bluuebunny/crossref_metadata_2025 huggingface dataset:
Clonal Composition of
Staphylococcus aureus
Isolates at a Brazilian University Hospital: Identification of International Circulating Lineages
Authors: Vivoni Adriana Marcos , Diep Binh An , de Gouveia Magalhães Ana Cristina , Santos Kátia Regina N. , Riley Lee W. , Sensabaugh George F. , Moreira Beatriz M.
Published: May 2006

In only a few instances has the clonal composition of
Staphylococcus aureus
collections that include methicillin-susceptible
S. aureus
(MSSA) been extensively characterized. In order to investigate the clonal composition of MSSA and methicillin-resistant
S. aureus
(MRSA) and examine whether the infections diagnosed at our hospital were related to internationally distributed
S. aureus
lineages, we collected 89 clinical
S. aureus
isolates from patients at a public university hospital in Rio de Janeiro, Brazil, from September 1999 to June 2000. All
S. aureus
isolates were genotyped by pulsed-field gel electrophoresis and multilocus restriction fragment typing (MLRFT), and a subset (
n
= 17) was further characterized by multilocus sequence typing (MLST). The 34 MRSA isolates were additionally characterized by SCC
mec
typing. The MSSA population (
n
= 55) was grouped into 18 restriction fragment types (RFTs); of these, five RFTs accounted for 67% (37) of the MSSA isolates. MRSA isolates were clustered into only three RFTs (
P
= 0.02). The majority of MSSA RFTs were related to sequence type 30 (ST30) (12 isolates, 22%), ST1, ST188, and ST432 (6 isolates, 11% each). The predominant MRSA RFT comprised 31 (91%) of 34 isolates; four randomly selected isolates of this RFT were ST239, the previously described widely disseminated Brazilian clone. However, a fifth isolate belonging to this RFT was the ST644, a new single locus variant of ST239. By applying MLRFT and MLST, we found evidence for a clonal structure in MSSA isolates and detected the dissemination of MSSA clonal complexes 1, 5, 8, 30, and 45.
Evaluation of the GenoType Mycobacterium Assay for Identification of Mycobacterial Species from Cultures
Authors: Richter Elvira , Rüsch-Gerdes Sabine , Hillemann Doris
Published: May 2006

A new commercially available DNA strip assay (GenoType Mycobacterium CM/AS; Hain Lifescience, Nehren, Germany) was evaluated for the ability to differentiate mycobacterial species. The test is based on a PCR technique targeting a 23S rRNA gene region, followed by reverse hybridization and line probe technology. The GenoType CM is capable of identifying 23, the GenoType AS a further 14, species either alone or in combination with one or more species. Both tests were evaluated with 156 mycobacterial strains composed of 61 validly published species including different subspecies, 6 not validly published species, and 3 strains other than mycobacterial species. All strains were precharacterized by sequencing of the 5′ region of the 16S rRNA gene and biochemical tests. In total, results for 151 strains were interpretable. Concordant results were obtained for 137 (92.6%) of 148 mycobacterial strains with the CM assay and 133 (89.9%) of 148 mycobacterial strains with the AS assay, and all three non-Mycobacteriumspecies were identified.
Evaluation of a Novel Highly Sensitive, Broad-Spectrum PCR-Reverse Hybridization Assay for Detection and Identification of Beta-Papillomavirus DNA
Authors: de Koning Maurits , Quint Wim , Struijk Linda , Kleter Bernhard , Wanningen Patrick , van Doorn Leen-Jan , Weissenborn Sönke Jan , Feltkamp Mariet , ter Schegget Jan
Published: May 2006

Human papillomavirus can be detected by amplification of viral DNA. A novel one-step PCR (PM-PCR) was evaluated for amplification of a 117-bp fragment from the E1 region. It permitted ultrasensitive detection of all 25 known human papillomavirus genotypes from the beta-papillomavirus genus. The intra- and intertypic sequence variations of the 77-bp interprimer region were studied. Genotype-specific probes as well as general probes were selected for the 25 established beta-papillomavirus types, and a reverse hybridization assay (RHA) was developed (PM-PCR RHA method). The analytical sensitivity of the PM-PCR RHA method was 10 to 100 viral genomes. The one-step PM-PCR turned out to be more sensitive than the previously described nested MaHa-PCR for beta-papillomavirus detection. The PM-PCR RHA method was able to detect and identify beta-papillomavirus types in frozen patient material as well as in poorly amplifiable material such as formalin-fixed, paraffin-embedded skin biopsy specimens. Inter- and intralaboratory variability experiments showed that the reproducibility of the assay was very high. In conclusion, the one-step PM-PCR together with the RHA allows extremely sensitive, specific, and reproducible detection of beta-papillomavirus DNA as well as reliable identification of beta-papillomavirus genotypes in both fresh and paraffin-embedded patient material.
G8Rotavirus Strains Isolated in the Democratic Republic of Congo Belong to the DS-1-Like Genogroup
Authors: Matthijnssens Jelle , Rahman Mustafizur , Yang Xuelei , Delbeke Thomas , Arijs Ingrid , Kabue Jean-Pierre , Muyembe Jean-Jacques Tamfum , Van Ranst Marc
Published: May 2006

