bluuebunny/crossref_metadata_2025 huggingface dataset:
A Single Monooxygenase, Ese, Is Involved in the Metabolism of the Organochlorides Endosulfan and Endosulfate in an
Arthrobacter
sp
Authors: Weir Kahli M. , Sutherland Tara D. , Horne Irene , Russell Robyn J. , Oakeshott John G.
Published: May 2006

In this paper we describe isolation of a bacterium capable of degrading both isomers of the organochloride insecticide endosulfan and its toxic metabolite, endosulfate. The bacterium was isolated from a soil microbial population that was enriched with continuous pressure to use endosulfate as the sole source of sulfur. Analysis of the 16S rRNA sequence of the bacterium indicated that it was an
Arthrobacter
species. The organochloride-degrading activity was not observed in the presence of sodium sulfite as an alternative sulfur source, suggesting that the activity was part of the sulfur starvation response of the strain. A gene,
ese
, encoding an enzyme capable of degrading both isomers of endosulfan and endosulfate was isolated from this bacterium. The enzyme belongs to the two-component flavin-dependent monooxygenase family whose members require reduced flavin for activity. Nuclear magnetic resonance analyses identified the metabolite of endosulfan as endosulfan monoalcohol and the metabolite of endosulfate as endosulfan hemisulfate. The
ese
gene was located in a cluster of 10 open reading frames encoding proteins with low levels of sulfur-containing amino acids. These open reading frames were organized into two apparent divergently orientated operons and a gene encoding a putative LysR-type transcriptional regulator. The operon not containing
ese
did contain a homologue whose product exhibited 62% amino acid identity to the
ese
-encoded protein.
Coupled Photochemical and Enzymatic Mn(II) Oxidation Pathways of a Planktonic
Roseobacter
-Like Bacterium
Authors: Hansel Colleen M. , Francis Chris A.
Published: May 2006

Bacteria belonging to the
Roseobacter
clade of the α-
Proteobacteria
occupy a wide range of environmental niches and are numerically abundant in coastal waters. Here we reveal that
Roseobacter
-like bacteria may play a previously unrecognized role in the oxidation and cycling of manganese (Mn) in coastal waters. A diverse array of Mn(II)-oxidizing
Roseobacter
-like species were isolated from Elkhorn Slough, a coastal estuary adjacent to Monterey Bay in California. One isolate (designated AzwK-3b), in particular, rapidly oxidizes Mn(II) to insoluble Mn(III, IV) oxides. Interestingly, AzwK-3b is 100% identical (at the 16S rRNA gene level) to a previously described
Pfiesteria
-associated
Roseobacter
-like bacterium, which is not able to oxidize Mn(II). The rates of manganese(II) oxidation by live cultures and cell-free filtrates are substantially higher when the preparations are incubated in the presence of light. The rates of oxidation by washed cell extracts, however, are light independent. Thus, AzwK-3b invokes two Mn(II) oxidation mechanisms when it is incubated in the presence of light, in contrast to the predominantly direct enzymatic oxidation in the dark. In the presence of light, production of photochemically active metabolites is coupled with initial direct enzymatic Mn(II) oxidation, resulting in higher Mn(II) oxidation rates. Thus,
Roseobacter
-like bacteria may not only play a previously unrecognized role in Mn(II) oxidation and cycling in coastal surface waters but also induce a novel photooxidation pathway that provides an alternative means of Mn(II) oxidation in the photic zone.
Dynamics of a Pig Slurry Microbial Community during Anaerobic Storage and Management
Authors: Peu Pascal , Brugère Hubert , Pourcher Anne-Marie , Kérourédan Monique , Godon Jean-Jacques , Delgenès Jean-Philippe , Dabert Patrick
Published: May 2006

The microbial community of a pig slurry on a farm was monitored for 6 months using both molecular and cultural approaches. Sampling was carried out at all the different stages of effluent handling, from the rearing build-up to slurry spreading. Total DNA of each sample was extracted and analyzed by PCR-single-strand conformation polymorphism (SSCP) analysis using primers targeting the 16S rRNA genes from the archaeal and bacterial domains and also the
Eubacterium
-
Clostridium
,
Bacillus-Streptococcus-Lactobacillus
, and
Bacteroides-Prevotella
groups. A comparison of the SSCP profiles showed that there were rapid changes in the dominant bacterial community during the first 2 weeks of anaerobic storage and that the community was relatively stable thereafter. Several bacterial populations, identified as populations closely related to uncultured
Clostridium
and
Porphyromonas
and to
Lactobacillus
and
Streptococcus
cultured species commonly isolated from pig feces, remained present and dominant from the rearing build-up to the time of spreading. Enumeration of fecal indicators (enterococci and
Escherichia coli
) performed in parallel using cultural methods revealed the same trends. On the other hand, the archaeal community adapted slowly during pig slurry storage, and its diversity increased. A shift between two hydrogenotrophic methanogenic
Methanobrevibacter
populations from the storage pit to the pond was observed. Microorganisms present in pig slurry at the time of spreading could not be detected in soil after spreading by either molecular or cultural techniques, probably because of the detection limit inherent in the two techniques.
Two Routes of Metabolic Cross-Feeding betweenBifidobacterium adolescentisand Butyrate-Producing Anaerobes from the Human Gut
Authors: Belenguer Alvaro , Duncan Sylvia H. , Calder A. Graham , Holtrop Grietje , Louis Petra , Lobley Gerald E. , Flint Harry J.
Published: May 2006

