bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical study of the effects of inferior and superior vocal fold surface angles on vocal fold pressure distributions
Authors: Li Sheng , Scherer Ronald C. , Wan MingXi , Wang SuPin , Wu HuiHui
Published: May 2006

Vocal fold geometry plays an important role in human phonation. A wide range of inferior and superior vocal fold surface angles has been shown to be present during phonation [Nanayakkara, Master’s thesis, Bowling Green State University, Bowling Green, OH (2005)]. This study explored how these angles affect pressure distributions on the vocal folds, and thus how they may affect phonation. The computational code FLUENT was used to obtain pressure distributions for laminar, incompressible flow. Eighteen inferior vocal fold surface angles and nineteen superior vocal fold surface angles were selected for three specific glottal angles, uniform 0°, convergent 10°, and divergent 10°. Minimal glottal diameter (0.01cm), transglottal pressure (8cm H2O), and glottal entrance radius (0.15cm) were held constant, and the glottal exit radius was constant for each glottal angle. Results suggest that the vocal fold surface pressures are independent of the inferior and superior vocal fold surface angles realistic for human phonation. These results suggest that, in contrast to the important effects of glottal entrance and exit radii, minimal diameter, and angle on intraglottal pressures, the inferior and superior vocal fold surface angles (excluding possible interactive effects with the false vocal folds) do not have an influence on the intraglottal pressures.
Tissue deformation induced by radiation force from Gaussian transducers
Authors: Myers Matthew R.
Published: May 2006

Imaging techniques based upon the tissue mechanical response to an acoustic radiation force are being actively researched. In this paper a model for predicting steady-state tissue displacement induced by a radiation force arising from the absorption of Gaussian ultrasound beams is presented. A simple analytic expression is derived that agrees closely with the numerical quadrature of the displacement convolution integrals. The analytic result reveals the dependence of the steady-state axial displacement upon the operational parameters, e.g., an inverse proportional relationship to the tissue shear modulus. The derivation requires that the transducer radius be small compared to the focal length, but accurate results were obtained for transducer radii comparable to the focal length. Favorable comparisons with displacement predictions for non-Gaussian transducers indicate that the theory is also useful for a broader range of transducer intensity profiles.
Language redundancy predicts syllabic duration and the spectral characteristics of vocalic syllable nuclei
Authors: Aylett Matthew , Turk Alice
Published: May 2006

The language redundancy of a syllable, measured by its predictability given its context and inherent frequency, has been shown to have a strong inverse relationship with syllabic duration. This relationship is predicted by the smooth signal redundancy hypothesis, which proposes that robust communication in a noisy environment can be achieved with an inverse relationship between language redundancy and the predictability given acoustic observations (acoustic redundancy). A general version of the hypothesis predicts similar relationships between the spectral characteristics of speech and language redundancy. However, investigating this claim is hampered by difficulties in measuring the spectral characteristics of speech within large conversational corpora, and difficulties in forming models of acoustic redundancy based on these spectral characteristics. This paper addresses these difficulties by testing the smooth signal redundancy hypothesis with a very high-quality corpus collected for speech synthesis, and presents both durational and spectral data from vowel nuclei on a vowel-by-vowel basis. Results confirm the duration/ language redundancy results achieved in previous work, and show a significant relationship between language redundancy factors and the first two formants, although these results vary considerably by vowel. In general, however, vowels show increased centralization with increased language redundancy.
A geometrically nonlinear finite-element model of the cat eardrum
Authors: Ladak Hanif M. , Funnell W. Robert J. , Decraemer Willem F. , Dirckx Joris J. J.
Published: May 2006

Current finite-element (FE) models of the eardrum are limited to low pressures because of the assumption of linearity. Our objective is to investigate the effects of geometric nonlinearity in FE models of the cat eardrum with an approximately immobile malleus for pressures up to ±2.2kPa, which are within the range of pressures used in clinical tympanometry. Displacements computed with nonlinear models increased less than in proportion to applied pressure, similar to what is seen in measured data. In both simulations and experiments, there is a shift inferiorly in the location of maximum displacement in response to increasingly negative middle-ear pressures. Displacement patterns computed for small pressures and for large positive pressures differed from measured patterns in the position of the maximum pars-tensa displacement. Increasing the thickness of the postero-superior pars tensa in the models shifted the location of the computed maximum toward the measured location. The largest computed pars-tensa strains were mostly less than 2%, implying that a linearized material model is a reasonable approximation. Geometric nonlinearity must be considered when simulating eardrum response to high pressures because purely linear models cannot take into account the effects of changing geometry. At higher pressures, material nonlinearity may become more important.
Interaction of reed and resonator by sound generation in a reed organ pipe
Authors: Miklós András , Angster Judit , Pitsch Stephan , Rossing Thomas D.
Published: May 2006

Interaction of reed and resonator in reed organ pipes without and with the resonator has been investigated. The wave form of the sound generated without the resonator attached is a periodic train (with the frequency of reed vibration) of decaying high frequency oscillation. The frequency of this oscillation is independent of the frequency of the reed vibration; it corresponds roughly to the fundamental acoustic resonance of the shallot. Another rather surprising phenomenon was also observed: without the pipe resonator, the reed vibration frequency, and correspondingly the sound frequency is a continuous function of the reed vibrating length, but when the resonator is added “forbidden” frequency domains occur in the vicinity of the eigenfrequencies of the resonator, and the sound frequency jumps abruptly from below to above each resonance frequency of the resonator, when the reed is shortened. This effect can be explained by the coupling between two oscillating systems, the reed and the acoustic resonator. The presented investigations result in a better understanding of the acoustical and mechanical aspects of sound generation in reed pipes, which may allow organ builders and voicers to easier pipe design and more accurate voicing to obtain the desired sound.
Binaural detection of 500-Hz tones in broadband and in narrowband masking noise: Effects of signal/masker duration and forward masking fringes
Authors: Bernstein Leslie R. , Trahiotis Constantine , Freyman Richard L.
Published: May 2006

