bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Conductivity Reduction Paths in Thermoelectric Materials
Authors: Godart Claude , Goncalves Antonio , Lopes Elsa , Villeroy Benjamin 
Published: June 2009

AbstractThe figure of merit ZT = sS2T/k (S the Seebeck coefficient, s and k the electrical and thermal conductivity respectively) is an essential element of the efficiency of a thermoelectric material for applications which convert heat to electricity or, conversely, electric current to cooling. From the expression of the power factor sS2 it was deduced that a highly degenerated semiconductor is necessary. In order to reduce the lattice part of the thermal conductivity, various mechanisms were tested in new thermoelectric materials and those had been the topics of several reviews. These include cage-like materials, effects of vacancies, solid solutions, complex structures (cluster, tunnel, …,), micro- and nano-structured systems, and more recently semiconducting glasses. We plan to review such aspects in the modern thermoelectric materials and include results of the very last years. Moreover, as micro- and nano-composites seem to be promising to increase ZT in large size samples, we will also briefly discuss the interest of spark plasma sintering technique to preserve the micro- or nano- structure in highly densified samples.
Thermoelectric Power Factor of Polycrystalline La0.75Sr0.25Co1-xMnxO3-δCeramics
Authors: Rodríguez Julio E. , Niño J. A. 
Published: June 2009

AbstractThermoelectric properties of polycrystalline La0.75Sr0.25Co1-xMnxO3-δ(0<x<0.08) (LSCoO-Mn) compounds have been studied. The samples were grown by solid-state reaction method; their transport properties were studied in the temperature range between 100 and 290K, as a function of temperature and the manganese content. The Seebeck coefficient (S) is positive over the measured temperature range and its magnitude increases with the manganese content up to values close to 160 μV/K. The electrical resistivity (ρ) goes from metallic to semiconducting behavior as the Mn level increases, at room temperature, ρ(T) exhibit values less than 4mΩ-cm. From S(T), ρ(T) and κ(T) data, the thermoelectric power factor and the figure of merit were determined. These performance parameters reach maximum values around 18 μW/K2-cm and 0.2, respectively. The observed behavior in the transport properties become these compounds potential thermoelectric materials, which could be used in thermoelectric applications.
Investigation of Composition-dependent Optical Phonon Modes in AlxGa1-xN Epitaxial Layers Grown on Sapphire Substrates
Authors: Chen Jun-Rong , Lu Tien-Chang , Kuo Hao-Chung , Wang Shing-Chung 
Published: June 2009

AbstractWe reported the systematical study of optical properties of hexagonal AlxGa1-xN epitaxial films grown on c-sapphire substrate using metal-organic chemical vapor deposition. By performing Fourier transform infrared spectroscopy measurements, the high-frequency dielectric constants and phonon frequencies can be obtained by theoretically fitting the experimental infrared reflectance spectra using a four-phase layered model. The high-frequency dielectric constant of AlxGa1-xN varies between 4.98 and 4.52 for ε∝,│(polarization perpendicular to the optical axis) and between 4.95 and 4.50 for ε∝,//(polarization parallel to the optical axis) respectively when the aluminum composition changes from 0.15 to 0.24. Furthermore, from experimental infrared reflectance spectra of AlxGa1-xN films, a specific absorption dip at 785 cm-1 was observed when the aluminum composition is larger than 0.24. The dip intensity increases and the dip frequency shifts from 785 to 812 cm-1 as aluminum composition increases from 0.24 to 0.58. According to the reciprocal space map of x-ray diffraction measurements, the emergence of this dip could be resulted from the effects of strain relaxation in AlGaN epitaxial layers due to the large lattice mismatch between GaN and AlGaN epitaxial film.
Evolution of Textural, Structural and Morphological Properties of Ag/TiO2 Nanocomposites Tailored by Temperature
Authors: Viana Marcelo , Mohallem Nelcy Della Santina 
Published: June 2009

