bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiofrequency heating at 9.4T: In vivo temperature measurement results in swine
Authors: Shrivastava Devashish , Hanson Timothy , Schlentz Robert , Gallaghar William , Snyder Carl , DelaBarre Lance , Prakash Surya , Iaizzo Paul , Vaughan J. Thomas
Published: October 2007

In vivo temperatures were correlated to the whole head average specific absorption rate (SARavg) at 9.4T using 12 anesthetized swine (mean animal weight = 52 kg, standard deviation = 6.7 kg). Correlating the temperatures and SARavg is necessary to ensure safe levels of human heating during ultra‐high field MR exams. The temperatures were measured at three depths inside the brain, in the rectum, and at the head‐skin of swine. A 400 MHz, continuous wave RF power was deposited to the head using a volume coil. The SARavg values were varied between 2.7–5.8 W/kg. The RF power exposure durations were varied between 1.4–3.7 hr. To differentiate the temperature response caused by the RF from that of the anesthesia, the temperatures were recorded in four unheated swine. To study the effect of the spatial distribution of the RF and tissue properties, the temperature probes were placed at two brain locations (n = 4 swine for each location). Results showed that the in vivo brain temperatures correlated to the SARavg in a geometry‐dependent manner. Additionally, 1) the skin temperature change was not the maximum temperature change; 2) the RF heating caused an inhomogeneous brain temperature distribution; and 3) the maximum temperature occurred inside the brain. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Accelerated short‐TE 3D proton echo‐planar spectroscopic imaging using 2D‐SENSE with a 32‐channel array coil
Authors: Otazo Ricardo , Tsai Shang‐Yueh , Lin Fa‐Hsuan , Posse Stefan
Published: October 2007

MR spectroscopic imaging (MRSI) with whole brain coverage in clinically feasible acquisition times still remains a major challenge. A combination of MRSI with parallel imaging has shown promise to reduce the long encoding times and 2D acceleration with a large array coil is expected to provide high acceleration capability. In this work a very high‐speed method for 3D‐MRSI based on the combination of proton echo planar spectroscopic imaging (PEPSI) with regularized 2D‐SENSE reconstruction is developed. Regularization was performed by constraining the singular value decomposition of the encoding matrix to reduce the effect of low‐value and overlapped coil sensitivities. The effects of spectral heterogeneity and discontinuities in coil sensitivity across the spectroscopic voxels were minimized by unaliasing the point spread function. As a result the contamination from extracranial lipids was reduced 1.6‐fold on average compared to standard SENSE. We show that the acquisition of short‐TE (15 ms) 3D‐PEPSI at 3 T with a 32 × 32 × 8 spatial matrix using a 32‐channel array coil can be accelerated 8‐fold (R = 4 × 2) along y‐z to achieve a minimum acquisition time of 1 min. Maps of the concentrations of N‐acetyl‐aspartate, creatine, choline, and glutamate were obtained with moderate reduction in spatial‐spectral quality. The short acquisition time makes the method suitable for volumetric metabolite mapping in clinical studies. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
MRI of regular‐shaped cell‐encapsulating polyhedral microcontainers
Authors: Gimi Barjor , Artemov Dmitri , Leong Timothy , Gracias David H. , Bhujwalla Zaver M.
Published: October 2007

We devised cubic and pyramidal microcontainers for cell encapsulation. While the cube is easier to manipulate, the pyramid offers a higher surface area‐to‐volume ratio and may therefore provide the encapsulated cells with increased access to nutrients. To discern the microcontainers' implant location and environment, and to aid in image‐guided therapy, we showed noninvasive detection of microcontainers using MRI. Diamagnetic microcontainers were imaged using the radio frequency (RF) shielding effect, with negative contrast localized to the interior of the microcontainers. For applications in which it is difficult to distinguish the microcontainers from other hypointensities, positive contrast can be used to discern them. We showed positive‐contrast MRI of a diamagnetic microcontainer. To image microcontainers that are smaller than the spatial resolution of MRI, we performed in vivo negative‐contrast MRI of a ferromagnetic microcontainer. As opposed to the diamagnetic microcontainer, the ferromagnetic microcontainer created a region of MRI contrast several times larger than the microcontainer's dimensions. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Forecasting vertical ground surface movement from shrinking/swelling soils with artificial neural networks
Authors: Doris Jeffrey J. , Rizzo Donna M. , Dewoolkar Mandar M.
Published: October 2007

Artificial neural networks (ANNs) are used to estimate vertical ground surface movement when soils expand and contract due to changes in soil moisture content caused by changing climate conditions. Several counterpropagation ANN test cases were investigated to map climate data (i.e. temperature and rainfall) to vertical ground surface movement at field sites in Texas and Australia. Three of the four ANN test cases use a historical time series of climate data to forecast ground surface elevation relative to a specified datum. The fourth ANN test case predicts the rate of ground surface movement, and requires post‐processing of the predicted rates to calculate ground surface elevation relative to a specified datum. The counterpropagation network has demonstrated a successful mapping of temperature and rainfall data to vertical ground surface movement at a field site when it is trained with a subset of data from the same field site (test cases 1 and 2). The results of training an ANN on one field site and testing it on another field site (test cases 3 and 4) demonstrate the ability of the ANN to capture trends in vertical ground surface movement. When compared with the predictions from a physics‐based method (shrink test‐water content method) that requires measurements/estimates of changes in soil water content, the ANN‐based predictions (based on climatic changes) captured the trends in the field measurements of shrinking–swelling soil surface movements equally well. These findings are promising and merit further investigation with data from additional field sites. Copyright © 2007 John Wiley & Sons, Ltd.
Ionic liquids as catalytic additives for the acceleration of the photopolymerization of poly(ethylene glycol dimethacrylate)s
Authors: Chesnokov Sergey A , Zakharina Marya Yu , Shaplov Alexander S , Chechet Yuriy V , Lozinskaya Elena I , Mel'nik Olga A , Vygodskii Yakov S , Abakumov Gleb A
Published: October 2007

