bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of frequency on fatigue threshold and crack propagation rate in modified and unmodified polyvinyl chloride
Authors: Samat Noorasikin , Burford Robert , Whittle Alan , Hoffman Mark 
Published: March 2009

AbstractThe cyclic fatigue crack behavior of polyvinyl chloride (PVC), with (PVC‐M) and without (PVC‐U) chlorinated polyethylene (CPE) impact modifier, was studied. The effect of impact modifier upon fatigue crack growth rate and threshold was evaluated at frequencies of 1, 7, and 20 Hz. It was shown that the addition of CPE lowered the threshold stress intensity factor amplitude for crack growth (ΔKth) of PVC‐M compared to that of PVC‐U at lower frequencies, and that the effect became more pronounced at lower frequency. At lower stress intensity factor amplitudes (below ΔK = 1 MPa·m1/2), there was a slight difference between the crack growth rates of U‐ and M‐PVC. The crack advance mechanism is investigated by microscopic observation of the crack tip process zone. Although the zone is relatively large in PVC‐M, associated with higher toughness, it did not improve the fatigue crack growth resistance significantly. Fracture surface observations reveal a higher density of fibrils on the fatigued surface of PVC‐M with the density, relative to that observed in PVC‐U, reducing with frequency. It is therefore hypothesized that accelerated fibril failure is a mechanism of fatigue. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
The effect of copper(II) on the thermal and mechanical properties of poly(vinyl alcohol)/silica hybrid
Authors: Li Juan , Suo Jinping , Wang Shifang 
Published: March 2009

AbstractA novel copper‐poly(vinyl alcohol) (PVA)/silica complex was prepared and its chemical structure, thermal, and mechanical properties were studied. The results showed that the crystallinity of PVA first increased and then decreased by the addition of copper chloride, whereas, the thermal decomposition temperature increased dramatically. For PVA/silica hybrid, the decomposition temperature associated with the removal of water molecules in PVA chains was 262°C. But the temperature increased to 361°C when the content of copper chloride was 2 wt%. The intelligent electronic tensile tester was used to investigate the mechanical properties of these complexes. The results suggested that the tensile strength of the complexes is improved with negligible decrease in the plasticity. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Dual‐type electrochromic device with single wall carbon nano tube employment in gel electrolyte
Authors: Kösemen Arif , San S. Eren , Yerli Yusuf , Okutan Mustafa , Uygun Melek , Yilmaz Faruk , Celik Asuman 
Published: March 2009

AbstractA novel conducting polymer‐based electrochromic device is proposed with single walled carbon nanotube (SWCNT) employment in gel electrolyte. Electrochemical film deposition on indium tin oxide substrates were governed and monitored via cyclic‐voltametry. Construction details of the proposed device are presented with its optimized parameters and SWCNT doping caused a noteworthy enhancement in efficiency and stability of the device performance. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Experimental and theoretical study on 3,5‐(oxo/thioxo) derivatives of 2,7‐dimethyl‐1,2,4‐triazepines–iodine molecular complexes
Authors: Esseffar M'Hamed , El Messaoudi Malika , Bouab Widad 
Published: March 2009

AbstractIntermolecular charge‐transfer (CT) spectra of 3‐thioxo‐5‐oxo‐, 5‐thioxo‐3‐oxo‐, and 3,5‐dithioxo‐ derivatives of 2,7‐dimethyl‐[1,2,4]‐triazepine 1:1 molecular complexes with molecular iodine were studied in the UV‐visible region. Equilibrium constants and free energy changes of the formed complexes were determined in solution. Ab initio calculations at HF/LANL2DZ* and MP2/LANL2DZ* were carried out to establish the nature of the complexation site, to determine the complex structures, and to examine the basicity of these compounds toward molecular iodine. The 3,5‐dithioxo‐2,7‐dimethyl‐[1,2,4]‐triazepine is the most basic one toward molecular iodine. In all cases, the complexation takes place at the heteroatom attached to position 3 of the triazepine. Hence, although in general, thiocarbonyls are stronger bases than carbonyls in the gas phase, 5‐thioxo‐2,7‐dimethyl‐[1,2,4]‐triazepin‐3‐one behaves as an oxygen base towards I2. Experimental free energies in solution and gas‐phase computational values are linearly correlated. Copyright © 2009 John Wiley & Sons, Ltd.
Self‐doping PPV oligomers – electrochemistry and structure of the self‐doped systems
Authors: Baeke Jan K. , De Borger Roeland , Lemière Filip , Van Alsenoy Christian , Blockhuys Frank 
Published: March 2009

