bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of gentle annular gas veil for electrospinning of polymer solutions and melts
Authors: Rein D.M. , Cohen Y. , Ronen A. , Shuster K. , Zussman E.
Published: February 2009

A novel experimental device for elevated‐temperature electrospinning of highly volatile and quickly crystallizing polymer solutions and melts was developed. The main parameters of gentle annular gas veil in electrospinning process were studied. The influence of electrical conductivity of solvent on the diameter of electrospun fibers from ultra‐high molecular weight polyethylene was experimentally determined. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Solubility of terephthalic acid in the reaction system oligomeric bishydroxybutyl terephthalates—1,4‐butanediol
Authors: Huang Hainan , Zeng Zuoxiang , Xue Weilan , Zhu Wanyu
Published: February 2009

The physical solubilities of terephthalic acid (TPA) in the reaction system oligomeric bishydroxybutyl terephthalates—1,4‐butanediol (BD) are measured using an analytic method from 449 to 507 K. The reaction system is obtained by transesterification of dimethyl terephthalate and excess BD. These results are fitted with the solubility model based on the Margules equation, and the average deviation of the model is 1.20%; the fusion enthalpies ΔHfus of TPA and infinite‐dilution activity coefficients γ∞2 in the system are obtained by regressing of the experimental data. In addition, synthetic method is chosen to determine the total solubility which is complicated by chemical reaction, the results indicate that the chemical reaction start at 452–472 K. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Trials needed to assess knee proprioception following stroke
Authors: Piriyaprasarth Pagamas , Morris Meg E. , Delany Clare , Winter Adele , Finch Sue
Published: February 2009

Background and Purpose. This study explores the number of trials required to identify clinically significant impairments in knee joint position sense and movement sense following stroke. Method. Proprioception was assessed in 33 stroke patients aged 37–87 years. Ten trials for each assessment were performed in sitting and supine positions using both verbal response techniques and contralateral limb matching. Results. Forty‐six percent of participants were identified with a proprioceptive deficit. The trial where the first incorrect response occurred varied across individuals and testing positions. Performing only one trial detected proprioceptive impairments in less than 10% patients, and incorrect responses did not always occur in the first 5 trials. In sitting, no participant failed the assessment of knee joint position sense using the verbal response technique after only 6 trials. In supine, no participant failed the assessment of knee movement sense using the verbal response technique after only 6 trials. For the assessment of knee joint position sense in sitting using contralateral limb matching an estimated 9.4% of patients with a deficit would be missed if only 3 trials were used in preference to 5. For assessment of knee joint position sense in sitting, an estimated 18.8% of patients with deficits would be missed if only 3 trials were used rather than 10 trials. Conclusions. Clinicians should perform at least 10 trials in either sitting or supine to quantify joint position sense and movement sense at the knee following stroke. Copyright © 2009 John Wiley & Sons, Ltd.
Dielectric relaxation and giant dielectric constant of Nb‐doped CaCu3Ti4O12 ceramics under dc bias voltage
Authors: Liu Peng , He Ying , Zhou Jian‐ping , Mu Chun‐hong , Zhang Huai‐wu
Published: February 2009

CaCu3Ti4–x Nbx O12 (x = 0, 0.01, 0.08, 0.2) ceramics were fabricated by a conventional solid‐state reaction method. The ceramics showed the body‐centered cubic structure without any foreign phases and the grain size decreases with Nb doping. Two Debye‐type relaxations were observed for the Nb‐doped samples at low frequency and high frequency, respectively. The complex electric modulus analysis revealed that the surface layer, grains and grain boundaries contributed to the dielectric constant. The low‐frequency dielectric constant relative to the surface layer decreased to a minimum and then increased with the dc bias voltage at 100 Hz, which were well explained in terms of a model containing two metal oxide semiconductors in series, confirming the surface layer in the ceramics. The shift voltage VB corresponding to the minimal capacitance increased with increase of the composition x. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies of giant magnetoimpedance effect of Co‐rich microwires in wide frequency range
Authors: Popov V. , Zhukova V. , Ipatov M. , García C. , Gonzalez J. , Ponomarenko V. , Berzhansky V. , Vinogorodsky D. , Zhukov A.
Published: February 2009

The GMI effect in Co‐rich amorphous microwires with nearly‐zero and negative magnetostriction constant has been investigated in the frequency range from a few MHz up to 10 GHz using conventional impedance analyzer based technique and microwave waveguide method. The GMI response of the order of 200% has been observed for all samples at MHz frequencies, while only one samples demonstrated considerable GMI ratio of about 60% at GHz frequencies. This can be explained by the fact that impedance dependence on external magnetic field in the microwaves range is affected not only by the magnetic softness of the wire material but also by the magnetic resonance conditions in the not saturated sample. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monolithically integrated UV/IR‐photodetectors based on an AlN/GaN‐based superlattice grown on an AlGaN buffer layer
Authors: Hofstetter Daniel , Baumann Esther , Giorgetta Fabrizio R. , Théron Ricardo , Guillot Fabien , Monroy Eva , Golka Sebastian , Strasser Gottfried
Published: February 2009

