bluuebunny/crossref_metadata_2025 huggingface dataset:
Baroclinic Energy Flux at the Hawaiian Ridge: Observations from the R/P FLIP
Authors: Rainville Luc , Pinkel Robert
Published: July 2006

Estimates of baroclinic energy flux are made in the immediate “Nearfield” (September–October 2002) and 450 km offshore (“Farfield”; October–November 2001) of the Kaena Ridge, an active barotropic-to-baroclinic conversion site. The flux estimates are based on repeated profiles of velocity and density obtained from the Research Platform Floating Instrument Platform (FLIP) as an aspect of the Hawaii Ocean Mixing Experiment. Energetic beams associated with both semidiurnal and diurnal internal waves are observed in the Kauai Channel. Beam depths and orientations are consistent with generation along the upper flanks of the ridge. At the far-field site, the baroclinic energy flux is borne primarily by first-mode semidiurnal waves. The energy flux associated with the entire spectrum of internal waves is computed by cross-spectral analysis. Significant energy fluxes are found in the inertial, diurnal, semidiurnal, and twice-semidiurnal frequency bands. The semidiurnal energy flux strongly dominates the spectrum at both sites. The flux magnitude follows the spring–neap cycle of the semidiurnal barotropic tide. The averaged depth-integrated mode-1 semidiurnal energy flux (over the entire water column) in the Farfield is found to be 1.7 ± 0.3 kW m−1 away from the ridge, with peak values up to 4 kW m−1. Small fluxes toward the ridge are occasionally seen at neap tide. At both sites, energy fluxes in the diurnal frequency band represent 15%–20% of the semidiurnal energy flux. In the Farfield, the magnitude of the diurnal energy flux varies in accord with the fortnightly cycle of the barotropic semidiurnal tide, rather than with the diurnal forcing, suggesting that energy for those waves is supplied by a cross-frequency transfer from the low-vertical-mode M2 internal tide to higher-mode internal waves at frequencies ½M2. In the Nearfield, the diurnal flux varies with fluctuations in both diurnal and semidiurnal forcing.
Flow and Mixing around a Small Seamount on Kaena Ridge, Hawaii
Authors: Carter Glenn S. , Gregg Michael C. , Merrifield Mark A.
Published: July 2006

Microstructure observations over a small seamount on the Kaena Ridge, Hawaii, showed asymmetry in the along- and across-ridge directions. The ∼400-m-high seamount is on the southern edge of the ridge (centered at 21°43′49″N, 158°38′48″W), 42 km northwest of Oahu. A 1-km-resolution numerical simulation shows that the flow within the depth range of the seamount tends to be accelerated around the seamount rather than going up and over it. The flow patterns, however, are more complicated than for an isolated seamount because of the influence of the ∼3000-m-high Kaena Ridge. Comparison with the numerical simulations indicates that the across-ridge asymmetry, in which dissipation on the north-northeastern side of the seamount was higher and more concentrated toward the bed than on the south-southwestern side, is consistent with an M2 tidal beam generated at the northern edge of the ridge. The along-ridge asymmetry, with higher dissipation on the east-southeastern flank than on the west-northwestern flank, is in qualitative agreement with M2 shear variance from the model simulation. The average observed dissipation rate over the seamount was ɛ = 6.2 × 10−8 W kg−1, and diapycnal diffusivity was Kρ = 1.3 × 10−3 m2 s−1. Dissipation measurements following the 1000-m isobath south-southwest of the seamount suggest along-ridge internal tide generation caused by topographic steering that creates an along-ridge current over critical topography northwest of the seamount.
The Influence of Parental Support, Knowledge, and Authoritative Parenting on Hmong and European American Adolescent Development
Authors: Supple Andrew J. , Small Stephen A.
Published: July 2006

This study used a community-wide survey of adolescents to compare adolescent perceptions of parental support, knowledge, and authoritative decision making in samples of Hmong and European Americans. Additional analyses considered variation in parental influence on adolescent outcomes across these groups. The results suggested that Hmong American youth perceived less parental support and knowledge and were less likely to report authoritative decision making with parents. Parental support and knowledge were associated with higher self-esteem and grade point average (GPA) and lowered risky health behaviors in both samples. Results also suggested that authoritative decision making by mothers was a more important predictor of adolescent GPA and risky behaviors for the European American adolescents.
Is Internalized Homonegativity Related to Body Image?
Authors: Reilly Andrew , Rudd Nancy A.
Published: July 2006

The authors examined relationships among internalized homonegativity, body image, eating disturbance, and self‐esteem of gay men. Internalized homonegativity is believed to be experienced by all gay men and is tied to self‐esteem, which is a factor in the etiology of eating disorders and body image disturbance. It was hypothesized that internalized homonegativity would predict body image, self‐esteem, and eating disturbance. A total of 213 gay men participated in an online survey that used established measures. Results showed that specific components of internalized homonegativity predict body image, self‐esteem, and bulimic behaviors. Findings imply that internalized homonegativity is a viable link for assessing body image and self‐esteem among gay men. This study adds new dimension to the literature by linking internalized homonegativity with body image and by demonstrating a specific component of internalized homonegativity as predicting the variables tested. Future research and limitations are discussed.
Histone acetylation is associated with differential gene expression in the rapid and robust memory CD8+ T-cell response
Authors: Fann Monchou , Godlove Jason M. , Catalfamo Marta , Wood William H. , Chrest Francis J. , Chun Nicholas , Granger Larry , Wersto Robert , Madara Karen , Becker Kevin , Henkart Pierre A. , Weng Nan-ping
Published: July 2006

