bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the articular cartilage of the knee joint with vastly undersampled isotropic projection reconstruction steady‐state free precession imaging
Authors: Kijowski Richard , Lu Aiming , Block Walter , Grist Thomas
Published: June 2006

Purpose

To determine the feasibility of the vastly undersampled isotropic projection reconstruction steady‐state free precession (VIPR‐SSFP) sequence for evaluating the articular cartilage of the knee joint.

Materials and Methods

A magnetic resonance (MR) examination of the knee was performed on 33 subjects using a GE 1.5T scanner and a phased‐array extremity coil. VIPR‐SSFP, proton density‐weighted fast spin‐echo (PD‐FSE), fat‐suppressed T2‐weighted fast spin‐echo (T2‐FSE), and three‐dimensional fat‐suppressed spoiled gradient recall‐echo (SPGR) sequences were performed on three asymptomatic volunteers and 10 patients with osteoarthritis of the knee joint. Signal‐to‐noise efficiency, and contrast‐to‐noise ratio (CNR) measurements were calculated for all sequences and compared with the use of paired t‐tests. The VIPR‐SSFP sequence was then performed on 20 consecutive patients who were undergoing a routine MR examination of the knee.

Results

The cartilage signal‐to‐noise efficiency of the VIPR‐SSFP sequence was not significantly different from that of the PD‐FSE and SPGR sequences. The cartilage signal‐to‐noise efficiency of the VIPR‐SSFP sequence was significantly higher (P < 0.05) than that of the T2‐FSE sequence. The VIPR‐SSFP sequence produced images with significantly higher (P < 0.05) CNR between cartilage and synovial fluid than the PD‐FSE and SPGR sequences, and significantly higher (P < 0.05) CNR between cartilage and subchondral bone than the T2‐FSE sequence. The VIPR‐SSFP sequence allowed excellent visualization of the articular cartilage of the knee joint in all subjects. All articular cartilage defects identified on the PD‐FSE, T2‐FSE, and SPGR images were well visualized on the VIPR‐SSFP images.

Conclusion

VIPR‐SSFP images had high cartilage signal‐to‐noise efficiency and high CNR between cartilage and adjacent synovial fluid and subchondral bone; therefore, the sequence is well suited for evaluating the articular cartilage of the knee joint. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Novel diffusion anisotropy indices: An evaluation
Authors: Wang Jiun‐Jie , Chao Tsi‐chian , Wai Yau‐Yau , Hsu YuanYu
Published: June 2006

Purpose

To systematically evaluate diffusion anisotropy (DA) using newly defined indices based on the diffusion deviation and mean diffusivity approach.

Materials and Methods

Measures of amplitude, area, and volume of the DA index (DAI) were measured and compared with regard to their sensitivity to changes in DA, susceptibility to noise in the original diffusion‐weighted (DW) images, and contrast‐to‐noise ratio (CNR) in homogenous regions. Simulations were performed under different levels of noise and DA. Human DTI data were acquired from eight normal volunteers.

Results

Indices of area and volume measures provided improved resolution for characterizing the DA compared to the eigenvalue ratio. The amplitude measure showed consistent performances with good CNR and less susceptibility to noise in the original data.

Conclusion

These indices are rotationally invariant without the requirement of eigenvalue sorting. At low anisotropy, all indices have a similar CNR. For larger DA, the first index (the deviation tensor divided by the DT) shows improved sensitivity, contrast‐to‐noise ratio (CNR), and noise immunity compared to the other indices. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Proton and sodium MRI assessment of fluid level in calf tissue
Authors: Zuo Chun S. , Villafuerte Rosemond A. , Henry Michael E. , Butman Michelle , Dobbins Robert L. , He Yiwu , Orban Barbara S. , Cayetano Kenroy , Wang Liqun , Brown Andrew P. , Nunez Derek J. , Brown John , Renshaw Perry F.
Published: June 2006

Purpose

To investigate the feasibility of using 1H and 23Na MRI to detect fluid levels in the lower leg muscle.

Materials and Methods

Proton and sodium MRI was applied to detect body fluid levels in the lower leg muscles of 18 healthy young male subjects at 3T and 4T. The paradigms under investigation were a postural change from sitting upright to lying supine, and saline infusion.

Results

We found that the average proton MR signal in gastrocnemius and soleus muscles were reduced following the postural change by 3.5% ± 1.4% (P < 0.05) and rose following saline infusion by 3.7% ± 0.9% (P < 0.01). More dramatically, the sodium MR signal decreased by 7.1% ± 1.2% (P < 0.01) following the postural change and increased following saline infusion by 12% ± 3.8% (P < 0.05). The ratio of intra‐ to extracellular fluid levels was 1.6 ± 0.5 for the subjects based on the acquired proton and sodium data.

Conclusion

Our results indicate that proton and sodium MRI can be used to assess fluid levels in the lower extremities, and this technique may be applied to evaluate fluid retention. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Fast chiral separation by ligand‐exchange HPLC using a dynamically coated monolithic column
Authors: Schmid Martin G. , Schreiner Karin , Reisinger Daniela , Gübitz Gerald
Published: June 2006

The preparation and application of dynamically coated ligand‐exchange chromatography phases for enantioseparation is described. The phases were prepared by pumping a solution of N‐decyl‐L‐4‐hydroxyproline, N‐hexadecyl‐L‐4‐hydroxyproline, or N‐2‐hydroxydodecyl‐L‐4‐hydroxyproline through a commercially available monolithic RP‐18 column. These coatings are stable against desorption for months at ambient temperature when aqueous mobile phases are used. The columns were applied to the chiral separation of amino acids, glycyl dipeptides and diastereomeric dipeptides, and tripeptides. The chiral selector can be removed or changed easily by washing the column with ACN or methanol. Ultrafast separations in the range of seconds were achieved using high flow rates.
Residue analysis of 500 high priority pesticides: Better by GC–MS or LC–MS/MS?
Authors: Alder Lutz , Greulich Kerstin , Kempe Günther , Vieth Bärbel
Published: June 2006