In this article, we demonstrate closely spaced, monolithically integrated photodetectors in two largely different wavelength ranges. The epitaxial structure of the devices was grown by plasma‐assisted molecular‐beam epitaxy on an AlN‐on‐sapphire template; it consists of a Si‐doped AlGaN thin film, and a nearly strain compensated 40 period AlN/GaN superlattice with 1.0 nm thick GaN quantum wells and 2.0 nm thick AlN barriers. The entire structure is covered with an AlGaN cap layer. The superlattice acts as active region for the infrared detector, while the AlGaN buffer layer serves as active area for the ultraviolet detector. While the photovoltaic near‐infrared detector has a center wavelength of 1.37 μm, the photoconductive ultraviolet detector has a long wavelength cutoff at 250 nm. The two detectors could be operated up to room temperature with reasonable sensitivities. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel tunable phosphor‐free white III‐nitride light emitting diodes based on indium rich InGaN nanostructures
Authors: Soh C. B. , Liu W. , Chua S. J. , Teng J. H. , Tan Rayson J. N. , Ang S. S.
Published: February 2009

Phosphor free tunable white light emitting diodes (LEDs) have been fabricated using stacked InGaN/GaN quantum wells (QWs) comprised of a lower set of red emitting QWs with an upper set of blue and green emitting QW layers. With antisurfactant treatment, indium rich InGaN nanostructures are incorporated in the InGaN/GaN quantum well during growth. AFM study shows the formation of InGaN nanostructures with an average diameter of 40‐80 nm in the quantum well layer. This growth technique enables red emitting III‐Nitride based LEDs to be generated. With the growth of additional stacked blue/green QWs on these red emitting QWs with InGaN nanostructure incorporation for white light generation, competition arises between the quantum well layers for thermalization of injected carriers. The transport of holes from the p‐GaN layer determines the radiative recombination event as holes have a lower mobility than electrons. At low injection current, emission from the upper blue/green QWs layer dominates where electron–hole (e–h) pair recombination takes place. With higher injection current, more holes diffuse across the GaN barrier to recombine with electrons at the InGaN nanostructures in the lower sets of QWs. Based on the band structure for the stacked QWs, the existence of these In‐rich nanostructures leads to more effective carrier trapping at the lower set of QWs as electrons have to overcome an additional potential barrier (at the interface of InGaN nanostructures to the InGaN well layer). There is also a higher tendency for thermalization of carriers at the lower energy states. The effect of band filling under higher injection current also enables the excess holes to recombine at the lower set of QW layers with indium rich nanostructure, which accounts for the continuous increase in higher emission wavelength from the EL spectra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental method for scanning the surface depletion region in nitride based heterostructures
Authors: Netzel Carsten , Skriniarova Jaroslava , Herms Martin , Wenzel Hans , Hoffmann Veit , Knauer Arne , Weyers Markus
Published: February 2009

The group‐III‐nitride semiconductors feature strong spontaneous polarization in the [0001] direction and charges on the respective polar surfaces. Within the resulting surface depletion region the surface field causes band banding and affects the optical transitions in quantum wells. We studied the changes of the emission characteristics of a single GaInN quantum well when its distance to the surface and the influence of the surface field varies. We observe a strong increase of the quantum well emission energy and a decrease of the line width when the surface field partially compensates the piezoelectric field of the quantum well. A scan of the total surface depletion region with a single quantum well as probe was performed. The obtained emission data allow for the direct determination of the width of the depletion region. The experimental method is promising for studies of the surface field and the surface potential of III‐nitride surfaces and interfaces. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement in electrical properties of GaN heterostructure field‐effect transistor by Si atom deposition on AlGaN barrier surface
Authors: Onojima Norio , Hirose Nobumitsu , Mimura Takashi , Matsui Toshiaki
Published: February 2009

This study demonstrates that deposition of Si atoms on AlGaN barrier surfaces in GaN heterostructure field‐effect transistors (HFETs) can modulate the electrical properties of the two‐dimensional electron gas (2DEG). The results of Hall measurements performed using the eddy current and four‐point van der Pauw methods showed that the sheet resistance of an AlGaN/GaN HFET sample without surface passivation increased from that of the unprocessed sample after post‐metallization annealing at 820 °C for ohmic contacts. In contrast, the sheet resistance of the Si‐deposited sample did not increase even after annealing. Furthermore, eddy current measurements for unprocessed wafers with and without Si deposition revealed that the sheet resistance can be reduced by depositing Si atoms, regardless of annealing. The effect of Si deposition on devices having a thin Al‐rich barrier layer was found to be significant. The deposition of Si atoms (2 nm) on the AlN barrier surface in an AlN/GaN HFET (AlN 2 nm) resulted in a remarkable decrease in the sheet resistance from 60356 to 388 Ω/sq. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
HVPE growth of AlxGa1–xN alloy layers
Authors: Hagedorn Sylvia , Richter Eberhard , Netzel Carsten , Zeimer Ute , Weyers Markus , Tränkle Günther
Published: February 2009