NoS π thresholds for a 500-Hz tonal signal were measured with broadband and with narrowband maskers using a single-interval adaptive matrix procedure [C. Kaernbach, J Acoust. Soc. Am. 88, 2645–2655 (1990)]. The purpose of the study was to investigate and to account for the effects on thresholds of varying the durations of the signals and maskers and the durations of forward masking fringes that preceded the occurrence of signal-plus-noise. For detection in both broadband and narrowband noise, the addition of brief forward fringes of masking noise resulted in elevations in threshold for the shortest signal durations. Longer forward fringes led to larger decreases in threshold when the masker was broadband as compared to when the masker was narrowband. The complex patterning of the data was explained by the operation of: (1) “predetection” temporal integration associated with peripheral auditory filtering; (2) duration-dependent, across-frequency influences that differentially affect broadband and narrowband NoSπ thresholds, (3) “post-detection” temporal integration associated with the central binaural mechanism, and (4) consideration of the detection thresholds in terms of changes in interaural correlation rather than in terms of signal level or signal-to-noise ratio, per se.
Effect of modulation maskers on the detection of second-order amplitude modulation with and without notched noise
Authors: Uchanski Rosalie M. , Moore Brian C. J. , Glasberg Brian R.
Published: May 2006

The mechanisms underlying the detection of second-order amplitude modulation (AM) were explored. The detectability of second-order AM (fixed depth for each subject) was measured for first- and second-order modulation rates of 16 and 2Hz, respectively (slow-rate pair), and 50 and 10Hz, respectively (fast-rate pair), with no masker, a low-band modulation masker (centered at 2 or 10Hz), and a high-band modulation masker (centered at 16 or 50Hz). This was done in the absence and presence of an audio-frequency notched noise centered at the carrier frequency of 4000Hz. Both modulation maskers were “low-noise” noises, to prevent overmodulation. In the absence of notched noise, both modulation maskers impaired performance for the slow-rate pair, but only the low-band masker impaired performance for the fast-rate pair. When notched noise was present, the low-band masker had no significant effect for either rate pair and the high-band masker had an effect only for the slow-rate pair. These results suggest that second-order AM detection is mediated both by an envelope distortion component at the second-order rate and by slow fluctuations in the output of a modulation filter tuned to the first-order rate. When notched noise is present, the distortion component plays little role.
Cue weighting in auditory categorization: Implications for first and second language acquisition
Authors: Holt Lori L. , Lotto Andrew J.
Published: May 2006

The ability to integrate and weight information across dimensions is central to perception and is particularly important for speech categorization. The present experiments investigate cue weighting by training participants to categorize sounds drawn from a two-dimensional acoustic space defined by the center frequency (CF) and modulation frequency (MF) of frequency-modulated sine waves. These dimensions were psychophysically matched to be equally discriminable and, in the first experiment, were equally informative for accurate categorization. Nevertheless, listeners’ category responses reflected a bias for use of CF. This bias remained even when the informativeness of CF was decreased by shifting distributions to create more overlap in CF. A reversal of weighting (MF over CF) was obtained when distribution variance was increased for CF. These results demonstrate that even when equally informative and discriminable, acoustic cues are not necessarily equally weighted in categorization; listeners exhibit biases when integrating multiple acoustic dimensions. Moreover, changes in weighting strategies can be affected by changes in input distribution parameters. This methodology provides potential insights into acquisition of speech sound categories, particularly second language categories. One implication is that ineffective cue weighting strategies for phonetic categories may be alleviated by manipulating variance of uninformative dimensions in training stimuli.
Cluster control of acoustic potential energy in a structural/acoustic cavity
Authors: Tanaka Nobuo , Kobayashi Kozue
Published: May 2006

This paper is concerned with cluster control of acoustic potential energy in a cluster coupled structural/acoustic cavity using both active noise control (ANC) and active vibration control (AVC). First, fundamental characteristics of a cluster coupled cavity are discussed, intriguing phenomena being confirmed: the coupling is strictly selective; structural modes and acoustic modes interfere with each other if and only if they fall into the same cluster, and hence termed cluster coupling. It is found that acoustic potential energy is a resultant from each cluster contribution, and thus clustered acoustic potential energy in a cavity may be extracted via cluster filtering without causing observation spillover, and may also be controlled independently using cluster actuation without causing control spillover. Employing both cluster filtering and cluster actuation, an optimal cluster control law using both ANC and AVC for minimizing clustered acoustic potential energy is derived. Based upon the control law, cluster control may be achieved, enabling the implementation of a multi-SISO system that may significantly mitigate computation load, as opposed to a MIMO system, on a controller. Finally, a numerical simulation is conducted, demonstrating the cluster control effect for suppressing acoustic potential energy in the cluster coupled cavity.
Active control of buzz-saw tones: Experimental results from a laboratory-scale, no-flow rig
Authors: Wilkinson M. J. , Joseph P. F.
Published: May 2006