This overview evaluates the capabilities of mass spectrometry (MS) in combination with gas chromatography (GC) and liquid chromatography (LC) for the determination of a multitude of pesticides. The selection of pesticides for this assessment is based on the status of production, the existence of regulations on maximum residue levels in food, and the frequency of residue detection. GC–MS with electron impact (EI) ionization and the combination of LC with tandem mass spectrometers (LC–MS/MS) using electrospray ionization (ESI) are identified as techniques most often applied in multi‐residue methods for pesticides at present. Therefore, applicability and sensitivity obtained with GC–EI–MS and LC–ESI–MS/MS is individually compared for each of the selected pesticides. Only for one substance class only, the organochlorine pesticides, GC‐MS achieves better performance. For all other classes of pesticides, the assessment shows a wider scope and better sensitivity if detection is based on LC–MS. © 2006 Wiley Periodicals, Inc.
“Paradoxical Kinesis” is not a Hallmark of Parkinson's disease but a general property of the motor system
Authors: Ballanger Bénédicte , Thobois Stéphane , Baraduc Pierre , Turner Robert S. , Broussolle Emmanuel , Desmurget Michel
Published: June 2006

Although slowness of movement is a typical feature of Parkinson's disease (PD), it has been suggested that severely disabled patients remained able to produce normal motor responses in the context of urgent or externally driven situations. To investigate this phenomenon (often designated “paradoxical kinesis”), we required PD patients and healthy subjects to press a large switch under three main conditions: Self Generated, produce the fastest possible movement; External Cue, same as Self Generated but in response to an acoustic cue; Urgent External Cue, same as External Cue with the switch controlling an electromagnet that prevented a ball falling at the bottom of a tilted ramp. Task difficulty was equalized for the two experimental groups. Results showed that external cues and urgent conditions decreased movement duration (Urgent External Cue < External Cue < Self Generated) and reaction time (Urgent External Cue < External Cue). The amount of reduction was identical in PD patients and healthy subjects. These observations show that paradoxical kineses are not a hallmark of PD or a byproduct of basal ganglia dysfunctions, but a general property of the motor system. © 2006 Movement Disorder Society
Recurrent LRRK2 (Park8) mutations in early‐onset Parkinson's disease
Authors: Hedrich Katja , Winkler Susen , Hagenah Johann , Kabakci Kemal , Kasten Meike , Schwinger Eberhard , Volkmann Jens , Pramstaller Peter P. , Kostic Vladimir , Vieregge Peter , Klein Christine
Published: June 2006

Mutations in LRRK2 (leucine‐rich repeat kinase 2) have been associated with autosomal dominant Parkinson's disease (PD) and cluster in several 3′ exons of the gene. The majority of mutations have been detected in late‐onset cases (age at onset >50 years). We screened 5 of the 51 exons of LRRK2 that previously have been reported to harbor mutations in 98 early‐onset and 42 late‐onset PD patients. We identified two mutations (c.4321C>T, c.6055G>A) in three early‐onset patients. Screening of an additional 220 early‐onset PD patients for these mutations revealed another mutation carrier. In conclusion, LRRK2 mutations need to be considered also in early‐onset PD. © 2006 Movement Disorder Society
13C NMR chemical shifts of carbonyl groups in substituted benzaldehydes and acetophenones: substituent chemical shift increments
Authors: Patterson‐Elenbaum Stephanie , Stanley John T. , Dillner Debra K. , Lin Shirley , Traficante Daniel
Published: June 2006

13C NMR Substituent chemical shift (SCS) increments have been determined for the carbonyl carbon of a variety of substituted benzaldehydes and acetophenones. The 13C NMR chemical shift of the carbonyl carbon can be predicted for many di‐ and trisubstituted benzaldehydes and acetophenones through simple additivity of the SCS increments. The magnitude and sign of the SCS increments have been explored using Hartree‐Fock 6‐31G* calculations to determine the natural atomic charges of the carbonyl carbon. When a substituent capable of intermolecular hydrogen bonding is present, deviations from additivity on the order of 2 ppm are observed in dilution experiments; deviations of up to 6 ppm can result from intramolecular hydrogen bonding. Copyright © 2006 John Wiley & Sons, Ltd.
Alignment effect of attapulgite on the mechanical properties of poly(vinyl alcohol)/attapulgite nanocomposite fibers
Authors: Peng Zhiqin , Chen Dajun
Published: June 2006

Poly(vinyl alcohol) (PVA)/attapulgite (AT) nanocomposite fibers have been prepared by wet spinning. The morphology and mechanical properties of the modified PVA fibers have been characterized with transmission electron microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), birefringence measurements, and mechanical testing. The PVA/AT nanocomposite fibers show much higher tensile strength, initial modulus, and work to break than pure PVA fibers with the same draw ratio. SEM observations demonstrate that the AT nanorods can align orderly along the fiber axis by stretching and have good adhesion to the fiber matrix. The results of birefringence measurements prove that the modified fibers have higher orientation than pure PVA fibers after stretching. The results of DSC analysis indicate that the crystallinity of the PVA fibers can be increased by the addition of AT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1995–2000, 2006
Elastic and piezoelectric properties of gadolinium calcium oxoborate GdCa4O(BO3)3 crystal
Authors: Pawlaczyk C. , Markiewicz E. , Kłos A. , Hofman W. , Pajączkowska A.
Published: June 2006

