bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Light‐Emitting Mixed‐Ligand Iridium(III) Complex with a Terpyridine‐Poly(ethylene glycol) Macroligand
Authors: Holder Elisabeth , Marin Veronica , Meier Michael A. R. , Schubert Ulrich S.
Published: August 2004

Summary: A monoterpyridine‐poly(ethylene glycol) (mono‐tpy‐PEG) and a novel monoterpyridine‐PEG‐functionalized iridium(III) complex were successfully synthesized and fully characterized by means of NMR, IR, and UV‐vis spectroscopy, as well as gel permeation chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The functionalized monoterpyridine iridium(III) complex was synthesized by a bridge‐splitting reaction of a dimeric iridium(III) precursor complex using a chelating terpyridine ligand with a poly(ethylene glycol) tail. With this approach, a new class of light‐emitting polymeric materials revealing interesting optical properties was made avaialable.

Upon excitation of a spin‐coated film of the iridium(III) complex prepared here, a yellow emission color (two bands in figure) was observed.

image

Upon excitation of a spin‐coated film of the iridium(III) complex prepared here, a yellow emission color (two bands in figure) was observed.
A low‐loss wideband suspended coaxial transmission line
Authors: Llamas‐Garro I. , Lancaster M. J. , Hall P. S.
Published: August 2004

This paper presents a transmission‐line structure suitable for micromachining technology. The structure is an air‐filled square coaxial cable, which is very low loss and has been designed in order to utilise current manufacturing processes. This transmission line demonstrates that such a structure can be designed to cover very wide bandwidth. As the cable is air filled, the centre conductor needs to be supported and this is accomplished by attaching quarter‐wavelength stubs to the ground. The design method of such a cable is presented in detail and the results of an X‐band component are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 93–95, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20386
Dual‐frequency‐selective surfaces for near‐infrared bandpass filters
Authors: Govindaswamy S. , East J. , Terry F. , Topsakal E. , Volakis J. L. , Haddad G. I.
Published: August 2004

A bandpass filter resonating at ∼1.4 μm and based on a dual‐frequency‐selective surface design is fabricated and characterized on a silicon substrate. The filter consists of square apertures arranged in a square lattice and separated by magnesium‐fluoride dielectric layers. Simulations indicate minimal change in spectral reflectance versus overlay misalignment. The measured reflectance shows almost zero minima and a sharp roll‐off. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 95–98, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20387
Hybrid absorbing boundary conditions based on fast nonuniform grid integration for nonconvex scatterers
Authors: Boag Amir , Shemer Uri , Kastner Raphael
Published: August 2004

Novel hybrid (local–global) absorbing boundary conditions (ABCs) are proposed for the truncation of computational domains in finite‐method analysis of open‐region problems. The pertinent boundary integration is accelerated by the nonuniform grid‐interpolation scheme, resulting in a fast algorithm for treating electrically large objects with largely concave outer boundaries. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 102–106, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20389
Antenna‐beam shaping from offset defects in UC‐EBG cavities
Authors: Hao Y. , Alomainy A. H. , Parini C. G.
Published: August 2004

We present a new application of uniplanar compact electromagnetic bandgap (UC‐EBG) structures in antenna‐beam shaping for indoor mobile communications. Such UC‐EBGs are used to construct Fabry–Perot‐type cavities in which the enhanced directivity can be achieved from conventional patch antennas. This paper demonstrates that an antenna beam can be shaped by shifting the defects (patch antennas) from the centre of UC‐PBG cavities. The theoretical predictions are verified by numerical simulations and measurement results, and it appears that antenna‐beam shaping in UC‐EBG cavities can achieve the same radiation patterns as complex planar‐antenna arrays used for improving the quality and strength of sent/received signals in mobile base stations. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 108–112, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20391
A switched‐beam antenna of monopoles housed in a radial guide with transition to free space
Authors: Janapsatya Januar , Bialkowski Marek E.
Published: August 2004

The design of a switched‐beam antenna formed by a circular array of monopoles housed inside a radial guide with a transition to free space is presented. Two alternative types of transitions to free space, one using a truncated conducting cone and the other created by a tapered dielectric material at the edge of the radial guide, are described. The use of the radial guide with transition increases the return‐loss bandwidth of the array and enables shaping its beam in elevation. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 115–118, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20393
Wideband microstrip‐fed printed bow‐tie antenna for phased‐array systems
Authors: Eldek Abdelnasser A. , Elsherbeni Atef Z. , Smith Charles E.
Published: August 2004

A microstrip‐fed printed bow‐tie antenna is presented in order to achieve wide bandwidth, high gain, and size reduction. A comparison between the bow‐tie and the quasi‐Yagi (dipole and director) antennas shows that the bow‐tie antenna has a wider bandwidth, higher gain, lower front‐to‐back ratio, lower cross‐polarization level, and smaller size. Two‐element arrays are designed and their characteristics are compared. The bow‐tie antenna yields lower coupling for the same distance between elements. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 123–126, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20396
Unsplit‐field perfectly matched layer for higher‐order alternating direction implicit finite‐difference time‐domain method
Authors: Leung Y. F. , Chan C. H.
Published: August 2004