AbstractA novel class of self‐doping conjugated oligomers, E,E‐2‐(sulfoalkoxy)‐5‐alkoxy‐1,4‐bis[2‐(2,4,6‐trimethoxyphenyl) ethenyl]benzenes, is presented. The synthesis and spectroscopic characterisation of five such oligomers are described, and an electrochemical analysis using cyclic voltammetry is performed to determine the anodic peak potentials. A structural study is performed on six self‐doping oligomers in which the structures and energies of the possible mono‐molecular forms of the electrically conducting doped material are described and evaluated using Hirshfeld charges and the Quantum Theory of Atoms In Molecules. Copyright © 2009 John Wiley & Sons, Ltd.
Manifestations of string theory in astrophysical data and at the LHC
Authors: Nawata S. 
Published: March 2009

AbstractWith the advent of the LHC and the continuing influx of cosmological data, phenomenological aspects of string theory have received renewed attention in recent years and many problems have been properly incorporated in this framework. For instance, recent theoretical considerations in string theory have applied a statistical approach to the enormous landscape of metastable vacua. The large number of vacua may shed some light on the cosmological constant problem. In addition, in string theory, attempts have been made to address the hierarchy problem within the context of the existence of large or warped internal dimensions transverse to a braneworld where we are confined, which lowers the effective scale of gravity to the TeV region. If this were the case, unseen dimensions of the space‐time can be at the border of the energy domain within reach of the next generation of particle accelerators.Although the picture of the landscape may be the key to the cosmological constant problem, it is well‐known that the compactification of a string background to a four dimensional solution undergoing accelerating expansion is difficult, which is described by the no‐go theorem of Maldacena‐Nuñez. In the first part of this paper, we investigate the cosmological content of the Salam‐Sezgin supergravity which circumvents one of the hypotheses of the no‐go theorem of Maldacena‐Nuñez and consequently can support a de Sitter phase when lifted to string theory. We find a solution to the field equations in qualitative agreement with the observed dark energy density. The carrier of the acceleration in the present de Sitter epoch is a quintessence field slowly rolling down its exponential potential. Intrinsic to this model, there is a second modulus, which is automatically stabilized and acts as a source of cold dark matter with a mass proportional to an exponential function of the quintessence field.In the second part, we explore a “new physics” signal at LHC, in the processes pp →γ + jet and pp→γ γ. In D‐brane quivers, there are one or more additional U(1) gauge symmetries, beyond the U(1)Y of the standard model, which follows from the property that the gauge group for open strings terminating on a stack of N identical D‐branes is U(N) rather than SU(N) for N > 2. (For N = 2 the gauge group can be Sp(1) rather than U(2).) With this property, the photon will participate with the SU(N) gauge boson in string tree level scattering processes which in the standard model occur only at one‐loop level. In order to evaluate this stringy correction, we considered the processes gg → g γ and gg →γγ, and found that cross section measurements of the process pp →γ + jet at the LHC will attain 5 σ discovery reach on low scale string models for Mstring as large as 4 TeV.
Shared TP53 gene mutation in morphologically and phenotypically distinct concurrent primary small cell neuroendocrine carcinoma and adenocarcinoma of the prostate
Authors: Hansel Donna E. , Nakayama Masashi , Luo Jun , Abukhdeir Abde M. , Park Ben H. , Bieberich Charles J. , Hicks Jessica L. , Eisenberger Mario , Nelson William G. , Mostwin Jasek L. , De Marzo Angelo M. 
Published: March 2009