In this work growth of AlxGa1–xN layers (0 < x < 0.91) by hydride vapour phase epitaxy (HVPE) is presented. The growth process is performed in a modified horizontal reactor. The measured compositions show good agreement with theoretical values calculated from a heterogeneous thermodynamic equilibrium model. The aluminum mole fractions, the homogeneity and the relaxation of the AlxGa1–xN layers are deduced from x‐ray diffraction (XRD) measurements. Cathodoluminescence (CL) investigations of an Al0.52Ga0.48N sample exhibit a luminescence peak energy near the expected band edge and an additional luminescence peak between the AlxGa1–xN and the GaN bandgap. From XRD and spatially resolved CL measurements the peak at lower energy can be associated to crystallites with orientation different from the c‐plane bulk layer that are formed on the growing surface. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of 3D InGaN/GaN structures providing semipolar GaN planes for efficient green light emission
Authors: Wunderer T. , Lipski F. , Hertkorn J. , Schwaiger S. , Scholz F.
Published: February 2009

A fabrication method for the formation of 3D GaN structures with reduced piezoelectric field is presented. Via optimized selective epitaxy the surface is just composed of hexagonally patterned semipolar {1$ \bar 1 $01} or {11$ \bar 2 $2} planes. GaN growth with less NH3 at a higher growth speed, a doubled effective area and good light outcoupling properties compared to c‐plane growth are additional advantages of this effective technique.

The high material quality is confirmed via PL measurements. No defect related optical transitions, often observed in non‐ and semipolar GaN, were found. An In‐GaN QW grown on these semipolar planes showed efficient green (522 nm) light emission in spite of a reduced influence of the quantum confined stark effect (QCSE) (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MOCVD growth and optical study of InGaN quantum dots and their emitters on a high quality GaN layer grown using a high temperature AlN as buffer
Authors: Wang Q. , Bai J. , Wang T. , Cullis A. G. , Parbrook P. J. , Ranalli F.
Published: February 2009

The optical properties have been investigated on InGaN quantum dots (QDs) with density up to 9× 1010/cm2 and excellent uniformity grown on a high quality GaN surface grown using high temperature AlN as a buffer layer on sapphire. A stimulated emission from the multiple layers of InGaN QDs has been observed under an optical pumping with a low threshold at room temperature indicating a superior optical quality. Moreover, InGaN QD based light emitting diodes (LEDs) with good performances have been grown and fabricated, and then the influence of the thermal annealing for p‐type GaN activation on the optical properties of the InGaN QD based LEDs has been studied. It has been found that the optimized annealing conditions for p‐type GaN activation can lead to significantly improved performance of the InGaN QD based LEDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical spectroscopy of InGaN‐GaN quantum dot ensembles
Authors: Davies Samuel C. , Mowbray David J. , Parbrook Peter J. , Ranalli Fabio , Wang Tao
Published: February 2009

InGaN‐GaN quantum dots (QDs) have been grown, with variations in the deposition time used to vary the properties of the dots. Atomic force microscopy (AFM) studies of uncapped dots indicate a small increase in dot density with increasing deposition time. Photoluminescence (PL) spectroscopy at low temperatures reveals a red shift of the dot emission as the deposition time is increased. Power dependent PL measurements indicate that it is relatively easy to saturate the QD ground state emission because of their low density and expected long carrier lifetime.

Emission from an excited state is observed for high excitation powers. With increasing deposition time the activation energy which determines the high temperature quenching of the dot PL is found to increase. Photoluminescence excitation (PLE) reveals a continuum of states below the GaN band edge which is attributed to the presence of a wetting layer (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties and modal gain of InGaN quantum dot stacks
Authors: Kalden Joachim , Sebald Kathrin , Gutowski Jürgen , Tessarek Chistian , Aschenbrenner Timo , Figge Stephan , Hommel Detlef
Published: February 2009

We present investigations of the optical properties of stacked InGaN quantum dot layers and demonstrate their advantage over single quantum dot layer structures. Measurements were performed on structures containing a single layer with quantum dots or threefold stacked quantum dot layers, respectively. A superlinear increase of the quantum dot related photoluminescence is detected with increasing number of quantum dot layers while other relevant GaN related spectral features are much less intensive when compared to the photoluminescence of a single quantum dot layer. The quantum dot character of the active material is verified by microphotoluminescence experiments at different temperatures. For the possible integration within optical devices in the future the threshold power density was investigated as well as the modal gain by using the variable stripe length method. As the threshold is 670 kW/cm2 at 13 K, the modal gain maximum is at 50 cm–1. In contrast to these limited total values, the modal gain per quantum dot is as high as 10–9cm–1, being comparable to the IIVI and III‐As compounds. These results are a promising first step towards bright low threshold InGaN quantum dot based light emitting devices in the near future (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extremely high hole concentrations in c‐plane GaN
Authors: Trybus Elaissa , Doolittle W. Alan , Moseley Michael , Henderson Walter , Billingsley Daniel , Namkoong Gon , Look David C.
Published: February 2009

