bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Stress in Doped Silicate Glasses (B,P) Deposited by PECVD and LPCVD
Authors: Bouchard H. , Azelmad A. , Currie J.F. , Meunier M. , Blain S. , Darwall T. 
Published: March 2011

ABSTRACTUsing an in situ stress measurement technique which measures stress as a function of annealing temperature, we have investigated the effect of phosphorous and boron doping of silicon dioxide glass films deposited by low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD). The stress at room temperature is σi. Upon heating, it increases to a maximum, σm, corresponding to a temperature Tm, above which the stress is reduced to zero at a temperature T0. All these parameters plus the expansion coefficient are dependent on dopant concentrations and deposition technique.
Sintering Behavior of Ba2CaWO6-Doped-Tungsten
Authors: Ruud J.A. , Bewlay B.P. 
Published: March 2011

AbstractThe sintering behavior of Ba2CaWO6 co-sintered with W powder was investigated. Measurements of density and mass loss of sintered compacts showed that the Ba2CaWO6-doped-W had a lower density than undoped W and that there was little volatilization of Ba2CaWO6 at temperatures below 1750 °C. The activation energies for densification of Ba2CaWO6-doped-W and undoped W were both measured to be 389 kJ/mol, which indicates the same densification mechanism, grain boundary diffusion, operated for both materials. The reduced densification kinetics of the Ba2CaWO6-doped-W was probably due to increased coarsening in the early stages of sintering.
Rapid Thermal Annealing of As in Si
Authors: Hoyt J. L. , Gibbons J. F. 
Published: March 2011

ABSTRACTThe results of a detailed investigation of the diffusion of ion implanted As in Si during Rapid Thermal Annealing (RTA) are reported. A series of experiments has been performed on samples implanted with As in a wide range of concentrations. The use of an improved thermocouple bonding technique enables precise measurement and control of the temperature versus time cycle for each individual sample. The RTA apparatus is designed to perform high vacuum annealing, eliminating the complications associated with point defect generating mechanisms at the surface, which are known to influence the diffusion of impurities in Si. Sample analysis includes depth profiling by SIMS and RBS, and electrical characterization employing VanderPauw and Spreading Resistance measurements.The resulting profiles have been analyzed via a numerical solution of the diffusion equation subject to the appropriate boundary conditions. With an effective As diffusivity of the form we find good simulation of all measured profiles with the standard values of D0 and D- from SUPREMIII and a one parameter fit to D= Recent results on the redistribution of low dose As implants in heavily phosphorus doped Si illustrate the strong Fermi level dependence. The model has also been successfully used to simulate RTA data in the literature where careful temperature measurements have been made.
Extended Defects in Amorphized and Rapid-Thermally Annealed Silicon
Authors: Maher D. M. , Knoell R. V. , Ellington M. B. , Jacobson D. C. 
Published: March 2011

ABSTRACTThe characterization of microstructures is fundamentally important to investigations of amorphization which is induced by ion implantation and recrystallization which occurs by solid-phase, epitaxial regrowth. In this paper, microstructures of amorphized, partially regrown and fully regrown layers are described in terms of extended-defect states of the material. Initial states (i.e. amorphized) and final states (i.e. solid-phase regrown and then reordered) are defined. Transmission electron microscopy and Rutherford backscattering/ion-channeling are the analytical techniques which are used in the characterization.
HIGH CONTROLLABILITY OF CARRIER CONCENTRATION OF p--LPE InP BY Mn DOPING
Authors: TANAHASHI T. , KONDO M. , TAKANOHASHI T. , KOTAKI Y. , ISOZUMI S. , NAKAJIMA K. 
Published: March 2011

AbstractExtremely high controllability of the carrier concentration of p--InP below 1×l0l6 cm−3 has been obtained by using Mn as a dopant. Applying Mndoped p--InP to the current confining layers of 1.3 µm buried heterostructure (BH) laser diodes has enabled threshold currents as low as 12 mA.
Formation Kinetics of Thermal Donors in Silicon
Authors: Borenstein Jeffrey T. , Peak David , Corbett James W. 
Published: March 2011

