bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilization of Protein on Silanized Orthopedic Biomaterials
Authors: Puleo D. A. 
Published: March 2011

AbstractWe have begun to examine methods for biochemically modifying orthopedic biomaterials by covalently immobilizing peptides, proteins, and enzymes. The surfaces of Co-Cr-Mo samples were first silanized using γ-aminopropyltriethoxysilane (APS), which interacts with surface hydroxyl moieties. Derivatization of biomaterial samples with solutions of APS in acetone produced a concentration-dependent number of reactive NH2 groups. The silane layers became unstable and were easily disrupted at concentrations above 2% APS. The enzyme, trypsin, was then coupled to the alkylamine-derivatized samples by formation of Schiff's base linkages via glutaraldehyde. Enzymatic activity of trypsin-conjugated Co-Cr-Mo samples was quantified by determining cleavage of the substrate BAEE. Both alkoxysilane-treated and untreated samples bound trypsin in an active state. When treated with 5 M guanidine hydrochloride to elute noncovalently bound protein, however, nearly all of the trypsin was removed from or rendered inactive on samples either not treated with APS or derivatized with low (<0.5%) concentrations. On the contrary, 1 and 2% APS-treated samples retained appreciable enzyme activity. Approximately 27 and 35% residual trypsin activity was measured on the 1 and 2% APSderivatized Co-Cr-Mo samples, respectively. Active trypsin remained immobilized on the APS-derivatized substrates when at least 35 free amino groups per nm2 of nominal surface area were available for protein coupling.
Hydroxyapatite Coatings of Varying Crystallinity
Authors: Maxian Suzanne H. , Liesch Janice B. , Tiku Moti L. , Zawadsky Joseph P. , Dunn Michael G. 
Published: March 2011

AbstractQuestions remain as to the integrity of hydroxyapatite (HA) coatings on orthopaedic implants and the possibility of failure at the coating/implant interface in vivo. Previous investigations of resorbable HA coated implants showed bone bonding strengths equal to non-resorbable HA coated surfaces in interference fit surgical model. If the concept of a resorbing coating will alleviate concerns of interface failure, further investigation as to the mode of coating resorption and the cellular events at the interface are required. The effect of coating these implants with Matrigel, as a means to enhance bone cell attachment and growth was studied. Fibroblast cell behavior on resorbable, non-resorbable HA coated and uncoated rough titanium implants were studied at 4 and 24 hours for attachment and spreading. Postnatal rat calvarial cell attachment, growth and morphology studies were also performed on these three implants and on tissue culture plates with and without Matrigel at 2, 7, and 10 days. Resorbable HA coatings showed greater surface activity and cell spreading, but not greater cell attachment at 4 and 24 hours. Greater alkaline phosphatase production per cell was seen on Matrigel coated tissue culture plates than uncoated wells. Cytoplasmic processes similar to osteocytic canalicular networks were seen. Matrigel coating on the three types of implants showed slightly greater alkaline phosphatase production of cells than without Matrigel coating.
Control of Pore Size and Morphology in Collagen Microspheres
Authors: Maffia Gennaro J. 
Published: March 2011

AbstractCollagen microspheres are used to immobilize mammalian and hybridoma cells in commercial cell culture in a continuous fluidized bed bioreactor. One advantage of this technology is the high cell densities and the resulting high reactor volume productivity. Cell densities have exceeded 108 cells per milliliter of reactor volume in steady state culture of CHO cells. The microsphere is manufactured in a multi-stage batch process that initially involves pretreating insoluble, Type I bovine hide collagen to remove fats, triglycerides and any soluble compounds. The collagen fibers are then milled and dispersed in an acid solution. Water to collagen ratios of 500/1, mass basis, have been achieved. Stainless steel weighting material is blended in the collagen dispersion in order to control the specific gravity. The dispersion is cast into droplets which are in turn frozen, thermally soaked, lyophilized, fractionated by terminal velocity, crosslinked and finally sterilized. The morphology and pore size are created during the soaking phase, wherein the completely frozen collagen dispersion is partially melted to provide a mobile phase for the collagen fibrils to rearrange. In their dispersed form, collagen fibrils have additional uses in separation and purification due to the ability to precisely control the swelling and collapsing by pH, surface area and concentration.
Design of Bioerodible Devices with Optimal Release Characteristics
Authors: Zygourakis Kyriacos 
Published: March 2011