Gadolinium calcium oxoborate, GdCa4O(BO3)3 (GdCOB), single crystals were grown by the Czochralski technique. The orientation of crystal was precisely determined. To estimate the complete matrices of the elastic (13) and piezoelectric (10) coefficients measurements of the complex electrical impedance for 26 suitably chosen crystal cuts were made. The step‐by‐step procedure of this estimation is described in details and the possible errors are calculated and discussed. The results are compared with the published data of other authors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Physical properties of CdS thin films grown by pulsed laser ablation on conducting substrates: effect of the thermal treatment
Authors: Vigil‐Galán O. , Vidal‐Larramendi J. , Escamilla‐Esquivel A. , Contreras‐Puente G. , Cruz‐Gandarilla F. , Arriaga‐Mejía G. , Chavarría‐Castañeda M. , Tufiño‐Velázquez M.
Published: June 2006

Structural, morphological and optical properties of CdS films, deposited by the pulsed laser ablation technique on SnO2:F/glass substrates, were studied as a function of time deposition. Up to our knowledge the properties of these films grown onto conducting polycrystalline substrates have not been reported before. The photoluminescence measurements showed the existence of an exciton peak at room temperature, as an indication of good crystalline quality of the layers. A thermal treatment was applied to the samples in a 100 mT Ar atmosphere at 400 °C for 30 min after the deposition of a CdCl2 layer on them. Films characterization was carried out through X‐ray diffraction, photoluminescence and atomic force microscopy measurements. The structural, optical and morphological properties as a function of growth parameters are presented and discussed. Thermal treatment makes uniform the grain size in the samples, with a tendency to increase the grain size average. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Smooth anodic TiO2 nanotubes: annealing and structure
Authors: Macak Jan M. , Aldabergerova Saule , Ghicov Andrei , Schmuki Patrik
Published: June 2006

The influence of an annealing process on the structure and the composition of smooth high aspect ratio TiO2 nanotube layers, grown by anodization of Ti in viscous glycerol electrolytes containing fluorides, is reported. XRD and HRTEM measurements demonstrate that the as‐formed high aspect ratio TiO2 nanotubes have an amorphous structure that can be entirely transformed to single phase – anatase – upon thermal annealing at 450 °C for 3 hours. XPS and EDX analyses furthermore show that annealing process is accompanied with an elimination of fluoride ions (present in the structure after formation). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Contribution of dislocations to carrier recombination and transport in highly excited ELO and HVPE GaN layers
Authors: Malinauskas T. , Jarašiūnas K. , Aleksiejunas R. , Gogova D. , Monemar B. , Beaumont B. , Gibart P.
Published: June 2006

Nonequilibrium carrier dynamics has been investigated in ELO and HVPE grown GaN layers in a wide temperature and excitation range by using the time‐resolved picosecond FWM technique. Carrier lifetime in the samples at 300 K increased up to 2.8–5.1 ns in accordance with the decreasing threading dislocation density from 4 × 107 cm–2 (ELO) to mid 106 cm–2 in HVPE layers. At T < 100 K, the hyperbolic shape of FWM kinetics indicated carrier density dependent radiative lifetimes, which gradually decreased at lower temperatures to a few hundreds of ps. The dominance of bimolecular recombination in HVPE layers at 10–40 K was demonstrated by the exposure characteristic of FWM, that has shown a sublinear growth of carrier density with excitation, N ∝ I1/2. Numerical fitting of the set of FWM kinetics at various T confirmed the temperature dependence of bimolecular recombination coefficient B ∝ T–1.5 and provided its value B = 2 × 10–11 cm3/s at 300 K and 3.2 × 10–9 cm3/s at 9 K. The measured bipolar diffusion coefficients allowed determination of carrier diffusion length of 0.8–1 μm at 300 K and its dependence on dislocation density and temperature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Undoped and rare‐earth doped GaN quantum dots on AlGaN
Authors: Hori Yuji , Andreev Thomas , Florian Thomas , Bellet‐Amalric Edith , Le Si Dang Daniel , Tanaka Mitsuhiro , Oda Osamu , Daudin Bruno
Published: June 2006

We study the self organized growth of GaN quantum dots deposited by molecular beam epitaxy on AlxGa1–xN, with x varying between 1 and 0.21. As a result of the specific strain relaxation mechanism of AlxGa1–xN on AlN, it is found that dots can be formed for an Al content as low as about 30%. Monopolar devices have been realized by depositing Schottky contacts on n‐type doped Al0.5Ga0.5N. Finally, electroluminescence of Eu‐doped GaN quantum dots embedded in n‐type Al0.5Ga0.5N has been demonstrated, emphasizing the potentialities of such an active layer for room temperature visible light emission. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman and transmission electron microscopy characterization of InN samples grown on GaN/Al2O3 by molecular beam epitaxy
Authors: Arvanitidis J. , Katsikini M. , Ves S. , Delimitis A. , Kehagias Th. , Komninou Ph. , Dimakis E. , Iliopoulos E. , Georgakilas A.
Published: June 2006

Raman spectroscopy and transmission electron microscopy were employed to study the vibrational properties and the microstructure of epitaxially grown InN films on GaN/Al2O3 templates. The variations of the InN lattice constants, as deduced by electron diffraction analysis, along with the red‐shifted E22 mode frequency reveal that InN films exhibit residual tensile stress, strongly dependent on the epilayer growth temperature. Threading dislocations are the dominant structural defects in the films, having a density in the order of 109–1010 cm–2. Profile analysis of the E22 Raman peak by means of the Spatial Correlation Model provides useful information concerning the effective mean length for free phonon propagation (L), which is a measure of the structural quality of the samples. In all the studied samples, L monotonically increases with decreasing threading dislocation density of pure screw and mixed type character. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of AlN nanowires by metal organic chemical vapour deposition
Authors: Cimalla V. , Foerster Ch. , Cengher D. , Tonisch K. , Ambacher O.
Published: June 2006

