bluuebunny/crossref_metadata_2025 huggingface dataset:
Sildenafil treatment for portopulmonary hypertension
Authors: Reichenberger F. , Voswinckel R. , Steveling E. , Enke B. , Kreckel A. , Olschewski H. , Grimminger F. , Seeger W. , Ghofrani H. A.
Published: June 2006

Portopulmonary hypertension (POPH) is regarded as a subtype of pulmonary arterial hypertension (PAH); however, established PAH therapies have not been evaluated for this condition.

The current authors treated 14 patients (four male, 10 female; mean (range) age 55 (39–75) yrs) with moderate (n = 1) or severe (n = 13) POPH caused by alcoholic liver disease (n = 7), chronic viral hepatitis (n = 3), autoimmune hepatitis (n = 3), and hepatic manifestation of hereditary haemorrhagic teleangiectasia (n = 1) with oral sildenafil. Eight patients were newly started on pulmonary vasoactive treatment, while six patients were already on treatment with inhaled prostanoids (iloprost, n = 5; treprostinil, n = 1). During treatment with sildenafil, mean±sd6-min walk distance increased from 312±111 m to 397±99 m after 3 months, and 407±97 m after 12 months. Mean±sdpro-brain natriuretic peptide levels decreased from 582±315 ng·mL-1to 230±278 ng·mL-1, and to 189±274ng·mL-1after 3 and 12 months, respectively. Two patients died after 1 and 2 months from liver failure and cardiac failure, respectively. There was a similar response to sildenafil treatment after 3 and 12 months in patients on monotherapy and those on combination therapy.

In conclusion, sildenafil might be effective in monotherapy and in combination therapy with inhaled prostanoids in portopulmonary hypertension, leading to significant improvement by 3 months and sustained response over 12 months.
Healthcare workers with tuberculosis infected during work
Authors: de Vries G. , Šebek M. M. G. G. , Lambregts-van Weezenbeek C. S. B.
Published: June 2006

The risk for healthcare workers (HCWs) of tuberculosis (TB) attributable to occupational exposure is difficult to determine, as are the conditions contributing to this risk. The objective of the present study was to determine which TB cases among HCWs in the Netherlands were infected during work and to analyse factors which contributed to infection and subsequent disease.

The total study population consisted of 101 cases over a 5-yr period. In 67 (66%) subjects the route of infection could be determined by epidemiological and microbiological information. Of these cases, 28 out of 67 (42%) were due to infection at work, 19 (28%) were community acquired, and 20 (30%) were infected abroad.

The 28 cases infected at work were subject to an in-depth analysis. Delayed diagnosis of the index case, especially in the elderly patient, was the main cause of patient-to-HCW transmission. In some circumstances, inadequate infection-control measures also contributed to transmission.

In conclusion, a high suspicion of tuberculosis by the clinician, adequate infection control measures by hospital authorities, and early identification of latent tuberculosis infection by occupational and public-health specialists are necessary to prevent tuberculosis among healthcare workers.
Anti-inflammatory cytokines in cystic fibrosis lung disease
Authors: Starosta V. , Ratjen F. , Rietschel E. , Paul K. , Griese M.
Published: June 2006

Lung inflammation plays a pivotal role in the pathogenesis of airway disease in cystic fibrosis (CF). An imbalance between pro- and anti-inflammatory mediators has been observed and a deficiency in the anti-inflammatory response has been proposed, but this concept remains controversial.

In the present study, the concentrations of two anti-inflammatory mediators, lipoxin A (LxA4) and Clara cell protein 10 (CC-10), were assessed in bronchoalveolar lavage fluid (BALF) of CF patients with a wide range of endobronchial inflammation and disease controls with neutrophilic inflammation unrelated to CF.

No differences were observed in LxA4BALF concentrations between CF patients and controls with a similar degree of neutrophilic airway inflammation. Concentrations were also similar in CF patients with mildversusmore severe airway inflammation. In contrast, CC-10 concentrations were lower in CF patients, but this decrease was limited to patients with more intense airway inflammation.

The present data do not support the concept of a primary defect in anti-inflammatory mediators in cystic fibrosis lung disease. Although Clara cell protein concentrations were found to be reduced, these alterations appear to be secondary to neutrophilic airway inflammation rather than due to a primary deficiency.
Endobronchial ultrasound-guided transbronchial needle aspiration of lymph nodes in the radiologically normal mediastinum
Authors: Herth F. J. F. , Ernst A. , Eberhardt R. , Vilmann P. , Dienemann H. , Krasnik M.
Published: June 2006

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) can sample enlarged mediastinal lymph nodes in patients with nonsmall cell lung cancer (NSCLC). To date, EBUS-TBNA has only been used to sample nodes visible on computed tomography (CT). The aim of the present study was to determine the accuracy of EBUS-TBNA in sampling nodes ≤1 cm in diameter.

NSCLC patients with CT scans showing no enlarged lymph nodes (no node >1 cm) in the mediastinum underwent EBUS-TBNA. Identifiable lymph nodes at locations 2r, 2l, 4r, 4l, 7, 10r, 10l, 11r and 11l were aspirated. All patients underwent subsequent surgical staging. Diagnoses based on aspiration results were compared with those based on surgical results.

In 100 patients (mean age 58.9 yrs; 68 males), 119 lymph nodes ranging 5–10 mm in size were detected and sampled. Malignancy was detected in 19 patients but missed in two; all diagnoses were confirmed by surgical findings. The mean diameter of the punctured lymph nodes was 8.1 mm. The sensitivity of EBUS-TBNA for detecting malignancy was 92.3%, specificity was 100%, and the negative predictive value was 96.3%. No complications occurred.

