bluuebunny/crossref_metadata_2025 huggingface dataset:
DLBS1033, A Protein Extract from Lumbricus rubellus, Possesses Antithrombotic and Thrombolytic Activities
Authors: Trisina Jessica , Sunardi Febrina , Suhartono Maggy T. , Tjandrawinata Raymond R.
Published: March 2011

The medicinal value of earthworm has been widely known since the history of Asian ancient medicine. This present study aims to determine the mechanism of action and effect of a standardized extract of Lumbricus rubellus named as DLBS1033. The fibrinogen degradation, antiplatelet aggregation, and ex vivo antithrombotic assay using human blood were performed to study antithrombotic activity. Fibrin plate and clot lysis assay were also done to examine thrombolytic properties. DLBS1033 was found to possess fibrinogenolytic activity on α‐, β‐, and γ‐chain of fibrinogen. It also induced antiplatelet aggregation and prolonged blood clotting time, which further confirmed its antithrombotic properties. In addition, thrombolytic properties of DLBS1033 were shown with its fast and long‐acting fibrinolytic activity, as well as its effective blood clot lysis activities. In conclusion, DLBS1033 conferred antithrombotic and thrombolytic action which could be used as a safe and promising oral thrombolytic drug.
Executive Functions in Chronic Mesial Temporal Lobe Epilepsy
Authors: Zamarian Laura , Trinka Eugen , Bonatti Elisabeth , Kuchukhidze Giorgi , Bodner Thomas , Benke Thomas , Koppelstaetter Florian , Delazer Margarete
Published: March 2011

There is no consensus as to whether mesial temporal lobe epilepsy (MTLE) leads to executive function deficits. In this study, we adopted an extensive neuropsychological test battery and assessed different executive functions in chronic, unilateral MTLE. Performance of MTLE patients was compared with that of healthy peers and with normative data. Several MTLE patients had scores below cut-off or below the 10th percentile of normative data. Scores of the whole patient group were overall in the average range of normative data. Relative to controls, MTLE patients performed poorly in tests of working memory, cognitive flexibility, categorical verbal fluency, set-shifting, categorization, and planning. These findings raise an important methodological issue as they suggest that executive function deficits in chronic MTLE may be individually variable and that their assessment should include different tests. Deficits in chronic MTLE are not limited to temporal lobe functions, such as memory, but may extend to extra temporal cognitive domains, such as executive functions.
Joint Inflammation and Early Degeneration Induced by High‐Force Reaching Are Attenuated by Ibuprofen in an Animal Model of Work‐Related Musculoskeletal Disorder
Authors: Driban Jeffrey B. , Barr Ann E. , Amin Mamta , Sitler Michael R. , Barbe Mary F.
Published: March 2011

We used our voluntary rat model of reaching and grasping to study the effect of performing a high‐repetition and high‐force (HRHF) task for 12 weeks on wrist joints. We also studied the effectiveness of ibuprofen, administered in the last 8 weeks, in attenuating HRHF‐induced changes in these joints. With HRHF task performance, ED1+ and COX2+ cells were present in subchondral radius, carpal bones and synovium; IL‐1alpha and TNF‐alpha increased in distal radius/ulna/carpal bones; chondrocytes stained with Terminal deoxynucleotidyl Transferase‐ (TDT‐) mediated dUTP‐biotin nick end‐labeling (TUNEL) increased in wrist articular cartilages; superficial structural changes (e.g., pannus) and reduced proteoglycan staining were observed in wrist articular cartilages. These changes were not present in normal controls or ibuprofen treated rats, although IL‐1alpha was increased in reach limbs of trained controls. HRHF‐induced increases in serum C1,2C (a biomarker of collagen I and II degradation), and the ratio of collagen degradation to synthesis (C1,2C/CPII; the latter a biomarker of collage type II synthesis) were also attenuated by ibuprofen. Thus, ibuprofen treatment was effective in attenuating HRHF‐induced inflammation and early articular cartilage degeneration.
Antitumor and HIV‐1 Reverse Transcriptase Inhibitory Activities of a Hemagglutinin and a Protease Inhibitor from Mini‐Black Soybean
Authors: Ye Xiu Juan , Ng Tzi Bun
Published: March 2011

Protease inhibitors (PIs) and hemagglutinins are defense proteins produced by many organisms. From Chinese mini‐black soybeans, a 17.5‐kDa PI was isolated using chromatography on Q‐Sepharose, SP‐Sepharose, and DEAE‐cellulose. A 25‐kDa hemagglutinin was purified similarly, but using Superdex 75 instead of DEAE‐cellulose in the final step. The PI inhibited trypsin and chymotrypsin (IC50 = 7.2 and 8.8 μM). Its trypsin inhibitory activity was stable from pH 2 to pH 13 and from 0∘C to 70∘C. The hemagglutinin activity of the hemagglutinin was stable from pH 2 to pH 13 and from 0∘C to 75∘C. The results indicated that both PI and hemagglutinin were relatively thermostable and pH‐stable. The trypsin inhibitory activity was inhibited by dithiothreitol, signifying the importance of the disulfide bond to the activity. The hemagglutinating activity was inhibited most potently by D (+)‐raffinose and N‐acetyl‐D‐galactosamine, suggesting that the hemagglutinin was specific for these two sugars. Both PI and hemagglutinin inhibited HIV‐1 reverse transcriptase (IC50 = 3.2 and 5.5 μM), proliferation of breast cancer cells (IC50 = 9.7 and 3.5 μM), and hepatoma cells (IC50 = 35 and 6.2 μM), with relatively high potencies.
Complex Dynamics in a Growth Model with Corruption in Public Procurement
Authors: Brianzoni Serena , Coppier Raffaella , Michetti Elisabetta
Published: March 2011

