the micellar system.

Alcohol Dehydrogenase↗
PubMed1993

Enzyme inactivation and protection during entrapment in reversed micelles.

Lactate dehydrogenase (LDH) was found to lose rapidly its catalytic activity during the process of entrapment in hydrated reversed micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in octane. It was demonstrated that this inactivation was caused by the surfactant which penetrated into the injected enzyme-containing aqueous bulk phase during the short time of mechanical stirring needed to convert the initial biphasic mixture into a monophasic reversed micellar solution. The unfavorable inactivation phenomenon could be efficiently eliminated by the addition of either NADH or pyruvate into the enzyme stock solution prior to its injection into AOT solution in octane. The catalytic activity of substrate-protected LDH in AOT reversed micelles increased with increasing water content of the micellar system, reaching the maximal level above wo = 30 when aqueous inner cores of reversed micelles grew large enough to allow unrestricted accommodation of the enzyme molecule. It is suggested that the employment of substrate-protected enzymes could represent a generally useful approach for producing highly efficient enzyme-containing reversed micellar reaction systems.

Catalysis↗
PubMed1993

Fluorescent polyene aliphatics as spectroscopic and mechanistic probes for bacterial luciferase: evidence against carbonyl product from aldehyde as the primary excited species.

The fluorescent alpha-parinaric acid (alpha-PAC) and beta-parinaric acid (beta-PAC) were converted to the corresponding aldehydes and alcohols all of which exhibited absorption and fluorescence properties closely resembling those of the parent acids. alpha-PAC and beta-PAC each binds to luciferase in competition with aldehyde. The hydrophobic nature of the aldehyde site was indicated by the enhanced fluorescence quantum yields of the bound alpha-PAC and beta-PAC. These two polyene acids and the beta-parinaryl alcohol were shown to stabilize the luciferase flavin-peroxide intermediate. alpha-Parinaraldehyde (alpha-PAD) and beta-parainaraldehyde (beta-PAD) were active substrates for Vibrio harveyi and Vibrio fischeri luciferases and, for the former enzyme, exhibited Km values similar to and quantum yields about 20-30% as those for decanal and dodecanal. For the V. harveyi luciferase with reduced FMN as a co-substrate, the alpha-PAD- or beta-PAD-initiated luminescence was indistinguishable from the normal emission obtained with octanal (lambda max 495 nm) showing no additional 430-nm component correlatable with emission from excited alpha-PAC or beta-PAC. In reactions using reduced 2-thioFMN for V. harveyi luciferase or reduced FMN for V. fischeri luciferase plus yellow fluorescent protein, the replacement of octanal by beta-PAD again resulted in no additional 430-nm emission. The lack of any emission correlatable with excited alpha-PAC, beta-PAC, or equivalent carbonyl product was not due to the quenching of the polyene moiety by chemical transformation, binding to luciferase, or a 100% energy transfer to the flavin 4a-hydroxide emitter.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehydes↗
PubMed1980

Some effects of aliphatic hydrocarbons on the electrical capacity and ionic currents of the squid giant axon membrane.

1. The electrical properties of squid giant axons were examined by means of admittance bridges at frequencies from 0.5 to 300 kHz. A simple equivalent circuit was used to estimate the membrane capacity. 2. The calculated membrane capacities decreased monotonically over the whole frequency range. 3. At 100 kHz and higher frequencies the membrane capacity was independent of potential. 4. At frequencies greater than 20 kHz, exposure of the axons to saturated or 0.9 saturated solutions of n-pentane (275-306 micrometer) reduced the capacity per unit area by 0.1-0.15 micro F cm-2. 5. At 1 kHz the effect of the saturated pentane solutions depended on the membrane potential. In axons having potentials between -60 and zero mV the pentane solutions lowered the capacity, whereas for potentials between -160 and -60 mV they produced little or no change. 6. Saturated solutions of n-hexane, n-heptane and n-octane exhibited qualitatively similar, but quantitatively smaller influences on the membrane capacity, the changes declining as the chain length increased. 7. Under voltage clamp, the peak inward and steady-state outward currents were partially suppressed by the hydrocarbons. Saturated solutions of n-pentane usually reduced the former (reversibly) by 60-80% and the latter by 20-40%. Solutions of n-hexane, n-heptane and n-octane appeared to have successively less effect. Except in deteriorating axons, none of the hydrocarbons produced any consistent changes in the passive membrane resistance, the resting potential or in the reversal potential of the transient inward current. 8. Both the changes in the clamp currents and in the membrane capacity were largely, though not usually completely, reversible. In the hydrocarbon solution the axons deteriorated more rapidly than normal. 9. The responses of axons of Doryteuthis plei to the hydrocarbons were very similar to those of Loligo forbesi with the exception that for the former all observed changes were some five times faster. 10. The time courses of the peak inward and steady-state outward currents on exposure of the axons to n-pentane resembled the time course of the change in membrane capacity at 100 kHz. 11. The simplest interpretation of the high frequency capacity results is suggested to be that, as for lipid bilayers, the membranes become thicker through adsorption of the hydrocarbon.