ABSTRACTThe kinetics of thermal donor formation in Czochralski-silicon at ca. 450° C are explained by a simple model based on the work of Suezawa and Sumino which derives forward and reverse reaction rates for each electrically active species from the general features of the infrared electronic absorption spectra. The model, which is independent of the chemical nature of the thermal donor core, assumes that all thermal donors beyond the first donor species are chemically stable at the donor formation temperature, and approximates the reactions for species smaller than the first thermal donor as being in chemical equilibrium. The model is shown to be consistent with both sets of the available IR spectra of thermal donors (Oeder-Wagner and Suezawa-Sumino) when differences in the annealing temperature and initial oxygen concentration are taken into account.
Characterization of Long Period Polytypoid Structures in The Al2O3-AlN System
Authors: Krishnan Kannan M. , Rai R.S. , Thomas G. , Corbin N.D. , McCauley J.W. 
Published: March 2011

AbstractLong period polytypoid structures observed along the pseudobinary Al2O3-AlN composition join at a composition of 95 mol% A1N have been investigated by convergent beam electron diffraction and lattice imaging. Two new long period structures, 32H (Ramsdell notation) and 16H with c-periodicities of 8.3 nm and 4.07 nm respectively, have been independently identified by these two techniques. However, the 32H polytypoid was sometimes found to be intergrown with faulted 27R long period structure of periodicity 7.2 nm. Further, it has been shown that the 32H polytypoid is stabilized by local compositional fluctuations during the sintering process.
Grain Boundary Structures in High-Purity Al2O3 Bicrystals Grown From the Melt
Authors: Morris P.A. , Coble R.L. 
Published: March 2011

AbstractThe clean room processing, firing and crystal growth techniques required to produce high-purity Al2O3 crystals and bicrystals with [2110] tilt boundaries near low Σ misorientations are described. The chemical analysis requirements for high-purity ceramic materials are discussed. The boundary characteristics of the θ=33.2°, near Σ = 11, misorientation and the applicability of the CSL model to describe the observed facet planes is determined. The periodicity of the dislocations present in the boundary is 21 nm. STEM analysis of the grain boundary region indicates no second phase or detectable impurity concentrations. The importance of gra in boundary structure investigations in high-purity materials and of chemically well-characterized boundaries is discussed.
Dynamic Compressive Strength of Cementitious Materials
Authors: Malvern L. E. , Tang T. , Jenkins D. A. , Gong J. C. 
Published: March 2011

ABSTRACTFinite-element codes for structural response of reinforced concrete use as a parameter the unconfined compressive strength of the concrete, fc', which is sometimes increased by an arbitrary factor for dynamic loading. The objective of this research is to determine the rate dependence of fc' and eventually to model the rate-dependent constitutive behavior. Results of tests with a small Kolsky bar system and of a newly built larger system on concrete with a maximum aggregate size 1/2 inch are reported with strain rates at the maximum stress from 50 to 800/sec for mortar and from 5 to 120/sec for concrete. An apparent rate dependence up to almost twice the static strength is observed for both. The mortar shows an apparent linear dependence, while the high-strength concrete shows an approximately logarithmic dependence on the strain rate at the maximum stress, over the dynamic range observed. Some questions about specimen size effects and about how much of the apparent strain-rate effect is really a lateral inertia confinement effect are as yet unresolved. Continuing research is focused on observation of the lateral motion to assess lateral inertia effects in unconfined specimens and on passive confinement by steel jackets. Future efforts will be directed toward constitutive modeling.
Crack Growth in Hardened Cement Paste
Authors: Baldie K. D. , Pratt P. L. 
Published: March 2011

ABSTRACTThe subcritical crack growth parameter (n) has been determined both from the variation in the crack velocity (V) with stress intensity (K) in double torsion specimens, and from the variation in critical stress intensity (Klc) with loading rate (x) in single edge-notch bend specimens. As in previous cases for hardened cement paste (HCP), and other inhomogeneous materials, the value of n determined using double torsion specimens (˜70) was higher than that determined using SENB (˜30).Backscattered electron image examination of cracks in polished sections of HCP has shown that all of the components, both hydration products and anhydrous phases, are involved in determining crack paths although, as expected; calcium silicate hydrate and calcium hydroxide form the majority of the crack path; unnhydrated cement cores are resistant to crack growth and cause the crack to deviate around them. There is some evidence that crack growth occurs by the formation and coalescence of microcracks ahead of the crack tip, with only a limited formation of an actual process zone.
Carbonation in Concrete Made of Blended Cements
Authors: Maage Magne 
Published: March 2011

