bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaction of Alkynyl(phenyl)(p-phenylene)bisiodonium Ditriflates with Nucleophiles. High Reactivity of the Alkynyl Component
Authors: Kitamura Tsugio , Fukuoka Takahiro , Zheng Lei , Fujimoto Takeshi , Taniguchi Hiroshi , Fujiwara Yuzo 
Published: June 2006

Abstract
Reaction of alkynyl(p-phenylene)bisiodonium ditriflates with potassium thiocyanate in DMF gave alkynyl thiocyanates and p-iodophenyl(phenyl)iodonium triflate. The latter was readily removed by washing with water. The exclusive sulfur attack of thiocyanate ion suggests that the alkynyl group behaves as a soft acceptor of nucleophiles. The reactions with the enolate anion of 2-phenyl-1,3-indandione in DMF afforded 2-(1-cyclopentenyl)-2-phenyl-1,3-indandiones in the cases of 1-hexynyl- and 1-octynyl-(p-phenylene)bisiodonium ditriflates. In the reactions of 3,3-dimethyl-1-butynyl-, phenylethynyl-, and trimethylsilylethynyl-(p-phenylene)bisiodonium ditriflates, 2-alkynyl-2-phenyl-1,3-indandiones were obtained. The same reactions with the enolate anion of 2-phenyl-1,3-indandione in a mixed solvent of 2-methyl-2-propanol and THF improved the yields of the 1-cyclopentenyl- and alkynyl-substituted indandiones. A large difference in the reaction pathways between the (p-phenylene)bisiodonio and phenyliodonio moieties was observed in the sterically hindered 3,3-dimethyl-1-butynyl systems.
Bindings of a Secondary Polymer to Monodisperse Colloidal Silica Particles Modified with Poly(maleic anhydride–styrene) for Controlling the Surface Polarity
Authors: Yoshinaga Kohji , Teramoto Makoto 
Published: June 2006

Abstract
A polymer modification of monodisperse colloidal silica (120 nm in diameter) and control of the surface polarity were studied. The binding of poly(maleic anhydride–styrene) to the silica particles and successive grafting of amino-terminated polymethacrylates with methyl, hexyl, and dodecyl ester groups afforded unimodal composite particles, which were dispersible in a low-polar solvent of ethyl acetate. The bindings of the secondary polymer were dependent on the molecular structure of the polymer as well as the reaction conditions. The surface polarity was estimated by aggregation of the particles in an ethyl acetate–methanol cosolvent, monitored by the absorbance of a suspension containing the composite particles at 500 nm. The polarity was significantly affected by the main chain length of the secondary polymer of the polymethacrylates rather than the bound polymer chain number or the branch alkyl ester group of the polymer. For highly modified composite particles, it was observed that the carboxyl group, simultaneously formed in the binding of the secondary polymer, contributed to the surface polarity.
Ab Initio Molecular Orbital Studies of Singlet Oxygen Reactions of Olefins, Enol Ethers, and Enamines
Authors: Yoshioka Yasunori , Yamada Satoru , Kawakami Takashi , Nishino Masamichi , Yamaguchi Kizashi , Saito Isao 
Published: June 2006