BACKGROUND: The fast development of practical applications of photopolymerizable compositions (PPCs) leads to a growing demand for the elaboration of novel monomers and simultaneously for the investigation of three‐dimensional polymerization mechanisms including the possible influence of initiator, additives, etc. The aim of the current study is to explore and clarify the role of ionic liquids (ILs) as environmentally friendly catalytic additives in the photopolymerization of poly(ethylene glycol dimethacrylate)s.

RESULTS: The photopolymerization of triethylene glycol dimethacrylate (TEGDM) and poly(ethylene glycol‐400 dimethacrylate) (PEGDM) in the presence of various ILs both imidazolium‐based, i.e. [1‐methyl‐3‐alkylim]+ (CF3SO2)2N− (im = imidazolium; alkyl = C2H5, C4H9, C14H29), and phosphonium‐based, i.e. [P+ (C6H13)3(C14H29)]X− (X− = PF6−, BF4−, (CF3SO2)2N−, Cl−), as catalytic additives was investigated. The influence of the concentration of the ionic salts as well as the nature of the ILs upon the photopolymerization was studied in detail. It was found that imidazolium ILs accelerate TEGDM photopolymerization and suppress the polymerization of PEGDM. In contrast, polymerization of PEGDM with extra small amounts of phosphonium ionic solvents proceeded at a high rate and offered access to new polymers and the utilization of low‐reactivity monomers in PPCs.

CONCLUSION: The most striking advantage is that the use of certain ILs permits the control of polymerization rate to achieve maximum oligomer conversion. Copyright © 2007 Society of Chemical Industry
Learning the drug target‐likeness of a protein
Authors: Xu Huan , Xu HangYang , Lin MingZhi , Wang Wei , Li ZiMu , Huang JiaJu , Chen YuZong , Chen Xin
Published: October 2007

Current drug discovery and development approaches rely extensively on the identification and validation of appropriate targets; for example, those with marketable and robust therapeutics. Wide‐ranging efforts have been directed at this problem and various approaches have been developed to identify disease‐associated genes as candidates. In this work, we show with statistical significance that successful drug targets, in addition to their linkage to disease, share common characteristics that are disease‐independent. For example, marked differences in functional category, tissue specificity, and sequence variability are observed between known targets and average proteins. These results lead to an interesting hypothesis: potentially good drug targets shall have some desired properties, which we refer to as “drug target‐likeness” that are beyond their disease‐associations. Because of the limited availability of comprehensive protein characteristics data, we tried to learn the drug target‐likeness property at the sequence level. Results show that a support vector machine model is able to accurately distinguish targets from nontargets entirely with sequence features. It is our hope that these encouraging results will invite future systematic proteomic scale experiments to gather necessary protein characteristics data for the accurate and predictive definition of “drug target‐likeness”, providing a new perspective toward understanding and pursuing effective therapeutics.
Proteomic analysis of proteins from bronchoalveolar lavage fluid reveals the action mechanism of ultrafine carbon black‐induced lung injury in mice
Authors: Chang Chih‐Ching , Chen Shu‐Hui , Ho Shih‐Hsin , Yang Chun‐Yuh , Wang Hong‐Da , Tsai Mei‐Ling
Published: October 2007

Previous studies have shown that ultrafine carbon black (ufCB) could cause oxidative stress and lung injury, but the mechanisms have not been clearly demonstrated. In this study, 1‐D gel electrophoresis coupled with LC/MS/MS (1‐D geLC/MS/MS) was carried out with bronchoalveolar lavage fluid (BALF) to identify proteins associated with ufCB‐induced lung injury. If required, Western blot was conducted additionally to validate proteins. Thirty‐three proteins were identified, including leukemia inhibitory factor receptor (LIFR) and epidermal growth factor receptor (EGFR). Western blot analysis showed that ufCB exposure caused the increases of LIFR and EGFR in BALF and decreases of both receptors in lung tissues, suggesting the acceleration of epithelial shedding from the lung and increase of cell debris with membrane proteins EGFR and LIFR in BALF. There were strong correlations between vascular endothelial growth factor (VEGF) and albumin (p<0.01) or α2‐macroglobulin (α2M) in BALF (p<0.05). Importantly, antioxidant ceruloplasmin (Cp) was shown to be produced from lung epithelial cells in response to ufCB exposure. This is the first study to apply 1‐D ge LC/MS/MS and experimental studies to reveal the mechanisms involved in the pathogenesis of ufCB‐induced lung injury.
Atopic characteristics of wheezing children and responses to prednisolone
Authors: Jartti Tuomas , Lehtinen Pasi , Vanto Timo , Vuorinen Tytti , Hiekkanen Heikki , Hartiala Jaakko , Mäkelä Mika J , Ruuskanen Olli
Published: October 2007

We wanted to test the hypothesis that the efficacy of systemic corticosteroid is associated with atopic characteristics in wheezing children.