We study the relationship between corruption in public procurement and economic growth
within the Solow framework in discrete time, while assuming that the public good is an input in
the productive process and that the State fixes a monitoring level on corruption. The resulting
model is a bidimensional triangular dynamic system able to generate endogenous fluctuations
for certain values of some relevant parameters. We study the model from the analytical point
of view and find that multiple equilibria with nonconnected basins are likely to emerge. We
also perform a stability analysis and prove the existence of a compact global attractor. Finally,
we focus on local and global bifurcations causing the transition to more and more complex
asymptotic dynamics. In particular, as our map is nondifferentiable in a subset of the states
space, we show that border collision bifurcations occur. Several numerical simulations support
the analysis. Our study aims at demonstrating that no long‐run equilibria with zero corruption
exist and, furthermore, that periodic or aperiodic fluctuations in economic growth are likely to
emerge. As a consequence, the economic system may be unpredictable or structurally unstable.
Use of Foscarnet Therapy for EBV Infection following Control of PTLD with Enhancement of Cellular Immunity in a Lung-Transplant Recipient
Authors: Afshar Kamyar , Rao A. Purush , Patel Vipul , Forrester Kevin , Ganesh Sivagini
Published: March 2011

Posttransplant lymphoproliferative disorder (PTLD) is a serious complication following solid organ transplantation with an annual incidence rate of 3–5% in lung-transplant recipients. Pathogenesis indicates a strong association with functional over-immunosuppression and EBV infection. Clinical improvement is generally observed with reduction in immunosuppression intensity alone. We present a case of a 24-year-old woman with EBV-associated PTLD following lung transplant where decreasing the immunosuppression improved PTLD but was ineffective against controlling the EBV infection. Foscarnet in combination with immunoglobulins was successfully administered to cause a remission of the EBV infection. This is the second case reported of a persistent EBV infection after reducing immunosuppression levels and evidence of PTLD remission that required foscarnet for EBV infection control.
Emergency Physician Performed Ultrasound for DVT Evaluation
Authors: Fox John Christian , Bertoglio Kiah Christine
Published: March 2011

Deep vein thrombosis is a common condition that is often difficult to diagnose and may be lethal when allowed to progress. However, early implementation of treatment substantially improves the disease prognosis. Therefore, care must be taken to both acquire an accurate differential diagnosis for patients with symptoms as well as to screen at-risk asymptomatic individuals. Many diagnostic tools exist to evaluate deep vein thrombosis. Compression ultrasonography is currently the most effective diagnostic tool in the emergency department, shown to be highly accurate at minimal expense. However, limited availability of ultrasound technicians may result in delayed imaging or in a decision not to image low-risk cases. Many studies support emergency physiciansas capable of accurately diagnosing deep vein thrombosis using bedside ultrasound. Further integration of ultrasound into the training of emergency physicians for use in evaluating deep vein thrombosis will improve patient care and cost-effective treatment.
Highly Automated Dipole EStimation (HADES)
Authors: Campi C. , Pascarella A. , Sorrentino A. , Piana M.
Published: March 2011

Automatic estimation of current dipoles from biomagnetic data is still a problematic task. This is due not only to the ill-posedness of the inverse problem but also to two intrinsic difficulties introduced by the dipolar model: the unknown number of sources and the nonlinear relationship between the source locations and the data. Recently, we have developed a new Bayesian approach, particle filtering, based on dynamical tracking of the dipole constellation. Contrary to many dipole-based methods, particle filtering does not assume stationarity of the source configuration: the number of dipoles and their positions are estimated and updated dynamically during the course of the MEG sequence. We have now developed a Matlab-based graphical user interface, which allows nonexpert users to do automatic dipole estimation from MEG data with particle filtering. In the present paper, we describe the main features of the software and show the analysis of both a synthetic data set and an experimental dataset.
Swift's Gentleness
Authors: Chudgar Neil
Published: March 2011

Although Jonathan Swift is infamous for the violent physicality of his rhetoric, Gulliver's Travels repeatedly and explicitly insists on the importance of gentle touch, particularly at moments when Gulliver encounters other creatures. This essay argues that such moments are fundamental to Swift's works. Their necessary literalism constitutes a rhetorical ground for the complex structures of Swift's irony, and their insistence on the tangible properties of individual creatures allows readers access to Swift's positive ethics.
"A Great Break in the Common Course of Confession": Narrating Loss in Charlotte Brontë's Villette
Authors: Braun Gretchen
Published: March 2011

This essay suggests that a complex understanding of trauma can significantly explain both the narrative structure and the subject matter of Charlotte Brontë's Villette . The narrative structures attendant on traumatic experience provide a model for understanding Lucy Snowe's silences, repetitions, and evasions in a way that moves past the longstanding critical dichotomy that casts them as either an indication of oppression or a strategy for empowerment and instead explores how they both represent and enact a model of communication that seeks to render accessible experiences and perspectives generally marginalized in both Brontë's contemporary culture and the traditional realist novel.
Mark Twain and the Critique of Philology
Authors: Giancarlo Matthew
Published: March 2011