In conclusion, endobronchial ultrasound-guided transbronchial needle aspiration can accurately sample even small mediastinal nodes, therefore avoiding unnecessary surgical exploration in one out of six patients who have no computed tomography evidence of mediastinal disease. Potentially operable patients with no signs of mediastinal involvement on computed tomography may benefit from pre-surgical endobronchial ultrasound-guided transbronchial needle aspiration and staging.
Physical activity is independently related to aerobic capacity in cystic fibrosis
Authors: Hebestreit H. , Kieser S. , Rüdiger S. , Schenk T. , Junge S. , Hebestreit A. , Ballmann M. , Posselt H-G. , Kriemler S.
Published: June 2006

It is unclear whether a relationship between physical activity (PA) and maximal oxygen uptake (V′O2,max) exists in cystic fibrosis (CF) and, if so, whether the relationship reflects a direct effect or is mediated by the effects of confounding variables, such as pulmonary or muscle function. The objective of the present study was to determine the relationship between PA andV′O2,maxin CF while adjusting for possible influences of confounding factors.

In total, 36 female and 35 male patients with CF from Germany and Switzerland (aged 12–40 yrs, forced expiratory volume in one second (FEV1) 25–107% predicted) were studied. A Wingate test was employed to measure muscle power. PA was monitored for 7 days and expressed in two ways: 1) average daily accelerometer count (ADAC) and 2) time spent in moderate-to-vigorous PA (MVPA).V′O2,maxwas determined during an incremental cycle exercise test to volitional fatigue.

PA was positively related toV′O2,max. In a multiple linear regression analysis, height, sex, FEV1, muscle power and ADAC (additionally explained variance 2.5%) or time spent in MVPA (additionally explained variance 3.7%) were identified as independent predictors ofV′O2,max.

In conclusion, high levels of physical activity in addition to good muscular and pulmonary functions are associated with a high aerobic capacity in cystic fibrosis.
Nontuberculous mycobacteria in bronchiectasis: prevalence and patient characteristics
Authors: Fowler S. J. , French J. , Screaton N. J. , Foweraker J. , Condliffe A. , Haworth C. S. , Exley A. R. , Bilton D.
Published: June 2006

The aim of the current study was to investigate the prevalence and clinical associations of nontuberculous mycobacteria (NTM) in a well-characterised cohort of patients with adult-onset bronchiectasis.

The sputum of all patients attending a tertiary referral bronchiectasis clinic between April 2002 and August 2003 was examined for mycobacteria as part of an extensive diagnostic work-up. NTM-positive patients subsequently had further sputa examined. A modified bronchiectasis scoring system was applied to all high-resolution computed tomography (HRCT) scans from NTM-positive patients, and a matched cohort without NTM.

Out of 98 patients attending the clinic, 10 had NTM in their sputum on first culture; of those, eight provided multiple positive cultures. Three patients were treated for NTM infection. A higher proportion of NTM-positive than -negative patients were subsequently diagnosed with cystic fibrosis (two out of nineversustwo out of 75). On HRCT scoring, more patients in the NTM-positive group had peripheral mucus plugging than in the NTM-negative group.

In the current prospective study of a large cohort of patients with bronchiectasis, 10% cultured positive for nontuberculous mycobacteria in a random clinic sputum sample. Few clinical parameters were helpful in discriminating between groups, except for a higher prevalence of previously undiagnosed cystic fibrosis and of peripheral mucus plugging on high-resolution computed tomography in the nontuberculous mycobacteria group.
Potential misclassification of causes of death from COPD
Authors: Jensen H. H. , Godtfredsen N. S. , Lange P. , Vestbo J.
Published: June 2006

Little is known about causes of death in chronic obstructive pulmonary disease (COPD) and the validity of mortality statistics in COPD. The present authors examined causes of death using data from the Copenhagen City Heart Study.

Of the 12,979 subjects with sufficient data from the baseline examination during 1976–1978, 6,709 died before 2001. Of these, 242 died with COPD as cause of death. Among subjects with at least severe COPD at baseline, only 24.9% had COPD as cause of death and, in almost half of the cases where COPD was listed as cause of death, the subject had a normal forced expiratory volume in one second /forced vital capacity ratio at baseline.

In COPD patients, having COPD on the death certificate was associated with chronic mucus hypersecretion (CMH) at baseline, an odds ratio (OR) of 3.6 (95% confidence interval 1.7–7.7), and being female (OR 2.7 (1.3–5.6)). In subjects without COPD, CMH and smoking were predictors of COPD as underlying cause of death, ORs 2.3 (1.5–3.7) and 2.2 (1.4–3.6), respectively.

It was concluded that chronic obstructive pulmonary disease is underreported on death certificates, that biases in the use of chronic obstructive pulmonary disease as cause of death can be assessed, and that possible “over-diagnosis” of chronic obstructive pulmonary disease on death certificates in subjects unlikely to have significant disease should initiate caution when using causes of mortality in chronic obstructive pulmonary disease epidemiology.
System Complexity As a Measure of Safe Capacity for the Emergency Department
Authors: France Daniel J. , Levin Scott
Published: June 2006

Objectives

System complexity is introduced as a new measure of system state for the emergency department (ED). In its original form, the measure quantifies the uncertainty of demands on system resources. For application in the ED, the measure is being modified to quantify both workload and uncertainty to produce a single integrated measure of system state.

Methods

Complexity is quantified using an information‐theoretic or entropic approach developed in manufacturing and operations research. In its original form, complexity is calculated on the basis of four system parameters: 1) the number of resources (clinicians and processing entities such as radiology and laboratory systems), 2) the number of possible work states for each resource, 3) the probability that a resource is in a particular work state, and 4) the probability of queue changes (i.e., where a queue is defined by the number of patients or patient orders being managed by a resource) during a specified time period.

Results

An example is presented to demonstrate how complexity is calculated and interpreted for a simple system composed of three resources (i.e., emergency physicians) managing varying patient loads. The example shows that variation in physician work states and patient queues produces different scores of complexity for each physician. It also illustrates how complexity and workload differ.

Conclusions

System complexity is a viable and technically feasible measurement for monitoring and managing surge capacity in the ED.
Surge Capacity Associated with Restrictions on Nonurgent Hospital Utilization and Expected Admissions during an Influenza Pandemic: Lessons from the Toronto Severe Acute Respiratory Syndrome Outbreak
Authors: Schull Michael J. , Stukel Therese A. , Vermeulen Marian J. , Guttmann Astrid , Zwarenstein Merrick
Published: June 2006

Background

Current influenza pandemic models predict a surge in influenza‐related hospitalizations in affected jurisdictions. One proposed strategy to increase hospital surge capacity is to restrict elective hospitalizations, yet the degree to which this measure would meet the anticipated is unknown.