ABSTRACTConcrete with different strengths was produced using four types of cements, one ordinary Portland cement (OPC) and three blended cements with 10% pulverized fuel ash (pfa), 25% pfa, and 15% slag respectively. The pfa was added to the cement clinker during the end of the grinding process. The the slag was preground. Carbonation was tested using the phenolphtalein method. The concretes were exposed to four different climates: (1) 50% RH, 20 C and normal CO2 content (0.03%) of air; (2) 50% RH, 20 C and 0.1% CO2; (3) outside in the natural environment unsheltered from rain; (4) outside in the natural environment sheltered from rain. Curing time before exposure was varied. The preliminary results showed that concrete with blended cements carbonated somewhat faster than concrete with OPC. The influence of curing time before exposure and exposure condition was found to be evident but independent of the blend.
Molecular beam epitaxy of GaSb/AlSb optical device layers on Si(100)
Authors: Malik R. J. , van der Ziel J. P. , Levine B. F. , Bethea C. G. , Petroff P. M. , Walker J. , Hamm R. 
Published: March 2011

ABSTRACTWe report for the first time the growth of GaSb/AlSb multilayers and alloys on Si(100) by molecular beam epitaxy. High quality films were achieved in spite of the large lattice constant mismatch of 12%. Room temperature, optically pumped pulsed lasers emitting at 1.8μm have been demonstrated. Lateral photoconductive detectors with responsivities of 0.18 A/W have also been made. The film nucleation on the Si substrate was observed in-situ by reflection high energy electron diffraction. Characterization of the grown epilayers and preliminary optical device results are described.
Rapid Thermal Annealing of Amorphous Hydrogenated Carbon (a-C:H) Films
Authors: Alterovitz Samuel A. , Pouch John J. , Warner Joseph D. 
Published: March 2011

ABSTRACTAmorphous hydrogenated carbon (a-C:H) films were deposited on silicon and quartz substrates by a 30 kHz plasma discharge technique using methane. Rapid thermal processing of the films was accomplished in nitrogen gas using tungsten halogen light. The rapid thermal processing was done at several fixed temperatures (up to 600°C), as a function of time (up to 1800 sec). The films were characterized by optical absorption and by ellipsometry in the near UV and the visible. The bandgap, estimated from extrapolation of the linear part of a Tauc plot, decreases both with the annealing temperature and the annealing time, with the temperature dependence being the dominating factor. The density of states parameter increases up to 25 percent and the refractive index changes up to 20 percent with temperature increase. Possible explanations of the mechanisms involved in these processes are discussed.
Nuclear Reaction Analysis of Shallow B And Bf2 Implants in Si
Authors: Ridgway Mark C. , Scanlon P J. , Whitton J.L. 
Published: March 2011

ABSTRACTImpurity diffusion induced by rapid thermal annealing (RTA) has been investigated for low energy B and BF2 implants in crystalline and preamorphized Si. A 50 keV 2×1015/cm2 Si self-implant was used for preamorphization. Samples were annealed with an oxide cap in an AG Associates HEATPULSE system (model 210T). Prior to the impurity depth profiling measurements, the SiO2 was removed with dilute HF. Significant B diffusion to theSiO2/Si interface was observed for a 1050°C/10 s anneal of 10 keV 3×1015/cm2 implanted;11B in crystalline and preamorphized Si. B interfacial concentrations were comparableto peak concentrations in unannealed samples. Diffusion of B and F to the SiO2/Si interface, and impurity gettering by ion straggling damage were observed for a 1050°C/10 s anneal of 45 keY 3×1O15/cm2 implanted 49BF2 in crystalline Si.though a loss F was apparent.Depth profiles were determined with nuclear reaction analysis (NRA) [1-3], specifically the 11B(ρ,α0)8 Be(ER=163 key) [4] and 19F(ραγ)160 (ER - 340 keV) [5] reactions for 1lB and 19F profiling, respectively. This technique is sensitive to impurities at or near the surface and can reveal impurity diffusion to near-surface regions not usually detectable with secondary ion mass spectrometry (SIMS). NRA depth profiling has shownthat RTA can result in significant impurity diffusion to the SiO2/Si interface for B implanted in crystalline and preamorphized Si, and BF2 implanted in crystalline Si. Impurity concentrations at the interface are estimated to be in excess of 1020/cm3 for the implantation and annealing conditions used in this report. BF2 implanted in preamorphized Si showed greatly reduced impurity concentrations at the interface. A knowledge of the impurity concentrations at the substratesurface or the SiO2/Si interface becomes increasingly important as device dimensions decrease. Matrix effects make such measurements difficult with SIMS.
Optical, Chemical and Electrical Characterization of Ion-Etched Gallium Arsenide Surfaces
Authors: Feng G. F. , Holtz M. , Zallen R. , Epp J. M. , Dillard J. G. , Cole E. , Johnson P. , Sen S. , Burton L. C. 
Published: March 2011