Dietary carbohydrates have the potential to influence diverse functional groups of bacteria within the human large intestine. Of 12Bifidobacteriumstrains of human gut origin from seven species tested, four grew in pure culture on starch and nine on fructo-oligosaccharides. The potential for metabolic cross-feeding betweenBifidobacterium adolescentisand lactate-utilizing, butyrate-producingFirmicutebacteria related toEubacterium halliiandAnaerostipes caccaewas investigated in vitro.E. halliiL2-7 andA. caccaeL1-92 failed to grow on starch in pure culture, but in coculture withB. adolescentisL2-32 butyrate was formed, indicating cross-feeding of metabolites to the lactate utilizers. Studies with [13C]lactate confirmed carbon flow from lactate, via acetyl coenzyme A, to butyrate both in pure cultures ofE. halliiand in cocultures withB. adolescentis. Similar results were obtained in cocultures involvingB. adolescentisDSM 20083 with fructo-oligosaccharides as the substrate. Butyrate formation was also stimulated, however, in cocultures ofB. adolescentisL2-32 grown on starch or fructo-oligosaccharides withRoseburiasp. strain A2-183, which produces butyrate but does not utilize lactate. This is probably a consequence of the release byB. adolescentisof oligosaccharides that are available toRoseburiasp. strain A2-183. We conclude that two distinct mechanisms of metabolic cross-feeding betweenB. adolescentisand butyrate-forming bacteria may operate in gut ecosystems, one due to consumption of fermentation end products (lactate and acetate) and the other due to cross-feeding of partial breakdown products from complex substrates.
Microeukaryote Community Patterns along an O2/H2S Gradient in a Supersulfidic Anoxic Fjord (Framvaren, Norway)
Authors: Behnke Anke , Bunge John , Barger Kathryn , Breiner Hans-Werner , Alla Victoria , Stoeck Thorsten
Published: May 2006

To resolve the fine-scale architecture of anoxic protistan communities, we conducted a cultivation-independent 18S rRNA survey in the superanoxic Framvaren Fjord in Norway. We generated three clone libraries along the steep O2/H2S gradient, using the multiple-primer approach. Of 1,100 clones analyzed, 753 proved to be high-quality protistan target sequences. These sequences were grouped into 92 phylotypes, which displayed high protistan diversity in the fjord (17 major eukaryotic phyla). Only a few were closely related to known taxa. Several sequences were dissimilar to all previously described sequences and occupied a basal position in the inferred phylogenies, suggesting that the sequences recovered were derived from novel, deeply divergent eukaryotes. We detected sequence clades with evolutionary importance (for example, clades in the euglenozoa) and clades that seem to be specifically adapted to anoxic environments, challenging the hypothesis that the global dispersal of protists is uniform. Moreover, with the detection of clones affiliated with jakobid flagellates, we present evidence that primitive descendants of early eukaryotes are present in this anoxic environment. To estimate sample coverage and phylotype richness, we used parametric and nonparametric statistical methods. The results show that although our data set is one of the largest published inventories, our sample missed a substantial proportion of the protistan diversity. Nevertheless, statistical and phylogenetic analyses of the three libraries revealed the fine-scale architecture of anoxic protistan communities, which may exhibit adaptation to different environmental conditions along the O2/H2S gradient.
Identification and Localization of a
Rickettsia
sp. in
Bemisia tabaci
(Homoptera: Aleyrodidae)
Authors: Gottlieb Yuval , Ghanim Murad , Chiel Elad , Gerling Dan , Portnoy Vitaly , Steinberg Shimon , Tzuri Galil , Horowitz A. Rami , Belausov Eduard , Mozes-Daube Neta , Kontsedalov Svetlana , Gershon Moshe , Gal Shunit , Katzir Nurit , Zchori-Fein Einat
Published: May 2006

Whiteflies (Homoptera: Aleyrodidae) are sap-sucking insects that harbor “
Candidatus
Portiera aleyrodidarum,” an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. These insects are also home for a diverse facultative microbial community which may include
Hamiltonella
,
Arsenophonus
,
Fritchea
,
Wolbachia
, and
Cardinium
spp. In this study, the bacteria associated with a B biotype of the sweet potato whitefly
Bemisia tabaci
were characterized using molecular fingerprinting techniques, and a
Rickettsia
sp. was detected for the first time in this insect family.
Rickettsia
sp. distribution, transmission and localization were studied using PCR and fluorescence in situ hybridizations (FISH).
Rickettsia
was found in all 20 Israeli
B. tabaci
populations screened but not in all individuals within each population. A FISH analysis of
B. tabaci
eggs, nymphs, and adults revealed a unique concentration of
Rickettsia
around the gut and follicle cells, as well as a random distribution in the hemolymph. We postulate that the
Rickettsia
enters the oocyte together with the bacteriocytes, leaves these symbiont-housing cells when the egg is laid, multiplies and spreads throughout the egg during embryogenesis and, subsequently, disperses throughout the body of the hatching nymph, excluding the bacteriomes. Although the role
Rickettsia
plays in the biology of the whitefly is currently unknown, the vertical transmission on the one hand and the partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others.
Effects of Quaternary Ammonium Silane Coatings on Mixed Fungal and Bacterial Biofilms on Tracheoesophageal Shunt Prostheses
Authors: Oosterhof Janine J. H. , Buijssen Kevin J. D. A. , Busscher Henk J. , van der Laan Bernard F. A. M. , van der Mei Henny C.
Published: May 2006

Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyldimethyloctadecylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF, was sprayed onto the silicone rubber surface. The sprayed coating lost its stability within an hour, while the chemically bonded coating appeared stable. Upon incubation in an artificial throat model, allowing simultaneous adhesion and growth of yeast and bacteria, all coated prostheses showed significant reductions in the numbers of viable yeast (to 12% to 16%) and bacteria (to 27% to 36%) compared with those for silicone rubber controls, as confirmed using confocal laser scanning microscopy after live/dead staining of the biofilms. In situ hybridization with fluorescently labeled oligonucleotide probes showed that yeasts expressed hyphae on the untreated and Biocidal ZF-coated prostheses but not on the QAS-coated prostheses. Whether this is a result of the positive QAS coating or is due to the reduced number of bacteria is currently unknown. In summary, this is the first report on the inhibitory effects of positively charged coatings on the viability of yeasts and bacteria in mixed biofilms. Although the study initially aimed at reducing voice prosthetic biofilms, its relevance extends to all biomedical and environmental surfaces where mixed biofilms develop and present a problem.
Molecular Epidemiology of
Haemophilus influenzae
Type b Causing Vaccine Failures in the United Kingdom
Authors: Aracil Belén , Slack Mary , Pérez-Vázquez María , Román Federico , Ramsay Mary , Campos José
Published: May 2006

Haemophilus influenzae
type b (Hib) was a major cause of pediatric disease in the United Kingdom prior to the introduction of routine Hib immunization in 1992. An unexpected resurgence of cases of vaccine failure was observed with fully vaccinated children from 1999 onward. We investigated whether Hib isolates causing vaccine failures in the United Kingdom could have undergone a change in their population structure to elude the protective effect of Hib vaccine. Molecular epidemiology studies were carried out with 376 isolates from invasive infections (164 vaccine failures and 212 controls). Genetic variability was higher in controls than in vaccine failures. Of the four major clusters obtained, cluster I comprised 92.2% of the total isolates: 156 vaccine failures (95%) and 193 (91%) controls. Cluster IV was specific for vaccine failures but included only four isolates. The increased number of cases of invasive Hib in fully vaccinated children in the United Kingdom was caused by isolates belonging not to a particular or new genotype but to genotypes already circulating in the prevaccination era, before conjugate Hib vaccines were available.
Nutritional Requirements and Antibiotic Resistance Patterns ofHelicobacterSpecies in Chemically Defined Media
Authors: Testerman Traci L. , Conn P. Brian , Mobley Harry L. T. , McGee David J.
Published: May 2006

The growth of the gastric pathogenHelicobacter pyloriin the absence of serum remains challenging, and nutritional requirements have only partially been defined, while almost nothing is known about nutritional requirements of otherHelicobacterspp. Although previous data showed thatH. pylorigrows in the chemically defined medium F-12, but not in other tissue culture media examined, the specific components responsible for growth were not entirely understood. Here we describe the optimization of amino acids, metals, and sodium chloride forH. pylori. Iron, zinc, and magnesium were critical for growth; copper was not required. Optimization of sodium chloride was further beneficial. Nutritional requirements and antibiotic resistance patterns of several otherHelicobacterspp. revealed that all exceptH. felisgrew in serum-free, unsupplemented F-12. AllHelicobacterspp. were resistant to at least six antimicrobial agents when cultured in the presence of serum. However, in the absence of serum,H. pylori,H. mustelae, andH. muridarumbecame sensitive to polymyxin B and/or trimethoprim. Much of the data were obtained using a convenient ATP assay to quantify growth.H. pylorihas surprisingly few absolute requirements for growth: 9 amino acids, sodium and potassium chloride, thiamine, iron, zinc, magnesium, hypoxanthine, and pyruvate. These data suggest thatH. pyloriand otherHelicobacterspp. are not as fastidious as previously thought. The data also suggest that chemically defined media described herein could yield the growth of a wide range ofHelicobacterspp., allowing a more detailed characterization ofHelicobacterphysiology and interactions with host cells.
Multilaboratory Evaluation of Disk Diffusion Antimicrobial Susceptibility Testing of
Neisseria meningitidis
Isolates
Authors: Jorgensen James H. , Crawford Sharon A. , Fulcher Letitia C. , Glennen Anita , Harrington Susan M. , Swenson Jana , Lynfield Ruth , Murray Patrick R. , Tenover Fred C.
Published: May 2006

In 2005, the Clinical and Laboratory Standards Institute published MIC interpretive criteria for 13 antimicrobial agents used for either therapy or prophylaxis of
Neisseria meningitidis
infections. The MIC method includes the use of lysed horse blood-supplemented Mueller-Hinton broth with incubation in 5% CO
2
for 20 to 24 h. Since some clinical laboratories might prefer the option of disk diffusion testing for infrequently encountered isolates a multicenter collaborative study was conducted to evaluate the reproducibility of a disk diffusion method for testing isolates of
N. meningitidis
. Interpretive criteria were developed for 12 antimicrobial agents. Four laboratories tested a common collection of 50 meningococcal strains and then tested 25 unique isolates per laboratory. Isolates were tested using Mueller-Hinton sheep blood agar plates incubated for 20 to 24 h in 5% CO
2
; they were also tested by the reference broth microdilution method in parallel. Pooling of the MIC and disk diffusion data from the common and unique isolates provided a sufficient sample size to develop susceptible, intermediate, and resistant zone diameter interpretive criteria using the error rate-bounded method for the following agents: chloramphenicol, trimethoprim-sulfamethoxazole, ciprofloxacin, and rifampin. Due to the lack of resistant strains at the present time, “susceptible only” interpretive criteria were proposed for cefotaxime, ceftriaxone, meropenem, azithromycin, and minocycline. The numbers of minor interpretive errors with penicillin and ampicillin disk tests were unacceptably high and precluded recommended testing of those agents by the disk method. However, amdinocillin, an agent that preferentially binds to the altered penicillin binding protein responsible for diminished penicillin susceptibility, has potential utility as a surrogate screening reagent for ampicillin resistance. A disk diffusion breakpoint was derived for nalidixic acid to serve as a surrogate marker for gyrase A mutations associated with diminished fluoroquinolone susceptibility. Disk diffusion testing with meningococci can be performed in a reproducible manner with several antimicrobial agents and represents a practical and cost-effective option for testing sporadic clinical isolates or for surveillance purposes by resource-limited laboratories.
Multilocus Sequence Typing Reveals Intrafamilial Transmission and Microevolutions of
Candida albicans
Isolates from the Human Digestive Tract
Authors: Bougnoux M.-E. , Diogo D. , François N. , Sendid B. , Veirmeire S. , Colombel J. F. , Bouchier C. , Van Kruiningen H. , d'Enfert C. , Poulain D.
Published: May 2006