Objectives

To compare the reduction in hospitalizations resulting from widespread nonurgent hospital admission restrictions during the Toronto severe acute respiratory syndrome (SARS) outbreak with the expected increase in admissions resulting from an influenza pandemic in Toronto.

Methods

The authors compared the expected influenza‐related hospitalizations in the first eight weeks of a mild, moderate, or severe pandemic with the actual reduction in the number of hospital admissions in Toronto, Ontario, during the first eight weeks of the SARS‐related restrictions.

Results

Influenza modeling for Toronto predicts that there will be 4,819, 8,032, or 11,245 influenza‐related admissions in the first eight weeks of a mild, moderate, or severe pandemic, respectively. In the first eight weeks of SARS‐related hospital admission restrictions, there were 3,654 fewer hospitalizations than expected in Toronto, representing a modest 12% decrease in the overall admission rate (a reduction of 1.40 admissions per 1,000 population). Therefore, influenza‐related admissions could exceed the reduction in admissions resulting from restricted hospital utilization by 1,165 to 7,591 patient admissions, depending on pandemic severity, which corresponds to an excess of 0.44 to 2.91 influenza‐related admissions per 1,000 population per eight weeks, and an increase of 4% to 25% in the overall number of admissions, when compared with nonpandemic conditions.

Conclusions

Pandemic modeling for Toronto suggests that influenza‐related admissions would exceed the reduction in hospitalizations seen during SARS‐related nonurgent hospital admission restrictions, even in a mild pandemic. Sufficient surge capacity in a pandemic will likely require the implementation of other measures, including possibly stricter implementation of hospital utilization restrictions.
Design of DNA-Cleaving Agents
Authors: Saito Isao , Nakatani Kazuhiko
Published: June 2006

The review focuses on the molecular design of artificial sequence-specific DNA-cleavers which have recently been developed in our laboratories. These include: DNA cleavers mimicking natural antitumor antibiotic like enediyne antibiotics, bleomycins, and kapurimycin A3. The design of photochemical DNA-cleaving molecules is also described. These are classified as: i) nonselective DNA cleavers, ii) thymine selective DNA cleavers, iii) photo-Fenton reagents, iv) photoinducible DNA alkylating agents, and v) DNA cleavers via photoinduced electrontransfer. The scope and limitation of these DNA-cleaving agents are described with a special emphasis on the concept and strategy for designing novel sequence-specific DNA cleavers, as well as on the mechanistic aspects of their DNA cleavage.
Derivative-State Analysis of a Sequential Intramolecular Vibrational Energy Re-distribution
Authors: Someda Kiyohiko
Published: June 2006

The Mori expansion adapted to pure-state dynamics is shown to be useful for analyzing a sequential intramolecular vibrational energy re-distribution (IVR). The expansion produces non-stationary basis states, “derivative states”, which form a chain of mutually interacting quantum states beginning at a given initial state. An analysis based on this chain clearly demonstrates how the Hilbert space of quantum states is explored in sequential IVR. The derivative states can be classified into several “generations”, and, thereby, a genealogy of quantum states can be discussed.
A Theoretical Study on the Oxidative Addition of a Si–H σ-Bond to [MCl(CO)(PH3)2] (M = Rh or Ir). Similarities to and Differences from [M′(PH3)2] (M′ = Pd or Pt) and [RhCl(PH3)2]
Authors: Sakaki Shigeyoshi , Ujino Yuka , Sugimoto Manabu
Published: June 2006

The Si–H Oxidative Addition to [MCl(CO) (PH3)2] (M = Rh or Ir) was theoretically investigated with ab initio MO/MP2—MP4, SD-CI, and CCD (coupled cluster with double substitutions) methods. This reaction proceeds with a somewhat high activation energy (Ea) and a moderate exothermicity (Eexo); when the oxidative addition occurs in the Cl–M–CO plane, Ea = 19 kcal mol−1 for Rh and 13 kcal mol−1 for Ir, and Eexo = 0.4 kcal mol−1 for Rh and 17.4 kcal mol−1 for M = Ir. This result is in significant contrast to [M′(PH3)2] (M′ = Pd or Pt) and [RhCl (PH3)2] : the Si–H oxidative addition occurs with a very small barrier for [M′(PH3)2], but a zero barrier and significantly high exothermicity for [RhCl(PH3)2]. The low reactivity of [MCl(CO)(PH3)2] is interpreted in terms of the low energy level of the d orbital, a considerable weakening of the M–Cl and M–CO bonds, and an exchange repulsion between SiH4 and the M d orbital in [MCl(CO)(PH3)2]. The above results indicate that Vaska-type complexes are less favorable for an oxidative addition reaction than [M′(PH3)2] and [RhCl(PH3)2], and that they cannot be used for a catalytic reaction including an oxidative addition which requires a high activation energy.
Mean Activity Coefficients of Simple Electrolytes in Polyelectrolyte Solutions
Authors: Kakehashi Rie
Published: June 2006

Mean activity coefficients of NaCl, NaNCS, or Na2SO4 were evaluated on the basis of the Donnan salt distribution in sodium polyacrylate (α = 0.3, 0.5, 0.8, and 1.0), sodium polystyrenesulfonate, poly(2-methacryloxyethyltrimethylammonium) chloride or polyallylamine hydrochloride solutions. Observed mean activity coefficients were close to those given by Manning’s limiting law (LL) at polyelectrolyte concentration me = 0.001 mol kg−1 in all systems examined. The observed activity coefficients showed large deviations from LL at high me and for Na2SO4 but they were in fair agreement with the theoretical values when corrected for the contribution from the small ion–small ion interaction.
High Pressure Raman Study of Hexafluorobenzene Crystals
Authors: Suzuki Yoshio , Shimada Hiroko , Shimada Ryoichi
Published: June 2006