An unsplit‐field perfectly matched layer (UPML) medium is introduced for higher‐order alternating direction implicit (ADI) formulation of the FDTD Method. By applying the proposed formulation, no field splitting is required for implementing higher‐order ADI‐FDTD PML; thus, the unconditionally stable nature of ADI‐FDTD is remained. The results of 2D simulation are used to illustrate the effectiveness of the PML medium, which is constructed using the proposed approach as an absorber for numerical grid truncation. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 130–133, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20398
A Zn‐diffused Mach–Zehnder modulator on lithium niobate at 1.55‐μm wavelength
Authors: Twu Ruey‐Ching , Chang Ching‐Yu , Wang Way‐Seen
Published: August 2004

Zn‐diffused Mach–Zehnder intensity modulators operating at 1.55‐μm wavelength are demonstrated on a z‐cut and a y‐cut LiNbO3 substrate for the first time. The switching voltages are measured and the corresponding values of switching voltage‐length product are 9.6 V‐cm and 13.5 V‐cm for the z‐cut and y‐cut modulators, respectively. Both the modulated extinction ratios are about 20 dB. The results show that the Zn‐diffused modulators not only have electro‐optic tunability as great as that of the Ti‐diffused ones, but also have more flexibility for device fabrication. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 142–144, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20401
Global modeling of a periodic coplanar waveguide structure for filter applications using an efficient iterative procedure
Authors: Sboui N. , Gharsallah A. , Gharbi A. , Baudrand H.
Published: August 2004

A global modelizing of periodic structures for coplanar waveguide filter is presented. These structures offer a very low insertion loss; thus, they can be exploited to achieve a high performance in miniature microwave filters. The analysis is achieved by using a new iterative method based on the wave concept. In this method, a recursive relationship between a given source and reflected waves from the circuit plane is generated. The good agreement between simulated and experimental published data justifies the design procedure. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 157–160, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20406
Effect of a nipi delta‐doping superlattice on In1−xGaxAs/In1−yAlyAs amplitude modulator parameters
Authors: Tribuzy C. V.‐B. , Pires M. P. , Souza P. L.
Published: August 2004

A theoretical study of the performance of amplitude modulators using a nipi delta‐doping superlattice in InGaAs/InAlAs multiple quantum‐well (QW) structures is presented. The structure is such that an n‐type delta‐doping layer is placed at the center of the InGaAs QWs and a p‐type is placed at the center of the InAlAs barriers. From the calculated absorption curves, modulator parameters such as CR, IL, and chirp are estimated and a comparison of the performance of an InGaAs/InAlAs modulator with and without the nipi delta‐doping superlattice is carried out. The study shows that an amplitude modulator containing a nipi delta‐doping superlattice in the InGaAs/InAlAs multiple QW structure presents an improved performance, compared to that without the doping superlattice, as long as the QW composition is adequately chosen. It is shown that for such structures, contrary to the undoped counterpart, it is, in principle, possible to achieve polarization insensitivity and appropriate chirp parameters simultaneously. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 168–173, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20410
Analysis of waveguide discontinuities using a hybrid method combining the Helmholtz weak form and mode expansion
Authors: Wu H. C. , Dou W. B.
Published: August 2004

A new approach for the analysis of waveguide multiports discontinuities is presented in this paper. This approach is a combined method of the mode‐expansion method and finite‐element method, which is based on the weak form of the Helmholtz equation. We use a mode expansion technique other than PML to truncate the computing space of finite element. Multiport structures such as H‐Plane forked T‐junction, waveguide loaded with two dielectric posts, and E‐plane filter are studied as examples. The calculated results of these structures are shown and compared, respectively, to those in references. Good agreement between them is observed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 173–177, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20411
57Fe NMR spectroscopy of ferrocenes bearing π‐acceptor substituents
Authors: Wrackmeyer Bernd , Tok Oleg L. , Ayazi Anahid , Maisel Heidi E. , Herberhold Max
Published: August 2004

Ferrocene derivatives bearing π‐acceptor substituents in 1‐ or 1,1′‐positions such as carbonyl group(s) (1, 2), a sulfinyl group (4) or boryl group(s) (5, 6, 9) and related [3]ferrocenophanes (3, 7, 10, 12, 13) and a [4]ferrocenophane (8) were studied by 57Fe NMR spectroscopy. The deshielding effect of the respective π‐acceptor substituent can be partially or fully compensated by distortion of the ferrocene geometry. Both aspects become apparent by comparing δ57Fe data of the [n]ferrocenophanes with those of related non‐cyclic derivatives. Copyright © 2004 John Wiley & Sons, Ltd.
Triphenylphosphane complex formation with hexyn‐1‐yl silver
Authors: Létinois‐Halbes Ulla , Pale Patrick , Berger Stefan
Published: August 2004

Hexyn‐1‐yl silver shows broad signals in 1H, 13C and 109Ag NMR. In the presence of 1 equiv. of triphenylphosphane, the signals are much sharper and at low temperature 109Ag,31P and 107Ag,31P coupling can be observed. On 109Ag decoupling, the 31P spectrum still shows the 107Ag,31P coupling indicating the formation of a coordination complex. Copyright © 2004 John Wiley & Sons, Ltd.
Density functional computation of 49Ti NMR chemical shifts
Authors: Bühl Michael , Mauschick Frank T.
Published: August 2004