Mark Twain's life-long interests in language and technology were strongly influenced by his engagement with the German language and the burgeoning science of philology. Drawing from many texts and resources not before studied, this article argues that Twain had a profoundly critical perspective on philology. Consistently in his works philology is presented as both as true science and as a means for imposture and fakery. Thus Twain's critique of philology both exemplifies and exposes a fundamental epistemological quandary of our relation to the past, as well as the violence that results for our desire to give ourselves a "better" history.
"The persuasion of books": The Significance of Libraries in Colonial British Columbia
Authors: Dean Heather
Published: March 2011

In nineteenth-century British Columbia pioneers established libraries and fostered literary activities as part of the colonial project. Colonists believed that such institutions and activities were central to creating and maintaining a successful pioneer society. Victoria's political and cultural leadership as the capital, in fact, used libraries and literary activities generally as instruments of colonial power. This article explores the establishment of libraries and reading rooms in Victoria, the origins of the public library movement in British Columbia, and the impact of libraries and reading material on colonial society.
A Comparison of the Progressive Era and the Depression Years: Societal Influences on Predictions of the Future of the Library, 1895-1940
Authors: Grossman Hal B.
Published: March 2011

This study examines societal influences on predictions of the future of the library from both the Progressive Era (1895-1920) and the Great Depression (1932-40). Predictions from the Progressive Era tend to place the reader at the crest of a long wave of progress, to foresee voluntary cooperation among libraries, and to stress a moral dimension of librarianship. Predictions from the Depression years tend to place the reader at a moment of historical disjunction and to foresee either a centrally planned library system or a future shaped by wonderful advances in science. The ways in which the predictions examined here partook of the dominant sociopolitical ideas of their day underscore the social embeddedness of libraries.
Challenges and Accomplishments in U.S. Prison Libraries
Authors: Lehmann Vibeke
Published: March 2011

This article focuses on the evolution of prison library services in the United States and the changes in the roles and purposes of prison libraries over the last two centuries. The development of standards and guidelines for prison libraries under the leadership of the American Library Association and the American Correctional Association is discussed. The characteristics of the offender population are described as well as how prison libraries have responded to the specific needs of this special user group. The challenges of the unique prison environment are highlighted, especially as they relate to the delivery of library services. Examples of successful library services and programs are included, with descriptions of technology projects, resources for prison library staff, collection development policies, law library services, literacy programs, and resources to assist inmates with the transition back to society.
Books Open Worlds for People Behind Bars: Library Services in Prison as Exemplified by the Münster Prison Library, Germany's "Library of the Year 2007"
Authors: Peschers Gerhard
Published: March 2011

The prison library at the Münster Correctional Facility was named "Library of the Year 2007" by the German Library Association. An examination of this specific library in North Rhine-Westphalia (NRW) provides insight into the operation and services of prison libraries in Germany. This article will hopefully inspire readers to get involved in library work with a social focus and bring attention to the new advocacy organization Prison Library Support Group (Förderverein Gefangenenbüchereien e.V.). Besides opening the door to a world normally closed to the public, this article seeks to sensitize the reader to the microcosm of human experience that exists behind prison walls.
The Effects of Nucleation and Growth on Epitaxy in the CoSi2/Si System
Authors: Gibson J. M. , Bean J. C. , Poate J. M. , Tung R. T.
Published: March 2011

The epitaxial perfection and microstructure in thin CoSi2 (111) (and NiSi2) films on silicon has been examined using transmission electron microscopy, including high resolution cross section techniques. We find that, under ultrahigh vacuum preparation conditions only, genuine single-crystal epitaxy can occur for bothreacted and codeposited CoSi2 films. A unique interfacial defect structure is associated with this epitaxy, in which the silicide films are rotated through 180° about (111) with respect to the silicon substrates. Under less than perfectly clean conditions epitaxial perfection is never obtained for CoSi2. Moreover such perfection has never been attained under any conditions for NiSi2 on Si(111). By studying the evolution of epitaxy and defect structure in thin and thick films we have proposed a model to explain the unique quality of ultrahigh vacuum CoSi2 films. The model invokes a defect pinning mechanism to explain the dominance of the 180°-rotated epitaxy during silicide growth.
Anomalous Bands in the Photoluminescent Spectra from GaAs-(AI,Ga) as Double Heterostructures
Authors: Swaminathan V. , Wagner W. R. , Schumaker N. E. , Miller R. C.
Published: March 2011

In the low temperature (5.5 K) photoluminescent spectra from (Al,Ga)As double heterostructures grown by liquid phase epitaxy (LPE) for laser devices, certain anomalous emission bands higher in energy than the active laye emission but lower in energy than the cladding layer emission are observed. The peak wavelengths and intensities of these anomalous emission bands vary not only from wafer to wafer but also within a given wafer indicating spatial localization of these regions. Photoluminescence measurements on cleaved edges of wafers and on taperetched wafers as well as double-crystal X-ray diffractometry measurements suggest that the anomalous emission bands originate from interfacial regions having different aluminum compositions which are formed between the active and cladding layers presumably as a result of melt carry-over during LPE growth. The integrated photoluminescent intensity of the anomalous emission bands decreases with temperature in the range 75–300 K by nearly two orders of magnitude suggesting the role of some non-radiative process. The spatially localized regions of different aluminum compositions could act as sources and/or sinks for point defects and thus could affect the reliability of devices. Further, their presence would also reflect nonuniformity in the aluminum composition in the active layer.
Structure and Performance of Polycrystalline Thin Film Solar Cells
Authors: Yang Edward S.
Published: March 2011