Pressure effects on the Raman active inter- and intramolecular vibrations of hexafluorobenzene crystals were studied under hydrostatic pressures up to about 5 GPa at room temperature in a gasketed diamond anvil cell. The observed Raman spectra indicate that very gradual application of pressure to hexafluorobenzene liquid up to about 0.3 GPa gives rise to supercompressed liquid and the supercompressed liquid crystallizes in phase I by further successive applications of pressure. On the other hand, hexafluorobenzene liquid crystallizes in phase II by quick application of pressure up to about 0.8 GPa. The crystal structure in phase I grown via supercompression is unchanged up to about 2—4 GPa, depending on the experimental conditions and finally transfers to phase II. Coexistence of the crystal phases I and II gives complex spectral structures in both the inter- and intramolecular vibrational regions under various pressures. The pressure-induced frequency shift of the intermolecular vibrations of hexafluorobenzene crystal is compared with those of hexachloro- and hexabromobenzene crystals and it is shown that the repulsive force between the bromine atoms belonging to different molecules is stronger than the repulsive forces between the fluorine atoms and also between the chlorine atoms.
Stereostructural and Vibrational Analyses of cis-Polyacetylene Based on Density Functional Calculations of Oligoenes
Authors: Hirata So , Torii Hajime , Tasumi Mitsuo
Published: June 2006

The total energies and optimized structures of all-trans-transoid (Tt), all-cis-transoid (Ct), all-trans-cisoid (Tc), and all-cis-cisoid (Cc) oligoenes with various chain lengths were calculated using the Becke3–Lee–Yang–Parr (B3LYP) hybrid functional with the 6-31G* basis set. The optimized structures of the Tt and Ct oligoenes were found to be planer, whereas the Tc and Cc oligoenes have helical structures in which the conformations about the C–C bonds deviate from planar s-cis. The total energies of the Tt, Ct, Tc, and Cc oligoenes with the same chain length increase in this order. The vibrational force fields of the Ct and Tc oligoenes were calculated at the B3LYP/6-31G* level. The structures and force fields of the Ct and Tc polyacetylene were estimated by analyzing the chain-length dependence of the structural parameters and force constants of the oligoenes. The normal frequencies and the inelastic neutron scattering spectra were calculated for Ct and Tc polyacetylene on the basis of the thus-obtained structures and force fields. A comparison between the calculated and observed results clearly indicates that as-polymerized cis-rich polyacetylene consists of planar Ct chains. The comparison also suggests that the observed Raman bands of cis-rich polyacetylene films arise from Ct segments with intermediate conjugation lengths.
Reaction of 2-(Alkylthiomethyl)phenyllithium with Copper(I) Halides and Structure and Properties of One of the Products—Copper(I) Complexes of 2,2′-Bis(alkylthiomethyl)biphenyl
Authors: Toyota Shinji , Matsuda Yohei , Nagaoka Satoshi , Oki Michinori , Akashi Haruo
Published: June 2006

The title reactions did not afford the corresponding organocopper compound as a stable entity, but rather a dimerized biphenyl compound (2,2′-bis(alkylthiomethyl)biphenyl), its copper(I) halide complex, and alkyl benzyl sulfide. Their yields were influenced by the kind of halides in the copper reagent. The stability and reactivity of the intermediate organocopper compound is discussed on the basis of the ligand-metal interactions. The copper(I) halide complex with the biphenyl which carries two sulfane ligands has a unique polymeric structure in crystals, as evidenced by X-ray analysis, whereas it dissociates into a monomeric form on dissolution in organic solvents. The properties of the complexes were examined by NMR and XPS as well.
Stabilization of Oxo-Metal Bonding by the π-Conjugated System in Dithiolate Ligands: cis-Dioxotungsten(VI) Bis(naphthalenedithiolato) and the Related Complexes as Models for Tungsten Oxidoreductases
Authors: Oku Hiroyuki , Ueyama Norikazu , Nakamura Akira
Published: June 2006

As a model of tungsten oxidoreductase, a dioxotungsten(VI) dithiolato complex, (NEt4)2- [WVIO2(ndt)2]·H2O (1) (ndt = 2,3-naphthalenedithiolato), was synthesized. It has provided the detailed structural dimensions of mutual trans influence between oxo and thiolate. The complex, 1, crystallizes in space group P21/n with a = 7.396(2), b = 17.581(2), c = 28.839(2) Å, β = 95.35(2), and Z = 2, and was refined to R = 2.3%. The short S–C distances of the thiolate trans to the WVI=O groups indicate the presence of the partial double bonding at S–C (thiketone-like) which contributes to the stabilization of the dioxotungsten(VI) species by weakening π-interaction of the WVI–S bonds trans to the WVI=O groups. In the tungstopterin cofactor and the molybdopterin cofactor of the enzyme, the double bonding nature of S–C (thioketone-like) is expected to stabilize the oxo ligand of the tungsten and molybdenum ion.
Voltammetric Study on the Transport of Ions of Various Hydrophobicity Types through Bilayer Lipid Membranes Composed of Various Lipids
Authors: Shirai Osamu , Yoshida Yumi , Matsui Masakazu , Maeda Kohji , Kihara Sorin
Published: June 2006

The ion transport from one aqueous medium, W1, to another, W2, through a bilayer lipid membrane, BLM, was investigated voltammetrically by scanning the applied membrane potential, ΔVW1–W2, and monitoring the membrane current, IW1–W2. The shapes of voltammograms observed with a definite BLM depended on the hydrophobicity and the concentration of the ion added into W1 and/or W2, and can be classified into four types. The transport processes involved in each type of voltammogram were elucidated in the light of knowledge about ion transport processes through liquid membranes and by taking into account the conjugated ion transfers at interfaces of W1/BLM and BLM/W2. The shapes of voltammograms were also transformed when BLMs made of different lipids were employed. The spontaneous condensation of objective ions from W1 and/or W2 to the BLM by the partition with counter ions, which depends on the properties of objective ions, counter ions and lipids composing BLMs, is essential for the ion transport through BLMs.
Macrocyclic Polyazacycloalkane-poly-N-carboxylate Anion as a Receptor for Amino Acid
Authors: Kodama Mutsuo
Published: June 2006

