bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rearrangements of Carbocation Sulfinate Ion Pairs
Authors: Herpers Ekkehard , Kirmse Wolfgang 
Published: July 2007

AbstractThe chirality of alkyl p‐toluenesulfinates and of 18O‐labeled p‐toluenesulfinate ions was utilized to study the stereoselectivity of ion‐pair recombinations. The diastereomers of 2‐norpinyl (13), 2‐norbornyl (16), 2‐methyl‐2‐norbornyl (25), and exo‐4‐protoadamantyl (34) p‐toluenesulfinates were rearranged in formamide or trifluoroacetic acid (TFA). Solvolysis competed to a minor extent. Predominant return of the carbocations to the oxygen atoms of ArSO2− was observed if the isomeric p‐toluenesulfinates persisted (kinetic control). On repeated ionization (thermodynamic control), sulfones were eventually formed. With the exception of 25, 1,2 shifts of the p‐toluenesulfinate anion proceed faster than oxygen exchange. The migration origin of the carbocation returns preferentially to the oxygen atom of ArSO2− from which the migration terminus departed. Conversely, the sulfinate anion discriminates between positions 1 and 2 of the symmetrical, bridged 2‐norbornyl cation in favor of the carbon atom from which it departed. The selectivity of ion‐pair recombination decreases in the order 2‐norpinyl ≈ 4‐protoadamantyl > 2‐norbornyl > 2‐methyl‐2‐norbornyl, i.e., with increasing stability of the carbocation. The rearrangements of 13 and 34 proved to be more selective in TFA at 0°C than in formamide at 120–130°C. The p‐toluenesulfinates 13 and 34 were compared with the analogous tosylates and 3,5‐dinitrobenzoates. More oxygen scrambling was observed with less nucleophilic anions (tosylate ≫ p‐toluenesulfinate > 3,5‐dinitrobenzoate). Oxygen scrambling is also enhanced if the anion migrates over a longer distance (2‐norpinyl → exo‐2‐norbornyl vs. 2‐norpinyl → endo‐2‐norbornyl).
From Pagodanes to Homologous, Non‐Pentagonal Dodecahedranes
Authors: Pinkos Rolf , Weiler Andreas , Voss Torsten , Weber Klaus , Wahl Fabian , Melder Johann‐Peter , Fritz Hans , Hunkler Dieter , Prinzbach Horst 
Published: July 2007

AbstractHomo‐ and bishomododecahedral cage molecules with one and two OCO (OCH2) linkers installed into the parent pentagonal framework and featuring diverse functionalization patterns have been made available from pagodane precursors via highly expeditious synthetic sequences. The enforced geometrical changes with respect to molecular curvature, olefinic pyramidalization, transannular π,π‐distance as well as to the chemical reactivity particularly of the unsaturated homododecahedranes are generally in good agreement with expectations based on calculations (MM2). In the appreciably pyramidalized monohomododecahedradiene skeleton 40 the non‐parallel π‐bonds are ca. 2.9 (3.1) Å [Φ = ca. 20 (32)°, MM2], in the bishomododecahedradiene skeleton 55 the perfectly syn‐periplanar π‐bonds 2.81 Å apart (Φ = 18.2°, X‐ray crystal structure).
Synthesis and Application of Iso(thio)cyanate‐Functionalized Calix[4]arenes
Authors: van Wageningen André M. A. , Snip Erwin , Verboom Willem , Reinhoudt David N. , Boerrigter Harold 
Published: July 2007

AbstractAminocalix[4]arenes 7–12 react with triphosgene and thiophosgene to the corresponding iso(thio)cyanate‐functionalized calix[4]arenes 13–20. Carbamate‐ (21–25) and ureasubstituted calix[4]arenes (26,27) can be obtained via isocyanatocalix[4]arenes using a one‐pot synthesis starting from the corresponding aminocalix[4]arenes in moderate to good yields. Isothiocyanate‐functionalized calix[4]arenes 16, 18 react selectively with amines to the corresponding thioureas 28–31 in 59–83% yield. Reaction of isothiocyanate‐functionalized calix[4]arenes 16, 19, 20 with cavitands 34, 38 gives 2:2 products 42–45 in 35–42% yield.
Ligands for EuIII, FeIII, SrII, and UO Based on CMPO‐Functionalized Resorcinarene Cavitands; Synthesis and Extraction
Authors: Boerrigter Harold , Verboom Willem , Reinhoudt David N. 
Published: July 2007