Candida albicans
is a human commensal that is also responsible for superficial and systemic infections. Little is known about the carriage of
C. albicans
in the digestive tract and the genome dynamics that occur during commensalisms of this diploid species. The aim of this study was to evaluate the prevalence, diversity, and genetic relationships among
C. albicans
isolates recovered during natural colonization of the digestive tract of humans, with emphasis on Crohn's disease patients who produce anti-yeast antibodies and may have altered
Candida
sp. carriage.
Candida
sp. isolates were recovered from 234 subjects within 25 families with multiple cases of Crohn's disease and 10 control families, sampled at the oral and fecal sites. Prevalences of
Candida
sp. and
C. albicans
carriage were 53.4% and 46.5%, respectively, indicating frequent commensal carriage. No differences in prevalence of carriage could be observed between Crohn's disease patients and healthy subjects. Multilocus sequence typing (MLST) of
C. albicans
isolates revealed frequent colonization of a subject or several members of the same family by genetically indistinguishable or genetically close isolates. These latter isolates differed by loss-of-heterozygosity events at one or several of the MLST loci. These loss-of-heterozygosity events could be due to either chromosome loss followed by duplication or large mitotic recombination events between complementary chromosomes. This study was the first to jointly assess commensal carriage of
C. albicans
, intrafamilial transmission, and microevolution. The high frequency of each of these events suggests that the digestive tract provides an important and natural niche for microevolutions of diploid
C. albicans
through the loss of heterozygosity.
Increasing Incidence of Severe Epstein-Barr Virus-Related Infectious Mononucleosis: Surveillance Study
Authors: Tattevin Pierre , Le Tulzo Yves , Minjolle Sophie , Person Arnaud , Chapplain Jean Marc , Arvieux Cedric , Thomas Remi , Michelet Christian
Published: May 2006

Older patients are more susceptible to severe Epstein-Barr virus (EBV)-related infectious mononucleosis (IM). This condition may increase in industrialized countries where primary EBV infection occurs later in life. Between 1990 and 2004, 38 patients were admitted to our department with EBV-related IM. Two patients died. The annual incidence increased significantly (
r
= 0.623;
P
= 0.013).
Application of Minimal Sequence Quality Values Prevents Misidentification of the
bla
SHV
Type in Single Bacterial Isolates Carrying Different SHV Extended-Spectrum β-Lactamase Genes
Authors: al Naiemi Nashwan , Schipper Kim , Duim Birgitta , Bart Aldert
Published: May 2006

Nucleotide sequencing is the standard molecular method for determination of the β-lactamase gene present in an isolate. Using minimal sequence quality values prevents misidentification of
bla
SHV
genes, as illustrated by three strains of three different species that each contained two different
bla
SHV
alleles, SHV-2 and SHV-12.
Studies of specifically fluorinated carbohydrates. Part I. Nuclear magnetic resonance studies of hexopyranosyl fluoride derivatives
Authors: Hall L. D. , Manville J. F. , Bhacca N. S.
Published: May 2006

A detailed study has been made of both the 1H and 19F nuclear magnetic resonance (n.m.r.) spectra of a series of hexopyranosyl fluoride derivatives. Some of the 1H spectra were measured at 220 MHz. The 1H spectral parameters define both the configuration and the conformation of each of these derivatives. Study of the 19F n.m.r. parameters revealed several stereospecific dependencies. The 19F chemical shifts depend upon, (a) the orientation of the fluorine substituent with respect to the pyranose ring and, (b) the relative orientation of other substituents attached to the ring; for acetoxy substituents, these configurational dependencies appear to be additive. The vicinal19F–1H coupling constants exhibit a marked angular dependence for which Jtrans = ca. 24 Hz whilst Jgauche = 1.0 to 1.5 Hz for [Formula: see text] and 7.5 to 12.6 Hz for [Formula: see text] The geminal19F–1H couplings depend on the orientation of the substituent at C-2; when this substituent is equatorial JF,H is ca. 53.5 Hz and when it is axial the value is ca. 49 Hz.
Reactions of ozonides. VIII. An examination of the possibility of reversible ozonide formation using 14C labelling
Authors: Kerur Dundappa R. , Diaper Dennis G. M.
Published: May 2006

Carboxyl-14C-10-formyldecanoic acid was made by 14CO2 carbonation of 10-undecenylmagnesium bromide and ozonolysis of the product. Attempts were made to equilibrate its methyl ester with[Formula: see text]in various solvents. Little incorporation of label in the re-isolated ozonide was found, and it was concluded that under normal ozonolysis conditions the formation of ring ozonide is essentially irreversible. Slight incorporation in chloroform is explicable either by reversal of the Criegee mechanism of ozonide formation or by reversal of the recently suggested regenerative carbonyl – primary ozonide reactions.
The photochemical Beckmann rearrangement
Authors: Izawa H. , Mayo P. De , Tabata T.
Published: May 2006

