bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Mach–Zehnder LiNbO3 external modulators in microwave optical systems
Authors: Fuster J. M. , Martí J. , Candelas P.
Published: August 2002

A novel modeling approach for Mach–Zehnder electro‐optic modulators (MZ–EOMs) in microwave optical systems is presented. MZ–EOM traveling‐wave electrodes are fully characterized by an electrode transfer function (ETF) which considers internal design parameters. This ETF is approximated by the modulator electrical response that, jointly with the half‐wave voltage at dc and the optical insertion loss, are the three parameters on which the model is based. Frequency‐ and time‐domain models are provided. An excellent agreement between theoretical and experimental results validates the proposed modeling approach, useful in simulating microwave optical systems. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 85–90, 2001.
A broadband probe‐fed patch antenna for a DCS base station
Authors: Chang Fa‐Shian , Wong Kin‐Lu
Published: August 2002

This paper presents a novel broadband design of a probe‐fed patch antenna, and a constructed prototype suitable for applications in a DCS (1710–1880 MHz) cellular system base station is demonstrated. The proposed antenna has a thick air substrate for broadband operation, and is fed by a probe feed with a short probe pin, which is connected through a triangular conducting patch to one of the patch's radiating edges. By tuning the flare angle of the triangular conducting patch, good impedance matching over a wide frequency range is obtained. Details of the proposed antenna and experimental results of the constructed prototypes are presented and discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 341–343, 2001.
1H, 13C and 17O NMR spectral studies on monocyclic dioxolanes, dioxanes, dioxepanes and dioxocanes and cycloalkane‐fused (5–8‐membered) bicyclic 1,3‐dioxolanes and 1,3‐dioxanes
Authors: Pihlaja Kalevi , Nummelin Heli , Klika Karel D. , Czombos József
Published: August 2002

1H, 13C and 17O NMR data for a set monocyclic dioxolanes, dioxanes, dioxepanes, and dioxocanes and cycloalkane‐fused (5–8‐membered) bicyclic 1,3‐dioxolanes and 1,3‐dioxanes comprising 81 compounds in all are presented. This systematic configurational and conformational study addresses the deficiency in the available data regarding the conformational behaviour and, in particular, the scant 17O NMR data for 1,3‐dioxaalkanes. Many of the compounds are new and together with the known compounds measured under similar conditions they constitute a well documented compilation of spectral data suitable for addition to databases and assistance in chemical shift calculations. Copyright © 2001 John Wiley & Sons, Ltd.
Gradient‐selected versus phase‐cycled HMBC and HSQC: pros and cons
Authors: Reynolds William F. , Enriquez Raul G.
Published: August 2002

The relative sensitivity of phase‐cycled and gradient‐selected HMBC spectra is assessed. As expected, the gradient‐selected sequence is clearly superior to the phase‐cycled sequence for concentrated solutions where t1 ridges due to incomplete suppression of 1H magnetization bonded to 13C or heteroatoms are the main sources of noise in the phase‐cycled spectrum but are strongly suppressed in the gradient‐selected spectrum. However, the intensity of t1 ridges appears to be directly proportional to signal strength. Consequently, for dilute solutions, t1 ridges often provide only a minor contribution to total noise levels in phase‐cycled HMBC spectra. In this case, provided that one acquires and processes phase‐cycled HMBC spectra in the recommended mode (phase‐sensitive acquisition and mixed‐mode processing), a phase‐cycled HMBC spectrum can show about twice the signal‐to‐noise ratio of an absolute value gradient‐selected HMBC obtained in the same time. More extensive linear prediction is also possible with the phase‐cycled sequence. There are similar advantages to phase‐cycled HSQC spectra over gradient‐selected HSQC spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Saturated amine oxides: Part 4. Steric and electric field effects on the 17O NMR chemical shifts of saturated six‐membered azaheterocyclic amine oxides
Authors: Potmischil Francisc , Magiera Damian , Duddeck Helmut , Buddrus Joachim
Published: August 2002

The 17O NMR chemical shifts of 14 N‐methylpiperidine‐N‐oxides and five N‐methyltetradecahydroacridine‐N‐oxides were measured. The effects of steric factors, such as γ‐gauche and 1,3‐syn‐axial interactions of the N+—O− oxygen, on the 17O chemical shifts are discussed, and evidence for the main contribution of electrostatic interactions, rather than true steric compression, to the so‐called ‘steric effects’ on 17O chemical shifts of alcohols, ethers, sulfoxides and amine oxides is presented. For conformationally mobile compounds, the discussion of the chemical shifts is assisted by results from molecular mechanics (MM+) calculations. Copyright © 2001 John Wiley & Sons, Ltd.
Conformational analysis: Part 37. A 13C and 1H NMR and theoretical investigation of the conformational equilibrium of 2‐methylcyclohexanone oxime and of its O‐methyl ether
Authors: Ribeiro Douglas S. , Abraham Raymond J.
Published: August 2002

The free energy of the axial–equatorial equilibrium of 2‐methylcyclohexanone oxime (1E) and the corresponding O‐methyl oxime (2E) was determined by a novel curve‐fitting analysis of the temperature dependence of the carbon chemical shifts and by the vicinal proton–proton coupling constants in both polar (acetone) and non‐polar (C2Cl4) solvents. These results gave consistent values of ΔG(eq–ax) of 0.88 (±0.10) kcal mol−1 for 1E and 0.75 (±0.10) kcal mol−1 for 2E for both solvents. The complete assignments of the 1H and 13C spectra of the oxime 1E and of cyclohexanone oxime 3 and the 4‐tert‐butylcyclohexanone oxime 4 are recorded. The reduced value of the conformer free energy difference relative to the parent 2‐methylcyclohexanone (1.6 kcal mol−1) was attributed to the larger steric strain in the equatorial conformation of these oximes. This was confirmed by the analysis of the molecular geometry obtained by ab initio methods (RHF/6–31G* and B3LYP/6–31G**). Copyright © 2001 John Wiley & Sons, Ltd.
Expression of prepro‐GnRH and GnRH receptor messengers in rainbow trout ovary depends on the stage of ovarian follicular development
Authors: Uzbekova Svetlana , Lareyre Jean‐Jacques , Madigou Thierry , Davail Blandine , Jalabert Bernard , Breton Bernard
Published: August 2002