The doubly-protonated 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetracarboxylate anion (H2teta2−), 1,4,7,10,13-pentaazacyclopentadecane-1,4,7,10,13-pentacarboxylate anion (H2pepa3−), and 1,4,7,10,13,16-hexaazacyclooctadecane-1,4,7,10,13,16-hexacarboxylate anion (H2heha4−) have been shown to form stable 1 : 1 ratio complexes with amino acids in aqueous solutions. Their association constants, βL, were determined polarographically. The greater association constants obtained indicate that H2teta2− and H2pepa3− anions selectively interact with an amino acid which has a planar aromatic moiety. The results show the importance of hydrophobic interaction, such as CH–π interaction between the aliphatic CH2 residue of acetate pendant of receptor and the planar aromatic moiety of substrate, amino acid, in holding the protonated macrocyclic polyazacycloalkane-poly-N-polycarboxylate anion and amino acid together. Thus, they act as selective receptors for phenylalanine, tyrosine, tryptophan(e), and their derivatives.
Copper(II) Complexes of 6-Amino-5,7-dioxo-1,4,8,11-tetraazacyclotetradecane
Authors: Kodama Mutsuo
Published: June 2006

A newly synthesized dioxocyclam ligand, 6-amino-5,7-dioxo-1,4,8,11-tetraazacyclotetradecane, reacts with copper(II) ions and forms a stable binuclear yellow complex, [Cu2H−2L]2+, as well as a mononuclear pink complex, [CuH−2L]°, in borate buffer solutions. Their formation equilibria were established by the pH-metric titration and spectrophotometric method. At the dropping mercury electrode the yellow copper(II) binuclear complex gave four reduction steps of equal height in a borate buffer solution, corresponding to the following reduction scheme:
Surfactant Extraction and Determination of Ruthenium(III) as a Thiocyanato Complex
Authors: Tagashira Shoji , Murakami Yoshiko , Nishiyama Miyuki , Harada Nobuko , Sasaki Yoshiaki
Published: June 2006

Ruthenium(III) was reacted to form a complex with thiocyanate, and extracted into the surfactant phase with Zephiramine (Z) by heating. The structure of this ion-pair was estimated to be [RuX2(SCN)2]−·Z+, in which X was a chloride ion, and was observed to cause an increasing absorbance and a blue shift of the spectrum. The determination of ruthenium(III) was investigated by the surfactant extraction-spectrophotometric method using a nonionic surfactant of Triton X-100 as an extraction solvent. The molar absorptivity was equal to 1.16 × 104 dm3 cm−1 mol−1 at 565 nm. Ruthenium(III) could be concentrated from the solution into a surfactant phase having a small volume. The first-order derivative spectroscopic method was used to reduce the interference from other platinum-group elements, such as osmium.
Interconversion between Polymeric Orange and Monomeric Green Forms of a Schiff Base-Oxovanadium(IV) Complex
Authors: Nakajima Kiyohiko , Kojima Masaaki , Azuma Shunryo , Kasahara Ryuichi , Tsuchimoto Masanobu , Kubozono Yoshihiro , Maeda Hironobu , Kashino Setsuo , Ohba Shigeru , Yoshikawa Yuzo , Fujita Junnosuke
Published: June 2006

The orange and green forms of the Schiff base-oxovanadium(IV) complex, [VO{sal-(RR)-stien}]·MeOH (1, green), [VO{sal-(RR)-stien}]·2CHCl3 (2, green), and [VO{sal-(RR)-stien}]·CH3CN (3, orange) (H2{sal-(RR)-stien} = N,N′-disalicylidene-(RR)-1,2-diphenyl-1,2-ethanediamine), have been prepared, and their crystal structures were determined by an X-ray method. The green forms, 1 and 2, contain mononuclear square pyramidal molecules of the complex, while the orange form 3 consists of individual complexes stacked to give an infinite linear ···V=O···V=O··· chain. 1, which crystallizes as monoclinic in space group P21 with Z = 4, has the cell parameters a = 16.684(2), b = 16.923(4), c = 9.249(3) Å, β = 105.76(2)°, and V = 2513(1) Å3. 2, which crystallizes as triclinic in space group P1 with Z = 2, has the cell parameters a = 13.187(3), b = 13.469(3), c = 10.450(3) Å, α = 103.72(2), β = 103.20(3), γ = 63.03(2)°, and V = 1591.2(7) Å3. 3 crystallizes as triclinic in space group P1 with Z = 2. The cell parameters are a = 13.300(3), b = 13.667(4), c = 7.551(1) Å, α = 90.44(2), β = 94.51(2), γ = 97.36(2)°, and V = 1357(1) Å3. The final R indices are R = 0.059 and RW = 0.062 for 1, R = 0.098 and RW = 0.090 for 2, and R = 0.053 and RW = 0.042 for 3. The structural characteristics of these complexes are compared and discussed. 3 shows piezochromism (mechanochromism); its color changes from orange to green upon grinding. 1 and 2 turn orange when heated at 120 °C for a few minutes. The extent of conversion either by grinding or heating was studied by EXAFS (X-ray absorption fine structure) and IR spectroscopy. The orange crystals turn green when exposed to chloroform vapor, and the green crystals turn orange upon exposure to acetonitrile vapor.
Multinuclear NMR Studies on Micellar Formation of Aqueous [Co(N-octyl- or N-dodecylethylenediamine)(3,7-Diazanonane-1,9-diamine)]3+ Solutions
Authors: Iida Masayasu , Yamamoto Mizuho , Fujita Naoko
Published: June 2006