A randomized controlled trial comparing oral prednisolone (2 mg/kg/day in 3 divided doses for 3 days) with placebo in hospitalized wheezing children (n = 266, median 1.6 years, range 3 months to 15.2 years) was conducted. In this post‐hoc analysis, we assessed the link between the efficacy of prednisolone and several atopic characteristics, such as atopy, aeroallergen sensitization, total IgE level, number of sensitizations, eczema, atopic eczema, blood or nasal eosinophils, exhaled nitric oxide, positive modified asthma predictive index/asthma, inhaled corticosteroid medication and parental asthma/allergy. Virology was studied comprehensively. Our primary endpoint was the time until ready for discharge, and the most important secondary endpoint was the occurrence of relapses during the following 2 months. For statistics, we used interaction analyses in uni‐ and multivariate regression models.

Overall, prednisolone did not decrease any of our predefined clinical endpoints. Neither was the efficacy of prednisolone associated with atopy. However, prednisolone significantly decreased the time until ready for discharge in children with positive modified asthma predictive index/asthma, inhaled corticosteroids, or rhinovirus infection and/or in children without azithromycin treatment. Prednisolone significantly decreased relapses in children with eczema, nasal eosinophilia and rhinovirus infection.

The multiple clinical, inflammatory and viral markers associating with the efficacy of prednisolone should be confirmed in prospective trials. It is important that corticosteroid intervention trials have strict design for these potentially confounding factors. Pediatr Pulmonol. 2007; 42:1125–1133. © 2007 Wiley‐Liss, Inc.
Spirometry in 5‐year‐olds—validation of current guidelines and the relation with asthma
Authors: Turner Stephen W. , Craig Leone C.A. , Harbour Paul J. , Forbes Sarah H. , McNeill Geraldine , Seaton Anthony , Devereux Graham , Helms Peter J.
Published: October 2007

Introduction. Spirometry is more frequently measured in younger children. Our primary aim was to validate 2005 ATS‐ERS Task Force standards for spirometry in adults and older children among a population of 5‐year‐old children. Our secondary aim was to relate spirometry to asthma symptoms.

Methods

Children were participants in a longitudinal cohort study where asthma symptoms and spirometry were assessed.

Results

Of the 827 children assessed, spirometry was obtained in 638 (85 with wheeze). A back‐extrapolated volume/FVC ratio of <5% was achieved in 99% of children, the best two FVC were ≤150 ml of each other in 89% and three efforts were obtained within six attempts in 88%. The best two FVC were within 10% of each other in 82% of children. Only 13% achieved a forced expiratory time (FET) of ≥3 sec, whereas 80% had an FET of ≥1 sec. All criteria (including FET ≥1 s and FVC ≤10%) were met in 400 (65%) of the 638 children. Most spirometric indices were reduced in association with current wheeze and a history of asthma; children with current wheeze had a mean reduction of 0.65 FEV1 z score compared to healthy children, P < 0.001. An FEV1 z score of −1.0 had 82% sensitivity but only 50% specificity for current wheeze, the corresponding numbers for an FEF50 z score of −1.0 being 79% and 71%.

Conclusions

The standards for spirometry are mostly achieved in this age group but are not necessarily valid and require revision. Reliable spirometry is feasible in 5‐year‐old children where reduced measurements are associated with asthma symptoms and in whom FEF50 appears to be the most discriminatory variable. Pediatr Pulmonol. 2007; 42:1144–1151. © 2007 Wiley‐Liss, Inc.
Longitudinal monitoring of pediatric cystic fibrosis lung disease using nitrite in exhaled breath condensate
Authors: Horak F. , Moeller A. , Singer F. , Straub D. , Höller B. , Helbich T.H. , Schneider B. , Eichler I. , Wildhaber J.H. , Hall G.L.
Published: October 2007

Cystic fibrosis (CF) lung disease is characterized by airway inflammation and airway infection. Nitrites in exhaled breath condensate (EBC‐NO) have been shown to be increased in children and adults with CF compared to healthy controls suggesting its use as a measure of airway inflammation. This longitudinal study aimed to evaluate if repeated measurements of EBC‐NO are helpful in monitoring CF lung disease activity in children. Thirty‐two children with mild CF lung disease (age 10.6 ± 3.3 years) were recruited in two study centers. Follow‐up visits occurred every 3 months over a period of 1 year with a total of five visits. Each visit included a clinical assessment incorporating a modified Shwachman–Kulczycki (SK) score, spirometry, an oropharyngeal swab, or sputum sample for bacterial analysis and an EBC sample analyzed for NO using a spectrophotometric assay. Furthermore at the first and the last visit a chest radiograph was done and scored (Chrispin–Norman (CN) score). There was no correlation of EBC‐NO and parameters of spirometry, SK‐score, or CN‐score. Furthermore, increased EBC‐NO levels did not predict subsequent pulmonary exacerbations. We conclude that repeated measurements of EBC‐NO are not helpful in the longitudinal monitoring of mild CF lung disease in children. Pediatr Pulmonol. 2007; 42:1198–1206. © 2007 Wiley‐Liss, Inc.
Lung disease in niemann–pick disease
Authors: Guillemot Nathalie , Troadec Corinne , de Villemeur Thierry Billette , Clément Annick , Fauroux Brigitte
Published: October 2007

Background

Lung involvement in children with Niemann–Pick disease has rarely been studied systematically.