Gonadotropin‐Releasing Hormones (GnRHs) are decapeptides well known to regulate the reproductive cycle. They are expressed not only in the brain, but also in other tissues including the gonads. It is believed that they may be involved in the endocrine and paracrine regulation of the reproductive cycle. To date, two forms of GnRH have been identified in salmonids: salmon (sGnRH) and chicken II (cGnRH‐II). In the present study, the temporal expression of sGnRH‐1, sGnRH‐2, cGnRH‐II, and rtGnRH receptor genes was studied in rainbow trout ovary during the reproductive cycle according to the stages of follicular development. Using RT‐PCR coupled with Southern‐blot hybridization, sGnRH‐1, sGnRH‐2, cGnRH‐II, and rtGnRH‐R transcripts were detected in morphologically nondifferentiated ovaries as early as 55–65 days post‐fertilization and throughout all stages of vitellogenesis. Using Northern blot analysis, cGnRH‐II mRNA was detected only in immature previtellogenic ovary, whereas sGnRH mRNA was detected also during early and mid‐exogenous vitellogenesis. No sGnRH mRNA was detected at the end of vitellogenesis. In maturing pre‐ovulated ovary, sGnRH transiently reappeared before germinal vesicle breakdown (GVBD) and decreased thereafter. A few days after ovulation, a strong sGnRH mRNA expression was found in ovarian tissue as the eggs were kept in the body cavity of females. However, in females stripped just after ovulation, sGnRH mRNA levels remained low in ovary during several weeks. Fully spliced sGnRH‐1 and sGnRH‐2 messengers were mostly expressed during the reproductive cycle; however different sGnRH‐1 and sGnRH‐2 splicing variants containing intronic sequences were also detected. Some of these messengers may encode prepro‐GnRH precursors with truncated GnRH‐associated peptides. The stage‐dependent expression and different cell localization of sGnRH, cGnRH‐II, and rtGnRH‐R transcripts suggest that GnRH‐like peptides may have different roles in the paracrine regulation of ovarian follicular development. Mol. Reprod. Dev. 62: 47‐56, 2002. © 2002 Wiley‐Liss, Inc.
Comparative study of the biological activity of spermatozoa–zona pellucida binding inhibitory factors from human follicular fluid on various sperm function parameters*
Authors: Chiu P.C.N. , Ho P.C. , Ng E.H.Y. , Yeung W.S.B.
Published: August 2002

Previous studies showed that human follicular fluid (hFF) from gonadotrophin stimulated cycles contained two glycoproteins, named as ZIF‐1 and ZIF‐2, that reduced the zona binding capacity of spermatozoa. The present study showed that the spermatozoa–zona pellucida binding inhibitory activity was also present in hFF from natural cycle. Using the hemizona binding assay, the inhibitory effect of ZIF‐1 on the zona binding capacity of spermatozoa was dose‐dependent. The effect of ZIF‐2 was also dose‐dependent, in the range of 10–100 ng/ml. The inhibitory effects of both ZIF‐1 and ‐2 increased with the duration of the spermatozoa–ZIF interaction. The effect of the former was present up to 120 min incubation, whilst that of latter occurred for the first 90 min. The zona binding inhibitory effect of ZIF‐1 and ‐2 was additive when they were used together to treat the spermatozoa. The biological activity of ZIFs on other sperm parameters that might affect spermatozoa–zona pellucida binding was also investigated. ZIF‐1 did not affect the acrosomal status of human spermatozoa while ZIF‐2 significantly increased the number of acrosome reacted spermatozoa in the range of 0.1–10 μg. However, the increase in the incidence of acrosome‐reacted spermatozoa after ZIF‐2 treatment could not totally account the inhibitory effect of ZIF‐2 on zona binding. Both glycoproteins did not affect the motility of human spermatozoa. Radioactively‐labelled ZIFs bound to human spermatozoa. Unlabelled ZIF displaced the bound radioactivity of spermatozoa treated with the corresponding labelled ZIF. These suggested the presence of specific binding sites of ZIFs on human spermatozoa. Mol. Reprod. Dev. 61: 205–212, 2002. © 2002 Wiley‐Liss, Inc.
Glutamate transporter and receptor function in disorders of ammonia metabolism
Authors: Butterworth Roger F.
Published: August 2002

Disorders of ammonia metabolism including urea cycle enzymopathies, Reye Syndrome, and liver failure are associated with brain edema and severe neurological impairment. Excess blood‐borne ammonia crosses the blood‐brain barrier by diffusion as NH3 where it interacts with various cellular processes involved in neurotransmission and brain energy metabolism. Ammonia exerts a potent effect on glutamate (AMPA) receptor‐mediated neurotransmission. Ammonia also inhibits high affinity transport of glutamate by an action on astrocytic glutamate transporter expression, an action which results in increased extracellular concentrations of glutamate. Acute hyperammonemia directly activates the NMDA subclass of glutamate receptors resulting in increased intracellular Ca2+ and increased synthesis of nitric oxide and cGMP. Chronic hyperammonemia, on the other hand, results in a loss of NMDA receptor sites. Activation of NMDA receptors in acute ammonia toxicity results in depletion of ATP in brain. Neuropathologic studies in experimental animals with congenital urea cycle disorders and severe hyperammonemia reveal evidence of neuronal cell death which is excitotoxic in nature. These findings suggest that overactivation of NMDA receptors is a significant feature of acute hyperammonemic syndromes and that antagonists of these receptors or of their signal transduction pathway enzymes such as nNOS could be beneficial in the treatment of the central nervous system manifestations (encephalopathy, brain edema) which are characteristic of hyperammonemic disorders. MRDD Research Reviews 2001;7:276–279. © 2001 Wiley‐Liss, Inc.
High‐resolution isotropic 3D diffusion tensor imaging of the human brain
Authors: Golay Xavier , Jiang Hangyi , van Zijl Peter C.M. , Mori Susumu
Published: August 2002