Metal Modulated Epitaxy (S. D. Burnham et al., J. Appl. Phys. 104, 024902 (2008) [1]) is extended to include modulation of both the shutters of Ga and Mg, the Mg being delivered from a Veeco corrosive series valved cracker (S. D. Burnham et al., Mater. Res. Soc. Proc. 798, Y8.11 (2003) [2]). The Ga fluxes used are sufficiently large that droplets rapidly form when the Ga shutter opens and are subsequently depleted when the Ga shutter closes. The result is the ability to limit surface faceting while predominantly growing under average N‐rich growth conditions and thus, possibly reduce N‐vacancy defects. N‐vacancy defects are known to result in compensation. This ability to grow higher quality materials under N‐rich conditions results in very high hole concentrations and low resistivity p‐type materials. Hole concentrations as high as 2×1019 cm–3 have been achieved on c‐plane GaN resulting in resistivities as low as 0.38 ohm‐cm. The dependence on Ga flux, shutter timing, the corresponding RHEED images for each condition is detailed and clearly show minimization of faceting and crystal quality variations as determined by X‐ray diffraction. Quantification of the Mg incorporation and residual impurities such as hydrogen, oxygen, and carbon by SIMS, eliminates co‐doping, while temperature dependent hall measurements show reduced activation energies. X‐ray diffraction data compares crystalline quality with hole concentration. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Urea as a protein destabilizing agent in electrospray ionisation
Authors: Donald Lynda J. , Collado Vladimir M. , Galka Jamie J. , O'Neil Joe D. , Duckworth Harry W. , Loewen Peter C. , Standing Kenneth G.
Published: February 2009

Urea is well known as a denaturant of proteins, but there is also evidence that millimolar amounts of urea may in fact stabilize protein complexes. Advances in mass spectrometric analysis have given us the opportunity to test the effect of urea on several noncovalent complexes in buffered solutions. We expected to see lower charge states if folded proteins were more compact (and therefore more stable), and higher charge states if the proteins were denatured. We have found that mM urea interferes with some noncovalent interactions, and that the extent of interference depends on the specific protein complex. The difference seems to be related to the type of interactions, with weak ones, such as H‐bonds, more sensitive to urea. Examples show that a quick check with urea may give some insights into protein stability in the mass spectrometer. Copyright © 2009 John Wiley & Sons, Ltd.
Bronze Age volcanic event recorded in stalagmites by combined isotope and trace element studies
Authors: Siklósy Zoltán , Demény Attila , Vennemann Torsten W. , Pilet Sebastien , Kramers Jan , Leél‐Őssy Szabolcs , Bondár Mária , Shen Chuan‐Chou , Hegner Ernst
Published: February 2009

Stable isotope analyses of speleothems (carbonate deposits formed in caves) have been widely used to reconstruct paleoenvironmental conditions. Recent improvements in geochemical techniques have enabled us to analyze climate‐influenced deposits at high temporal resolution so that hitherto unrecognized environmental conditions may be identified. Stable H, C and O isotope analyses on carbonate and inclusion water have been combined with multicollector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) age dating and laser‐ablation ICP‐MS trace element analyses on a stalagmite from southern Hungary. The study reveals significant changes in chemical and isotopic compositions of the speleothem between approx. 3800 and 3500 years BP (‘Before Present’) indicating coupled changes in the temperature and precipitation regime under which the speleothem formed. Stable isotopic and trace element correlations within this time period correlate with similar studies of stalagmites of comparable age from the Alpine‐Mediterranean region. Our studies suggest that traces of deposition of volcanic dust, possibly related to the Thera eruption of Santorini (Greece) ca. 1650 BC (∼3650 BP), and environmental changes can be detected at a distance of several thousand kilometers. Copyright © 2009 John Wiley & Sons, Ltd.
Fast screening and quantitative evaluation of internally deleted goat αs1‐casein variants by mass spectrometric detection of the signature peptides
Authors: Picariello Gianluca , Ferranti Pasquale , Caira Simonetta , Fierro Olga , Chianese Lina , Addeo Francesco
Published: February 2009

Currently, the internally deleted caprine αs1‐casein (αs1‐CN) variants F and G, associated with low casein expression, are detected by means of ordinary descriptive techniques. No relevant procedure is available to detect internally deleted goat αs1‐CN in bulk milks. The availability of full‐length and αs1‐CN F and G variants allowed us to further investigate this issue. Using matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry (MS) and high‐performance liquid chromatography (HPLC)/electrospray ionization (ESI)‐MS and ESI‐MS/MS, tryptic signature peptides αs1‐CN F f59‐63/f43‐63, αs1‐CN G f4‐20/f4‐21, αs1‐CN B2 f4‐22 Pro16 and αs1‐CN A f4‐22 Leu16 were identified. This also helped to solve the interesting question of how the casein variants contribute to the composition of goat's bulk milk. Synthetic peptide analogues with ionization efficiency equivalent to that of tryptic junction peptides were used as internal standards to evaluate αs1‐CN variants, either individually or globally, using bulk milk from a single goat breed as a model system. Here, αs1‐CN F accounted for 0.15 ± 0.08% and the αs1‐CN G variant was missing or below the 0.10% detection limit. The analysis of six samples confirmed that αs1‐CN G was missing and that αs1‐CN F occurred at a low frequency in hybrid and local breed bulk milks from Mediterranean areas. In conclusion, a quantitative MS‐based application of the signature peptides for full‐length and internally deleted variants in goat's casein is provided. The strategy is also suggested for the determination of splice variants in any biological sample. Copyright © 2009 John Wiley & Sons, Ltd.
A new design of delay‐dependent robust ℋ︁∞ filtering for continuous‐time polytopic systems with time‐varying delay
Authors: Qiu Jianbin , Feng Gang , Yang Jie
Published: February 2009