This paper details the results of an experiment on a small scale no-flow rig to control a spinning mode with similar characteristics to the modes generated by buzz-saw noise. The spinning mode (m=−3, n=1) is generated by a mode synthesizer ring which has similar characteristics to that of a low frequency buzz-saw mode. A control system using seven microphones and seven control actuators is used to minimize the sum of the squared pressures at the duct wall using a filtered reference least mean squares (FXLMS) algorithm. It is shown that at certain frequencies the sound power transmitted to the duct termination is reduced by 14.5dB. The control mechanisms at different frequency ranges are identified and discussed with reference to computer simulations. It is shown that cut-off modes excited by the secondary actuator array have a significant effect on control performance at frequencies close to the cut-on frequency of the (m=−4, n=1) mode.
Pseudo-3D modeling of a surface-bonded Lamb wave source
Authors: Moulin Emmanuel , Grondel Sébastien , Baouahi Mustapha , Assaad Jamal
Published: May 2006

In this paper, a simple technique allowing the prediction of the Lamb wave field excited in an isotropic plate by a transducer of finite dimensions is presented. The basic idea is to separate the problem into two uncoupled parts. First, the Lamb wave excitation problem, in the plane defined by the thickness and width directions of the transducer, is treated. Then the source diffraction effects in the plane of the plate can be quantitatively estimated. The subsequent formulation thus offers a simple way of developing three-dimensional (3D) solutions from a two-dimensional (2D) modeling. Compared to a heavy full-3D numerical modeling, this technique appears to be a very satisfying alternative.
Measurement and simulation of the channel intensity impulse response for a site in the East China Sea
Authors: Choi Jee Woong , Dahl Peter H.
Published: May 2006

A model for the channel intensity impulse response Ic(t) is presented that is generally applicable for source-receiver ranges less than ten water depths. The separate impulse response functions from each arrival, such as the single surface bounce or surface-to-bottom bounce, are modeled using bistatic scattering concepts and are incoherently summed for the total response function. The expression Ic(t) is equivalent to a time-averaged response and embodies the boundary scattering and reflection physics corresponding to the center frequency at which computations are made. To compare with observations, Ic(t) is convolved with representations of the 8- and 16-kHz continuous wave (CW) pulses, and an 8–16-kHz frequency-modulated (FM) pulse, that were used in the Asian Sea International Acoustics Experiment conducted in the East China Sea (depth 105m). For the FM case the computation frequency is 12kHz, the center frequency of the FM pulse. It is found that six primary arrivals dominate the response for ranges less than about 1km. With modeling of Ic(t) limited to these paths, the basic structure of Ic(t) is set by bottom properties and acquisition geometry with some changes in intrapath time spreading that depend on sea surface conditions.
Asynchrony and the grouping of vowel components: Captor tones revisited
Authors: Roberts Brian , Holmes Stephen D.
Published: May 2006

Asynchrony is an important grouping cue for separating sound mixtures. A harmonic incremented in level makes a reduced contribution to vowel timbre when it begins before the other components. This contribution can be partly restored by adding a captor tone in synchrony with, and one octave above, the leading portion of the incremented harmonic [Darwin and Sutherland, Q. J. Exp. Psychol. A 36, 193–208 (1984)]. The captor is too remote to evoke adaptation in peripheral channels tuned to the incremented harmonic, and so the restoration effect is usually attributed to the grouping of the leading portion with the captor. However, results are presented that contradict this interpretation. Captor efficacy does not depend on a common onset, or harmonic relations, with the leading component. Rather, captor efficacy is influenced by frequency separation, and extends to about 1.5 oct above the leading component. Below this cutoff, the captor effect is equivalent to attenuating the leading portion of the incremented harmonic by about 6dB. These results indicate that high-level grouping does not govern the captor effect. Instead, it is proposed that the partial restoration of the contribution of an asynchronous component to vowel timbre depends on broadband inhibition within the central auditory system.
Central connections of anamniote auditory otolith endorgans
Authors: McCormick Catherine A.
Published: May 2006

The ascending auditory pathways of anamniotes (fish and amphibians) are organized similarly to those of amniotes (reptiles, birds, and mammals). A common pattern for the flow of acoustic information—inner ear to first-order nuclei to higher-order auditory nuclei in the medulla, midbrain, thalamus, and cerebrum—probably evolved early in vertebrate history and was retained in extant fish and in terrestrial vertebrates (with taxon-specific modifications) despite variability in inner-ear acoustic receptors. Otolith endorgans subserve hearing in jawed fish; auditory fibers segregate from otolith endorgan vestibular fibers and supply auditory divisions of functionally mixed (auditory-vestibular) first-order nuclei. Amphibian auditory otolith endorgans are primarily seismic detectors complementing new sound-pressure receptors of the amphibian and basilar papillae. Otolithic and papillar auditory endorgans supply common areas within functionally mixed (auditory-vestibular) first-order nuclei. Uniquely in anurans, they also supply a discrete first-order auditory nucleus analogous to the amniote cochlear nuclei. Discrete first-order auditory nuclei are correlated with the evolution of a tympanic ear, an independently evolved condition in anurans and among amniotes. Thus, at the first-order level, the amphibian auditory pathway retains primitive organizational features present in fish auditory pathways. Convergent neuroanatomical specializations in anurans and amniotes may reflect common functional requirements.
Correlation between elastic constant and perpendicular magnetic anisotropy in cobalt/platinum superlattice thin films studied by picosecond ultrasounds
Authors: Nakamura Nobutomo , Ogi Hirotsugu , Yasui Takeshi , Hirao Masahiko
Published: May 2006