A review of recent advances in polycrystalline thin film solar cells is presented. A comparison of the fundamental mechanisms and the performance of heterojunction, Schottky barrier, metal-insulator-semiconductor, inversion layer and p-n junction devices is given. The emphasis is placed on devices fabricated by low temperature processes, and the influence of grain boundaries on carrier recombination and transport is discussed.
Metallization for Very-Large-Scale Integrated Circuits
Authors: Ghate P. B.
Published: March 2011

Progress in patterning technologies and computer-aided circuit designs have brought us to the threshold of very-large-scale integrated (VLSI) circuits with 100 000 or more devices to be integrated on a silicon chip. In this paper we review thin film applications in the fabrication of contacts and interconnects for VLSI circuits. Device structures suitable for both bipolar and metal/oxide/semiconductor (MOS) VLSI circuit applications tend to have shallow junction depths and contact areas (silicon-metal interfaces) in the 0.2–0.5 μm and 1–2μm2 ranges respectively; also some of the circuits require Schottky barrier diodes. Consumption of silicon in the contact windows needs to be minimized with the use of silicide layers for siliconmetal contacts. The formation and use of platinum silicide layers for bipolar applications are reviewed. Our observations indicate that the carbon and oxygen present in Czochralski-grown silicon crystals interfere in platinum silicide formationand affect the electrical characteristics of the contacts. The use of barrier layers in VLSI metallization is illustrated. The interdependence of film microstructure, electromigration-induced failures and VLSI interconnection reliability is examined. The integration of a large number of components on a VLSI chip with a single level of interconnections consumes more chip area. Long interconnection paths adversely affect circuit performance. Multilevel interconnections (conductor/insulator/conductor) offer an attractive solution to increase the packing density and circuit performance. The application of PtSi/(Ti: W)/(Al-Cu)/SiO2 /(Ti: W)/A1 film layers in the fabrication of a bipolar VLSI circuit with a minimum feature size of 1.25 μm is illustrated. As the complexity of VLSI circuits continues to grow with micron size device structures, three or more levels of interconnections compatible with shallow junctions on the substrates and complex packaging technologies are required. Areas of concern and desirable features in VLSI metallization are summarized.
Lattice Imaging of Silicide-Silicon Interfaces
Authors: Chen L. J. , Mayer J. W. , Tu K. N. , Sheng T. T.
Published: March 2011

The interfaces of both epitaxial and non-epitaxial silicides and silicon were investigated by the direct lattice imaging method using cross-sectional samples. Non-epitaxial CoSi2 on silicon was observed to have a curved interface. Epitaxial CoSi2 , however, was found to be smooth within a facet. No evidence of an amorphous layer at the interface was obtained.

Epitaxial NiSi2 on Si(001) was found to be heavily faceted. The facets are on {111} and {100} planes with the former more frequently observed. The interface between Si(111) and NiSi2 is also faceted but less so than that for Si(001). The interface is very rough on a large scale. Straight boundary lines corresponding to faceted planes were observed which indicated that the interfaces on an atomic scale were quite smooth. Defect clusters and planar defects were also observed at the interfaces.
In Situ Ultrahigh Vacuum Friction Measurement and Wear Track Analysis of Ion Implanted 304 Stainless Steel
Authors: Pope Larry E. , Follstaedt David M. , Knapp James A. , Barbour J. Charles
Published: March 2011

The dual ion implantation of Ti and C into 304 stainless steel has been found to reduce friction and wear in ultrahigh vacuum (UHV). The implantation treatment producing this result, 4.6 × 1017 Ti/cm2 (180 keV) followed by 2.0 × 1017 C/cm2 (50 keV), produced TiC precipitates dispersed in an amorphous surface layer. Friction and wear track compositions were measured in situ with a scanning Auger microprobe without removing the pin from the track. This treatment decreased the friction coefficient from 1.2 to 0.6–0.8 and the wear track width from 342 μm to 225 pm after 1000 cycles. Relative to unimplanted 304, wear tracks formed in UHV and air on implanted ‘304 had more N and less C. Oxygen and the metallic elements were similar in concentration, except for the presence of implanted Ti. Friction coefficients measured in air were less than those in UHV; track composition suggests that oxides or adsorbed moisture helped lower the friction in air.
Combined Effect of Ion Implantation and Ion Beam Mixing on Metal Surface
Authors: Wei Tian , Tau Peng
Published: March 2011

The article is an account of the development of a new technique to improve the surface properties of materials by ion beam bombardment combined effect of ion implantation and ion beam mixing.