49Ti chemical shifts of TiX4 (X = Cl, Br, F), TiClnMe(4−n) (n = 0–3), Ti(C5H5)2X2 (X = F, Cl, Br) and Ti(CO)62− were computed, using geometries optimized with the gradient‐corrected BP86 density functional, at the GIAO (gauge‐including atomic orbitals)–Hartree–Fock, BPW91, and B3LYP levels. For this set of compounds, substituent effects on δ(49Ti) are reasonably well described with all methods considered; judged from mean absolute deviations from experiment, B3LYP performs best. Zero‐point corrections to the δ(49Ti) values, evaluated from a perturbational approach based on vibrationally averaged effective geometries, turn out to be fairly small. Electric field gradients computed with the B3LYP functional do not correlate with trends in 49Ti NMR linewidths. Attempts are reported to correlate the δ(49Ti) values of Ti[YC(O)CHC(O)Y]2Cl2 (Y = H, Me, CF3, CN, F, Cl and Br) with the rate‐limiting propagation barrier for ethylene polymerization using catalysts derived from these precursors. Copyright © 2004 John Wiley & Sons, Ltd.
PGSE diffusion, 1H–19F HOESY and NMR studies on several [Rh(1,5‐COD)(Biphemp)]X complexes: detecting positional anion effects
Authors: Anil Kumar P. G. , Pregosin Paul S. , Schmid Thomas M. , Consiglio Giambattista
Published: August 2004

Three new salts of Rh(I), [Rh(1,5‐COD)(Biphemp)]X, Biphemp = (6,6′‐dimethylbiphenyl‐2,2′‐diyl)bis(diphenylphosphine), X = BF4−, 2a, PF6−, 2b, and CF3SO3−, 2c, were prepared and studied using PGSE diffusion, 1H–19F HOESY and inverse 103Rh (amongst other) NMR methods. Although the immediate coordination sphere of the cation does not sense the change in the anion, the PGSE diffusion and 1H–19F HOESY data suggest that, in addition to some ion pairing, each of the anions in 2 demonstrates selectivity in its approach towards the cation. Copyright © 2004 John Wiley & Sons, Ltd.
Multinuclear NMR study of some organoplatinum complexes containing multifunctional azines as chelating ligands
Authors: Gudat Dietrich , Dogan Akbey , Kaim Wolfgang , Klein Axel
Published: August 2004

1H‐detected indirect NMR techniques were used to determine 15N and 195Pt NMR parameters for a series of organoplatinum(IV) complexes and one platinum(II) complex containing nitrogen‐based azobispyridine, bispyridyltetrazine, and bipyrimidine ligands. The inverse technique permitted the detection of small 4J(Pt,H) and 5J(Pt,H) long‐range couplings and the acquisition of 15N NMR data in natural isotopic abundance via nJ(N,H) intra‐ and inter‐ligand couplings, but failed in cases where coherence transfer is quenched by rapid relaxation of the metal atom. In one case, analysis of satellite patterns in a set of 1H,15N, 1H,195Pt and 1H,13C correlation spectra allowed a positive sign to be determined for 1J(Pt,15N). Qualitative arguments are presented to explain the observed 15N coordination shifts in complexes with different azine ligands in terms of azine–M dative bond formation and LnM–azine back‐donation. Copyright © 2004 John Wiley & Sons, Ltd.
A vanadium‐51 NMR study of the binding of vanadate and peroxovanadate to proteins
Authors: Rehder Dieter , Časný Marian , Grosse Reiner
Published: August 2004

51V quadrupolar central transition NMR spectra of buffered (pH 7.6–8.0) solutions of bovine apo‐transferrin (Tf) and bovine prostatic acid phosphatase (Pp) treated with vanadate show normal features (chemical shifts between −515 and −542 ppm) corresponding to the complexation of VO2+ to the Tf binding site and the Pp active centre, respectively. Addition of H2O2 leads to the temporary formation of complexed VO(O2)+(δ ≈ −595). Vanadate‐dependent bromoperoxidase from the alga Ascophyllum nodosum exhibits an unusually high shielding both for the native (δ = −931) and the peroxo form (δ = −1135) of the enzyme. A resonance at −471 ppm is traced back to an inactive form with oxovanadium(V) in a trigonal‐bipyramidal array. Copyright © 2004 John Wiley & Sons, Ltd.
Solid‐state 109Ag CP/MAS NMR spectroscopy of some diammine silver(I) complexes
Authors: Bowmaker Graham A. , Harris Robin K. , Assadollahzadeh Behnam , Apperley David C. , Hodgkinson Paul , Amornsakchai Pornsawan
Published: August 2004

Solid‐state cross‐polarization magic‐angle spinning (CP/MAS) NMR spectra were recorded for the compounds [Ag(NH3)2]2SO4, [Ag(NH3)2]2SeO4 and [Ag(NH3)2]NO3, all of which contain the linear or nearly linear two‐coordinate [Ag(NH3)2]+ ion. The 109Ag CP/MAS NMR spectra show centrebands and associated spinning sideband manifolds typical for systems with moderately large shielding anisotropy, and splittings due to indirect 1J(109Ag,14N) spin–spin coupling. Spinning sideband analysis was used to determine the 109Ag shielding anisotropy and asymmetry parameters Δσ and η from these spectra, yielding anisotropies in the range 1500–1600 ppm and asymmetry parameters in the range 0–0.3. Spectra were also recorded for 15N and (for the selenate) 77Se. In all cases the number of resonances observed is as expected for the crystallographic asymmetric units. The crystal structure of the selenate is reported for the first time. One‐bond (107, 109Ag,15N) coupling constants are found to have magnitudes in the range 60–65 Hz. Density functional calculations of the Ag shielding tensor for model systems yield results that are in good agreement with the experimentally determined shielding parameters, and suggest that in the solid compounds Δσ and η are reduced and increased, respectively, from the values calculated for the free [Ag(NH3)2]+ ion (1920 ppm and 0, respectively), primarily as a result of cation–cation interactions, for which there is evidence from the presence of metal‐over‐metal stacks of [Ag(NH3)2]+ ions in the solid‐state structures of these compounds. Copyright © 2004 John Wiley & Sons, Ltd.
Application of HMQC spectroscopy to the observation of the metal resonance in polymetallic compounds: the effect of multiple‐metal spin transitions
Authors: Heaton B. T. , Iggo J. A. , Podkorytov I. S. , Tunik S. P.
Published: August 2004