The easy magnetization direction of a Co monolayer thin film is always parallel to the film surface, but it can be perpendicular to the film surface for Co/Pt multilayer thin films when the Co layer consists of a few atomic layers. This property is called perpendicular magnetic anisotropy (PMA), achieving ultrahigh-density magnetic recording media. PMA occurs because of the large lattice misfit (near 10%) at the Co-Pt interfaces, and large elastic strains must affect the elastic constants through lattice anharmonicity. Thus, elastic constants and magnetic properties of Co/Pt superlattice thin film should show a correlation, which was investigated by picosecond ultrasound. The pulse-echo signals of the longitudinal wave traveling in the thickness direction were detected by the laser pump-probe technique, which gave the elastic constant C33. The film thickness was determined by the X-ray reflectivity measurement. Co/Pt superlattice thin films were prepared by the magnetron-sputtering method, changing the Pt-layer thickness between 0.2–2 nm and keeping the Co-layer thickness to be 0.4 nm. Total film thickness was near 80 nm. C33 showed good correlation with the degree of PMA and it differed from the modulus predicted from the elastic constants of bulk materials.
Sequence Analysis of the 144-Kilobase Accessory Plasmid pSmeSM11a, Isolated from a DominantSinorhizobium melilotiStrain Identified during a Long-Term Field Release Experiment
Authors: Stiens M. , Schneiker S. , Keller M. , Kuhn S. , Pühler A. , Schlüter A.
Published: May 2006

The genome ofSinorhizobium melilotitype strain Rm1021 consists of three replicons: the chromosome and two megaplasmids, pSymA and pSymB. Additionally, many indigenousS. melilotistrains possess one or more smaller plasmids, which represent the accessory genome of this species. Here we describe the complete nucleotide sequence of an accessory plasmid, designated pSmeSM11a, that was isolated from a dominant indigenousS. melilotisubpopulation in the context of a long-term field release experiment with genetically modifiedS. melilotistrains. Sequence analysis of plasmid pSmeSM11a revealed that it is 144,170 bp long and has a mean G+C content of 59.5 mol%. Annotation of the sequence resulted in a total of 160 coding sequences. Functional predictions could be made for 43% of the genes, whereas 57% of the genes encode hypothetical or unknown gene products. Two plasmid replication modules, one belonging to therepABCreplicon family and the other belonging to the plasmid type A replicator region family, were identified. Plasmid pSmeSM11a contains a mobilization (mob) module composed of the type IV secretion system-related genestraGandtraAand a putativemobCgene. A large continuous region that is about 42 kb long is very similar to a corresponding region located onS. melilotiRm1021 megaplasmid pSymA. Single-base-pair deletions in the homologous regions are responsible for frameshifts that result in nonparalogous coding sequences. Plasmid pSmeSM11a carries additional copies of the nodulation genesnodPandnodQthat are responsible for Nod factor sulfation. Furthermore, atauDgene encoding a putative taurine dioxygenase was identified on pSmeSM11a. AnacdSgene located on pSmeSM11a is the first example of such a gene inS. meliloti. The deducedacdSgene product is able to deaminate 1-aminocyclopropane-1-carboxylate and is proposed to be involved in reducing the phytohormone ethylene, thus influencing nodulation events. The presence of numerous insertion sequences suggests that these elements mediated acquisition of accessory plasmid modules.
Use of Fluorescence Resonance Energy Transfer for Rapid Detection of Enteroviral Infection In Vivo
Authors: Hwang Yu-Chen , Chen Wilfred , Yates Marylynn V.
Published: May 2006

Enteroviruses can be easily transmitted through the fecal-oral route and cause a diverse array of clinical manifestations. Recent outbreaks associated with enteroviral contamination in aquatic environments have called for the development of a more efficient and accurate virus monitoring system. To develop a simple, rapid, and direct method for identifying enteroviral infections, we generated a fluorescent reporter system in which genetically engineered cells express a hybrid fluorescent indicator composed of a linker peptide, which is exclusively cleaved by the 2A protease (2Apro), flanked with a cyan fluorescent protein (CFP) and a yellow fluorescent protein undergoing fluorescence resonance energy transfer. The covalent linkage between two fluorophores is disrupted due to 2Aproactivity upon viral infection, which results in an increase in CFP intensity. This allows the rapid (within 7.5 h) detection of very low numbers (10 PFU or fewer) of infectious enteroviruses.
Single-Nucleotide-Polymorphism-Specific PCR for Quantification and Discrimination of
Chlamydia pneumoniae
Genotypes by Use of a “Locked” Nucleic Acid
Authors: Rupp Jan , Solbach Werner , Gieffers Jens
Published: May 2006

Single-nucleotide polymorphisms (SNPs) are targets to discriminate intraspecies diversity of bacteria and to correlate a genotype with a potential pathotype. Quantification of polygenotypic populations supports this task for in vitro and in vivo applications. We present a novel assay capable of quantifying mixtures of two genotypes differing by only one SNP.
Incidence of
Helicobacter felis
and the Effect of Coinfection with
Helicobacter pylori
on the Gastric Mucosa in the African Population
Authors: Fritz E. Lekunze , Slavik Tomas , Delport Wayne , Olivier Brenda , van der Merwe Schalk W.
Published: May 2006