This paper revisits the problem of delay‐dependent robust ℋ∞ filtering design for a class of continuous‐time polytopic linear systems with a time‐varying state delay. Based on a newly developed parameter‐dependent Lyapunov–Krasovskii functional combined with Projection Lemma and an improved free‐weighting matrix technique for delay‐dependent criteria, a new sufficient condition for robust ℋ∞ performance analysis is first derived and then the filter synthesis is developed by using a simple matrix inequality linearization technique. It is shown that the desired filters can be constructed by solving a set of linear matrix inequalities. Finally, two simulation examples are given to show the effectiveness and less conservatism of the proposed method in comparison with the existing approaches. Copyright © 2009 John Wiley & Sons, Ltd.
An evaluation of code similarity identification for the grow‐and‐prune model
Authors: Mende Thilo , Koschke Rainer , Beckwermert Felix
Published: February 2009

In case new functionality is required, which is similar to the existing one, developers often copy the code that implements the existing functionality and adjust the copy to the new requirements. The result of the copying is code growth. If developers face maintenance problems, because of the need to make changes multiple times for the original and all its copies, they may decide to merge the original and its copies again; that is, they prune the code. This approach was named the grow‐and‐prune model by Faust and Verhoef. This paper describes tool support for the grow‐and‐prune model in the evolution of software by identifying similar functions that may be merged. These functions are identified in two steps. First, token‐based clone detection is used to detect pairs of functions sharing code. Second, Levenshtein distance (LD) measures the textual similarity among these functions. Sufficient similarity at function level is then lifted to the architectural level. The approach is evaluated by a case study for the Linux kernel. We give examples of instances of the grow‐and‐prune model for Linux. Then, we evaluate our technique quantitatively by measuring recall and precision with respect to an oracle. To obtain the oracle, we asked nine different developers to decide whether they believe certain functions are similar and should be merged. The evaluation shows that the recall and precision of our technique are about 75%. Calculating LD on token values rather than characters is superior. The two metrics strongly correlate but the token‐based calculation reduces runtime by a factor of 4.6. Clone detection is an effective filter to reduce the number of calculations of the relatively expensive LD. Copyright © 2009 John Wiley & Sons, Ltd.
[AlCp2]+: Structure, Properties and Isobutene Polymerization
Authors: Huber Michael , Kurek Alexander , Krossing Ingo , Mülhaupt Rolf , Schnöckel Hansgeorg
Published: February 2009

Reaction of the protonic ether compound [H(OEt2)2][Al(ORF)4] (RF = C(CF3)3) with AlCp3 leads to the formation of the [AlCp2]+‐cation, which is stabilized by the weakly coordinating [Al(ORF)4]– ion. Besides [AlCp2]+, the ion [AlCp2·2Et2O]+, which is stabilized by two ether molecules, is formed in an equilibrium reaction. The so far unknown molecular structure of [AlCp2]+ and the molecular structure of [AlCp2·2Et2O]+ are presented in this work. To get insight in the formation and the equilibrium between these two cations, quantum mechanical calculations were performed. Moreover, the influence of counterions like [Al(ORF)4]– and [MeB(C6F5)3]– on the activity of [AlCp2]+ to act as a polymerization initiating agent for isobutene was investigated.
Tri‐, Penta‐, and Octaiodide Salts of Transition Metal Polyether Complexes
Authors: Fiolka Christoph , Striebinger Ralph , Walter Thomas , Walbaum Christine , Pantenburg Ingo
Published: February 2009

Salts of transition metal cations complexed by 12‐crown‐4, benzo‐15‐crown‐5 or 18‐crown‐6 with I3–, I5– and I82– anions, are synthesized and their crystal structures are determined bysingle X‐ray diffraction. The crystal structures of 1, 2 and 3are built up by three different cations with the compositions [Fe(H2O)6(12c4)6]2+, [Zn(H2O)2(b15c5)3]2+, [Zn(H2O)5(18c6)2]2+, and isolated triiodide anions I3–, respectively. Aside from the cations, the isotypic iron and copper compounds (4, 5) contain crystallographically independent V‐shaped pentaiodide anions which are linked to dimers by weak interionic contacts. Furthermore, the structures contain centrosymmetric I82– anions. An investigation of possible secondary contacts reveals that the iodine substructure of 4 and 5 consists of essentially isolated octaiodide units.
Site Occupation Reversal in the C14 Laves Phase Nb(Cr1–xCox)2
Authors: Kerkau Alexander , Grüner Daniel , Ormeci Alim , Prots Yurii , Borrmann Horst , Schnelle Walter , Bischoff Ewald , Grin Yurii , Kreiner Guido
Published: February 2009

The C14 phase Nb(Cr1–xCox)2 forms within a broad homogeneity range of 0.127(3) ≤ x ≤ 0.937(8) at 1100 °C. The distribution of chromium and cobalt atoms on the crystallographic positions 2a and 6h has been studied by single crystal structure analysis and a statistical mechanics approach using energies from first‐principles full potential electronic structure calculations. For the first time a preferential occupation of the minority component on the 2a site has been observed. The calculations support a preferential site occupation with a reversal close to equal chromium and cobalt content.
Syntheses, Properties, and Structures of Bis(trifluorovinyl) Tellurium Compounds
Authors: Naumann Dieter , Tyrra Wieland , von Foullon Alexander , Pantenburg Ingo
Published: February 2009

