bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of some N- and S-glycosides of D-galactose bearing hydrazinocarbonyl and diazomethylcarbonyl functions in the aglycon
Authors: Dupuis Gilles , Leclair Benoît
Published: May 2006

We describe the synthesis of N- and S-glycosides derived from D-galactopyranose in which the aglycon bears certain reactive groups. In a first series, the anomeric carbon is linked to an amino group that is acylated by a functionalized succinic acid chain. The terminal group of the aglycon moiety is a hydrazide function which can be converted by ultraviolet light irradiation into an azide and a nitrene. Alternatively, the terminal group is a diazoketone function which can be converted into a carbene, by ultraviolet light irradiation. A second series comprises glycosides of 1-thio-β-D-galactopyranose. The aglycon consists of a 6-carbon chain with a carboxylic end group. The latter has been converted into a hydrazide and diazoketone function. We show that the diazo group of the diazoketones (compounds 5 and 12) is susceptible to decomposition by ultraviolet irradiation, being nearly quantitatively decomposed after 3 minutes. These compounds add to a growing list of hexose derivatives which can be used in the field of photoaffinity-labeling of the sugar binding sites of certain lectins and of hexose transport systems, or to prepare modified proteins or ligands for affinity chromatography.
The gas-phase thermal decomposition of cyclobutanol
Authors: Back R. A.
Published: May 2006

The thermal decomposition of cyclobutanol has been studied in the gas phase in a static system at pressures from 3–6 Torr and temperatures from 250 to 450 °C. The major products observed were ethylene and acetaldehyde, while n-butyraldehyde was a minor product. First-order rate constants based on ethylene formation in a Pyrex vessel conditioned by carbon deposition gave Arrhenius parameters of A = 2.14 (± 0.2) × 1014 s−l and E = 57.3 (± 1) kcal/mol. Under the same conditions, the ratio n-butyraldehyde/ethylene increased with decreasing temperature, corresponding to an activation energy of about 50 kcal/mol for butyraldehyde formation and a frequency factor about 104 times lower than that for ethylene production. In an untreated Pyrex vessel the decomposition showed strong surface catalysis with much lower activation energies for both processes. It is suggested that both ethylene and n-butyraldehyde are formed from a common ĊH2CH2CH2ĊHOH biradical by cleavage and by hydrogen transfer through a 6-membered cyclic transition state respectively. The thermal decomposition is thus the reverse of the Type II and II′ processes observed in the photolysis of n-butyraldehyde.
Complexes formés par addition d'éthers-couronnes aux énolates de Na+ et K+ de l'acétylacétate d'éthyle: structures cristallines et système d'équilibres en solution dans le THF et le DMSO
Authors: Cambillau C. , Bram G. , Corset J. , Riche C.
Published: May 2006

The crystal structure of the ethylacetoacetate (EAA) sodium enolate – 15 crown 5 complex (E−Na+–15C5) is described and compared with the E−K+–18C6 structure already published. Both entities are contact ion pairs externally complexed by the crown. The Na+ cation is out of the mean plane of the crown (1,05 Å). The structure of both complexes is retained in THF solution. The effects observed upon addition of crowns to E−M+ énolates in THF solution (ir and kinetics) or DMSO solution (ir and conductivity) are discussed on the basis of an equilibrium between four ionic species: E−M+, E−||M+, E−M+–C, and E−||M+–C. Some values of equilibrium constants have been determined. Of special interest is the simultaneous presence of the two species E−M+–C and E−||M+–C when crown ether is added in excess. The position of the plateau equilibrium between these two species depends on the nature of the solvent, the cation, and the crown. Some previous results in the literature about alkylation of EAA enolates are rediscussed in relation to this plateau equilibrium.
Absolute rate constants for hydrocarbon autoxidation. 32. On the self-reaction of 1,1-diphenylethylperoxyl in solution
Authors: Howard J. A. , Chenier J. H. B. , Yamada T.
Published: May 2006

The major products of the self-reaction of 1,1-diphenylethylperoxyl have been determined from product studies of the autoxidation of 1,1-diphenylethane, induced decomposition of 1,1-diphenylethyl hydroperoxide, and decomposition of 2,2,3,3-tetraphenylbutane under an atmosphere of oxygen. Overall self-reaction is a complex free-radical process involving the intermediacy of 1,1-diphenylethoxyl and 1-phenyl-1-phenoxyethoxyl which undergo H-atom abstraction, β-scission and, in the case of the former radical, rearrangement. Hydroperoxide decomposition under an atmosphere of 36O2 has shown that 1,1-diphenylethylperoxyl undergoes β-scission faster than α-cumylperoxyl at 303 K in solution. The values of the rate constants for self-reaction of Ph2C(Me)O2• relative to those for tert-butylperoxyl are, however, not affected by this reaction. Furthermore they are not affected to any appreciable extent by the efficiency with which Ph2C(Me)O•, formed in nonterminating self-reactions, escape from the solvent cage. They are influenced principally by the first-order rate of decomposition of Ph2C(Me)OOOOC(Me)Ph2.
The direct electrochemical synthesis of neutral and anionic complexes of thorium(IV)
Authors: Kumar N. , Tuck Dennis G.
Published: May 2006

The electrochemical oxidation of thorium into solutions of halogen (X2; X = Cl, Br) in acetonitrile yields the adducts ThX4•4CH3CN in good yield. With solutions of X2 + R4NX, the products are (R4N)2ThX6. Neutral chelate complexes such as Th(acac)4 (acac = 2,4-pentanedionate) can also be prepared in a one-step synthesis from the metal, but cationic complexes could not be obtained by electrochemical methods.
Theoretical prediction of protein antigenic determinants from amino acid sequences
Authors: Fraga Serafin
Published: May 2006