High‐resolution cardiac‐gated 3D diffusion tensor imaging (3D‐DTI) is demonstrated in vivo for several areas of the human brain. Anatomical mapping of subcortical white matter (WM), as well as definition and identification of major WM bundles from the brainstem were performed in humans for the first time using this technique. Improved intrinsic signal‐to‐noise ratio (SNR) and relatively reduced sensitivity to physiological motion (e.g., brain pulsations) with respect to cardiac‐gated multislice acquisition are demonstrated. The advantages and weaknesses of this approach are discussed. Magn Reson Med 47:837–843, 2002. © 2002 Wiley‐Liss, Inc.
Rapid three‐dimensional diffusion MRI facilitates the study of acute stroke in mice
Authors: Xue Rong , Sawada Masahiko , Goto Shozo , Hurn Patricia D. , Traystman Richard J. , van Zijl Peter C.M. , Mori Susumu
Published: August 2002

MRI studies using mouse brain models of ischemia are becoming a valuable tool for understanding the mechanism of stroke, since transgenic models are now available. However, the small size of the mouse brain and the surgical complexity of creating ischemia in mice make it technically challenging to obtain high‐quality MRI data. Therefore, there are few reports of MRI studies in murine cerebral ischemia. In this project a newly developed rapid 3D diffusion‐weighted imaging (DWI) technique was applied to study experimental stroke in a mouse model of reversible middle cerebral artery occlusion (MCAO). Ischemic volumes were successfully delineated using this 3D whole‐brain imaging technique with high spatial (0.34 × 0.5 × 1.0 mm3 before zero‐filling) and temporal (7 min) resolution. The 3D observation revealed the characteristic evolution of stroke after transient MCAO. There was a temporarily high diffusion constant in the cortex during early reperfusion, followed by a secondary energy failure in the cortex and caudate‐putamen at 6 and 21 h of reperfusion. Magn Reson Med 46:183–188, 2001. © 2001 Wiley‐Liss, Inc.
Improved perfusion quantification in FAIR imaging by offset correction
Authors: Sidaros Karam , Andersen Irene K. , Gesmar Henrik , Rostrup Egill , Larsson Henrik B.W.
Published: August 2002

Perfusion quantification using pulsed arterial spin labeling has been shown to be sensitive to the RF pulse slice profiles. Therefore, in Flow‐sensitive Alternating‐Inversion Recovery (FAIR) imaging the slice selective (ss) inversion slab is usually three to four times thicker than the imaging slice. However, this reduces perfusion sensitivity due to the increased transit delay of the incoming blood with unperturbed spins. In the present article, the dependence of the magnetization on the RF pulse slice profiles is inspected both theoretically and experimentally. A perfusion quantification model is presented that allows the use of thinner ss inversion slabs by taking into account the offset of RF slice profiles between ss and nonselective inversion slabs. This model was tested in both phantom and human studies. Magn Reson Med 46:193–197, 2001. © 2001 Wiley‐Liss, Inc.
FLAIR imaging using nonselective inversion pulses combined with slice excitation order cycling and k‐space reordering to reduce flow artifacts
Authors: Herlihy Amy H. , Oatridge Angela , Curati Walter L. , Puri Basant K. , Bydder Graeme M. , Hajnal Joseph V.
Published: August 2002

High‐signal artifacts produced by cerebrospinal fluid (CSF) flow can adversely affect fluid‐attenuated inversion recovery (FLAIR) imaging of the brain and spinal cord. This study explores the use of a nonslice‐selective inversion pulse to eliminate CSF flow artifacts together with a technique called “K‐space Reordered by Inversion‐time for each Slice Position” (KRISP) to achieve constant contrast in a multislice acquisition. Theory shows that with this method the CSF point spread function (PSF) has a minimum at the center and attenuated side lobes, providing CSF suppression, but residual edge signals remain. The PSF for brain is only mildly attenuated and signals for extended regions are not attenuated. KRISP FLAIR sequences were assessed in 15 patients (10 brain and five spinal cord cases). The images showed reduced CSF and blood flow artifacts and higher conspicuity of the cortex, meninges, ventricular system, brainstem, and cerebellum when compared with conventional FLAIR sequences. Magn Reson Med 46:354–364, 2001. © 2001 Wiley‐Liss, Inc.
Contrast‐enhanced magnetic resonance angiography of the iliac arteries: Optimization by injection simulation
Authors: Schmidt M.A. , Britten A.J. , Tomlinson M.A. , Vig S. , Powell S. , Cleminson S. , Kerr E. , Blundell J. , Heron C.W.
Published: August 2002