Multiple‐metal spin transitions which distort the HMQC spectra of rhodium carbonyl clusters are discussed. These effects are seen whenever the detector nucleus, e.g. 13C or 31P, couples to more than one metal spin and are not restricted to detector ligands occupying edge‐ or face‐bridging sites. These effects are illustrated in, but not limited to, the 13C‐{103Rh} and 31P‐{103Rh} HMQC spectra of [Rh6(CO)15L], (where L = P(4‐F‐C6H4)3), [Rh4(CO)11{P(OPh)3}], [Rh6C(CO)15]2 − and [Rh2(carboxylate)2PPh3]. The effect is to modulate the intensity and position of the correlations in the metal dimension; cross peaks are displaced from the true chemical shift, additional cross peaks are seen and the intensity of the coherences varies as a function of the preparation delay, d2, and coupling constant, and may go to zero at the conventional value of 1/(2J). Analyses of the relevant spin systems are given together with experimental strategies to overcome these effects. Copyright © 2004 John Wiley & Sons, Ltd.
Indirect nuclear 57Fe13C and 57Fe1H spin–spin coupling in ferrocenes and cyclopentadienyliron complexes: measurements and DFT calculations
Authors: Wrackmeyer Bernd , Tok Oleg L. , Koridze Avthandil A.
Published: August 2004

Several 57Fe‐labeled ferrocene derivatives and other cyclopentadienyliron complexes were studied by 57Fe and 13C NMR with respect to isotope‐induced chemical shifts 1Δ12/13C(57Fe) and the magnitude and sign of coupling constants 1J(57Fe,13C) and 2J(57Fe,1H). The geometries of the complexes were optimized by DFT methods [B3LYP/6–311+G(d,p)] and chemical shifts (GIAO) and coupling constants were calculated at the same level of theory. The trends in calculated 57Fe nuclear shielding agree well with the experimental data and, in the case of coupling constants 1J(57Fe,13C) and 2J(57Fe,1H), both sign and magnitude are correctly reproduced. Copyright © 2004 John Wiley & Sons, Ltd.
Indirect coupling to quadrupolar nuclei: observation of 1J(105Pd,31P) in one‐ and two‐dimensional 31P CP/MAS spectra
Authors: Rüegger Heinz
Published: August 2004

High‐resolution solid‐state 31P cross‐polarization magic angle spinning (CP/MAS) spectra of a series of Pd(II) complexes were obtained. All of these spectra exhibit low‐intensity satellite peaks flanking the main resonances which are assigned to originate from a combination of direct (D) and indirect (J) spin–spin coupling between the 31P and the 105Pd spins. The parameter 1J(105Pd,31P) is found to be sensitive to the nature of the ligand in a trans position and thus of great value in assigning the configuration, i.e. cis or trans, in square‐planar complexes of Pd(II). A linear relationship between 1J(105Pd,31P) and 1J(195Pt,31P) in analogous Pd(II) and Pt(II) complexes is suggested, the latter parameter being a factor of ca 14 larger. Two‐dimensional exchange spectroscopy proved valuable in resolving overlapping resonances and relating pairs of inequivalent 31P spins within the same complex and spreading their satellite manifolds into two dimensions. These two spectral features are unrelated, being due to dipolar coupling among the phosphorus spins in the former and finite lifetimes of the spin states of the 105Pd isotope in the latter case. Copyright © 2004 John Wiley & Sons, Ltd.
Rhodium‐103 NMR of [Rh(X)(PPh3)3] [X = Cl, N3, NCO, NCS, N(CN)2, NCBPh3, CNBPh3, CN] and derivatives containing CO, isocyanide, pyridine, H2 and O2. Ligand, solvent and temperature effects
Authors: Carlton Laurence
Published: August 2004