AbstractTiO2 is a promising material for use in environmental purification due to its strong oxidizing power, photoinduced hydrophilicity, non-toxicity and long-term photostability. Nanocomposites formed by silver dispersed in titania matrix have their application quality improved since silver particles can act in the electronic structure of the titania. In this work, titanium isopropoxide and silver nitrate solution was used as starting of Ag/TiO2 nanocomposites. After irradiation and gelification at room temperature, this material was dried and calcined at various temperatures up to 1100 °C. The nanocomposites were characterized to investigate the structural evolution of the nanoparticles and the dependence of crystallite size with the calcination temperature.
Characterization of ZnO Nanostructures Grown by Pulsed Laser Deposition
Authors: Weigand Christian , Bergren Matthew R , Ladam Cecile , Vullum Per Erik , Walmsley John C , Fagerberg Ragnar , Furtak Tom E , Collins Reuben , Grepstad Jostein , Weman Helge 
Published: June 2009

AbstractZnO nanostructures were grown by pulsed laser deposition on c-plane sapphire substrates. The as-grown nanostructures were examined by scanning electron microscopy and transmission electron microscopy ZnO nanowires were grown using a gold catalyst, at a high substrate temperature of 800°C and an ambient gas pressure of 0.5 mbar (5% oxygen, 95% argon). Changing the gas composition to pure oxygen led to the growth of stacking fault-free ZnO nanosheets with their growth direction inclined to the [0001] direction. Similar nanosheets with stacking faults were found when lowering the growth temperature to 600°C for a 5% oxygen – 95% argon ambient gas composition and the same overall pressure. A growth mechanism for these ZnO nanosheets is proposed.
Structural and Ferromagnetic Properties of Fe3Si Thin Films Sputter-Deposited on Si(001)
Authors: LIEW Siao Li , SENG Debbie Hwee Leng , TAN Hui Ru , CHI Dongzhi 
Published: June 2009

AbstractFe3Si thin films were deposited on Si(001) from magnetron sputtering with varying deposition rates and subjected to post-deposition anneal (PDA). Structural investigations via XRD, SIMS and cross-sectional TEM reveal that high rate-deposited Fe3Si is amorphous while low rate-deposited Fe3Si is poly-crystalline with significant differences observed at the Fe3Si/Si interfaces. The structural differences were attributed to the influence of deposition rate on the grain nucleation and microstructural morphology in the as-deposited Fe3Si and the subsequent annealed films which in turn determine the ferromagnetic properties. Magnetic properties of Fe3Si deposited at high rate degrade with PDA - coercive field Hc increases from 1 to 14 Oe while saturation magnetization Ms decreases from ˜940 to 590 emu/cm3. In contrast, Fe3Si film sputter-deposited at low rate has a Hc of 5 Oe, Ms of ˜920 emu/cm3 and remnant magnetization Mr ˜0.9Ms that are maintained even upon PDA at 350 oC.
Solving Unknown Complex Oxide Structures by Precession Electron Diffraction: AgCoO2, PbMnO2.75 and LiTi1.5Ni0.5O4
Authors: Klein Holger , Gemmi Mauro , Rageau Amélie 
Published: June 2009

AbstractOxides synthesized in high temperature / high pressure conditions often show complex structures and contain several phases which makes a structure solution by X-ray crystallography very difficult or even impossible. Electron crystallography can then be a powerful alternative. We show here the structure solution of 3 oxides by precession electron diffraction. The phases include a simple hexagonal structure (AgCoO2), a complex monoclinic structure (PbMnO2.75) with a quasi 2-dimensional unit cell and a complex trigonal structure (LiTi1.5Ni0.5O4). In the last case even the positions for the light element Li were determined.
Parametric Studies on the Processing Parameters of a Thermally Wicking Material using Image Analysis
Authors: Lin Stephanie J. , Nadler Jason H. 
Published: June 2009