Helicobacter pylori
and
Helicobacter felis
are two of the
Helicobacter
spp. that infect humans.
H. pylori
has been linked to significant gastric pathology. Coinfection with
Helicobacter
spp. may influence infectious burden, pathogenesis, and antibiotic resistance; however, this has not been studied. The aims of this study were to identify the incidence of
H. felis
and to analyze the effects of coinfection with both organisms on gastric pathology in a well-characterized South African population. Biopsy samples from the gastric corpora and antra of volunteers (
n
= 90) were subjected to histological examination and PCR for the identification of
H. pylori
and
H. felis
. We further investigated the effect of global strain type on the occurrence of precursor lesions by assigning nucleotide sequences derived from PCR amplification of three genes to global groupings (ancestral Africa1, ancestral Africa2, ancestral Europe, ancestral Asia, and mixed).
H. pylori
was detected in 75 (83.3%),
H. felis
in 23 (25.6%), and coinfection in 21 (23.3%) of the volunteers by PCR.
H. felis
was randomly distributed among adults and children but clustered within families, suggesting intrafamilial transmission. Analysis of histopathology scores revealed no differences in atrophy, activity, and helicobacter density between
H. felis
-positive and
H. felis
-negative volunteers.
H. pylori
substrains common to southern Africa showed no differences in inflammation or atrophy scores. The incidences of
H. felis
and coinfection with
H. pylori
in the African population are high.
H. felis
infection, however, does not influence specific gastric pathology in this population.
Sensitivity of the Multispot HIV-1/HIV-2 Rapid Test Using Samples from Human Immunodeficiency Virus Type 1-Positive Individuals with Various Levels of Exposure to Highly Active Antiretroviral Therapy
Authors: O'Connell Robert J. , Agan Brian K. , Anderson Stephanie A. , Malia Jennifer A. , Michael Nelson L.
Published: May 2006

The Multispot HIV-1/HIV-2 rapid test detects human immunodeficiency virus type 1 (HIV-1) gp41 antibodies, which can wane over time in some HIV-1-infected populations, resulting in false-negative screening results. Multispot sensitivity was 100% using 248 sera from one such population, and it correctly identified serostatus in individuals who previously tested false negative with rapid testing.
Presence of a Novel DNA Methylation Enzyme in Methicillin-Resistant
Staphylococcus aureus
Isolates Associated with Pig Farming Leads to Uninterpretable Results in Standard Pulsed-Field Gel Electrophoresis Analysis
Authors: Bens Corina C. P. M. , Voss Andreas , Klaassen Corné H. W.
Published: May 2006

Genomic DNA from methicillin-resistant
Staphylococcus aureus
isolates recovered from pigs and their caretakers proved resistant to SmaI digestion, leading to uninterpretable results in standard pulsed-field gel electrophoresis. This is the result of a yet unknown restriction/methylation system in the genus
Staphylococcus
with the recognition sequence CCNGG.
Kinetics and mechanisms of the reaction between carbon monoxide and copper(II) in aqueous solution
Authors: Byerley J. J. , Peters E.
Published: May 2006

The kinetics of the reduction of copper(II) to copper(I) by carbon monoxide in aqueous solutions have been investigated at 120 °C and carbon monoxide pressures up to 1360 atm. The reaction is homogeneous and proceeds by two paths, one of which is virtually independent of carbon monoxide pressure due to the formation of a stable cuprous carbonyl complex Cu(CO)+. The second reaction path contains both a pH-dependent and pH-independent component. The rate-determining step in both paths appears to be the decomposition of a carbon monoxide insertion complex by a cupric ion. Complexing ligands such as acetate were observed to have a minor inhibiting effect on the overall reaction.
Synthetic approach to ryanodine; the use of O-spirodienone lactone in organic synthesis
Authors: Berney Daniel , Deslongchamps Pierre
Published: May 2006

The key steps for this synthetic approach are the preparation of o-spirodienone lactone 15, its reaction with methylvinyl ketone which gave 16 and 17, and the conversion of 16 and 17 into compound 19 by base. Finally ozonolysis of 26 followed by internal condensation gave compound 28.
Neutralization of dilute aqueous aluminium sulfate solutions with a base
Authors: Singh S. Shah
Published: May 2006

A theoretical treatment of the neutralization of dilute Al2(SO4)3 solutions with a base is presented and is supported by the experimental data. The formation of soluble complex AlSO4+; the first-stage hydrolysis product, AlOH2+, and the precipitation of amorphous aluminium hydroxy sulfate are the reactions controlling the conditions in solution up to 80% of neutralization with respect to aluminium. Beyond 80% of neutralization there is slow replacement of SO42− by OH− in the amorphous precipitate of aluminium hydroxy sulfate.
Photo-additions of aromatic hydrocarbons—indene and naphthalene with acrylonitrile
Authors: McCullough John J. , Huang C. W.
Published: May 2006