Rhodium‐103 chemical shifts are reported for 62 compounds, namely [Rh(X)(PPh3)3] [X = Cl, N3, NCO, NCS, N(CN)2, NCBPh3, CNBPh3, CN] and derivatives formed by replacement of a phosphine by CO, xylyl isocyanide (XNC) and pyridine and/or by oxidative addition of H2 or O2 to give trans‐[Rh(X)(PPh3)2(CO)] (δ in the range −816 to −368 ppm) trans‐[Rh(X)(PPh3)2(XNC)] (δ −817 to −250 ppm), cis‐[Rh(X)(PPh3)2(py)] (the trans isomer is formed with X = CN, CNBPh3) (δ −233 to 170 ppm), [Rh(X)(H)2(PPh3)3] (δ −611 to 119), trans‐[Rh(X)(H)2(PPh3)2(py)] (δ −30 to 566 ppm), [Rh(X)(O2)(PPh3)3] (δ 1393 to 3273 ppm) and cis‐[Rh(X)(O2)(PPh3)2(py)] (δ 1949 to 3374 ppm). For the majority of these compounds data were obtained from solutions in chloroform and in toluene at temperatures of 247 and 300 K; for [Rh(X)(PPh3)3] (δ −562 to −4 ppm) data are reported at a number of temperatures in the range 195–300 K for solutions in chloroform, toluene and dichloromethane and at 300 K for solutions in DMSO. The expected trend to lower δ(103Rh) with decreasing temperature (vibrational shielding) is observed for the dichloromethane data, but data from solutions {of [Rh(X)(PPh3)3]} in chloroform and toluene show a number of features which diverge from this pattern, i.e. shifts to higher δ are found to accompany a decrease in temperature, most noticeably where X = CN and Cl [on changing the solvent from dichloromethane to chloroform changes in δ(103Rh) of up to 172 ppm are observed]. These results are interpreted in terms of a hydrogen‐bonded interaction with the solvent that is enhanced by the presence of a polarizable ligand (CN, Cl). With a ligand (O2CCF3) that is only weakly polarizable the solvent dependence of δ(103Rh) is minimal. Copyright © 2004 John Wiley & Sons, Ltd.
Richness of isomerism in labile octahedral Werner‐type cobalt(II) complexes demonstrated by 19F NMR spectroscopy: structure and stability
Authors: Novitchi Ghenadie , Riblet Fabrice , Helm Lothar , Scopelliti Rosario , Gulea Aurélian , Merbach André E.
Published: August 2004

The cobalt(II) complexes [CoL2(R2‐Py)2] (1–4) where HLA = 1,1,1‐trifluoro‐5,5‐dimethyl‐2,4‐hexanedione, R2‐Py = 4‐methylpyridine (1), HLB = 4,4,4‐trifluoro‐1‐(2‐thienyl)‐1,3‐butanedione, R2‐Py = 4‐methylpyridine (2), 4‐phenylpyridine (3) and S‐(−)‐1‐(4‐pyridyl)ethanol (4) were prepared by two‐step reactions. X‐ray structure analysis of [CoLA2(CH3‐Py)2] revealed the {trans(N)‐trans(CF3)‐trans} configuration for the complex obtained by crystallization from ethanol. A dynamic equilibrium between the five possible stereoisomers was observed for each complex 1–4 in solution by 19F NMR spectroscopy. The criteria used for full NMR assignment (180–265 K) include comparison of integral ratios, cis(N) and trans(N) differentiation in presence of the chiral amine [S‐(−)‐1‐(4‐pyridyl)ethanol], effect of solvent polarity on the relative stabilities of the five isomers and observation of trans influences in a mixture of complexes. Thermodynamic parameters for the equilibria between the isomers of 2 in CD2Cl2 (ΔHi,j, ΔSi,j and Ki,j) were obtained from signal integrals. The two trans(N) isomers are slightly more stable than the three cis(N) isomers at low temperature [ΔG°i,j (max) = 2.8 kJ mol−1 at 179.8 K], but this stability difference almost vanishes with increasing temperature [ΔG°i,j (max) = 1.0 kJ mol−1 at 265.0 K]. The values found for ΔH°i,j are relatively small and largely entropy compensated. Copyright © 2004 John Wiley & Sons, Ltd.
103Rh NMR spectroscopy and its application to rhodium chemistry
Authors: Ernsting Jan Meine , Gaemers Sander , Elsevier Cornelis J.
Published: August 2004

Rhodium is used for a number of large processes that rely on homogeneous rhodium‐catalyzed reactions, for instance rhodium‐catalyzed hydroformylation of alkenes, carbonylation of methanol to acetic acid and hydrodesulfurization of thiophene derivatives (in crude oil). Many laboratory applications in organometallic chemistry and catalysis involve organorhodium chemistry and a wealth of rhodium coordination compounds is known. For these and other areas, 103Rh NMR spectroscopy appears to be a very useful analytical tool. In this review, most of the literature concerning 103Rh NMR spectroscopy published from 1989 up to and including 2003 has been covered. After an introduction to several experimental methods for the detection of the insensitive 103Rh nucleus, a discussion of factors affecting the transition metal chemical shift is given. Computational aspects and calculations of chemical shifts are also briefly addressed. Next, the application of 103Rh NMR in coordination and organometallic chemistry is elaborated in more detail by highlighting recent developments in measurement and interpretation of 103Rh NMR data, in relation to rhodium‐assisted reactions and homogeneous catalysis. The dependence of the 103Rh chemical shift on the ligands at rhodium in the first coordination sphere, on the complex geometry, oxidation state, temperature, solvent and concentration is treated. Several classes of compounds and special cases such as chiral rhodium compounds are reviewed. Finally, a section on scalar coupling to rhodium is provided. Copyright © 2004 John Wiley & Sons, Ltd.
NMR spectroscopy of organolithium compounds. XXVI—The aggregation behaviour of methyllithium in the presence of LiBr and LiI in diethyl ether and tetrahydrofuran
Authors: Fox Thomas , Hausmann Heike , Günther Harald
Published: August 2004

1H, 6Li and 13C NMR spectroscopy were used to determine the structure of aggregates formed in mixtures of methyllithium, H3CLi, and lithium bromide and iodide in diethyl ether and tetrahydrofuran. From the chemical shifts, the signal intensity distribution and the isotope shifts observed for partially deuterated systems, it was shown that generally tetrameric structures with different halogen contents dominate. For methyllithium–lithium bromide (1:1) in THF a considerable concentration of an H3CLiLiBr dimer was found. For the first time, deuterium‐induced 6Li isotope shifts over four bonds were observed. Copyright © 2004 John Wiley & Sons, Ltd.
Compaction process in sedimentary basins: the role of stiffness increase and hardening induced by large plastic strains
Authors: Deudé V. , Dormieux L. , Maghous S. , Barthélémy J. F. , Bernaud D.
Published: August 2004

This paper is devoted to the simulation of large strain compaction process in sedimentary basins. Special attention is paid to the effects of large porosity changes on the elastic and plastic mechanical properties of the sediment material. The latter are introduced in the constitutive behaviour in the framework of a micromechanical reasoning. In particular, the proposed approach avoids the problem of negative porosities that are predicted by classical models under high confining pressures.