Abstract
Ab initio molecular orbital (MO) studies of singlet oxygen reactions of olefins, enol ethers, and enamines were carried out. The relative stabilities of biradical (BR), the so-called perepoxide-like (PE), perepoxide-like zwitterionic (PEZW) and zwitterionic (ZW) intermediates for singlet oxygen reactions of these species are described theoretically, together with their ionization potentials, molecular structures and solvation energies. The activation energies for the ene and dioxetane formation reactions were found to be determined by the electron-donating properties of substituents introduced to these substrates. The following conclusions were drawn from these calculated results: (1) A nonradical transition state with a PE-like conformation is the most plausible for ene reactions of allylic olefins and enol ether with allylic hydrogens. (2) A BR mechanism is favorable for the (2 + 2) reactions of singlet oxygen with simple olefins in the gas phase. (3) A nonconcerted mechanism via polar (PEZW, ZW) intermediates is operative for (2 + 2) cycloadditions of unsymmetrical enol ethers in the solution phase, whereas the (2a + 2a) mechanism and a two-step mechanism via the PE intermediate are conceivable for the (2 + 2) reactions of symmetrical olefins in the solution phase. The implications of these theoretical results to the mechanisms of singlet oxygen reactions are discussed in relation to various experimental results, such as the stereochemistry, isotope effects, solvent effects and laser-photolysis experiments.
Theoretical and Experimental Studies of a Charge-Transfer Mechanism for Biomimetic Oxygenations of Phenol and Indol Derivatives
Authors: Yoshioka Yasunori , Yamanaka Syusuke , Yamada Satoru , Kawakami Takashi , Nishino Masamichi , Yamaguchi Kizashi , Nishinaga Akira 
Published: June 2006

Abstract
The structures and stabilities of organodioxide anions, charge-transfer (CT) complexes between carbanions and molecular oxygen, and related solvated clusters were investigated using ab initio and semiempirical MO plus intermolecular CT theories. The computational results, together with experimental evidence, have revealed the characteristics of potential curves, indicating that the nonradical mechanism via CT complexes is operative for base-catalyzed dioxygenation reactions of phenol and indole derivatives. The following conclusions were drawn from the present calculations: (1) The reactions of carbanion with triplet molecular oxygen proceed through a one-electron transfer (ET) mechanism from carbanion to 3O2. (2) The base-promoted phenol monoanion reacts with molecular oxygen via two different mechanism: one is the CT mechanism, where the triplet CT complex is formed and a spin inversion from a triplet CT complex to a singlet CT one occurs in aprotic solvents; the other involves the one ET mechanism assisted by hydrogen bonding in a protic solvent. (3) The one ET does not occur for the free monoanions of the indole derivatives; rather these species are readily oxygenated by organo-cobalt catalysts. (4) For the flavin derivatives, the CT mechanism is applicable in an aprotic solution, while both the CT and one ET mechanisms are conceivable in aqueous solution. The implications of these results to biological dioxygenations by metallo-dioxygenases are discussed in relation to biomimetic oxygenations of phenol and indole derivatives.
Crystal and Molecular Structures of Novel Metal–Carbene Complexes I. {1,1′-(Perhydropyrimidine-1,3-diyl-κC2)bis[(alkyl/arylimino)methanethiolato-κ2SS′]}(triphenylphosphine)–Pt/Pd Complexes
Authors: Yasui Masanori , Yoshida Satoshi , Kakuma Seiji , Shimamoto Souichi , Matsumura Noboru , Iwasaki Fujiko 
Published: June 2006

Abstract
2,3,4,5-Tetrahydro-1,6-dialkyl-3,4-trimethylene-6aλ4-thia-1,3,4,6-tetraazapentalene-2,5-dithiones (1), which contain a hypervalent sulfur atom, have been found to give novel complexes by treating with Pt(PPh3)4 and Pd(PPh3)4. X-Ray investigations have revealed that the resultant complexes are novel metal–carbene complexes: {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(methylimino)methanethiolato-κ2SS′]}(triphenylphosphine)platinum(II) (2a), {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(ethylimino)methanethiolato-κ2SS′]}(triphenylphosphine)platinum(II) (2b), {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(methylimino)methanethiolato-κ2SS′ ]}(triphenylphosphine)palladium(II) (3a), {1,1′-(perhydropyrimidine-1,3-diyl-κC2)bis[(4-chlorophenylimino)methanethiolato-κ2SS′]}(triphenylphosphine)palladium(II) (3c). The central sulfur atom in 1 was substituted by a metal atom and thioamide groups rotated to form metal–sulfur bonds in the resultant metallapentalene framework. The Pt and Pd atoms are four-coordinated by two S atoms, a C atom and a P atom in a square-planar configuration. The metallapentalene framework in each complex is planar. The R values are 0.042, 0.029, 0.046, and 0.054 for 4114, 5849, 5005, and 7106 observed reflections for 2a, 2b, 3a, and 3c, respectively.
Crystal and Molecular Structures of Novel Metal–Carbene Complexes III. Rh–Carbene Complexes and Cu Complex
Authors: Iwasaki Fujiko , Yasui Masanori , Yoshida Satoshi , Nishiyama Hideyuki , Shimamoto Souichi , Matsumura Noboru 
Published: June 2006