The direct irradiation of aryl aldoximes gives the amide (the photochemical Beckmann rearrangement) by intramolecular oxygen migration. This has been shown by the rearrangement of 18O-labelled benzaldoxime in the presence of p-tolualdoxime: no exchange of label was observed.The rearrangement usually gives the amide, but in the case of the anisyl derivative the anilide was also obtained. The highest quantum yield for benzamide formation noted (in acetic acid) was 0.034, but the figure is dependent on irradiation time. The results of low-temperature irradiation suggest that an oxazirane is an intermediate. Phenyl-N-methyl oxazirane is converted into the amide on irradiation (though not thermally) and it seems likely that the reaction is induced, under the conditions of the reaction, by benzylic hydrogen abstraction by thermally produced small amounts of benzaldehyde; a fact which may explain the variation in quantum yield of amide formation with extent of irradiation. An additional route from oxazirane to amide may also be available.The activation of the oxime by high energy sensitizers under the most favorable conditions gives Φamide = 0.002, and so a singlet pathway for oxazirane formation is preferred. The main route for energy degradation appears to be by syn–anti isomerism. This can be induced by a variety of sensitizers and so can be a triplet process. The direct irradiation of benzaldoxime leads to isomerism with Φαβ = 0.40 and Φβα = 0.38. From these figures, together with the composition of the stationary state found, the composition of the sensitized stationary state can be calculated in fair agreement with the experimentally found value. This suggests that the isomerization following direct irradiation is also a triplet process.In a single example of an aralkyl ketoxime (p-anisylmethyl ketoxime) irradiation products of both aryl and alkyl migration, were found.
Structure of "phytic acids"
Authors: Johnson L. F. , Tate M. E.
Published: May 2006

Evidence is presented to show that cereal grain phytic acid has the myoinositol hexaorthophosphate structure suggested by Anderson and not the hydrated myoinositol tripyrophosphate structure proposed by Neuberg. DL-Myoinositol 1,6:2,3:4,5-tripyrophosphate which is structurally related to the Neuberg formulation has been prepared. The "phytic acid" fraction from chicken blood has been shown to be predominantly 1,3,4,5,6-myoinositol pentaphosphate. The structures assigned to these compounds have been confirmed by 31P nuclear magnetic resonance.
Application of interferometry to reaction kinetics: hydrolysis of ethyl acetate
Authors: O'brien R. N. , Glasel A.
Published: May 2006

The use of multiple-beam interferometry has been extended to the study of the kinetics of the hydrolysis of ethyl acetate in acid solution. The rate of change of refractive index in the reacting solution is shown to be directly proportional to the disappearance of the reactants and the appearance of products. The rate of movement of fringes on a wedge interferometer was measured with a photomultiplier tube by recording the response of the tube on passage of a bright fringe. A continuous uniphase output gas laser was used as a light source. Extremely small refractive index changes, hence very small concentration changes, can be detected. Design characteristics of the cell are discussed.
Analysis of line-width effects in the electron spin resonance spectra of monoprotonated semiquinones
Authors: Gough T. E.
Published: May 2006

Electron spin resonance spectra of monoprotonated p-benzosemiquinone, 2:6-dimethyl-p-benzosemiquinone, and durosemiquinone dissolved in tetrahydrofuran at −70 °C are reported. Under such conditions restricted rotation of the hydroxyl group causes the ring positions meta to the site of protonation to appear as non-equivalent, though this effect is not observed for monoprotonated durosemiquinone. The spectra of monoprotonated p-benzosemiquinone in tetrahydrofuran exhibit both anisotropic and alternating line-width trends; equations are presented which allow the separation of these two effects and the determination of the energy of activation for the rotation of the hydroxyl group as between 31 and 40 kJ/mole. Spectra of monoprotonated 2:3- and 2:5-dimethyl-p-benzosemiquinones in 1:2 dimethoxyethane at 20 °C are also reported.
Structure of lucidioline. An alkaloid of Lycopodium lucidulum
Authors: Ayer W. A. , Altenkirk B.
Published: May 2006

The alkaloid lucidioline is shown to have structure 1. The transformation of lucidioline into desacetyllycoclavine (8) is described.
Spectrofluorometric studies. V. 1,2,4- and 1,3,5-Trifluorobenzene
Authors: Semeluk G. P. , Stevens R. D. S. , Unger I.
Published: May 2006

The variation of fluorescence yield as a function of exciting wavelength for the title compounds has been examined. 1,3,5-Trifluorobenzene shows a maximum in fluorescence yield at an exciting wavelength λex = 2680 Å; for 1,2,3-trifluorobenzene, this maximum occurs near 2740 Å. Triplet yields for both molecules, based on the biacetyl sensitized emission technique, have been determined at various exciting wavelengths. The maximum triplet yield of 1,3,5-trifluorobenzene = 0.40 and occurs at λex = 2640 Å, while that of 1,2,4-trifluorobenzene = 0.64 at λex = 2780 Å. The triplet of the 1,2,4 isomer appears to lie below the triplet of cis-butene-2 and thus the olefin cis–trans isomerization technique cannot be used as a diagnostic for the triplet state of this molecule. The effect of two inert gases, cyclohexane and cis-butene-2, on both fluorescence and triplet yield has been studied.
Complexing, exchange, and redistribution reactions of some Group III and Group V fluorides and their anions
Authors: Brownstein S.
Published: May 2006

Complexing, fluorine exchange, and redistribution reactions were studied for systems containing BF3, PF5, AsF5, SbF5, and their anions BF4−, PF6−, AsF6−, and SbF6−. Fluorine resonance spectra were obtained for PSbF11− and AsSbF11−. Silver and tetrabutylammonium were used as cations in methylene chloride as solvent.
Mechanism of oxidation of alcohols with N-bromo succinimide
Authors: Venkatasubramanian N. , Thiagarajan V.
Published: May 2006