To understand the molecular basis for the rapid and robust memory T-cell responses, we examined gene expression and chromatin modification by histone H3 lysine 9 (H3K9) acetylation in resting and activated human naive and memory CD8+ T cells. We found that, although overall gene expression patterns were similar, a number of genes are differentially expressed in either memory or naive cells in their resting and activated states. To further elucidate the basis for differential gene expression, we assessed the role of histone H3K9 acetylation in differential gene expression. Strikingly, higher H3K9 acetylation levels were detected in resting memory cells, prior to their activation, for those genes that were differentially expressed following activation, indicating that hyperacetylation of histone H3K9 may play a role in selective and rapid gene expression of memory CD8+ T cells. Consistent with this model, we showed that inducing high levels of H3K9 acetylation resulted in an increased expression in naive cells of those genes that are normally expressed differentially in memory cells. Together, these findings suggest that differential gene expression mediated at least in part by histone H3K9 hyperacetylation may be responsible for the rapid and robust memory CD8+ T-cell response.
The effects of lestaurtinib (CEP701) and PKC412 on primary AML blasts: the induction of cytotoxicity varies with dependence on FLT3 signaling in both FLT3-mutated and wild-type cases
Authors: Knapper Steven , Mills Kenneth I. , Gilkes Amanda F. , Austin Steve J. , Walsh Val , Burnett Alan K.
Published: July 2006

The receptor tyrosine kinase FLT3 is a promising molecular therapeutic target in acute myeloid leukemia (AML). Activating mutations of FLT3 are present in approximately one-third of patients, while many nonmutants show evidence of FLT3 activation, which appears to play a significant role in leukemogenesis. We studied the effects of lestaurtinib (CEP701) and PKC412, 2 small molecule inhibitors of FLT3, on 65 diagnostic AML blast samples. Both agents induced concentration-dependent cytotoxicity in most cases, although responses to PKC412 required higher drug concentrations. Cytotoxic responses were highly heterogeneous and were only weakly associated with FLT3 mutation status and FLT3 expression. Importantly, lestaurtinib induced cytotoxicity in a synergistic fashion with cytarabine, particularly in FLT3 mutant samples. Both lestaurtinib and PKC412 caused inhibition of FLT3 phosphorylation in all samples. Translation of FLT3 inhibition into cytotoxicity was influenced by the degree of residual FLT3 phosphorylation remaining and correlated with deactivation of STAT5 and MAP kinase. FLT3 mutant and wild-type cases both varied considerably in their dependence on FLT3 signaling for survival. These findings support the continued clinical assessment of FLT3 inhibitors in combination with cytotoxic chemotherapy: Entry to future clinical trials should include FLT3 wild-type patients and should remain unrestricted by FLT3 expression level.
A direct comparison of protein interaction confidence assignment schemes
Authors: Suthram Silpa , Shlomi Tomer , Ruppin Eytan , Sharan Roded , Ideker Trey
Published: July 2006

Background

Recent technological advances have enabled high-throughput measurements of protein-protein interactions in the cell, producing large protein interaction networks for various species at an ever-growing pace. However, common technologies like yeast two-hybrid may experience high rates of false positive detection. To combat false positive discoveries, a number of different methods have been recently developed that associate confidence scores with protein interactions. Here, we perform a rigorous comparative analysis and performance assessment among these different methods.

Results

We measure the extent to which each set of confidence scores correlates with similarity of the interacting proteins in terms of function, expression, pattern of sequence conservation, and homology to interacting proteins in other species. We also employ a new metric, the Signal-to-Noise Ratio of protein complexes embedded in each network, to assess the power of the different methods. Seven confidence assignment schemes, including those of Bader et al., Deane et al., Deng et al., Sharan et al., and Qi et al., are compared in this work.

Conclusion

Although the performance of each assignment scheme varies depending on the particular metric used for assessment, we observe that Deng et al. yields the best performance overall (in three out of four viable measures). Importantly, we also find that utilizing any of the probability assignment schemes is always more beneficial than assuming all observed interactions to be true or equally likely.
Effect of Raloxifene on Bone Mineral Density in Premenopausal Women at Increased Risk of Breast Cancer
Authors: Eng-Wong J. , Reynolds J. C. , Venzon D. , Liewehr D. , Gantz S. , Danforth D. , Liu E. T. , Chow C. , Zujewski J.
Published: July 2006

Context: Raloxifene is a promising breast cancer prevention agent in postmenopausal women at increased risk for breast cancer. The effects of raloxifene in premenopausal women are unknown.

Objective: We evaluated the effect of raloxifene in premenopausal women at increased risk for breast cancer on bone mineral density (BMD).

Design: This was a phase II clinical trial.

Setting: This study was conducted at an academic medical center.

Participants: Thirty-seven premenopausal women at increased risk for breast cancer enrolled in the trial. Thirty subjects began treatment and 27 were evaluable.

Intervention: Raloxifene (60 mg daily) and elemental calcium (500 mg daily) were given for 2 yr. Subjects were followed up off medications for 1 yr.

Main Outcome Measure: The primary end point was the intrasubject percent change in BMD at 1 yr measured by dual-energy x-ray absorptiometry.

Results: The mean baseline lumbar spine density was 1.027 g/cm2. Lumbar spine density decreased 2.3% at 1 yr (P < 0.00001) and 3.5% at 2 yr (P < .00001). Percent change from yr 2 to 3 was +1.4%. The mean baseline total hip bone density was 0.905 g/cm2. Total hip density decreased 0.3% at 1 yr and 1.0% at 2 yr (P = 0.033). Percent change from yr 2 to 3 was +1.7%.

Conclusions: Raloxifene use is associated with a decrease in BMD in premenopausal women at increased risk for breast cancer. The clinical significance of this decrease is unknown and is attenuated with stopping raloxifene.
Serum Thyrotropin Concentration as a Novel Predictor of Malignancy in Thyroid Nodules Investigated by Fine-Needle Aspiration
Authors: Boelaert K. , Horacek J. , Holder R. L. , Watkinson J. C. , Sheppard M. C. , Franklyn J. A.
Published: July 2006

Context: Thyroid nodules and goiter are common, and fine-needle aspiration biopsy (FNAB) is the first investigation of choice in distinguishing benign from malignant disease.

Objective: The objective of the study was to assess whether simple clinical and biochemical parameters can predict the likelihood of thyroid malignancy in subjects undergoing FNAB.