Alkanes↗
PubMed1982

Nerve impulse blockage in squid axons by n-alkanes: the effect of axon diameter.

1. The anaesthetic effects of aqueous solutions of the n-alkanes pentane to nonane on the propagated action potential of squid axons have been investigated for a range of axon diameters. 2. By the use of small axons (approx. 200 microns diameter) to minimize effects due to long diffusion times and alkane depletion it was found that n-pentane and n-hexane caused a rapid reversible inhibition of the impulse, while higher homologues had progressively less effect, n-nonane being apparently inert. 3. The rate of action potential decline due to the n-alkanes was found to be strongly dependent on axon diameter. For n-hexane, n-heptane and n-octane the rate of decline was inversely proportional to the square of the axon diameter. 4. The mechanisms which may underly the increased sensitivity of small axons to impulse blockade by n-alkanes are discussed. A quantitative comparison is made between the effects of n-hexane, n-heptane and n-octane on the action potential. It is argued that this supports the idea of a real decline in anaesthetic potency on ascending the homologous series, rather than an effect due to long diffusion times and solution depletion.

Action Potentials↗
PubMedDate not supplied

On the application of a liquid-dielectric ionization chamber to 252 Cf dosimetry.

Our investigations of an iso-octane-filled liquid-dielectric ionization chamber indicate that this dosimeter is well suited for the measurement of dose distributions at distances close to 252Cf interstitial implant sources. Initial research has shown that such an instrument provides good discrimination between the radiation components of a mixed field and possesses excellent sensitivity. Calculations indicate that iso-octane will yield a neutron and gamma-ray dose response independent of energy over a major part of the 252Cf spectral range, while transmission measurements have demonstrated that the liquid causes little perturbation of the radiation field.

Californium↗
PubMed2006

Sesamin metabolites induce an endothelial nitric oxide-dependent vasorelaxation through their antioxidative property-independent mechanisms: possible involvement of the metabolites in the antihypertensive effect of sesamin.

Sesamin, a major lignan in sesame seeds and oil, has been known to lower blood pressure in several types of experimental hypertensive animals. A recent study demonstrated that sesamin metabolites had in vitro radical-scavenging activities. Thus, we determined whether the antioxidative effect of sesamin metabolites modulate the vascular tone and contribute to the in vivo antihypertensive effect of sesamin. We used four demethylated sesamin metabolites: SC-1m (piperitol), SC-1 (demethylpiperitol), SC-2m [(1R,2S,5R,6S)-6-(4-hydroxy-3-methoxyphenyl)-2-(3,4-dihydroxyphenyl)-3,7-dioxabicyclo[3,3,0]octane], and SC-2 [(1R,2S,5R, 6S)-2,6-bis(3,4-dihydroxyphenyl)-3,7-dioxabicyclo-[3,3,0]octane]. SC-1, SC-2m, and SC-2, but not SC-1m, exhibited potent radical-scavenging activities against the xanthine/xanthine oxidase-induced superoxide production. On the other hand, SC-1m, SC-1, and SC-2m produced endothelium-dependent vasorelaxation in phenylephrine-precontracted rat aortic rings, whereas SC-2 had no effect. The SC-1m- and SC-1-induced vasorelaxations were markedly attenuated by pretreatment with a nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine (NOARG), or a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one. Neither SC-1m nor SC-1 changed the expression level of endothelial NOS protein in aortic tissues. The antihypertensive effects of sesamin feeding were not observed in chronically NOARG-treated rats or in deoxycorticosterone acetate-salt-treated endothelial NOS-deficient mice. These findings suggest that the enhancement of endothelium-dependent vasorelaxation induced by sesamin metabolites is one of the important mechanisms of the in vivo antihypertensive effect of sesamin.

Animals↗
PubMed1980

Singlet oxygen and aging in Drosophila.