The reaction of AgC2F3, prepared from Me3SiC2F3 and AgF, with elemental tellurium in propionitrile yields solutions of Te(C2F3)2. Oxidations of these solutions with either xenon difluoride, elemental chlorine or bromine give the corresponding bis(trifluorovinyl)tellurium dihalides Te(C2F3)2F2, Te(C2F3)2Cl2 and Te(C2F3)2Br2 in moderate yields. Ligand exchangebetween Te(C2F3)2F2 and trifluoroacetic acid anhydride yields Te(C2F3)2(OCOCF3)2. Further attempted exchange reactions resulted in complex mixtures. At –78 °C Te(C2F3)2F2 reacts with fluoride ions with formation of the ion [Te(C2F3)2F3]–, which decomposes already at –40 °C under formation of mainly [Te(C2F3)F4]– and Te(C2F3)2. The solid‐state structures of Te(C2F3)2F2, Te(C2F3)2Cl2, Te(C2F3)2Br2 and Te(C2F3)2(OCOCF3)2 have been elucidated.
Chronological expression of Wnt target genes Ccnd1, Myc, Cdkn1a, Tfrc, Plf1 and Ramp3
Authors: Röhrs Sonja , Kutzner Nadine , Vlad Annica , Grunwald Thomas , Ziegler Slava , Müller Oliver
Published: February 2009

The canonical Wnt pathway regulates several biological processes including development, cell growth and proliferation via consecutive gene regulation. A high number of target genes of the Wnt pathway has been identified, but the chronological order of target gene expression is still elusive. This order is supposed to be crucial for the controlled course of events downstream of the activated Wnt pathway. Here we present the expression chronologies of the target genes Ccnd1 (encoding for cyclin D1), Myc (c‐Myc), Cdkn1a (p21CIP1/WAF1), Tfrc (Transferrin receptor 1), Plf1 (Proliferin‐1) and Ramp3 (Receptor activity‐modifying protein 3) in C57MG cells after stimulation with Wnt‐3a. We discriminated between immediate (below 1 h), early (between 1 and 6 h), intermediate (between 6 and 12 h) and late (after 12 h) targets. According to this classification Myc and Tfrc belong to the immediate target genes; Ccnd1, Plf1 and Ramp3 are early target genes and Cdkn1a is an intermediate target gene.
Adolescents' experiences of a parent's serious illness and death
Authors: Dehlin Lena , Reg Lena Mårtensson
Published: February 2009

Objective:

Adolescence is characterized by increasing liberation from parents as the young person evolves into an independent individual. Experiencing the serious illness and death of a parent during this phase implies great stress. Serious illness involves uncertainty, worry, and hope at the same time that it is necessary for everyday life to function. This study sought to describe adolescents' experiences in the serious illness and death of a parent.

Methods:

The study was carried out using a qualitative method. Data were collected in interviews with five adolescents who were 14–17 years of age when one of their parents died.

Results:

The results show that the parent's illness was a strong threat, as the adolescents understood that their own and the family's lives would be greatly changed by the illness/death. The incomprehensibility of the parent's serious illness and death was a threatening condition on its own. The adolescents strived to make the inconceivable more conceivable to understand what was happening. They also described the necessity of finding different ways of relating to and managing the threat, such as restoring order, seeking closeness, adapting, gaining control, avoiding talking about the illness, not accepting and counting the parent out. The adolescents described feelings of being alone and alienated, even though they were close to family and friends and they did not actively seek support. The lives of the adolescents were changed by their experiences, beyond their bereavement over the parent. They felt that they had become more mature than their friends and that there had been a change in their thinking about life, changes in values, and changes in their views of relationships with other people.

Significance of results:

The results of the present study can form a basis for developing a support program whose purpose would be to prevent effects on health.
The project ENABLE II randomized controlled trial to improve palliative care for rural patients with advanced cancer: Baseline findings, methodological challenges, and solutions
Authors: Bakitas Marie , Lyons Kathleen Doyle , Hegel Mark T. , Balan Stefan , Barnett Kathleen N. , Brokaw Frances C. , Byock Ira R. , Hull Jay G. , Li Zhongze , Mckinstry Elizabeth , Seville Janette L. , Ahles Tim A.
Published: February 2009

Objective:

There is a paucity of randomized controlled trials (RCTs) to evaluate models of palliative care. Although interventions vary, all have faced a variety of methodological challenges including adequate recruitment, missing data, and contamination of the control group. We describe the ENABLE II intervention, methods, and sample baseline characteristics to increase intervention and methodological transparency, and to describe our solutions to selected methodological issues.

Methods:

Half of the participants recruited from our rural U.S. comprehensive cancer center and affiliated clinics were randomly assigned to a phone-based, nurse-led educational, care coordination palliative care intervention model. Intervention services were provided to half of the participants weekly for the first month and then monthly until death, including bereavement follow-up call to the caregiver. The other half of the participants were assigned to care as usual. Symptoms, quality of life, mood, and functional status were assessed every 3 months until death.

Results:

Baseline data of 279 participants were similar to normative samples. Solutions to methodological challenges of recruitment, missing data, and “usual care” control group contamination are described.