AbstractPartially functionalized cavitands (7a–d) have been synthesized starting from the tetrakis(bromomethyl)cavitand 6. New cavitand‐based cation ligands, with one to three carbamoylmethylphosphane oxide (CMPO) moieties (11a–d), were prepared in good (66–90%) yields. The ligands 11a–d extract EuIII, but do so less effectively than the tetra‐CMPO cavitand 1. The decreasing number of CMPO groups which result in decreasing extraction percentages for EuIII, also decrease the selectivity of EuIII over that of FeIII, SrII, and UO. There is a difference in extraction behavior, determined by radio‐tracer experiments, between the distal and proximal disubstituted ligands, 11b and 11c, respectively. The extraction constants for the 1:1 complex of 11b and 11c with Eu(picrate)3 are Kex = 6.7 · 108 M−4 and 3.7 · 109 M−4, respectively.
Synthesis and Polymerization of Liquid Crystals Containing Vinyl and Mercapto Groups
Authors: Lub Johan , Broer Dirk Jan , van den Broek Nel 
Published: July 2007

AbstractLiquid‐crystalline monomers containing two vinyl groups, two mercapto groups, or a 1:1 combination of the two have been synthesized and characterized in terms of their mesomorphic properties. These monomers can be photopolymerized in situ in an appropriate ratio of vinyl and mercapto groups to form highly ordered liquid‐crystalline main‐chain polymers. During polymerization in the nematic phase the appearance changes from clear in the highly aligned birefringent state to opaque. This effect is probably due to scattering which is caused by the disturbance of the macro alignment as a result of the polymerization shrinkage and/or phase separation. In some cases, the reaction mixtures pass from the nematic to the crystalline state which results in a reduction in the degree of conversion and also in a change in the microcrystalline state. Crystallization can be suppressed by promoting asymmetry of the molecular structure which leads to a higher degree of conversion.
Photochemical and Thermal Cycloaddition Reactions of 3‐Thioxoandrosta‐1,4‐dien‐17‐one with Electron‐Deficient Alkynes
Authors: Möller Stephanie , Weiß Dieter , Beckert Rainer 
Published: July 2007

Abstract3‐Thioxoandrosta‐1,4‐dien‐17‐one (4) reacts with acetylene dicarboxylic acid esters to form novel spiro compounds of the thiine type (6a, 6b), whereas with free acids, such as acetylene dicarboxylic acid and propiolic acid, the spirocyclic O,S‐acetals 7a and 7b are obtained. This study demonstrates that the cycloaddition reaction is promoted by photochemical and also thermal activation.
Multi‐Arm 1,2,3‐Thiadiazole Systems
Authors: Al‐Smadi Mousa , Meier Herbert 
Published: July 2007

AbstractBenzene derivatives 2a–c with 6, 4, and 3 side chains bearing terminal 1,2,3‐thiadiazole rings, respectively, have been prepared. Alkaline cleavage of 2a–c led to the corresponding alkynethiolates 6a–c, which were trapped by electrophiles such as benzyl bromide or iodomethane. The method provides an alternative to the thermal or photochemical cleavage of 1,2,3‐thiadiazoles to thioketenes, which react further with nucleophiles.
Direct Iodination of Sydnones and Their Cycloadditions to Form 5‐Iodopyrazoles
Authors: Dumitraşcu Florea , Drâghici Constantin , Dumitrescu Denisa , Tarko Laszlo , Râileanu Dan 
Published: July 2007

AbstractDirect iodination of sydnones has been achieved using iodine monochloride, leading to yields in excess of 80%. The products were subjected to 1,3‐dipolar cycloaddition reactions affording novel 5‐iodopyrazoles.
Estimation of fusiform intracranial aneurysm growth by serial magnetic resonance imaging
Authors: Dispensa Bradley P. , Saloner David A. , Acevedo‐Bolton Gabriel , Achrol Achal S. , Jou Lianger‐der , McCulloch Charles E. , Johnston S. Claiborne , Higashida Randall T. , Dowd Christopher F. , Halbach Van V. , Ko Nerissa U. , Lawton Michael T. , Martin Alastair J. , Quinnine Nancy , Young William L. 
Published: July 2007