Abstract
2,3,4,5-Tetrahydro-1,6-dialkyl-3,4-trimethylene-6aλ4-thia-1,3,4,6-tetraazapentalene-2,5-dithiones (1), which contain a hypervalent sulfur atom, have been found to give novel metal–carbene complexes by treating with RhCl(PPh3)3. X-Ray investigations have revealed that the resultant complexes are novel Rh–carbene complexes: trans(P,P′)-(chloro){[3-(methylthiocarbamoyl-κN)perhydropyrimidine-1-yl-κC2](methyliminomethanethiolato-κS)}-bis(triphenylphosphine)rhodium(III) (4a) and trans(P,P′)-(chloro){(perhydropyrimidine-1,3-diyl-κC2)bis[(4-chlorophenylimino)methanethiolato-κ2SS′]}bis(triphenylphosphine)rhodium(III) (4c). In these complexes, the central sulfur atom in 1 was substituted by a Rh atom. In 4a, obtained from 1,6-dimethyl-pentalene (1a), only one of the sulfur atoms of the thioamide groups coordinates the Rh atom, while the other thioamide group coordinates Rh with the N atom. Rh is coordinated by S, N, C, and Cl atoms to form an equatorial plane, and is coordinated by two PPh3 groups axially. In 4c, obtained from the 4-chlorophenyl derivative (1c), two thioamide groups rotated to form an S–Rh–S bond. A reaction of 1a with Cu(ClO4)2 gave a different kind of complex, bis (2,3,4,5-tetrahydro-1,6-dimethyl-3,4-trimethylene-6aλ4-thia-1,3,4,6-tetraazapentalene-2,5-dithione-κ2S4)copper(I) (7). The framework of the starting tetraazathiapentalene 1 remained unsubstituted, and the sulfur atoms of the thiocarbonyl groups of 1 coordinated the Cu atom to form one-dimensional coordination polymers, where the Cu atom is coordinated tetrahedrally by four S atoms. Because of a difference in the changes of the oxidation numbers of the metals during the reactions, metal–carbene complexes could not be obtained in the case of the Cu-complex.
Hydration of N,N-Bis(2-ethylhexyl)hexanamide in Dodecane
Authors: Naganawa Hirochika , Ohta Yasuo , Tachimori Shoichi 
Published: June 2006

Abstract
The hydration and dimerization of N,N-bis(2-ethylhexyl) hexanamide (BEHHA) in dodecane were studied on the basis of the water distribution between aqueous solutions and dodecane. The data obtained at 298 K were analyzed as functions of the amide concentration in the organic phase and the water activity in the aqueous phase. When the amide was monomeric in the organic phase, only a monohydrate was formed. At high amide concentrations in the organic phase, dimerization of the monohydrate occurred and (BEHHA)2(H2O)2 was formed. No other dimer hydrates were found in the organic phase. The results were compared with those of tributyl phosphate (TBP). The stoichiometry between BEHHA and water was investigated from low to very high amide concentrations in dodecane. The change in the activity coefficient for an amide contained in an inert solvent at high concentrations was also examined.
Studies of {[1](1,1′)Ferroceno[1](1,1′)ruthenocenophane}-1-ylium Hexafluorophosphate and Related α-Carbonium Salts
Authors: Watanabe Masanobu , Motoyama Izumi , Takayama Toshio 
Published: June 2006