AbstractBACKGROUNDSmall cell carcinoma of the prostate is an uncommon neoplasm, the origin of which has been controversial. To address this, we performed transcriptome profiling and TP53 sequencing of concurrent small cell and prostatic adenocarcinoma to determine the relationship between these entities.METHODSWe identified an unusual case of primary prostate cancer that contained adjacent acinar adenocarcinoma (Gleason score 4 + 3 = 7) and small cell carcinoma. We performed laser capture microdissection to isolate tumor components and performed gene expression and TP53 gene sequence analysis on each component, with results validated by immunohistochemistry for PSA, PSAP, PSMA, androgen receptor, NKX 3.1 and neuroendocrine markers.RESULTSTranscriptome profiling of the carcinoma components identified 99 genes with a greater than 10‐fold differential expression between prostatic adenocarcinoma and small cell carcinoma, many of which have not been previously reported in prostate cancer. The small cell carcinoma component demonstrated upregulation of proliferative and neuroendocrine markers and tyrosine kinase receptors, and downregulation of cell adhesion molecules, supporting the aggressive nature of this form of carcinoma. Sequencing of the TP53 gene suggested a common clonal origin for both components.CONCLUSIONSThis is the first report of a primary small cell carcinoma of the prostate subjected to extensive molecular analysis and the first to show a clonal relation between two morphologically distinct prostate cancer types. The evidence of progression to small cell carcinoma may yield important insights into the pathogenesis of this entity and provide a novel spectrum of molecular markers to further dissect cellular pathways important in tumor progression. Prostate 69:603–609, 2009. © 2009 Wiley‐Liss, Inc.
Overexpression of 5α‐reductase type 1 increases sensitivity of prostate cancer cells to low concentrations of testosterone
Authors: Thomas Lynn N. , Douglas Robert C. , Rittmaster Roger S. , Too Catherine K.L. 
Published: March 2009

AbstractINTRODUCTIONConversion of testosterone to dihydrotestosterone (DHT) by the enzymes 5α‐reductase types 1 (5αR1) and 2 (5αR2) is important for normal and pathological growth of the prostate. The predominant isoenzyme in normal prostate is 5αR2. However, prostate cancer (PCa) development is accompanied by a decrease in 5αR2 and an increase in 5αR1. The biological significance of increased 5αR1 expression is not fully understood. Therefore, the aim of this study was to determine the effect of overexpression of 5αR1 on growth and prostate‐specific antigen (PSA) production in PCa cells.MATERIALS AND METHODSLNGK‐9 PCa cells, transiently transfected with pTRE‐5αR1 or pTRE alone, were cultured in the presence or absence of testosterone at varying concentrations. Cell growth and PSA secretion were measured after 4–6 days. Cyclin E1, Ki67, and PSA mRNA levels were evaluated using RT‐PCR after 24 hr of treatment.RESULTS10 pM testosterone increased growth of pTRE‐5αR1 transfectants by 54.1% over cells grown in the absence of testosterone, compared to 25.0% in pTRE transfectants (P < 0.01). Likewise, PSA secretion was increased by 56‐fold in pTRE‐5αR1 transfectants treated with 10 pM testosterone, compared to 26‐fold in pTRE transfectants (P < 0.01). At concentrations of testosterone above 10 pM, the stimulatory effect on growth and PSA secretion was not distinguishable between pTRE‐5αR1 and pTRE transfectants.CONCLUSIONSThese results demonstrate that upregulation of 5αR1 enhances the cellular response to low, but not high, concentrations of testosterone. This explains one mechanism by which castration‐recurrent PCa can proliferate in the presence of castrate levels of circulating testosterone. Prostate 69:595–602, 2009. © 2009 Wiley‐Liss, Inc.
Effect of phase separation on optical and electrical properties of Sn–Sb–Se glassy films
Authors: Kumar Praveen , Thangaraj R. , Sathiaraj T. S. 
Published: March 2009

AbstractThis paper reports the effect of phase separation on the structural, optical and electrical properties of thermally evaporated Snx Sb20Se70–x (x = 10, 11, 12.5) films. The X‐ray diffraction studies of the devitrified films show the crystallization of SnSe2, Sn2Sb4Se8 and Sn4Sb4Se10 phases for x = 12.5 film, while Sb2Se3 is the other major phase in all the film samples. The optical constants are calculated by using Swanpole's standard envelop method. The dispersion of the refractive index is discussed in terms of the Cauchy's dispersion relation and the Wample–DiDomenico (WDD) single‐oscillator model in the weak absorption region. The optical gap and the tailing parameter were calculated in the fundamental absorption region, while the Urbach energy was calculated by using the value of extinction coefficients. The dc conductivity measurements with temperature have also been performed and electrical conduction has been discussed in conjunction with the Meyer–Neldel rule for the present system. These results have been discussed taking into consideration the structural modifications induced by the phase separation in the present system. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Isochronal shear stress relaxation and recovery of bulk and ribbon glassy Pd40Cu30Ni10P20
Authors: Nguyen N. T. N. , Khonik S. V. , Khonik V. A. 
Published: March 2009