AlN nanowires with a diameter of 20 nm were grown stochastically by the vapour‐liquid‐solid (VLS) method. At low temperatures below 1000 °C the Kirkendall effect during the alloying of aluminium and the catalyst resulted in the formation of three‐dimensional nanostructures like lamellas and nano flowers. The high temperatures above 1000 °C, which are necessary to grow the nanowires complicate the control of their formation. Small catalyst droplets of 20 nm diameter are not stable due to their evaporation. Thus, in contrast to the classical approach to grow a single nano wire out of one droplet, we grew dense networks of nanowires inside larger 3D structures with diameters up to 5 µm. Depending on the growth temperature and the droplet geometry the nanowires inside of these networks are connected by angles of 90° (“cubic”) or 120° (“hexagonal”). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low density GaN quantum dots on AlGaN
Authors: Pakuła K. , Bożek R. , Surowiecka K. , Stępniewski R. , Wysmolek A. , Baranowski J. M.
Published: June 2006

A new method of the growth of low‐density GaN quantum dots on AlGaN by MOVPE is reported. The method bases on in‐situ etching of the AlGaN surface in the presence of silane (SiH4) and subsequent growth of randomly nucleated GaN nano‐crystallites. Investigation of successive growth stages with atomic force microscopy (AFM) shows that density of the GaN crystallites is of the order of 108 cm–2. Micro‐photoluminescence (µPL) measurements show sharp emission lines originating from single quantum dots without any artificial masks or mesa structures. This gave unique possibility for advanced studies on optical and electrical properties of single GaN quantum dots in AlGaN. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of high‐In‐content InGaN multiple quantum disk nanocolumns on Si(111) by RF plasma‐assisted molecular‐beam epitaxy
Authors: Kouno Tetsuya , Kikuchi Akihiko , Kishino Katsumi
Published: June 2006

Self‐organized InxGa1–xN nanocolumns with high‐In‐contents of x = 0.86–1.0 and In0.86Ga0.14N/ In0.79Ga0.21N multiple quantum disk (MQD) nanocolumns were successfully grown on Si(111) substrates by rf plasma‐assisted molecular beam epitaxy. The InxGa1–xN nanocolumns showed room‐temperature photoluminescence (RT‐PL) emission and the emission peak wavelength varied from 1500 to 1920 nm with increasing In content from 0.86 to 1.0. The In0.86Ga0.14N/In0.79Ga0.21N MQD nanocolumns showed a satellite peak in X‐ray diffraction spectra that indicates the growth of a good periodic structure. RT‐PL emission was also observed and the emission peak wavelength shifted from 1450 to 1620 nm with changing In0.86Ga0.14N well layer thickness from 1.5 to 3.0 nm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and role of ultrathin AlN layers for improving optical activation of rare earth implanted GaN
Authors: Wójtowicz T. , Gloux F. , Ruterana P. , Nouet G. , Bodiou L. , Braud A. , Lorenz K. , Alves E.
Published: June 2006

In this work we carry out characterization of GaN implanted with Tm and Eu ions by scanning and transmission electron microscopy. Structural investigation is supported by optical measurements. We have investigated samples implanted at room temperature with different energies (150–300 keV) and fluences (1–7 × 1015 at/cm2). High temperature annealing was performed at 1200 °C and 1300 °C with the GaN surface protected by a 10nm thick AlN cap grown by MOCVD prior to the implantation. Direct implantation in GaN, results in the formation of a high density of stacking faults in the damaged surface layer and a nanocrystalline surface layer when a critical dose is exceeded. Implanting through the AlN capping layer prevents the formation of the nanocrystalline layer even for high fluences but the stacking faults are still generated. The AlN cap also protects the surface during high temperature annealing. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transition energies and Stokes shift analysis for In‐rich InGaN alloys
Authors: Schley P. , Goldhahn R. , Winzer A. T. , Gobsch G. , Cimalla V. , Ambacher O. , Rakel M. , Cobet C. , Esser N. , Lu H. , Schaff W. J.
Published: June 2006

The absorption and emission properties of In‐rich InGaN alloys were studied by spectroscopic ellipsometry and photoluminescence spectroscopy, respectively. Films grown on a GaN buffer layer show a much sharper increase of the imaginary part of the dielectric function around the band gap and a slightly reduced Stokes shift compared to layers grown directly on AlN buffers. It is attributed to a reduced electron concentration and improved structural quality of the films. By fitting the third derivatives of the dielectric functions up to 9.5 eV we determine for the first time the compositional dependences (bowing param‐eters) of the transition energies for at least four critical points of the band structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN/AlGaN superlattices for optoelectronics in the mid‐infrared
Authors: Guillot F. , Monroy E. , Gayral B. , Bellet‐Amalric E. , Jalabert D. , Gérard J.‐M. , Dang Le Si , Tchernycheva M. , Julien F. H. , Monnoye S. , Mank H.
Published: June 2006

In this work we discuss the optical properties of a GaN/Al0.11Ga0.89N multiple‐quantum‐well structure grown on 4H‐SiC by plasma‐assisted molecular‐beam epitaxy. Photoluminescence lines related to the fundamental and excited electronic levels are identified, in good agreement with simulations of the electronic structure. Temperature dependence studies reveal an anomalous behaviour with quenching of the e1–hh1 while the e2–hh1 line becomes dominant at room temperature. This behaviour could be explained by the increasing thermal population of the e2 state and the higher radiative efficiency of the e2–hh1 transition compared to the e1–hh1 transition due to the intense electric field in the well. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray diffraction reciprocal lattice space mapping of a‐plane AlGaN on GaN
Authors: Tsuda Michinobu , Furukawa Hiroko , Honshio Akira , Iwaya Motoaki , Kamiyama Satoshi , Amano Hiroshi , Akasaki Isamu
Published: June 2006