The locations of the antigenic determinants in a protein are predicted from its amino acid sequence by a modified Hopp–Woods method, proposed in this work, using both hydrophihcity and recognition factors. The amino acid – amino acid interaction energies, from which the recognition factors have been defined, have been evaluated by a semiempirical method, developed at this laboratory, using 1/R expansions parameterized on the basis of the results from accurate SCF calculations. The present procedure, which eliminates most of the uncertainties in the original Hopp–Woods method, leads to a very satisfactory prediction of the antigenic determinants.
Homonuclear one- and two-dimensional nuclear Overhauser effect experiments and spin-echo correlated spectroscopy. Application to prostaglandin E1 and 6-keto-prostaglandin E1
Authors: Kotovych George , Aarts Gerdy H. M.
Published: May 2006

Nuclear Overhauser effect one-dimensional and two-dimensional nuclear magnetic resonance experiments are reported for prostaglandin E1. The two-dimensional nuclear Overhauser effect measurements are combined with spin-echo correlated spectroscopy in order to assign the complete high-field proton magnetic resonance spectrum of 6-keto-prostaglandin E1. The advantages of these two-dimensional techniques are illustrated in these studies. It is also observed that the 6-keto-prostaglandin E1 H-10α proton is substituted more readily by deuterium than are the other protons α to the keto groups.
Troponoid. V. Crystallographic studies on AY-27110 — a dopamine agonist of the troponylpiperazine series
Authors: Ahmed Farid Ramadan , Bagli Jehan
Published: May 2006

The crystal structure and absolute configuration of a p-bromobenzoyl derivative, 2, of the (−)2-[4-[2-hydroxy-2-(3′,4′-dimethyl-phenyl)ethyl]-1-piperazinyl]-2,4,6-cycloheptatrien-1-one, 3a (AY-27110), which is a dopamine agonist, have been determined by an X-ray analysis. Crystals of C28H29BrN2O5, fw = 553.47, are monoclinic P21, a = 12.553(2), b = 6.359(1), c = 17.575(3) Å, β = 108.32(1)°, V = 1331.81 Å3, Z = 2, ρc = 1.380, ρo = 1.384 g cm−3. For 2155 observed reflexions, the final R is 0.036 and R(w) is 0.039. The chirality of this enantiomer is shown to be S(−), based on 18 reflexions with significant differences in the intensities of the corresponding Friedel pairs. The piperazine ring has a distorted chair form that is flattened at the N atom nearest the cycloheptatriene ring as for the psychoactive agents loxapine and amoxapine.
Limiting activity coefficients in dilute solutions of nonelectrolytes. I.Determination for polar–nonpolar binary mixtures by a novel apparatus, and a solubility-parameter treatment of results
Authors: Milanová Etela , Cave Genille C. B.
Published: May 2006

The activity coefficients of several solutes in dilute binary solutions of nonelectrolytes were determined at 20 °C from vapour–liquid equilibria in a novel static equilibration apparatus, by gas-chromatographic analysis of the equilibrium vapor phase. The solutes were nitromethane, nitroethane, 1-nitropropane, 2-nitropropane, acetonitrile, propionitrile, ethyl acetate, and n-butyl acetate in n-heptane and in benzene as solvents, and also carbon tetrachloride as solute in each of the above-listed polar compounds as the solvent.The modifications by Weimer and Prausnitz and by Blanks and Prausnitz to the Scatchard–Hildebrand equation in order to accommodate binary mixtures containing a polar component were tested by using the values found in the present work for the limiting activity coefficients of these solutes. In addition, it was found that the ratio of the dipole – induced dipole interaction parameter for polar solutes in the two nonpolar solvents was nearly constant.Three methods for evaluating the dispersion contribution to the solubility parameter of a polar compound were considered.
Solvent effects on the nitrogen and β-hydrogen hyperfine splitting constants of aminoxyl radicals obtained in spin trapping experiments
Authors: Janzen Edward G. , Coulter Gregory A. , Oehler Uwe M. , Bergsma John P.
Published: May 2006

The nitrogen and β-hydrogen hyperfine splitting constants (hfsc) for phenyl, 4-nitrophenyl, 4-pyridyl, benzoyl, and trichloromethyl spin adducts of α-phenyl tert-butyl nitrone (PBN) as well as for the tert-butoxyl adduct of 5,5-dimethylpyrroline-N-oxide (DMPO) have been obtained as a function of solvent (30 solvents). A useful linear relationship between the β-H hfsc and the N-hfsc of each aminoxyl is found except for the benzoyl adduct of PBN. Some speculations regarding the structural significance of these correlations is presented.
The effect of an external electric field on the photochemistry of x-phthalocyanine particles in heptane
Authors: Harbour John R. , Issler Sandra L.
Published: May 2006

A system is described which allows for the determination of the photo-efficiency of pigment particles in low dielectric solvents as a function of electric field. The charge carriers in this system are both molecular and particulate and the photo-induced current is a function of dissolved oxygen concentration. The maximum quantum efficiency was determined to be 23% at high electric field (2 × 105 V/cm) and low light intensity for x-phthalocyanine particles in heptane. Initial efforts at spin trapping in this system reveal the synergistic generation of a nitroxone and alkylperoxy spin adduct of α-phenyl N-t-butyl nitrone. Both of these adducts are, however, neutral and it is demonstrated that this system is not well suited for the detection of trapped ionic radicals.
Synthesis and Diels–Alder reactions of (E)-6,6-dimethoxy-3-hexen-2-one
Authors: Yates Peter , Douglas Stephen Paul
Published: May 2006

Treatment of 3,3-dimethoxypropanal (2) with (acetylmethylene)triphenylphosphorane (4) gives (E)-6,6-dimethoxy-3-hexen-2-one (5). Reaction of 5 with cyclopentadiene, 1,3-cyclohexadiene, anthracene, and 1,3-diphenylisobenzofuran gives Diels–Alder adducts, which on hydrolysis are converted to the corresponding keto aldehydes. Attempts to effect intramolecular aldol condensation of the latter were unsuccessful. Hydrolysis of the exo-acetyl adduct from 1,3-diphenylisobenzofuran with aqueous formic acid gives 4-acetyl-2,3,3a,4,5,9b-hexahydro-5,9b-diphenylnaphtho[1,2-b]furan-2,5-diol, via aldehyde formation and hydrolytic cleavage of the ether bridge. The adducts from cyclopentadiene under anhydrous acid conditions give 3-acetyl-9-methoxy-tetracyclo[4.3.0.02,4.03,7]nonane(27).
Hydrocarbon ions in fuel-rich, CH4–C2H2–O2 flames as a probe for the initiation of soot: interpretation of the ion chemistry
Authors: Goodings John M. , Tanner Scott D. , Bohme Diethard K.
Published: May 2006