AbstractMeasurements of torque relaxation upon isochronal (= linear) heating of bulk and ribbon glassy Pd40Cu30Ni10P20 differing ∼104‐fold in the production quenching rates have been performed. It has been found that torque relaxation in bulk samples is notably faster than that in the ribbons despite the fact that the former are denser. Preannealing at a temperature Ta strongly decreases the relaxation rate at all temperatures T ≤ Ta and shifts the relaxation curves towards higher temperatures similarly in bulk and ribbon samples. The relaxation law has been determined. It has been revealed that rapid quenching of thermally aged samples from the supercooled liquid state recovers the ability to plastic flow. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferroelectrics at the nanoscale
Authors: Gregg J. M. 
Published: March 2009

AbstractThere are several factors which make the investigation and understanding of nanoscale ferroelectrics particularly timely and important. Firstly, there is a market pressure, primarily from the electronics industry, to integrate ferroelectrics into devices with progressive decreases in size and increases in morphological complexity. This is perhaps best illustrated through the roadmaps for product development in FeRAM (Ferroelectric Random Access Memory) where the need for increases in bit density will require a move from 2D planar capacitor structures to 3D trenched capacitors in the next few years. Secondly, there is opportunity for novel exploration, as it is only relatively recently that developments in thin film growth of complex oxides, self‐assembly techniques and high‐resolution ‘top–down’ patterning have converged to allow the fabrication of isolated and well‐defined ferroelectric nanoshapes, the properties of which are not known. Thirdly, there is an expectation that the behaviour of small scale ferroelectrics will be different from bulk, as this group of functional materials is highly sensitive to boundary/surface conditions, which are expected to dominate the overall response when sizes are reduced into the nanoscale regime.This feature article attempts to introduce some of the current areas of discovery and debate surrounding studies on ferroelectrics at the nanoscale. The focus is directed primarily at the search for novel size‐related properties and behaviour which are not necessarily observed in bulk. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron emission from amorphous carbon film on discontinuous Ag islands
Authors: Zhu Dan , Li Dejie , Wang Jian 
Published: March 2009

AbstractElectron emission from amorphous carbon thin film on discontinuous Ag nanoislands is reported. The discontinuous Ag islands are formed by evaporating Ag film at a substrate temperature of 350 °C, introduce thickness ununiformity of carbon thin film on it and help forming a lap of μm width as the electron emission area. The electron emission has a threshold and performances as an exponential type emission to the anode voltage. Uniform and stable electron emission can be reproducibly obtained. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN HEMT and MMIC development at Fraunhofer IAF: performance and reliability
Authors: Waltereit P. , Bronner W. , Quay R. , Dammann M. , Kiefer R. , Müller S. , Musser M. , Kühn J. , Raay F. van , Seelmann M. , Mikulla M. , Ambacher O. , Rijs F. van , Rödle T. , Riepe K. 
Published: March 2009

AbstractWe present a systematic study of epitaxial growth, processing technology, device performance and reliability of our GaN HEMTs and MMICs manufactured on 3 inch SiC substrates. Epitaxy and processing are optimized for both performance and reliability. The deposition of the AlGaN/GaN HEMT epitaxial structures is designed for low background carrier concentration and a low trap density in order to simultaneously achieve a high buffer isolation and low DC to RF dispersion. Device fabrication is performed using standard processing techniques involving both electron‐beam and stepper lithography. Gate lengths of 250 nm and 500 nm are employed for 10 GHz and 2 GHz applications, respectively. The developed HEMTs demonstrate excellent high‐voltage stability, high power performance and large power added efficiencies. Devices exhibit two‐terminal gate–drain breakdown voltages in excess of 160 V (current criterion 1 mA/mm) across the entire 3 inch wafer with parasitic gate and drain currents well below 1 mA/mm when biased up to 80 V drain bias under pinch‐off conditions. Load‐Pull measurements at 2 GHz on 800 μm gate width devices return a well‐behaved relationship between bias‐voltage and output‐power as well as power‐added‐efficiencies beyond 60% up toUDS= 100 V. For a drain bias of 100 V an output‐power‐density around 22 W/mm with 26 dB linear gain is obtained. On large devices (32 mm gate width packaged in industry‐standard ceramic packages) an output power beyond 100 W is achieved with a PAE above 50% and a linear gain around 15 dB. Dual‐stage MMICs in microstrip transmission line technology yield a power added efficiency of 40% at 8.56 GHz for a power level of 11 W. A single‐stage MMIC yields a PAE of 46% with 7 W of output power atVDS= 28 V. Reliability is tested on HEMT devices having a gate periphery of 8 × 60 μm at an operating bias of 50 V under both DC and RF conditions. About 10% drain‐current change under DC‐stress (50 mA/mm) is observed after more than 1000 h of operation with an extrapolated drain‐current degradation below 20% after 200000 h (more than 20 years) of operation. Under RF stress (2 GHz, 1 dB compression) the observed change in output power density is below 0.2 dB after more than 1000 h. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of aluminum carbide buffer layer on growth and self‐separation of m ‐plane GaN by hydride vapor phase epitaxy
Authors: Sasaki Hitoshi , Sunakawa Haruo , Sumi Norihiko , Yamamoto Kazutomi , Usui Akira 
Published: March 2009