Significance of results:

It is feasible to overcome many of the methodological challenges to conducting a rigorous palliative care RCT.
The spiritual meaning of pre-loss music therapy to bereaved caregivers of advanced cancer patients
Authors: Magill Lucanne
Published: February 2009

Objective:

The aim of this study was to learn how music therapy sessions, held prior to the death of a loved one, impact spirituality in surviving caregivers of advanced cancer patients.

Method:

The method of naturalistic inquiry was used to investigate the spiritual meaning of pre-loss music therapy sessions. Bereaved caregivers of seven different patients, who had been receiving music therapy through a home-based hospice program, participated in individual open-ended interviews. Interviews were recorded, transcribed, and coded. Themes were organized as they emerged.

Results:

As caregivers reflected on their experiences in music therapy, they reported autonomous joy (music therapy affected the caregiver directly) and empathic joy (caregivers' joy was based in remembering seeing the patient happy in music therapy). They also noted feelings of empowerment due to the ways they felt they had contributed in the care of the patients through music therapy. The caregivers were found to engage in processes of reflection that inspired these spiritual themes: reflection on the present (connectedness), reflection on the past (remembrance), and reflection on the future (hope). They referred to the ways that the music therapy sessions helped them find connection with self, others (through bringing their loved ones “back to life” and have a “renewal of self”), and the “beyond”; and that times in music therapy brought them happy memories and sentiments of hope. Meaning through transcendence was found to be the overarching trend in this study, as caregivers were lifted from remorse into heightened sense of meaning and gained “airplane views” of their lives.

Significance of results:

Pre-loss music therapy can potentially assist caregivers during times of bereavement, as they retain memories of joy and empowerment, rather than memories of pain and distress, and find meaning through transcendence.
Numerical study of degradation of fluvial hanging valleys due to climate change
Authors: Goode Joseph K. , Burbank Douglas W.
Published: February 2009

Hanging fluvial valleys form at mouths of tributaries that are unable to incise as quickly as the trunk stream. Although hanging valleys at tributary mouths are uncommon, in very rapidly eroding ranges, such as the Himalaya, they can attain heights of ∼1 km and display mean channel slopes exceeding 30°. Given a hypothesis based on bed load–saltation erosion for how such features form, this study addresses the question of why hanging valleys are not more common and what limits their growth. We implement a numerical model of bed load–saltation erosion for a tributary junction experiencing base‐level fall to explore conditions that may lead hanging valleys to form or subsequently degrade owing to climate variability. We find that increased frequency of bed load mobilization and enhanced bed load supply can drive the degradation of hanging fluvial valleys. Moreover, when trunk aggradation overtops the hanging valley, the knickpoint tends to be removed during subsequent degradation of the alluvial surface. Channel narrowing, increased bed load size, or bed load supply each can inhibit the formation of hanging fluvial valleys. Under steady hydrological and sedimentologic conditions, bed load–saltation models predict hanging valleys could be quite common where main stem erosion is rapid. The frequency and magnitude of changes in climatically modulated sediment loads in natural systems, however, typically overwhelm factors that promote hanging valley formation without such bed load variability. Because rates of channel aggradation commonly outpace rates of hanging valley formation, we propose that hanging valleys tend to be preserved only in regimes where trunk‐stream erosion exceeds several millimeters per year.
Natural variability and anthropogenic trends in oceanic oxygen in a coupled carbon cycle–climate model ensemble
Authors: Frölicher T. L. , Joos F. , Plattner G.‐K. , Steinacher M. , Doney S. C.
Published: February 2009

Internal and externally forced variability in oceanic oxygen (O2) are investigated on different spatiotemporal scales using a six‐member ensemble from the National Center for Atmospheric Research CSM1.4‐carbon coupled climate model. The oceanic O2 inventory is projected to decrease significantly in global warming simulations of the 20th and 21st centuries. The anthropogenically forced O2 decrease is partly compensated by volcanic eruptions, which cause considerable interannual to decadal variability. Volcanic perturbations in oceanic oxygen concentrations gradually penetrate the ocean's top 500 m and persist for several years. While well identified on global scales, the detection and attribution of local O2 changes to volcanic forcing is difficult because of unforced variability. Internal climate modes can substantially contribute to surface and subsurface O2 variability. Variability in the North Atlantic and North Pacific are associated with changes in the North Atlantic Oscillation and Pacific Decadal Oscillation indexes. Simulated decadal variability compares well with observed O2 changes in the North Atlantic, suggesting that the model captures key mechanisms of late 20th century O2 variability, but the model appears to underestimate variability in the North Pacific. Our results suggest that large interannual to decadal variations and limited data availability make the detection of human‐induced O2 changes currently challenging.
Home seismometer for earthquake early warning
Authors: Horiuchi Shigeki , Horiuchi Yuko , Yamamoto Shunroku , Nakamura Hiromitsu , Wu Changjiang , Rydelek Paul A. , Kachi Masaaki
Published: February 2009

