bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural defects in homoepitaxial diamond layers grown on off‐axis Ib HPHT substrates
Authors: Bauer T. , Schreck M. , Härtwig J. , Liu X. H. , Wong S. P. , Stritzker B. 
Published: September 2006

AbstractIn the present study homoepitaxial diamond films have been grown by microwave plasma chemical vapour deposition (MWPCVD) on (001)‐oriented Ib HPHT substrates with off‐axis angles of up to 11°. Freestanding films of several hundred microns thickness were produced by removal of the Ib substrate and of the polycrystalline rim. In high resolution X‐ray diffraction (HRXRD) rocking curve measurements the crystals showed a full width at half maximum (FWHM) between (2 × 10–3)°, which is close to the instrumental limit of our setup, and maximum values of (3 × 10–2)°. The structural quality is directly reflected in the strength of the birefringence observed in the optical microscope. While the high quality sample showed a weak birefringence with a couple of localized centres distributed over the whole sample surface, a tatami‐like pattern is measured for the sample with the broad rocking curve. Identical defect structures with perfect correspondence are observed in X‐ray topography images. Furthermore the X‐ray topographs allow to identify isolated dislocation lines. Both characterisation methods show that the defect lines are aligned along the off‐axis direction which allows conclusions on the mechanism of formation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanocarbon field emission devices
Authors: Subramanian K. , Wong Y. M. , Kang W. P. , Davidson J. L. , Choi B. K. , Howell M. 
Published: September 2006

AbstractWe are fabricating and examining nanocarbon derived electron emission devices, specifically, nanodiamond lateral field emission diodes and gated carbon nanotube triodes. These novel microstructures provide interesting means of accomplishing electronics that are unaffected by temperature and radiation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
All optical read‐out radiation dosimeter using CVD synthetic diamond
Authors: Preciado‐Flores S. , Schreck M. , Meléndrez R. , Chernov V. , Pedroza‐Montero M. , Barboza‐Flores M. 
Published: September 2006

AbstractIn the present work, we evaluate the optically stimulated luminescence (OSL) dosimetric properties of two polycrystalline 10 μm thick films, undoped and 750 ppm nitrogen doped, grown on (100) silicon substrates exposed to beta radiation. The samples were optically stimulated to free and to induce radiative recombination of the trapped charges caused by radiation absorption. This all optical technique uses IR laser 830 nm light for stimulation and a PMT coupled to a BG‐39 (300–600 nm) filter for light intensity measurements. The OSL of both samples is very similar in output intensity and hyperbolic decay type. The OSL signal of non doped samples involves localized trapping states around the 373–653 K as compared to nitrogen doped sample which involves the charge detrapping of localized states in the 353–550 K range. The OSL signal in the first 0.16 s shows two linearity regions for 0–35 Gy and 35–100 Gy dose ranges. An obvious advantage of OSL over TL/TSC methods is that no heating is required, it may also open the possibility of using CVD diamond coupled to optical fibers for stimulation and read‐out light signals allowing in situ and real time dose measurements. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
HR‐TEM imaging and image simulation of vacancy clusters in brown diamond
Authors: Barnes R. , Bangert U. , Martineau P. 
Published: September 2006

AbstractDiamonds, although famous for their sparkling colourless nature, can exhibit many colours due to imperfections in the crystal lattice. Brown diamonds, while not the favourite variety, have attracted much attention and mystery in finding the origin of the colour. The defect, which is not impurity related, can be removed with HPHT treatment. Collections of vacancies have been suggested as the source of the colour by theoretical calculations [1] and positron annihilation experiments [2, 3]. Therefore, simulations have been carried out to determine whether the suggested sizes of vacancy clusters could be seen in HR‐TEM. Substantial contrast has been revealed in defocused images. In light of the simulations, experimental defocus series have been acquired in lattice resolution for brown and colourless, natural and synthetic type IIa diamonds. A small‐scale patchiness is apparent in the lattice images of brown but not of colourless diamond. Further analysis, including simulations of multiple vacancy clusters, suggests this contrast in brown diamond could be due to many irregularly distributed vacancy clusters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
N‐type doped nano‐diamond in a first MEMS application
Authors: Dipalo M. , Kusterer J. , Janischowsky K. , Kohn E. 
Published: September 2006