Several G8P[6] and G8P[8] rotavirus strains were isolated from hospitalized patients in the Democratic Republic of Congo in 2003. To investigate their overall genomic relatedness and to determine to which genogroup they belonged, the complete genomes of strains DRC88 (G8P[8]) and DRC86 (G8P[6]) were determined. Genomic comparison of these two African G8 strains revealed that 10 out of their 11 gene segments, except for VP4, were nearly identical (>98.9% identical at the nucleotide level), suggesting that this rare G8P[8] rotavirus strain originated recently from a reassortment between a common G8P[6] strain and a strain with a P[8] specificity. A very close evolutionary relationship between 9 out of the 11 gene segments of DRC88 and DRC86 and rotavirus strains belonging to the DS-1-like (G2P[4]) “genogroup” was found, and several possible reassortment events preceding the occurrence of G8P[8] and G8P[6] human rotaviruses were hypothesized. Since the genes of G2P[4] rotavirus strains are very well adapted to infect humans, the acquirement of a new VP7 (G8) gene, and especially the replacement of P[6] (believed to be of animal origin) by P[8] (most common in human rotaviruses), might make DRC88-like rotaviruses very well equipped to become a predominant human rotavirus strain and an important pathogen on the African continent and the rest of the world. These findings have important implications for rotavirus vaccine development and highlight that typing of new rotavirus strains by
merely sequencing their VP7 and VP4 genes provides us with only the tip of the iceberg regarding rotavirus diversity.
Plasma and Liver Hepatitis C Virus Variability in Patients Coinfected with Human Immunodeficiency Virus
Authors: Jouvencel Anne-Christine , Neau Didier , Faure Muriel , Neau Martine , Martinaud Christophe , Legrand Elisabeth , Trimoulet Pascale , Garrigue Isabelle , Le Bail Brigitte , Bioulac-Sage Paulette , Dupon Michel , Ragnaud Jean-Marie , Fleury Herve , Lafon Marie-Edith
Published: May 2006

Liver and plasma hepatitis C virus (HCV) variability was compared by E2 cloning and sequencing in three patients coinfected with HCV and human immunodeficiency virus (HIV) before and after interferon treatment and in three patients solely infected with HCV. The plasma and liver samples contained unique sequences. In the patients coinfected with HIV, accumulated random mutations produced mostly nonsynonymous substitutions in contrast to the reduced HCV genetic variability seen after treatment.
Development and Evaluation of a Loop-Mediated Isothermal Amplification Method for Rapid Diagnosis of
Bordetella pertussis
Infection
Authors: Kamachi Kazunari , Toyoizumi-Ajisaka Hiromi , Toda Kohei , Soeung Sann Chan , Sarath Svay , Nareth Ya , Horiuchi Yoshinobu , Kojima Kazunobu , Takahashi Motohide , Arakawa Yoshichika
Published: May 2006

We developed a loop-mediated isothermal amplification (LAMP) method to detect
Bordetella pertussis
infection. This LAMP assay detected
B. pertussis
with high sensitivity, but not other
Bordetella
species. Among nasopharyngeal swab samples from subjects with suspected pertussis, LAMP results showed a high level of agreement with results of conventional PCR. This method is a rapid, sensitive, and specific method for diagnosis of
B. pertussis
infection even in clinical laboratories with no specific equipment.
Listeriosis Due to Infection with a Catalase-Negative Strain of
Listeria monocytogenes
Authors: Cepeda J. A. , Millar M. , Sheridan E. A. , Warwick S. , Raftery M. , Bean D. C. , Wareham D. W.
Published: May 2006

A strain of
Listeria monocytogenes
recovered from blood and cerebrospinal fluid had no detectable catalase activity, a characteristic used for primary identification. The sporadic occurrence of pathogenic catalase-negative strains highlights the need for a reconsideration of diagnostic criteria and questions the role of catalase in the pathogenesis of listeria infection.
Photolysis of a carbohydrate nitroolefin
Authors: Howarth G. B. , Lance D. G. , Szarek W. A. , Jones J. K. N.
Published: May 2006

Irradiation of an acetone solution of cis-6,7,8-trideoxy-1,2:3,4-di-O-isopropylidene-7-C-nitro-α-D-galacto-oct-6-enose (4) with ultraviolet light gives a complex mixture from which the three major products have been isolated: the trans isomer of the nitroolefin 4, cis-6,8-dideoxy-1,2:3,4-di-O-isopropylidene-α-D-galacto-oct-5-enos-7-ulose (5), and the trans isomer of 5. The structures of the compounds were established by spectroscopic methods. Signal assignments in the nuclear magnetic resonance spectra have been made by spin decoupling.
Stereoselective synthesis of (±)-eremophil-3,11-diene and related compounds. Concerning the structure of eremophilene
Authors: Piers Edward , Keziere Robert J.
Published: May 2006

An efficient, stereoselective synthesis of (±)-eremophil-3,11-diene (3) is described. The key step of the synthetic sequence involves the conjugate addition of lithium dimethylcopper to the octalone 7, which produces (±)-eremophil-11-en-3-one (12) in good yield. The latter is converted, via the tosylhydrazone derivative 13, into compound 3. Comparison of 3 with eremophilene indicates that the initial structural proposal for the latter sesquiterpene is in error. Evidence is presented which demonstrates that eremophilene is correctly represented by structure 4.
Spectres Raman de N2H4 et N2D4 à l'état cristallin
Authors: Guay M. , Savoie R.
Published: May 2006

Raman spectra of crystalline N2H4 and N2D4 have been recorded at various temperatures between −70 and −195 °C. The splitting of the internal modes, the large number of active lattice vibrations, and the apparent non-coincidence of infrared and Raman bands cannot be explained on the basis of the crystal structures obtained from X-ray and neutron-diffraction studies. The results suggest instead a monoclinic unit cell described by one of the C2h space groups and containing four molecules located in general positions.
Studies of stereochemical influences upon anti-histaminic activity. The synthesis, configuration, and anti-histaminic properties of some isomeric aminobutenes
Authors: Casy A. F. , Parulkar A. P.
Published: May 2006

The acid-catalyzed dehydration of 4-dimethylamino-2-p-methoxyphenyl-1-phenylbutan-2-ol yields all four possible 4-amino-1,2-diarylbutenes. Pure samples of each isomer have been isolated, double bond positions and configurations being established from proton magnetic resonance and ultraviolet spectroscopic data. A stereoselective route to cis aminobut-1-enes has been further investigated. The anti-histaminic properties of the reported butenes together with some related compounds are given and structural influences upon activity discussed.
Biosynthesis of aristolochic acid
Authors: Comer F. , Tiwari H. P. , Spenser I. D.
Published: May 2006