Ti+ ion beam has been used to mix the surface of Cr-deposited on to Fe or to implant Ti+ into the surface of Fe. By comparing the electrochemical properties, it has been shown that the corrosion resistance of Cr-deposited Fe surface mixed with Ti + ion beam is much better than that of Ti+ ion implanted Fe surface, the critical current density Ic and minimum anodic passive current density Im are decreased by one order of magnitude in deacrated 1M CH3 -COONa-CH3 COOH solution (pH 7.3, 25°C). AES and SIMS observation show Nhat the gombined effect of implantation and mixing has been really achieved.
Wear Properties and Surface Structure of Ion Implanted Glassy Carbon
Authors: Yoshida Kazuo , Okuno Kazuhiko , Katagiri Gen , Ishitani Akira , Takahashi Katsuo , Iwaki Masaya
Published: March 2011

Wear properties of Li+, K+, C+, Cl+, and Ti+ implanted glassy carbons (GC) have been studied by wear tests using silicon carbide abrasive paper. It has been found that ion implantation is effective for improving wear resistance of GC. The measurements of Raman spectra revealed formation of an amorphous structure on the surface. Anomalous depth profiles with flat concentration distribution of Li and K atoms were observed by a secondary ion mass spectroscopy (SIMS). In conclusion. the formation of an amorphous structure seems to explain the improvement in wear resistance.
An Ion Beam Simulation of the Swelling of U3Si
Authors: Allen Charles W. , Birtcher Robert C. , Rehn Lynn E. , Hofman Gerard L.
Published: March 2011

Uranium intermetallics are under consideration as possible low-enrichment reactor fuels. These materials divide into two classes with regard to dimensional stability during their service lifetime: those which suffer extreme dimensional growth and those which do not. It has been suggested that the rapid-swelling materials are those that become glassy under irradiation while the low-swelling materials are those that remain crystalline. The structural and dimensional stabilities of U3Si (depleted uranium) have been investigated as a function of temperature duning Kr irradiation by in situ. HVEM observations. Below 550 K, this material becomes glassy during 1.0 MeV Kr irradiation. Prolonged irradiation at 475 K also leads to rapid darkening of the TEM bright field image of the specimen, growth of the initial perforation at rates which far exceed those due to sputtering, and formation of additional thin areas and holes. Irradiation at 615 K does not result in observable image darkening or rapid growth of the initial perforation. After 2×1020 Kr m-2, the crystalline material irradiated at 615 K is stabilized against subsequent ion-irradiation-induced amorphization and growth at 475 K. Similarly, after 2×1020 Kr m-2 at 475 K, the glassy phase persists at 620 K under additional Kr irradiation, and the rapid growth continues. The mechanism of the irradiation-induced growth of the glassy material does not involve gas precipitation but rather may involve deformation by viscous flow assisted by the defects generated during irradiation.
The Effect of Implant Species on the Stability of Ion Implantation Damage
Authors: Jones K. S. , Prussin S. , Venables D.
Published: March 2011

A systematic study of the effect of the chemical species, implanted into silicon, on the stability of the residual damage has been performed. Plan-view and cross-sectional transmission electron microscopy (TEM) studies show that the stability of the end of range damage (category II) defects upon annealing depends dramatically upon the implant species. This is exemplified by the a comparison of 69Ga and 72Ge implants in which a decrease in the dislocation density by over four orders is noted for 69Ga implants compared to 72Ge implants after identical annealing cycles. Additional comparisons of species with similar atomic masses indicate that this destabilizing influence on the dislocation loops by the implant species is related to exceeding the solid solubility of the implanted species. As a result of this dislocation loop destabilization effect complete elimination of the dislocation loops can be realized after relatively short thermal cycling. Evidence is presented indicating that the precipitates which form upon exceeding the solid solubility (category V defects) are dissolving during this enhanced defect dissolution process.
The Promotion of Silicide Formation using a Scanned Silicon Ion Beam
Authors: Williams E. J. , Bithell E. G. , Boothroyd C. B. , Stobbs W. M. , Young R. J. , Cleaver J. R. A.
Published: March 2011

The promotion of silicide reactions at the interface between silicon and a metal overlayer is described, the reactions being initiated by scanned ion beams. The relative effects of low and high energy Si+ and Si2+ beams are discussed and the results of subsequent annealing are compared with those seen when using low energy (5keV) argon ion beams. The implications for the writing of metallisation lines are also noted.
In Situ TEM Observations of Heavy Ion Damage in Gallium Arsenide
Authors: Bench M. W. , Robertson I. M. , Kirk M. A.
Published: March 2011

Transmission electron microscopy experiments have been performed to investigate the lattice damage created by heavy-ion bombardments in GaAs. These experiments have been performed in situ by using the HVEN - Ion Accelerator Facility at Argonne National Laboratory. The ion bcorbardments (50 keV Ar+ and Kr+) and the microscopy have been carried out at temperatures rangrin from 30 to 300 K. Ion fluences ranged from 2 × 1011 to 5 × 1013 ions cm−2.

Direct-inpact amorphization is observed to occur in both n-type and semi-insulating GaAs irradiated to low ion doses at 30 K and room temperature. The probability of forming a visible defect is higher for low temperature irradiations than for room temperature irradiations. The amorphous zones formed at low temperature are stable to temperatures above 250 K. Post implantation annealing is seen to occur at room temperature for all samples irradiated to low doses until eventually all visible damage disappears.
The Effects of Doping and Temperature on the Fermi Level and its Relationship to the Recrystallization Growth Velocity in Ion-Implanted Silicon
Authors: Mosley L. E. , Paesler M. A. , Richard P. D.
Published: March 2011