Abstract
The oxidation of [1](1,1′)ferroceno[1](1,1′)ruthenocenophane ([1.1]FcRc) and ferrocenylruthenocenylmethane (FcCH2Rc) with bromo- or chlorobis(η5-cyclopentadienyl)ruthenocenium(1+) hexafluorophosphates gave the title compound, [Fe(C5H4CH2C5H4)(C5H4CH+C5H4)Ru]PF6− (1), as an α-carbonium salt and ferrocenylruthenocenylmethylium+ hexafluorophosphate [FeCp(C5H4CH+C5H4)CpRu]PF6− (3), respectively. The crystal of 1 has been found to be triclinic, space group , a = 10.572(9), b = 10.581(3), c = 9.680(5) Å, α = 99.50(3)°, β = 108.14(5)°, γ = 88.30(5)°, Z = 2, and the final R = 0.082 and Rw = 0.094. The distance between the Ru and Fe is 4.507(3) Å; which is much shorter than the value of neutral [1.1]FcRc one (4.792(2) Å). The two C5H4-rings in the Rc moiety are tilted largely (the tilting angle is 10.74°) due to a strong Ru···Cα (α-metylium) interaction. The crystal of 3 has been found to be orthorhombic, space group Pbca, a = 17.062(5), b = 19.172(6), c = 12.580(7) Å, Z = 8, and the final R = 0.067 and Rw = 0.072. The tilting angle of the Rc moiety is 7.98°. The most interesting difference between 1 and 3 is found in the distance between the Ru and Cα atoms; i.e., the distance of 3 (2.43(2) Å, closer to the Ru–C covalent bond) is significantly shorter than the value of 1 (2.51(1) Å, somewhat longer to the covalent bond); therefore, the greater positive –CH+– charge can be stabilized by a delocalization of the charge over the [RuCp(C5H4CH)]+ fragment for 3. However, the –CH+– charge is spread out over [Fe(C5H4CHC5H4)(C5H4CH2C5H4)Ru]+ for 1. Temperature-dependent 57Fe-Mössbauer spectroscopy (areal intensity ratio of ferrocene and ferrocenium) supports above the conclusion.
Low-Water-Content Diazomethane-d2 and Its Isotopic Assay
Authors: Strazzolini Paolo , Giumanini Angelo G , Verardo Giancarlo 
Published: June 2006

Abstract
A multiple D2O–CH2N2 exchange followed by a final anhydrification with K2CO3 gave an alcohol-free low-water-content ether solution of CD2N2. Procedural improvements for the exchange are reported. The extent of deuteration with a quantitative evaluation of the actual species present in any solution of diazomethane could be determined by a GC-MS analysis and 1H NMR spectrometry on a suitable derivative. In addition, a procedure for the quantitative determination of water in diazomethane solutions has been developed.
Comparison of biomarker strategies for rapid rule out of myocardial infarction in the emergency department using ACC/ESC diagnostic criteria
Authors: Collinson Paul O , Gaze David C , Morris Francis , Morris Brian , Price Alan , Goodacre Steve 
Published: June 2006