AbstractNanocrystalline diamond is an interesting material for MEMS applications especially due to its outstanding mechanical, electrical and electrochemical properties. The current choice for doping is boron, resulting in p‐type conduction. It has two difficulties: firstly, at high concentration (as needed for full activation) the lattice becomes highly stressed and may degrade the material's quality. Secondly, it contaminates the growth chamber, resulting in a memory effect. A recent alternative is n‐type nitrogen doping, avoiding these disadvantages. However, nitrogen is mainly incorporated in the grain boundaries and thus inhomogeneously distributed. In turn this may limit the material's stability. Here we present a first trial to use nitrogen‐doped nanocrystalline diamond (NCD), grown by hot filament CVD, in a water microjet as heater element. No stability problems were encountered even at high overdrive power. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characteristics of n‐type diamond Schottky diodes and metal/diamond interfaces
Authors: Suzuki Mariko , Koizumi Satoshi , Katagiri Masayuki , Ono Tomio , Sakuma Naoshi , Yoshida Hiroaki , Sakai Tadashi , Uchikoga Shuichi 
Published: September 2006

AbstractElectrical characteristics of n‐type diamond Schottky diodes and metal/diamond interfaces have been systematically investigated for phosphorus (P)‐doped homoepitaxial diamond layers. The current–voltage (I–V) characteristics of the Ni/n‐type diamond Schottky diode show excellent rectification properties from 297 K to 773 K. The ideality factor and the rectification ratio were 1.0 and ∼106 at +10 V at 573 K, respectively. The rectifying properties deteriorated with increasing P concentration in the diamond layers. Temperature‐dependent capacitance–frequency (C–f) and conductance–frequency (G–f) measurements on the Schottky diodes have shown that the capacitance is reduced at high frequency due to the inability of deep centers to maintain an equilibrium ionization state under a high‐frequency modulation. C–V measurements deduced that the P electrical activity (the ratio of the net donor concentration to the P concentration) was nearly 1 from low concentration (1.6 × 1016cm–3) to high concentration (2.7 × 1018cm–3) of P. The Schottky barrier height was found to be almost constant at ∼4.3 eV independent of the metal work function (Ni, Pt, Al and Ti). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Compositional and electrical characterisation of the hydrogen–oxygen terminated diamond (100) surface
Authors: Deferme W. , Haenen K. , Tanasa G. , Flipse C. F. J. , Nesládek M. 
Published: September 2006

AbstractIn this work (100) diamond films are hydrogenated using a conventional MWPE‐CVD (microwave plasma enhanced chemical vapour deposition) reactor containing a H2 or a H2/O2 mixture. For the latter, XPS (X‐ray Photoelectron Spectroscopy) experiments show an increased presence of oxygen at the (sub)‐surface. Contrary to pure H2‐plasma treated samples, H2/O2‐treated layers still posses enough conductivity to enable STS (Scanning Tunneling Spectroscopy) investigations to be carried out after an annealing at 410 °C in UHV (Ultra High Vacuum). Evidence for surface resonance states is detected, yielding a possible explanation for the measured conductivity. UPS (UV Photoelectron Spectroscopy) data point to a negative electron affinity of –0.3 eV for the H2/O2‐treated layers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of single‐crystal CVD‐diamond detectors for spectroscopy and timing
Authors: Pomorski M. , Berdermann E. , Caragheorgheopol A. , Ciobanu M. , Kiš M. , Martemiyanov A. , Nebel C. , Moritz P. 
Published: September 2006

AbstractCharge‐transport parameters measured for several single‐crystal CVD‐diamond films are discussed as well as the consequences for the energy‐ and the time resolution of charged‐particle detectors made of these samples. Applying a transient‐current technique, where 241Am α‐particles are used for e–h pair creation, low‐field electron mobility values varying in the range 1300 < µ 0–e [cm2/Vs] < 3100 are obtained, and a common saturation velocity around v sat–e ≈ 1.9 × 107 [cm/s]. Hole data show impressive uniformity with µ 0–h ≈ 2330 [cm2/Vs] and v sat–h ≈ 1.4 × 107 [cm/s]. At detector operation bias (0.3 V/μm < E D < 3 V/μm) the holes drift systematically faster than the electrons. The lifetime of the charge carriers in best samples amounts to τ h ≈ 1 µs for holes and to τ e ∼ 320 ns for electrons. Comparable to the energy resolution of commercial silicon detectors, a ΔE = 17 keV (FWHM) is measured for 5.5 MeV α‐particles and ΔE /E ∼ 1% for heavy ions. Tests of single‐ and polycrystalline detectors with relativistic 27Al ions of 2 AGeV reveal the same intrinsic time resolution of σ (Δt) = 28 ps indicating limitations due to electronic noise. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thick single crystal CVD diamond prepared from CH4‐rich mixtures
Authors: Bogdan G. , De Corte K. , Deferme W. , Haenen K. , Nesládek M. 
Published: September 2006