It has been observed that doping produces an enhancement in the recrystallization growth rate of silicon made amorphous by ionimplantation. This enhancement has been attributed to a shift of the Fermi level with doping. Evidence supporting this is based on the compensating effect of implantation of n- and p-type dopants together. We have previously proposed a model of the recrystallization growth process based on the diffusion of dangling bonds. We suggested that the rate enhancement is due to band bending at the amorphous-crystalline interface produced by doping. We have calculated the change in activation energy for the recrystallization growth velocity for a number of doping concentrations as a function of temperature. The major contribution to the apparent lowering of the activation energy with doping in an Arrhenius plot of the growth velocity versus I/kT is due to the temperature dependence of the Fermi level. Experimental data are compared with the calculated results. In addition differences in the measured growth rates in thermal and laser annealed samples are discussed, with primary emphasis on the lack of a change in the activation energy with doping in the laser annealed case.
Ion Induced Quasicrystalline Transformation in the Al-Cr-Er System
Authors: Lilienfeld David A.
Published: March 2011

The Aluminum-rich end of the Al-Cr-Er ternary system was investigated in an effort to find new quasicrystalline alloys. Composition, dose dependence and substrate temperatures during ion irradiation were varied. A quasicrystal alloy with the Al-Cr intensity pattern was found at low Er content. Another phase was observed that did not index to any known equilibrium structure. This new phase has d spacings and diffraction line intensities which are similar to those of the Al-Li-Cu quasicrystalline phase.
Optical Properties of Picosecond Laser Irradiated Graphite
Authors: Malvezzi A. M. , Reverberi G. , Bloembergen N.
Published: March 2011

We have employed pump-and-probe techniques coupled to ellipsometry to measure the transient complex index of refraction at 1.064 μm of higly oriented pyrolitic graphite (HOPG) interacting with 20 ps, .532 μm laser pulses. When the laser pump fluence exceeds the threshold value for melting, measurements indicate a substantial decrease of both real and imaginary parts of the index of refraction, thus confirming that molten graphite becomes less metallic. Measurements provide also direct evidence of the insensitivity of our picosecond results to evaporation from the irradiated surface.
Time-Resolved and Nicrostructural Studies of Solidification in Undercooled Liquid Silicon
Authors: Lowndes D. H. , Pennycook S. J. , Wood R. F. , Jellison G. E. , Withrow S. P.
Published: March 2011

Nanosecond resolution visible (633 nm) and near-infrared (1152 nm) reflectivity measurements have been used, together with transmission electronmicroscopy (TEM), to study pulsed KrF (248 nm) laser melting and subsequent solidification of thick (190–410 nm) amorphous (a) silicon layers. The measurements cover the entire laser energy density (El) range between the onset of melting (∼ 0.12 J/cm2) and the completion of epitaxial crystallization (∼1.1 J/cm2). Four distinct El-regimes of melting and solidification are found for the 410-nm thick a-Si layers. For El > 0.25 J/cm2, the time of formation, velocity and final depth of “explosively” propagating undercooled liquid layers were measured in specimens that had been uniformly implanted with Si, Ge, or Cu. TEM shows that the “fine-grained polycrystalline Si” produced by explosive crystallization (XC) actually contains large numbers of disk-shaped Si flakes that have largely amorphous centers and are visible only in plan view. The optical and TEM measurements suggest (1) that flakes are the crystallization events that initiate XC, and (2) that lateral heat flow (parallel to the sample surface) must be taken into account in order to understand flake formation. Results of new two-dimensional (2-D) model calculations of heat flow and solidification are presented. These calculations confirm the importance of 2-D heat flow and crystallite growth early in the solidification process. For 0.3 4 < El > 1.0 J/cm2, pronounced changes in both the shape and the duration of the reflectivity signals provide information about the growth of polycrystalline grains; this information can be correlated with post-irradiation plan and cross-section view TEM microstructural measurements.
Interface Temperatures and Temperature Gradients in Silicon During Pulsed Laser Irradiation
Authors: Larson B. C. , Tischler J. Z. , Mills D. M.
Published: March 2011

Nanosecond-resolution x-ray diffraction has been used to measure the interface and lattice temperatures of silicon during rapid, pulsed-laser induced melting and regrowth in silicon. Measurements have been carried out on <100> and <111> oriented silicon using the (100) and (111) reflections to measure the thermal strain during 30 ns, 1.1 J/cm2 KrF laser pulses. The results indicate overheating to be low (< 2 K/m/s) for both orientations with undercooling rates of 5.6 K/m/s and 11.4 K/m/s for the <100> and <111> orientations, respectively. Observations of higher than expected temperature gradients below the liquidsolid interface have been discussed in terms of restricted heat flow under high gradients.
Interface Velocity Transients During Melting of a-Si/C-Si Thin Films
Authors: Tsao J. Y. , Aziz M. J. , Peercy P. S. , Thompson M. O.
Published: March 2011

We report transient conductance measurements of liquid/solid interface velocities during pulsed laser melting of amorphous Si (a-Si) films on crystalline Si (c-Si), and a more accurate, systematic procedure for analyzing these measurements than described in previous work [1]. From these analyses are extracted relations between the melting velocities of a-Si and c-Si at a given interface temperature, and between the temperatures during steady-state melting of a-Si and c-Si at a given interface velocity.
Liquid Mediated Pulsed Laser Processing of Silicon
Authors: Biunno Nicholas , Narayan J. , Singh R. K. , Hofmeister S. K. , Schreiner A. F. , Sito M. L. , Auciello O. H.
Published: March 2011