AbstractA heat pipe is a device that transports heat against gravity using a wicking material and evaporation-condensation cycle..In these systems a thermal wick moves fluid from the cool region of a heat pipe to the hot region, where evaporative cooling occurs. Due to the operating demands of a thermal wick, several microstructural features are integral to the performance of the wick: capillary radii, specific surface area and permeability. Measuring these properties of a thermal wick (capillary radii, specific surface area and permeability) is difficult, therefore image analysis methods of quantification of the critical properties of a thermal wick has been developed . However, the microstructure of a thermal wick contains semicontinuous pores, therefore connectivity of pores cannot be assumed during quantification of the critical properties.. Two processing parameters, sacrificial template particle size and sintering temperature, were varied during the thermal wick synthesis. Quantification of the critical properties of the thermal wick was performed using the newly developed method. The newly developed method was able to detect the an increase in the pore connectivity as the sintering temperature decreased, and an increase in the connectivity as the sacrificial template particle size decreased. The newly developed method was also able to describe the size distribution of individual pores as well as the hydraulic resistance and orientation of individual pores as well as estimate the porosity and true specific surface area of the different samples.
Fabrication of Microfluidic Devices for Droplet Generation based on Dry Film Resist
Authors: Leech Patrick William , Wu Nan , Zhu Yonggang 
Published: June 2009

AbstractDry film resist has been used in the fabrication of Masters in microfluidic devices for droplet generation. The minimum feature size in the resist was controlled by the type of mask (transparency or electron beam Cr mask), the resolution of the pattern in transparency masks (2400 or 5080 dpi) and thickness of resist in the range from 35 to 140 μm. The Master patterns formed in dry resist were replicated as a Ni shim and then hot embossed into Plexiglas 99524. These devices were used to generate water-in-oil droplets with a well defined dependence of diameter and frequency on flow parameters. The application of dry laminar resist and transparency masks has allowed the rapid fabrication of prototype devices.
PDA Usage by Japanese Resident Physicians Is Low
Authors: Takahashi O. , Ohde S. , Tokuda Y. , Omata F. , Fukui T. , Jacobs J. L. 
Published: June 2009

Summary
Objectives: Personal digital assistants (PDAs) are in widespread use by resident physicians in many countries, reaching as high as 95% in some reports. Uses are varied and include clinical decision support and support of evidence-based practice. Utilization by resident doctors in Japan has not been characterized. This study was conducted to determine practice patterns of PDA use by Japanese resident physicians.
Methods: A nationwide cohort survey study was distributed to all 1070 residency teaching programs in Japan. The survey included questions pertaining to use of PDAs in clinical practice.
Results: 1124 surveys were returned (response rate of approximately 75%). 297 (30.7%) respondents reported currently using PDAs, while 971 (86.4%) reported having used a PDA in the past. PDA users were more likely to be male (p < 0.05), but no other significant differences were found when examining the following variables: age, training site (university hospital versus community teaching hospital), satisfaction with existing information technology access.
Conclusions: Use of PDAs among Japanese resident physicians is much lower than their counterparts in other countries. In light of this, further research on patient outcomes in Japan and the impact of PDA usage on patient outcomes is urgently needed. If demonstrated to improve outcomes, barriers to adoption need to be identified and overcome.
3D Segmentation of the Left Ventricle Combining Long- and Short-axis MR Images
Authors: Relan J. , Groth M. , Müllerleile K. , Handels H. , Säring D. 
Published: June 2009

