bluuebunny/crossref_metadata_2025_split huggingface dataset:
3-Dimensional Integration Fabricated by Using Seeded Lateral Epitaxial Film on SiO2
Authors: Sasaki N. , Iwai T. , Kawamura S. , Mukai R. , Wada K. , Nakano M. 
Published: March 2011

ABSTRACTSeeded lateral epitaxial laser-recrystallization of silicon film on SiO2 is applied to fabricate 3-dimensional (3-D) integrations: 3-D CMOS 7-stage ring oscillators. Top p-channel Si-gate SOI MOSFET's are fabricated in the seeded recrystallized silicon directly above bottom n-channel Si-gate bulk MOSFET's with insulator in between. The recrystallized silicon at the seed region can be utilized for buried contact to interconnect bottom and top MOSFET's. At the arsenic implantation step to fabricate source and drain of the bottom MOSFET's, ions are not implanted into the seed region to prevent heavy doping and crystal disorder there; otherwise the dopant diffuses laterally and residual crystal disorder disturbs the epitaxial recrystallization. After the laser-recrystallization, the seed region is implanted with phosphorus to interconnect the top and bottom MOSFET's.The Ar+ laser irradiation is performed with a 10 W power, a 50 μm spot size, a 13 cm/s scanning speed and a 13 μm step at 400 °C in air. Propagation delay of 460 psec is obtained for the seven stage 3-D CMOS ring oscillator at a power supply voltage of 17 V for a channel length of 3 μm and a channel width of 18 μm. In the seeded SOI films, grain boundary generation and crystal orientation can be controlled.
Polysilicon Grain Growth by Rapid Isothermal Annealing
Authors: Pinizzotto R. F. , Clark F. Y. , Malhi S. D. S. , Shah R. R. 
Published: March 2011

ABSTRACTone method of reducing the area occupied by a RAM cell is to stack the p- and n-channel devices on top of one another. This “stacked CMOS” structure is a first step towards three dimensional integration. The simplest approach is to use polysilicon as the substrate for the top transistors. This paper describes the results of grain growth studies of samples annealed by rapid isothermal annealing. The temperature varied from 1100 to 1400°C and the anneal time varied from 10 to 480 seconds. TEM was used to examine the microstructure of the material. The grain growth was found to be film thickness limited, i.e. the final grain size was approximately the same as the initial film thickness. As a result, the kinetics of grain growth cannot be described by a simple logarithmic time law. There also is a velocity dependent drag contribution to the growth kinetics that implies impurities play an important role. The interlevel oxide thickness affects grain growth. Thicker oxides lead to faster growth, probably by reducing the heat flow to the silicon substrate. A capping layer was found to have no effect on the grain size. The above results indicate that it is possible to obtain large grains in short times using isothermal annealing. This process may be useful for fabricating stacked polysilicon layers in three-dimensional integrated circuits.
Effects of Grain Boundaries on the Current-Voltage Characteristics of SOI Mosfets
Authors: Fossum Jerry G. , Ortiz-Conde Adelmo 
Published: March 2011

ABSTRACTA physical model that describes the steady-state current-voltage characteristics of field-effect transistors (MOSFETs) fabricated in (poly)silicon-on-insulator (SOI) is described. The model predicts that a single high-angle grain boundary, especially one traversing the channel near the drain, can control the conduction properties of the MOSFET for all (weak-to-strong) inversion conditions in all (linear-to-saturation) regions of operation.
Impurities in Bulk A-Si:H, Silicon Nitride, and at the a-Si:H/Silicon Nitride Interface
Authors: Tsai C. C. , Thompson M. J. , Tuan H. C. 
Published: March 2011

ABSTRACTMajor impurities in a-Si:H are O, C and N, while those in silicon nitride are H, O, C, F, Cl and excess Si. We show that a large reduction in both contaminant impurities and cross contamination achieved in the UHV plasma deposition system yields high purity a-Si:H. The impurity at the a-Si:H/nitride interface is observed to depend strongly on the order of deposition. There is a large amount of nitrogen carried over into a-Si:H when the a-Si:H is deposited after the nitride, Such a compositional asymmetry is likely to lead to an asymmetry in interface characteristics.
The Current Status of Silicon-On-Sapphire and other Heteroepitaxial Silicon-On-Insulator Technologies
Authors: Golecki I. 
Published: March 2011