Objective: Creatine kinase MB isoenzyme (CK-MB) mass and rate of change of CK-MB have been proposed as superior to cardiac troponin measurement for very early exclusion of acute myocardial infarction (AMI). All three markers were examined prospectively in patients presenting to the Emergency Department (ED) for rule out of AMI. Methods: Consecutive admissions to the ED with undifferentiated chest pain were initially assessed clinically and by electrocardiography. A total of 786 patients (490 male, median age 52.5 years) considered at low risk of AMI had blood drawn on admission. If the first sample was less than 12 h from onset of chest pain, a second sample was then drawn at least 2 h later and at least 6 h from onset of chest pain. CK-MB mass was measured on the first sample and CK-MB mass and cardiac troponin T (cTnT) were measured on the second sample. Measurement of cTnT was using an Elecsys 2010 with the third generation assay (Roche Diagnostics, Lewes, UK). Assay coefficient of variation (CV) was 5.8% and 5.7% at 0.47 and 11.5 µg/L, respectively, with measuring range 0.01-25.0 µg/L; analytical sensitivity of 0.01 µg/L and functional sensitivity of 0.03 µg/L. CK-MB (mass) was measured by electrochemiluminesence using an Elecsys 2010 (Roche Diagnostics). The assay CV was 4.0% at 5.89 µg/L and 4.1% at 60.5 µg/L, with a detection limit of 0.1 µg/L and an upper measuring limit of 500 µg/L. Myocardial infarction was diagnosed if either sample had a CK-MB of more than 5 µg/L, if there was a change in CK-MB (∆CK-MB) of more than 1.5 µg/L or if the cTnT was more than 0.05 µg/L. When AMI was excluded, patients proceeded to stress electrocardiography and reattended 72 h from presentation for follow up phlebotomy for cTnT measurement. A final diagnosis of AMI was made according to American College of Cardiology/ European Society of Cardiology criteria using a cut-off of 0.05 μg/L cTnT in any of the samples. Diagnostic efficiency was compared by receiver operator characteristic (ROC) curve analysis with comparison of area under the curve (AUC) for four strategies: admission CK-MB measurement; 6-h post-pain CK-MB measurement; ∆CK-MB; and 6-h post-pain cTnT measurement. Results: On admission the AUC for CK-MB was 0.830 (95% confidence interval [CI] 0.757-0.904). At 6 h post pain the respective values were: CK-MB 0.939 (95% CI 0.889-0.988); -CK-MB 0.948 (95% CI 0.906-0.990); and cTnT 0.989 (95% CI 0.966-1.0). Conclusion: cTnT at 6 h has high diagnostic sensitivity for AMI and is superior to CK-MB mass and ∆CK-MB even using a low cut-off value.
Circadian rhythm of urinary steroid metabolites
Authors: Jerjes Walid K , Cleare Anthony J , Peters Timothy J , Taylor Norman F 
Published: June 2006

Background: Samples submitted for urinary steroid profile analysis are often untimed, but influence of collection time on interpretation is unknown. We report circadian rhythms of the major steroid metabolites and derived ratios in urine collected at 3-h intervals over 24 h, after first establishing that disturbance of sleep associated with collection does not alter rhythms on the succeeding day. Methods: Assay of steroid metabolites (gas chromatography) and creatinine in urine collections made by 10 men and 10 women every 3 h starting at 2100 for 24 h. Data were subjected to cosinor analysis. Results: Summed cortisol and androgen metabolites exhibited significant circadian rhythms, as expected, but with a surprisingly long time-lag (maxima at around 1400). Amplitudes were different, so that the ratio cortisol/androgen metabolites also showed a significant rhythm. The ratios 5 α/5 β tetrahydrocortisol and 20-hydroxy/20-oxo cortisol metabolites showed significant rhythms which were not in phase with total cortisol metabolites, while 11-hydroxy/11-oxo cortisol metabolites showed no rhythm. There were no gender differences in time of maxima. Previously established gender differences in metabolite levels were confirmed. Creatinine levels showed no circadian rhythm. Conclusion: Circadian variation should be considered when interpreting results from urine steroid analysis. Calculation of steroid/steroid or steroid/creatinine ratios is not informative in untimed collections.
Comparison of two prediction equations with radionuclide glomerular filtration rate: validation in routine use
Authors: Saleem Mohamed , Florkowski Christopher M , George Peter M , Woltersdorf Wolfram W W 
Published: June 2006