The ion chemistry is discussed for fuel-rich, nearly sooting, methane–oxygen flames at atmospheric pressure with added acetylene. Different types of ion–molecule reactions, both positive and negative, which can contribute through chemical ionization (CI) processes are summarized including their dependence on temperature, pressure, and equivalence ratio [Formula: see text]. Extensive data were presented previously involving ion concentration profiles measured with a mass spectrometer as a function of distance along the axis of conical flames. An understanding of the dominant CI processes provides insight into the early chemical stage of soot formation associated with the flame reaction zone. The negative ion profiles show moderately unsaturated hydrocarbon ions upstream formed by proton transfer followed by progressive dehydrogenation; the highly unsaturated, carbonaceous ions observed downstream appear to arise by two- and three-body electron attachment, charge transfer, and H-atom stripping. The negative hydrocarbon ions can all be explained in terms of polyacetylene derivatives. The same build-up of carbonaceous species downstream is evident from the positive ion profiles. A major role is ascribed to proton transfer reactions with lesser contributions from charge transfer and ion–molecule condensation; three-body association is probably insignificant. Experiments with added acetylene indicate extensive fuel pyrolysis early in the reaction zone. There is no evidence that an ionic mechanism is dominant in forming soot precursors compared with neutral condensation reactions. Because of complexities in the positive ion chemistry, the negative ions appear to provide the more straightforward probe of the underlying neutral chemistry.
Étude, par spectroscopie de vibration, de deux solvants de la cellulose: La N-méthyl morpholine N-oxyde et son monohydrate
Authors: Maï Pham Thi , Herzog-Cance Marie-Hélène , Potier Antoine , Potier Jacqueline
Published: May 2006

The ir and Raman spectra of N-methyl morpholine N-oxide and its monohydrate have been investigated in the frequency range 4000–50 cm−1. For these two compounds, classified among the best cellulose solvents, there exists only the conformer where NO and CH3 groups are respectively in axial and equatorial positions. For anhydrous N-methyl morpholine N-oxide, the dipole–dipole interaction is characterized by a strong line at 75 cm−1 in the Raman spectra.The molecules can be divided into two parts: a hydrophobic part (O(CH2)2) not active in the cellulose dissolution, and a hydrophilic part, which is able to stabilize a chain of water molecules and reveals the importance of the pyramidal environment of water molecules in the monohydrate.
Régiosélectivité de l'hydrogénation catalytique de quelques pyrido[2,3-b]pyrazines
Authors: Cosmao Jean-Marie , Collignon Noel , Queguiner Guy
Published: May 2006

Catalytic hydrogenation on palladium–carbon in ethanol of several pyrido[2,3-b]pyrazines leads to mixtures of the 1,2,3,4- and 5,6,7,8-tetrahydro derivatives except in two cases: the reduction of the nonsubstituted heterocycle takes place on the pyrazine ring and, in the case of the 2,3-diphenyl derivative, the pyridine ring is reduced. In pure acetic acid this reduction provides only 1,2,3,4-tetrahydropyrido[2,3-b]pyrazines. A study of the reduction of 2,3-diphenylpyrido[2,3-b]pyrazine and several di- and tetrahydro derivatives as a function of solvent acidity suggests that the observed selectivity could result from the isomerization of partially hydrogenated intermediates.

[Journal Translation]
Electrochemical reduction of quinoxalino[2,3-b]quinoxaline
Authors: Armand Joseph , Boulares Line , Bellec Christian , Pinson Jean
Published: May 2006

The electrochemical reduction of quinoxalino[2,3-b]quinoxaline gives fluoflavine (2) the structure of which is discussed. The electrochemical reduction of fluoflavine in acidic medium leads to a hexahydroquinoxalino[2,3-b]quinoxaline. A reduction mechanism is proposed based on cyclic voltammetry results and preparative electrolysis. The results obtained in the case of quinoxalino[2,3-b]quinoxaline are used to rationalize the results obtained in the case of pyrazino[2,3-b]pyrazines and pyrazino[2,3-b]quinoxalines.
The synthesis of some 11-substituted tetrahydrocannabinol metabolites
Authors: ApSimon John W. , Collier T. Lee , Guiver Michael D.
Published: May 2006

9-Bromo-11-oxo-hexahydrocannabinol (5) was prepared from the ketocannabinoid 3b via the epoxysulfone 4. The dehydrobromination of the bromoaldehyde 5 could be controlled to give either the thermodynamically more stable Δ8-aldehyde 2c, or the Δ9-aldehyde 1c by an intramolecularly assisted elimination. Reduction of the unsaturated aldehydes gave the allylic alcohol metabolites 2a and 1a, respectively.
The stereochemistry of the enzymic decarboxylation of L-arginine and of L-ornithine
Authors: Richards James C. , Spenser Ian D.
Published: May 2006

The decarboxylation of L-ornithine to yield putrescine, catalyzed by the L-ornithine decarboxylase (EC 4.1.1.17) of E. coli, and the decarboxylation of L-arginine to yield agmatine, catalyzed by the L-arginine decarboxylase (EC 4.1.1.19) of E. coli, take place with retention of configuration.
Synthèse stéréospecifique de nucléosides pyrimidiques par la méthode de Hilbert–Johnson
Authors: Gagnieu Christian H. , Grouiller Annie V. , Pacheco Henri
Published: May 2006

Condensation of 2,4-dimethoxy pyrimidine with bromoglucosides derived from methyl 4-deoxypentopyranosides 2–7 and from 3,5,6-tri-O-benzoyl glucofuranose, 20, leads in a stereospecific manner to the nucleosides 8–13 and 22 with the trans 1′,2′ configuration. The stereochemistry of this reaction is not influenced by the structure of the starting sugar but rather is directed by the presence of the C-2 hydroxyl group. The synthesis of epoxide 18, obtained by the action of NaH on the bromohydrine 17, derived from 7, supports the intervention of a reaction assisted by an epoxide-like intermediate derived from the trans-bromohydrine. On the other hand, the cis-bromohydrine undergoes direct substitution of anomeric halogen by base. The possibility of the formation of a carbocation-like intermediate is discounted since SN1 type glycosylation reactions of 19 by MeOH or t-BuOH lead preferentially to products with the cis-configuration.