Objective

To assess the involvement of the lung and the value of bronchoalveolar lavage in children with Niemann–Pick diseases.

Design

Retrospective analysis of patient records.

Patients

Thirteen patients, with type A (n = 1), type B (n = 10), and type C (n = 2) Niemann–Pick disease, aged 2 months to 9 years at diagnosis, were included in the study.

Interventions

Lung involvement was assessed by clinical evaluation, chest radiograph, lung computed tomography (CT) scan, pulmonary function tests, and bronchoalveolar lavage fluid analysis.

Results

Respiratory symptoms were present at diagnosis in 10 patients and developed during follow up in the three other patients. All patients showed signs of interstitial lung disease on chest X‐ray and lung CT scan. Bronchoalveolar lavage fluid analysis (n = 7) revealed a marked accumulation of foamy macrophages (Niemann–Pick cells) in all patients. At follow up, one patient died of respiratory failure, five patients required long term oxygen therapy and seven other patients presented a chronic obstructive pulmonary disease (n = 6) or chronic cough (n = 1).

Conclusion

Lung disease was observed in all the patients included in the present study. Bronchoalveolar lavage may be useful in Niemann–Pick diseases by showing the presence of characteristic Niemann–Pick cells. Pediatr Pulmonol. 2007;42:1207–1214. © 2007 Wiley‐Liss, Inc.
Functional 3D photonic films from polymer beads
Authors: Lange Birger , Fleischhaker Friederike , Zentel Rudolf
Published: October 2007

This paper describes synthesis and properties of polymer opals with a special emphasis on functional opals. Polymer opals are formed from monodisperse polymer colloids by self‐assembly. Their potential applications range from coloring pigments, 3D bicontinuous supports for catalysis to photonic materials. This latter application requires especially the controlled creation of defects and the incorporation of fluorescent materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic analysis of the optical and electronic properties of semiconductor photonic‐crystal structures
Authors: Pasenow Bernhard , Reichelt Matthias , Stroucken Tineke , Meier Torsten , Koch Stephan W.
Published: October 2007

The combination of dielectric photonic crystals and semiconductor nanostructures makes it possible to design many important aspects of the optoelectronic system response. A spatially‐varying dielectric environment induces modifications of the transversal and the longitudinal components of the electromagnetic field which have to be included in the self‐consistent microscopic analysis of the optical properties of hybrid semiconductor photonic‐crystal structures. In this paper, the development of a semiclassical microscopic theory is reviewed. Whereas the classical electromagnetic field is described at the level of Maxwell's equations, a full many‐body quantum theory is used for the interacting electronic excitations in the semiconductor material. Relevant examples of the numerical solutions of the resulting Maxwell semiconductor Bloch equations are presented showing, e.g., characteristic modifications of excitonic absorption spectra, the spatio‐temporal dynamics of electronic wave packets, as well as an increase of the optical gain in properly designed device geometries. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tuneable photonic crystals obtained by liquid crystal infiltration
Authors: Kitzerow H.‐S. , Lorenz A. , Matthias H.
Published: October 2007

The unique combination of fluidity and birefringence that is characteristic for liquid crystals is quite suitable in order to tune the optical properties of photonic crystals. Here, some experimental examples are reviewed where colloidal crystals (artificial opals and inverse opals), two‐ and three‐dimensional photonic crystals made of macroporous silicon and photonic crystal fibres have been filled with liquid crystals and the changes of their optical properties due to temperature variation or external fields have been investigated. The performance and limits of state‐of‐the‐art photonic crystals filled with liquid crystals are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ultra‐low refractive index mesoporous substrates for waveguide structures
Authors: Konjhodzic D. , Schröter S. , Marlow F.
Published: October 2007

Mesoporous silica films were synthesized by dip‐coating. In this process, evaporation induced self‐assembly leads to the formation of an ordered pore structure. Two types of films with different optical properties have been found in dependence on the humidity during the synthesis. The synthesis field has been explored in order to locate optically perfect films. Both film types, denoted as A and B, have been characterized by small angle X‐ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). From these results, the different structures for the two film types have been determined. A‐type films have a stable worm‐like structure, whereas for B‐type films a sustained lamellar structure has been found. A very low refractive index has been measured for A‐type films and its stability has been examined. These films have been used as low‐n supports to realize waveguide structures based on polymers, Ta2O5, and the ferroelectric material PZT. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solitary wave formation in one‐dimensional photonic crystals
Authors: Essig Sabine , Niegemann Jens , Tkeshelashvili Lasha , Busch Kurt
Published: October 2007

We present a variational approach to the problem of solitary wave formation in one‐dimensional nonlinear photonic crystals. In particular, we analyze how an arbitrary initial pulse is reshaped into a stable solitary wave by shedding excess radiation. Owing to the strong Bragg‐scattering near photonic band edges this reshaping results in non‐trivial dynamics and we show that within the variational framework we can quantitatively describe this complex wave dynamics for relatively short times. For longer times, the results become less accurate but still allow a qualitatively correct description. Finally, we discuss how an improved handling of the coupling to radiation modes can lead to an accurate description of the long‐term behavior. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bloch modes and group velocity delay in coupled resonator chains
Authors: Möller Björn M. , Artemyev Mikhail V. , Woggon Ulrike
Published: October 2007