The biosynthesis of aristolochic acid-1 (1) was studied in Aristolochia sipho. Tyrosine, dopa, dopamine, and noradrenaline serve as specific precursors. The nitro group of aristolochic acid is derived from the amino group of tyrosine. The aristolochic acids are yet another group of natural products related to norlaudanosoline.
Heats of mixing and dielectric constants of some partially miscible liquid pairs
Authors: Campbell A. N. , Kartzmark E. M.
Published: May 2006

The physical properties mentioned in the title have been determined for the six systems: (a) aniline–hexane, (b) methanol–cyclohexane, (c) methanol–carbon disulfide, (d) acetic anhydride–carbon disulfide, (e) acetic anhydride–cyclohexane, and (f) triethylamine–water, over the complete range of composition. All six systems are partially miscible, above or below a critical solution temperature (c.s.t.).From the experimental data, the partial molal heats of mixing have been calculated, using the Redlich and Kister equations. The enthalpy of hydrogen bonding in the triethylamine–water compound appears to be about −1.33 kcal per hydrogen bond.The orientation polarization, according to the Syrkin formula, appears always to exhibit negative deviation from ideality, at least over part of the concentration range.
Abstraction of hydrogen from hydrogen sulfide by methyl radicals
Authors: Gray Peter , Herod A. A. , Leyshon L. J.
Published: May 2006

The methyl radical attack on H2S has been investigated briefly using azomethane as the radical source. The results indicate that the previous rate-constants for the abstraction reaction are too high and that CF3 radicals may react with H2S faster than CH3 radicals.
Reaction of 6,7-dimethoxy-3-isochromanone with hydrazine
Authors: Rosen Gerald , Popp Frank D.
Published: May 2006

The reaction of the title compound with hydrazine resulted in the formation of the hydroxy hydrazide 5. Alkylation of 5 took place on both oxygen and nitrogen. Compound 5 can be reconverted to the title compound or to the corresponding isoquinolone.
Low temperature Raman spectrum of rhombic sulfur
Authors: Anderson A. , Loh Y. T.
Published: May 2006

Raman spectra of polycrystalline samples of rhombic sulfur have been recorded at 100 and 300 °K, with excitation by the 5145 Å line of an argon ion laser. Spectra of sulfur solutions in carbon disulfide and bromoform were also obtained to aid in assignments. Experimental confirmation is presented of the frequencies of two intramolecular fundamental vibrations, suggested from normal coordinate analysis (one at very low frequency, the other inactive in both Raman and infrared for the free molecule). The spectra are analyzed in terms of the static and correlation crystal field perturbations, and for all except the weakest bands, substantial agreement is obtained. It is concluded that the effects of the two types of interaction are comparable in magnitude, and that a correct analysis must take account of the full symmetry of the unit cell.
Purine analogues. I. The status of Hückel molecular orbital calculations as predictors of proton shifts, basic strengths, and reactivity
Authors: Lynch Brian M. , Robertson Allan J. , Webb John G. K.
Published: May 2006

A detailed series of molecular orbital calculations based on the HMO method has been made for the various possible ionic species of purine, pyrazolo(3,4-d)pyrimidine, v-triazolo(4,5-d)pyrimidine, and pyrazolo(3,4-b)pyridine. π-Electron densities and localization and delocalization energies for nucleophilic substitution have been derived.The results are compared with the observed proton chemical shifts in the conjugate acids of these molecules, with the relative rates of nucleophilic piperidinodehalogenations in the neutral molecules, and with the ionization constants.It is concluded that it is possible to reconcile the calculations with experimental results for the various positions within a six-membered ring, but that positions in six- and five-membered rings cannot be directly compared. The electron densities seem to be of little value in correlating the observed ionization patterns of purines and their analogues.
Isolation and characterization of (+)-sesamin and β-cyclopyrethrosin from pyrethrum flowers
Authors: Doskotch Raymond W. , El-Feraly Farouk S.
Published: May 2006

Two compounds isolated from the alcoholic extract of pyrethrum flowers (Chrysanthemumcinerariaefolium Visiani) have been characterized as the lignan, (+)-sesamin (2) by physical methods and by direct comparison with a known sample and the sesquiterpene, β-cyclopyrethrosin (3) by physical methods and conversion to the known ketone 6.
Hydrogenolysis of carbohydrate acetals, ketals, and cyclic orthoesters with lithium aluminium hydride – aluminium trichloride
Authors: Bhattacharjee S. S. , Gorin P. A. J.
Published: May 2006

The reduction of hexofuranose and hexopyranose acetals with LiAlH4–AlCl3 (1:1, probably AlH2Cl) to the corresponding ethers proceeds in similar fashion as that of simple acetals and ketals (Scheme I) (refs. 1–7). Certain O-methyl and O-benzyl derivatives, not readily obtainable otherwise, are conveniently synthesized from appropriate acetals in this way. Cyclic orthoesters of glucofuranose may be selectively reduced to acetals; the steric course of such reduction has been shown unequivocally in the case of orthoformates (Scheme II). Of several cleavable groups, the ease of hydrogenolysis is (a) cyclic orthoester > isopropylidene ketal, cyclohexylidene ketal > benzylidene acetal > ethylidene acetal > formal and (b) 5,6-O-linked or 3,5-O-linked acetal or ketal > 1,2-O-linked acetal or ketal.
Identification of di-O-, tri-O-, and tetra-O-methylmannoses by gas–liquid chromatography
Authors: Bhattacharjee S. S. , Gorin P. A. J.
Published: May 2006