[Journal translation]
Molecular rearrangements. III. Thermal decomposition of some selected thioesters
Authors: Abdel-Wahab Aboel-Magd A. , El-Khawaga Ahmed M. , Ismail Mohamed T.
Published: May 2006

Four selected thioesters (1–4) were prepared and pyrolyzed in the absence of promoters either alone or in isoquinoline solvent. These esters include benzyl thiobenzoate (1), phenyl phenylthioacetate (2), benzyl phenylthioacetate (3), and phenyl thiobenzoate (4). Pyrolysis of 1 gave mainly 2,3,4,5-tetraphenylthiophene in addition to benzene, biphenyl, benzyl thiol, and benzoic acid. Thermal decomposition of 1 under nitrogen gave benzaldehyde, benzil, and only a trace of benzoic acid in addition to the former products. Compound 2 afforded essentially toluene and dibenzyl in addition to benzene, biphenyl, phenyl sulphide, thiophenol, and phenyl acetic acid. Thermolysis of 3 gave toluene and stilbene beside small quantities of benzyl thiol and phenylacetic acid. Finally, thermal decomposition of 4 in isoquinoline gave benzene, biphenyl, phenyl sulphide, thianthrene, thiophenol, benzoic acid, and 1-phenylisoquinoline. H2S and CO are also produced in all cases. In these rearrangements, the C—S bonds undergo homolytic fission either simultaneously or selectively. No isomer redistribution precedes the coupling reactions. Plausible mechanisms for the above facts are proposed.
Mise en évidence de la formation d'hydrogène par la réaction de recombinaison bimoléculaire des radicaux HO2. Réaction hétérogène de basse température des radicaux HO2
Authors: Sahetchian Krikor A. , Heiss Adolphe , Rigny Renée
Published: May 2006

It is shown that there is practically no reaction of HO2 radicals on walls of quartz or Pyrex glass, coated or not with boric acid, at temperatures higher than the ambient one, whereas at lower temperatures these radicals disappear. The rate of disappearance increases with decreasing temperature, contrary to what occurs at high temperature (t > 150 °C). The apparent coefficient of heterogeneous recombination may be expressed by γa = 1.9 × 10−11 exp (11 000/RT). By using, as a new thermal source of HO2 radicals, the system O2 + 10 ppm of C7H15O—OC7H15 (t 220–240 °C, quartz vessel coated with B2O3 and treated by the slow reaction H2/O2, HO2 radicals formed through the reaction C7H15O + O2 → HO2 + product), it was possible to study the bimolecular recombination reaction of HO2 radicals. The formation of molecular hydrogen was shown; we deduce from this that the recombination reaction produces H2O2, and H2 by two competitive paths:[Formula: see text]
Thermolysis of 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline
Authors: Hitchcock A. P. , Zweep S. , Steel T. , Békhazi M. , Warkentin J.
Published: May 2006

The principal product of gas phase thermal decomposition of 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline (methoxyoxa-diazoline) was found to be 1-methoxy-1-[(1-methylethenyl)oxy]-ethane (vinyl ether). This arises from a selective 1,4-hydrogen shift in the carbonyl ylide intermediate. Fragmentation of the carbonyl ylide is the dominant process in the solution thermolysis of methoxyoxadiazoline. The phase and temperature dependence of this thermolysis is discussed in terms of the probable structure of the carbonyl ylide intermediate.
The phosphorus-31 and metal nuclear magnetic resonance spectra of complexes of tin(II) and lead(II) with tricyclohexylphosphine oxide, sulfide, and selenide
Authors: Dean Philip A. W.
Published: May 2006

The new stannous and plumbous complexes M(OP(C6H11)3)n2+ (n = 2 or 3, M = Sn or Pb) and [M(SP(C6H11)3)x(SeP-(C6H11)3)3−x]2+ (M = Sn or Pb) have been prepared in SO2 solution and characterized by their reduced temperature slow-exchange 31P and metal (119Sn or 207Pb) nmr spectra. No evidence could be found for complexes in which both OP(C6H11)3 and EP(C6H11)3 (E = S or Se) are coordinated to tin(II) or lead(II). The same pattern of chemical shifts is found in the 119Sn and 207Pb nmr spectra: δM(M(OP(C6H11)3)22+) < δM(M(OP(C6H11)3)32+ < δM(M(SP(C6H11)3)32+) < δM(M(SeP(C6H11)3)32+) and a monotonic but non-linear variation of δM with x for [M(SP(C6H11)3)x(SeP(C6H11)3)3−x]2+. From M(AsF6)2 in SO2 as reference, the range of the metal chemical shifts is 999–2079 ppm and 2407–7707 ppm in the 119Sn and 207Pb nmr spectra respectively. In the 31P nmr spectra, all of the appropriate two-bond M—P couplings are observed, but the fine structure expected from coupling to 31P could not always be observed in those metal nmr spectra which were measured at high field; it is suggested that these metal nmr spectra are "smeared out" by a combination of large temperature sensitivity of the metal chemical shifts and the small temperature variation allowed by the nmr spectrometer temperature controller and/or diffusion along any temperature gradients present along the length of the nmr sample.
Arylallyl cations and their stereospecific cyclization to bicyclic trienylic cations
Authors: Dytnerski D. M. , Ranganayakulu K. , Singh B. P. , Sorensen T. S.
Published: May 2006