Protocols for contrast‐enhanced magnetic resonance angiography (CE‐MRA) of the iliac arteries were optimized by computer simulations based on an impulse response function (IRF) of contrast agent (CA) concentration as a function of time obtained for 20 patients. Protocols with sequential, centric, and elliptical k‐space coverage, different repetition rates (5 and 10 ms), and CA doses (0.1, 0.2, and 0.3 mmol/kg b.w.) were compared in terms of signal‐to‐noise ratio (SNR), distortion of vessel profiles, and sensitivity to timing errors. IRF‐based simulations successfully characterized CA recirculation. Slow‐rate CA infusions were found to achieve relatively high enhancement. In terms of SNR, there is no advantage in increasing the repetition rate. Distortion of vessel profiles is more likely in elliptic and centric k‐space coverage. Protocols based on sequential k‐space coverage and relatively long CA infusions proved to be particularly suited to large‐FOV iliac examinations as they are relatively insensitive to timing errors. Magn Reson Med 46:365–373, 2001. © 2001 Wiley‐Liss, Inc.
Novel intravascular macromolecular MRI contrast agent with generation‐4 polyamidoamine dendrimer core: Accelerated renal excretion with coinjection of lysine
Authors: Kobayashi Hisataka , Sato Noriko , Kawamoto Satomi , Saga Tsuneo , Hiraga Akira , Ishimori Takayoshi , Konishi Junji , Togashi Kaori , Brechbiel Martin W.
Published: August 2002

One of the major limitations to macromolecular MRI contrast agents (MRI‐CAs) is their slow clearance and associated decreased excretion of gadolinium (Gd(III)). The effect of coinjecting lysine to accelerate renal excretion of a macromolecular MRI‐CA (generation‐4 PAMAM™ dendrimer (G4D‐(1B4M‐Gd)64)) was investigated. The biodistribution and urine and fecal excretion in athymic mice was evaluated with and without lysine coinjection. 3D‐dynamic‐micro‐MRI with G4D‐(1B4M‐Gd)64 was obtained with and without lysine coinjection, and the serial signal intensity (SI) change in the blood and organs was evaluated. When lysine was coinjected, urinary excretion of G4D‐(1B4M‐Gd)64 increased 5.4‐fold compared to that without lysine, resulting in decreased renal accumulation of G4D‐(1B4M‐Gd)64 from 150% to 40% injected dose per gram (P < 0.001). On dynamic MRI with G4D‐(1B4M‐Gd)64, when lysine was coinjected, the kidney‐to‐blood SI ratio was significantly lower than that obtained without lysine (P < 0.001). When lysine was coinjected, the G4D‐(1B4M‐Gd)64 was excreted from the kidney intact. Magn Reson Med 46:457–464, 2001. © 2001 Wiley‐Liss, Inc.
In vivo 1H magnetic resonance imaging and spectroscopy of the rat spinal cord using an inductively‐coupled chronically implanted RF coil
Authors: Silver X. , Ni W. Xu , Mercer E.V. , Beck B.L. , Bossart E.L. , Inglis B. , Mareci T.H.
Published: August 2002

An inductively coupled, chronically implanted short‐solenoid coil was used to obtain in vivo localized 1H NMR spectra and diffusion‐weighted images from a rat spinal cord. A 5 × 8 mm two‐turn elliptically shaped solenoid coil was implanted in rats at the site of a T‐12 vertebral‐level laminectomy. Excitation was achieved solely by a 3 × 3 cm external surface coil, and signal detection was achieved by inductively coupling the external coil to the implanted coil. The image signal‐to‐noise ratio (SNR) obtained with the inductively‐coupled implanted coil was compared with that obtained using a linear or a quadrature external surface coil. The implanted coil provided a gain by over a factor of 3 in SNR. The implanted coil was used to measure localized 1H spectra in vivo at the T13/L1 spinal‐cord level within a 1.85 × 1.85 × 4.82 mm (16.5 μL) volume. With 256 averages, a ∼3‐s repetition delay and respiratory gating, a high‐quality spectrum was acquired in 13 min. In addition, water translational diffusion was measured in three orthogonal directions using a stimulated‐echo imaging sequence, with a short echo time (TE), to produce a quantitative map of diffusion in a rat spinal cord in vivo. Magn Reson Med 46:1216–1222, 2001. © 2001 Wiley‐Liss, Inc.
Sensory potentials evoked by tactile stimulation of different indentation velocities at the finger and palm
Authors: Baba Masayuki , Simonetti Stefano , Krarup Christian
Published: August 2002

Previous studies suggest that the rate of indentation of a tactile probe determines which skin mechanoreceptors are activated. To further investigate this possibility, indentations of 300 μm at velocities of 100 (T100) and 400 μm/ms (T400) were applied to the tip (FT) and the proximal phalanx of digit III (PP) and the thenar eminence (Pm) of ten healthy volunteers, and compared with responses after electrical stimulation at the FT. Compound sensory action potentials (CSAPs) were recorded from the median nerve through needle electrodes at the wrist and elbow. The maximal sensory conduction velocities (SNCVs) between wrist and elbow were similar with electrical and T400 stimulation, but on average were 15% lower with T100 stimulation (P < 0.001). With both indentation velocities, SNCVs were similar regardless of stimulation sites. Amplitudes of tactile CSAPs with FT stimulation were 1–2 μV at T400 and 0.3–0.4 μV at T100. The CSAP areas evoked by T100 stimulation showed a reduction from fingertip to proximal finger to palm (P < 0.05–0.005), whereas those obtained with T400 stimulation showed a reduction only at the palm (P < 0.05). The results support previous studies indicating that fast indentation at 400 μm/ms activated deeply placed Pacinian corpuscles as well as superficially situated Meissner corpuscles, whereas slower indentation at 100 μm/ms activated primarily Meissner corpuscles. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1213–1218, 2001
A parallel machine replacement model
Authors: McClurg Tim , Chand Suresh
Published: August 2002

