bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractInGaN‐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

AbstractWe 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

AbstractMetal 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

AbstractUrea 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

AbstractStable 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

AbstractCurrently, 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

AbstractThis 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

AbstractIn 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

AbstractReaction 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

AbstractSalts 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

ABSTRACTObjective: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

ABSTRACTObjective: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

ABSTRACTObjective: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.