A series of arylallyl alcohols, where aryl = 2,6-dimethylphenyl, mesityl, duryl, or pentamethylphenyl, was prepared. On addition to strong acid, these generate arylallyl cations. In some cases these allyl cations are observable and were characterized as insitu solution species by nmr spectroscopy. In other cases, an immediate cyclization takes place, leading stereospecifically to a series of bicyclic trienyl cations, which were also thoroughly characterized. The stereochemistry of this cyclization reaction, which was initially expected to follow the "rules" for electrocyclic ring closures, was probed in some detail. It is tentatively concluded that the stereochemistry in the products is not that expected from a conrotatory ring closure. Two diarylmethyl cations were also prepared. However, these did not cyclize.
Biologically active acyclonucleoside analogues. II. The synthesis of 9-[[2-hydroxy-1-(hydroxymethyl)ethoxy]methyl]guanine (BIOLF-62)
Authors: Ogilvie Kelvin K. , Cheriyan Ukken O. , Radatus Bruno K. , Smith Kendall O. , Galloway Karen S. , Kennell Wiebke L.
Published: May 2006

The chemical synthesis of 9-[[2-hydroxy-1-(hydroxymethyl)ethoxy]methyl]guanine is described. This compound, known as BIOLF-62, is active against herpesviruses. This compound is a member of a novel class of nucleoside analogues which lack a rigid carbohydrate ring, but which possess all of the functional groups of naturally occurring deoxynucleosides.
Thermochemical parameters for organic radicals and radical ions. Part 2. The protonation of hydrocarbon radicals in the gas phase
Authors: Nicholas A. Martin de P. , Boyd Russell J. , Arnold Donald R.
Published: May 2006

A thermochemical cycle is used to estimate the gas phase acidity of several hydrocarbon radical cations: hydrocarbon radical cation (pKa), methane (≥ 86.5 ± 1), ethane(101 ± 1, 102 + 1), ethylene (≥ 125 ± 2), acetylene (118 ± 3, 122 ± 1), propene(124 ± 1, 122 ± 1), cyclopropane (≥ 134, ≥ 131), benzene (147 ± 1), and toluene (139 ± 1, 140). Similarly, proton affinities of the conjugate base, the hydrocarbon radical, are estimated.An estimate of the proton affinity is obtained using abinitio MO calculations. A Hartree–Fock proton affinity, PAHF(R•)g is defined as the difference in the computed energies of a radical cation and its conjugate base at the Hartree–Fock level. Calculations at the SCF level are carried out using both the minimal (STO-3G) and extended basis sets, without (3-21G, 4-31G, and 6-31G) and with (4-31G* and 6-31G*) polarization functions on carbon.The agreement between the thermochemical and abinitio estimates of the proton affinity is satisfactory.
Studies on reaction kinetics and on 82Br exchange in the solvolysis of triphenylvinyl bromide or trianisylvinyl bromide in 70% HOAc – 30% H2O
Authors: Lee Choi Chuck , Obafemi Craig A. , Rappoport Zvi
Published: May 2006

Studies were carried out on the kinetics of solvolysis of triphenylvinyl bromide (1-Br) or trianisylvinyl bromide (2-Br) in 70% HOAc – 30% H2O in the presence of added Et4NBr, NaOAc, or LiClO4 and on the degree of incorporation of 82Br-labeled bromide into 1-Br or 2-Br during the solvolysis. Common ion rate depression and 82Br exchange were observed for both substrates, indicating the involvement of the dissociated triphenylvinyl and trianisylvinyl cations. For both substrates, a normal salt effect was found for NaOAc and LiClO4. With NaOAc, there was also a steeper rise in rate at low concentrations of added salt, but this initial rate enhancement was only 11 and 13%, respectively, for 1-Br and 2-Br, and the fact that LiClO4 showed only a normal salt effect suggested that probably there was no special salt effect for NaOAc. These results, considered in conjunction with previous scrambling data, led to the suggestion that the previously observed insensitivity of the extent of isotopic scrambling in the solvolysis of 1-Br-2-14C may be due to a low selectivity for the less stable triphenylvinyl cation.
Metal ion – biomolecule interactions. IV. Methylmercury(II) complexes of l-methylimidazoline-2-thione (methimazole), a potentially useful protective agent in organomercurial intoxication
Authors: Buncel Erwin , Norris Albert R. , Taylor Spencer E. , Racz William J.
Published: May 2006

Two 1:1 methylmercury(II)-1-methylimidazoline-2-thione (methimazole, MeImSH) complexes, [MeHg(MeImSH)]NO3 and [MeHg(MeImS)], have been isolated from aqueous solution under acidic and basic conditions, respectively. 1H nmr and ir spectroscopy, as well as analytical data, were used to characterize the complexes. The nmr data, in particular, lead to the conclusion that the principal binding mode under both sets of conditions involves the sulfur atom at C2. However, under conditions of 2:1 (MeHgII:MeImSH) stoichiometry, binding to N3 is also found to occur. These interpretations have necessitated a reexamination of the 1H nmr spectrum of the free ligand, in particular with respect to assignment of NH and SH resonances corresponding to the two possible tautomeric forms. It has been found in this work that 1-methylimidazoline-2-thione shows a high affinity for MeHgII binding, which may be pertinent with respect to a previous report concerning the protective nature of this compound in organomercurial intoxication.
Kinetics of the reaction C2H5 + H2 → C2H6 + H from 1111-1200 K
Authors: Cao J.-R. , Back M. H.
Published: May 2006