AbstractRecent interests in freestanding single‐crystal CVD diamond (SC‐CVD) discs for several applications in electronics led to an intense study of SC‐CVD layer growth and properties. In this work we have investigated the growth mechanism of monocrystalline CVD diamond films with surfaces smooth in nanometer scale taking into account the defect incorporation in the SC‐CVD layers. Specifically we discuss the surface structure characteristics for these conditions as studied with high‐resolution AFM mapping. The as‐grown CVD layers were removed from the substrate by laser cutting, followed by a polishing step, yielding freestanding plates. Subsequently, microscopic and colour studies as well as infrared absorption spectroscopy were performed. These investigations revealed the presence of several characteristic defects and impurities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dislocation distributions in brown diamond
Authors: Willems B. , Martineau P. M. , Fisher D. , Van Royen J. , Van Tendeloo G. 
Published: September 2006

AbstractDislocation distributions are characterized on a µm‐scale in various plastically deformed natural brown type IIa diamond samples before and after high‐pressure high‐temperature (HPHT) treatment. Transmission electron microscopy (TEM) is used for a statistical study. Applying conventional diffraction contrast imaging, different parameters such as the total dislocation line density, the distribution of 〈101〉 and 〈112〉 line densities, and Burgers vectors of dislocations have been systematically determined for diamond samples before and after HPHT treatment. The total dislocation line density is about 109 cm–2, and does not change upon HPHT treatment. A significant proportion of the dislocations have 〈112〉 line directions besides the 〈101〉 line directions. No changes in dislocation distributions before and after HPHT‐treatment are reported so far. However, the presence of many paired 〈112〉 dislocations and small dislocation loops suggest a link to the current brown colour mechanism involving vacancy clusters or disks. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preface: phys. stat. sol. (a) 203/12
Authors: Jackman Richard B. , Nesládek Miloš , Haenen Ken 
Published: September 2006

AbstractThe 30 papers gathered in this issue of physica status solidi (a) give a thorough overview over different topics that were presented during the 11th edition of the International Workshop on Surface and Bulk Defects in CVD Diamond Films (SBDD), which took place from 22 to 24 February 2006, at the Hasselt University in Diepenbeek–Hasselt, Belgium. Since its start more than 10 years ago, the SBDD Workshop has grown into a well‐established, yearly “early bird” meeting place, addressing new emerging science related to the progress in the CVD diamond field. The 10 invited lectures, 29 contributed oral presentations and 26 posters were presented in several sessions during an intense two and a half day long meeting.The number of participants reached 115 this year with participants coming from fifteen countries: Austria, Belgium, Czech Republic, France, Germany, Israel, Italy, Japan, Mexico, Poland, Russia, Singapore, Slovak Republic, Sweden, UK, and USA. The mixture of young and established scientists, including a great proportion of students, made this meeting a hot spot of lively discussions on a wide range of scientific subjects, not only during the meeting itself, but also at several occasions throughout many social events offered by the hospitality of the city of Hasselt.It stands for itself that the workshop would not have been possible without the support of many people and institutions. For financial aid we are especially indebted to the Scientific Research Community “Surface Modification of Materials” of the F.W.O.‐Vlaanderen (Belgium), whose incessant support plays an important role in keeping this meeting going. We also thank the Hasselt University for offering the lecture hall and infrastructure facilities and Seki Technotron Corp. for sponsoring the poster reception and their presence with a table top exhibit. Finally we highly appreciate the active approach of the editorial staff of physica status solidi in this conference and would like to thank most notably Stefan Hildebrandt, Ron Schulz‐Rheinländer, Christoph Lellig, and Julia Hübner, for their excellent and patient work, bringing the number of successfully published proceedings of SBDD in pss (a) up to 8 already!To finish, we would all like to invite you to the 12th edition of the SBDD series, newly renamed as “Hasselt Diamond Workshop”, to be held at its established location of Diepenbeek–Hasselt. We look forward meeting you again at SBDD XII in 2007:Hasselt Diamond Workshop – SBDD XII28 February–2 March 2007Hasselt University, Diepenbeek–Hasselt, Belgiumhttp://www.imo.uhasselt.be/SBDD2007London, Paris, Hasselt, August 2006
Multi‐bit storage in reset process of Phase Change Access Memory (PRAM)
Authors: Zhang Yi , Feng Jie , Zhang Yin , Zhang Zufa , Lin Yinyin , Tang Ting'ao , Cai Bingchu , Chen Bomy 
Published: September 2006