Summary
Objectives: Segmentation of the left ventricle (LV) is required to quantify LV remodeling after myocardial infarction. Therefore spatiotemporal cine MR sequences including long-axis and short-axis images are acquired. In this paper a new segmentation method for fast and robust segmentation of the left ventricle is presented.
Methods: The new approach considers the position of the mitral valve and the apex as well as the long-axis contours to generate a 3D LV surface model. The segmentation result can be checked and adjusted in the short-axis images. Finally quantitative parameters were extracted.
Results: For evaluation the LV was segmented in eight datasets of the same subject by two medical experts using a contour drawing tool and the new segmentation tool. The results of both methods were compared concerning interaction time and intra- and inter-observer variance. The presented segmentation method proved to be fast. The mean difference and standard deviation of all parameters are decreased. In case of intra-observer comparison e.g. the mean ESV difference is reduced from 8.8% to 0.5%.
Conclusion: A semi-automatic LV segmentation method has been developed that combines long- and short-axis views. Using the presented approach the intra- and inter-observer difference as well as the time for the segmentation process are decreased. So the semi-automatic segmentation using long-and short-axis information proved to be fast and robust for the quantification of LV mass and volume properties.
Sexually dimorphic effect of the Val66Met polymorphism of BDNF on susceptibility to Alzheimer's disease: New data and meta‐analysis
Authors: Fukumoto Noriko , Fujii Takashi , Combarros Onofre , Kamboh M. Ilyas , Tsai Shin‐Jen , Matsushita Sachio , Nacmias Benedetta , Comings David E. , Arboleda Humberto , Ingelsson Martin , Hyman Bradley T. , Akatsu Hiroyasu , Grupe Andrew , Nishimura Agnes Lumi , Zatz Mayana , Mattila Kari M. , Rinne Juha , Goto Yu‐ichi , Asada Takashi , Nakamura Shun , Kunugi Hiroshi 
Published: June 2009

AbstractConflicting results have been reported as to whether genetic variations (Val66Met and C270T) of the brain‐derived neurotrophic factor gene (BDNF) confer susceptibility to Alzheimer's disease (AD). We genotyped these polymorphisms in a Japanese sample of 657 patients with AD and 525 controls, and obtained weak evidence of association for Val66Met (P = 0.063), but not for C270T. After stratification by sex, we found a significant allelic association between Val66Met and AD in women (P = 0.017), but not in men. To confirm these observations, we collected genotyping data for each sex from 16 research centers worldwide (4,711 patients and 4,537 controls in total). The meta‐analysis revealed that there was a clear sex difference in the allelic association; the Met66 allele confers susceptibility to AD in women (odds ratio = 1.14, 95% CI 1.05–1.24, P = 0.002), but not in men. Our results provide evidence that the Met66 allele of BDNF has a sexually dimorphic effect on susceptibility to AD. © 2009 Wiley‐Liss, Inc.
Ion Pairing and Salt Structure in Organic Salts through Diffusion, Overhauser, DFT and X‐ray Methods
Authors: Moreno Aitor , Pregosin Paul S. , Veiros Luis F. , Albinati Alberto , Rizzato Silvia 
Published: June 2009

AbstractPulsed gradient spin‐echo (PGSE) diffusion characteristics for a) the new [brucinium][X] salts 6 a–f [a: X=BF4−; b: X=PF6−; c: X=MeSO3−, d: X=CF3SO3−; e: X=BArF−; f: X=PtCl3(C2H4)−], b) 4‐tert‐butyl‐N‐benzyl analogue, 7 and c) the aryl carbocations (p‐R‐C6H4)2CH 9 a (R=CH3O) and 9 b (R=(CH3)2N), (p‐CH3O‐C6H4)xCPh3−x+ 10 a–c (x=1–3, respectively) and (p‐R‐C6H4)3C+ 11 (R=(CH3)2N) and 12 (R=H) all in several different solvents, are reported. The solvent dependence suggests strong ion pairing in CDCl3, intermediate ion pairing in CD2Cl2 and little ion pairing in [D6]acetone. 1H, 19F HOESY NMR spectra (HOESY: heteronuclear Overhauser effect spectroscopy) for 6 and 7 reveal a specific approach of the anion with respect to the brucinium cation plus subtle changes, which are related to the anion itself. Further, for carbocations 9–12, (all as BF4− salts) based on the NOE results, one finds marked changes in the relative positions of the BF4− anion. In these aryl cationic species the anion can be located either a) very close to the carbonium ion carbon b) in an intermediate position or c) proximate to the N or O atom of the p‐substituent and remote from the formally positive C atom. This represents the first example of such a positional dependence of an anion on the structure of the carbocation. DFT calculations support the experimental HOESY results. The solid‐state structures for 6 c and the novel Zeise's salt derivative, [brucinium][PtCl3(C2H4)], 6 f, are reported. Analysis of 195Pt NMR and other NMR measurements suggest that the η2‐C2H4 bonding to the platinum centre in 6 f is very similar to that found in K[PtCl3(C2H4)]. Field dependent T1 measurements on [brucinium][PtCl3(C2H4)] and K[PtCl3(C2H4)], are reported and suggested to be useful in recognizing aggregation effects.
Double Aromaticity and Ring Currents in All‐Carbon Rings
Authors: Fowler Patrick W. , Mizoguchi Noriyuki , Bean David E. , Havenith Remco W. A. 
Published: June 2009