Some di-O- and tri-O-methylmannoses which are unknown or difficult to prepare have been synthesized. These and the other isomers, which can arise from methylation–fragmentation analyses of mannofuranose- and mannopyranose-containing polysaccharides can be used as gas–liquid chromatographic (g.l.c.) standards. A system has been devised in which methylation fragments are fractionated on a cellulose column into di-O-, tri-O-, and tetra-O-methylmannose fractions, which are then analyzed individually by g.l.c. following conversion to suitable derivatives.
Infrared studies of water in crystalline hydrates: gypsum, CaSO4•2H2O
Authors: Seidl V. , Knop Osvald , Falk Michael
Published: May 2006

Infrared spectra of partially deuterated hydrates yield the fundamental frequencies of isotopically dilute H2O, D2O, and HDO molecules. Isotopic dilution eliminates vibrational coupling and allows the determination of the total number of crystallographically distinct water molecules in the crystal. It also yields the number of distinct symmetric (C2v) and asymmetric (Cs) water molecules. The results for gypsum show that all the water molecules are equivalent and that they are asymmetric, in agreement with crystallographic results. The extent of asymmetry is measured by the difference between the two OH stretching frequencies of HDO molecules, which is 90 cm−1. This corresponds to an estimated difference of 0.02 Å in the [Formula: see text] distances of the two hydrogen bonds. The spectra of partially deuterated gypsum show clearly that spectral features previously explained by the presence of two sets of distinct water molecules or by proton tunnelling, are in fact due to vibrational coupling.
Oxidations involving silver. II. The oxidation of alcohols and aldehydes with silver(II) picolinate
Authors: Clarke T. G. , Hampson N. A. , Lee J. B. , Morley J. R. , Scanlon B.
Published: May 2006

The oxidation of alcohols by argentic picolinate has been studied and has been shown to give high yields of aldehyde and ketone. Examination of the oxidation of aldehydes shows that smooth conversion to the acid occurs in most cases, but in some cases, an anomalous reaction occurs, which probably involves attack upon the aromatic ring of substituted benzaldehydes. The oxidation of aldehydes occurs much more slowly than alcohol-oxidation under similar conditions.
Isomer ratios for the 44Ca(p,n)44Scm,g and 85Rb(p,n)85Srm,g reactions
Authors: Sachdev D. R. , Yaffe L.
Published: May 2006

Isomeric cross-section ratios for the 44Ca(p,n)44Scm,g and 85Rb(p,n)85Srm,g reactions have been measured over a proton energy range of 6–85 and 6–27 MeV, respectively. Experimental results are compared with calculations based on the Vandenbosch–Huizenga formalism (1, 2), while spin-cutoff parameter values were obtained from various models. For the isomeric pair of 44Scm,g, the parameters required to obtain a good fit with the experimental results are in agreement with those of Keedy etal. (6). On the other hand, the experimental results for the 85Srm,g isomeric pair are unusually high compared with the calculated isomer ratios. Half-lives of 44Scg and 85Srm were redetermined to be 4.05 ± 0.03 h and 68.0 ± 0.2 min, respectively.
Laboratory studies of electron attachment and detachment processes of aeronomic interest
Authors: Phelps A. V.
Published: May 2006

Techniques for the study of electron attachment and detachment are reviewed. The rate coefficients for the various processes of aeronomic interest are then discussed. The rates of three-body and dissociative attachment by thermal electrons have been successfully determined by swarm techniques and by high frequency studies of electrons produced by high energy particles and by photoionization. Collisional and associative detachment rates for thermal energy negative ions have been measured using the swarm and flowing afterglow techniques. Radiative attachment rates for some atmospheric negative ions have been calculated from measurements of photodetachment cross sections using crossed photon and ion beam techniques. Electron beam studies and measurements of ion kinetic energy have provided much useful information regarding the dissociative attachment process and the structure of molecular negative ions. Rate coefficients for low energy processes such as the three-body attachment to O2, the radiative attachment to O, and the associative detachment of O− in collisions with various atmospheric gases are reasonably well known. Other possibly important low energy processes, such as dissociative attachment to O3, radiative attachment to O2, and the associative detachment of O2− are less well known.
Associative-detachment reactions of O− and O2− by O2(1Δg)
Authors: Fehsenfeld F. C. , Albritton D. L. , Burt J. A. , Schiff H. I.
Published: May 2006

The flowing afterglow technique has been used to study the electron detachment reactions[Formula: see text]The rates of these reactions are sufficiently fast to make them important processes in D region ionospheric chemistry.
Comments
Authors: Niles F. E.
Published: May 2006

not available
Aeronomically important transition probability data
Authors: Nicholls R. W.
Published: May 2006

Since the 1963 I.A.G.A. conference at Berkeley our knowledge of radiative transitions which are aeronomically important has been extended particularly into the vacuum ultraviolet region of the spectrum. A brief review is made of the newly established important radiative transitions. Recent experimental and theoretical work on radiative transitions which have aeronomical applications is discussed.
Comments and Summary
Authors: Peterson J. R.
Published: May 2006

not available
Chemistry of the aminochromes. Part XI. Studies on 2-methylaminochromes
Authors: Hutzinger O. , Heacock R. A.
Published: May 2006

2-Methyladrenochrome and 1-ethyl-2-methylnoradrenochrome have been prepared by oxidation of 3,4-dihydroxyephedrine and 3,4-dihydroxyhomoephedrine with silver oxide. The corresponding 7-iodoaminochromes were obtained when the oxidations were carried out with potassium iodate. The expected 3,5,6-triacetoxyindoles were formed by treatment of these aminochromes with acetic anhydride and pyridine and the corresponding 5,6-dihydroxyindoles (isolated as their diacetyl derivatives) were obtained by reduction of the aminochromes with sodium borohydride or sodium hydrosulfite. An improved procedure for the synthesis of 3,4-dihydroxyephedrine (α-methyladrenaline) is also described.
Nuclear magnetic relaxation of 1,2-dichloroethane in deuterated benzene and carbon disulfide solution at 20 °C
Authors: Bock E. , Tomchuk E.
Published: May 2006