We have investigated the formation of thin layers of carbides and nitrides by irradiating silicon (100) single crystal immersed in clear organic solvents or liquid ammonia. The liquids were transparent to the excimer laser (λ=308 nm, τ45 ns) used, at energy densities from 0.5 to 3.0 Jcm−2. Most of the laser energy was absorbed by the silicon specimens above a certain threshold to cause melting of the surface to a depth of approximately 250 nm. The pool of liquid silicon reacts with the solvents or ammonia in a saturated high pressure vapor phase for a duration of approximately 200 ns per pulse. The specimens were irradiated with a number of pulses ranging from 1 to 50. The films were then analyzed for structure and composition using TEM, AES, and IR spectroscopy. We report here calculations of laser-solid interactions, microstructure, and properties of the resulting thin films.
Phase Selection in Undercooled Liquids of Pulsed-Laser Melted Alloys
Authors: Follstaedt D. M. , Peercy P. S. , Perepezko J. H.
Published: March 2011

The use of thermodynamic analysis of phase relationships to identify metastable conditions for generating undercooled liquids by pulsed laser melting, and to interpret the resulting microstructures is illustrated from studies of Mn, FeV and TiAl. Phases with simple, disordered structures are found to nucleate and grow within tens of nanoseconds in liquids undercooled by 50–100 K. An extended transformation depth is found in which the stable high-temperature a phase replaces the metastable a phase in FeV due to the heat release from the rapidly forming a phase. The formation of the disordered bcc structure and of a metallic glass in the melt of the ordered compound γ-TiAl indicate that regrowth of this phase is sufficiently slow to generate undercoolings of – 1000 K.
Crystallization and Glass Foriation in Electron and Laser Beam Irradiated Cu-Zr Alloys
Authors: Huang J. S. , Kaufmann E. N. , Wall M. A. , Olsen B. L.
Published: March 2011

Four Cu-Zr alloys, Cu56Zr44, Cu50Zr50, Cu47Zr53, and Cu33Zr67, were surface melted with electron and pulsed laser beams to compare their kinetics of nucleation, growth and glass formation. It was observed that the ease of glass formation increased in the order: Cu33Zr67, Cu47Zr53, Cu56Zr44, and Cu50Zr50. The nucleation and regrowth produced different metastable phases. At the equiatomic composition, the preferred phase is a CsCl-type (B2) BCC structure. As the composition deviates from this, the preferred phase is either orthorhombic or tetragonal with a much larger unit cell not previously reported in the literature. The maximum growth velocity of these metastable phases was found to be about 0.025 m/s. The slow kinetics are responsible for the ease of glass formation in these systems.
Rapid E-Beam Heating for Measuring Thermodynamics of Metastable Materials
Authors: Knapp J. A. , Follstaedt D. M.
Published: March 2011

A line-source electron-beam system has been used to heat thin surface layers of metastable phases at a rate which precludes solid-state transformations to stable phases, thus permitting the observation of melting transitions normally missed with slow heating. A detailed example of a new approach to this method is shown for metastable icosahedral Al-Re and. crystalline Al6Re.
HREM In-Situ Studies of Electron Irradiation Effects in Oxides
Authors: Luzzi D. E. , Marks L. D. , Buckett M. I. , Strane J. W. , Wessels B. W. , Stair P. C.
Published: March 2011

High resolution electron microscope (HREM) studies provide the ability to study desorption and sputtering from the perspective of the analysis of the resultant materials, their structure, composition and atomic registry (orientation with respect to the original,material and the irradiation). This is a neglected facet of surface irradiation effects research, yet it is the most important from the technological point of view. In the current study, surface electron irradiation processes in oxides were studied in-situ in a Hitachi H-9000 HREM operated at incident electron energies of 100–300 keV. It was found that a wide range of processes occur in the HREM which are dependent on the energy and flux of the incident electrons and on the material properties. Both ballistic and electronic irradiation damage was observed and the material responses included surface sputtering, amorphisation, chemical disordering, desorption of O and metal surface layer creation, surface roughening and bulk defect creation.
Cavitation in Unfired Ceramic Sheets by Pulsed Nd:YAG Laser
Authors: Louh Rong-Fuh , Buchanan Relva C.
Published: March 2011

Single shot pulses from a Nd:YAG laser were used to generate different sized holes and patterns in tape-cast ceramic sheets for electronic packaging applications. The ceramic sheets were based on formulations in the BaTiO3 and MgO-Al2O3-SiO2 systems. The single shot laser pulses were targeted using a computer controlled mirror deflection system and a programmed (cavitation) pattern which could readily be modified. Morphology and structure of the drilled holes before and after sintering were examined by SEM. The surface radial temperature profile resulting from the laser pulse was directly mapped using a lacquer thermocoat. Effects of the laser pulse energy and beam spot size on laser/ceramic interactions and cavitation process were also explored.
Excimer Laser Induced Damage in Stressed Polyimide Films Exposed in Air
Authors: Tonyali K. , Jensen L. C. , Dickinson J. T.
Published: March 2011

In earlier work we reported the consequences of simultaneous exposure of polymers to mechanical stress and electron bombardment. In this study we examine the response of highly stressed polyimide films to excimer laser radiation (20 ns pulses @ 248 nm wavelength) in air. The exposed surfaces show evidence of surface and near surface damage, crack initiation, and eventually crack growth over a wide range of applied stress and laser fluence. These results show that the morphology of the stressed material has a significant influence on the resulting damage and suggest that the regions of highest damage are those experiencing the highest local stress. A growth of nodules on the polyimide surface are also observed which are missing when exposed in vacuum.
Ion Beam Modification of Film Stress and the Effectiveness of Thin Film Encapsulants on GaAs
Authors: Haynes T. E. , Picraux S. T. , Lee S. R. , Chu W. K.
Published: March 2011

