bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct chemiluminescence determination of ibuprofen by the enhancement of the KMnO4–sulphite reaction
Authors: Li Yinhuan , Lu Jiuru 
Published: April 2007

AbstractA simple, rapid, flow‐injection chemiluminescence (CL) method is described for the determination of ibuprofen. A strong CL signal was detected when a mixture of the analyte and sulphite was injected into acidic KMnO4. The CL signal is proportional to the concentration of ibuprofen in the range 0.1–10.0 mg/L. The detection limit is 0.02 mg/L ibuprofen, the relative standard deviation is 1.8% (0.5 mg/L ibuprofen; n = 11) and the sample measurement frequency is 120/h. The proposed method was successfully applied to the determination of ibuprofen in pharmaceutical preparations and in spiked urine samples. The mechanism of the CL reaction is also discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Quantitative determination of bilirubin by inhibition of chemiluminescence from lucigenin
Authors: Lee Hyun Sook , Karim Mohammad Mainul , Alam Seikh Mafiz , Lee Sang Hak 
Published: April 2007

AbstractBilirubin is a metabolic breakdown product of blood haem, of great biological and diagnostic importance. A new chemiluminescence (CL) method has been developed for the quantification of bilirubin. The method is combined with the flow injection analysis (FIA) technique and based on the inhibition effect of bilirubin on the CL from the lucigenin–hydrogen peroxide system in an alkaline medium. Under the optimum conditions, the decreased CL intensity was proportional to the concentration of bilirubin, in the range 0.0585–58.47 µg/mL. The detection limit estimated from the calibration graph was about 7.8826 ng/mL. The relative standard deviation (RSD) of 10 parallel measurements (1 × 10−4 mol/L bilirubin) was 2.5%. Recoveries of bilirubin were found to fall in the range 94–97.5% using control sera. The method is interference‐free, fast and easy to carry out. Copyright © 2007 John Wiley & Sons, Ltd.
Flow‐injection–electrochemical oxidation fluorimetry for determination of methotrexate
Authors: Chen Suming , Zhang Zhujun , He Deyong , Hu Yufei , Zheng Huzhi , He Chao 
Published: April 2007

AbstractA novel fluorimetric model of on‐line electrochemical oxidation for the determination of methotrexate (MTX) is described in this paper. The method was based on the oxidation of MTX to a highly fluorescent product, 2,4‐diaminopteridine‐6‐carboxylic acid, by constant potential in the electrochemical oxidation flow cell. Stopped‐flow techniques were employed. Under optimal conditions, the fluorescence intensity of 2,4‐diaminopteridine‐6‐carboxylic acid was measured at excitation and emission wavelengths of 380 and 465 nm, respectively. The calibration graph was linear over concentrations of methotrexate in the range 2.0 × 10−7–1.0 × 10−5 g/mL, with a detection limit of 5.2 × 10−8 g/mL (3σ). The method has been successfully applied to the determination of methotrexate in human urine samples and showed a percentage recovery in the range 94.3–102.5%. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of high‐temperature annealing on optical properties of porous anodic alumina formed in oxalic acid
Authors: Li Zhaojian , Huang Kelong 
Published: April 2007

AbstractPhotoluminescence (PL) of anodic alumina membranes (AAMs) with ordered nanopore arrays fabricated in oxalic acid has been investigated under different annealing temperatures. X‐ray diffraction reveals the structural transition from the amorphous state to crystallization. PL measurements show that a blue PL band occurs in the wavelength range 300–600 nm. The differential thermal analysis (DTA) and thermogravimetric analysis (TG) results revealed plentiful oxalic ions incorporated into the prepared AAMs. The PL band of AAMs could be attributed to the co‐actions of the oxygen vacancies (F+ and F centres) and the luminescent centres transformed from oxalic impurities. With the increase of the annealing temperature, the intensities of PL increase first, and at 500°C reach a maximum value, then decrease. The PL phenomenon is intimately related to the temperature‐induced structural transitions. There are three optical centres in the annealed AAMs; the first is originates from the F centres, the second is correlated with F+ centres and the third is associated with the oxalic impurities incorporated in the AAMs. Copyright © 2007 John Wiley & Sons, Ltd.
A flow‐injection chemiluminescence method for the determination of human serum albumin, using the reaction of fluorescein–human serum albumin–sodium hypochlorite by the enhancement effect of the cationic surfactant cetyltrimethylammonium bromide
Authors: Huang Chun‐Bao , Zhang Kai , Liu Xue‐Lian , Wang Sheng‐Fu 
Published: April 2007

