bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical modeling and experimental investigation of resonance properties of microwave capacitors
Authors: Semouchkina Elena , Cao Wenwu , Mittra Raj , Lanagan Michael 
Published: August 2002

AbstractThe finite‐difference time‐domain (FDTD) field simulations have been employed to visualize standing‐wave patterns in single‐layer, rectangular, planar capacitors and capacitor chips. These patterns are used for the analysis of the resonant mode types, and for the determination of the resonance frequencies. The results of simulation are experimentally verified by measuring the S‐parameter spectra. In addition, we show that the dimensions of the capacitor plates can be optimized in order to maximize the first resonant frequency of the capacitor, rendering it useful for high‐frequency applications. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 54–60, 2001.
Design criteria for increasing the bandwidth–efficiency product of GaAs p–i–n photodetectors
Authors: Torrese G. , Huynen,and I. , Vander Vorst A. 
Published: August 2002

AbstractUsing commercial and homemade simulation tools, this letter investigates how the geometrical and technological parameters of the p–i–n junction, particularly the p+‐ and n+‐regions, influence the electrical and optical performances of GaAs p–i–n lumped and traveling‐wave photodetectors (TWPDs). It is concluded that, for TWPDs, the electrical bandwidth and quantum efficiency can be optimized nearly separately as a function of the parameters of the p‐, i‐, and n‐regions. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 150–155, 2001.
Modeling Mach–Zehnder LiNbO3 external modulators in microwave optical systems
Authors: Fuster J. M. , Martí J. , Candelas P. 
Published: August 2002

AbstractA 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

AbstractThis 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

Abstract1H, 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractGonadotropin‐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

AbstractPrevious 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

AbstractDisorders 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

AbstractHigh‐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

AbstractMRI 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

AbstractPerfusion 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

AbstractHigh‐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

AbstractProtocols 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

AbstractOne 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

AbstractAn 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.