The photolyses of indene and naphthalene with acrylonitrile have been studied, and the products characterized. Indene reacts with acrylonitrile when the hydrocarbon absorbs light, or when a triplet sensitizer (acetophenone) is absorbing. Photolysis under the former conditions in ethanol yields 2-(1-indenylpropionitrile) (70%), 2-(3-indenylpropionitrile) (10%), and 6-cyano-2,3-benzobicyclo[3,2,0]hept-2-ene (20%). Base-catalyzed isomerizations of the substituted indenes are reported. On sensitization, cis- and trans-isomers of 7-cyano-2,3-benzobicyclo[3,2,0]hept-2-ene are formed, with a minor amount of indene dimer. The former isomers can be equilibrated with strong base. Adducts of 1,1-dimethyl- and 1,1-diphenylindene with acrylonitrile are also described, and nuclear magnetic resonance data reported. Naphthalene adds acrylonitrile on photolysis in t-butyl alcohol (pyrex filter) to afford trans-8-cyano-2,3-benzobicyclo-[4,2,0]-octa-2,4-diene (90%) and 1- and 2-naphthyl-2-propionitrile (10%). Sensitization with acetophenone gave no detectable products. Irradiation of the major product at 253.7 mμ through Vycor gave naphthalene. The preparative value of these reactions is considered and possible mechanisms are proposed.
Enzymic deacylation of esterified mono- and disaccharides. 3. The location of acetylated positions in partially acetylated sugars
Authors: Fink A. L. , Hay G. W.
Published: May 2006

The nitrate ester, formed by reaction with fuming nitric acid in acetic anhydride at 0 °C, was suitable to block free hydroxyl groups in partially acetylated sugars without acetyl migration. This allowed the acetylated positions in partially acetylated mono- and disaccharides to be located by the reaction sequence: nitration, deacetylation, methylation, de-nitration, disaccharide hydrolysis and methyl glycosylation (initial product identification by paper partition chromatography), acetylation, and analysis of the products by gas-liquid partition chromatography. D-Glucose, penta-O-acetyl-D-glucopyranose, and 2,3-di-O-acetyl-β-D-glucopyranose were used as test compounds in the evaluation of this scheme.
Kinetics and mechanism of the oxidation of formaldehyde by hexacyanoferrate(III) ion
Authors: Singh V. N. , Gangwar M. C. , Saxena B. B. L. , Singh M. P.
Published: May 2006

The kinetics of the reaction between formaldehyde and hexacyanoferrate(III) ion in alkaline medium has been investigated at four temperatures. The data show that the reaction is rapid initially, then follows a simple first order rate with respect to each of the hexacyanoferrate(III) ion, formaldehyde, and hydroxide ion. Calculations reveal that only 0.27% of the formaldehyde corresponds to the initial rapid reaction; the remaining 99.73% follows the kinetics described. The net rate of the oxidation of formaldehyde as measured by the consumption of hexacyanoferrate(III) ion, is given by[Formula: see text]
Interactions of formic acid, formaldehyde, and methanol with germania surfaces
Authors: McManus J. C. , Matsushita Kun-Ichi , Low M. J. D.
Published: May 2006

Infrared studies of the interaction of, respectively, formic acid, formaldehyde, and methanol with hydroxylated germania gel surfaces were made. Formic acid was dissociatively adsorbed to give covalently bonded formate species and new surface hydroxyl groups. Monomeric formic acid could not be observed. Degassing the treated sample at 246° removed most of the surface formate and the perturbing effects on the surface hydroxyls were also decreased. Two adsorbed species were observed when germania was exposed to high pressures (~10 Torr) of formaldehyde at room temperature. One species was very weakly bonded; it was removed by degassing at room temperature and its structure is tentatively taken as formaldehyde hydrogen-bonded to the surface hydroxyl groups. The other species had a spectrum very similar to polyoxymethylene, and it is proposed that it was in fact a surface polymer formed through the catalytic effect of the surface hydroxyl groups. Methanol was dissociatively adsorbed on germania surfaces. A species attributed to surface methoxide was formed and the concentration of the surface hydroxyl groups increased. Also, small concentrations of two other species were observed which gave absorptions at 2195 and 1727 cm−1, respectively. The band at 2195 cm−1 is assigned to a Ge—H species formed, possibly, at non-stoichiometric portions of the surface, while the latter species is tentatively ascribed to a surface formate species.
Alkaloids of fumariaceous plants. LVII. Miscellaneous observations
Authors: Manske R. H. F.
Published: May 2006

The isolation of a number of new alkaloids from plants previously investigated is reported. Several known alkaloids have been encountered for the first time in plants also previously examined.
Synthetic reactions by complex catalysts. XII. Copper-catalyzed reaction of isocyanide with alcohol
Authors: Saegusa Takeo , Ito Yoshihiko , Kobayashi Shiro , Hirota Kiwami , Takeda Nobuyuki
Published: May 2006

The reaction of alkyl isocyanide with alcohol to produce alkyl formimidate requires catalysis by metal compounds. The catalysts are classified into two groups. The first group includes metallic copper, and the oxides of copper (Cu (I) and Cu (II)), silver, and mercury, which induce the isocyanide reactions of various alcohols including saturated and unsaturated alcohols and amino-alcohol. The second group catalysts are the chlorides of copper (Cu (I)), silver, zinc, and cadmium, which cause the reactions of isocyanide only with special alcohols having strong coordinating tendencies toward the catalyst, as being exemplified by allyl alcohol and β-N,N-dimethylaminoethanol. Among these catalysts, metallic copper and copper oxides are the most effective and give the products almost quantitatively. The difference in catalyst activity between the two groups of catalysts has been explained by assuming a ternary complex consisting of the catalyst, isocyanide, and alcohol as the site of reaction.
14N nuclear magnetic resonance: amines and ammonium ions
Authors: Witanowski M. , Januszewski H.
Published: May 2006