AbstractThe interaction between surfactant and fluorescein was studied, using a fluorescence spectroscopy and flow‐injection (FI) chemiluminescence (CL) method. It was found that the cationic surfactant cetyltrimethylammonium bromide (CTAB) could cause the structural transformation of fluorescein from the quinone to the spirolactone form, and greatly enhance the CL intensity of the fluorescein–human serum albumin (HSA) complex. Based on this finding, a rapid and sensitive FI–CL method was developed for the determination of HSA. Under the optimum conditions, the proposed method has a linear range of 0.05–24.0 µg/mL, with a detection limit of 0.03 µg/mL for HSA (3σ). The relative standard deviation (RSD) of 1.2 µg/mL HSA (n = 8) is 0.8%. The method was applied to the determination of protein content in urine samples, with satisfactory results. Density functional theory was used to study the mechanism of surfactant‐enhanced CL intensity of the fluorescein–HSA complex. Copyright © 2007 John Wiley & Sons, Ltd.
A fluorimetric method for the determination of trace pentachlorophenol, based on its inhibitory effect on the redox reaction between the improved Fenton reagent and rhodamine B
Authors: Guo Huiqin , Fan Jing , Guo Yanhui 
Published: April 2007

AbstractA sensitive fluorimetric method is presented and discussed for the determination of pentachlorophenol in aqueous solutions. This method is based on the inhibitory effect of pentachlorophenol on the reaction of conventional Fenton [Fe(III) + H2O2] reagent with rhodamine B in the medium of perchloric acid, which results in the fluorescence quenching of rhodamine B. It was further found that the sensitivity for the determination was improved significantly when the molecular ligand EDTA was added. This improved system was therefore presented for the determination of pentachlorophenol. The characteristics of the excitation and emission spectra, optimization of the experimental conditions, the stability of the system and the influence of foreign matter have all been investigated. Under optimal conditions, the linear range for the determination of pentachlorophenol is 12–480 ng/mL with a 3σ limit of detection of 0.96 ng/mL. Compared with the conventional Fenton system, the improved system shows obvious advantages in both sensitivity and selectivity. By combination with the pretreatment of samples using ion exchange resins and XDA‐1 absorption resin, the improved Fenton method was used for the first time for the determination of pentachlorophenol in synthetic samples and natural water samples, and satisfactory results, in agreement with those of the HPLC method, were achieved. The possible mechanism of the reactions has also been discussed. Copyright © 2007 John Wiley & Sons, Ltd.
CT evaluation of the vidian canal localization
Authors: Yazar Fatih , Cankal Fatih , Haholu Aptullah , Kiliç Cenk , Tekdemir Ibrahim 
Published: April 2007