This paper considers a finite horizon parallel machine replacement problem where a fixed number of machines is in operation at all times. The operating cost for a machine goes up as the machine gets older. An older machine may have to be replaced by a new one when its operating cost becomes too high. There is a fixed order cost associated with the purchase of new machines. Machine purchase prices and salvage values may depend on the period in which they were purchased. The objective is to find a replacement plan that minimizes the total discounted cost over the problem horizon. We believe that the costs in our model are more commonly observed in practice than those previously used in the literature. The paper develops properties of optimal solutions and an efficient forward‐time algorithm to find an optimal replacement plan. A dominance property is developed that further limits the options to be considered, and a simple forecast horizon result is also presented. Future research possibilities are mentioned. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 275–287, 2002; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/nav.10012
A branch and bound algorithm for the minimum storage‐time sequencing problem
Authors: Detti P. , Pacciarelli D.
Published: August 2002

The minimum storage‐time sequencing problem generalizes many well‐known problems in combinatorial optimization, such as the directed linear arrangement and the problem of minimizing the weighted sum of completion times, subject to precedence constraints on a single processor. In this paper we propose a new lower bound, based on a Lagrangian relaxation, which can be computed very efficiently. To improve upon this lower bound, we employ a bundle optimization algorithm. We also show that the best bound obtainable by this approach equals the one obtainable from the linear relaxation computed on a formulation whose first Chvàtal closure equals the convex hull of all the integer solutions of the problem. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 313–331, 2001
Continuation of invariant subspaces
Authors: Dieci L. , Friedman M. J.
Published: August 2002

In this work we consider implementation and testing of an algorithm for continuation of invariant subspaces. Copyright © 2001 John Wiley & Sons, Ltd.
Buckling analysis of rotationally periodic structures using shell element with relative degrees of freedom
Authors: Cen Z. , Li J. , Lie S. T.
Published: August 2002

By considering the characteristics of deformation of rotationally periodic structures subjected to rotationally periodic loads, the periodic structure is divided into several identical substructures in this paper. If the structure is really periodic but not axisymmetric, the number of the substructures can be defined accordingly. If the structure is axisymmetric (special in the case of the periodic), the structure can be divided into any number of substructures. It means, in this case, the number of substructures is independent of the number of buckling waves. The degrees of freedom (DOFs) of joint nodes between the neighbouring substructures are classified as master and slave ones. The stress and strain conditions of the whole structure are obtained by solving the elastic static equations for only one substructure by introducing the displacement constraints between master and slave DOFs. The complex constraint method is used to get the bifurcation buckling load and mode for the whole rotationally periodic structure by solving the eigenvalue problem for only one substructure without introducing any additional approximation. Finite element (FE) formulation of shell element of relative degrees of freedom (SERDF) in the buckling analysis is then derived. Different measures of tackling internal degrees of freedom for different kinds of buckling problems and different stages of numerical analysis are presented. Some numerical examples are given to illustrate the high efficiency and validity of this method. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluations of certain hypersingular integrals on interval
Authors: Du Qi‐Kui
Published: August 2002

In this paper, we investigate a hypersingular integral on an interval. The definition of Hadamard's finite‐part integrals and some of its properties are given. Some numerical methods on approximate computation of the finite‐part integrals are constructed. The new method is very simple, easy to implement, reliable, and above all, not affected by the location of singular point. Some numerical experiments are carried out using the current formulae, and numerical results show that the current methods are feasible and effective. Copyright © 2001 John Wiley & Sons, Ltd.
Application of two‐state M‐integral for analysis of adhesive lap joints
Authors: Lee Yongwoo , Goo Nam Seo , Im Seyoung
Published: August 2002

With the aid of the two‐state M‐integral and finite element analysis, the asymptotic solution in terms of the complete eigenfunction expansion is obtained for adhesive lap joints. The notch stress intensity is introduced to characterize the singular stress field near the notch vertex of adhesive lap joints. The proposed scheme enables us to extract the intensity of each eigenfunction term from the far field data without resort to special singular elements at the vertex. It turns out that a weak stress singularity is not negligible around the vertex when it exists in addition to the major singularity. For a thin adhesive layer, there exist two asymptotic solutions: one is the inner solution approaching the eigenfunction solution for the vertex at which the adherend meets with the adhesive and the other is intermediate solution represented by the eigenfunction series that would be obtained in the absence of the adhesive layer. An appropriate guideline for choosing the geometric parameters in designing the adhesive lap joints, particularly the overlap length or the size of the adhesive zone, is suggested from the viewpoint of minimizing the notch stress intensity. Copyright © 2001 John Wiley & Sons, Ltd.
The least‐squares meshfree method
Authors: Park Sang‐Hoon , Youn Sung‐Kie
Published: August 2002

A new efficient meshfree method is presented in which the first‐order least‐squares method is employed instead of the Galerkin's method. In the meshfree methods based on the Galerkin formulation, the source of many difficulties is in the numerical integration. The current method, in this respect, has different characteristics and is expected to remove some of the integration‐related problems. It is demonstrated through numerical examples that the present formulation is highly robust to integration errors. Therefore, numerical integration can be performed with great ease and effectiveness using very simple algorithms. Copyright © 2001 John Wiley & Sons, Ltd.
How networks undergird the lateral capability of an organization—where the work gets done
Authors: Galbraith Jay , Downey Diane , Kates Amy
Published: August 2002

While, for most managers, the overall structure of their organization is a given, those
managers—wittingly or unwittingly—create the interpersonal and interfunctional links through which
the work takes place. The effectiveness of those links can be strengthened by a deliberate encouragement of
networks. There are six useful ways to support such networks—through focused development of
co‐location, communities of practice, annual meetings and retreats, training programs, rotational
assignments, and technology and e‐coordination. And these efforts become even more effective when reward
structures support them. © 2002 by the authors
Single cell discretization of O(kh2 + h4) for the estimates of ${\partial u}\over{\partial n}$ for the two‐space dimensional quasi‐linear parabolic equation
Authors: Mohanty R. K. , Jain M. K. , Kumar Dinesh
Published: August 2002