AbstractAn m ‐plane GaN layer with a thickness of approximately 500 μm was successfully obtained on a conventional m ‐plane sapphire substrate with a diameter of 2 inches. The GaN layer was grown by hydride vapor phase epitaxy (HVPE) on a buffer layer of low‐temperature (LT) GaN/Al4C3 structure deposited on the sapphire substrate by metalorganic chemical vapor deposition (MOCVD). The deposition temperature of the Al4C3 layer affected the appearance of the m ‐plane GaN layer. The c‐axes of the GaN layer is parallel to the a‐axis of the sapphire substrate. The thick GaN layer spontaneously separated from the sapphire substrate after its growth. Complete self‐separation of the m ‐plane GaN from the sapphire substrate was achieved with good reproducibility when the thickness of the Al4C3 layer was 70–100 nm. By lapping and polishing the self‐separated GaN crystal, a freestanding m ‐plane GaN wafer with a diameter of 45 mm was obtained. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of m ‐GaN layers by epitaxial lateral overgrowth from sapphire sidewalls
Authors: Okada Narihito , Kawashima Yuji , Tadatomo Kazuyuki 
Published: March 2009

AbstractNonpolar m ‐plane GaN layers were fabricated by epitaxial lateral overgrowth from etched sapphire sidewalls. The m ‐plane GaN layers with c ‐direction growth were grown from patterned c ‐plane and a ‐plane sapphire substrates with a ‐plane or c ‐plane sidewalls using a low‐temperature buffer layer. The growth of GaN from the surface was prevented by a SiO2 mask, and that from the bottom of grooves was also prevented by deep grooves. Thus, the growth orientation relative to the surface of the GaN layer was determined by the growth of the GaN layer from the sapphire sidewalls. Consequently, m ‐plane GaN layers were grown on c ‐plane sapphire with a ‐plane sidewalls or on a ‐plane sapphire with c ‐plane sidewalls with the terrace regions covered with a SiO2 mask and deep grooves. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
222–282 nm AlGaN and InAlGaN‐based deep‐UV LEDs fabricated on high‐quality AlN on sapphire
Authors: Hirayama Hideki , Fujikawa Sachie , Noguchi Norimichi , Norimatsu Jun , Takano Takayoshi , Tsubaki Kenji , Kamata Norihiko 
Published: March 2009

AbstractWe demonstrate 222–282 nm AlGaN and InAlGaN‐based deep ultraviolet (DUV) light‐emitting diodes (LEDs) fabricated on low threading dislocation density (TDD) AlN template. Low TDD AlN templates were realized by using ammonia (NH3) pulse‐flow multilayer (ML) growth technique. The edge‐ and screw‐type dislocation densities of AlN layer were reduced to 7.5 × 108 and 3.8 × 107, respectively. Single‐peaked electroluminescence (EL) were obtained for 222– 273 nm AlGaN multi quantum well (MQW) DUV‐LEDs. We obtained the maximum output power of 1.1 mW and 4.0 mW for the AlGaN‐QW LEDs with wavelengths of 241 nm, 256 nm, respectively, under room temperature (RT) CW operations. The maximum output power of 227 nm and 222 nm AlGaN‐QW were 0.15 mW and 0.014 mW, respectively, under RT pulsed operation. The maximum external quantum efficiency (EQE) of the 227 nm and 250 nm AlGaN LEDs were 0.2% and 0.43%, respectively. We also fabricated 280 nm band quaternary InAlGaN‐MQW DUV‐LEDs with n‐type and p‐type InAlGaN layers on ML‐AlN templates. We demonstrated extremely high internal quantum efficiency (IQE) of 284 nm InAlGaN‐QW emission, which was confirmed by the fact that the ratio of the integrated intensity of the RT‐PL against the 77 K‐PL was 86%. The maximum output power and EQE of the 282 nm InAlGaN LED were 10.6 mW and 1.2%, respectively, under RT CW operation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)