ABSTRACTThe present understanding of the properties of thin (≤0.6 μm) heteroepitaxial Si films grown on single-crystal bulk and thin film insulators is reviewed. Three areas are covered: (a) as-deposited Si films on bulk insulators, with particular emphasis on sapphire and cubic zirconia (b) post-growth processing methods to reduce the defect concentration and compressive strain in such Si films and (c) the growth and properties of monocrystalline insulating films on bulk Si and of Si on such films. The desired characteristics of the insulating material are given, and it is shown that the mismatch in thermal expansion coefficients between the insulator and Si dominates the properties of heteroepitaxial Si films. Present and future areas of application for Si-on-insulator technologies are briefly described, and directions for further studies are proposed.
Attempts to Apply Thin Film Transistors to Electroluminescent Displays
Authors: Miller M. Robert 
Published: March 2011

ABSTRACTThe objectives of the two programs described here were to develop fabrication processes for flat panel displays using an active matrix of thin film transistors (TFT) behind an electroluminescent (EL) display medium. The programs were carried out under ERADCOM contracts DAAB07-76-C-0027 with Westinghouse R&D Center and DAAB-07-77-C-0583 with Aerojet Electrosystems Company. The huge amount of information about the processes and technology generated through the efforts of capable and dedicated people who worked on these programs was, in spite of everything, not enough to achieve the stated objectives. The fabrication processes developed did not result in repeatable, reliable display devices. The solutions applied to one set of problems tended to uncover new problems previously unseen, but this continual problem solving process probably generated more information about the technology than results from many programs in which the goals are achieved. The improved understanding of TFT processes and applicability is the subject of this report.
Characterization of CMOS Devices in 0.5-μm Silicon-On-Sapphire Films Modified by Solid Phase Epitaxy and Regrowth (Spear)
Authors: Vasudev P.K. , Mayer D.C. 
Published: March 2011

ABSTRACTComplementary Metal-Oxide-Semiconductor (CMOS) devices and circuits with minimum feature sizes of about 1 μm were fabricated in 0.5-μm-thick epitaxial Silicon-On-Sapphire (SOS) films. The films were modified by ion implantation and subsequent solid phase recrystallization processes which reduced the total microtwin concentrations in the Si layers by more than a hundredfold, while increasing electron and hole channel mobilities between 40 to 50%. Leakage currents were reduced by over 2 orders of magnitude, while drive currents and subthreshold slopes showed significant improvements over as–grown SOS films. Propagation delays of less than 80 psec were obtained for CMOS/SOS inverters with Leff = 0.6 μm.
Hydrometallurgical Application of a Novel Porous Resin
Authors: Unger Peter D. , Rohrbach Ronald P. 
Published: March 2011

ABSTRACTThe technology to manufacture rigid, highly porous materials of very low density that are suitable for use in a wide range of industrial applications has recently been developed in this laboratory. These materials, derived from naturally occurring polymers, have many useful physical characteristics including very large pore volume, pore size distribution in a useful range, and high surface area. These characteristicsw, hen combinedw ith their robust mechanicals trength, make them potentially useful as support matrices for various complexing agents. One demonstrated application of this material is as a polymeric carrierfo r selective liquid metal extractants in hydrometallurgicalp rocesses. We have successfully impregnated our porous matrix with several selective metal extractants, and demonstrated retention of the basic metal binding properties of the immobilized agent. Results of bench scale pilot studies using a copper selective impregnated resin indicate excellent capacity, and good selectivity and extraction/elution kinetics.
Direct Colorimetric Detection of Virus by a Polymerized Bilayer Assembly
Authors: Charych Deborah H. , Nagy Jon O. , Spevak Wayne , Ager Joel , Bednarski Mark D. 
Published: March 2011