Background: Recent guidelines recommend automatic reporting of estimated glomerular filtration rate (eGFR) using the abbreviated Modification of Diet in Renal Disease (MDRD) equation with every request for plasma creatinine. We evaluated the performance of the MDRD and Cockcroft-Gault equations in routine use compared with a radionuclide GFR method. Method: Data collected on 601 patients aged 16-85 years who had undergone radionuclide GFR and eGFR was calculated using both equations for each patient. Calculations of bias, correlation coefficients and percentage estimates within 30% and 50% of radionuclide GFR were used in comparisons. Results: Overall, there was no significant difference in the performance between the two equations when compared with radionuclide GFR. When all creatinine results <60 μmol/L were adjusted to 60 μmol/L, and when creatinine results <60 μmol/L were excluded, MDRD performed better than the Cockcroft-Gault equation. MDRD was also superior for prediction of radionuclide GFR of <60 mL/min/1.73 m2 ( P=0.014). Conclusion: The abbreviated MDRD formula for eGFR is superior to the Cockcroft-Gault equation for prediction of radionuclide GFR of <60 μL/min/1.73 m2and is more accurate when creatinine results <60 μmol/L are either corrected to 60 μmol/L or excluded from eGFR calculations.
Urinary gonadotropin measurements in neonates: a valuable non-invasive method
Authors: Kuijper E A M , Houwink E J F , van Weissenbruch M M , Heij H A , Blankenstein M A , Huijser J , Martens F , Lambalk C B 
Published: June 2006

Background: To measure low neonatal gonadotropin levels, a sensitive non-invasive method is optimal. The aim of the current study was to validate the Architect i2000SR, an automated immunoassay analyser for the measurement of gonadotropins in unextracted neonatal urine samples against serum gonadotropin levels as a gold standard. Methods: Blood and urine were sampled from 30 approximately six-week-old male and female neonates undergoing elective paediatric surgery. Follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured and the urine results were corrected for creatinine. Results: The agreement between neonatal serum and urinary FSH was 0.904 (3-5 h between samples) and 0.704 (18-20 h). For LH, the correlation coefficients were 0.785 and 0.507, respectively. Conclusion: We conclude that gonadotropins can be reliably measured using the Architect on randomly voided, non-extracted urine samples collected from neonates by an adhesive device. Urinary gonadotropin levels are a proper reflection of the serum levels.
Predictors of elevated cardiac troponin T on admission in ST-segment elevation myocardial infarction
Authors: Rasoul Saman , Nienhuis Mark B , Ottervanger Jan Paul , Slingerland Robbert J , de Boer Menko-Jan , Dambrink Jan-Henk E , Ernst Nicolette M , Hoorntje Jan C A , Gosselink A T Marcel , Suryapranata Harry , Zijlstra Felix , van't Hof Arnoud W J 
Published: June 2006

Background: In patients with ST-segment elevation acute myocardial infarction (STEMI), elevated cardiac troponin T (cTnT) on admission is associated with poorer outcomes despite early reperfusion. Presentation delay is thought to be the most important factor for the elevation of cTnT on admission. We evaluated presentation delay and other potential predictors of elevated cTnT on admission in patients treated with primary percutaneous coronary interventions (PCI) for STEMI. Methods: CTnT was measured upon arrival in the PCI centre in 444 patients with acute STEMI. An elevated cTnT was defined as > 0.05 μg/L. Results: The mean age was 61.7 years and patients were admitted at a median of 155 min after symptom onset. Almost 50% had an elevated cTnT on admission. Patients with a positive cTnT on admission were less likely to have successful primary PCI (87 versus 93%, P=0.048) and had significantly higher rates of one-year mortality (4.9 versus 1.3%, P=0.031). There was a significant association between presentation delay and the prevalence of elevated admission cTnT, but even patients with early presentation (<120 min after symptom onset) still had a high prevalence of elevated cTnT (33%). After multivariate analysis, apart from presentation delay, anterior MI location and higher age were independent predictors of elevated cTnT on admission. Conclusion: In patients with STEMI, the prevalence of elevated cTnT on admission is high, even in patients with early presentation. Independent predictors of elevated cTnT on admission are presentation delay, increasing age and anterior MI location.