The 14N nuclear magnetic resonance (n.m.r.) signals of alkylamines and ammonium ions are shifted to lower magnetic fields with the increasing number of alkyl groups at the carbon atom directly bonded to the nitrogen atom, and at the nitrogen atom itself. The resonance of an ammonium ion always occurs at a field lower than that for the corresponding amine. It seems that high-lying excited states, not only those corresponding to lowest-wavelength transitions, are important for an explanation of the observed resonance shifts. A downfield shift of the 14N resonance and a substantial increase in signal width, as compared with the spectra of neat amines, are observed for aqueous solutions of amines. There is a very characteristic chemical shift for the R—CH2—NH2 molecules (R = alkyl, phenyl, vinyl) in the 14N n.m.r. spectra.
An electron spin resonance study of ultraviolet photolyzed methanol adsorbed on porous high-silica glass
Authors: Shimizu Michie , Gesser H. D. , Fujimoto M.
Published: May 2006

The electron spin resonance (e.s.r.) spectra of •CH3, •CHO, H and/or D, and possibly •CH2OH or •CH2OD were found by the ultraviolet (u.v.) photolysis of methanol —OH or —OD on porous high-silica glass at 77 °K. These e.s.r. spectra resemble the results of the u.v. photolysis of X-irradiated methanol indicating that some perturbation and/or sensitization occurred in the molecules by the glass surface. The absence of e.s.r. spectra from the same systems on the acid-leached glass, on the totally fluorinated glass, or on the totally —OH covered glass suggests that (i) the co-existence of surface contaminants, such as Al and Zr and not B, and some of surface —OH could be responsible for producing these free radicals, and (ii) the methanols adsorbed on these glass surfaces are stabilized against u.v. photolysis.
1,3-Dipolar cycloaddition of nitrile oxides. II. Reactions with o-quinoid structures
Authors: Awad William Ibrahim , Sobhy Micheal
Published: May 2006

o-Chloro-, 2-chloro-4-methoxy-, and 5-chloro-3,4-methylenedioxy-benzonitrile oxides react with phenanthrenequinone, chrysenequinone, phenanthrenequinonimine, chrysenequinonimine, and phenanthrenequinone monoxime to give a 1:1 adduct. Tetrabromo-o-quinone gives an adduct with benzonitrile N-oxide in ratio of 1:2.When benzoyl chloride or benzyl chloride was allowed to react with benzonitrile oxide, dibenzohydroxamic acid, o-benzohydroxamic benzyl ether were obtained respectively.The constitution of the products is discussed.
Hydrogen bonding in some t-amino-alcohols related to methadone
Authors: Casy A. F. , Hassan M. M. A.
Published: May 2006

Hydroxyl stretching frequency data upon 1-dimethylamino-3,3-diphenylhexan-4-ol and related amino-alcohols are reported which give evidence of unusually strong intramolecular hydrogen bonding between the hydroxy and t-amino functions of these compounds. In corresponding salts, concentration independent vOH bands, typical of hydrogen bonded species, also occur and a bonded system comprising anion, OH, and N+H functions is proposed together with probable methadol base and salt conformations.
Atmospheric electron–ion and ion–ion recombination processes
Authors: Biondi Manfred A.
Published: May 2006

The electron–ion and ion–ion recombination processes of importance in the upper atmosphere are considered, and available laboratory experimental and theoretical information concerning the relevant processes is discussed. For atomic ions the principal electron–ion recombination process is radiative, with theory indicating that the two-body coefficient at ∼200 °K is ∼10−11 cm3/s and decreases with increasing electron temperature. Microwave afterglow/mass spectrometer studies of diatomic ionospheric ions (e.g. NO+, O2+, and N2+) show a loss by dissociative recombination with a coefficient substantially in excess of 10−7 cm3/s at 250 °K and decreasing with increasing electron and ion temperature. There is some evidence from flame studies that H3O+ ions exhibit a very large coefficient (10−6–10−5 cm3/s) at 300 °K. Ion–ion recombination evidently proceeds by mutual neutralization, with laboratory studies of ions such as NO+ and NO2− indicating a two-body coefficient of the order of 10−7 cm3/s at 300 °K. In the lower D region, three-body Thomson recombination may be important, since laboratory studies of "air" ions indicate a three-body coefficient of ∼2 × 10−25 cm6/s at 300 °K.
Semi-empirical electron impact cross sections for atmospheric gases
Authors: Peterson L. R. , Prasad S. S. , Green A. E. S.
Published: May 2006

The present paper summarizes conveniently the electron-impact cross sections for N2, O2, and O used in recent aurora and dayglow studies at the University of Florida. The cross section parameters in their present form are a natural outgrowth of (a) the availability of an increasing number of cross section measurements in the laboratory as well as field observations of spectral intensities, and (b) more realistic calculations.The values presented should serve as a useful interim reference list pending the full analyses of current extensive data. Their usefulness for practical applications to problems in aeronomy is enhanced by their integrable functional forms.
Comments, Replies, and Summary
Authors: Biondi M. A.
Published: May 2006

not available
Vacuum ultraviolet transition probabilities in C, N, O, and N2
Authors: Lawrence George M.
Published: May 2006

A review is made of the recent works on the transition probabilities for C, N, O, and N2 in the vacuum ultraviolet.
Deactivation of O(1S) and O2(b1Σg+)
Authors: Stuhl F. , Welge K. H.
Published: May 2006