Coherently coupled optical microresonators are studied as a concept for guiding and slowing down light. So‐called coupled‐resonator optical waveguides (CROWs) composed of nanocrystal doped microspheres are studied using mode mapping spectroscopy at the diffraction limit and microphotoluminescence spectroscopy. We demonstate coherent photon coupling in one‐dimensional multiresonator chains and show the evolution of individual cavity modes into waveguide modes. A coupled‐oscillator model is developed, which explains the resulting coupled‐resonator mode patterns in finite systems. The potential to slow down the group velocity of light by orders of magnitude is explored. Experimentally, a slowing‐factor S = 31 has been observed. A model for disorder in CROW structures is developed, by which size tuning of individual resonators is found to result in anticrossing relations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear and nonlinear effects of light propagation in low‐index photonic crystal slabs
Authors: Iliew R. , Etrich C. , Augustin M. , Kley E.‐B. , Nolte S. , Tünnermann A. , Lederer F.
Published: October 2007

We investigate theoretically and experimentally photonic crystals realised in slab waveguides made of materials with a low refractive index. Although in such systems a two‐dimensional photonic bandgap for TE polarised light can be achieved, the low index imposes several restrictions influencing the performance. We investigate the transmission and dispersion properties of photonic crystal defect waveguides, high‐quality factor microcavities and unusual phenomena of light propagation and localisation in truly periodic systems without defects. This is compared to results obtained in high‐index materials. Furthermore we investigate theoretically frequency conversion and solitons in nonlinear photonic crystals. An optical parametric oscillator in a photonic crystal microcavity and strongly localised solitons in coupled microcavities are proposed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite element simulation of radiation losses in photonic crystal fibers
Authors: Pomplun Jan , Zschiedrich Lin , Klose Roland , Schmidt Frank , Burger Sven
Published: October 2007

In our work we focus on the accurate computation of light propagation in finite size photonic crystal structures with the finite element method (FEM). We discuss how we utilize numerical concepts like high‐order finite elements, transparent boundary conditions and goal‐oriented error estimators for adaptive grid refinement in order to compute radiation leakage in photonic crystal fibers and waveguides. Due to the fast convergence of our method we can use it e.g. to optimize the design of photonic crystal structures with respect to geometrical parameters, to minimize radiation losses and to compute attenutation spectra for different geometries. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear and non‐linear optical experiments based on macroporous silicon photonic crystals
Authors: Wehrspohn Ralf B. , Schweizer Stefan L. , Sandoghdar Vahid
Published: October 2007

Macroporous silicon is a model system for 2D silicon photonic crystals. In this review, we describe our recent theoretical and experimental advances in the macroporous silicon technology as well as in novel near‐field optical experiments concerning modified light emission from photonic crystal cavities and waveguides. We also review our recent work on tuning silicon photonic crystals by free‐carriers or non‐linear effects and compare the two tuning mechanisms. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dispersive properties of photonic crystal waveguide resonators
Authors: Sünner T. , Gellner M. , Scholz M. , Löffler A. , Kamp M. , Forchel A.
Published: October 2007

We have investigated the group delay and the dispersion of light propagating through photonic crystal (PhC) resonators defined in 240 nm thick GaAs membranes. The design of the resonators is based on a PhC heterostructure, which combines waveguide sections with different lattice constants along a PhC waveguide. The measurements were performed by detecting the phase shift of a microwave signal which was modulated onto the light of a tunable laser source. The group delay was found to increase linearly with the quality factor of the resonator, in good agreement with the prediction of a model where the PhC resonator is replaced by an equivalent Fabry–Perot resonator. An alternative analysis of the measurements was performed using a Hilbert transform approach. A maximum group delay of 132 ps was observed for a resonator with a quality factor of 82000. The overall length of this resonator was 10.4 μm, resulting in a propagation speed of 7.88 × 104 m/s (c/3800). The maximum dispersion of the resonator was around 1.7 ns/nm, which is equivalent to 100 km of standard optical fiber. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Negative refraction in 2D photonic crystal super‐lattice: towards devices in the IR and visible ranges
Authors: Neve‐Oz Y. , Golosovsky M. , Frenkel A. , Davidov D.
Published: October 2007

We consider a planar structure consisting of the periodic array of dielectric rods of two different diameters whereas d1/d2 = 2. The rods have the same dielectric constant ε = 4. Such array exhibits structural modulation and forms a two‐dimensional photonic superlattice. This results in a narrow transmission subband (the bandwidth is 15% of the total stopband width) inside the photonic stop‐band. For the frequencies corresponding to this subband we find high transmittivity accompanied by negative refraction. Although we perform our computer simulations for the microwave range, the small dielectric constant of the rods and small insertion loss for the frequencies in the transmission band suggests that scaling to the optical range using similar structures is possible. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photonic crystals based on chiral liquid crystal
Authors: Ozaki M. , Matsuhisa Y. , Yoshida H. , Ozaki R. , Fujii A.
Published: October 2007