There was little or no improvement in the median survival times of Drosophila melanogaster fruit flies when fed high concentrations of the singlet oxygen quenchers, beta-carotene and 1,4-diazabicyclo(2.2.2)octane. Singlet oxygen was presumably generated endogenously by inactivating catalse with 3-amino-1,2,4-triazole and feeding NaOCl. This treatment caused reduction in median life span of from 14.3 to 25% depending upon the NaOCl concentration used. beta-Carotene and 1,4-diazabicyclo(2.2.2)octane gave partial protection against the singlet oxygen generated by NaOCl. These data are interpreted to mean that normally occurring singlet oxygen does not contribute to senescence in Drosophila but that artificially produced singlet oxygen accelerates the rate of aging.

Aging↗
PubMed1993

Perfluorocarbon effects on rabbit blood-retinal barrier permeability.

Studies have been made of the effects of intravitreal perfluoro-n-octane on the permeability to fluorescein of the blood-retinal barrier in rabbits. At day 1 after injection, there is increased aqueous humor fluorescence that reflects the physical disturbance to the eye following injection. From that time through 7 weeks, there is no evidence of any overt toxicity to the blood-retinal barrier. The retention in the vitreous of a small volume of perfluoro-n-octane following its intraoperative use would not be expected to induce a toxic response. Some effect on an already compromised retina cannot, however, be excluded.

Animals↗
PubMed2006

Analysis of the state and size of silver on alumina in effective removal of NOx from oxygen rich exhaust gas.

Ag/alumina catalysts with different silver contents for octane-SCR were prepared by impregnation and incipient wetness methods. Activity tests revealed that the decisive factor for high activity is not only a high dispersion of silver, but also the ability of the system to redisperse clustered silver. Determination of dispersion by TEM/HAADF and O2-chemisorption experiments resulted in values close to each other even if the results were not directly comparable. This is suggested to be due to not complete silver reduction below 700 degrees C and the samples being very heterogeneous in terms of particle size, e.g., having a bimodal size distribution. Small charged Agsigman+ clusters containing 2-8 silver atoms highly prevailed in the samples containing <2 wt% Ag and exhibiting high octane-SCR activity. In highly loaded Ag/alumina samples or those reduced and reoxidized at high temperature (>400 degrees C), large metallic particles are stabilized, resulting in poor conversion of NOx to N2.

Aluminum Oxide↗
PubMed2006

Fourier transform infrared study of lipoxygenase conformation in organic solvent media.

The secondary structure of commercially purified soybean lipoxygenase (EC 1.13.11.12) was investigated in selected monophasic organic solvents, including chloroform, methanol, acetonitrile, hexane, and octane. The Fourier transform infrared (FT-IR) spectra of the enzyme obtained in chloroform, methanol, and acetonitrile showed an absorption band at 1617 cm(-1) indicative of significant protein aggregation, whereas spectra of lipoxygenase in hexane and octane exhibited substantially less aggregate formation. Variable-temperature infrared studies of lipoxygenase in D(2)O show that the predominately alpha-helical structure of the protein undergoes an irreversible transition to intermolecular beta-sheet at and above 65 degrees C. Chemical imaging technology employing an FT-IR spectrometer equipped with an infrared microscope and a focal-plane array detector was used to examine the changes in the secondary structure of lipoxygenase at the water-hexane interface in the presence and absence of substrate. The secondary structure of lipoxygenase at the hexane-water interface was comparable to that of the structure of lipoxygenase in D(2)O after exposure of lipoxygenase solution to hexane.

Colloids↗
PubMedDate not supplied

Comparison of volatile compound production in fruit body and in mycelium of Pleurotus ostreatus identified by submerged and solid-state cultures.

Comparative analyses of the production of volatile compounds by Pleurotus ostreatus JMO.95 fruit body and its corresponding mycelium grown in liquid, on agar surface, and on solid support cultures were carried out by dynamic headspace concentration using gas chromatography/mass spectrometry and gas chromatography sniffing. The aroma produced by fruit body was owing essentially to the presence of octan-3-one and, to a lesser extent, to octan-3-ol. Other compounds, such as oct-1-en-3-ol, oct-1-en, 2-methylbutanol, and alpha-pinene were also present in low concentrations. Comparison of aromatic spectra of the fruit body with that of mycelia obtained under different culture conditions indicated that the main aromatic compounds present in the P. ostreatus fruit body and mycelium were produced in the same proportions on agar surface and on solid support culture, but not under submerged conditions.