Design: The design was a prospective cohort.

Setting: The study was conducted at a single secondary/tertiary care clinic.

Participants: One thousand five hundred consecutive patients without overt thyroid dysfunction (1304 females and 196 males, mean age 47.8 yr) presenting with palpable thyroid enlargement between 1984 and 2002 were evaluated by FNAB of the thyroid.

Intervention(s): There were no interventions.

Main Outcome Measures: Goiter type was assessed clinically and classified as diffuse in 183, multinodular in 456, or solitary nodule in 861 cases. Serum TSH concentration at presentation was measured in a sensitive assay in patients presenting after 1988 (n = 1183). The final cytological or histological diagnosis was determined after surgery (n = 553) or a minimum 2-yr clinical follow-up period (mean 9.5 yr, range 2–18 yr).

Results: The overall sensitivity and specificity of FNAB in predicting malignancy were 88 and 84%, respectively. The risk of diagnosis of malignancy rose in parallel with the serum TSH at presentation, with significant increases evident in patients with serum TSH greater than 0.9 mU/liter, compared with those with lower TSH. Binary logistic regression analysis revealed significantly increased adjusted odds ratios (AORs) for the diagnosis of malignancy in subjects with serum TSH 1.0–1.7 mU/liter, compared with TSH less than 0.4 mU/liter [AOR 2.72, 95% confidence interval (CI) 1.02–7.27, P = 0.046], with further increases evident in those with TSH 1.8–5.5mU/liter (AOR 3.88, 95% CI 1.48–10.19, P = 0.006, compared with TSH < 0.4 mU/liter) and greater than 5.5 mU/liter (AOR 11.18, 95% CI 3.23–8.63, P < 0.001, compared with TSH < 0.4 mU/liter). Males (AOR 1.8, 95% CI 1.04–3.1, P = 0.04), younger patients (AOR 1.1, 95% CI 1.01–1.15, P = 0.025), and those with clinically solitary nodules (AOR 2.53, 95% CI 1.5–4.28, P = 0.001) were also at increased risk. Based on these findings, a formula to predict the risk of the diagnosis of thyroid malignancy in individual patients, taking into account their gender, age, goiter type determined clinically, and serum TSH, was calculated.

Conclusions: The risk of malignancy in a thyroid nodule increases with serum TSH concentrations within the normal range. In addition to patient’s gender, age, and goiter type, the serum TSH concentration at presentation is an independent predictor of the presence of thyroid malignancy. We propose that these simple clinical and biochemical factors can serve as an adjunct to FNAB in predicting risk of malignancy.
Cushing’s Syndrome: Important Issues in Diagnosis and Management
Authors: Findling James W. , Raff Hershel
Published: July 2006

Context: The diagnosis, differential diagnosis, and treatment of Cushing’s syndrome are challenging problems in clinical endocrinology. We focus on critical questions addressing screening for Cushing’s syndrome, differentiation of Cushing’s subtypes, and treatment options.

Evidence Acquisition: Ovid’s MEDLINE (1996 through April 2006) was used to search the general literature. We also relied on previously published reviews and a recent monograph and cite a mix of primary articles and recent reviews.

Evidence Synthesis: Although this article represents our opinion, it draws heavily on a recent consensus statement from experts in the field and a recent monograph on Cushing’s syndrome.

Conclusions: We concluded that: 1) measurement of late-night or bedtime salivary cortisol is a useful approach to screen for Cushing’s syndrome; 2) measurement of suppressed plasma ACTH by immunometric assay is useful to differentiate ACTH-dependent and -independent Cushing’s syndrome; 3) inferior petrosal sinus sampling for ACTH should be performed in patients with ACTH-dependent hypercortisolism in whom a pituitary magnetic resonance imaging is normal or equivocal (in the absence of a pituitary ACTH gradient, prolactin levels should be measured to confirm the integrity of venous sampling); 4) computed tomography of the chest and abdomen and somatostatin receptor scintigraphy should be performed in patients with the occult ectopic ACTH syndrome; and 5) patients with Cushing’s disease should be referred to a neurosurgeon with extensive experience operating on corticotroph microadenomas. Bilateral laparoscopic adrenalectomy should be considered in patients with Cushing’s disease who fail therapies directed at the pituitary.
Hydrodimerization of Methyl Acrylate Catalyzed by Halogenotris(triphenylphosphine)cobalt
Authors: Kanai Hiroyoshi , Ishii Keiji
Published: July 2006

Methyl acrylate was hydrodimerized in a methanolic solution by CoX(PPh3)3 (X=halogen) into dimethyl adipate. The in situ prepared cobalt complexes from cobalt halides, triphenylphosphine, and zinc gave higher yields of the hydrodimer in the presence of alkali halides. A mechanism is proposed which involves the protonation of Co(I)–methyl acrylate π-complex to give (2-methoxycarbonylethyl)cobalt complex, followed by a further addition of methyl acrylate.
Deactivation of Excited 2-Naphthylamine Due to Hydrogen Bonding Interaction with Pyridines. Fluorescence and Picosecond Laser Photolysis Studies
Authors: Ikeda Noriaki , Okada Tadashi , Mataga Noboru
Published: July 2006

The mechanism of the strong fluorescence quenching observed when two conjugated π-electron systems are directly connected by hydrogen bonding has been studied by means of transient absorption spectral measurements with ps as well as ns laser photolysis method and fluorescence measurement. The bimolecular rate constants of quenching of 2-naphthylamine fluorescence by pyridine and 4-cyanopyridine have been determined in various solvents. The bimolecular reaction rate of fluorescence quenching by pyridine is smaller than the diffusion controlled one in many cases and depends considerably upon the dipole moment and the ability of formation of hydrogen bonding chain of solvent. However, the quenching by 4-cyanopyridine is diffusion controlled in every solvent examined here. By means of ps laser photolysis method, the state formed by charge transfer from excited 2-naphthylamine to hydrogen bonded pyridine in the quenching process has been observed for the first time. The possibility of the hydrogen atom transfer due to the mechanism of charge transfer followed by proton transfer in hexane solution is also discussed.
Molecular Motion in Methylammonium Hexahalotellurates(IV) as Studied by Means of the Pulsed Nuclear Magnetic Resonance
Authors: Furukawa Yoshihiro , Kiriyama Hideko , Ikeda Ryuichi
Published: July 2006