Liquid crystals including chiral molecule have a self‐organized helical structure with nano‐scaled periodicity, which can be regarded as a one‐dimensional (1D) photonic crystal. We have so far investigated lasing characteristics at an edge of the 1D photonic band gap (PBG) of dye‐doped chiral liquid crystals such as cholesteric liquid crystal (CLC) and ferroelectric liquid crystal (FLC). A band‐edge excitation effect on the CLC lasing has been experimentally demonstrated by matching the excitation laser wavelength to the higher energy‐edge of the PBG of a dye‐doped CLC. The wavelength tuning of the laser action upon changing electric field strength has been achieved in FLC. We have proposed the defect modes characteristic to the helicoidal structure of the chiral liquid crystal and demonstrated the lasing from the chiral defect modes. A twist defect mode in a transmission spectrum of the composite film consisting of two photopolymerized CLC layers has been experimentally demonstrated. A new type of defect mode in a chiral liquid crystal on the basis of the local deformation of the 1D periodic helical structure has also been proposed, and the possibility of the wavelength tuning has been demonstrated in this system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanophotonic Materials: Photonic Crystals, Plasmonics and Metamaterials
Authors: Wehrspohn Ralf B. , Kitzerow Heinz‐Siegfried , Busch Kurt
Published: October 2007

Following the successful launch of the book on 'Photonic Crystals' in 2004 [1], this special issue of physica status solidi again comprises the work of research groups from the corresponding Priority Programme of the German Research Foundation and some of their close collaborators. Three years on, the understanding of photonic crystal properties has improved across numerous materials systems, applications were devised and developed approaching the industrial stage, and attention extended to the new areas of plasmonic crystals and metamaterials. The current issue presents a collection of Feature Articles reporting on the progress in this active field.

In the tradition of the first publication, the Cover Picture shows an overlay of a 3D photonic crystal made from macroporous silicon, a simulation of a waveguide splitter, and the lasing modes of a planar photonic crystals laser made from III–V‐compound semiconductors (Picture courtesy of conImago, http://www.conimago.de). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First principles study of structural and electronic properties of Bex Zn1–xS and Bex Zn1–xTe alloys
Authors: Ameri M. , Rached D. , Rabah M. , El Haj Hassan F. , Khenata R. , Doui‐Aici M.
Published: October 2007

We present the results of first‐principles study of the structural and electronic properties of Bex Zn1–x S and Bex Zn1–x Te alloys for different concentrations x. The computational method is based on the full‐potential muffin‐tin orbitals method (FP‐LMTO) in the framework of density‐functional theory (DFT). The exchange and correlation energy is described in the local density approximation (LDA) using Perdew–Wang parameterization. We have investigated the effect of composition on the ground‐state properties, band gap and effective mass. We report the results concerning the variation of the gaps and crossover of the direct, indirect bandgap and the bowing. Using the approach of Zunger and coworkers, the microscopic origins of bandgap bowing have been detailed and explained. A reasonable agreement is found from the comparison of our results with other theoretical calculations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The impact of a home‐based spirituality teaching programme: qualitative exploration of participants' experiences
Authors: Moritz Sabine , Kelly Mary , Angen Maureen , Quan Hude , Toews John , Rickhi Badri
Published: October 2007

Context: A growing body of research reports that spiritual well‐being plays a significant role in mental wellness. Findings from a completed randomized controlled trial (RCT) indicate that a home‐based, eight‐week spirituality teaching programme lowers mood disturbance and increases quality of life. In this qualitative exploration the authors set out to understand how participants perceived the programme's impact.

Methods: This descriptive, qualitative exploration employed face‐to‐face, in‐depth interviews with 13 individuals from Calgary, Canada. Participants were self‐referred clients suffering from emotional distress and purposively sampled from the study population of the previously conducted RCT. Interviews consisted of open‐ended questions that focused on how the spirituality teaching programme may have affected mood. Interviews were transcribed verbatim and a thematic analysis was undertaken by three of the authors.

Results: Clients described how their mood and life changed throughout and subsequent to the spirituality teaching programme. The following six thematic categories were identified: (1) expansion of spiritual beliefs; (2) changed life perspectives; (3) calmness/mental clarity; (4) relief of mood disorder symptoms; (5) improved relationships; (6) renewed physical energy. Interviewees perceived the first three themes, expanded spiritual beliefs, changed life perspective and calmness, as the core changes that led to improvements in interpersonal relationships, mental health and physical energy.

Conclusion: The findings suggest that the programme used with these participants impacts on mood by expanding spiritual beliefs and by shifting perspectives of life situations, in terms of both oneself and others. Spiritual teachings and practices could be an innovative and valuable adjunct intervention to improve mood. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of diagnostic scores with adjustment for covariates
Authors: Berres M. , Zehnder A. , Bläsi S. , Monsch A. U.
Published: October 2007

Diagnostic tests yield measurements on very different types of scales. Quantitative scales may consist of non‐negative integers, either unbounded or bounded, with a fixed number of different values, or they may consist of continuous or percentage values. Remembering a different threshold value for each diagnostic variable would be cumbersome, in particular if covariates have to be taken into account. As a convenient way to overcome such problems we propose to compute z‐scores for all measurements. They will be adjusted for covariates so that any individual can be judged on any test result on one single scale with an appropriate standard normal quantile as threshold. Two issues need to be addressed: Selection of covariates in the regression model which delivers the adjustment and normality of the residuals. The first will be treated by cross‐validation and the latter by applying an appropriate transformation. We apply this methodology to neuropsychological tests and adjust for age, length of education and sex. Normality of residuals is needed on the diagnostically relevant side only. This allows to use parametric transformations, which can be easily implemented, e.g. in database systems. Since we have measurements at baseline and at follow‐up we also analyze change values in a similar manner. For ease of interpretation, we transform the resulting z‐scores back to the original scale. Copyright © 2007 John Wiley & Sons, Ltd.
A non‐inferiority test for diagnostic accuracy based on the paired partial areas under ROC curves
Authors: Li Chi‐Rong , Liao Chen‐Tuo , Liu Jen‐Pei
Published: October 2007