AbstractDouble aromaticity of neutral, planar rings of carbon atoms is demonstrated through visualisation of the induced ring currents, mapped at the ipsocentric B3LYP/6‐31G(d)//B3LYP/6‐31G(d) level for species C6 to C30, with onset of delocalised current in the in‐plane π system at C10/C11. Both in‐plane and conventional out‐of‐plane π systems have diatropic/paratropic current in accordance with the Hückel rule, with 4 m+2 occupation of the out‐of‐plane π system taking precedence, as predicted by simple nesting of Frost–Musulin diagrams. The current‐density maps show characteristic double‐doughnut and double‐track topographies for out‐of‐plane and in‐plane ring currents, respectively, both governed by a common framework of angular momentum rules.
DCE‐MRI in experimental chronic pancreatitis
Authors: Shu Jian , Zhang Xiao Ming , Zhao Jian Nong , Yang Lin , Zeng Nan Ling , Zhai Zhao Hua 
Published: June 2009

AbstractTo assess pancreatic perfusion in experimental chronic pancreatitis (CP) by dynamic contrast‐enhanced (DCE) magnetic resonance imaging (MRI). DCE MRI on a 1.5 T MR scanner was performed on 21 piglets with the ligation of pancreatic duct. They were divided into four groups based on pathology, including seven normal pigs and seven, three and four piglets with grade I, II and III CP, respectively. The signal intensity measured in the pancreatic body on DCE MRI was plotted against time to create a signal intensity–time (SI–T) curve for each piglet. The steepest slope (SS), time‐to‐peak (TTP) and peak enhancement ratio (PER) of the SI–T curve were noted. In the four groups, on the SI–T curve derived from DCE MRI, the SS was, respectively, 10.88 ± 1.20, 10.59 ± 1.02, 6.67 ± 1.31 and 5.48 ± 1.97%/s (F = 20.509, p = 0.000) from normal piglets to piglets with grade III CP. The TTP was 13.82 ± 3.09, 12.31 ± 5.52, 20.55 ± 3.79 and 37.26 ± 14.56 s (F = 10.681, p = 0.000) and the PER was 62.95 ± 20.20, 60.44 ± 20.00, 46.33 ± 22.70 and 67.65 ± 32.66% (F = 0.529, p = 0.668), respectively. The SS (r = –0.719, p = 0.000) and TTP (r = 0.538, p = 0.012) of the SI–T curve was correlated to the severity of CP, respectively. DCE MRI has a potential to diagnose moderate to advanced CP. The SS and TTP of the SI–T curve were correlated to the severity of CP. Copyright © 2009 John Wiley & Sons, Ltd.
X‐ray Absorption Spectroscopy as a Probe of Photo‐ and Thermally Induced Valence Tautomeric Transition in a 1:1 Cobalt–Dioxolene Complex
Authors: Poneti Giordano , Mannini Matteo , Sorace Lorenzo , Sainctavit Philippe , Arrio Marie‐Anne , Rogalev Andrei , Wilhelm Fabrice , Dei Andrea 
Published: June 2009