Molecular motion in solid (CH3NH3)2TeX6 (X=Cl, Br, and I) was studied by measuring the spin-lattice relaxation time, T1, of 1H and 35Cl nuclei in several crystalline phases appearing below room temperature. A deep minimum of the proton T1 was observed in the low-temperature phase of all the compounds, indicating that the methylammonium ion performs a rapid reorientation as a whole about its three-fold axis. The activation energies, Ea, for the motion of cations are determined to be 7.0, 3.7, and 2.7 kJ/mol for X=Cl, Br, and I respectively. In (CH3NH3)2TeI6, which has the lowest Ea value, the relaxation process associated with the tunneling of the cation is apparent at low temperatures. For all the complexes studied, a shallow T1 minimum ascribable to the independent rotation of the CH3 and NH3 groups in the cation was observed on the high-temperature side of each deep T1 minimum. The 35Cl T1 of (CH3NH3)2TeCl6 exhibited a distinct minimum at the lower phase-transition point at 139 K and a discontinuity at the higher one near 230 K. The hindered rotation of the [TeCl6]2− octahedron occurs in the room-temperature phase, with an Ea value of 48 kJ/mol.
Reactions of trans- and cis-Dichlorobis(benzonitrile)platinum(II) with Acetylacetonate and Benzoylacetonate Carbanions. Formation of N-Acetyl β-Ketoamine Complexes by the Acetyl Group Migration
Authors: Uchiyama Toshihiko , Takagi Kazuhiko , Matsumoto Keiji , Ooi Shun’ichiro , Nakamura Yukio , Kawaguchi Shinichi
Published: July 2006

trans-Dichlorobis(benzonitrile) platinum(II) reacted with twice the molar amount of thallium(I) acetylacetonate and benzoylacetonate in dichloromethane at room temperature to afford mainly N-acetyl β-ketoamine chelates, trans-[Pt{N(COMe)=C(Ph)CH=COMe(and Ph)}2] (1a and 3a). This N,O-chelate structure of 1a was determined by X-ray analysis. Reactions of cis-[PtCl2(PhCN)2] gave C-acetyl and C-benzoyl β-ketoamine chelates, cis-[Pt{NH=C(Ph)C(COMe(and Ph))=COMe}2], together with other minor products. Formation of these β-ketoamine chelates is explained by the nucleophilic reactions of the β-diketonate carbanions at the coordinated cyanide carbon atom, followed by migration of the acetyl group or the methine proton of the nucleophiles onto the imino nitrogen atom formed during these reactions. In the presence of free β-diketones, migration of the acyl group was generally suppressed; this led to high yields of C-acyl complexes especially in reactions of cis-[PtCl2(PhCN)2]. In each case, the reaction proceeded with retention of the geometrical configuration around the central metal atom. The structures of other products, including a compound obtained by acid hydrolysis of 1a, were explored and discussed, based on IR and 2H NMR data.
Bis(β-diketonato)-palladram(II) and -platinum(II) Complexes
Authors: Okeya Seichi , Ooi Shun’ichiro , Matsumoto Keiji , Nakamura Yukio , Kawaguchi Shinichi
Published: July 2006

A number of palladium(II) and platinum(II) bis-chelates have been prepared which contain one kind of symmetric or unsymmetric β-diketonate anions, or involve two different β-diketonate anions. Existence of the cis and trans isomers in solution of the binary chelates of unsymmetric β-diketones was confirmed by 1H and 13C NMR spectroscopy. Geometrical isomerization of the palladium(II) complexes to attain equilibrium in solution is fast, while the platinum(II) complexes are quite inert. The mixed-ligand chelates are stable in solution, showing no sign of disproportionation. The isomeric pairs of bis(1-phenyl-1,3-butanedionato)palladium(II), bis(2,4-hexanedionato)palladium(II), and bis(1,1,1-trifluoro-2,4-pentanedionato)platinum(II) were isolated, and molecular structure of the cis isomer of the first complex was determined by X-ray analysis.
Adsorption of N-Dodecyl-β-alanine to the Spread Monolayer of Lecithin or Dilaurin
Authors: Tajima Kazuo , Tsutsui Takao
Published: July 2006

The adsorption of N-dodecyl-β-alanine (NDA) was studied at the air–solution interface with the spread film of l-α,β-dimyristoyllecithin (DML) or α,α′-dilaurin (DIL). The adsorbed amounts were measured by radiometry using tritium-labelled NDA, combined with surface pressure measurements. Measurements of IR, DSC, and NMR were made in order to determine the bulk properties of amphoteric moieties in the mixture of DML and NDA. For the mixed monolayer of NDA and DML or DIL, the surface composition vs. area curves were obtained at various surface pressures. The molecular interaction in monolayer was discussed on the basis of the excess free energy of mixing, which was calculated at various surface pressures and compositions. As a result, the mixing of DIL and NDA in monolayer was ideal at surface pressures less than 5 mN m−1, whereas the mixed monolayer of DML and NDA showed a remarkable condensation in surface molecular area. Such a large condensation at low surface pressure was concluded to be due to the formation of ion pairs between the choline and alanine moieties on the water surface, by referring to the findings obtained by studying the lipid properties in the bulk phase. It was also found that the DML–NDA monolayer near close packing exhibited various types of complicated behavior, depending on the surface compositions. The appreciable differences in the nature of the amphoteric moieties in DML and NDA molecules can explain these findings.
Dynamic Structure of the Potent Uncoupler SF 6847 (3,5-Di-t-butyl-4-hydroxybenzylidenemalononitrile) and Its Derivatives
Authors: Yoshikawa Kenichi , Kumazawa Noriyuki , Terada Hiroshi , Ju-ichi Motoharu
Published: July 2006