In this article, new stable two‐level explicit difference methods of O(kh2 + h4) for the estimates of ${\partial u}\over{\partial n}$ for the two‐space dimensional quasi‐linear parabolic equation are derived, where k > 0 and h > 0 are grid sizes in time and space directions, respectively. We use a single computational cell for the methods, which are applicable to the problems both in cartesian and polar coordinates. The proposed methods have the simplicity in nature and employ the same marching type technique of solution. Numerical results obtained by the proposed methods for several different problems were compared with the exact solutions. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17: 250–261, 2001
Stability of adsorber resins under mechanical compression and ultrasonication
Authors: Breitbach M. , Bathen D. , Schmidt‐Traub H. , Ebener H.
Published: August 2002

Different adsorber and ion exchange resins have been sonicated with ultrasound of different frequencies in a fixed bed. Afterwards, the sonicated particles were investigated by scanning electron and light microscopy. Also, different mechanical properties, like fracture load, maximum flattening and Young's modulus were measured in compression tests and compared to the results of the ultrasonication experiments. Cavitational collapses cause cracks in resins with a high fracture load and a high Young's modulus as well as a low deformation at fracture. Complete destruction of adsorbent particles due to acoustic cavitation is observed with particles of low fracture loading and low Young's modulus. No or only little destruction is observed with particles which inhibit both sufficient strength and deformation properties. On the basis of these findings it is concluded that resin particles with optimum resistance to ultrasound show both a sufficient fracture load as well as high mechanical flexibility. Copyright © 2002 John Wiley & Sons, Ltd.
Screening for trisomy 21 in twin pregnancies in the first trimester: does chorionicity impact on maternal serum free β‐hCG or PAPP‐A levels?
Authors: Spencer Kevin
Published: August 2002

In a study of 180 twin pregnancies I have examined the distribution of maternal serum free β‐human chorionic gonadotrophin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A), in addition to fetal nuchal translucency thickness (NT), in twins classified as monochorionic or dichorionic, based on ultrasound appearance at 10–14 weeks of gestation. In 45 monochorionic and 135 dichorionic twin pregnancies the median MoM free β‐hCG was not significantly different (1.00 vs 1.01), whilst that for PAPP‐A was lower (0.89 vs 1.01) but again with no statistical significance. Previous reports of an increased fetal NT in monochorionic twins pregnancies could not be confirmed (1.03 vs 1.00). It is concluded that the existing pseudo risk twin correction algorithm is appropriate for both monochorionic and dichorionic twins in providing accurate first trimester risks for trisomy 21. Copyright © 2001 John Wiley & Sons, Ltd.
The diagnostic performance of cytogenetic investigation in amniotic fluid cells and chorionic villi
Authors: Los Frans J. , van den Berg Cardi , Wildschut Hajo I. J. , Brandenburg Helen , den Hollander Nicolette S. , Schoonderwaldt Ernst M. , Pijpers Leen , Jan H. Galjaard Robert , Van Opstal Diane
Published: August 2002

First‐trimester chorionic villus sampling has not reached the popularity of second‐trimester amniocentesis in prenatal cytogenetic diagnosis, in contrast to initial expectations. We investigated whether a difference inthe diagnostic performances of cytogenetic investigation in amniotic fluid (AF) cells and chorionic villi in favour of AF‐cells might justify this. Diagnostic performance was measured as laboratory failure rate, karyotype quality (G‐band score, rate of follow‐up samples, rate of wrong diagnoses), and karyotype representativity (rate of follow‐up samples, rate of wrong diagnoses).

From 1993–1999, 11 883 AF‐samples were investigated (AF‐cells). In chorionic villi, short term culture preparations solely were karyotyped from 1993–1996 (n=3499) (STC‐villi), short and long‐term culture preparations simultaneously provided a sufficient amount of tissue being available from 1997 onwards (n=1829) ((STC+LTC)‐villi). Laboratory failure rates were the same after amniocentesis (0.40%) and chorionic villus sampling (0.50%). G‐band scores (mean±SD) were equal in AF‐cells (373±38.1) and LTC‐villi (364±32.6) but significantly lower in STC‐villi (311±34.6) (p=0.001). Follow‐up sampling rates because of quality reasons were the same in AF‐cells (0.14%), STC‐ villi (0.13%) and (STC+LTC)‐villi (0.11%). Two wrong diagnoses turned up among AF‐cells. Follow‐up sampling rates because of representativity reasons differed significantly between AF‐cells (0.10%), (STC+LTC)‐villi (1.31%), and STC‐villi (1.99%) (p<0.001). However, the ratios of the total numbers of follow‐up samples and uncertain or abnormal cytogenetic results in STC, and (STC+LTC)‐villi at cytogenetic risks ⩾3% (0.132 and 0.160, respectively) were equal to that in AF‐cells at risks <3% (0.155). Two wrong diagnoses were made in STC‐villi.

Diagnostic performance improved in the rank order of STC‐villi, (STC+LTC)‐villi and AF‐cells. At cytogenetic risks ⩾3%, (STC+LTC)‐villi showed a diagnostic performance equal to that in AF‐cells. This might justify a selective use of chorionic villus sampling. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of new poly(amide–imide)s derived from trimellitylimido‐L‐phenylalanine
Authors: Mallakpour Shadpour E , Hajipour Abdol‐Reza , Habibi Sakineh
Published: August 2002

N‐Trimellitylimido‐L‐phenylalanine was prepared from the reaction of 1,2,4‐benzenetricarboxylic anhydride with L‐phenylalanine in N,N‐dimethylformamide solution at refluxing temperature. The direct polycondensation reaction of the monomer imide‐diacid with 4,4′‐diaminodiphenylsulfone, 4,4′‐diaminodiphenylmethane, 1,4‐phenylenediamine, 1,3‐phenylenediamine, 2,4‐diaminotoluene, 4,4′‐diaminodiphenylether and benzidine was carried out in a medium consisting of triphenyl phosphite, N‐methyl‐2‐pyrrolidone, pyridine and calcium chloride. The resulting poly(amide–imide)s, PAIs, having inherent viscosities of 0.21–0.45 dlg−1 were obtained in high yield. All of the above compounds were fully characterized by IR spectroscopy and elemental analyses. The optical rotation of all PAIs has also been measured. Some structural characterization and physical properties of these new optically active PAIs are reported.