AbstractThe primary purpose of our work is to show that the vidian canal can be determined on CT imaging. The secondary goal is to establish the position and configuration of the vidian canal visualization. The CT imaging of vidian canals of 150 patients were examined in axial and coronal sections in 3 mm thickness made at 3 mm intervals. The varying course of the canal inside the bone, bone structure and diameter of the canal were investigated. In all cases, the canal was seen, and in 4 of the cases (1.3%) the canal was separated into two parts by a septum on its initial portion. In 36% of the cases it was embedded in the sphenoid corpus, partially protruded in 54% of the cases, and was connected to the bone with a stalk inside the sinus in 10% of the cases. The bony structure of the canal showed continuation in 68%, with 32% showing dehisans. The incidence of dehisans was 77% in the stalked cases and 45% in the protruded cases. It was determined that it is possible to evaluate the position and configuration of the vidian canal with CT imaging. This may be useful for diagnosing vidian nerve pathology and performing surgical intervention such as vidian neuroectomy and sinus surgery. Clin. Anat. 20:751–754, 2007. © 2007 Wiley‐Liss, Inc.
A Multiplexed Protein Kinase Assay
Authors: Shults Melissa D. , Kozlov Igor A. , Nelson Nicholas , Kermani Bahram G. , Melnyk Peter C. , Shevchenko Veronika , Srinivasan Anu , Musmacker Joseph , Hachmann John P. , Barker David L. , Lebl Michal , Zhao Chanfeng 
Published: April 2007

AbstractWe report a novel protein kinase assay designed for high‐throughput detection of one or many kinases in a complex mixture. A solution‐phase phosphorylation reaction is performed on 900 different peptide substrates, each covalently linked to an oligonucleotide tag. After incubation, phosphoserine, phosphothreonine, and phosphotyrosine are chemically labeled, and the substrates are hybridized to a microarray with oligonucleotides complementary to the tags to read out the phosphorylation state of each peptide. Because protein kinases act on more than one peptide sequence, each kinase can be characterized by a unique signature of phosphorylation activity on multiple substrates. Using this method, we determined signatures for 26 purified kinases and demonstrated that enzyme mixtures can be screened for activity and selectivity of inhibition.
Calix[4]arene‐Based Bis[2]catenanes: Synthesis and Chiral Resolution
Authors: Molokanova Olena , Bogdan Anca , Vysotsky Myroslav O. , Bolte Michael , Ikai Tomoyuki , Okamoto Yoshio , Böhmer Volker 
Published: April 2007

AbstractThe exclusive formation of hydrogen‐bonded dimers between tetraaryl and tetratosylurea calix[4]arenes has been used to prepare a series of ten “bisloop” tetraurea calix[4]arenes 3, in which adjacent phenylurea groups are covalently linked through α,ω‐dioxyalkane chains. This dimerization with tetratosylurea 2 as template preorganizes the alkenyl residues of tetra(m‐alkenyloxyphenyl) ureas 1 and enables their selective connection in high yield (up to 95 %) by olefin metathesis followed by hydrogenation. The “bisloop” calixarenes 3 also exclusively form heterodimers with 1. Thus, in a separated metathesis/hydrogenation sequence, a series of 14 cyclic bis[2]catenanes 4, in which two calix[4]arenes are connected through their wide rims by two pairs of interlocked rings (total size 29 to 41 atoms), were prepared in yields of up to 97 %. Optical resolution of these chiral bis[2]catenanes was studied by HPLC on chiral stationary phases. The single‐crystal X‐ray structure of one example (4(P,10)) confirmed the interlocking rings and revealed that the hydrogen‐bonded dimeric capsule of the calix[4]arene can be “completely” opened.
On the convergence and singularities of the J‐Flow with applications to the Mabuchi energy
Authors: Song Jian , Weinkove Benjamin 
Published: April 2007

AbstractThe J‐flow of S. K. Donaldson and X. X. Chen is a parabolic flow on Kähler manifolds with two Kähler metrics. It is the gradient flow of the J‐functional that appears in Chen's formula for the Mabuchi energy. We find a positivity condition in terms of the two metrics that is both necessary and sufficient for the convergence of the J‐flow to a critical metric. We use this result to show that on manifolds with ample canonical bundle, the Mabuchi energy is proper on all Kähler classes in an open neighborhood of the canonical class defined by a positivity condition. This improves previous results of Chen and of the second author. We discuss the implications of this for the problem of the existence of constant‐scalar‐curvature Kähler metrics.We also study the singularities of the J‐flow and, under certain conditions (which always hold for dimension 2) derive some estimates away from a subvariety. We discuss the conjectural remark of Donaldson that if the J‐flow does not converge on a Kähler surface, then it should blow up over some curves of negative self‐intersection. © 2007 Wiley Periodicals, Inc.
Blowup for nonlinear wave equations describing boson stars
Authors: Fröhlich Jürg , Lenzmann Enno 
Published: April 2007