Some closed‐form solutions are presented in the simplified case of one‐dimensional compaction. While the influence of stiffness increase is shown to be negligible as regards the compaction law, it proves to affect significantly the stress and porosity profiles. Copyright © 2004 John Wiley & Sons, Ltd.
Three dimensional simulation of fluid flow in X‐ray CT images of porous media
Authors: Al‐Omari A. , Masad E.
Published: August 2004

A numerical scheme is developed in order to simulate fluid flow in three dimensional (3‐D) microstructures. The governing equations for steady incompressible flow are solved using the semi‐implicit method for pressure‐linked equations (SIMPLE) finite difference scheme within a non‐staggered grid system that represents the 3‐D microstructure. This system allows solving the governing equations using only one computational cell. The numerical scheme is verified through simulating fluid flow in idealized 3‐D microstructures with known closed form solutions for permeability. The numerical factors affecting the solution in terms of convergence and accuracy are also discussed. These factors include the resolution of the analysed microstructure and the truncation criterion. Fluid flow in 2‐D X‐ray computed tomography (CT) images of real porous media microstructure is also simulated using this numerical model. These real microstructures include field cores of asphalt mixes, laboratory linear kneading compactor (LKC) specimens, and laboratory Superpave gyratory compactor (SGC) specimens. The numerical results for the permeability of the real microstructures are compared with the results from closed form solutions. Copyright © 2004 John Wiley & Sons, Ltd.
Specific functions of Drosophila amyloid precursor‐like protein in the development of nervous system and nonneural tissues
Authors: Li Yan , Liu Tong , Peng Yueqing , Yuan Chunyan , Guo Aike
Published: August 2004

Drosophila amyloid precursor‐like protein (APPL) is expressed extensively in the nervous system soon after neuronal differentiation. By utilizing different transgenic flies, we studied the physiological function of two APPL protein forms, membrane‐bound form (mAPPL) and secreted form (sAPPL), in neural development. We found that neither deletion nor overexpression of APPL protein altered the gross structure of mushroom bodies in the adult brain. No changes were detected in cell types and their relative ration in embryo‐derived cultures from all APPL mutants. However, the neurite length was significantly increased in mutants overexpressing mAPPL. In addition, mutants lacking sAPPL had numerous neurite branches with abnormal lamellate membrane structures (LMSs) and blebs, while no apoptosis was detected in these neurons. The abnormal neurite morphology was most likely due to the disorganization of the cytoskeleton, as shown by double staining of actin filaments and microtubules. Electrophysiologically, A‐type K+ current was significantly enhanced, and spontaneous excitatory postsynaptic potentials (sEPSPs) were greatly increased in APPL mutants lacking sAPPL. Moreover, panneural overexpression of different forms of APPL protein generated different defects of wings and cuticle in adult flies. Taken together, our results suggest that both mAPPL and sAPPL play essential roles in the development of the central nervous system and nonneural tissues. © 2004 Wiley Periodicals, Inc. J Neurobiol, 2004
Membrane electrical excitability is necessary for the free‐running larval Drosophila circadian clock
Authors: Nitabach Michael N. , Sheeba Vasu , Vera David A. , Blau Justin , Holmes Todd C.
Published: August 2004

Drosophila larvae and adult pacemaker neurons both express free‐running oscillations of period (PER) and timeless (TIM) proteins that constitute the core of the cell‐autonomous circadian molecular clock. Despite similarities between the adult and larval molecular oscillators, adults and larvae differ substantially in the complexity and organization of their pacemaker neural circuits, as well as in behavioral manifestations of circadian rhythmicity. We have shown previously that electrical silencing of adult Drosophila circadian pacemaker neurons through targeted expression of either an open rectifier or inward rectifier K+ channel stops the free‐running oscillations of the circadian molecular clock. This indicates that neuronal electrical activity in the pacemaker neurons is essential to the normal function of the adult intracellular clock. In the current study, we show that in constant darkness the free‐running larval pacemaker clock—like that of the adult pacemaker neurons they give rise to—requires membrane electrical activity to oscillate. In contrast to the free‐running clock, the molecular clock of electrically silenced larval pacemaker neurons continues to oscillate in diurnal (light–dark) conditions. This specific disruption of the free‐running clock caused by targeted K+ channel expression likely reflects a specific cell‐autonomous clock‐membrane feedback loop that is common to both larval and adult neurons, and is not due to blocking pacemaker synaptic outputs or disruption of pacemaker neuronal morphology. © 2004 Wiley Periodicals, Inc. J Neurobiol, 2005
Congenital malformations of the diaphragm: findings of the West Midlands Congenital Anomaly Register 1995 to 2000
Authors: Tonks A. , Wyldes M. , Somerset D. A. , Dent K. , Abhyankar A. , Bagchi I. , Lander A. , Roberts E. , Kilby M. D.
Published: August 2004

Objectives

To describe trends in incidence, associated anomalies, clinical outcomes and sensitivity of prenatal diagnosis for congenital malformations of the diaphragm in the West Midlands Region between 1995 and 2000.