The kinetics of the oxidation of a number of aliphatic and aromatic secondary alcohols with N-bromo succinimide has been investigated. Electron-withdrawing substituents retard the reaction considerably and electron-releasing substituents increase the rate of oxidation. The Taft ρ* value is −2.56. Cis- and trans-4-t-butyl cyclohexanols are oxidized at nearly the same rates. There is also a good correlation between the rates of the NBS oxidations and Br2 oxidations of these alcohols. The results are interpreted in terms of a cyclic mechanism involving a rate-determining abstraction of the alpha hydrogen as a hydride anion.
Some metabolites of Alternariasolani
Authors: Stoessl A.
Published: May 2006

Pigments isolated from culture filtrates and mycelia of Alternariasolani were shown to be 5-hydroxy-7-methoxy-2-methylanthraquinone (1, 2-methylxanthopurpurin-7-methylether), 7-methoxy-2-methyl-3, 4,5-trihydroxyanthraquinone (2), 3,5-dihydroxy-7-methoxy-2-methylanthraquinone (3, macrosporin), 7-methoxy-2-methyl-1,2,3,4,5-pentahydroxy-1,2,3,4-tetrahydroanthraquinone (5, altersolanol A) and 7-methoxy-2-methyl-1,2,3,4-tetrahydro-2,3,5-trihydroxyanthraquinone (8, altersolanol B). 3 has been described previously and may have chemotaxonomic significance. Compounds 5 and 8 represent a new type of naturally occurring, reduced anthraquinone.
Tetrazolylacetic acids
Authors: Raap R. , Howard J.
Published: May 2006

The syntheses of several 1-,2- and 5-tetrazolylacetic acids are described. Isomeric tetrazolylacetic esters can be separated by fractional distillation or crystallization. 5-Hydroxytetrazole reacts with ethyl bromoacetate in the presence of triethylamine to give 1,4-dicarbethoxymethyl-5-tetrazolone. The use of nuclear magnetic resonance spectroscopy for the assignment of structural isomers is discussed.
α-Metallation and subsequent alkylation of alkyl alkanesulfonates
Authors: Truce W. E. , Vrencur D. J.
Published: May 2006

Strong bases affect α-metallation of alkyl alkanesulfonates; subsequent alkylation offers a useful approach to esters of the higher sulfonic acids.
7-O-β-D-Glucosyl-3′,4′,5-trihydroxy-6-methyl flavanone—a new C-methyl flavanone glycoside from Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] roots
Authors: Barton G. M.
Published: May 2006

A new C-methyl flavanone, 7-O-β-D-glucosyl-3′,4′,5-trihydroxy-6-methyl flavanone, has been obtained from healthy Douglas-fir [Pseudotsugamenziesii (Mirb.) Franco] root bark in a high yield of 2.6%. Its structure was elucidated by high resolution and mass spectrometry together with a variety of chemical and physical tests and confirmed by synthesis of its methylated aglycone. Pathological testing of this new glucoside against Poriaweirii Murr. is being undertaken.
The effect of pressure on the radiation-induced conductance of liquid hydrocarbons
Authors: Brazier D. W. , Freeman G. R.
Published: May 2006

An attempt was made to test the cavity model of electron localization in liquid hydrocarbons by measuring the effect of pressures up to 4000 bars on the radiation induced conductance of n-pentane, n-hexane, n-octane, cyclopentane, methylcyclohexane, and 2,2-dimethylbutane at 30°. Measurements at 3 and 56° were also made on n-hexane and n-octane. The relative induced conductance, i.e. the ratio of the induced conductance at pressure p to that at 1 bar, decreased with increasing pressure. The amount of decrease was slightly greater at low than at high temperatures. The behavior of 2,2-dimethylbutane was complex and is not understood. For the other liquids, it was concluded that the free ion yields remained constant or decreased somewhat with increasing pressure. An appreciable increase in the free ion yields, which is a possible implication of the cavity model of electron localization, did not occur. Therefore, either (a) the cavity model of electron localization in hydrocarbons is wrong, or (b) application of pressures up to 4000 bars did not appreciably alter the cavity concentrations in the liquids. Perhaps the cavity concentration is greatly reduced only by pressures great enough to cause a solid phase (glass or crystal) to form.
Infrared studies on rotational isomerism. III. 2-Chloro- and 2-bromo-ethanol
Authors: Buckley Paul , Giguère Paul A. , Schneider Michel
Published: May 2006

The relative intensities of the C—X stretching bands of the gauche and trans isomers in the vapor were measured as a function of temperature up to 165 °C for 2-chloroethanol, and up to 130 °C for 2-bromoethanol. From these the enthalpy differences between the two isomers were found to be 1.20 and 1.45 ± 0.1 kcal mole−1 respectively for the two halogenated ethanols. Similar measurements on the O—H stretching bands gave values higher than the above by 0.45 kcal mole−1 for both compounds. This apparent discrepancy is interpreted as due to a second gauche isomer, the OH group of which is not engaged in intramolecular hydrogen bonding, and which is less stable than the trans isomer.A study of the isotopic molecule ClCH2—CH2OD has led to unambiguous assignment of the OH bending and torsional frequencies. The spectra of the solid show that 2-chloroethanol can exist in two different crystalline phases: a stable one consisting of gauche molecules only, and a metastable one containing both isomers.
Ion–molecule reactions in vinyl fluoride
Authors: Herman J. A. , Harrison A. G.
Published: May 2006