AbstractThe development of a computational tool to design bioerodible devices with optimal release characteristics is presented. This computational tool uses cellular automata and discrete iterations to model and simulate the release of bioactive agents (drugs) from bioerodible matrices. The simulations can accurately model surface erosion processes in multicomponent systems of arbitrary geometry and with different dissolution rates for each component. Simulation results are analyzed to show how the overall release rates are affected by the intrinsic dissolution rates, drug loading and the dispersion of the drug in the bioerodible matrix. Heterogeneities in the structure of the bioerodible matrix that can lead to local variations of erosion rates are also considered. A strongly nonlinear dependence of release rates on drug loading and dispersion is obtained and the effects of matrix heterogeneities are elucidated. Finally, guidelines are presented for screening of alternatives to minimize the development effort and experimentation required for designing devices with desired release characteristics.
Using Molecular-Beam Mass Spectrometry to Study the Pecvd of Diamondlike Carbon Films
Authors: Graff I.B. , Pugliese R.A. , Westmoreland P.R. 
Published: March 2011

AbstractMolecular-beam mass spectrometry has been used to study plasma-enhanced chemical vapor deposition (PECVD) of diamondlike carbon films. A threshold-ionization technique was used to identify and quantify species in the plasma. Mole fractions of H, H2, CH4, C2H2, C2H6 and Ar were measured in an 83.3% CH4/Ar mixture at a pressure of 0.1 torr and a total flow of 30 sccm. Comparisons were made between mole fractions measured at plasma powers of 25W and 50W. These results were compared to measured concentration profiles and to film growth rates.
Mass Spectrometric Analysis of a High Pressure, Inductively Coupled Plasma During Diamond Film Growth
Authors: Greuel Peter G. , Yoon Hyun J. , Ernie Douglas W. , Roberts Jeffrey T. 
Published: March 2011

AbstractDetermination of the gas phase composition at or near a substrate surface during plasma assisted chemical vapor deposition presents a challenging problem. The species located at a growing surface include highly reactive radicals which are difficult to detect in atmospheric plasma conditions. A system has been designed which consists of an inductively coupled rf plasma reactor linked to a quadrupole mass spectrometer (QMS) via a supersonic convergent-divergent nozzle. Differential pumping in the transient stages allows the plasma chamber to be operated at or near atmospheric pressures, while facilitating the detection of reactant species present in the growth boundary layer with the QMS.
Gas-Phase and Surface Decomposition of Tris-Dimethylamino Arsenic
Authors: Xi Ming , Salim Sateria , Jensen Klavs F. , Bohling David A. 
Published: March 2011

AbstractGas phase and surface decomposition reactions of a novel arsenic precursor tris- (dimethylamino) arsenic (DMAAs) have been studied. Optical fiber-based Fourier transform infrared spectroscopy was used to monitor, in situ, the gas-phase pyrolysis of DMAAs. Homolysis of the arsenic-nitrogen bond with formation of dimethylamine radicals was identified as the key gas-phase reaction pathway. Formation of methylmethyleneimine from reactions with the decomposition products was directly observed. Surface decomposition of DMAAs on GaAs(100) was investigated by low energy electron diffraction and temperature-programmed reaction under ultra-high vacuum conditions. DMAAs adsorbed onto GaAs(100)-(4x6) was found to decompose with 100% efficiency and two surface reaction pathways were identified. The first reaction channel was homolysis of the arsenic-nitrogen bond with formation of dimethylamine radicals, whereas the second pathway involved a β-hydrogen transfer.
Study of Silicon Incorporation in GaAs Movpe Layers Grown With Tertiarybutylarsine
Authors: Redwing J.M. , Kuech T.F. , Simka H. , Jensen K.F. 
Published: March 2011