ABSTRACTScreening and detecting virus by receptor-ligand interactions presents an important challenge in medical and environmental diagnostics, and in drug development. We have developed a direct colorimetric detection method based on a polymeric bilayer assembly. The bilayer is composed of a self-assembled monolayer of octadecyl siloxane and a Langmuir-Blodgett layer of polydiacetylene. The polydiacetylene layer is functionalized with receptor-specific ligands such as analogs of sialic acid. The ligand serves as a molecular recognition element, while the conjugated polymer backbone signals binding at the surface by a chromatic transition. The color transition is readily visible to the naked eye as a blue to red color change and can be quantified by visible absorption spectroscopy. The color transition can be inhibited by the presence of soluble inhibitors. Raman spectroscopic analysis shows that the color transition may arise from binding induced strain on the material resulting in bond elongation and conjugation length reduction.
Cell Function on Substrates Containing Immobilized Bioactive Peptides
Authors: Dee Kay C , Andersen Thomas T. , Bizios R. 
Published: March 2011

AbstractAdhesion, proliferation and motility of bovine pulmonary artery endothelial cells and of rat calvarial osteoblasts were examinedin vitroand on glass surfaces modified with immobilized bioactive peptides. The peptides Arginine-Glycine-Aspartic Acid-Serine (RGDS), Arginine-Aspartic Acid-Glycine-Serine (RDGS), and Tyrosine-Isoleucine-Glycine-Serine-Arginine-Glycine (YIGSRG) were covalently bound to aminophase glass. The results of this study showed that modification of the substrate surface with immobilized peptides affected each cell line in different ways. Incorporation of this knowledge in the design of implant materials could result in biomaterials which promote and/or sustain a number of desirable cellular functions at the tissue-implant interface.
Osteoblast Adhesion on Biodegradable Polymer Substrates
Authors: Ishaug Susan L. , Yaszemski Michael J. , Bizios Rena , Mikos Antonios G. 
Published: March 2011

AbstractWe have investigated the adhesion of rat osteoblasts on biodegradable poly(α-hydroxy ester) films as an in vitro model of bone regeneration. Osteoblasts cultured on poly(L-lactic acid), poly(DL-lactic-co-glycolic acid) copolymers, and poly(glycolic acid) films for 14 days grew with rates comparable to those observed for tissue culture polystyrene and retained their phenotype as expressed by activity of alkaline phosphatase and collagen synthesis.
The Development of an In Situ Assay for bFGF Release
Authors: Hobbs S. K. , Periolat L. M. , Cima L. G. , Nugent M. , Leunig M. , Jain R. K. 
Published: March 2011

AbstractThere is a need for an in situ assay to quantify tissue reactivity to sustained release of bFGF to better understand and control growth factor-induced angiogenesis. To this end we have adapted the alginate/heparin-sepharose release system for use in the mouse dorsal skinfold chamber. A mathematical model was used to predict the time dependence of bFGF release as a function of bFGF loading, heparin concentration, and device geometry. The model predictions agreed well with previously reported in vitro data. In vivo studies to correlate blood vessel growth as a function of release rate are in progress.
Development of a Collagen-Gag Copolymer Implant for the Study of Tendon Regeneration
Authors: Louie L. K. , Yannas I. V. , Spector M. 
Published: March 2011

AbstractFollowing injuries resulting in a gap, tendons generally do not heal sufficiently because the defect does not fill with reparative tissue, or the resulting scar tissue is not functionally adequate. The objective of this study was to engineer a collagen-GAG (CG) copolymer to facilitate tendon regeneration. Previous work in our laboratory using similar porous resorbable analogs of extracellular matrix have led to regeneration of skin and peripheral nerve.Matrices with controlled pore structure were produced by adapting the manufacturing technique developed in our laboratory for grafts with cylindrical geometry. CG suspensions contained within silicone elastomer tubes were frozen and lyophilized in a controlled manner. Quantitative optical microscopy was used to determine the percent porosity, average pore size, and pore orientation of the matrices.The CG matrices, formed in silicone elastomer tubes, 3.8 mm in diameter, had average pore sizes ranging from 20 to 150 μm. his range of pore sizes was comparable to that obtained previously using a diameter of 1.5 mm.1The average pore size did not appear to be strongly dependent on the tubing diameter. The homogeneity of the pore structure and the pore channel orientation could be controlled by adjusting the temperature of the bath used for freezing the CG suspension and the velocity with which the graft was immersed into the coolant bath.
Temperature- and pH- Sensitive Hydrogels for Controlled Release of Antithrombotic Agents
Authors: Brazel Christopher S. , Peppas Nicholas A. 
Published: March 2011