The steric and electronic structures of the most potent uncoupler of oxidative phosphorylation known, SF 6847, and its derivatives were studied. 1H and 13C NMR measurements showed that the malononitrile moiety is not planar with the benzene ring and that its intramolecular motional freedom is reduced on acid dissociation of the phenolic proton. The activation energies of the tumbling motion of the malononitrile moiety in the anionic forms of SF 6847 and its derivatives were also determined from their 1H NMR measured at various temperatures. The CNDO/2 and ab initio MO calculations of the model compounds of SF 6847 showed that the planar form is quite unstable and that the malononitrile moiety is twisted considerably relative to the benzene ring. The effect of the dynamic structure on the acidity of SF 6847 was discussed based on the above results.
Preparation of Several 1,5,5,11-Pentamethyltricyclo[6.2.1.02,6]undecane Derivatives
Authors: Inouye Yoshinobu , Fukaya Chikara , Kakisawa Hiroshi
Published: July 2006

1,6-Diketone, available in eight steps from homocamphorquinone, was converted into 1,5,5,11,11-pentamethyltricyclo[6.2.1.02,6]undecan-7-one by treatment with potassium t-butoxide and then lithium dimethylcuprate, while α,α-dimethyl-γ-valerolactone, prepared in five steps from homocamphor, was converted into 1,5,5,11,11-pentamethyltricyclo[6.2.1.02,6]undec-2-en-4-one by treatment with diphosphorus pentoxide–methanesulfonic acid.
The Nitration of Acylpentamethylbenzenes and 1,3-Diacyltetramethylbenzenes Bearing, as the Acyl Components, Pivaloyl, Trichloroacetyl, and Tribromoacetyl Groups. Exclusive Attack on the Methyl Group at the Most Crowded Site
Authors: Suzuki Hitomi , Hashihama Mitsuyuki , Mishina Tadashi
Published: July 2006

When treated with concentrated nitric acid in dichloromethane at room temperature, the title compounds undergo an exclusive attack on the methyl group at the most crowded site, giving 6-acyl-2,3,4,5-tetramethylbenzyl nitrates, and 2,6-diacyl-3,4,5-trimethylbenzyl nitrates and/or (2,6-diacyl-3,4,5-trimethylphenyl)nitromethanes respectively, as the major products. While the predominant mode of the side-chain substitution reactions is nitrooxylation for acylpentamethylbenzenes and 1,3-dipivaloyl-2,4,5,6-tetramethylbenzene, it shifts to nitration for 1,3-bis(trihalogenoacetyl)-2,4,5,6-tetramethylbenzenes. Nitrodeacylation is seen to some extent for pivaloylbenzenes, but not for trihalogenoacetylbenzenes. The exclusive attack on the methyl group at the most hindered position can be explained by a sequence involving the attachment of a nitronium ion at the site meta to the acyl group, followed by a proton release from the resulting arenium ion to form a nitromethylenecyclohexadiene intermediate, which is then transformed into the benzylic compounds via a benzyl cation/nitrite anion pair.
Synthesis and Reactions of Perylenecarboxylic Acid Derivatives. VIII. Synthesis of N-Alkyl-3,4:9,10-Perylenetetracarboxylic Monoanhydride Monoimide
Authors: Nagao Yukinori , Misono Takahisa
Published: July 2006

The condensations of 3,4 : 9,10-perylenetetracarboxylic dianhydride with alkylamines (isobutyl-, pentyl-, hexyl-, and octylamines) were spectroscopically determined. Under all of the reaction conditions employed, N-alkyl-3,4 : 9,10-perylenetetracarboxylic monoanhydride monoimide (2a–d) (alkyl=a; isobutyl, b; pentyl, c; hexyl, d; octyl) were obtained. As the reaction proceeded, the yield of 2a–d increased at an initial stage but decreased gradually after reaching a maximum. This maximum yield of 2a–d was: 2a; 85–88%, 2b; 85–89%, 2c; 78–84%, 2d; 79–85%. The kinetics of the reaction were also examined.
Emission Spectra of Aromatic Hydrocarbons by Controlled Electron Impact
Authors: Ogawa Teiichiro , Yamami Naoki , Tsuji Masaharu , Nishimura Yukio
Published: July 2006

The emission spectra of benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes, cymene, and naphthalene were investigated under controlled electron-impact excitation. These aromatic hydrocarbons showed a characteristic band in the 250–400 nm region and several bands of such excited fragment species as H and CH. The characteristic bands are similar to those of fluorescence spectra obtained by optical excitation and, thus, were assigned to fluorescence emissions of the parent molecules. The intensity of the fluorescence emission of benzene decreased at higher electron energies, and fragment emissions became dominant above 100 eV. However, its vibrational structure did not change for electron energies of 5–60 eV. This indicates that cascade processes from high-lying states are negligible for benzene. The fluorescence emission of naphthalene shifted to a shorter wavelength for low electron energies. Together with a theoretical estimation based on the Born approximation, cascade effects from higher excited states (S2 and S3) are found to be the major source of the fluorescence emission of naphthalene.
The Vacuum Ultraviolet Absorption Spectra of Fatty Acid Multilayers
Authors: Nagahira Yukio , Matsuki Kazunori , Fukutome Hideo
Published: July 2006

The electronic absorption spectra of fatty acid multilayers were measured in the vacuum ultraviolet region with an energy below 10 eV. From the chain length dependence of the spectra, the strong absorption (above 8 eV) was assigned to the σ-σ* transitions in the alkane chain moiety, and the weaker one (below 8 eV), to the transitions in the car boxy lie acid and metal car boxy late moieties. The polarized spectra of the Ba stearate multilayer showed that the band near 8.8 eV was polarized perpendicularly to the alkane chain. The spectra of the stearic acid multilayer without metal ions and the multilayer of the Zn stearate showed that their alkane chains were titled against the normal of the layer plane.
Kinetic Isotope Effect of Chemically Activated Vinyl Radicals
Authors: Kowari Ken-ichi , Sugawara Ko-ichi , Sato Shin , Nagaset Shigeru
Published: July 2006