AbstractMOVPE growth experiments have been used to evaluate the role of gas phase and surface chemistry in the silicon doping of GaAs films grown using SiH4 and Si2H6 dopant sources and tertiarybutylarsine (t-C4H9AsH2 or TBAs) as the Group V source. The use of TBAs with SiH4 results in a greater Si doping efficiency and weaker dependence on growth temperature than is typically observed with AsH3. Gas phase pyrolysis studies combined with reactor residence time experiments indicate that heterogeneous chemistry is responsible for this enhanced Si doping process. TBAs has much less of an effect on Si incorporation from Si2H6, a doping process controlled by homogeneous Si2H6 chemistry. Increased Si doping from Si2H6 with TBAs can be attributed to contributions from the enhanced doping efficiency of SiH4, a product of Si2H6 decomposition. The influence of TBAs on SiH4 doping chemistry was found to improve the doping uniformity of GaAs films grown in our reactor, from +/-12% for films grown with AsH3to +/-5% for TBAs-based material.
Preparation and Evaluation of Erbium Tris(Amide) Source Compounds for Erbium Doping of Semiconducting Materials
Authors: Rees William S. , Lay Uwe W. , Greenwald Anton C. 
Published: March 2011

AbstractRare earth elements are important as dopants in the preparation of semiconductors, particularly for temperature-independent optical devices. The compound Er{N\Si(CH3)3]2}3 has been demonstrated to be a suitable source compound for erbium doping of semiconducting materials. Further investigations of this and related compounds have been carried out. New compounds have been characterized by 1H NMR, FTIR, TGA and elemental analysis techniques. Vapor pressures and decomposition profiles have been examined for these compounds.
Growth of InAs and (InAs)1(GaAs)l Superlattice Quantum Well Structures on GaAs by Atomic Layer Epitaxy Using Trimethylindium-Dimethylethylamine Adduct
Authors: Ohtsuka Nobuyuki , Ueda Osamu 
Published: March 2011

AbstractAtomic layer epitaxy (ALE) of InAs has been developed using trimethylindium-dimethylethylamine adduct (TMIDMEA) as a novel In source. Distinct self-limiting growth of InAs was successfully carried out over a wide temperature range from 350°C to 500°C because of the high thermal stability of TMIDMEA. The possible growth temperature range for ALE-InAs was extended by using TM1DMEA. These results lead us to conclude that the use of TMIDMEA enables us to grow InAs/GaAs heterostructures at a single growth temperature. Using this technique, (InAs)1(GaAs)l short period superlattice (12 periods) quantum-well structures were grown on a GaAs(100) substrate at 460°C. A photoluminescence peak at 1.3 µm was observed in these structures at room temperature.
The Surface Chemistry of CdTe Mocvd
Authors: Liu Wen-Shryang , Aupp Gregory B. 
Published: March 2011

AbstractTemperature programmed desorption (TPD) studies in ultra high vacuum revealed that diethyltellurium (DETe) and dimethylcadmium (DMCd) adsorb weakly on clean Si(100) and desorb upon heating without decomposing. These precursors adsorb both weakly and strongly on CdTe(111)A, with DMCd exhibiting the stronger interaction with the surface than DETe. Dimethylcadmium partially decomposes to produce Cd adatoms; a large fraction of the excess Cd atoms desorb upon heating. In contrast, DETe desorbs without decomposing, suggesting that the rate limiting step in CdTe MOCVD on CdTe(111)A is surface decomposition of the tellurium alkyl.
Selective Deposition of ZnS Thin Films by KrF Excimer Laser on Patterned Zn Seeds
Authors: Yamane K. , Murahara M. 
Published: March 2011