AbstractPolymeric hydrogels capable of reversible swelling with changes in environmental temperature and pH were synthesized and studied as matrix systems capable of controlled release of antithrombotic drugs to the site of a blood clot. Monomers N-isopropylacrylamide (NIPAAm) and methacrylic acid (MAA) were chosen for the temperature- and pHdependent swelling characteristics of their polymers, respectively. Equilibrium swelling studies were performed as functions of pH and of temperature, and kinetic swelling studies were performed on the thermally responsive gels as a function of time after the gel was subjected to a step-change in temperature. Experimental results indicate that P(NIPAAmco- MAA) hydrogels can be synthesized so that they are either pH- or temperaturesensitive, depending upon the composition of the network. The pure PNIPAAm gels showed a lower critical solubility temperature (LCST) of around 32°C, below which the gel was in its swollen state, and above which the gel collapsed. As the amount of methacrylic acid in the gels was increased, the degree of swelling in deionized water decreased and the temperature sensitivity was lost. The hydrogels containing MAA displayed a transition in swelling behavior between pH 4 and 6. The mesh sizes of the hydrogel networks were calculated from the results of the swelling studies by Flory-Rehner theory. A kinetic experiment on the temperature-sensitive pure PNIPAAm hydrogel showed that the polymer network collapsed rapidly upon temperature changes across the LCST.
The Impact of Formulated Interleukin-2 / Delivery Device Surface Interactions on Bioefficacy
Authors: Tzannis Stelios T. , Przybycien Todd M. , Hrushesky William J. M. , Wood Patricia 
Published: March 2011

AbstractThe interactions between a therapeutic protein and the surfaces of a delivery device may play a pivotal role in the efficacy of a recombinant protein-based biologic therapy program. Protein adsorption may induce conformational changes and aggregation, resulting in the inactivation of the protein of interest and even malfunction of the delivery device itself. We studied the interactions of formulated interleukin-2 (IL-2) with the surfaces of a commonly used pump-based delivery system at 37°C over a 24-hour period. Delivered protein concentration and bioactivity assays were performed at intervals in order to quantitate the impact of exposure time. Adsorption to the catheter tubing walls resulted in 20 to 30% reduction in the concentration of delivered IL-2 relative to the initial concentration. After 2 hours of operation, delivered IL-2 bioactivity levels fell to -10% of the initial activity levels. These activity losses were accompanied by a significant decrease in the protein's helical content, as monitored by circular dichroism spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy indicated that adsorbed IL-2 had non native secondary structure contents. We hypothesize that surface-mediated IL-2 denaturation is responsible for the majority of the observed activity losses
Characterization of a Polyanhydride Series by Ftir
Authors: Kreitz Mark R. , Pekarek Kathleen J. , Mathiowitz Edith 
Published: March 2011

AbstractUsing Fourier-transform infrared (FTIR) spectroscopy we have characterized a polyanhydride copolymer series composed of various ratios of the diacids 1,3-bis(p -carboxyphenoxy)propane (CPP) and sebacic acid (SA). Typical peaks corresponding to the aliphatic-aliphatic (SA-SA), aromatic-aliphatic (CPP-SA), and aromatic-aromatic (CPP-CPP) diads were found in the 1820- 1710 cm−1 wavenumber range. Further peaks corresponding to the SA-SA diads were identified in the fingerprint region at 1382, 1360, 1307, and 1286 cm−1. These peak characterizations facilitate identification of bond distribution in the CPP-SA copolymer as well as other polyanhydride copolymers, and correlate well with previously presented information obtained with nuclear magnetic resonance (NMR) spectroscopy and X-ray powder diffraction.
Use of Porous Bone Mineral to Increase Bone Density
Authors: Boyne Philip J. 
Published: March 2011

Abstract:The amount of bone density in a metal implant recipient site markedly effects the success of the implant and the prosthesis. Therefore mechanisms designed to enhance bone density are necessary. Porous bone mineral (BioOss) was used in this study to demonstrate the ability of this product to be slowly resorbed and remodelled, and to enhance in the remodelling process of the amount of calcified bone matrix available for reception of any subsequent placed prosthesis. Further research on the effect of functional prosthesis on the osseous matrix and the long term effect of function on the increase bone matrix is needed.
The Role of Hepatotrophic Stimulation in Heterotopic Hepatocyte Transplantation
Authors: Kaufmann P.-M. , Uyama S. , Sano K. , Mooney D. , Vacanti J. P. 
Published: March 2011