The aggregation of [Co(R-en)(2,3,2-tet)]X3 (R-en = N-octyl- or N-dodecylethylenediamine, 2,3,2-tet = 3,7-diazanonane-1,9-diamine, and X = Cl or ClO4) in water was investigated by 59Co, 35Cl, 35ClO4, 2H2O, and 1H NMR measurements. NMR parameters, such as the relaxation rates and linewidths for the 59Co and 35Cl nuclei, were appreciably changed by micellar formation. We determined the CMC (critical micelle concentration) values (0.12 mol kg−1 for the octyl complex perchlorate, 0.008 mol kg−1 for the dodecyl perchlorate, and 0.010 mol kg−1 for its chloride) by measuring the NMR relaxations. The obtained CMC values are much larger than those previously reported on these surfactants, and are comparable to those of monovalent surfactants having the same alkyl-chain length. The aggregation of [Co(dod-en)(2,3,2-tet)]X3 (X = Cl or ClO4) in aqueous solution was also measured using vapor-pressure osmometry; the result supports the formation of ion aggregates at the CMCs, which was determined by NMR measurements. The 35Cl NMR measurements indicate that the interaction of the chloride counter ion with the dodecyl complex ion was appreciably larger than that with the dodecyltrimethylammonium ion at concentrations even below CMC. The effect of the trivalent positive charge of the cobalt(III) surfactant on the CMC value may be attenuated by the large size of the head group. A characteristic downfield shift of the 59Co resonance was observed due to the formation of micelles.
Stereoselective Syntheses of α-Glucuronides Using Dehydrative Glycosylation
Authors: Koto Shinkiti , Miura Teruhisa , Hirooka Motoko , Tomaru Aya , Iida Mika , Kanemitsu Masanori , Takenaka Kazuhiro , Masuzawa Shinichi , Miyaji Saeko , Kuroyanagi Naoko , Yagishita Miki , Zen Shonosuke , Yago Kazuo , Tomonaga Fumiya
Published: June 2006

Methyl and benzyl 2,3,4-tri-O-benzyl-d-glucopyranuronates, prepared from d-glucurono-6,3-lactone, afforded selectively the corresponding α-glucopyranosiduronates by the aid of the condensing reagent system composed of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine. Using this method, O-α-d-glucopyranuronosyl-(1→3)-O-α-l-arabinofuranosyl-(1→3)-d-xylopyranose, one of the minimal component units in the structure of plantago-mucilage A from the seeds of Plantago asiatica Linné constituting a Chinese medicine : chegianzi [].
Buffer Catalysis of the Hydrolysis of Phenyl and Methyl Benzenesulfinates. Contrasting Behavior between Acyclic and Cyclic Analogs
Authors: Okuyama Tadashi
Published: June 2006

The hydrolysis of phenyl benzenesulfinate is catalyzed by both acid and base, and is strongly accelerated by the carboxylate and amine base components of the buffer. Carboxylates and amines constitute different groups in the Brønsted plots, falling nearly on two separate lines of β = 1. The carboxylates are about 400-times more effective catalysts than the amines of similar basicity. Solvent deuterium isotope effects on the catalytic constants are small, and the buffer catalysis is considered to be nucleophilic. By contrast, the hydrolysis of the methyl ester was only weakly affected by the buffer, if at all. High efficiencies of oxygen nucleophiles in the catalysis of the hydrolysis of acyclic sulfinates are distinctive compared with the cyclic analogs, and are rationalized by a concerted SN2-like mechanism of the nucleophilic reaction at sulfur.
Formation of 5-Alkoxy-2-aminooxazoles and Their Novel Reactivity: Equilibrium with Nitrile Ylide
Authors: Fukushima Kazuaki , Lu Yue-Qin , Ibata Toshikazu
Published: June 2006

The Rh2(OAc)4-catalyzed reactions of diazoacetates with diisopropylcyanamide gave 5-alkoxy-2-aminooxazoles. Their isolation was achieved by introduction of a bulky alkoxy group at 5-position. The 5-alkoxy-2-aminooxazole reacted with methanol to give a 1 : 1-adduct in a quantitative yield. The kinetic study indicates that this reaction proceeds in a stepwise mechanism including an equilibrium of the 5-alkoxy-2-aminooxazole with a nitrile ylide intermediate.
The Roles of 2- and 3-Axial Methoxy Groups in Determining the Stereochemistry of the Complex Metal Hydride Reduction of Cyclohexanones: Examination of the Cieplak Model
Authors: Senda Yasuhisa , Sakurai Hiroshi , Nakano Shigeru , Itoh Hiroki
Published: June 2006

The 2- and 3-axially substituted methoxy groups in cyclohexanones exhibit steric hindrance similar to that of the methyl group in LiAlH4 and NaBH4 reductions. The chelate complex formation between the zinc ion and the two oxygens in the molecule was suggested in the zinc borohydride reduction. The relative reactivities of cyclohexanones in which the 2-axial position is substituted by the methyl or the methoxy group in the LiAlH4 reduction strongly support Cieplak’s proposal, which focuses on the importance of the stabilization of the transition state by anti-periplanar allylic bonds.
Reactivity of trans-[M(CO)(DMF)(Ph2PCH2CH2PPh2)2] (M = Mo, W) toward Terminal Alkynes: Synthesis of Alkynylhydrido and Vinylidene Complexes
Authors: Nakamura Goh , Harada Yuji , Mizobe Yasushi , Hidai Masanobu
Published: June 2006

Treatment of trans-[Mo(CO)(DMF)(dppe)2] (1a; dppe = Ph2PCH2CH2PPh2) with HC≡CCOOMe in benzene at room temperature or at reflux afforded an alkynylhydrido complex [Mo(C≡CCOOMe)H(CO)(dppe)2] (4a), whereas the reactions of 1a with arylacetylenes HC≡CR in benzene at reflux resulted in the formation of vinylidene complexes cis-[Mo(=C=CHR)(CO)(dppe)2] (R = Ph (6a) or 4-MeC6H4). The W analogue trans-[W(CO)(DMF)(dppe)2] (1b) gave only alkynylhydrido complexes [W(C≡CR)H(CO)(dppe)2] (R = COOMe (4b) or Ph) by treatment with either HC≡CCOOMe or HC≡CPh. From the Mo vinylidene complex 6a was obtained an alkylidyne complex cis-[Mo(≡CCH2Ph)(CO)(dppe)2][BF4] (9a) upon treatment with aqueous HBF4, whereas the reactions of Mo and W alkynylhydrido complexes 4 with HBF4·Et2O also resulted in the formation of the alkylidyne complexes cis-[M(≡CCH2COOMe)(CO)(dppe)2][BF4] (10). The vinylidene complexes cis-[M(=C=CHCOOMe)(CO)(dppe)2] (11) were readily derived from 10 by the reactions with NaOMe; these were not accessible from direct treatment of 1 with HC≡CCOOMe. The detailed structures of 4a, 4b, 9a, and 11b (M = W) have been established by single-crystal X-ray analyses.
Synthesis of Cysteine-Containing Polypeptide Using a Peptide Thioester Containing a Cys(Acm) Residue
Authors: Kawakami Toru , Kogure Shuji , Aimoto Saburo
Published: June 2006