Rate constants for the collisional deactivation of O(1S) and O2(b1Σg+) are reported. They are obtained by measuring the intensity decay of the O(1S → 1D) and O2(b1Σg+ → X2Σg+) emissions after a pulsed production of the excited species.
Diffusivity measurements of the argon–mercury vapor system
Authors: Spencer H. B. , Toguri J. M. , Kurtis J. A.
Published: May 2006

An experimental method for the determination of the diffusivities of metal vapor – gas mixtures has been examined. An investigation of the mercury vapor – argon system in the temperature range 180–340 °C indicated that the experimental diffusivities agreed well with the diffusivities calculated from the kinetic theory of gases. The temperature dependence of the diffusivity was found to vary with the absolute temperature to the 1.7 power.
Coefficient of thermal expansion of solid cyclohexane by means of dielectric constant measurements
Authors: Chan R. K. , Chew H. A.
Published: May 2006

A method has been devised to measure the coefficient of thermal expansion of solid cyclohexane from −80 to 0 °C by means of dielectric constant measurements in a spring-loaded apparatus. Assuming the Clausius–Mosotti equation to be valid, the coefficient of thermal expansion is given by[Formula: see text](∂ε/∂T)p for solid cyclohexane is found to be −9.6 × 10−4°C−1. Therefore, α = 6.0 × 10−4°C−1 at −40 °C and (∂α/∂T)p = 6.4 × 10−7°C−2.According to Crowe and Smyth (∂ε/∂T)p is +7 × 10−4°C−1 because it has been measured with a fixed amount of solid cyclohexane between the electrodes. Using a model calculation based on the equivalent circuit consisting of 3 series capacitors filled alternately with air and sample, it is shown that the apparent value of (∂ε/∂T)p actually changes sign.
Molecular rotational relaxation time of aniline in deuterated benzene solution at 20 °C
Authors: Bock E. , Tomchuk E.
Published: May 2006

The molecular rotational relaxation time of the aniline molecule in deuterated benzene solution was determined at 20 °C by pulsed nuclear magnetic resonance (n.m.r.) techniques. It was found that the rotational relaxation time, τr, in infinitely dilute deuterated benzene solution was 3.2 × 10−12 s, a value which is in fair agreement with the dielectric molecular relaxation time reported by Grubb and Smyth for aniline in dilute benzene solution.
Polarizations of atomic and molecular charge distributions
Authors: Bader R. F. W. , Keaveny I. , Runtz G.
Published: May 2006

It is shown that the dominant polarization of a molecular charge distribution in the region of a nucleus of an atom which employs p orbitals in its bonding (Be → F, Mg → Cl) is quadrupolar in nature, and dipolar for an atom which employs s orbitals (H, He, Li, Na). That these polarizations are of a fundamental nature is demonstrated by showing that they represent the primary response of a charge distribution to an electric field, whether it be internal or external, static or dynamic.
Electrochemistry of copper, silver, gold, gallium, indium, and thallium in fused AlCl3–NaCl–KCl eutectic
Authors: Anders Udo , Plambeck James A.
Published: May 2006

The electrochemistry of copper, silver, gold, gallium, indium, thallium, and their ions, and of chlorine and bromine in fused AlCl3–NaCl–KCl was investigated by electromotive force (e.m.f.) and voltam-metric techniques. Univalent oxidation states were observed for all the metals. In addition, copper was further oxidized to the divalent species while gallium and indium were oxidized to trivalent species. The standard potentials for the above couples were established in the AlCl3–NaCl–KCl eutectic at 135 °C.
π-Electronic structure and reactivity of phenoxazine (1), phenothiazine (2), and phenoxthiin (3)
Authors: Mantsch H. H. , Dehler J.
Published: May 2006

The ultraviolet, fluorescence, and phosphorescence spectra as well as the corresponding polarized excitation spectra were recorded for phenoxazine, phenothiazine, and phenoxthiin at 80 °K and discussed in terms of a number of theoretical transitions, calculated by a configuration interaction π-electron approximation.The computed transition energies and the reactivity indices (π-electronic charge, mobile bond order, free-valence index, superdelocalizability index, and localization energy) are in good agreement with experimental data and chemical evidence.
Nuclear magnetic resonance spectral parameters of α,α,α-trifluorotoluene
Authors: Kostelnik R. J. , Williamson M. P. , Wisnosky D. E. , Castellano S. M.
Published: May 2006

The 60 and 100 MHz proton spectra of α,α,α-trifluorotoluene have been recorded and analyzed in terms of chemical shifts and coupling constants. The results of the analyses are compared and the values of the spectral parameters discussed. The nuclear magnetic resonance spectral data of 2-chloro-5-nitro-α,α,α-trifluorotoluene are also reported.
Electron spin resonance spectra of triple ions: anisotropic effects in the hyperfine splitting patterns of 23Na counter-ions
Authors: Gough T. E. , Hindle P. R.
Published: May 2006

The formation, in tetrahydrofuran, of triple ions of the formula Na2Q+ (Q = p-benzosemiquinone, 2,3-, 2,5-, 2,6-dimethyl-p-benzosemiquinone, durosemiquinone) has been detected by electron spin resonance spectroscopy. The spectra show asymmetric broadening within the 23Na hyperfine multiplets. From the direction of this broadening, it is deduced that the sodium ions lie in the plane of the semiquinone anion, one sodium ion associating with each oxygen.