AbstractA Phase Change Access Memory (PRAM) cell with stacked phase‐change layers and heater layers is prepared. Multi‐bit storage in the reset process of the PRAM is realized by this stacked structure including phase‐change layers with uniform thickness and heater layers with different thickness. The thermal simulation results show three phase‐change layers in three temperature zones, and they will transform from polycrystalline to amorphous state layer by layer. There are four levels of resistance appearing in theR–Vcharacteristics, and 2‐bit storage is realized. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Impact of the Built Environment on Children's School Conduct Grades: The Role of Diversity of Use in a Hispanic Neighborhood
Authors: Szapocznik José , Lombard Joanna , Martinez Frank , Mason Craig A. , Gorman-Smith Deborah , Plater-Zyberk Elizabeth , Brown Scott C. , Spokane Arnold 
Published: September 2006

AbstractA population‐based study examined the relationship between diversity of use of the built environment and teacher reports of children's grades. Diversity of use of the built environment (i.e., proportion of a block that is residential, institutional, commercial and vacant) was assessed for all 403 city blocks in East Little Havana, Miami—a Hispanic neighborhood. Cluster analysis identified three block‐types, based on diversity of use: Residential, Mixed‐Use, and Commercial. Cross‐classified hierarchical linear modeling was used to examine the impact of diversity of use, school, gender, and year‐in‐school on academic and conduct grades for 2857 public school children who lived in these blocks. Contrary to popular belief, mixed‐use blocks were associated with optimal outcomes. Specifically, follow‐up analyses found that a youth living on a residential block had a 74% greater odds of being in the lowest 10% of conduct grades (conduct GPA <2.17) than a youth living on a mixed‐use block. In fact, an analysis of the population attributable fraction suggests that if the risk associated with residential blocks could be reduced to the level of risk associated with mixed‐use blocks, a 38% reduction in Conduct GPAs <2.17 could be achieved in the total population. These findings suggest that public policy targeting the built environment may be a mechanism for community‐based interventions to enhance children's classroom conduct, and potentially related sequelae.
Activation of Rac1 by Rho‐guanine nucleotide dissociation inhibitor‐β with defective isoprenyl‐binding pocket
Authors: Ota Takahide , Maeda Masayo , Murakami Manabu , Takegami Tsutomu , Suto Shiho , Tatsuka Masaaki 
Published: September 2006

AbstractRho‐guanine nucleotide dissociation inhibitor‐β (RhoGDIβ), a regulator for Rho GTPases, is implicated in cancer cell progression. We reported that C‐terminal truncated RhoGDIβ (ΔC(166–201)‐RhoGDIβ) promoted metastasis through activating Rac1 signaling pathway in ras‐transformed fibroblast cells. To better understand the mechanism of Rac1 activation by ΔC(166–201)‐RhoGDIβ during metastasis, the amount of GTP‐bound Rac1 was measured as the activation level of Rac1 in cells expressing various mutant RhoGDIβ with sequential C‐terminal deletions. Three C‐terminal hydrophobic amino acid residues (Trp191, Leu193, and Ile195) supposed to interact with isoprenyl groups of Rac1, was indispensable for a proper regulation of Rac1 activation/inhibition. Deletion of this region led RhoGDIβ to continuously associate with GTP‐bound Rac1, provoking constitutive activation of Rac1. Thus, impaired interaction of RhoGDIβ with Rac1 isoprenyl groups possibly makes RhoGDIβ function as a positive regulator for Rac1 during metastasis.
Establishment and characterization of SV40 large T antigen‐immortalized cell lines derived from fetal bovine brain tissues after prolonged cryopreservation
Authors: Takenouchi Takato , Iwamaru Yoshifumi , Sato Mitsuru , Yokoyama Takashi , Shinagawa Morikazu , Kitani Hiroshi 
Published: September 2006

AbstractBovine brain cell lines with specific characteristics are usefulin vitroexperimental systems for molecular and cellular investigation of the interactions between bovine specific neuropathogenic agents and the host. Here, we established two novel cell lines from cultures of cryopreserved fetal bovine brain tissue by the transfection of SV40 large T antigen. Both cell lines showed cobblestone morphology in DMEM/F12 medium supplemented with 10% fetal bovine serum, epidermal growth factor and basic fibroblast growth factor. They were immunostained with endothelial marker, Von Willebrand Factor. Endothelial properties, such as capillary‐like tube formation on matrigel and the incorporation of DiI‐AcLDL were confirmed with these cells. Removal of growth factors increased the number of cells expressing α‐smooth muscle actin, suggesting the potential of these cell lines to differentiate into smooth muscle cells. This study suggests an efficient protocol to immortalize brain endothelial cell lines from fetal bovine brain tissue culture.
Effects of pyrrophenone, an inhibitor of group IVA phospholipase A2, on eicosanoid and PAF biosynthesis in human neutrophils
Authors: Flamand N , Picard S , Lemieux L , Pouliot M , Bourgoin S G , Borgeat P 
Published: September 2006