A method was developed for the preparation of a cysteine-containing polypeptide, using a Cys(Acm)-containing peptide thioester obtained by a Boc solid-phase method. To demonstrate the utility of the developed method, human adrenomedullin consisting of 52 amino acid residues was synthesized. A peptide thioester, Boc–[Cys(Acm)16]–adrenomedullin(1—19)-SCH2CH2CO-β-Ala–NH2, and [Cys(Acm)21, Lys(Boc)25,36,38,46]-adrenomedullin(20—52) were prepared by conventional solid-phase methods. These peptide segments were condensed in the presence of silver ions, an additive, and a base. When HOBt or HOOBt was used as an additive, the segment coupling proceeded with negligible decomposition of Acm groups to give the desired product. A method for the removal of S-Acm groups from cysteine residues under basic conditions in the presence of silver ions and water, is also described.
Reaction Mechanism of NO Reduction by CH4over Rare Earth Oxides in Oxidizing Atmosphere
Authors: Otsuka Kiyoshi , Zhang Qinghong , Yamanaka Ichiro , Tono Hiromi , Hatano Masaharu , Kinoshita Hiroo
Published: June 2006

Rare earth oxides have been examined as catalysts for the catalytic reduction of NO by CH4 in the presence of oxygen. Among the rare earth oxides examined, Sc2O3 and Sm2O3 were found to be active for this reaction. For the Sm2O3 catalyst, ZrO2 was the most effective support. The mechanism of the reaction was studied over the Sm2O3/ZrO2. Kinetic studies indicated that CH4 oxidation is initiated by O2, and NO can react only with CH3 radicals formed from the reaction of CH4 with O2. Ab-initio MO calculations also suggested that CH3 radical is a more favorable reducing species for selective reduction of NO than CH4. It is thus proposed that NO is reduced into N2 by the CH3 radical formed from the activation of methane by oxygen.
Raman Spectroscopy as a Useful Probe of Mechanisms of Deterioration of Metal Oxide Materials due to Laser Irradiation
Authors: Sato Hiroyasu , Nishio Satoru , Kato Shinobu , Marumo Kenji , Matsuzaki Akiyoshi , Yoshida Ryo
Published: June 2006

Raman spectroscopy provides a very useful means to study mechanisms of deterioration of metal oxide materials due to laser irradiation. Excimer laser irradiation (308 nm) induced transition of anatase of TiO2 to rutile, while it did not cause substantial changes for rutile or HfO2. The deterioration mechanism is essentially a thermal one, as supported by the morphological changes monitored by SEM measurements.
Micellar Rate Effects on Alkaline Hydrolysis of Hydroxamic Acids
Authors: Ghosh Kallol Kumar , Roy Supriya
Published: June 2006

The kinetics of alkaline hydrolysis of N-phenylbenzohydroxamic acid and its para-substituted derivatives (X–C6H4–CO–N(OH)C6H5; X = H, CH3, OCH3, NO2, F) have been investigated in the presence and absence of cationic (ethyl hexadecyl)dimethylammonium bromide) and anionic (sodium-1-dodecanesulfonate and lithium dodecyl sulfate) surfactants at 55 °C in 5% (v/v) dioxane–water medium. A catalytic effect was found with cationic surfactants and an inhibitory effect in the presence of anionic surfactants was observed. The rate-surfactant profiles can be analyzed in terms of pseudo-phase and Piszkiewicz models.
Effects of Metal Cations on the Dynamic Characteristics of a Phospholipid Thin Film at an Air/Water Interface
Authors: Makino Masakazu , Kamiya Mamoru , Ishii Toshio , Yoshikawa Kenichi
Published: June 2006

We measured the time-dependent surface pressure of a dioleoylphosphatidylcholine film at an air/water interface. Our results indicate that: (i) the surface pressure of the thin film traces a closed hysteresis loop accompanied by repetitive cycles of compression and expansion, and (ii) the area of the hysteresis loop markedly increases in the presence of sodium ions. We propose a kinetic model for this phenomenon which includes cooperative aggregation/dissociation at the air/water interface. The experimental findings have been successfully reproduced with the aid of a computer simulation based on this theoretical model.
Photocatalysis of H3PW12O40 for 4-Chlorophenol Decomposition in Aqueous Media
Authors: Einaga Hisahiro , Misono Makoto
Published: June 2006

Photocatalytic properties of PW12O403− (abbreviated as PW123−) for the 4-chlorophenol (4-CP) decomposition was investigated by using a 300 W Xe lamp at 35 °C in aqueous media. The rate of the 4-CP decomposition was not influenced by pH in the range from 1.0 to 2.0, where PW123− is stable. In the dark, no reaction proceeded. When the photolysis was carried out under O2 atmosphere, 4-CP was decomposed and the catalyst remained in the oxidized form. In the deaerated solution, PW123− was reduced to PW12O404− (PW124−) by irradiation, the amount of PW124− formed during irradiation being approximately identical with the amount of 4-CP concurrently consumed. When the irradiation was stopped and O2 was introduced, PW124− was oxidized rapidly to PW123− and a small amount of 4-CP decomposed.