Non‐inferiority is a reasonable approach to assessing the diagnostic accuracy of a new diagnostic test if it provides an easier administration or reduces the cost. The area under the receiver operating characteristic (ROC) curve is one of the common measures for the overall diagnostic accuracy. However, it may not differentiate the various shapes of the ROC curves with different diagnostic significances. The partial area under the ROC curve (PAUROC) may present an alternative that can provide additional and complimentary information for some diagnostic tests which require false‐positive rate that does not exceed a certain level. Non‐parametric and maximum likelihood methods can be used for the non‐inferiority tests based on the difference in paired PAUROCs. However, their performance has not been investigated in finite samples. We propose to use the concept of generalizedp‐value to construct a non‐inferiority test for diagnostic accuracy based on the difference in paired PAUROCs. Simulation results show that the proposed non‐inferiority test not only adequately controls the size at the nominal level but also is uniformly more powerful than the non‐parametric methods. The proposed method is illustrated with a numerical example using published data. Copyright © 2007 John Wiley & Sons, Ltd.
Electrical properties and the thermal and photochemical stability of poly(vinyl chloride) films stabilized with some maleyl amide polymers
Authors: Rabie S.T. , Eid M.A.M.
Published: October 2007

Some maleyl amide polymers were prepared and evaluated as thermal and photochemical stabilizers for rigid poly(vinyl chloride) (PVC). Thermal degradation was determined by measuring the rate of dehydrochlorination potentiometrically. Also, the degree of discoloration was measured for both the thermally degraded and the photochemically degraded PVC. Dibutyltin maleate heat stabilizer was used for comparison in thermal and photodegradation. The applied polymers showed stabilizing efficiency in both thermal and photodegradation by decreasing the rate of degradation, degree of discoloration, and percentage weight loss. The amide polymer of melamine gave better stabilizing efficiency than those of p‐phenylenediamine and m‐phenylenediamine. A dielectric study was carried out over a frequency range from 100 Hz to 100 kHz at room temperature (∼22°C). The results revealed that the stabilizing effect of these maleyl amide polymers depends on the type of stabilizer and its concentration. The dielectric data for the investigated systems were found to be fitted by two absorption regions using the Fröhlich function. These regions are ascribed to the Maxwell–Wagner effect and to intramolecular motion involving the rotation of various segments of the side group as the main chain motion is restricted. The study led to a conclusion that the greater stabilizing efficiency of the melamine amide polymer may be due to the presence of a free amino group (NH2) that can participate in the stabilization process. J. VINYL ADDIT. TECHNOL., 13:206–214, 2007. © 2007 Society of Plastics Engineers
Enhancing the performance of flexible vinyl by using the formulary approach
Authors: Strepka Arron M. , Arendt William D. , Petrovich Danielle C. , Joshi Makarand
Published: October 2007

Each vinyl plastisol processor has different requirements. The features of the finished goods determine the specifications and physical properties that are critical in the manufacturing process. Processors may also have varying equipment limitations that require a specific working range of each plastisol property, such as viscosity, for acceptable processing. Although the benzoate esters have been utilized for many years by plastisol formulators and processors to their advantage, usage of these esters has been limited because of their tendency to yield high‐viscosity plastisols. By utilizing a formulary approach, it is possible to fine‐tune the properties of the plastisol, thus allowing greater latitude. Design of experiment (DOE) was employed to accomplish this objective. For this work, generic resilient‐flooring formulations were selected as the model. The formulary approach was employed to adjust the formulation and processing parameters, thereby allowing plastisol formulators and processors to develop cost‐efficient formulations. J. VINYL ADDIT. TECHNOL., 13:201–205, 2007. © 2007 Society of Plastics Engineers
Starch as antiblocking agent in breathable polyurethane membranes
Authors: Pecku Suven , van der Merwe Thilo L. , Rolfes Heidi , Focke Walter W.
Published: October 2007

A breathable polyurethane membrane was manufactured by using a multilayer film extrusion technique. In this process, the monolithic membrane is blown as the inner layer of a three‐layer film in which the outer support layers are polyethylene‐based. The neat membrane surface was unacceptably sticky. It was found that starch was a suitable antiblocking agent outperforming mineral fillers. However, starch incorporation decreased the membrane permeability towards moisture. The experimental permeability results are consistent with the predictions of the Maxwell model for a randomly dispersed, impermeable spherical filler. Fitting the Wagner‐Sillar model indicated a near‐spherical particle shape and confirmed the impermeable nature of the starch particles. This unexpected result can be rationalized by assuming a highly crystalline or glassy nature for the starch domains. J. VINYL ADDIT. TECHNOL., 13:215–220, 2007. © 2007 Society of Plastics Engineers
Copolymerization of aniline and vinyl acetate by using various surfactants in aqueous media
Authors: Eisazadeh Hossein
Published: October 2007