AbstractThe role of the cobalt ion in the entropy‐ and optically‐driven valence tautomeric (VT) interconversion exhibited by the [Co(Me2tpa)(DTBdiox)](PF6)⋅C6H5CH3 complex (Me2tpa=bis (6‐methyl‐(2‐pyridylmethyl))(2‐pyridylmethyl)amine, DBdiox=3,5‐ditertbutyl‐dioxolene) is established by means of X‐ray absorption spectroscopy (XAS). Analysis of the pre‐edge features at 6 and 300 K in the Co K‐edge XAS spectra using a ligand field multiplet approach allows us to obtain detailed information on the electronic structures of the metal ion in the two redox isomers. The temperature dependence of the spectra confirms the occurrence of a thermally induced VT transition and suggests that nucleation and distortion of the phase boundaries take place during the process. Moreover, optically induced metastable state formation is monitored at low temperatures—with a high degree of reproducibility—without changing the position of measurement on the sample during the experiment. This result paves the way for the use of such a highly sensitive technique for the investigation of photoswitchable materials in non‐crystalline and nanostructured environments.
Early lens development in the zebrafish: A three‐dimensional time‐lapse analysis
Authors: Greiling Teri M.S. , Clark John I. 
Published: June 2009

AbstractIn vivo, high‐resolution, time‐lapse imaging characterized lens development in the zebrafish from 16 to 96 hr postfertilization (hpf). In zebrafish, the lens placode appeared in the head ectoderm, similar to mammals. Delamination of the surface ectoderm resulted in the formation of the lens mass, which progressed to a solid sphere of cells separating from the developing cornea at approximately 24 hpf. A lens vesicle was not observed and apoptosis was not a major factor in separation of the lens from the future cornea. Differentiation of primary fibers began in the lens mass followed by formation of the anterior epithelium after delamination was complete. Secondary fibers differentiated from elongating epithelial cells near the posterior pole. Quantification characterized three stages of lens growth. The study confirmed the advantages of live‐cell imaging for three‐dimensional quantitative structural characterization of the mechanism(s) responsible for cell differentiation in formation of a transparent, symmetric, and refractile lens. Developmental Dynamics 238:2254–2265, 2009. © 2009 Wiley‐Liss, Inc.
Thermodynamic and Structural Investigations on the Complexation Process of Dioxo Macrocyclic Ligands: Towards Neutral Copper Complexes at Physiological pH
Authors: Déchamps‐Olivier Isabelle , Cadiou Cyril , Harakat Dominique , Roisnel Thierry , Chuburu Françoise , Hodacova Jana , Koscova Simona 
Published: June 2009

AbstractTwo dioxotetraza macrocycles 9,12,16,19‐tetraazatricyclo[19.4.0.02,7]pentacosa‐1(21),2,4,6,22,24‐hexaene‐8,20‐dione(L1) and 9,13,16,20‐tetraazatricyclo[20.4.0.02,7]hexacosa‐1(22),2,4,6,23,25‐hexaene‐8,21‐dione (L2) and two bis(dioxotetraaza) macrocycles 7,10,14,17,25,28,32,35‐octaazatetracyclo[17.17.2.05,37.023,38]octatriaconta‐1,3,5(37),19,21,23(38)‐hexaene‐6,18,24,36‐tetrone (L3) and 7,11,14,18,26,30,33,37‐octaazatetracyclo[18.18.2.05,39.024,40]tetraconta‐1,3,5(39),20,22,24(40)‐hexaene‐6,19,25,38‐tetrone (L4) were prepared. Their protonation constants and the overall complexation constants of their copper(II) complexes were determined by potentiometry at 25 °C (I = 1, KNO3). In aqueous solution, the complexation sequence was elucidated for each ligand by means of UV/Vis and EPR spectroscopy. According to the ligand structure, two complexation mechanisms can be characterized. For ligand L1, a neutral complex [CuL1H–2] is readily obtained in one step at pH ≈ 5, and it is the sole species above pH 7. Its structure was confirmed by X‐ray analysis. For ligands L2 and L4, the neutral complexes [CuL2H–2] and [Cu2L4H–4] were formed by successive deprotonation of [CuL2]2+ and [Cu2L4]4+, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)