AbstractWe consider the nonlinear wave equation

modeling the dynamics of (pseudorelativistic) boson stars. For spherically symmetric initial data, u0(x) ∈ C (ℝ3), with negative energy, we prove blowup of u(t, x) in the H1/2‐norm within a finite time. Physically this phenomenon describes the onset of “gravitational collapse” of a boson star. We also study blowup in external, spherically symmetric potentials, and we consider more general Hartree‐type nonlinearities. As an application, we exhibit instability of ground state solitary waves at rest if m = 0. © 2007 Wiley Periodicals, Inc.
Hamiltonian ODEs in the Wasserstein space of probability measures
Authors: Ambrosio Luigi , Gangbo Wilfrid 
Published: April 2007

AbstractIn this paper we consider a Hamiltonian H on 𝒫2(ℝ2d), the set of probability measures with finite quadratic moments on the phase space ℝ2d = ℝd × ℝd, which is a metric space when endowed with the Wasserstein distance W2. We study the initial value problem dμt/dt + ∇ · (𝕁dvtμt) = 0, where 𝕁d is the canonical symplectic matrix, μ0 is prescribed, and vt is a tangent vector to 𝒫2(ℝ2d) at μt, belonging to ∂H(μt), the subdifferential of H at μt. Two methods for constructing solutions of the evolutive system are provided. The first one concerns only the case where μ0 is absolutely continuous. It ensures that μt remains absolutely continuous and vt = ∇H(μt) is the element of minimal norm in ∂H(μt). The second method handles any initial measure μ0. If we further assume that H is λ‐convex, proper, and lower‐semicontinuous on 𝒫2(ℝ2d), we prove that the Hamiltonian is preserved along any solution of our evolutive system, H(μt) = H(μ0). © 2007 Wiley Periodicals, Inc.
Loop Spaces and the hypoelliptic Laplacian
Authors: Bismut Jean‐Michel 
Published: April 2007

AbstractThe purpose of this paper is to introduce some ideas that motivated the construction of the hypoelliptic Laplacian as a deformation of Hodge theory, which interpolates between Hodge theory and the geodesic flow. Results obtained with Lebeau on the analysis of the hypoelliptic Laplacian are also presented. © 2007 Wiley Periodicals, Inc.
A Comparative Study on the Photochemistry of Two Bipyridyl Derivatives: [2,2′‐Bipyridyl]‐3,3′‐diamine and [2,2′‐Bipyridyl]‐3,3′‐diol
Authors: Ortiz‐Sánchez Juan Manuel , Gelabert Ricard , Moreno Miquel , Lluch José M. 
Published: April 2007

AbstractThe two isoelectronic bipyridyl derivatives, [2,2′‐bipyridyl]‐3,3′‐diamine and [2,2′‐bipyridyl]‐3,3′‐diol, are experimentally known to undergo very different excited‐state double‐proton‐transfer processes, which result in fluorescence quantum yields that differ by four orders of magnitude. Herein, density functional theory (DFT), time‐dependent DFT (TDDFT), and complete active space self‐consistent field (CASSCF) calculations are used to study the double‐proton‐transfer processes in the ground and first singlet π→π* excited state. The quantum‐chemistry calculations indicate 1) the existence of only one energy minimum in the ground electronic state corresponding to reactants (thus avoiding the possibility of a fast fluorescent relaxation process from the photoproducts region), 2) an endoergic process of the complete double proton transfer, and 3) the presence of a conical intersection in the excited intermediate region of [2,2′‐bipyridyl]‐3,3′‐diamine. These facts explain the very low fluorescence quantum yield in [2,2′‐bipyridyl]‐3,3′‐diamine compared to [2,2′‐bipyridyl]‐3,3′‐diol.
Inter‐organizational use of EMSs in supply chain management: some experiences from Poland and Sweden
Authors: Nawrocka Dagmara 
Published: April 2007