© 2001 Society of Chemical Industry
Effect of solvent evaporation rate on surface composition in fluoro‐copolymer/acrylate‐copolymer blend films
Authors: Akiyama Saburo , Tsukiji Nikako , Akiba Isamu , Inoue Minoru , Kano Yoshihisa
Published: August 2002

The relationship between the surface composition and the rate of solvent evaporation (R) in blend films of poly(vinylidene fluoride‐co‐hexafluoroacetone) (P(VDF‐HFA)) and poly(2‐ethylhexyl acrylate‐co‐acrylic acid‐co‐vinyl acetate) (P(2EHA‐AA‐VAc)) has been investigated. P(VDF‐HFA), a low‐surface tension component, was concentrated on the surface when R was relatively high. In contrast, when R was relatively low, P(2EHA‐AA‐VAc), a low‐density component, was concentrated on the surface. Therefore, it is speculated that the factors dominating surface enrichment in polymer blends were changed from surface tension differences to density differences between the components when R was decreased. In addition, the affinity between components and substrate strongly affects the dominant factors determining the surface composition.

© 2001 Society of Chemical Industry
In‐situ self reinforced polyimide for film materials
Authors: Fan Haojun , Gu Yi , Xie Meili
Published: August 2002

A novel polyimide (PI) with mesogenic units was synthesized by the reaction between the pendent hydroxyl group of PI and the epoxy group of a liquid crystalline (LC) compound in the presence of N,N‐dimethylaniline at 120–130 °C. As a result, a novel in‐situ self‐reinforced PI film materials was obtained. The macromolecular reaction between the hydroxyl group and epoxy group was investigated by a model reaction. The properties of PI were studied by WAXD, DSC and polarized optical microscopy, and the results indicate that the polyimides with mesogenic units exhibit a smectic phase, the mesogenic units level influencing the side‐chain crystallinity, and also the thermal and mechanical properties of the polymers; the enhanced PI films possess good solubility, higher thermal stability, higher tensile strength and modulus.

© 2001 Society of Chemical Industry
Studies of cure kinetics of polyisoimide by differential scanning calorimetry in the solid state
Authors: Kim Young Jun , Son Gum Im , Kim Ji‐Heung
Published: August 2002

Detailed kinetic studies of the thermal imidization of polyisoimide based upon 4,4′‐oxydianiline and 4,4′‐oxydiphthalic anhydride by differential scanning calorimetry are described. Both isothermal and dynamic methods have been used to obtain kinetic parameters and a phenomenological rate equation for estimating the degree of imidization as a function of time. The thermal imidization of polyisoimides in the solid state showed a maximum degree of imidization that can be achieved at a given isothermal temperature, probably due to the diffusion controlled characteristics of reactions near vitrification. That the reaction stopped near to the point of vitrification was considered when developing a phenomenological rate equation for thermal imidization of polyisoimide in the solid state. The thermal imidization is well described by modified first order kinetics with an activation energy of 170–181 kJ mol−1 and a pre‐exponential factor of 4.1 × 1013 s−1.

© 2002 Society of Chemical Industry
A measure for evaluating the effectiveness of teen pregnancy prevention programs
Authors: Somers Cheryl L. , Johnson Stephanie A. , Sawilowsky Sholmo S.
Published: August 2002

Teen pregnancy prevention has been a major component of the school sex education curriculum for the past two decades, as well as the focus of many community agency programs. A difficulty in evaluating these programs is the lack of instruments in measuring teens' attitudes and intentions regarding teenage pregnancy. The sixteen‐item Teen Attitude Pregnancy Scale (TAPS) was developed for this purpose. It is based on a model of (a) Future Orientation, (b) Realism About Child Rearing, (c) Personal Intentions, and (d) Sexual Self‐efficacy. Overall, the TAPS demonstrated good internal consistency and concurrent validity for the samples considered here. Additionally, exploratory factor analysis revealed evidence of validity for this four‐factor model of teens' attitudes toward pregnancy. © 2002 Wiley Periodicals, Inc.
Reactivity of alkanols and aryl alcohols towards tetrachloroaurate(III) in sodium acetate–acetic acid buffer medium
Authors: Pal Biswajit , Sen Pratik K. , Sen Gupta Kalyan K.
Published: August 2002

The oxidative behaviour and relative reactivities of three alkanols and 11 aryl alcohols towards gold(III) in sodium acetate–acetic acid buffer were studied. The reactions are first order with respect to [Au(III)] and in each [R1R2CHOH]. Both H+ and Cl− ions retard the rate of reactions. The reactions obey the following rate expression:

AuCl4−, AuCl3(OH2) and AuCl3(OH)− are the reactive species of gold(III) and the reactivity follows the order AuCl3(OH)− > AuCl3(OH2) > AuCl4−. The activation parameters of the reactions were calculated. Alkanols react with gold(III) in the order ethanol > methanol > 2‐propanol. The unsubstituted benzyl alcohol reacts with gold(III) at a faster rate than benzhydrol. The pseudo‐first‐order rate constants in the oxidations of aryl alcohols follow the order NO2 > H > Cl > OMe. The reactions occur via C—H bond cleavage and through the intermediate formation of free radicals. Copyright © 2001 John Wiley & Sons, Ltd.
Role of peroxophosphate intermediates in reactions of tris(4‐nitrophenyl) phosphate and phenyl phosphoro‐chloridate with alkaline hydrogen peroxide
Authors: Foroudian Houshang J. , Gillitt Nicholas D. , Bunton Clifford A. , Yatsimirsky Anatoly K.
Published: August 2002