AbstractPurposeIntracranial aneurysm (IA) growth is associated with increased morbidity. We sought to establish a quantitative computational method based on contrast‐enhanced MR angiography (CE‐MRA) for estimating aneurysmal volume changes over time.Materials and MethodsComputational volume calculations were tested against a distensible phantom. Untreated patients with IA were followed longitudinally with annual MRI. Maximal linear dimensions along the longitudinal axis and two transverse axes were determined by visual review of maximum intensity projection (MIP) data, and aneurysm volume was approximated as (length × width × height)/2. Averages of the visual approximations were compared to the lumenal volume as determined with a computational algorithm using the MRI data.ResultsMRI‐based measurements accurately represented volume changes in the phantom (R2 = 0.97, Y = 1.06x + 271 CM3). In the clinical study there were a total of 11 intervals of one‐year follow‐up in six patients (mean ± SD, age = 53 ± 20 years). The raw one‐year growth using the computational volume was 9% ± 17%. The corresponding value for the averaged measurement of the reviewers was 8% ± 14%. Neither the mean values nor the SDs were different (P = .51).ConclusionMRI‐based measurement of aneurysm volume appears feasible for longitudinal studies of aneurysm natural history. J. Magn. Reson. Imaging 2007;26:177–183. © 2007 Wiley‐Liss, Inc.
Motion corrected free‐breathing delayed‐enhancement imaging of myocardial infarction using nonrigid registration
Authors: Ledesma‐Carbayo Maria J. , Kellman Peter , Arai Andrew E. , McVeigh Elliot R. 
Published: July 2007

AbstractPurposeTo develop and test an automatic free‐breathing, delayed enhancement imaging method with improved image signal‐to‐noise ratio (SNR).Materials and MethodsThe proposed approach uses free‐breathing, inversion‐recovery single‐shot fast imaging with steady precession (FISP) delayed‐enhancement with respiratory motion compensation based on nonrigid image registration. Motion‐corrected averaging is used to enhance SNR.ResultsFully automatic, nonrigid registration was compared to previously validated rigid body registration that required user interaction. The performance was measured using the variance of edge positions in intensity profiles through the myocardial infarction (MI) enhanced region and through the right ventricular (RV) wall. Measured variation of the MI edge was 1.16 ± 0.71 mm (N = 6 patients; mean ± SD) for rigid body and 1.08 ± 0.76 mm for nonrigid registration (no significant difference). On the other hand, significant improvement (P< 0.005) was found in the measurements at the RV edge where the SD was 2.06 ± 0.56 mm for rigid body and 0.59 ± 0.22 mm for nonrigid registration.ConclusionThe proposed approach achieves delayed enhancement images with high resolution and SNR without requiring a breathhold. Motion correction of free‐breathing delayed‐enhancement imaging using nonrigid image registration may be implemented in a fully automatic fashion and performs uniformly well across the full field of view (FOV). J. Magn. Reson. Imaging 2007;26:184–190. © 2007 Wiley‐Liss, Inc.
Effect of multislice acquisition on T1 and T2 measurements of articular cartilage at 3T
Authors: Watanabe Atsuya , Boesch Chris , Obata Takayuki , Anderson Suzanne E. 
Published: July 2007

AbstractPurposeThe aim of this study was to investigate the effect of magnetization transfer on multislice T1 and T2 measurements of articular cartilage.Materials and MethodsA set of phantoms with different concentrations of collagen and contrast agent (Gd‐DTPA2−) were used for the in vitro study. A total of 20 healthy knees were used for the in vivo study. T1 and T2 measurements were performed using fast‐spin‐echo inversion‐recovery (FSE‐IR) sequence and multi‐spin‐echo (MSE) sequence, respectively, in both in vitro and in vivo studies. We investigated the difference in T1 and T2 values between that measured by single‐slice acquisition and that measured by multislice acquisition.ResultsRegarding T1 measurement, a large drop of T1 in all slices and also a large interslice variation in T1 were observed when multislice acquisition was used. Regarding T2 measurement, a substantial drop of T2 in all slices was observed; however, there was no apparent interslice variation when multislice acquisition was used.ConclusionThis study demonstrated that the adaptation of multislice acquisition technique for T1 measurement using FSE‐IR methodology is difficult and its use for clinical evaluation is problematic. In contrast, multislice acquisition for T2 measurement using MSE was clinically applicable if inaccuracies caused by multislice acquisition were taken into account. J. Magn. Reson. Imaging 2007;26:109–117. © 2007 Wiley‐Liss, Inc.
Lipomatous hypertrophy of the interatrial septum associated with fatty replacement of the ventricular myocardium: A case report
Authors: Pérez Arroyuelos Irune , Berástegui Imaz María , Canteli Padilla Begoña , Urresola Olabarrieta Arantza 
Published: July 2007