The molecular rotational relaxation time of the 1,2-dichloroethane molecule in deuterated benzene and carbon disulfide solution was determined by pulsed nuclear magnetic resonance techniques. It was found that the rotational relaxation time, τr, in infinitely dilute deuterated benzene solution and in infinitely dilute carbon disulfide solution was 1.3 × 10−12 and 0.6 × 10−12 s, respectively. Both values are in fair agreement with the dielectric molecular relaxation time for 1,2-dichloroethane in dilute benzene, p-xylene, and n-hexane solution reported by Chitoku and Higasi (1).
Characterization and photolysis of octacyanomolybdic(IV) acid: isolation of a red photoproduct
Authors: Mitra R. P. , Sharma B. K. , Mohan Hari
Published: May 2006

pH and conductometric titration of aqueous octacyanomolybdic acid shows that it has 4 strong H+ ions per Mo(IV). Photolysis of an ice-cold solution of the acid gives a red anion, [Mo(CN)7H2O]3−, which has been isolated as a silver salt. When the corresponding (red) acid is titrated, 3 strong H+ ions are first neutralized and then one more equivalent of the base is consumed in a slow substitution reaction to give a yellow anion, [Mo(CN)7OH]4−.
Stéréochimie de l'addition de réactifs de Grignard sur la t-butyl-2 cyclohexanone
Authors: Richer Jean-Claude , Eugène Denis
Published: May 2006

not available
Influence of Lewis acids on the Diels–Alder reaction. Part I. An improved synthesis of 7-azanorbornadiene, 3-azaquadricyclane, and azepine derivatives
Authors: Bansal R. C. , McCulloch A. W. , McInnes A. G.
Published: May 2006

Depending on the experimental conditions the AlCl3-promoted reaction of 1-carbomethoxypyrrole and dimethyl acetylenedicarboxylate yields 2,3,7-tricarbomethoxy-7-azanorbornadiene, either in almost quantitative yield or together with dimethyl 1-carbomethoxy-2-pyrrolyl maleate and fumarate. The azanorbornadiene has been quantitatively converted to 1,4,5-tricarbomethoxyazepine via the corresponding 3-azaquadricyclane. The proton magnetic resonance spectra were analyzed with the aid of the Laocoon II program.
Alkaloids of Lycopodiumalopecuroides. Part 2. Alopecurine, a new type of Lycopodium alkaloid
Authors: Ayer W. A. , Altenkirk B. , Masaki N. , Valverde-Lopez S.
Published: May 2006

Alopecurine, a pentacyclic Lycopodium alkaloid, has been shown to possess structure 1. The structure, including the absolute stereochemistry, was established by X-ray analysis of debenzoylalopecurine hydrobromide, and further confirmed by X-ray analysis of alopecurine methobromide. Some chemical and spectroscopic properties of alopecurine are described. The isolation of four alkaloids in addition to those already reported from L. alopecuroides is described. These alkaloids include the known compound fawcettidine and three new bases, acetyldebenzoylalopecurine, alolycopine, and lycopecurine.
Tertiary phosphite–alkyl halide reactions in acetonitrile
Authors: Goodell Lane J. , Yoke John T.
Published: May 2006

Olefin elimination does not occur during the interaction of ca. 0.2 M triisopropyl phosphite and isopropyl iodide (and of other simple tertiary phosphite–alkyl halide mixtures) in acetonitrile, contrary to a previous report. At and below 50°, the Arbuzov reaction does occur very slowly in these systems. The reaction of trimethyl phosphite and n-butyl iodide in acetonitrile gives a larger yield of dimethyl methylphosphonate than of dimethyl n-butylphosphonate.
Thermal reactions of O− ions with saturated hydrocarbon molecules
Authors: Bohme D. K. , Fehsenfeld F. C.
Published: May 2006

The thermal energy reactions of O− ions with saturated, hydrocarbon molecules have been investigated in a flowing afterglow of pure oxygen and a mixture of helium and oxygen. Hydrogen atom abstraction was found to be the dominant reaction channel. The reaction probability was found to increase for the higher members of the homologous series. The further reaction of the product OH− ions with saturated hydrocarbon molecules was not observed. This result was used to estimate an upper limit to the electron affinity of the free radicals CH3, C2H5, C3H7, and C4H9.
Photolysis of thiophene vapor
Authors: Wiebe H. A. , Heicklen Julian
Published: May 2006

Thiophene vapor was photoexcited with 2139 and 2288 Å radiation as well as by mercury sensitization at 2537 Å. Experiments were done at 25, 200, and 305 °C at various pressures and light intensities as well as in the presence of CO2, C2H4, butenes, and O2. In all cases the products were C2H2, CH2CCH2, CH3CCH, CS2, CH2CHCCH, and polymer. When O2 was present CO2, COS, SO2, and CO were also produced. The product quantum yields dropped as the pressure was raised. A mechanism was deduced and is given by the lettered reactions in the text. The initially formed excited state, Th* (where Th stands for thiophene), as well as the excited intermediate leading to CH2CCH2 production, I*, decomposed at a rate dependent only on the total energy content, regardless of whether thermal or photolytic. The efficiencies for energy removal from both Th* and I* decrease along the series: thiophene, C2H4, CO2, O2. Appropriate rate constant ratios for all the gases were obtained and are listed in Table IX. Experiments in the presence of olefins showed that sulfur atoms were not intermediates. The experiments with O2 further eliminated a number of possibilities. The hydrocarbones are all produced in primary processes with additional CH2CHCCH and C2H2 coming respectively from the postulated intermediates •CHCHCHCHS• and C2H2S. Along with the C3 hydrocarbons, excited CS species are produced. They can either react with the above intermediates to produce CS2 or be deactivated to eventually form polymer (or oxidation products in the presence of O2).
Reaction of methyl radicals with cis-butene-2
Authors: Yokoyama Nobuo , Brinton R. K.
Published: May 2006