In this study, the anisotropic strain in a‐plane AlGaN on GaN was investigated by X‐ray diffraction (XRD) analysis using AlGaN/GaN heterostructure grown on r‐plane sapphire. An a‐plane GaN layer is compressively strained, particularly in the m‐axis direction. According to XRD reciprocal lattice space mapping, the AlGaN layer was strained under tensile stress and grown almost coherently to the underlying GaN layer. The tensile stress in the AlGaN layer in the c‐axis direction is approximately 1.7 times larger than that in the m‐axis direction. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum transport in high mobility AlGaN/GaN 2DEGs and nanostructures
Authors: Schmult S. , Manfra M. J. , Sergent A. M. , Punnoose A. , Chou H. T. , Goldhaber‐Gordon D. , Molnar R. J.
Published: June 2006

High mobility two‐dimensional electron systems in GaN/AlGaN heterostructures have been realized by plasma assisted molecular beam epitaxy on GaN templates. In the density range of 1011 cm–2 to 1012 cm–2, mobility values exceeding 160000 cm2/Vs have been achieved. Scattering mechanisms that presently limit the production of higher mobility samples are discussed. We present results of a systematic study of the weak localization and antilocalization corrections to the classical conductivity at very low magnetic fields. The unambiguous observation of a conductivity maximum at B = 0 suggests that spin–orbit scattering is not negligible in GaN heterostructures as one might expect for a wide‐bandgap system. We have recently realized electron transport through GaN nanostructures. We report on the transport properties of the first quantum point contacts (QPCs) in GaN. These devices are used to study one‐dimensional transport in the Nitride system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A‐plane (11$ \bar 2 $0) InN growth on nitridated R‐plane (10$ \bar 1 $2) sapphire by ECR‐MBE
Authors: Kumagai Y. , Tsuyuguchi A. , Naoi H. , Araki T. , Na H. , Nanishi Y.
Published: June 2006

A‐plane (11$ \bar 2 $0) InN has been successfully grown on R‐plane (10$ \bar 1 $2) sapphire substrate by electron cyclotron resonance (ECR) plasma‐exited molecular beam epitaxy through substrate nitridation process. The substrate nitridation of R‐plane sapphire by ECR nitrogen plasma was carried out at 430 °C for 10 and 15 min. The results of reflection high‐energy electron diffraction (RHEED), X‐ray diffraction (XRD), and scanning electron microscopy indicated the formation of A‐plane InN on R‐plane sapphire. Inclusion of cubic InN was also observed together with A‐plane InN through RHEED and XRD measurements in case of A‐plane InN layer grown on 10 min nitridated substrate. However, when the nitridation time of R‐plane sapphire by ECR nitrogen plasma increased to 15 min, it is confirmed that formation of cubic InN was successfully suppressed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of single non‐polar GaN quantum dots
Authors: Rol F. , Gayral B. , Founta S. , Daudin B. , Eymery J. , Gérard J.‐M. , Mariette H. , Dang Le Si , Peyrade D.
Published: June 2006

We present a microphotoluminescence study of non polar GaN/AlN quantum dots (QDs) grown along the [11$ \bar 2 $0] axis. Despite the high QD density, single exciton lines could be isolated on the high energy side of the spectral distribution of the QD array emission. Linewidths down to 0.5 meV are reported, which is one order of magnitude lower than previously reported linewidths for polar GaN/AlN QDs. This difference is attributed to the drastic reduction of the internal field in non‐polar quantum dots. Temperature dependent measurements were performed up to 180 K. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Paramagnetic resonance of Shungite – a natural nano‐structured carbonaceous material
Authors: Yablokov M. Yu. , Augustyniak‐Jabłokow M. A. , Kempiński W. , Stankowski J. , Yablokov Yu. V.
Published: June 2006

Shungites Sh‐III and Sh‐IV (∼50% and 20% of carbon) have been studied by X‐band EPR method in the range 4.2–293 K. The week signal of Dyson shape (a /b = 2.25–2.40) observed from a bulk sample of Sh‐III has been observed to transform into an intensive Lorentzian line (ΔB = 1.99 mT, g = 2.0020) after sample grinding. The number of EPR responsible spins (2 × 1019 g–1) and the depth of penetration δ (∼60 µm) have been estimated. The shape of the signals (Dysonian or Lorentzian) is independent of T . ΔB and the g values decrease below 80 K to 1.15 mT and 2.0012. The signal intensity is independent of T down to 150 K. Isolated complexes of C60(C70)–n with K+(Na+) have been found in Sh‐IV. Analysis of the EPR spectra has been made taking into consideration the properties of the conductive materials such as metals and graphite. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Use of electrospray ionization mass spectrometry for the study of Ln(III) complexation and extraction speciation with calixarene‐CMPO in the fuel partitioning concept
Authors: Lamouroux C. , Rateau S. , Moulin C.
Published: June 2006

The calixarene‐bearing CMPO groups belong to a family of extracting agents recently developed for nuclear reprocessing. These molecules exhibit specific properties to separate actinides(III) from lanthanides(III) in nitric acid solution. Speciation of two distinct calixarene‐CMPO (carbamoyl phosphine oxide), substituted either in the wide rim or in the narrow rim with lanthanides (La, Eu, Yb), was undertaken. The complexation behaviour in single phase or in liquid‐liquid extraction was examined with two different electrospray spectrometer source geometries. The stoichiometries of the different complexes were reported and the selectivity of these calixarenes towards lanthanides was determined. The results obtained were concordant for the two spectrometers and confirm that electrospray mass spectrometry is a useful tool to study non‐covalently bonded complexes. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of calcium in complex samples using functional magnetic beads combined with electrodeless/sheathless electrospray ionization mass spectrometry
Authors: Wu Yi‐Ting , Chen Yu‐Chie
Published: June 2006