AbstractThe paper investigates the possibility of using environmental management systems (EMSs) as a tool for the environmental management of supply chains. Based on interviews with environmental managers of selected companies, the paper highlights the importance of taking a long‐term perspective in terms of both the cooperation with suppliers and developing the supply chain perspective for EMSs. The role of cultural influence from foreign partner companies in building the proactive environmental focus and stimulating the spread of EMSs is underlined here. In addition, the paper looks at the development, use and control of supply chain environmental requirements and their possible integration into the buyer's and supplier's EMSs. Finally, important shortcomings of EMSs, such as the lack of enforcement forbearance and the credibility of ISO 14001 certification, are discussed. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
Sinistral equal‐size spiral cleavage of the indirectly developing polychaete Hydroides elegans
Authors: Arenas‐Mena Cesar 
Published: April 2007

AbstractTwo major variants of the stereotypic spiral cleavage correlate with distinct developmental modes in polychaetes. Indirect development through a feeding trochophore larva correlates with development from four equal‐sized blastomeres, whereas direct development correlates with unequal cleavage characterized by a large dorsal blastomere precursor maternally predetermined. The equal‐size spiral cleavage of the indirectly developing serpulid Hydroides elegans has been reconstructed from serial sections of nuclei‐stained embryos. The order of cell divisions has been determined from the 2‐cell stage to the 80‐cell stage, when gastrulation cell movements start to overlap with late spiral‐cleavage divisions. In contrast to related species, the third cleavage in Hydroides elegans is invariably sinistral. The four quadrants remain indistinct until the 60‐cell stage, when the small 2d22 and large 2d21 cells are generated. The developmental significance of the invariant spiral cleavage relates to the spatial distribution of gene functions that it partitions and their relation to blastomere fate commitments. The conservation and divergence of the cleavage pattern among spiralians is well suited to study the developmental control of the cell‐cleavage machinery and its evolution. Developmental Dynamics 236:1611–1622, 2007. © 2007 Wiley‐Liss, Inc.
Electronic Structure of Linearly Coordinated EQ Complexes of the Type [(N3N)W(EQ)] [N3N = N(CH2CH2NSiMe3)3; E = P, As, Sb, Bi; Q = O, S, Se, Te]: A DFT Study
Authors: Balázs Gábor , Green Jennifer C. , Mingos D. Michael P. 
Published: April 2007

AbstractDensity functional theory (DFT) calculations were carried out on the terminal EQ complexes [(N3N)W(EQ)] {N3N = N(CH2CH2NSiMe3)3; E = P, As, Sb, Bi; Q = O, S, Se Te} to clarify the bonding situation within the linear Nax–W–E–Q core. This unusual structural motif gives rise to a bonding arrangement in which the π‐electron density is delocalised over the three atoms of the W–E–Q unit. Fragment calculations and natural bond order (NBO) data indicated that the σ‐bonding component of the Nax–W–E–Q unit comprises two occupied σ orbitals, while the π component of bonding comprises two sets of degenerate π orbitals. In general, the π orbitals of the Nax–W–E–Q core are higher in energy compared to the σ orbitals. The phosphorus monoxide (EQ = PO) complexes provide an exception to this rule, with the 1π orbitals of the W–P–O core lower in energy than the σ orbitals. Generally, as the atomic number of either the pnicogen (E) or chalcogen (Q) atom increases the extent of σ‐orbital delocalisation decreases, whereas the π‐orbital delocalisation increases. Fractional bond orders and Wiberg bond indices were used to establish whether localisation of the π‐electron density gives rise to a W–E or an E–Q double or triple bond. Both methods indicate a W–E as well as an E–Q double bond. The ionic nature of the complexes were analysed by inspection of the Hirschfeld charge distribution which shows only a moderate ionic character. Exceptions are the pnicogen monoxide complexes, which are more ionic. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Dendritic Host Molecules with a Polycationic Core and an Outer Shell of Dodecyl Groups
Authors: van de Coevering Rob , Bruijnincx Pieter C. A. , van Walree Cornelis A. , Klein Gebbink Robertus J. M. , van Koten Gerard 
Published: April 2007