The ion–molecule reactions in vinyl fluoride have been studied as a function of pressure and electron energy. The C2H2+ and C2HF+ fragment ions react predominantly by charge transfer while C2H3+ produces C2H4F+ and C4H5+. The C2H2F+ fragment forms C2H4F+, CHF2+, C2H3F2+, C4H4F+, and probably C2H3+. The rate constants for the individual reactions have been measured. The C2H3F+ ion reacts to form C3H5+, C3H4F+, C3H3F2+, and C4H5F+ (in minor yield), both by a second order and by a third order reaction. The rate constants and product distributions from the individual reactions have been evaluated. A number of consecutive reactions have been identified and shown to be third order processes.
Dimethyl and diphenyl formamide complexes of lanthanide perchlorates
Authors: Krishnamurthy S. S. , Soundararajan S.
Published: May 2006

N,N-Dimethyl formamide (DMF) and N,N-diphenyl formamide (DPF) complexes of six lanthanide perchlorates of the composition M(DMF)8(ClO4)3 and M(DPF)6(ClO4)3 where M = La, Ce, Pr, Nd, Sm, or Y have been prepared and characterized. The infrared spectra show that the amide is bonded to the metal through oxygen. Conductivity, molecular weight, and spectral studies indicate coordination numbers of eight and six for DMF and DPF complexes respectively, with the perchlorate groups remaining ionic.
On the reduction of the ozonides of selected phenylethylenes by triphenylphosphine
Authors: Carles Jacques , Fliszár Sándor
Published: May 2006

Triphenylphosphine has been found to reduce 18O labelled ozonides of styrene, stilbene, β-methylstyrene, and triphenylethylene by a very selective attack on the peroxidic oxygen atoms of the ozonides. The presence of ln electron withdrawing phenyl group attached to a C atom of the ozonide ring enhlnces the attack on the peroxidic oxygen adjacent to this C atom, whereas the presence of an electron releasing methyl group enhances the attack on the other peroxidic oxygen atom.
Coordination of silicon tetrafluoride with pyridine and other nitrogen electron-pair donor molecules
Authors: Guertin Jacques P. , Onyszchuk Mario
Published: May 2006

Silicon tetrafluoride reacts with pyridine, pyrrolidine, and piperidine forming solid 1:2 complexes. With ethylenediamine, the stable 1:1 complex results. These compounds are easily hydrolyzed and sublimed and have no measurable vapor pressure at 25°. Hydrolysis of SiF4•2C5H5N with aqueous HF produces pyridinium hexafluorosilicate (4), (C5H5NH+)2SiF62−. Ethylenediamine readily displaces pyridine from SiF4•2C5H5N, forming SiF4•NH2(CH2)2NH2. Infrared spectra of the complexes are compared in the 900–280 cm−1 region, but it was not possible to decide whether the pyrrolidine and piperidine complexes are cis- or trans-octahedral.
Reactions of alcohols adsorbed on MgO. Part I. Heterogeneous reactions with hydrogen atoms and trapped electrons at room temperature: a new technique in surface chemistry
Authors: Smith D. R. , Tench A. J.
Published: May 2006

A series of alcohols, adsorbed on MgO powder, have been bombarded by a stream of hydrogen atoms at room temperature and the radicals thus formed are detected by electron spin resonance. Methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and allyl alcohol have been studied. The radical species produced have been identified and radical lifetimes varying from minutes to hours at 300 °K have been observed. For methanol, the first monolayer appears to be chemisorbed as methoxy groups whereas the ethanol data indicate that some of the molecules in the first monolayer are physically adsorbed. The higher alcohols form secondary radicals via hydrogen elimination from the primary radical; the isopropyl alcohol radical appears to isomerize before losing hydrogen. Allyl alcohol undergoes hydrogen atom abstraction in preference to addition to the double bond and yields the α-hydroxy-allyl radical. Methanol and ethanol have also been reacted with electrons trapped on a MgO surface to form stable alkoxide ion radicals trapped at oxygen ion vacancies on the surface of the lattice.
Tensorial properties of an electronic Raman effect of the thulium ion
Authors: Koningstein J. A. , Ng Toa-ning
Published: May 2006

The low temperature laser excited Raman spectrum of the compound thulium gallium garnet reveals the presence of an electronic transition of the thulium ion. The tensor associated with this transition can contain some asymmetry. Polarization measurements show, however, that the amount of asymmetry is too small to be detectable.
Some comments on the Wigner tunneling formula
Authors: Nash J. C. , Laidlaw W. G.
Published: May 2006

Tunneling through a barrier is calculated with the Wigner distribution function. The use of a simple height-to-width formula for various potential types is illustrated. The effect of higher order terms is also investigated.
Signs of proton–proton and proton–fluorine spin–spin coupling constants in 2-fluoro-3-methylpyridine. Sigma and pi contributions to coupling in a nitrogen heterocycle
Authors: Schaefer T. , Danyluk S. S. , Bell C. L.
Published: May 2006

The signs of all proton–proton and proton–fluorine spin–spin coupling constants in 2-fluoro-3-methylpyridine have been determined by double and triple resonance experiments. The signs of the longrange coupling constants, JH,CH3 and JF,CH3 are the same as in fluorotoluene derivatives. Their magnitudes are consistent with the assumption that the nitrogen atom primarily polarizes the σ bonds in the molecule, leaving the π contribution to the long-range coupling relatively unaffected.
Carbonyl ammine complexes of ruthenium(II)
Authors: Allen A. D. , Eliades T. , Harris R. O. , Reinsalu P.
Published: May 2006

A series of carbonyl tetrammine and pentammine complexes of ruthenium(II) has been prepared. The compounds have been characterized by analytical techniques and by the reactions they undergo.Some carbonyl triammine and nitrogen tetrammine compounds are also reported.
Diethyl lead dinitrate
Authors: Potts D. , Walker A.
Published: May 2006