ABSTRACTUltraviolet reflectivity, surface chemistry and electrical measurements are reported for Ar+-ion bombarded (100) GaAs surfaces, with ion energies from 0.5 to 4 keV. Changes in reflectivity spectra, surface stoichiometry and Schottky diode parameters are reported as functions of ion energy.
Alcohol Consumption in Early Adulthood and Schooling Completed and Labor Market Outcomes at Midlife by Race and Gender
Authors: Sloan Frank A. , Grossman Daniel S. 
Published: March 2011

Objectives. We assessed the relation of alcohol consumption in young adulthood to problem alcohol consumption 10 years later and to educational attainment and labor market outcomes at midlife. We considered whether these relations differ between Blacks and Whites. Methods. We classified individuals on the basis of their drinking frequency patterns with data from the 1982 to 1984 National Longitudinal Survey of Youth 1979 (respondents aged 19–27 years). We assessed alcohol consumption from the 1991 reinterview (respondents aged 26–34 years) and midlife outcomes from the 2006 reinterview (respondents aged 41–49 years). Results. Black men who consumed 12 or more drinks per week at baseline had lower earnings at midlife, but no corresponding relation for Black women or Whites was found. Black men and Black women who consumed 12 or more drinks per week at baseline had lower occupational attainment than did White male non-drinkers and White female non-drinkers, respectively, but this result was not statistically significant. Conclusions. The relation between alcohol consumption in young adulthood and important outcomes at midlife differed between Blacks and Whites and between Black men and Black women, although Blacks’ alcohol consumption at baseline was lower on average than was that of Whites.
Impact of Poor Oral Health on Children's School Attendance and Performance
Authors: Jackson Stephanie L. , Vann William F. , Kotch Jonathan B. , Pahel Bhavna T. , Lee Jessica Y. 
Published: March 2011

Objectives. We examined school days missed for routine dental care versus dental pain or infection to determine the relationship between children's oral health status and school attendance and performance. Methods. We used 2008 data from the North Carolina Child Health Assessment and Monitoring Program. The study sample, weighted to reflect the state's population, included 2183 schoolchildren. Variables assessed included school absences and performance, oral health status, parental education, health insurance coverage, race, and gender. Results. Children with poor oral health status were nearly 3 times more likely (odds ratio = 3.89; 95% confidence interval = 1.96, 7.75) than were their counterparts to miss school as a result of dental pain. Absences caused by pain were associated with poorer school performance (P < .05), but absences for routine care were not. Mediation analyses revealed that oral health status was associated with performance independent of absence for pain. Conclusions. Children with poorer oral health status were more likely to experience dental pain, miss school, and perform poorly in school. These findings suggest that improving children's oral health status may be a vehicle to enhancing their educational experience.
Effects of denaturing acid on the self-association behaviour of poly(ethylene glycol)-block-poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) copolymer in ethanol
Authors: Zhu Guo-Quan , Gao Qiao-Chun , Wang Fa-Gang , Li Guo-Chang , Wang Ping 
Published: March 2011

AbstractPoly(ethylene glycol)-block-poly(γ-benzyl l-glutamate)-graft-poly(ethylene glycol) (PEG-b-PBLG-g-PEG) copolymer was synthesised by the ester exchange reaction of PEG-block-PBLG copolymer with mPEG. The self-association behaviour of PEG-b-PBLG-g-PEG in mixtures of ethanol, chloroform, and trifluoroacetic acid as denaturing acid was investigated by transmission electron microscopy, nuclear magnetic resonance spectroscopy, FT-IR spectroscopy, dynamic light scattering, and viscometry. It was revealed that the increase in denaturing acid content in the mixed system not only promoted the critical micelle concentration but also changed the morphology of the polymeric micelles from elliptical to spherical.
Detonation Deposited Fe-Al Coatings Part II: Transmission Electron Microscopy of Interlayers and Fe-Al Intermetallic Coating Detonation Sprayed onto the 045 Steel Substrate
Authors: Pawłowski A. , Senderowski C. , Wołczyński W. , Morgiel J. , Major Ł. 
Published: March 2011