Polyaniline/poly(vinyl acetate) (PAn/PVAc) copolymer was prepared in aqueous solution by the copolymerization of vinyl acetate and aniline using a mixture of KIO3 and (NH4)2S2O8 as an oxidant in the presence of the surfactants sodium dodecylbenzenesulfonate, poly(ethylene glycol), and hydroxypropylcellulose. The PAn/PVAc copolymers were characterized in terms of their conductivity, morphology, and structure. The results indicated that the morphology and conductivity of the products were dependent on the type of surfactant used (anionic or nonionic). Furthermore, it was found that adding vinyl acetate monomer to the stirred aqueous solution containing oxidant, surfactant, and aniline monomer had a great effect on the morphology and increased the amount of the product. The structures of the products were determined by FTIR spectroscopy. J. VINYL ADDIT. TECHNOL., 13:229–233, 2007. © 2007 Society of Plastics Engineers
Wind turbine performance under icing conditions
Authors: Hochart Clement , Fortin Guy , Perron Jean , Ilinca Adrian
Published: October 2007

The wind energy market is in full growth in Quebec but technical difficulties due to cold climate conditions have occurred for most of the existing projects. Thus, icing simulations were carried out on a 0.2 m NACA 63 415 blade profile in the refrigerated wind tunnel of the Anti‐icing Materials International Laboratory (AMIL). The shapes and masses of the ice deposits were measured, as well as the lift and drag forces of the iced profiles. Scaling was carried out based on the 1.8 MW–Vestas V80 wind turbine technical data, for three different radial positions and two in‐fog icing conditions measured at the Murdochville wind farm in the Gaspé Peninsula. For both icing events, the mass of ice accumulated on the blade profile increased with an increase in the radial position. In wet regime testing (first icing event), glaze formed mostly near the leading edge and on the pressure side. It also accumulated by run‐off on the trailing edge of the outer half of the blade. In dry‐regime testing (second icing event), rime mostly accreted on the leading edge and formed horns. For both icing events, when glaze or rime accreted on the blade profile, lift decreased and drag increased. A load calculation using the blade element theory shows that drag force on the entire blade becomes too large compared to lift, leading to a negative torque and the stop of the wind turbine. Torque reduction is more significant on the outer third of the blade. Setting up a de‐icing system only on the outer part of the blade would enable significant decrease of heating energy costs. Copyright © 2007 John Wiley & Sons, Ltd.
Zur Kristallchemie der Oxorhenate
Authors: Müller‐Buschbaum Hanskarl
Published: October 2007

Das Review behandelt die Kristallchemie der Oxorhenate. Im Gegensatz zur Kristallchemie der kürzlich diskutierten Oxorhodate tritt Rhenium in vielfältiger Koordination auf. Zu nennen sind quadratisch planare Polygone, trigonale Bipyramiden, Tetraeder und Oktaeder. Ausgehend von den Oxiden ReO2, Re2O7, Re1,16O3, Re3O10 and ReO3 wird gezeigt, daß Oxorhenate zueinander isolierte Tetraeder, Oktaeder, Re2O10‐ und Re2O9‐Baugruppen aufweisen. Die Polyeder von Sauerstoff um Rhenium treten isoliert zueinander auf oder bilden eindimensionale Ketten, zweidimensionale Netze und dreidimensionale Gerüststrukturen. Rhenium adaptiert die Kristallstrukturen der Perowskite, des Fluorits, des Pyrochlors, Rutils und der Stapelvarianten der Perowskite. Spezielle Eigenschaften weisen die Quecksilber‐Oxorhenate (HgReO4, Hg2ReO5, Hg5Re2O10) mit – Hg+‐Hg+ – Gruppen und die Selten Erdmetall‐Oxorhenate (Ln2ReO5, Ln3Re2O9, Ln5Re2O12) mit deutlichen Re‐Re – Wechselwirkungen auf.

PbRe2O8 und BiReO4 sind bemerkenswert mit Blick auf einseitig offene Polyeder, die durch lone pair – Aktivität am Pb2+ und Bi3+ hervorgerufen werden. Die Lagen der lone pair (e2−–Punktladung) werden durch Berechnungen des Madelunganteils der Gitterenergie ermittelt.
Synthesis and Crystal Structure of a Novel A‐Zeolite‐like Copper Complex: [Cu12(SO4)12(3H2O)]·H2O
Authors: Zhang Xing‐Jing , Xing Yong‐Heng , Han Jing , Ge Mao‐Fa , Niu Shu‐Yun
Published: October 2007

The reaction of CuBr2, N(CH2CH2COOH)3, and Nd(NO3)3·6H2O in water adjusted pH = 5‐6 with H2SO4 at constant 55 °C afforded a novel three‐dimensional coordination complex [Cu12(SO4)12(3H2O)]·H2O, (1), which was characterized by IR, elemental analysis, and X‐ray diffraction. The crystal structure data of 1 as follows: Cubic, ${\rm Fm}{\bar 3}{\rm c}$, a = b = c = 24.018(2) Å, V = 13855 (3) Å3, Z = 968, Dc = 1.905 g/cm3, F(000) = 7712, R1 = 0.0352, wR2 = 0.0866 (I > 2σ(I)), R1 = 0.0449, wR2 = 0.0927 (for all data) and S = 1.075. The analysis of crystal structure indicates that the structure of 1 is similar to that of silicate zeolite (Na12[Al12Si12O48]·27H2O).