The reaction, at 0 °C, between tetra-ethyl lead and dinitrogen tetroxide in both nitromethane and diethyl ether as solvents has been studied. The product in both solvents is always diethyl lead dinitrate, the properties of which have been investigated and compared with both dimethyl tin dinitrate and triethyl lead nitrate. The infrared spectrum is consistent with covalent unidentate nitrate groups, while molecular weight and conductivity measurements indicate that the compound behaves essentially as a 1:2 electrolyte in water and dimethyl sulfoxide. Decomposition of diethyl lead dinitrate in solution and in the solid state is discussed with the aid of ultraviolet spectroscopy and thermogravimetric analysis.
Predissociation in N2 and O2
Authors: Hudson Robert D. , Carter Virginia L.
Published: May 2006

An outline discussion is given of some of the complications in the measurement of absorption cross sections which arise from finite instrumental bandwidths. Application is made to data on O2 and N2 from the literature.
Coupling reaction between 4-t-butyl-o-benzoquinone and methyl linoleate
Authors: Kato Takashi , Taniai Makoto , Yokoo Kazuyuki , Kumanotani Ju
Published: May 2006

This is the first report on the dehydrogenation-coupling reaction of an o-quinoid compound with a 1,4-diolefinic compound. The reaction of 4-t-butyl-o-quinone and methyl linoleate has been studied, and the product which has a 1-(2′-hydroxy-4′(or 5′)-t-butylphenoxy)-2,4-pentadienyl structure has been separated and identified.
Behavior of lead electrodes in sulfuric acid solutions. II
Authors: Tarter E. , Ekler K.
Published: May 2006

An attempt was made to clarify the question whether the variation in the length of the "first discharge plateau" with change in H2SO4 concentration was caused by a change in the efficiency of PbO2 formation or by a variation in its discharge rate. The relationships between acid concentration, "passivation time", amount of PbSO4 formed during passivation, and the quantity of PbO2 derived therefrom during charging were investigated. The amount of PbSO4 on the anode increased with a decrease in passivating acid concentration. More PbO2 was formed at lower charging acid concentrations. The higher the discharge acid concentration, the greater was its stabilizing effect on PbO2 discharge. The combination of two factors, i.e. a decrease of the amount of PbO2 formed at higher acid concentrations together with an increase in the PbO2 stability, gave rise to the maximum 10.5 N H2SO4.
The stabilization of alkoxide anions
Authors: Baird N. C.
Published: May 2006

Molecular orbital calculations by the MINDO method are reported for the valence electrons of HO− and a number of small alkoxide anions. The acidity order [Formula: see text] is predicted, in agreement with recent ion cyclotron resonance studies. The electron density distributions within the ions are discussed with reference to current models of the polarizability of alkyl groups.
2,4,4-Trimethylpentenyl anions
Authors: Hunter D. H. , Mair R. W.
Published: May 2006

The allylic anions derived by proton abstraction from 2,4,4-trimethyl-1-pentene 1 and 2,4,4-trimethyl-2-pentene 2 have been studied as short-lived intermediates. The anions were generated in t-butyl alcohol-O-d-potassium t-butoxide at 215 °C and relative rates of hydrogen–deuterium exchange and isomerization were compared. The isomerization of the thermodynamically less stable 2 to 1 occurs through the cis-allylic anion with a low 10% intramolecular component. The intermediate anion preferentially collapses to give 2 (3 to 1). Treatment of 1 leads more frequently into the less substituted allylic anion.
Proton magnetic resonance studies of hydrogen bonding of formamide with bromide ion in solution. The non-equivalence of the amide hydrogens
Authors: Green R. D.
Published: May 2006

The proton magnetic resonance spectrum of a dilute solution of formamide —15N in CH3CN at 15 °C undergoes definite changes as bromide ion in the form of (C4H9)4NBr is added. The two amide resonances shift downfield, but at different rates. It is found that each amide hydrogen forms hydrogen bonds with bromide ions, apparently by way of independent equilibrium processes. The hydrogen bond at the trans position to the carbonyl oxygen is favored by about 0.7 kcal mole−1 over that at the cis position. It is postulated that electrostatic repulsion between any base and the carbonyl oxygen of an amide group, tends to favor formation of hydrogen bonds at the more remote, trans, hydrogen. This may account for the formation of hydrogen-bonded chains by N-monosubstituted amides preferentially with the amide hydrogen trans to oxygen.
Some piperazino analogues of methadone and related ketones: a novel conversion of an N-carbethoxy to a triethylmethyl group
Authors: Dimmock J. R. , Harper N. J. , Islam R. , Casy A. F.
Published: May 2006

A number of derivatives of methadone and related compounds have been prepared, where the dimethylamino group has been replaced by a 4-substituted piperazino function. The preparation of these compounds involved the reaction of N-ω-cyanoalkyl-N′-carbethoxy piperazines with ethyl magnesium bromide, and various products were obtained. These included replacement of the N′-carbethoxy group by a triethylmethyl function and cleavage of the carbethoxy group. In some cases the ω-cyano group reacted to give the corresponding ketone. Reactions of 1-benzyl-4-carbethoxy piperazine with ethyl magnesium bromide and phenyl magnesium bromide gave no evidence for the formation of the triethylmethyl group. However, cleavage of the carbethoxy group occurred and there was evidence for the formation of the corresponding amide.
Electron spin resonance study of γ-irradiated ethyleneimine in the solid state
Authors: Cordischi D. , Blasi R. Di
Published: May 2006

The electron spin resonance (e.s.r.) study of the ethyleneimine in polycrystalline and glassy state shows that the radical [Formula: see text] is formed by γ-irradiation at 77 °K. The features of the e.s.r. spectrum of this radical are discussed in terms of the isotropic and anisotropic hyperfine coupling constants of the hydrogen and nitrogen nuclei. The effects of bleaching the γ-irradiated sample with visible and ultraviolet light are also reported.