Agar↗
PubMed2002

Effects of pulsed electric field processing and storage on the quality and stability of single-strength orange juice.

The effects of pulsed electric field (PEF) processing on microorganisms in orange juice and on the flavor and color of the juice during storage for 112 days at 4 and 22 degrees C were investigated. Single-strength orange juice was PEF processed at an electric field strength of 35 kV/cm for 59 micros and placed into sterilized glass bottles in a sanitary glove box. PEF-processed orange juice was microbiologically stable at 4 and 22 degrees C for 112 days. PEF processing resulted in significant increases in the hydrocarbons D-limonene, alpha-pinene, myrecene, and valencene (P < or = 0.05) but did not have any effect on octanal, decanal, ethyl butyrate, and linalool. The levels of hydrocarbon compounds did not change at 4 and 22 degrees C in 112 days. Octanal, decanal, ethyl butyrate, and linalool levels significantly decreased in 14 days at 4 degrees C and in 2 days at 22 degrees C. The decrease in these compounds did not have a significant effect on the sensory quality of the orange juice (P > or = 0.05). The microorganisms in PEF-processed orange juice, along with the flavor and color of the juice, remained stable at 4 degrees C for 112 days.

Beverages↗
PubMed2002

[Extraction of subfoveal liquid perfluorocarbon].

PURPOSE/METHODS: Perfluorocarbon liquids (PFCL) are synthetic and transparent compounds with a high specific gravity which are very useful for vitreoretinal surgery. Subretinal injection of PFCL can occur during vitreoretinal surgery. A case report is presented of a patient with retained subretinal perfluoro-N-octane following retinal detachment repair for an ocular penetrating injury. RESULTS/CONCLUSION: Perfluoro-N-octane was retained in the subfoveal space for ten postoperative days and was removed thereafter. Based on our experience, residual PFCL droplets in the subretinal space for ten days after retinal detachment surgery allow a good anatomical and visual outcome, after two years follow-up.

Adult↗
PubMed1999

[Study on thermodynamic interactions between polyoctene-1 and solvents using gas chromatography].

Polymer of long chain alpha-olefins is a kind of comb-like polymer with special properties. In this paper, the thermodynamic interactions of polyoctene-1 with eight solvents have been studied by using gas chromatography. The eight Flory-Huggins interaction parameters chi 1 were calculated. The results indicated that chi 1 decreases with increase of the carbon number of linear alkane, but when the carbon number is larger than 8, chi 1 tends to increase with the carbon number. It was also shown that the interaction of polyoctene-1 with cyclohexane is the strongest among all the studied solvents, and that with n-octane is the strongest among the linear alkanes. The relation of interaction parameter (polyoctene-1/n-octane) with temperature T was also determined: chi 1 = 1.697-523.1/T. It was shown that the dissolution of polyoctene-1 in n-octane is an exothermic process with an enthalpy change of -4.84 kJ/mol. The solubility parameter delta 2 of polyoctene-1 is 27.42 (J/mL)1/2, determined from the interaction parameters chi 1.

English Abstract↗
PubMed1976

[Mechanism of action of the specific inhibitor of respiration and phosphorylation in mitochondria--n-(N,N-di-2-chlorethyl)aminophenylacetic acid].

An electrophilous inhibitor, p-(N,N-di-2-chloroethyl)amino-phenylacetic acid (I), specifically disturbs the mechanism of respiration and phosphorylation coupling in mitochondria. I inhibits respiration and ATPase activity in intact mitochondria and does not affect these processes in mitochondria and submitochondrial particles with partially or completely impaired coupling system. The data obtained show that I inhibits protonophoric function of NADH-ferricianide reductase from submitochondrial particles soluble ATPases from bovine heart and Micrococcus lysodeikticus mitochondria adsorded on octane water interface and has no effect on respective enzymes in water solutions. Cation-transferring enzymes are shown to behave with respect to the inhibitor on lipid water interface like respective enzymes in intact mitochondria, while in water solutions they behave like those in systems with the impaired coupling mechanism. Effect of I on protonophoric function of oligomycin-sensitive ATPase and bacteriorhodopsin plaques isolated from Halobacterium halobium is also studied. It is shown that the precence or the absence of I effect is due to a nature of lipid in the enzymatic complex. I is found also to inhibit specifically the transport of Ca2+ from water to octane in the presence of Ca2+-ATP-ase from rabbit sarcoplasmic reticulum.

Adenosine Triphosphatases↗