Detonation Deposited Fe-Al Coatings Part II: Transmission Electron Microscopy of Interlayers and Fe-Al Intermetallic Coating Detonation Sprayed onto the 045 Steel Substrate
The microstructure of detonation gaseous sprayed (DGS) transition layers of Ni(Al), Ni(Cr) and subsequent coating of Fe-Al intermetallic phases deposited on the 045 steel were studied in the paper using transmission electron microscopy. In order to identify phases in the particular interlayers the selected area electron diffraction (SAED) and an energy dispersive X-ray microanalysis (EDX) were applied. It was found that the Ni(Al) interlayer contained basically pure nickel with a small fraction of NiAl phase. The Al based amorphous phase was also observed its area in the form of bands. The Ni(Cr) interlayer basically contained Ni-rich small grains. Pure chromium in the Ni matrix appeared in the vicinity of Fe-Al coating in the shape of bow-like bands, parallel to the coating. The boundary between the Ni(Cr) layer and the Fe-Al coating revealed abrupt decrease of the Ni content in the coating at simultaneous rapid increase of the Fe amount. Improper Al/Cr ratio within the Ni matrix seems to be responsible for the formation of Al-oxides and the bands of almost pure Cr and Ni(Cr) layers and resulting decrease of interlayer adherence.
Effects of selected groundwater chemical traits on a salt marsh community
Authors: Kilinç Mahmut , Kutbay Hamdi , Yalçin Erkan , Bilgin Ali , Avci Kenan , Topaloglu Solmaz 
Published: March 2011

Effects of selected groundwater chemical traits on a salt marsh communityElectrical conductivity, exchangeable sodium ratio and water depth have negative impacts, whereas soil organic matter concentration has a positive impact on Black Sea salt marsh vegetation. The most saline soils were characterized bySalicornia prostratavegetation and associated with exchangeable sodium ratio.Alhagi pseudalhagiandTamarix smrynensispopulations were associated with water depth, whileJuncus littoralis, Ammophila arenariaandE. paraliaswere associated with soil organic matter.Euphorbia paralias, Ammophila arenariaandIris orientaliswere associated with acidity.
Early post-fire changes in Pinus brutia forests (Amanos Mountains, Turkey)
Authors: Türkmen Necattin , Düzenli Atabay 
Published: March 2011

Early post-fire changes inPinus brutiaforests (Amanos Mountains, Turkey)We studied the species composition and soil nutrients in aPinus brutiaforest after a fire that occurred in 1989. Four permanent plots were created in the burnt and not burnt areas in the Amanos Mountains of Turkey. The floristic richness, biological spectra, above ground phytomass and soil features in the study areas were assessed during the first three years after the fire. After the fire, we found a reduced amount of organic matter (14.3%), total nitrogen (22%) and soil water saturation (13.1%), but an increased amount of available phosphorus (71%), acidity (3.6%), cation exchange capacity (9.9%), exchangeable sodium (20.8%) and exchangeable potassium (37.1%). The aboveground phytomass in the burned area reached 5284 kg ha-1, the third year after the fire. Forty-six pre-fire species were renewed in the first three years after the fire.Juniperus oxycedruscould not renew within three years after the fire. Pine phytomass has increased five times within three years after the fire.
Stratified Subcartesian Spaces
Authors: Lusala Tsasa , Śniatycki Jędrzej 
Published: March 2011

AbstractWe show that if the family of orbits of all vector fields on a subcartesian space P is locally finite and each orbit in is locally closed, then defines a smooth Whitney A stratification of P. We also show that the stratification by orbit type of the space of orbits M/G of a proper action of a Lie group G on a smooth manifold M is given by orbits of the family of all vector fields on M/G.
Role of Hysteroscopy Prior to Assisted Reproductive Techniques in Patients with Previous IVF Failure
Authors: Dalal Rutvij Jay , Palshetkar Nandita P 
Published: March 2011

ABSTRACTBackgroundThere have been numerous advances in the area of assisted reproduction. Among the various reasons of implantation failure, intrauterine lesions play an important role.ObjectiveThe aim of the present study is to evaluate the role of hysteroscopy prior to any assisted reproductive technique in patients who had previous one or more failed IVF cycle(s).Materials and methodsIt is a retrospective study of 248 women who attended our infertility clinic over a period of 18 months, who had a variable number of failed IVF cycles previously.ResultsOut of the 248 women studied, in 62 (25%) patients, intrauterine pathology was detected, which when rectified by hysteroscopy gave a considerable increase in pregnancy rate.ConclusionAccording to this study it can be concluded that evaluating the uterine cavity is an important step before any assisted reproductive procedure.