AbstractLipomatous hypertrophy of the interatrial septum (LHIS) is a rare benign entity characterized by the excessive fat deposition in the interatrial septum with typical sparing of the fossa ovalis. We report a case of a 61‐year‐old woman with an incidentally found LHIS associated with fatty replacement of the ventricular myocardium and epicardial mediastinal lipomatosis diagnosed by computed tomography (CT) and MRI. J. Magn. Reson. Imaging 2007;26:152–154. © 2007 Wiley‐Liss, Inc.
Role of MRI in investigating the effects of elastic compression stockings on the deformation of the superficial and deep veins in the lower leg
Authors: Downie Steven P. , Firmin David N. , Wood Nigel B. , Thom Simon A. , Hughes Alun D. , Wolfe John N.H. , Xu X. Yun 
Published: July 2007

AbstractPurposeTo evaluate the potential of MRI to investigate the mechanical effects of compression stockings on the veins of the lower limb.Materials and MethodsThe right calves of eight healthy volunteers were imaged in the prone position, with and without the presence of a compression stocking. Cross‐sectional areas of all peroneal and posterior tibial veins, both saphenous veins, and any sufficiently large superficial veins were segmented in all subjects at mid‐calf level in both cases. Variation in cross‐sectional area along the axis of the great saphenous vein and a peroneal vein was also examined in three subjects.ResultsThe mean cross‐sectional area reduction was found to be greater in the deep veins (64%) than in the superficial veins (39%). Deep‐vein cross‐sections were generally elliptical, while superficial veins were approximately circular. Significant axial fluctuations were found in the cross‐sectional areas.ConclusionMRI offers a precise source of data on the mechanical effects of lower‐limb compression. Ultrasound (US) may be more cost‐effective, but the data acquired are less comprehensive. Future biomechanical studies of lower‐limb compression should make use of MRI. J. Magn. Reson. Imaging 2007;26:80–85. © 2007 Wiley‐Liss, Inc.
Dynamic imaging of swallowing in a seated position using open‐configuration MRI
Authors: Honda Yasutoshi , Hata Nobuhiko 
Published: July 2007

AbstractPurposeTo assess the feasibility of dynamic MRI of swallowing in a seated position using an open‐configuration MRI scanner, and to compare its capacity for motion analysis around the pharyngeal wall with that of videofluorography.Materials and MethodsSix healthy individuals (four women and two men, mean age = 31.4 ± 7.5 years) were examined with an open‐configuration MRI system using a fast spoiled gradient‐recalled echo (SPGR) sequence. Dynamic imaging was performed while the subjects were in a seated position after they swallowed oral contrast medium from a cup. An oral and maxillofacial radiologist measured the motion of six structures: the hyoid bone (HB), larynx (LX), upper oropharynx (UOP), lower oropharynx (LOP), pharyngoesophageal segment (PES) behind the vocal folds, and upper esophagus (ESO). The measured motions were compared with reported values from videofluorography‐based observations.ResultsOpen‐configuration MRI depicted the anatomic structures related to swallowing (lip, tongue, soft palate, mandible, pharynx, HB, LX, and PES), and the course of the mylohyoid muscle (MM). The vertical and anteroposterior displacements of these structures did not differ significantly from those measured by videofluorography.ConclusionDynamic imaging of swallowing using open‐configuration MRI provides image information comparable to that obtained from videofluorography. J. Magn. Reson. Imaging 2007;26:172–176. © 2007 Wiley‐Liss, Inc.
Differentiation of intraductal papillary mucinous neoplasms from other pancreatic cystic masses: Comparison of multirow‐detector CT and MR imaging using ROC analysis
Authors: Song Su Jin , Lee Jeong Min , Kim Young Jun , Kim Se Hyung , Lee Jae Young , Han Joon Koo , Choi Byung Ihn 
Published: July 2007