Ion implantation has been used to modify the initial stress in thin (40 nm) SiO2 films on G a As, and to condition the SiO2-G a As interface to pro mote adhesion. The effectiveness of these implanted films as caps to suppress decomposition of GaAs during rapid thermal processing has been studied, and this provides an indicator of the mechanical stability of the films. Measurements of the initial film stress, as well as stress changes caused by implantation and annealing, have been made to help interpret the implantation results. Our results indicate that ion implantation does not have a strong effect on the performance of thin film SiO2 encapsulants on GaAs.
On the Contacts Formed in Ni-Al-Si System Due to Localized Melting by Means of Rapid Thermal Processing
Authors: Katz A. , Komem Y.
Published: March 2011

Localized rapid melting of an intermediate Al film in the Ni(30nm)/Al(10nm)/<100>n-Si system was successfully carried out by means of rapid thermal processing at temperatures higher than 580°C. This rapid melting resulted in the formation of a unique metal-silicon contact composed of three separated layers and has the following structure: Ni(Al0.5,Si0.5)/Al3 Ni/NiSi / <100>n-Si.
It was found on the basis of quenching treatments after subsequent rapid thermal processings that an eutectic melting initiated at the Al-Si interface at 580°C, propagated towards the Ni layer and then formed a localized melt zone confined mainly to the region of the intermediate Al layer. The formation of the nickel silicides took place at the silicon surface after Ni diffusion through the melt zone, while the Al compounds were formed during a solidification process of the eutectic liquid. The eutectic melting at 580°C led to the decrease of the sheet resistance of the formed films from 3.2 to 2.6 / and to the increase of the Schottky barrier height of the contact from 0.6 to 0.76 eV.
Oxidising Role of Water Vapour in the 250 Kev D+ Induced Radiolysis of Polyimide Kapton-H
Authors: Chaturvedi U. K. , Patnaik A. , Pathak Ramji , Chakraborty R. N. , Nigam A. K.
Published: March 2011

Residual water vapour present in the vacuum system has been observed to play a dominant oxidising role in the 250 keV D+ induced radiolysis of polyimide (Kapton-H). The partial pressure (pp) of water in the vacuum system decreases sharply as the D+ beam impinges the polymeric surface, but soon after, it recovers to its initial value as the accumulated dose increases. Emission of CO2 is observed which has its maximum at a time when the H2O partial pressure is at a minimum. The CO2 level also returns to its original level with time. This complementary variation of CO2 and H2O confirms that absorbed and adsorbed water molecules are radiolysed by the ion beam and initiate oxidation of the radiolytically evolved CO to yield CO2 on and within the ion implanted surface of the polyimide. Further, the small enhancement in the 28 amu peak (N2 + CO), which exhibits no maximum/minimum over the entire implantation time, can be understood in terms of the evolution of N2 from the imide ring as a result of radiolysis of this nitrogen containing polymers.
Interfacial Reactions of Mo with Al: Ion mixing Versus Thermal Annealing
Authors: Ma E. , Brunner A. J. , Workman T. W. , Nieh C. W. , Zhao X.-A. , Nicolet M-A.
Published: March 2011

Interfacial reactions induced by ion beam mixing and furnace annealing in Al/Mo bilayers are investigated. The amount of interfacial ion m'xing, 4Dt, follows a linear dose dependence for irradiation temperatures ≤80 C. Below room temperature, the mixing efficiency, defined as d(4Dt)/dø, is temperature independent, and agrees fairly well with the prediction of the phenomenological model based on chemically biased diffusion in thermal spike. We conclude that thermal spike mixing dominates for Xe irradiation of Al/Mo at low temperatures. The mixing efficiency becomes temperature-dependent above room temperature with an apparent activation enthalpy of about 0.17±0.02eV. A layer of 15–20 at.% Mo forms by ion mixing, while oAl12 Mo forms upon thermal annealing in a nonuniform fashion starting at 500°C. Reaction of Mo with large-grained Al substrates shows the same nonuniform characteristics as in evaporated Al/Mo bilayers, implying a minor role of grain boundary effects. Oxygen gettered in the Mo film could be an important factor that influences the interfacial reaction.
Formation of Metastable Structures and Amorphous Phases in cu-w Alloys Using the Triode Sputtering Technique
Authors: Rizzo H. F. , Tanner L. E. , Wall M. A. , Massalski T. B. , McClanahan E. D.
Published: March 2011

The triode sputtering technique and a “split-target” arrangement were used to produce metastable crystalline and amorphous phases in the Cu-W system under essentially oxygen-free conditions. Large metastable extensions of solid solubility were observed both from the Cu (fcc) and W (bcc) sides of the phase diagram, and a wide range of metallic glass formation was observed, approximately between 30 and 65 at.% W. The thickness of the amorphous Cu-W phase (40–160 pm) that can be deposited without the formation of the metastable bcc phase appears to be dependent on the Cu-W alloy composition. On heating, the crystallization temperature of the amorphous alloys was higher than 350°C. The behavior of the lattice parameter and near-neighbor distance has been studied with x-ray diffraction, showing small positive deviations from an assumed Vegard's Law. Hardness measurements indicate that the metastable crystalline phases are relatively harder than the amorphous phase.