Methyl radicals generated by di-t-butylperoxide pyrolysis interact at comparable rates with cis-butene-2 in the gas phase by both addition and hydrogen atom abstraction. The determination of the rate of these reactions was simplified by the addition of a large concentration of acetaldehyde to the system. The additive, a source of low activation energy abstractable hydrogen atoms, was effective in suppressing polymerization reactions, and in addition, maintained a high steady state methyl radical concentration as a result of the carbonyl radical decomposition. The rate constants, k5 and k6 for the reactions [5] and [6], were determined to be 4.5 × 1010exp (−7000/RT)and 1.8 × 1010exp (−7300/RT)[Formula: see text]cm3 mole−1 s−1, respectively, over the temperature range 126–163 °C. The butenyl radical formed in reaction [6] isomerizes much faster than its interaction with other species in the system, and the distribution of the various conformations is similar to the equilibrium distribution of the butenes at a similar temperature.
Thermal decomposition of barium perchlorate
Authors: Acheson R. J. , Jacobs P. W. M.
Published: May 2006

The thermal decomposition of anhydrous barium perchlorate to barium chloride and oxygen has been studied by pressure measurements, or by weight loss, in vacuo, under the accumulated gaseous products (0–3 Torr oxygen), under dry air or nitrogen, and mixed with added barium chloride. The plots of fractional decomposition (α) against time (t) are complex, as would be expected for a reaction proceeding via unstable intermediates. The most pronounced features of the α(t) curves are an initial acceleratory period, which is succeeded by an approximately linear period and then, after a sharp break (reduction in rate), by a deceleratory period which conforms to the contracting-volume kinetic law. The latter stage is associated with the decomposition of barium chlorate and has an activation energy of 59 kcal/mole. The first two stages comprise the decomposition of perchlorate to chlorate with the approximate stoichiometry 3ClO4− = 2ClO3− + Cl− + 3O2. A chain reaction sequence, which involves O atoms as chain carriers, is proposed for these stages. The effect of the removal of products, of increasing the ambient pressure of inert gas, and of the addition of barium chloride, can all be explained on this model.
Nuclear magnetic resonance studies. XVI. Oxygen-17 shieldings of some substituted acetophenones
Authors: Sardella D. J. , Stothers J. B.
Published: May 2006

The 17O spectra of some ortho- and para-substituted acetophenones were determined to examine the effect of substituent polarity and steric hindrance on the acetyl oxygen shieldings. The results are compatible with proposals previously advanced on the basis of the 13C shielding data for these compounds.
N-Chlorination of secondary amides. II. Effects of substituents on rates of N-chlorination
Authors: Thomm E. W. C. W. , Wayman M.
Published: May 2006

Various secondary amides have been N-chlorinated, at high and at low pH. The reactivity of the chlorinating reagents with all the amides investigated was found to have the sequence[Formula: see text]The substituent groups R1 and R2 of the amide [Formula: see text] were found to have large effects on the rate of chlorination. With the three molecular chlorinating agents, the reactivity of the amides was found to be in the order[Formula: see text]With hypochlorite ion the reverse order of reactivity was observed. These results are discussed and reaction mechanisms proposed. It is proposed that, when a hypochlorite ion is a chlorinating agent, the primary reaction is hydrogen bond formation between the amido hydrogen and the hypochlorite oxygen atom, but that the donation of electrons from the amido N to the Cl atom is the primary reaction with the molecular chlorinating agents.
Reactions of diphos and diars with iron carbonyls: a reinvestigation
Authors: Cullen W. R. , Harbourne D. A.
Published: May 2006

The bidentate ligands diars (1) and diphos (2) react with iron carbonyls to give the previously known diarsFe(CO)3, diphosFe(CO)3, diphosFe2(CO)8, and the new complex diarsFe2(CO)8. The reactions of diars also yield compounds in which the ligand has been modified. DiarsFe(CO)3 reacts readily with chloroform to give a new paramagnetic iron carbonyl complex.
Préparation et caractérisation de polymères-modèle à structure en étoile, par copolymérisation séquencée anionique
Authors: Worsfold Denis J. , Zilliox Jean-Georges , Rempp Paul
Published: May 2006

Star-shaped polystyrene samples have been synthesized by anionic block-copolymerization of styrene and divinylbenzene (DVB), the proportion of the latter monomer being of the order of a few molecules per living end. Vacuum technique was used and benzene was chosen as solvent. The samples were found almost free of linear polystyrene, and of very low polydispersity. The number of branches was found to be a function of the overall concentration, of the amount of DVB, and of the molecular weight of the linear precursor. The results obtained with the meta and the para isomers did not differ significantly, as far as the products themselves are concerned. However, spectroscopic investigations carried out during reaction showed that the reactivity of the 2 double bonds of the para isomer differ significantly, whereas this is not the case with the meta isomer.
Comparison of proton magnetic resonance spectra of cell-wall mannans and galactomannans of selected yeasts with their chemical structures
Authors: Gorin P. A. J. , Spencer J. F. T. , Magus R. J.
Published: May 2006