Background and Purpose:The biosynthesis of leukotrienes (LT) and platelet‐activating factor (PAF) involves the release of their respective precursors, arachidonic acid (AA) and lyso‐PAF by the group IVA PLA2 (cPLA2α). This paper aims at characterizing the inhibitory properties of the cPLA2α inhibitor pyrrophenone on eicosanoids and PAF in human neutrophils (PMN).Experimental Approach:Freshly isolated human PMN were activated with physiological and pharmacological agents (fMLP, PAF, exogenous AA, A23187 and thapsigargin) in presence and absence of the cPLA2α inhibitor pyrrophenone and biosynthesis of LT, PAF, and PGE2 was measured.Key Results:Pyrrophenone potently inhibited LT, PGE2 and PAF biosynthesis in PMN with IC50s in the range of 1–20 nM. These inhibitory effects of pyrrophenone were specific (the consequence of substrate deprivation), as shown by the reversal of inhibition by exogenous AA and lyso‐PAF. Comparative assessment of pyrrophenone, methyl‐arachidonoyl‐fluoro‐phosphonate (MAFP) and arachidonoyl‐trifluoromethylketone (AACOCF3) demonstrated that pyrrophenone was more specific and 100‐fold more potent than MAFP and AACOCF3 for the inhibition of LT biosynthesis in A23187‐activated PMN. The inhibitory effect of pyrrophenone on LT biosynthesis was reversible as LT biosynthesis was recovered when pyrrophenone‐treated PMN were washed with autologous plasma. No alteration of phospholipase D (PLD) activity in fMLP‐activated PMN was observed with up to 10 μM pyrrophenone, suggesting that the cPLA2α inhibitor does not directly inhibit PLD.Conclusions and Implications:Pyrrophenone is a more potent and specific cPLA2α inhibitor than MAFP and AACOCF3 and represents an excellent pharmacological tool to investigate the biosynthesis and the biological roles of eicosanoids and PAF.British Journal of Pharmacology (2006) 149, 385–392. doi:10.1038/sj.bjp.0706879
Sustained contraction and loss of NO production in TGFβ1‐treated endothelial cells
Authors: Watanabe M , Oike M , Ohta Y , Nawata H , Ito Y 
Published: September 2006

Background and purpose:Transforming growth factor β1 (TGFβ1) is generated in atherosclerotic and injured vessel walls. We examined whether the endothelial‐to‐mesenchymal transdifferentiation induced by TGFβ1 affects endothelial functions.Experimental approach:Bovine aortic endothelial cells (BAECs) were treated with 3 ng ml−1 TGFβ1 for 7 days. Contraction of TGFβ1‐treated BAECs was assessed by collagen gel contraction assay. Protein expression and phosphorylation were assessed by Western blotting. Intracellular Ca2+ concentration and NO production were measured using fura2 and DAF‐2, respectively.Key results:TGFβ1‐treated BAECs showed dense actin fibers and expressed smooth muscle marker proteins; they also changed into smooth muscle‐like, spindle‐shaped cells in collagen gel cultures. ATP (10 μM) induced a gradual contraction of collagen gels containing TGFβ1‐treated BAECs but not of gels containing control BAECs. ATP‐induced contraction of TGFβ1‐treated BAECs was not reversed by the removal of ATP but was partially suppressed by a high concentration of sodium nitroprusside (1 μM). TGFβ1‐treated BAECs showed sustained phosphorylation of myosin light chain in response to ATP and low levels of basal MYPT1 expression. ATP‐induced Ca2+ transients as well as eNOS protein expression were not affected by TGFβ1 in BAECs. However, ATP‐induced NO production was significantly reduced in TGFβ1‐treated BAECs. Anti‐TGFβ1 antibody abolished all of these TGFβ1‐induced changes in BAECs.Conclusions and Implications:Mesenchymal transdifferentiation induced by TGFβ1 leads to sustained contraction and reduced NO production in endothelial cells. Such effects, therefore, would not be beneficial for vascular integrity.British Journal of Pharmacology (2006) 149, 355–364. doi:10.1038/sj.bjp.0706883