Conventionally, electrospray ionization ion trap mass spectrometry (ESI‐ITMS) is not used for the analysis of metal ions because metal ions may be of too low mass to be trapped by the mass analyzer. Furthermore, metal ions can easily precipitate during ESI processes because of their poor volatilities. We present an approach for solving these two problems using milk as the sample to demonstrate the feasibility of using ESI‐ITMS as the detection method for metal ions. Iron oxide magnetic beads with nitrilotriacetic acid (NTA) immobilized on their surface were used as affinity probes for calcium ions from dairy drinks. Ethylenediaminetetraacetic acid (EDTA) was used for the elution of the metal ions chelated by NTA on the beads. The EDTA eluent was analyzed by electrodeless/sheathless ESI‐ITMS. The use of functional magnetic beads to trap metal ions from complex samples can effectively reduce the interference from sample matrix. Using the EDTA eluent as the sample avoids the problem of the low volatility of metal ions during ESI‐ITMS analysis. This method gives measurements of calcium ions in dairy drinks quantitatively very close to the true values (<4% error). Copyright © 2006 John Wiley & Sons, Ltd.
The metabolism and excretion of 2‐methylaminoethoxycarbonyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylenedioxybiphenyl‐2′‐carboxylic acid (DDB‐S) in rats and human
Authors: Yoo Hye Hyun , Son Junghyun , Lee Jaeick , Kim Nam Sun , Shin Myungyoup , Kang Min‐Jung , Kim Dong‐Hyun
Published: June 2006

The metabolism and excretion of 2‐methylaminoethoxycarbonyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylenedioxybiphenyl‐2′‐carboxylic acid (DDB‐S) were investigated in both rats and humans using liquid chromatography/electrospray ion trap mass spectrometry (LC/ESI‐MS/MS). In rats, DDB‐S was rapidly eliminated from the body after a single 50 mg/kg intravenous injection, with urine being a major excretion route. DDB‐S was metabolically stable; approximately 96% of the administered dose was recovered in the form of the parent compound. Nevertheless, 12 metabolites were detected in the urine and feces collected from DDB‐S‐treated rats. The structural characterizations of the metabolites were elucidated from the MSn spectral analysis. Because DDB‐S has a pseudo‐symmetrical methylenedioxy biphenyl structure, regioselective deuterium‐substituted DDB‐S (d5‐DDB‐S) was used to assign the metabolic modification. The major metabolic pathways of DDB‐S were identified as demethylenation of the methylenedioxy moiety, O‐demethylation of the methoxy moiety and glucuronidation. In addition, N‐demethylation of the methylaminoethyl group was also detected as a minor reaction. Copyright © 2006 John Wiley & Sons, Ltd.
Bonding energetics in clusters formed by cesium salts: a study by collision‐induced dissociation and density functional theory
Authors: Maria Pierre‐Charles , Massi Lionel , Box Natzaret Sindreu , Gal Jean‐François , Burk Peeter , Tammiku‐Taul Jaana , Kutsar Martin
Published: June 2006

In relation to the interaction between 137Cs and soil organic matter, electrospray mass spectrometry experiments and density functional theory (DFT) calculations were carried out on the dissociation of positively charged adducts formed by cesium nitrate and cesium organic salts attached to a cesium cation [Cs(CsNO3)(CsA)]+ (A = benzoate, salicylate, hydrogen phthalate, hydrogen maleate, hydrogen fumarate, hydrogen oxalate, and hydrogen malonate ion). These mixed clusters were generated by electrospray from methanol solutions containing cesium nitrate and an organic acid. Collision‐induced dissociation of [Cs(CsNO3)(CsA)]+ in a quadrupole ion trap gave [Cs(CsNO3)]+ and [Cs(CsA)]+ as major product ions. Loss of HNO3 was observed, and also CO2 loss in the case of A = hydrogen malonate. Branching ratios for the dissociation into [Cs(CsNO3)]+ and [Cs(CsA)]+ were treated by the Cooks' kinetic method to obtain a quantitative order of bonding energetics (enthalpies and Gibbs free energies) between Cs+ and the molecular salt (ion pair) CsA, and were correlated with the corresponding values calculated using DFT. The kinetic method leads to relative scales of Cs+ affinities and basicities that are consistent with the DFT‐calculated values. This study brings new data on the strong interaction between the cesium cation and molecular salts CsA. Copyright © 2006 John Wiley & Sons, Ltd.
Electrospray ionisation tandem mass spectrometric investigation of phenylpropanoids and secoiridoids from solid olive residue
Authors: Innocenti Marzia , Marca Giancarlo la , Malvagia Sabrina , Giaccherini Catia , Vincieri Franco Francesco , Mulinacci Nadia
Published: June 2006

This work is focused on the recovery and structural characterisation of bioactive compounds from SOR (solid olive residue), a low cost and widely available by‐product in the Mediterranean basin. In the light of the interesting biological activities attributed both to secoiridoid and phenylpropanoids, the aim of this work was to carry out a systematic tandem mass spectrometric study for the identification and characterisation of these two class of compounds extracted from SOR derived from Coratina, a cultivar widely diffused in the south of Italy. Five phenylpropanoids, in addition to verbascoside, and two new secoiridoids were identified. Copyright © 2006 John Wiley & Sons, Ltd.
Monitored natural attenuation of chlorinated solvents—Moving beyond reductive dechlorination
Authors: Vangelas Karen M. , Looney Brian B. , Early Tom O. , Gilmore Tyler , Chapelle Francis H. , Adams Karen M. , Sink Claire H.
Published: June 2006