The apparent decay rates of hydrogen and deuterium atoms in the reactions with acetylene-d0 and -d2 in helium in the pressure range from 100 to 800 Torr (1 Torr=133.3 Pa) have been measured by the pulse radiolysisLyman-α absorption method at 300±2 K. The helium pressure dependence of the rate constants was well interpreted in terms of the RRKM theory including a tunneling effect, using the geometry and force constants of the activated complex and vinyl radical estimated by the ab initio calculation. (S. Nagase and C. W. Kern, J. Am. Chem. Soc., 101, 2544 (1979).)
Chlorination of Polyacrylonitrile and Analysis of Its Products
Authors: Okamoto Masao , Yamada Ry\={o}ji , Ishizuka Osamu
Published: July 2006

Chlorination of polyacrylonitrile (PAN) was carried out by passing dried chlorine gas through a tetrahydrothiophene 1,1-dioxide (sulfolane) solution of PAN or a powdery mixture of PAN with sodium chloride. The chlorinated products were examined by comparison with acrylonitrile-α-chloroacrylonitrile (CAN) copolymers corresponding to α-chlorinated PANs. In solution the reaction proceeded easily below 100 °C, but due to side reactions analysis of the products was difficult. In the powdery mixture hardly any reaction took place below 100 °C, but in the range 120–140 °C, the reaction proceeded smoothly and its rate became ca. 2.7 times in proportion as its temperature was raised by 10 °C. The chlorinated products were investigated by means of infrared and thermal analyses. The chlorinated moiety consists mainly of α,β-dichlorinated units, which seem to result from the addition of chlorine to the double bonds produced by dehydrochlorination after β-chlorination. These chlorinated products were dehydrochlorinated at lower temperature than acrylonitrile-CAN copolymers, but in many respects they resemble each other in the behavior of thermal degradation.
Generalized Graph-theoretical Formula for London Diamagnetism
Authors: Aihara Jun-ichi
Published: July 2006

The previous graph-theoretical formula for London diamagnetism was improved so as to include all kinds of cyclic conjugated systems. Bicyclo[6.2.0]decapentaene was then found to be diatropic but antiaromatic even though the central π bond was elongated.
The Transition-metal Catalyzed Dehalogenation of Aromatic Halides by NaOH–Alcohols. A Facile Method of Destroying Aromatic Polyhalides
Authors: Okamoto Tadashi , Oka Shinzaburo
Published: July 2006

Aromatic halides are dehalogenated by heating with NaOH in alcoholic solvents in the presence of transition metal salts, such as rhodium(III) chloride or palladium(II) acetate and triphenylphosphine. Bis(pentabromophenyl) ether was converted into diphenyl ether in 2-propanol when treated for 5 h at 355 K with a catalytic cycle of more than 80.
Neutron Diffraction Study of Aqueous Hydrochloric and Hydrobromic Acid Solutions
Authors: Ohtomo Norio , Arakawa Kiyoshi , Takeuchi Makoto , Yamaguchi Toshio , Ohtaki Hitoshi
Published: July 2006

The structure factors Sm(Q) over a wide range of Q(1.7–25 Å−1) for aqueous solutions of DC1 and DBr (ca. 1 M) at room temperature have been determined by means of LINAC-TOF neutron diffraction. The intramolecular structures of D2O and D3O+ in the solutions are found to be identical with those in the “revised watery model” for water. Applying the subtraction method of analysis to diffraction data for the solutions, we have obtained the following results with respect to the structure of the nearest hydration shell around ions in the DCl and DBr solutions: (a) D3O+ is tetrahedrally coordinated with four water molecules and Cl− and Br− are octa-hedrally coordinated with six ones, (b) the O–O distances between the central oxygen atom and that of hydrated water molecules for D3O+ are 2.88±0.05 Å, (c) the anion-oxygen distances are 3.10±0.05 Å for Cl− and 3.21±0.05 Å for Br−, and (d) around cations (D3O+) water molecules take the configuration to orient the axis of one of the two lone-pair hybrids on a straight line joining an oxygen atom and the cation, while around anions (Cl− and Br−) those take the configuration to orient the vector which bisects the D–O–D angle on a straight line joining an oxygen atom and the cation.
Determination of Hyperoxide in Dimethyl Sulfoxide by Photometric Titration with Iodine
Authors: Kitamura Katsumi , Hasegawa Koichi , Mochizuki Katsura , Imamura Taira , Fujimoto Masatoshi
Published: July 2006

The concentration of hyperoxide, O2−, in dimethyl sulfoxide (DMSO) was determined by photometric titration with iodine. The validity of the method was confirmed on the basis of stoichiometry by use of the standardized hyperoxide solution in the reaction of the complex, MoO(tpp)NCS, with methanol, where TPP denotes α,β,γ,δ-tetraphenylporphyrin.
The Cycloaddition of Nitrilimines with 1,2-Dibenzoylethylenes
Authors: Oida Tatsuo , Shimizu Tomio , Hayashi Yoshiyuki , Teramura Kazuhiro
Published: July 2006

The cycloaddition of nitrilimines with 1,2-dibenzoylethylenes gave an unexpected 1,3-diaryl-4-benzoylpyrazole and benzoic acid, along with an expected cycloadduct, 1,3-diaryl-4,5-dibenzoyl-2-pyrazoline, and its dehydrogenated product, 1,3-diaryl-4,5-dibenzoylpyrazole. The elimination of the benzoyl group from the pyrazoline followed by dehydrogenation was shown to be the course of the unusual reaction.
Esterification of Carboxylic Acids by Alcohols with 2-Chloro-1,3,5-trinitrobenzene as Condensing Agent
Authors: Takimoto Seiji , Inanaga Junji , Katsuki Tsutomu , Yamaguchi Masaru
Published: July 2006