AbstractPurposeTo compare the diagnostic performance of multirow‐detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses.Materials and MethodsA total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis.ResultsThe Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted κ values indicate good agreement (κ = 0.61) between observers for MDCT, and excellent agreement (κ = 0.82) for MRI.ConclusionPancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas. J. Magn. Reson. Imaging 2007;26:86–93. © 2007 Wiley‐Liss, Inc.
Iron‐oxide labeling of hematogenous macrophages in a model of experimental autoimmune encephalomyelitis and the contribution to signal loss in fast imaging employing steady state acquisition (FIESTA) images
Authors: Oweida Ayman J. , Dunn Elizabeth A. , Karlik Stephen J. , Dekaban Gregory A. , Foster Paula J. 
Published: July 2007

AbstractPurposeTo determine the contribution of blood‐derived macrophages to the signal loss observed in MR images of inflammatory lesions in experimental autoimmune encephalomyelitis (EAE).Materials and MethodsA relapsing‐remitting form of EAE was induced in transgenic mice that express enhanced green fluorescent protein (EGFP) specifically in hematopoietic cells of the myelomonocytic lineage. Animals were injected with Feridex, a superparamagnetic iron oxide (SPIO) nanoparticle, 24 hours prior to in vivo MRI. MRI was performed using a 1.5T whole‐body scanner; a high‐performance, custom‐built gradient coil insert; and a 3D steady‐state free precession (SSFP) imaging pulse sequence. Comparisons were made between MR images and corresponding anti‐GFP and Perl's Prussian blue (PPB)‐stained brain sections.ResultsMR images revealed the presence of discrete regions of signal loss throughout the brains of EAE animals that were administered Feridex. Histological staining showed that regions of signal loss on MR images corresponded anatomically with regions of PPB‐ and GFP‐positive cells.ConclusionThis experiment provides the first direct evidence that macrophages of hematogenous origin are labeled with SPIO after intravenous administration of Feridex, and contribute to the regions of signal loss detected in MR images of EAE brain. J. Magn. Reson. Imaging 2007;26:144–151. © 2007 Wiley‐Liss, Inc.
Interactive effects of salinity and potassium availability on growth, water status, and ionic composition of Hordeum maritimum
Authors: Hafsi Chokri , Lakhdhar Abdelbasset , Rabhi Mokded , Debez Ahmed , Abdelly Chedly , Ouerghi Zeineb 
Published: July 2007

AbstractThe interactive effects of salinity and potassium (K+) availability on biomass production, water status, and ionic composition were investigated in Hordeum maritimum, an annual grass growing natively on saline soils. Plants were grown for 7 weeks on Hewitt nutrient solution supplied with NaCl (0, 100, 150, 200, and 300 mM) combined with low (0.232 mM) or high (5.8 mM) K+ levels. Independent of potassium availability, dry matter of both roots and shoots decreased consistently with increasing NaCl levels in the culture medium, in association with a significant reduction of the shoot water content. This salt‐induced growth reduction did not result from a restriction of K+ nutrition, since H. maritimum expressed similar growth under both low and high K+ supply. NaCl decreased shoot K+ concentrations. This effect was more pronounced in plants grown at high K+ supply than in plants grown at low K+ supply. This result suggests that the absorption systems were strongly selective for K+, and that this selectivity was enhanced by salt.
Mercury accumulation and resistance to mercury stress in Rumex induratus and Marrubium vulgare grown in perlite
Authors: Moreno‐Jiménez Eduardo , Peñalosa Jesús M. , Esteban Elvira , Carpena‐Ruiz Ramón O. 
Published: July 2007

AbstractPlants of Rumex induratus and Marrubium vulgare, collected in the mining area of Almadén, were transferred to pots and grown for 2 months using perlite as substrate and treated with soluble mercury (Hg) in the applied nutrient solution. Mercury resistance, Hg bioaccumulation, and some stress biomarkers were investigated in both plant species. Mercury concentration increased in both plant species in response to Hg supply, but R. induratus was more effective in Hg accumulation. Rumex induratus and M. vulgare showed higher [Hg]shoot‐to‐[Hg]root ratios than other plant species. Mercury in the growth medium perlite was also investigated, distinguishing soluble, available, and total amounts of Hg in the medium. At the lower doses, one half of the applied Hg was retained by perlite. Rumex induratus decreased the available Hg fraction in perlite more than M. vulgare. The bioaccumulation factor ([Hg]plant/[Hg]available) was similar in both species and similar as found in previous field studies. Plant growth, water content, and chlorophyll concentration, and nutrient translocation were reduced in both plant species by the Hg. Rumex induratus showed higher resistance and Hg‐accumulation capacity than M. vulgare, due to the accumulation of thiols in roots and the absence of a lipid oxidative response.