Yeasts can often be identified with the aid of the distinctive proton magnetic resonance (p.m.r.) spectra of their cell-wall mannans or galactomannans. Some of the polysaccharides, such as the galactomannan of Torulopsisgropengiesseri and the mannan of Saccharomycesrouxii give p.m.r. spectra with only slight differences and have closely related chemical structures in terms of main chains and side chains. Other spectrally similar polysaccharides with related chemical structures have also been found. These are firstly the galactomannans of Trichosporonfermentans and Candidalipolytica and secondly the mannose-containing polysaccharides of Torulopsisbombi (Torulopsis species PRL 319-67), Torulopsis magnoliae and Torulopsisapicola (Hajsig strain). The mannans of Candidacatenulata and Endomycopsisfibuliger give p.m.r. spectra with a lesser degree of similarity, but have markedly different chemical structures. These results show that polysaccharides with similar p.m.r. spectra have related chemical structures and may therefore arise from phylogenetically related yeasts.
Structure of didehydrochelidonine
Authors: Benn M. H. , Mitchell R. E.
Published: May 2006

Gadamer's didehydrochelidonine is the internal carbinolamine ether 2c. The formation of this compound, as also its reduction back to the parent alkaloid, provides chemical proof that the relative stereochemistry of chelidonine is, as previously deduced from spectroscopic studies, that given in 1.
Pyrazolines X. Kinetics for the pyrolysis of some deuterated 1-pyrazolines in solution
Authors: McGreer Donald E. , Masters Ian M. E.
Published: May 2006

The kinetics and product distribution have been measured for the pyrolysis of 3-methyl-3-carbo-methoxy-1-pyrazoline (1) and its 4,4-d2 and 5,5-d2 analogues in tetralin, n-butyl phthalate, nitrobenzene, and formamide. The isotope effect kH/kD for 1-5,5-d2 of 1.22 and for 1-4,4-d2 of 1.36 is consistent with a mechanism involving migration of the C-4 hydrogen concerted with loss of nitrogen.
Mechanism of initiation in the thermal polymerization of styrene. Kinetic deuterium isotope effects in the initiation step of the thermal polymerization of some deuterated styrenes
Authors: Kopecky Karl R. , Evani Syamalarao
Published: May 2006

A convenient synthesis of 2,6-dideuteriostyrene starts with N,N-dimethyl-(1-phenylethyl)-amine which is deuterated in the 2 and 6 positions by a series of exchanges using n-butyllithium followed by deuterium oxide. The deuterium isotope effects at 70° on the rates of the thermal polymerization, [Formula: see text], of 2,6-dideuterio-, α-deuterio-, and β,β-dideuteriostyrene are 1.29, 1.00, and 0.78, respectively. The deuterium isotope effects at 70° on the 2,2′-azobis-(2-methylpropionitrile) initiated rates of polymerization,[Formula: see text], are 0.96, 0.86, and 0.81, respectively. From these values the deuterium isotope effects on the rates of initiation of the thermal polymerization, k1H/k1D, are calculated to be 1.80, 1.31, and 0.92, respectively. At 147° the presence of 1.5% potassium t-butoxide decreases the rate of the thermal polymerization of neat styrene by a factor of 17, and results in the formation of 1-phenyltetralin as the greatly predominant dimer. The results support the suggestion that the thermal polymerization of styrene is initiated by hydrogen transfer from 1-phenyl-1,2,3,9-tetrahydronaphthalene, formed by a concerted dimerization of two molecules of styrene, to a third molecule of styrene.
Bisglycosidylamines, a new class of amino sugars
Authors: Baer Hans H. , Rajabalee Farouk
Published: May 2006

Nucleophilic addition of methyl 2-amino-4,6-O-benzylidene-2,3-dideoxy-3-nitro-α-D-glucopyranoside (2) to methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-α-D-erythro-hex-2-enopyranoside (1) furnished bis(methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-α-D-glucopyranosid -2-yl)amine (3). The debenzylidenated product (4) gave a tetraacetate (5) and, on catalytic hydrogenation, it afforded bis(methyl 3-amino-2,3-dideoxy-α-D-glucopyranosid-2-yl)amine which crystallized as a trihydrochloride (6). Acetylation of 6 gave a di-N-acetyltetra-O-acetyl derivative (7); the secondary amino group remained free, presumably owing to steric hindrance.
Studies related to Bute Inlet wax. The identity of norphytane, pristane, and bute hydrocarbon
Authors: Jain Tikam C. , Striha Robert J.
Published: May 2006

Spectral and gas–liquid chromatographic evidence is presented to confirm the identity of pristane with norphytane and bute hydrocarbon.
Une nouvelle méthode de synthèse des peptides de la cystine
Authors: Marinier Bernard , Bérubé Michèle
Published: May 2006

The synthesis of oxidized glutathione from djenkolic acid is used to expose a new method of preparation of cystine peptides. The brominative oxidation of a djenkolic acid peptide is the essential and original step of this method.
An analytical method for determining rate constants using a periodical irradiation technique
Authors: Kawakami W. , Isbin H. S.
Published: May 2006

A new analytical method is presented for the determination of rate constants using a periodical irradiation technique. This method is applicable to reactions which have both a first and a second order termination for the chain radical concentration, and is illustrated for the radiolysis of aqueous solutions of chloral hydrate by 137Cs γ rays. The apparent rate constant of first order termination, and the mean chain life time of the chain radical were determined to be 1.10 s−1, and 0.25 s for 400 rad/min, at 22 °C, respectively.
Salting-in and salting-out of polar nonelectrolytes
Authors: Desnoyers J. E. , Ichhaporia F. M.
Published: May 2006

The solubility of toluene and benzaldehyde was measured in NaBr and (n-Pr)4NBr aqueous solutions at 25 °C, and the solubility of benzoic acid and nitrobenzene was measured in the same systems at 10, 25, and 40 °C. The apparent molal volumes of the four nonelectrolytes were also determined from the densities of the saturated aqueous solutions.The volumes of mixing of the nonelectrolytes in water are all negative but become less so as their polarity increases. With the exception of benzoic acid, the salting-out by NaBr and the salting-in by (n-Pr)4NBr both decrease with increasing polarity of the nonelectrolytes. Both salting effects increase with temperature. These trends can be explained with existing theories of salting-out and salting-in.
Electrochemiluminescence of carbazole
Authors: Santhanam K. S. V. , O'Brien R. N. , Kirk A. D.
Published: May 2006

not available
Phytochemical investigation of Manitoba plants. I. A new indole alkaloid and associated alkaloids from Phalaris arundinacea
Authors: Audette R. C. S. , Vijayanagar H. M. , Bolan J. , Clark K. W.
Published: May 2006