A system for the measurement of the rate constant for the elementary reaction[Formula: see text]in the temperature range 1111–1200 K is described and is based on the thermal production of an equilibrium concentration of hydrogen atoms. In a mixture of hydrogen with about 10 ppm ethylene this reaction is the rate-controlling step in the hydrogenation of ethylene. The product ethane undergoes rapid secondary dissociation and the final product is methane. The values obtained in the present work, which are represented by the following expression,[Formula: see text](R = 1.987 cal mol−1 deg−1) are compared to those obtained at lower temperature (820–350 K) and to those calculated from measurements of the reverse reaction.
Halogenation of 1,6-diazaphenalene. Theoretical and experimental results
Authors: Weber Robert W. , Lee Shieu-Jeing , Milosevich Samuel , England Walter B. , Cook James M.
Published: May 2006

Bromination of 1,6-diazaphenalene 1 yields a mixture of mono-, di-, and tri-bromo derivatives, while bromination of the conjugate acid 2 provides the 7-bromo isomer 7 in 81% yield. Charge densities and localization energies have been calculated, and are found to be in agreement with the orientation pattern observed during electrophilic substitution. These observations have been employed to develop several routes to 7-substituted 1,6-diazaphenalenes.
Synthesis of (−)- and (+)-2-hydroxy-6-keto-N-methylmorphinans, their O-methyl ethers, and 2-deoxy congeners
Authors: Schmidhammer Helmut , Brossi Arnold
Published: May 2006

Bischler–Napieralski cyclization of the known phenylacetamide 1, followed by selective ether cleavage of the 3,4-dihydroisoquinoline 2 and sodium borohydride reduction, afforded the tetrahydroisoquinoline 4. Optical resolution of 4 with tartaric acid gave the optical isomers 4a,b, which were converted into the 6-ketomorphinans 9a,b and their O-methyl ethers 10a,b by the following reaction sequence: Birch reduction, N-formylation of the dihydro bases, Grewe cyclization, removal of the N-formyl protecting groups, reductive N-methylation, and O-methylation. The 2-deoxy congeners 12a,b were obtained from 9a,b by phenyltetrazolylation, and catalytic removal of the heterocyclic etherfunction. The (−)-enantiomer 12a obtained by this synthesis was identical with material prepared from natural morphine, and exhibited the high antinociceptive potency already reported.
Changes in Levels of Serum Insulin, C-Peptide and Glucose after Electroacupuncture and Diet Therapy in Obese Women
Authors: Cabıoğlu Mehmet Tuğrul , Ergene Neyhan
Published: May 2006

Our purpose was to investigate the effects of electroacupuncture (EA) therapy on body weight and on levels of serum insulin, c-peptide and glucose in obese women. 52 healthy women were included in this study and were allocated into three groups: 1) Placebo EA group ( n = 15; mean age = 41.8 ± 4.6 and mean body mass index { BMI } = 33.2 ± 3.5); 2) EA group ( n = 20; mean age = 42.1 ± 4.4 and BMI = 35.9 ± 3.6) and 3) Diet restriction group ( n = 20; mean age = 42.9 ± 4.3 and BMI = 34.7 ± 2.7). EA was applied to the ear points Hunger and Shen Men on alternating days and to the body points LI 4, LI 11, St 36 and St 44 once a day for 30 minutes over 20 days. Diet restriction that entailed a 1450 kilocalorie (kcal) diet program was applied to the three groups for 20 days. An increase in weight loss was observed when weight loss in the EA group (p < 0.000) was compared to that in the diet restricted and placebo EA groups using the Tukey HSD test. There were increases in the serum insulin (p < 0.001) and c-peptide levels (p < 0.000) in the women treated with EA compared to those in the women treated with the placebo EA and diet restriction groups. A decrease was observed in the glucose levels (p < 0.01)in both the EA and diet restriction groups compared to those in the placebo EA group. Our results suggest that EA therapy is an effective method in treating obesity. EA therapy also helps serum glucose levels to decrease through the increase of serum insulin and c-peptide levels.
Acupuncture for Diagnostic Fiberoptic Bronchoscopy: A Prospective, Randomized, Placebo-Controlled Study
Authors: Cabrini Luca , Gioia Luigi , Gemma Marco , Melloni Giulio , Carretta Angelo , Ciriaco Paola , Puglisi Armando
Published: May 2006

Patients usually fear fiberoptic bronchoscopy (FBS) and they report a low level of satisfaction after this examination. We evaluated the efficacy of acupuncture in decreasing patient anxiety before diagnostic FBS and in improving tolerance to the examination. In a prospective double-blind study, we enrolled 48 patients scheduled to undergo diagnostic FBS. Patients were randomly assigned to one of three groups. Group A (16 patients): standard FBS, with airway topic anesthesia; Group B (16 patients): standard FBS, with airway topic anesthesia and acupuncture treatment; Group C (16 patients): standard FBS, with airway topic anesthesia and sham acupuncture. EKG, non-invasive arterial pressure, and pulse oximetry were monitored on a routine basis. We evaluated patient anxiety before and after acupuncture and, at the end of FBS, the discomfort suffered during the examination by a 100-mm Visual Analog Scale (VAS).

Patient satisfaction in Group A was 50% worse than in Group B ( p = 0.04). We observed a strong, even if not statistically significant, tendency toward a lower pre-FBS anxiety in Group B. Patients in group C had values very close to those recorded in group A. We observed no adverse event and no differences in cardio-respiratory parameters in these three groups; in particular, we did not observe a respiratory depression in Group B.