AbstractThe synthesis of a topologically new type of dendrimer is presented in which a permanently positively charged core is decorated with a shell that is apolar and aliphatic in nature. The novel polyionic dendrimers were successfully applied as hosts for a predefined number of anionic guests, as is shown for the dye methyl orange. The aliphatic periphery of the dendrimers efficiently shields the ion pairs and renders the dendrimers fully soluble in organic solvents that are as apolar as hexane and, furthermore, provides them with an interesting phase behavior that appears not to be sensitive to the type of anion associated with it.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis of Enantiopure 1‐Azaspiro[4.5]decanes by Iodoaminocyclization of Allylaminocyclohexanes
Authors: Diaba Faïza , Puigbó Gemma , Bonjoch Josep 
Published: April 2007

AbstractThe 5‐endo iodine‐promoted ring closure of 4‐allyl‐4‐(alkylamino)cyclohexanone derivatives gives the corresponding 1‐azaspiro[4.5]decanes in good yields. The reaction was tested with enantiopure homoallylamines to evaluate the diastereoselectivity of the process and to provide a route for possible intermediates to the natural products embodying this azabicyclic ring.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Die Kultur, der Kommerz und das Image
Authors: Kaschuba Wolfgang , Färber Alexa , Gdaniec Cordula 
Published: April 2007

AbstractTheater und Kunst, Musikszenen oder Subkulturen sind zu einem „harten”︁ Standortfaktor für Metropolen geworden. Kulturwissenschaftler untersuchen am Beispiel von Berlin und Moskau, wie aus Kultur Kapital gemacht wird
No excess risk for colorectal cancer among subjects seropositive for the JC polyomavirus
Authors: Lundstig Annika , Stattin Pär , Persson Kenneth , Sasnauskas Kestutis , Viscidi Raphael P. , Gislefoss Randi Elin , Dillner Joakim 
Published: April 2007

AbstractThe human polyomaviruses JC virus (JCV) and BK virus (BKV) are oncogenic in experimental systems and commonly infect humans. JCV DNA has been reported to be present in human colon mucosa and in colorectal cancers. To investigate whether the risk for colorectal cancer is associated with JCV or BKV infection, we performed a case–control study nested in the Janus biobank, a cohort of 330,000 healthy Norwegian subjects. A 30‐year prospective follow‐up using registry linkages identified 386 men with colorectal cancer who had baseline serum samples taken >3 months before diagnosis. Control subjects were matched for sex, age and date of blood sampling and county of residence. Seropositivity for JCV or BKV had high (97–100%) sensitivity for detection of viral DNA‐positive subjects and discriminated the different polyomaviruses. Seropositivity was mostly stable over time in serial samples. The relative risk for colorectal cancer among JCV seropositive subjects was 0.9 (95% CI: 0.7–1.3) and the BKV‐associated relative risk was 1.1 (95% CI: 0.8–1.5). Determining seropositivity using alternative cutoffs also found no evidence of excess risk. In summary, this prospective study found no association between JCV or BKV infections and excess risk for colorectal cancer. © 2007 Wiley‐Liss, Inc.