Monitored natural attenuation (MNA), while a remedy of choice for many sites, can be challenging when the contaminants are chlorinated solvents. Even with many high‐quality technical guidance references available, there continue to be challenges implementing MNA at some chlorinated solvent sites. The U.S. Department of Energy, as one organization facing such challenges, is leading a project that will incorporate developing concepts and tools into the existing toolbox for selecting and implementing MNA as a remediation option at sites with chlorinated solvent contamination. The structure and goals of this project were introduced in an article in the Winter 2004 issue of Remediation (Sink et al., 2004). This article is a summary of the three technical areas being developed through the project: mass balance, enhanced attenuation, and characterization and monitoring supporting the first two areas. These topics will be documented in separate reports available from the U.S. Department of Energy Office of Scientific and Technical Information at www.osti.gov. © 2006 Wiley Periodicals, Inc.
Ex situ treatment of MTBE‐containing groundwater by a UV peroxide system
Authors: Jamall Ijaz S. , Lu Tex T. X. , Powers James C.
Published: June 2006

This article describes the design, implementation, and operating results for an ex situ ultraviolet/hydrogen peroxide (UVP) system to treat methyl tert‐butyl ether (MTBE) in extracted groundwater. The UVP modification was designed to reduce the operation and maintenance costs of an existing groundwater pump‐and‐treat treatment system that relied on air stripping and carbon adsorption. The UVP system is relatively inexpensive and can easily be scaled to cope with different groundwater extraction rates up to 80 gpm by adding UV lamps in series or in parallel at the higher groundwater extraction rates. The MTBE concentration in the effluent from the UVP system to the carbon vessels decreased from an average of 590 μg/L to approximately 2 μg/L on average over 33 months of operation of the UVP. Incorporation of this UVP modification as a second‐stage treatment to the groundwater pump‐and‐treat/soil vapor extraction system, after the air stripper and prior to the carbon vessels, significantly increased the usable life of the carbon (from two months previously to about two years after installation) and completely resolved the issue of frequent MTBE breakthroughs of the carbon that had plagued the remediation system since its inception. © 2006 Wiley Periodicals, Inc.
Charakterisierung von Plasmapolymeren mittels Thermolumineszenzmessungen
Authors: Krüger S. , Schulze R.‐D. , Brademann‐Jock K. , Swaraj S. , Friedrich J.
Published: June 2006

Dünne, mit einem gepulsten Plasma hergestellte Polymerschichten wurden untersucht. Diese Plasmapolymere sollten eine chemisch besser definierte Struktur haben, weil der Anteil an rein chemisch polymerisiertem Produkt während der Plasma‐aus‐Zeit steigen sollte, während der Anteil an Schichtbildung, der innerhalb der kurzen Plasmapulse durch Monomerfragmentierung und statistische Polyrekombination erzeugt wird, zurückgedrängt wird. Der Monomerfragmentierungsprozeß ist im kontinuierlich brennenden Plasma (cw‐Mode) demgegenüber der Hauptprozeß. Neben der Anwendung der klassischen Element‐ und Bindungsanalysentechnik XPS (X‐ray Photoelectron Spectroscopy) wurden hier die Schichten auch mittels Thermolumineszenz untersucht. Defekte und Strukturanomalitäten in Polymeren sollten mit dieser Methode charakterisiert werden können. Untersuchungsobjekte waren funktionalgruppentragende Plasmapolymerschichten, die biosensorische oder biokompatible Funktionen besitzen oder als Haftvermittler in Metall‐Polymercompositen eingesetzt werden.
Plasmapolymerschichten als Basis für maßgeschneiderte funktionale Oberflächen
Authors: Prucker Oswald , Stöhr Torsten , Rühe Jürgen
Published: June 2006

Das Maßschneidern von Oberflächeneigenschaften mit Hilfe dünner Polymerschichten ist Gegenstand vieler aktueller Forschungsarbeiten auf verschiedenen Gebieten der Mikrosystemtechnik oder auch der Bioanalytik. Eine exakte Einstellung von Oberflächeneigenschaften gelingt aber nur über chemisch wohldefinierte Prozesse, die in der Regel reaktive Gruppen an Oberflächen für die Anbindung von Molekülen voraussetzen. In diesem Beitrag fassen wir Arbeiten zusammen, bei denen inerte Oberflächen mit chemisch definierten, kovalent gebundenen Polymerschichten modifiziert wurden, in dem zunächst aminogruppenhaltige Plasmapolymerschichten auf den Oberflächen der zu beschichtenden Substrate abgeschieden wurden. An die Aminogruppen wurden dann Initiatormoleküle angeknüpft, von denen aus Polymerschichten durch oberflächeninitiierte Polymerisation generiert wurden. Durch Variation der dafür eingesetzten Monomeren können so Oberflächenschichten mit sehr verschiedenen Eigenschaften erzeugt werden.
The impact of habitat fragmentation on genetic structure of the Japanese sika deer (Cervus nippon) in southern Kantoh, revealed by mitochondrial D‐loop sequences
Authors: Yuasa T. , Nagata J. , Hamasaki S. , Tsuruga H. , Furubayashi K.
Published: June 2006