Acupuncture seems an effective resource for a Thoracic Endoscopic Room to improve patient tolerance to FBS.
Neurons in the NTS of Rat Response to Gastric Distention Stimulation and Acupuncture at Body Surface Points
Authors: He Junfeng , Yan Jie , Chang Xiaorong , Liu Jianhua , Li Jianshan , Yi Shouxiang , Lin Yaping
Published: May 2006

The nucleus of the solitary tract (NTS) is a primary center, not only for receiving visceral afferents, but also for somatic afferents. Previous experiments demonstrated that NTS might be a primary afferent center for connecting the Stomach Meridian (ST Medirian) and the Stomach. In this study, an extracellular recording method was used to analyze the firing neurons. The variety of NTS' neurons' responses to gastric distention (GD) and different body surface points were compared. In 52 rats, 104 firing neurons of NTS were recorded, in which there were 47 GD related neurons. For the 47 GD related neurons, there were 33 neurons responsive to acupuncture at Sibai (ST 2, belonging to ST Meridian). Therefore, in the 47 GD related neurons, the response neuron occurring rate (RNOR) for acupuncture at ST 2 was 70.21%. Meanwhile in the 47 GD related neurons, when acupuncture was performed at Quanliao (SI 18, belonging to Small Intestine Meridian) and non-acupoint respectively, there were 18 and 17 firing neurons, and the RNOR were 38.30% and 36.17% respectively. The experiment demonstrated that there were some varieties in the response of NTS neurons to GD stimuli and acupuncture at different body surface points, which suggested that the ST Meridian was more intimately linked to the Stomach and that the different acupoints do have some specificity.
The Study of Dynamic Response to Acute Hemorrhage by Pulse Spectrum Analysis
Authors: Chang Yu Hsin , Tsai Chia I , Lin Jaung Geng , Lin Yue Der , Li Tsai Chung , Su Yi Chang
Published: May 2006

Traditional Chinese Medicine (TCM) holds that Blood and Qi are fundamental substances in the human body for sustaining normal vital activity. The theory of Qi, Blood and Zang-Fu contribute the most important theoretical basis of human physiology in TCM. An animal model using conscious rats was employed in this study to further comprehend how organisms survive during acute hemorrhage by maintaining the functionalities of Qi and Blood through dynamically regulating visceral physiological conditions. Pulse waves of arterial blood pressure before and after the hemorrhage were taken in parallel to pulse spectrum analysis. Percentage differences of mean arterial blood pressure and harmonics were recorded in subsequent 5-minute intervals following the hemorrhage. Data were analyzed using a one-way analysis of variance (ANOVA) with Duncan's test for pairwise comparisons. Results showed that, within 30 minutes following the onset of acute hemorrhage,the reduction of mean arterial blood pressure was improved from 62% to 20%. Throughout the process, changes to the pulse spectrum appeared to result in a new balance over time. The percentage differences of the second and third harmonics, which were related to kidney and spleen, both increased significantly than baseline and towards another steady state. Apart from the steady state resulting from the previous stage, the percentage difference of the 4th harmonic decreased significantly to another steady state. The observed change could be attributed to the induction of functional Qi, and is a result of Qi-Blood balancing activity that organisms hold to survive against acute bleeding.
Protective Effect of Total Flavones of Rhododendra on Ischemic Myocardial Injury in Rabbits
Authors: Yuan Li-Ping , Chen Zhi-Wu , Li Fan , Dong Liu-Yi , Chen Fei-Hu
Published: May 2006

This study was to investigate the effect of total flavones of rhododendra (TFR) on ischemic myocardial injury in rabbits. Rabbit ischemic myocardial injury was induced by occluding the anterior descent of the left artery (LAD). The ECG was recorded; the plasma creatine kinase (CK), nitric oxide (NO) and endothelin-1 (ET-1) levels were measured using spectrophotometry, Griess method and radioimmunoassay, respectively. The myocardial ischemic size and infarction size were determined by dual staining with Evan's blue and Nitroblue tetrazolium reductionest (N-BT). A typical ECG S-T segment elevation and an increase of plasma CK activity were observed 6 and 24 hours after the induction of ischemia. These changes were inhibited in rabbits treated with either TFR (30, 60 mg/kg) or ginkgo biloba extract (EGB) for 7 days, indicating a protective effect of TFR on ischemic myocardial injury. The myocardial ischemic size and infarction size were 40.7 ± 3.6% and 36.8 ± 3.6% respectively in the control group, while TFR (60 mg/kg) pretreatment for 7 days significantly reduced both myocardial ischemic size (32.40 ± 5.38%, p < 0.05) and infarction size (28.7 ± 5.8%, p < 0.05). In addition, the occlusion of LAD resulted in an increase of ET-1 and a decrease of NO levels in the plasma, effects that were inhibited by TFR treatment, suggesting a possible mechanism for the protective effect of TFR against myocardial ischemic injury.
Cardiac Protective Effect of Astragalus on Viral Myocarditis Mice: Comparison with Perindopril
Authors: Chen Xiang-Jian , Bian Zhi-Ping , Lu Shu , Xu Jin-Dan , Gu Chun-Rong , Yang Di , Zhang Ji-Nan
Published: May 2006

In clinical practice, Astragali Radix (Astragalus), the root of Astragalus membranaceus Bunge, has been widely applied to treat patients with viral diseases, including viral myocarditis in China. The present study was designed to evaluate the protective effects of Astragalus on the function of sarcoplasmic reticulum calcium ATPase (SERCA2) activity and endothelin system at acute and chronic periods of myocarditis mice induced by CVB 3 infection. Astragalus feeding (2.2 mg/kg/day) could significantly increase the survival rate, alleviate pathological alterations and serum cardiac troponin I (cTnI), as well as restore impaired SERCA activity at the acute stage. Low affinity and capacity of ETR were reversed with Astragalus after the first CVB 3 inoculation up to 7 days and after the second virus inoculation up to 150 days. In the meantime, the contents of cardiac ET-1 and ANP were reduced. Comparison the myocarditis mice treated with Perindopril (0.44 mg/kg/day), an ACE inhibitor, shows that Astragalus achieved a similar effect on survival rate, SERCA2 and ET system. These results indicated that the beneficial effects of Astragalus and Perindopril for treating viral myocarditis might be partly mediated by preserving the functions of SERCA 2 activity and ET system.
SUM RULES FOR DEEP-INELASTIC ELECTROWEAK PRODUCTION
Authors: FAYYAZUDDIN  , RIAZUDDIN
Published: May 2006

Using light-cone algebra, various sum rules for electroweak structure functions are derived. These sum rules are examined in the context of the quark and gluon contents of the proton.
A MODEL FOR PREDICTING THE EFFECTIVE THERMAL CONDUCTIVITY OF NANOPARTICLE-FLUID SUSPENSIONS
Authors: MURSHED S. M. S. , LEONG K. C. , YANG C.
Published: May 2006