Reaction of alkaline hydrogen peroxide with tris(4‐nitrophenyl) phosphate generates ca 1.5 equiv. of 4‐nitrophenol per mole of substrate with no evidence of build‐up of an intermediate, and reaction of bis(4‐nitrophenyl) phosphate anion is too slow to give a product. The initially formed bis(4‐nitrophenyl) peroxophosphate is assumed to decompose to the phosphate ester by reaction with H2O2 or to eliminate 4‐nitrophenoxide ion with the formation of a transient cyclic peroxophosphate. Reaction of phenyl phosphorochloridate anion with HO2− does not give phenoxide ion by this intramolecular reaction. Semi‐empirical and ab initio simulations indicate that elimination of aryloxide ion from an aryl peroxophosphate should generate a cyclic rather than an open‐chain peroxophosphate. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and chemical structural analysis of nitroxyl‐radical‐incorporated poly(acrylic acid/lactide/ϵ‐caprolactone) copolymers
Authors: Lang Meidong , Chu Chih‐Chang
Published: August 2002

The goal of this research is to synthesize biodegradable polymers that would have nitroxyl radical biological functions. Linear aliphatic polyesters were chosen as the starting materials. The hydroxyl‐terminated polylactide/ϵ‐caprolactones (PBLC‐OHs) were first synthesized by melt ring‐opening copolymerization in the presence of benzyl alcohol and stannous octoate. PBLC‐OHs were used as the precursor for the synthesis of double bond‐functionalized polylactide/ϵ‐caprolactones (PBLC‐Mas) by reacting the hydroxyl end groups of PBLC‐OH with maleic anhydride in melt at 130 °C. Acrylic acid/lactide/ϵ‐caprolactone graft copolymers (PBLCAs) were then successfully carried out by the radical copolymerization of acrylic acid and PBLC‐Ma initiated by azobisisobutyronitrile. Finally, nitroxyl radicals [4‐amino‐2,2,6,6‐tetramethylpiperidine‐1‐oxy (TAM)] were incorporated into the carboxylic acid sites of the acrylic acid/lactide/ϵ‐caprolactone copolymer (TAM‐PBLCA) by reacting TAM with PBLCA in the presence of N,N′‐carbonyl diimidazole. A high content of TAM was incorporated into the PBLCA copolymer. The polymers synthesized were characterized by 1H and 13C NMR, Fourier transform infrared spectroscopy, and electron paramagnetic resonance spectra. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4214–4226, 2001
Synthesis of polyisocyanide derived from phenylalanine and its temperature‐dependent helical conformation
Authors: Yamada Yuki , Kawai Tadashi , Abe Jiro , Iyoda Tomokazu
Published: August 2002

Screw‐sense‐selective polymerization of the chiral isocyanide monomers derived from phenylalanine with NiCl2 as a catalyst in methanol to yield helical‐conjugated polyisocyanide was investigated with respect to the thermal stability of its helical conformation. Poly(1‐tert‐butoxycarbonyl‐2‐phenylethyl isocyanide) (poly1c) took a stable helical conformer independent of the polymerization temperature. In poly(1‐ethoxycarbonyl‐2‐phenylethyl isocyanide) (poly2c), which had slightly smaller side groups, the helical conformation was thermally destabilized. The specific rotation and circular dichroism of poly2c prepared at temperatures greater than 40 °C were considerably depressed in comparison with the values for poly2c prepared at or below room temperature. Additionally, poly2c prepared at low temperatures exhibited reversible temperature‐dependent specific rotation and circular dichroism, whereas poly1c showed few changes. It is suggested that polyisocyanide derived from phenylalanine takes various helical conformers (i.e., from tightly to loosely coiled helices), the thermal stability of which depends on the size of the side group. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 399–408, 2002
Free‐radical copolymerization of styrene and m‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate studied by 1H NMR kinetic experiments
Authors: Barner Leonie , Barner‐Kowollik Christopher , Davis Thomas P.
Published: August 2002

The free‐radical copolymerization of m‐isopropenyl‐α,α′‐dimethylbenzyl isocyanate (TMI) and styrene was studied with 1H NMR kinetic experiments at 70 °C. Monomer conversion vs time data were used to determine the ratio kp × kt−0.5 for various comonomer mixture compositions (where kp is the propagation rate coefficient and kt is the termination rate coefficient). The ratio kp × kt−0.5 varied from 25.9 × 10−3 L0.5 mol−0.5 s−0.5 for pure styrene to 2.03 × 10−3 L0.5 mol−0.5 s−0.5 for 73 mol % TMI, indicating a significant decrease in the rate of polymerization with increasing TMI content in the reaction mixture. Traces of the individual monomer conversion versus time were used to map out the comonomer mixture composition drift up to overall monomer conversions of 35%. Within this conversion range, a slight but significant depletion of styrene in the monomer feed was observed. This depletion became more pronounced at higher levels of TMI in the initial comonomer mixture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1064–1074, 2002
Terminology of kinetics, thermodynamics, and mechanisms of polymerization
Authors: Penczek Stanislaw
Published: August 2002

This article, after a short introduction, written by a coordinator of the International Union of Pure and Applied Chemistry (IUPAC) Project devoted to the Terminology of the Kinetics, Thermodynamics, and Mechanisms of Polymerization presents the Provisional Document prepared by the IUPAC Macromolecular Division (Commission Nomenclature). It contains 95 entries, from “activated monomer polymerization” to “zwitterionic polymerization.” © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1665–1676, 2002