Hordenine, gramine, and an unknown compound assigned the structure of 2,9-dimethyl-6-methoxy-1,2,3,4-tetrahydro-β-carboline and n-octacosanol were isolated from Phalaris arundinacea Var. Ottawa Synthetic C grown in Manitoba. The compounds were separated by a counter current distribution method followed by column chromatography on Woelm basic alumina, and were characterized by the use of infrared, ultraviolet, mass, and nuclear magnetic resonance spectroscopy.
Thermolysis of bicyclo[4.2.2]deca-2,4,7,9-tetraene
Authors: Seidner R. T. , Nakatsuka N. , Masamune S.
Published: May 2006

This title compound has been shown to undergo thermal isomerizations, intramolecular Diels–Alder reaction, and rearrangement to cis-9,10-dihydronaphthalene. Evidence presented establishes that tetracyclo[4.4.0.0.2,1005,7]deca-3,8-diene is the intermediate of these reactions.
On the origin of peaks in the potentiostatic and potentiodynamic oxidation curves of ethylene glycol
Authors: Vijh Ashok K.
Published: May 2006

The peaks observed in the potentiostatic and potentiodynamic oxidation curves of ethylene glycol have been shown to be mainly kinetic inhibition inflections.The manner in which this observation clarifies the significance of some previous work has been briefly pointed out.
On the mechanism of ring opening in 2-pyrone irradiations
Authors: Guthrie J. P. , McIntosh C. L. , Mayo P. De
Published: May 2006

The irradiation of 2-pyrone in benzene followed by pyrolysis gives a poor yield of cyclooctatetraene. The irradiation of 4-methoxy-6-methyl-2-pyrone in water gives cis-β-methyl glutaconic half ester and the corresponding diacid. Irradiation in benzene followed by the addition of water gives a mixture of the cis and trans glutaconic derivatives. It is believed that these substances derive from the β-lactone formed by irradiation, and support for this view is obtained from low temperature irradiations. An oligomeric intermediate (16) is suggested as a second intermediate in the irradiation in benzene, and a hemiketal (20) in the aqueous irradiation.
Kinetics of the hydrolysis of thiochloroformate esters in pure water
Authors: Queen A. , Nour T. A. , Paddon-Row M. N. , Preston K.
Published: May 2006

The effects of structural changes on the rates of hydrolysis of a series of thiochloroformate esters in water have been investigated. The reactivity is enhanced by increased electron donation by the hydro carbon group. These results, the activation parameters for the hydrolysis of methyl thiochloroformate and the solvent deuterium isotope effect, are shown to be consistent with the operation of the SN1 mechanism.
Effect of pressure on the rate of solvolysis of t-butyl chloride in ethanol-water mixtures
Authors: Baliga B. T. , Whalley E.
Published: May 2006

The effect of pressure on the rate of spontaneous solvolysis of t-butyl chloride in ethanol–water mixtures in the range 0 to 40 %v/v ethanol at 0 °C has been measured up to a maximum pressure of 3 kbar. The results have been examined from several points of view and the conclusions are briefly described in the summary.
Crystal structure of triclinic rubidium dichromate, Rb2Cr2O7
Authors: Panagiotopoulos N. Ch. , Brown I. D.
Published: May 2006

The crystal structure of triclinic rubidium dichromate has been determined by single crystal X-ray diffraction. The crystal belongs to space group [Formula: see text] with a = 13.554, b = 7.640, c = 7.735 Å, α = 93.64°, β = 98.52°, γ = 88.80° and has four Rb2Cr2O7 units in the unit cell. The final weighted agreement index after refinement by least-squares analysis is 0.058. The configuration of the dichromate ions is similar to that found in most other dichromate structures (Cr—O (bridging) = 1.78 Å, Cr—O (terminal) = 1.62 Å). The two non-equivalent Cr—O—Cr angles are 123 and 137°. The rubidium ions are surrounded by either 8 or 9 oxygen atoms at distances ranging from 2.86 to 3.31 Å. The structure of triclinic Rb2Cr2O7 is similar, but not identical, to that of triclinic K2Cr2O7.
Hemolytic decomposition of di-sec-butyl peroxide
Authors: Hiatt R. , Szilagyi Sandor
Published: May 2006

Rates and products have been determined for the thermal decomposition of sec-butyl peroxide at 110–150 °C in several solvents.The decomposition was shown to be unimolecular with energies of activation in toluene, benzene, and cyclohexane of 35.5 ± 1.0, 33.2 ± 1.0, 33.8 ± 1.0 kcal/mole respectively. The activation energy of thermal decomposition for the deuterated peroxide was found to be 37.2 + 1.0 kcal/mole in toluene.About 70–80% of the products could be explained by known reactions of free alkoxy radicals, and very little, if any, disproportionation of two sec-butoxy radicals in the solvent cage could be detected.The other 20–30% of the peroxide yielded H2 and methyl ethyl ketone. The yield of H2 was unaffected by the nature or the viscosity of the solvent, but H2 was not formed when s-Bu2O2 was photolyzed in toluene at 35 °C nor when the peroxide was thermally decomposed in the gas phase.α,α′-Dideutero-sec-butyl peroxide was prepared and decomposed in toluene at 110–150 °C. The yield of D2 was about the same as the yield of H2 from s-Bu2O2, but the rate of decomposition (at 135 °C) was only 1/1.55 as fast.Mechanisms for hydrogen production are discussed, but none satisfactorily explains all the evidence.