The uniformity and homogeneously dispersed nanoparticles in base fluids contribute to enhanced thermal conductivity of the mixture. By considering the uniformity and geometrical structures (e.g., body-centered cubic) of homogeneously dispersed nanoparticles in base fluids, a model for determining the effective thermal conductivity (ETC) of such nanoparticle-fluid suspensions, commonly known as nanofluids is proposed in this study. The theoretical results of the effective thermal conductivities of TiO 2/Deionized (DI) water and Al 2 O 3/DI water-based nanofluids are presented, and they are found to be in good agreement with our experimental results and also with those reported in the literature. The new model presented in this study shows a better prediction of the effective thermal conductivity of nanofluids compared to other classical models attributed to Maxwell, Hamilton–Crosser, and Bruggeman.
MECHANOCHEMICAL SYNTHESIS OF CADMIUM-DOPED TIN OXIDE NANOPARTICLES
Authors: YANG HUAMING , SU XIAOHUI , TANG AIDONG
Published: May 2006

The cadmium-doped SnO 2 nanoparticles have been successfully prepared by a simple mechanochemical reaction and subsequent thermal treatment. The samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Thermal treatment of the as-milled powder at 700°C for 2 h resulted in the formation of Cd-SnO 2 nanoparticles with an average crystal size of 13 nm, varying with the calcination temperature. The effect of doped cadmium on the crystal size of the nanoparticles was investigated. The lattice parameter (c) of the Cd-SnO 2 nanoparticles, lower than that of pure SnO 2, decreased with increasing amount of doped cadmium. The apparent activation energy of Cd-SnO 2 nanocrystal growth during calcination of the precursor was calculated to be 70.8 kJ/mol. The mechanochemical method is a novel, cheap and convenient technique especially suitable for large-scale synthesis of nanosized materials.
THE EFFECT OF TEMPERATURE AND RELATIVE HUMIDITY ON PATTERNING OF A FERROELECTRIC POLYMER P(VDF-TrFE) VIA DIP-PEN NANOLITHOGRAPHY
Authors: TANG Q. , SHI S. Q. , ZHOU L. M.
Published: May 2006

This paper reports the effect of temperature and relative humidity on the patterning of a ferroelectric polymer poly(vinylidene fluoride-trifluorethylene) [P(VDF-TrFE 80:20)] onto a gold substrate via dip-pen nanolithography (DPN). It is found that temperature plays a significant role in this system, that the transport rate of P(VDF-TrFE) increases as the temperature increases, and that the diffusion length increases linearly with the square root of time at all of the measured temperatures. A critical temperature of 55°C is observed, above which, the transport rate of P(VDF-TrFE) increases significantly, and the interaction forces between the probe tip and P(VDF-TrFE) and between P(VDF-TrFE) and the gold substrate decrease. It is suggested that a phase transition at about 55°C may have happened in the thin film of P(VDF-TrFE). The influence of relative humidity on the transport rate of the hydrophobic P(VDF-TrFE) is small.
OLIGOSACCHARIDE FUNCTIONALIZED NANOFIBROUS MEMBRANE
Authors: KAUR S. , KOTAKI M. , MA Z. , GOPAL R. , RAMAKRISHNA S. , NG S. C.
Published: May 2006

An attempt was made to incorporate β-Cyclodextrin (β-CD) onto the surface of the nanofiber to target potential applications in organic waste treatment. Phenylcarbomylated and azido phenylcarbomylated β-CD were successfully blended with poly(methyl methacrylate) (PMMA) and electrospun into nanofibrous membrane respectively with an approximate diameter of 900 nm. The presence of this selective agent on the surface of the nanofibers was confirmed by ATR-FTIR and XPS. To determine the functionalized membranes ability to capture small organic molecules, a solution containing phenolphthalein (PHP), a small organic molecule, was used. The results obtained showed that the functionalized nanofibrous membranes were able to effectively capture the PHP molecules. Thus the developed β-CD functionalized nanofibrous membranes may have the potential to capture similar small organic molecules in organic waste.
Mechanism of insulin's anabolic effect on muscle: measurements of muscle protein synthesis and breakdown using aminoacyl-tRNA and other surrogate measures
Authors: Chow Lisa S. , Albright Robert C. , Bigelow Maureen L. , Toffolo Gianna , Cobelli Claudio , Nair K. Sreekumaran
Published: May 2006

Despite being an anabolic hormone in skeletal muscle, insulin's anticatabolic mechanism in humans remains controversial, with contradictory reports showing either stimulation of protein synthesis (PS) or inhibition of protein breakdown (PB) by insulin. Earlier measurements of muscle PS and PB in humans have relied on different surrogate measures of aminoacyl-tRNA and intracellular pools. We report that insulin's effect on muscle protein turnover using aminoacyl-tRNA as the precursor of PS and PB is calculated by mass balance of tracee amino acid (AA). We compared the results calculated from various surrogate measures. To determine the physiological role of insulin on muscle protein metabolism, we infused tracers of leucine and phenylalanine into 18 healthy subjects, and after 3 h, 10 subjects received a 4-h femoral arterial infusion of insulin (0.125 mU·kg−1·min−1), while eight subjects continued with saline. Tracer-to-tracee ratios of leucine, phenylalanine, and ketoisocaproate were measured in the arterial and venous plasma, muscle tissue fluid, and AA-tRNA to calculate muscle PB and PS. Insulin infusion, unlike saline, significantly reduced the efflux of leucine and phenylalanine from muscle bed, based on various surrogate measures which agreed with those based on leucyl-tRNA (−28%), indicating a reduction in muscle PB ( P < 0.02) without any significant effect on muscle PS. In conclusion, using AA-tRNA as the precursor pool, it is demonstrated that, in healthy humans in the postabsorptive state, insulin does not stimulate muscle protein synthesis and confirmed that insulin achieves muscle protein anabolism by inhibition of muscle protein breakdown.