AbstractIn the future, the development of methods for transplantation of large hepatocyte numbers could provide an alternative to the established liver and split liver transplantation. The use of three dimensional prevascularized polyvinyl alcohol (PVA) scaffolds have allowed hepatocyte transplantation equivalent to a whole liver mass. This study was designed to determine if a portacaval-shunt (PCS) or a 70% hepatectomy (70% HE) enhanced engraftment and proliferation of transplanted hepatocytes in heterotopic locations.Male Lewis rats served as both donors and recipients, respectively. PVA-sponges were implanted as matrices for the transplanted hepatocytes. Recipient animals were divided into four groups. All groups received transplantation of 5×107 Hepatocytes (HCTx). In addition, group A received 70% HE, group B received a PCS plus 70% HE whereas group D received PCS. Group C as a control, received only HCTx. Quantitative morphometric analysis of hepatocyte area was performed on day 0, 3, 7 and 14 after transplantation. BrdU staining was performed to study DNA-Synthesis in the graft on day 3 and 14.PCS alone and in combination with a partial hepatectomy led to significantly greater cell area one week after transplantation compared to the partial hepatectomy alone. 70% HE resulted in significantly larger cell area than the controls. At two weeks after transplantation, these significant differences persisted with the exception of Group A and C results which were not significantly different. On day 3, BrdU staining revealed a significantly higher DNA synthesis rate in Groups A and B compared to Group C. On day 14, no statistically significant differences in levels of DNA synthesis could be observed.We conclude that hepatocytes can be successfully transplanted into PVA-devices. Engraftment and proliferation can be significantly enhanced by using portacaval shunt and partial hepatectomy as hepatotrophic stimulation.
Controlled Drug Delivery to the Joints by Enzymatically Degradable Microspheres
Authors: Brown Kimberly E. , Shao Wen , Bathon Joan , Leong Kam W. 
Published: March 2011

AbstractAn intra-articular polymeric controlled release system was developed that is tailored to, and responsive to, the intensity of joint inflammation. Microspheres composed of the naturally occurring polyelectrolytes, gelatin and chondroitin sulfate, were synthesized by complex coacervation and the kinetics of release of encapsulated 14C-catalase was evaluated in vitro in the presence of inflammatory and non-inflammatory human joint fluids. The relative activity of gelatinase, a metalloprotease enzyme, was quantified in each of the joint fluids. Rate of degradation of the microspheres, and consequent release of 14C-catalase, was found to parallel the relative gelatinase activities in the joint fluids. Furthermore, various methods of crosslinking were found to affect the kinetics of microsphere degradation in the fluids. A catalase loading level of up to 28% was achieved, and the encapsulated catalase was found to retain up to 58 % of its biological activity.
The Erosion Properties of Polyanhydrides
Authors: Shieh Lisa , Göpferich Achim , Langer Robert 
Published: March 2011

AbstractBioerodible polymers play an important role in parenteral drug delivery. They combine the advantage of controlling drug release and being absorbed by the body after fulfilling their task. The mechanism which controls drug release is the erosion of polymer bulk. In order to understand and control the release it is, therefore, essential to know the erosion mechanism of a biodegradable polymer. We found that the polyanhydrides obey a distinct erosion pattern. An erosion zone (the region where material loss occurs) moves from the surface to the center of the discs. The monomers of which these copolymers are composed also seem to play an important role in degradation and erosion.
The Decomposition of Methyltrichlorosilane: Studies in A High-Temperature Flow Reactor
Authors: Allendorf Mark D. , Osterheld Thomas H. , Melius Carl F. 
Published: March 2011

AbstractExperimental measurements of the decomposition of methyltrichlorosilane (MTS), a common silicon carbide precursor, in a high-temperature flow reactor are presented. The results indicate that methane and hydrogen chloride are major products of the decomposition. No chlorinated silane products were observed. Hydrogen carrier gas was found to increase the rate of MTS decomposition. The observations suggest a radical-chain mechanism for the decomposition. The implications for silicon carbide chemical vapor deposition are discussed.