Methods

Information was retrieved from a population‐based register of major congenital malformations in a health region of England, the West Midlands Congenital Anomaly Register (WMCAR), between 1995 and 2000.

Results

One hundred and sixty‐one confirmed cases of congenital malformations of the diaphragm were notified from 396 577 births. This gives an incidence of 4.1 per 10 000 births. After natural losses and terminations, the incidence at birth was 2.9 per 10 000 registered births. For live‐born cases, the infant mortality rate was 317 per 1000 births. 47% of the cases had additional structural or chromosomal anomalies; the infant mortality rate for these complex cases was 533 per 1000, an increased relative risk of 2.37 compared with isolated lesions. 66% of the cases were diagnosed prenatally, 51% of isolated lesions and 84% of complex cases. Fourteen prenatally diagnosed cases (12%) were false‐positives; however, 11 of these cases had other significant pathology. These 14 cases were not included in the 161 confirmed cases.

Conclusion

Congenital malformations of the diaphragm remain associated with considerable infant mortality. Most cases are now diagnosed before birth and the prognosis is adversely affected by the presence of other structural or chromosomal anomalies. This presents significant challenges for those involved in counselling the parents of affected fetuses. Copyright © 2004 John Wiley & Sons, Ltd.
Randomised trial comparing an interactive multimedia decision aid with a leaflet and a video to give information about prenatal screening for Down syndrome
Authors: Leung K. Y. , Lee C. P. , Chan H. Y. , Tang M. H. Y. , Lam Y. H. , Lee A.
Published: August 2004

Objectives

(1)To compare an interactive multimedia decision aid (IMDA) with a leaflet and a video to give information about prenatal screening for Down syndrome and (2) to determine the women's acceptance of IMDA.

Methods

Two hundred and one women were recruited from the prenatal clinic of a university teaching hospital and randomised into the intervention group (IMDA, video, and information leaflet) or the control group (video and information leaflet).

Results

There were no significant differences in the initial decision for and the final uptake of the prenatal screening test between the control and intervention groups. The proportion of women who were undecided was less than 10% in both groups. Of the women in the intervention group, 86.6% and 78.9% agreed that IMDA was user‐friendly and acceptable, respectively. Significantly more women aged <35 (88.1%) accepted IMDA than women aged >=35 (68.3%) (P = 0.030), but the logistic regression analysis did not confirm this finding after adjusting for other factors (computer knowledge and usage of computer).

Conclusion

The use of IMDA did not affect the women's overall uptake rate of the prenatal screening test for Down syndrome. More women less than 35 years accepted IMDA probably because they used computer more frequently and had more computer knowledge. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal diagnosis of Pfeiffer syndrome type II
Authors: Blaumeiser Bettina , Loquet Philip , Wuyts Wim , Nöthen Markus M.
Published: August 2004

Pfeiffer syndrome is an autosomal dominant disorder characterized by coronal craniosynostosis, midface hypoplasia, broad thumbs and great toes. On the basis of clinical findings, three subtypes have been delineated. The clinical variability of Pfeiffer syndrome as well as other causes of craniosynostosis can make a prenatal diagnosis based on sonography alone difficult. We describe a fetus in whom sonographic findings (including 3D ultrasound) suggested a Pfeiffer syndrome type II and in which subsequent molecular analysis verified the diagnosis by identifying a de novo mutation in the FGFR2 gene. To the best of our knowledge, this is the first report of a prenatal molecular diagnosis of Pfeiffer syndrome in a patient without family history. Copyright © 2004 John Wiley & Sons, Ltd.
The reporting odds ratio and its advantages over the proportional reporting ratio
Authors: Rothman Kenneth J. , Lanes Stephan , Sacks Susan T.
Published: August 2004

Purpose

The proportional reporting ratio (PRR) is the proportion of spontaneous reports for a given drug that are linked to a specific adverse outcome, divided by the corresponding proportion for all or several other drugs. The PRR is similar to the proportional mortality ratio (PMR), an old epidemiologic measure calculated from death registries and constructed in similar fashion to the PRR. The PMR has important deficiencies, however, which the PRR shares. Miettinen and Wang demonstrated that the PMR could be improved by reformulating it as an odds ratio and applying the principles of a case‐control study to the measure. In this paper, we review the problem with the PRR and show how the corresponding odds ratio represents an improvement over the PRR.

Methods

The method used is discussion and illustration by way of a hypothetical example.

Results

The PRR does not estimate relative risk. If, however, a spontaneous report database is viewed as source data for a case‐control study, the reporting odds ratio (ROR) can be used to estimate relative risk. Treating the data as source data for a case‐control study allows for further reduction of bias by the judicious choice of controls.

Conclusions

Calculating the ROR in spontaneous report databases offers advantages over the PRR. It allows for estimation of the relative risk, and focuses attention on which people or reports should be included or excluded from the control series, permitting more deliberate elimination of biases. It also highlights the inherent weaknesses in spontaneous report data, which become more evident in light of the usual principles of control selection in case‐control studies.
A retrospective, study of prescribing for erectile dysfunction in a UK population during 1997–2000: demand was neither excessive nor continuing to rise
Authors: Sullivan Frank , Donnelly Louise , Donnan Peter
Published: August 2004

Purpose

The UK NHS restricted the prescription of sildenafil to a range of clearly defined clinical situations. We describe the pattern of pharmaceutical management of erectile dysfunction (ED) during the period when the new drug was introduced and then regulated.