Based on these facts we deduced that the reaction consists of the following three steps: (1) photoexcitation of PW123−, (2) one-electron reduction of the excited PW123− to PW124− with simultaneous oxidation of 4-CP, and (3) reoxidation of PW124− to the original form by O2. 4-CP is also decomposed in the last step, although the amount is much smaller than that in step (2). The dependency of the reaction rates on the concentration of substrate was explained by Langmuir (or Michaelis Menten) type kinetics, indicating that the complex formation between PW123− and 4-CP is the indispensable step of the photocatalytic decomposition.
Anomalous Magnetic Quenching of ortho-Positronium in Solutions of Nitrobenzene and 1,3-Dimethyl-2-nitrobenzene
Authors: Kobayashi Yoshinori , Hirata Kouichi
Published: June 2006

The magnetic quenching of ortho-positronium (o-Ps) has been studied for various solutions of nitrobenzene and 1,3-dimethyl-2-nitrobenzene. Static magnetic fields were applied to the solutions and the average o-Ps lifetimes were measured as a function of the field strength up to 1 T. Anomalous magnetic quenching, similar to that observed for nitrobenzene in hexane, was found for solutions of nitrobenzene in isopentane, pentane, diethyl ether and heptane as well as 1,3-dimethyl-2-nitrobenzene in dodecane and toluene. It is suggested that o-Ps detached from a weakly bound complex between positronium (Ps) and the nitrocompound may be responsible for the anomalous effect.
Electrochemical Behavior of Electrodes Modified with π-Conjugated Polymers in 0.5 M H2SO4 (aq) and 1 M KOH (aq) Electrolytes
Authors: Yamamoto Takakazu , Matsuzaki Takehiro , Minetomo Akiyuki , Kawazu Yoichi , Ohashi Osamu
Published: June 2006

Plantinum electrodes modified with 10 kinds of π-conjugated polymers have been prepared. These polymers include poly(pyridine-2,5-diyl) PPy, poly(2,2′-bipyridine-5,5′-diyl) PBpy, poly(3-octylthiophene-2,5-diyl) P3OcTh, and poly(6-hexylpyridine-2,5-diyl) P6HexPy. Films of PPy and PBpy behave as good H+-transporting materials in 0.5 M H2SO4 (aq). Plots of log i vs. V for electrodes modified with the polymers give linear lines in a current density region of 10−5.5—10−2 A cm−2. The slope of the line, β = dV/d(log i), depends on the kind of the polymer. Hydrophilic PPy and PBpy give a β value of 3.2 × 10−2 V, while hydrophobic P3OcTh and P6HexPy with long alkyl chains give a larger β value of 4.5 × 10−2 V. Diffusion coefficients of H+ in films of PPy, PBpy, and poly(quinoline-2,6-diyl) P(2,6-Q) are estimated to be larger than 10−7 cm2 s−1 from limiting currents at room temperature. The i–V curve of a P(2,6-Q)-modified Pt electrode shows a strong pH-dependence reflecting a chemical change of the polymer with pH. The PPy-, PBpy-, and P3OcTh-modified Pt electrodes exhibit acceleration effects for evolution of O2 from 1 M KOH (aq).
Chain Compounds of Rhodium(II) Trifluoroacetate Linked by p-Quinone [Rh2(O2CCF3)4(p-Q)]n, p-Q = 1,4-Benzoquinone, 1,4-Naphthoquinone, and 2,3-Dimethyl-1,4-benzoquinone
Authors: Handa Makoto , Mikuriya Masahiro , Sato Yuka , Kotera Takanori , Nukada Ryoji , Yoshioka Daisuke , Kasuga Kuninobu
Published: June 2006

A series of chain complexes of rhodium(II) trifluoroacetate, [Rh2(O2CCF3)4(p-Q)]n (p-Q = 1,4-benzoquinone (1,4-bq), 1,4-naphthoquinone (1,4-nq), and 2,3-dimethyl-1,4-benzoquinone (2,3-dmbq)) have been prepared. The chain structures were confirmed by the X-ray structure analyses. The carbonyl oxygens of the p-quinones are coordinated to the Rh2 centers with the distances of 2.248(5) (for p-Q = 1,4-bq), 2.248(3) (for p-Q = 1,4-nq), and 2.247(9) Å (for p-Q = 2,3-dmbq), respectively. The bridging mode of the p-quinone was discussed in relation to the substituent effect of CF3 group on the carboxylate.
Synthesis and Characterization of Thiolato-Bridged Trinuclear Heterometal Complexes with 2-[(3-Aminopropyl)amino]ethanethiol
Authors: Mikuriya Masahiro , Tsutsumi Hideyuki , Nukada Ryoji , Handa Makoto , Sayama Yasuyoshi
Published: June 2006

A series of ten trinuclear heterometal complexes with 2-[(3-aminopropyl)amino]ethanethiol (HL), [(MAL2)2MB](ClO4)2·2dmac·2X ([MA, MB] = [Mn, Zn], [Mn, Cd], [Fe, Zn], [Fe, Cd], [Fe, Hg], [Co, Zn] [Co, Cd], [Ni, Zn], [Ni, Cd], [Ni, Hg]; dmac = N,N-dimethylacetamide, X = H2O or CH3OH), have been synthesized and characterized by infrared and electronic spectroscopies, temperature dependence of magnetic susceptibilities (80—300 K), and single-crystal X-ray diffraction technique. Each complex has a thiolato-bridged heterotrinuclear structure which shows a linear arrangement of Oh(MA)–Td(MB)–Oh(MA). The spectral and magnetic properties were discussed in relation to the crystal structures.
Multielement Determination of Trace Elements in Sediment Sample by Inductively Coupled Plasma Mass Spectrometry with Microsampling Technique
Authors: Fujimori Eiji , Wei Rong , Sawatari Hideyuki , Chiba Koichi , Haraguchi Hiroki
Published: June 2006

A discrete microsampling technique for multielement determination of trace elements by inductively coupled plasma mass spectrometry has been investigated for analyses of samples containing large amounts of matrix elements. In the technique, 100 μl of the sample solution was introduced into the plasma by using a six-way valve, and 10 elements were detected in peak hopping mode during a single mass range scan. As a result, a transient peak profile of the signal for each element was observed at each m/z position. The peak area measurement method was established for the quantitative analysis. The optimization of instrumental conditions and matrix effects in multielement determination were investigated in detail. The discrete microsampling technique was found to reduce some memory effects due to matrices in ICP-MS. The present system was applied to the analyses of standard sediment sample and 30 elements at the μg g−1 level were successfully determined without matrix separation.