In southern Kantoh, Japanese sika deer (Cervus nippon) are distributed discontinuously due to large urban areas and developed road networks. To assess the impact of habitat fragmentation on sika deer subpopulations, we examined mitochondrial D‐loop sequences from 435 individuals throughout southern Kantoh. About 13 haplotypes were detected, and their distributions revealed spatial genetic structure. Significant genetic differentiation was observed among seven of eight subpopulations. We found no significant correlation between pairwise FST and geographical distance among subpopulations. Genetic diversity indices suggested that seven of eight subpopulations had probably experienced population bottlenecks in the recent past. Therefore, and in the light of the results of a nested clade analysis of these haplotypes, we conclude that recent fluctuations in population size and the interruption of gene flow due to past and present habitat fragmentation have played major roles influencing the spatial genetic structure of the sika deer population. This is the first evidence of spatial genetic population structure in the highly fragmented sika deer population in Honshu, Japan.
Nonparametric Estimation of Item and Respondent Locations from Unfolding-type Items
Authors: Johnson Matthew S.
Published: June 2006

Unlike their monotone counterparts, nonparametric unfolding response models, which assume the item response function is unimodal, have seen little attention in the psychometric literature. This paper studies the nonparametric behavior of unfolding models by building on the work of Post (1992). The paper provides rigorous justification for a class of nonparametric estimators of respondents’ latent attitudes by proving that the estimators consistently rank order the respondents. The paper also suggests an algorithm for the rank ordering of items along the attitudes scale. Finally, the methods are evaluated using simulated data.
Long-term predictors of outcome in fatigued employees on sick leave: a 4-year follow-up study
Authors: LEONE STEPHANIE S. , HUIBERS MARCUS J. H. , KANT IJMERT , VAN SCHAYCK CONSTANT P. , BLEIJENBERG GIJS , ANDRÉ KNOTTNERUS J.
Published: June 2006

Background. Persistent fatigue is strongly associated with functional status and can lead to absenteeism and work disability. Despite several prognostic studies on chronic fatigue, little attention has been paid to occupational outcomes.

Method. A total of 127 fatigued employees on sick leave were followed-up after 4 years to determine long-term predictors of work disability, fatigue caseness and chronic fatigue syndrome (CFS)-like caseness. Measures included fatigue, physical functioning, illness attributions, psychological problems and emotional exhaustion.

Results. Thirty-three participants (26%) were receiving work disability benefits at the 4-year follow-up. Older age and lower levels of physical functioning predicted work disability. Weaker psychological attributions and lower levels of physical functioning were predictors of fatigue caseness. CFS-like caseness was predicted by female gender and lower levels of physical functioning. Self-reported physical functioning remained a strong and statistically significant determinant of work disability [odds ratio (OR) 0·45, 95% confidence interval (CI) 0·24–0·87] and CFS-like caseness (OR 0·20, 95% CI 0·09–0·43) after controlling for confounders.

Conclusions. This study suggests that physical functioning plays an important role in the persistence of fatigue complaints and work disability in employees on sick leave. The course of fatigue is a complex process, and exploring temporal relationships between fatigue, functional status and work status in future research could provide valuable information for the improvement of fatigue management.
A community of grace: the social and theological world of the Puṣṭi Mārga vārtā literature
Authors: SAHA SHANDIP
Published: June 2006

In the history of Hindi literature, the oldest extant text of medieval Hindi prose is the collection of hagiography known as the as the vārtā literature which, since the seventeenth century, has been central to the religious life of the Hindu devotional community known as the Puṣṭi Mārga. This article argues that a close examination of these texts in their proper social and historical context reveals that the vārtā literature was written and revised during a time when the Puṣṭi Mārga was slowly expanding its sphere of religious influence in Western and Central India. The result was a body of literature whose principal purpose was to shape the religious self-identity of the Puṣṭi Mārga by stressing the community as a close-knit and exclusive fellowship of believers who owed their final allegiance to Kṛṣṇna and the community's religious leaders who were known as mahārājas.
A Daoist princess and a Buddhist temple: a new theory on the causes of the canon-delivering mission originally proposed by princess Jinxian (689–732) in 730
Authors: CHEN JINHUA
Published: June 2006

Yunjusi has, over the past few decades, earned a worldwide reputation for the immense repository of Buddhist scriptures carved on the stone slabs that are stored there (the so-called Stone Canon of Fangshan [Fangshan shijing]). The heroic enterprise of carving the whole Buddhist canon into stone had already been initiated during the Daye era (604–617) thanks to the resolve of the monk Jingwan (?–639) and support from Empress Xiao (d. after 630) of Sui Yangdi (r. 604–617) and her brother Xiao Yu (574–647). However, it did not accelerate until 740 when Xuanzong, as urged by his sister Princess Jinxian (689–732), ordered two eminent monks from the capital monastery Great Chongfusi (one of them being the great Buddhist historian and cataloguer Zhisheng [fl. 740s]) to deliver over four-thousand fascicles of Buddhist translations, which constituted the main body of the newly compiled Kaiyuan Buddhist canon, to Yunjusi to serve as base texts for the stone scriptures. This event is remarkable and puzzling for at least three reasons. First, although Yunjusi, a local temple situated far from the capitals, was not a Kaiyuan monastery, it still had the honour of being chosen as a recipient of the Kaiyuan canon. Second, one cannot help but wonder why and how two Chongfusi monks, who were of obvious prestige, should have demonstrated such enthusiasm in escorting so many Buddhist texts to this apparently marginal temple. Finally, it is difficult to understand why Princess Jinxian, who was then an ordained Taoist nun, played such an active and decisive role in this project. Such a remarkable and important event inevitably invited considerable attention from scholars, who have noted, and attempted to explain, several aspects of the mystery surrounding Princess Jinxian's Yunjusi ties. This article attempts to address this old issue from a perspective that has never been explored. It broaches and elaborates on the possibility that the great AvatamD saka master Fazang's (643–712) possible ties with Yunjusi form a major missing piece in this complex puzzle.