Methods

We studied the population of males aged over 16 (n = 121 783) who were continuously registered with 60 practices in Tayside between 1 October 1997 and 30 June 2000 using record linkage and case‐note verification. The patients' GPs allowed a research nurse to examine the records of these patients for demographic details, comorbidities and resource use.

Results

Five hundred and fifty five patients received 2493 prescriptions for alprostadil or sildenafil. The addition of an oral agent to the available therapies in 1998 did lead to a more rapid rise in prescribed treatments but this reached a plateau 3.47 per 1000 adult males per quarter after 12–15 months. Fifty eight per cent of the men had a comorbidity associated with ED. More comorbidities were found in men aged 50–69 and those living in areas of greater deprivation. Depression was a more common comorbidity in younger patients and more men from affluent areas were prescribed sildenafil following prostatectomy.

Conclusions

In the Tayside region of the UK, the introduction of an effective, acceptable oral therapy for erectile dysfunction led to a rise in prescriptions issued for ED. This rise appeared to stop after 12–15 months, perhaps partly because of the governmental restrictions imposed. Copyright © 2003 John Wiley & Sons, Ltd.
Breast cancer incidence and use of antihypertensive medication in women
Authors: González‐Pérez Antonio , Ronquist Gunnar , García Rodríguez Luis Alberto
Published: August 2004

Purpose

Breast cancer is the most common cancer in women worldwide. We attempted to investigate the association between the risk of breast cancer and use of captopril and other antihypertensive medication.

Methods

We performed a cohort study with a nested case‐control analysis using the General Practitioner Research Database (GPRD) from the UK. We obtained adjusted estimates by fitting logistic regression models.

Results

The incidence rate of breast cancer in our cohort of women aged 30–79 years was 156 per 100 000 person‐years. Overall, incidence of breast cancer among users of antihypertensive drugs was no different from the one among non‐users (odds ratio (OR): 1.0; 95% confidence interval (CI): 0.9–1.1). Captopril was not associated with a reduced risk of breast cancer (OR: 0.9; 95%CI: 0.6–1.3).

Conclusions

We did not find any clear association between antihypertensive drugs and risk of breast cancer. Similarly, captopril was not associated with a reduced risk of breast cancer risk. Copyright © 2003 John Wiley & Sons, Ltd.
Thiopurine drug adverse effects in a population of New Zealand patients with inflammatory bowel disease
Authors: Gearry Richard B. , Barclay Murray L. , Burt Michael J. , Collett Judith A. , Chapman Bruce A.
Published: August 2004

Purpose

The thiopurine drugs, azathioprine and 6‐mercaptopurine are effective in the treatment of inflammatory bowel disease (IBD). However, their use is limited by serious adverse effects that can lead to cessation of therapy. The incidence of these adverse effects has been reported to be approximately 9% but in Christchurch it was felt that the incidence was higher.

Methods

We searched our letter database to identify all patients with IBD who had received a thiopurine drug between 1996 and 2002. The case notes were then reviewed to identify those patients who had suffered an adverse effect that required cessation of the drug.

Results

From a total of 216 patients with IBD taking a thiopurine drug, 56 (25.9%) had an adverse reaction requiring cessation of the drug. Adverse effects included allergic‐type (25%), liver test abnormalities (34%), nausea/vomiting (6%), bone marrow suppression (7%), pancreatitis (7%) and other (9%). Males were significantly more likely than females to have an allergic‐type reaction (p=0.003). All adverse effects resolved with cessation of the drug, with a median of 7 days to resolution. Of the patients with liver test abnormalities on azathioprine, most were able to tolerate 6‐mercaptopurine, however challenge with 6‐mercaptopurine was not successful for most other patients.

Conclusions

In Canterbury, New Zealand, patients with IBD have a high rate of therapy‐limiting adverse effects to thiopurine drugs. There is a significant gender bias for allergic‐type adverse effects. Mechanisms for both these observations are not clear. Copyright © 2004 John Wiley & Sons, Ltd.
The use of non‐prescription medicines by general practitioner attendees
Authors: Urquhart Gordon , Sinclair Hazel K. , Hannaford Philip C.
Published: August 2004

Purpose

Against a background of increasing availability and use of non‐prescription medicines, this study set out to explore: use of such medicines by patients seeing their general practitioner (GP); frequency of GP enquiry about such use; and frequency of recommendations to use a non‐prescription medicine.

Method

Patients attending four general practices in Aberdeen, Scotland, completed separate questionnaires (before and after seeing their GP).

Results

Some 461 individuals waiting to see their GP were invited to participate: 427 (93%) completed the pre‐consultation questionnaire and 305 (71% of questionnaires issued) completed the post‐consultation questionnaire. Almost half (45%) of all participants reported using non‐prescription medicines in the 7 days prior to visiting their doctor; with 20% of the medicines purchased from non‐pharmacy retail outlets. Thirteen per cent of participants were asked about their use of non‐prescribed medicines by their GP. Eight per cent of participants were recommended to use a non‐prescription medicine by their GP.

Conclusion

Although there was a high level of recent use of non‐prescribed medicines by the general practice attenders, relatively few reported being asked about such use, or were recommended to use such medicines by their GP. Copyright © 2004 John Wiley & Sons, Ltd.