When mixtures of carboxylic acids or their sodium salts and alcohols were treated with 2-chloro-1,3,5-trinitrobenzene in the presence of pyridine under mild conditions, the corresponding carboxylic esters were formed. The yields and the rates of the ester formation depended on the types of the acids and the alcohols used.
The Magnetic Circular Dichroism of the Conjugated O- and S-Heterocycles
Authors: Igarashi Nobuko , Tajiri Akio , Hatano Masahiro
Published: July 2006

The MCD spectra of the monobenzo and dibenzo derivatives of thiophene and furan are reported; especially in dibenzofuran, two electronic origins are revealed in its lowest energy absorption band. The quantum-mechanical calculations of the transition energies and the Faraday parameters elucidate the experimental data to a fair extent, suggesting similarities in the electronic structures of the lower-lying excited states of furan and thiophen derivatives.
Structure of the Complex of Neodymium Nitrate with Pentaethylene Glycol
Authors: Hirashima Yoshiyuki , Kanetsuki Koji , Shiokawa Jiro , Tanaka Nobuo
Published: July 2006

Crystals of the complex, Nd(NO3)3–HO-(CH2CH2O)5H, are monoclinic. The Nd atom is coordinated by ten oxygen atoms, four from two bidentate nitrate ions and six from a pentaethylene glycol. The pentaethylene glycol forms a ring-like structure similar to that of crown compounds.
Synthesis and Reactions of Perylenecarboxylic Acid Derivatives. X. Synthesis of N-Alkyl-3,4-perylenedicarboximide
Authors: Nagao Yukinori , Misono Takahisa
Published: July 2006

N-Alkyl-3,4-perylenedicarboximides (alkyl=methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, and octyl) were prepared by the decarboxylation of N-alkyl-3,4:9,10-perylenetetracarboxylic monoanhydride monoimides (same alkyls) in potassium hydroxide solution.
The Characteristic Behavior of Recoil Tritium Atom in Solid Neopentane at 77 K. The Application of a Hot Zone Model
Authors: Aratono Yasuyuki , Tachikawa Enzo , Miyazaki Tetsuo , Sakurai Masayuki , Fueki Kenji
Published: July 2006

The behavior of recoil tririum atoms in solid neopentane containing a small amount of alkane has been studied at 77 K by means of ESR spectroscopy and radio-gas chromatography. Though it was reported that the H (or D) atoms produced in the radiolysis and photolysis of solid neopentane react selectively with the solute alkane, the T atoms neither diffuse into the matrix at 77 K nor react selectively with the solute alkane. Most of the recoil T atoms react in their own track. The results are explained by a hot-zone model. The radius and the duration time of the hot zone are estimated to be ≈60 Å and ≈10−10 s respectively.
A New Method for Conformational Analysis by Photoelectron Spectroscopy with Application to Alkyl-substituted Styrenes
Authors: Kobayashi Tsunetoshi , Arai Tatsuo , Sakuragi Hirochika , Tokumaru Katsumi , Utsunomiya Chikatoshi
Published: July 2006

A new method for molecular conformational analysis using photoelectron spectral data was developed and applied to alkyl-substituted styrenes as an example. The dihedral angle between the phenyl ring and the olefinic group planes, θ, in each molecule is evaluated by comparing the observed difference between the first and the third vertical ionization energies, ΔEiv1.3, with the empirically estimated ΔEiv1.3  vs. θ curve, the alkyl substituent effect being taken into account by the first order perturbation theory. The new method gives reasonable results consistent qualitatively with those given by other former methods.
Mechanism of the Current Doubling Effect. I. The ZnO Photoanode in Aqueous Solution of Sodium Formate
Authors: Fujishima Akira , Kato Tamihiko , Maekawa Etsuro , Honda Kenichi
Published: July 2006

Current doubling mechanism of the photoanodic reaction of sodium formate at the ZnO electrode is re-examined. Quantitative analysis of the reaction products revealed that ZnO electrode corroded during the current doubling reaction, which has not been previously reported. However, zinc ions were formed with about 50% of current efficiency. Carbon dioxide, instead of oxygen, was formed during the reaction. These experimental observations strongly suggested mechanism proposed by earlier workers were incorrect. A new mechanism is proposed.
The IR Spectra of CsxV2O5 (x=0–0.66)
Authors: Kera Yoshiya
Published: July 2006

The IR spectra of Cs–vanadates (C=[Cs]/[V]=0–0.332) were recorded in the 650–1200 cm−1 region. In the V2O5, which had cautiously been purified, the V=O stretching band was found at 1022 cm−1, and the V–O–V stretching band, at 815 cm−1. Upon the addition of Cs, sharp new bands began to appear at 965 cm−1 at C=0.0042 and also at 1000 cm−1 at C=0.0120, and a shift in the 815-cm−1 band was found. Finally, at C=0.332 the original 1022-cm−1 band was replaced by the 965 and 1000 cm−1 bands, the intensity ratio (I965⁄I1000) of which was 2.0. The X-ray diffraction pattern of the last sample was in agreement with that of CsV3O8. The IR and the X-ray results suggest that the CsV3O8 phase appears at around C=0.004. Based on the band shifts of 1022→965 and 1000 cm−1, the force constant and the bond strength of V=O in CsV3O8 were discussed. With respect to the band shift in the 815-cm−1 region with the increase in the Cs content, the corretion of Δ\ ildeν to C1⁄3 is shown in C<0.020.
Preparation and Properties of Monoalkylnickel(II) Complexes NiR(NR1R2)L2 Having Imido, Imidazolato, or Methyl Phenylcarbamato-N Ligand
Authors: Yamamoto Takakazu , Kohara Teiji , Yamamoto Akio
Published: July 2006