The Japan Meteorological Agency (JMA) has started the practical service of Earthquake Early Warning (EEW) and a very dense deployment of receiving units is expected in the near future. The receiving/alarm unit of an EEW system is equipped with a CPU and memory and is on‐line via the internet. By adding an inexpensive seismometer and A/D converter, this unit is transformed into a real‐time seismic observatory, which we are calling a home seismometer. If the home seismometer is incorporated in the standard receiving unit of EEW, then the number of seismic observatories will be drastically increased. Since the background noise inside a house caused by human activity may be very large, we have developed specialized software for on‐site warning using the home seismometer. We tested our software and found that our algorithm can correctly distinguish between noise and earthquakes for nearly all the events.
Macro‐scale exhaustion of surface phosphate by dinitrogen fixation in the western North Pacific
Authors: Hashihama Fuminori , Furuya Ken , Kitajima Satoshi , Takeda Shigenobu , Takemura Toshihiko , Kanda Jota
Published: February 2009

In the subtropical oceans, nutrient concentrations are frequently below the detection limits of standard analytical methods. We applied a highly sensitive method to the surface water of the western and central Pacific between 42°N and 40°S and between 141°E and 158°W except in the equatorial zone, and detected overall depletion of nitrate + nitrite and an excess of SRP. However, a remarkable exception was found: an almost complete exhaustion of SRP (<10 nM) existed at a horizontal scale of >2000 km in the western subtropical North Pacific in both summer and winter. The SRP exhaustion was a consequence of an elevated dinitrogen fixation, which occurred in areas with high dust deposition from the Asian continent that likely enhanced SRP consumption. A coupling among nutrient dynamics, dinitrogen fixation and dust deposition produces the extremely low P availability spanning a large area, which appears to be unique to the western North Pacific.
THEMIS observations of mirror structures: Magnetic holes and instability threshold
Authors: Balikhin M. A. , Sagdeev R. Z. , Walker S. N. , Pokhotelov O. A. , Sibeck D. G. , Beloff N. , Dudnikova G.
Published: February 2009

Nonpropagating mirror‐mode structures are commonly observed in many regions of natural plasma such as solar wind, planetary magnetosheaths, in cometary plasma, Io wake, terrestrial ring current and even on the outskirts of solar system. Mirror structures are typically observed in the shape of magnetic holes or peaks. Fast survey mode plasma data from the THEMIS satellites are used to solve the puzzle of how mirror structures in the form of dips can be observed in the regions of mirror stable plasma. THEMIS data also show that for mirror structures with spatial scales that considerably exceed ion Larmor radius the perpendicular temperature anticorrelates with the strength of the magnetic field. This contradiction with the conservation of adiabatic invariants is explained by the role of trapped particles.
Contributions of the driven process and the loading‐unloading process during substorms: A study based on the IMAGE‐SI12 imager
Authors: Blockx C. , Gérard J.‐C. , Coumans V. , Hubert B. , Meurant M.
Published: February 2009

Substorm energetics has been shown to have two components, the “loading‐unloading” component releasing energy previously stored in the tail and the “directly driven” component dissipating simultaneously fed solar wind energy. Previous studies disagree about the relative importance of each process. The SI12 spectral imager onboard the IMAGE satellite provides images of the Doppler‐shifted Lyman α auroral emission at 121.8 nm every 2 min. It has been used to determine the auroral intensity during substorms, which may be compared to the solar wind characteristics and interplanetary magnetic field components before and/or after substorm onsets. In this study, we analyze 256 substorms between June 2000 and December 2002, which satisfy criteria relative to the viewing conditions. We compare the mean nightside intensity during the expansion phase with the magnetic open flux, the epsilon parameter, and other coupling functions (used as proxies of transfer of solar wind energy to the magnetosphere) integrated over the growth phase or the expansion phase. The mean auroral intensity during the expansion phase correlates well with coupling functions integrated over the growth phase. We also find that the correlation between the auroral precipitation during the expansion phase and the coupling functions integrated over the expansion phase is lower but still significant. This implies that, even though both mechanisms contribute to the energy precipitated during substorms, the loading‐unloading process is statistically dominant.
Composition of energetic particles in the Jovian magnetotail
Authors: Haggerty D. K. , Hill M. E. , McNutt R. L. , Paranicas C.
Published: February 2009

The New Horizons spacecraft offered a unique opportunity to explore the distant Jovian magnetotail to over 2565 Jovian Radii. Previous observations of ion abundances were available only out to ∼150 Jovian Radii. During the 100+‐day exploration of the magnetotail, New Horizons observed a number of energetic particle bursts, similar to particle bursts observed by Galileo much closer to Jupiter. We examine the composition of these dynamic structures and compare the ion abundances with those found in more quiescent regions. We show that the composition of these energetic bursts is Iogenic and suggest it is within these bursts that Jupiter releases the bulk of its energetic material. We report on the ion composition ratios as a function distance down the Jovian magnetotail, finding an increasing intrusion of interplanetary He into the tail with distance from the planet. These observations show that the radial gradients in particle flux observed by Galileo in the magnetotail close to Jupiter extend deep into the magnetotail. We observed large electron intensities at the noon magnetopause crossing and continuous strong 10‐h modulations in electron intensity to nearly 500 Jovian Radii toward the tail. Our current hypothesis is that Jupiter enforces azimuthal rotation on some fields to distances of over a few hundred Jovian Radii. At distances greater than 500 Jovian Radii we observed long‐duration periods of strong electron anisotropy beaming down the magnetotail. Intermittent observations of 10‐h electron modulations continue into distant regions of the magnetotail and we suggest these are a signature of occasional field line connection to the magnetosphere.