Reactions of dialkylnickel(II) complexes NiR2L2 1 (R=CH3, C2H5; L=1/2 bpy(2,2′-bipyridine), 1/2 dpe (1,2-bis(diphenylphosphino)ethane), PEt3) with compounds having acidic N–H bonds (succinimide, phthalimide, diacetamide, pyromellitimide (1,2 : 4,5-benzenebis(dicarboximide)), imidazole) gave corresponding monoalkylnickel(II) complexes having Ni–N bond formulated as NiR(NR1R2)L2. A reaction of NiMe2(PEt3)2 with CH3OH and phenyl isocyanate gives NiMe(N(Ph)COOMe)(PEt3)2. The IR, NMR, and visible spectroscopic studies of the complexes indicate that the electronegativity of Ni is enhanced by the replacement of one of the two R groups in 1 with the NR1R2 ligand. NMR spectra of complexes of a type NiMe(NR1R2)(PEt3)2 show that they have trans-configurations. Thermolyses of the monoalkylnickel(II) complexes start at temperatures higher by 80–100 °C than those of 1, liberating RH, R–R, and olefin R(–H). Exposure of monoethylnickel(II) complexes to air releases ethylene as the main gaseous product. Reactions of the complexes of a type NiR(phthalimido)L2 with R′X (R′=C6H5, C6H5CH2) and C6H5COCl produce N-alkyl- or N-arylphthalimide and ketone C6H5COR, respectively.
Catalysis by Mixed Oxide Perovskites. II. The Hydrogenolysis of C3–C5 Hydrocarbons on LaCoO3
Authors: Ichimura Kenji , Inoue Yasunobu , Yasumori Iwao
Published: July 2006

The catalytic hydrogenolysis of C3–C5 alkanes on LaCoO3 perovskite oxide was found to show a highly selective formation of methane in the temperature range of 350–620 K. The reaction order with respect to the hydrocarbon pressure was unity in every hydrogenolysis, whereas the hydrogen order increased from zero for propane to 1.0 for butane and isobutane and to 2.0 for pentane, isopentane, and neopentane. The activation energies of the reactions ranged from 120 for propane to 32 kJ mol−1 for butane. The reaction of propane or butane with D2 on LaCoO3 provided large fractions of methane [D3] and [D4], but a negligible amount of deuterium-exchanged alkanes. An equilibrium among the gaseous H2, HD, and D2 was reached. These hydrogenolyses are described by a mechanism involving the almost concurrent repture of all the carbon-carbon bonds in the alkanes by the attack of adsorbed hydrogen atoms, and were proposed to be catalyzed by a synergetic effect; the CO3+ ion is effective in breaking the C–C bond, whereas the La3+ and O2− ions serve to supply hydrogen atoms to the decomposed species. The reaction of propene or butenes with hydrogen produced the corresponding alkanes and methane. The kinetic analyses showed that the fractions of methane produced consecutively via the alkanes amounted to 16% for propene and to more than 93% for butenes. The observed pressure dependence and deuterium distributions in the alkene hydrogenation were interpreted in terms of the associative mechanism. The correlation between the structures of the reactant molecules and of the active sites present on LaCoO3 was briefly discussed.
The Structure of Liquid Water by Neutron Scattering
Authors: Ohtomo Norio , Tokiwano Kazuo , Arakawa Kiyoshi
Published: July 2006

A comprehensive analysis of the structure of liquid water was performed by combining neutron and X-ray diffraction data. A formula expressing the structure factor of fluids composed of small molecular clusters was obtained and applied to the analysis. In the interpretation of the diffraction data, the tetrahedral pentamer model as an aggregate of the regular tetrahedral pen tamers is considered to be the best structure model of liquid water from the excellent agreement between calculated structure factors and experimental data. Some critical discussions about other structure models were made.
Optical Resolution of Heterohelicenes by High Performance Liquid Chromatography
Authors: Nakagawa Hiroko , Ogashiwa Susumu , Tanaka Hisao , Yamada Koh-ichi , Kawazura Hiroshi
Published: July 2006

Heterohelicenes up to 15 rings were resolved by high performance liquid chromatography (HPLC) on silica gel covalently linked with a chiral charge transfer complexing agent 2-(2,4,5,7-tetranitro-9-fluorenylideneaminooxy)propionic acid(TAPA). The efficiency of resolution was discussed in terms of the helical structure of heterohelicenes.
ESR Spectra of Six-coordinate Cobalt(III) Tetraphenylporphyrin Cation Radicals Generated by Electrochemical Oxidation
Authors: Ohya-Nishiguchi Hiroaki , Khono Masahiro , Yamamoto Kiyoko
Published: July 2006

The ESR spectra of the paramagnetic species generated electrochemically from α,β,γ,δ-tetraphenylporphinatocobalt(II), [CoII(tpp)], have been observed under the conditions of low-temperature, in chlorinated or nonchlorinated solvents, and in the presence of various supporting electrolytes. From the ESR parameters obtained, three different paramagnetic species, [CoIII(tpp)]2+(X−)2, [CoIII(tpp)]2+(Y−)2, and [CoIII(tpp)]2+(X−)(Y−), have been confirmed. The ESR spectrum of thermally and optically accessible paramagnetic species in the solution of chlorotetraphenylporphinatocobalt(III) has been reproduced by the pertinent combination of solvent and supporting electrolyte, and well interpreted by assuming the formation of [CoIII(tpp)]2+(Cl−)2. Arguing from a correlation between the hfcc of cobalt and nitrogen nuclei in this species, a spin-polarization mechanism is proposed to interpret the cobalt hfcc.
Chloride-35 NMR Studies of the Ion Pairing of the Chloride Ion in Water and Aqueous Acetone
Authors: Yudasaka Masako , Sugawara Tadashi , Iwamura Hiizu , Fujiyama Tsunetake
Published: July 2006

The chloride-water mixture and the chloride-water-acetone mixtures were studied by measuring the 35Cl NMR spectra. From the line-width analyses, it has been concluded that the line-widths of the chloride solutions are affected only by the nearest neighbours of the chloride ions, which makes it possible to study the interaction between the chloride ion and the solvent molecules microscopically. The problem concerning the ion pair formation in solutions was discussed. It has been shown that the observation of the concentration dependence of line-widths can be very powerful method for the detection of contact ion pairs formed in the solutions.