AbstractThe patterned Zn nucleation and the ZnS growth onto the Zn seeds on a thermal oxidized silicon substrate was demonstrated at room temperature with the excimer laser chemical vapor deposition method.The formation of ZnS films was realized by the method based on the two—step process consisting of the nucleation and the subsequent ZnS growth. In the nucleation, a gaseous dimethylzinc was sealed in a reaction chamber and was then evacuated immediately. Then, the substrate surface which was uniformly adsorbed by dimethylzinc molecules was exposed with a single shot irradiation of a patterned KrF laser; Zn seeds were created only on the irradiated parts by a photodecomposition. And the subsequent growth of ZnS was performed by the parallel or perpendicular irradiation methods. As a result, in the perpendicular irradiation method, the high selectivity and crystallinity of the film were performed by irradiating the whole substrate surface with very low fluence of the KrF laser such as 3 mJ/cm2.
Vapor Deposited Ag2S Films as High Resolution Photoregistering Materials in The Infrared Region
Authors: Eneva J. , Kitova S. , Panov A , Haefke H. 
Published: March 2011

AbstractAg2S as a narrow band gap semiconductor is appropriate for photoimaging in the infrared (IR) region. Co-evaporation of Ag and S from two separate sources was used for preparing of thin Ag2S films with different Ag/S ratio. Gelatine subbed glass plates were used as substrates. The structure of the films obtained was examined by transmission electron microscopy and electron diffraction. The effects of chemical composition, film thickness and processing conditions on the photographic parameters were studied.It is shown that after appropriate processing thin Ag2S films with stoichiometric composition can. be successfully used as high resolution (1600 lines/mm) photographic materials in the IR region.
First Principles Study of Aluminum Deposition on Hydrogenterminated Si(100) Surface
Authors: Sosa Carlos 
Published: March 2011

AbstractThe deposition of Aluminum on Si(100) surface has been investigated using density functional methods. This has been accomplished by adoption of a Si9H16 cluster to model the H terminated Si(100) 1XI surface and Si9H15 cluster to model the surface with an unpaired electron. The predicted NLSD dissociation energy for the Si9H16 → Si9H15 + H is 86.3 ± 2.0 Kcal/Mol. This is in agreement with previous theoretical calculations on similar systems.
Gasdynamics and Chemistry in The Pulsed Laser Deposition of Oxide Dielectric Thin Films
Authors: Hastie John W. , Bonnell David W. , Paul Albert J. , Schenck Peter K. 
Published: March 2011

AbstractIn the context of “chemistry and its effects on film quality,” we and a number of other research groups have developed spectroscopic and modeling approaches to better define the pulsed laser deposition process. An overview of these approaches is given here, using the results of recent work performed in our laboratory on the oxide dielectric systems of BaTiO3 and PbZr0.53Ti0.47O3(PZT).
Vaporization Chemistry of Organoaluminum Precursors to Ain
Authors: Crocco Paul D. , Hudson John B. , Wang Yi , Interrante Leonard V. 
Published: March 2011

AbstractWe have used the technique of molecular beam mass spectrometry, with time of flight measurement, to study the vaporization of two organoaluminum precursors to AIN. The compounds studied were the isomers (CH3)3Al·NH3 (I) and (CH3)3N·AIH3 (II). Compound I was synthesized in house by reaction of (CH3)3Al with NH3. Compound II was obtained commercially. Mass spectrometric measurements of Compound I indicated a room temperature vapor pressure below 1 Torr, and slow decomposition at room temperature to yield CH4 and a solid product, identified as the trimer, [(CH3)2AlNH2]3, as well as possible concentrations of the corresponding monomer and dimer. Similar measurements on Compound II indicated partial decomposition to metallic aluminum and gaseous trimethylamine and hydrogen.
Excimer Laser Interactions with Ptfe Relevant to thin Film Growth
Authors: Dickinson J.T. , Norton M.G. , Shin J.-J. , Jiang W. , Langford S.C. 
Published: March 2011

AbstractRecently, thin films of polytetrafluroethylene (PTFE) have been grown using pulsed laser ablation of TeflonTM at 266 nm.1,2 To provide further insight into the growth mechanisms we have examined the neutral and charged particle emissions generated in vacuum by 0 - 3 J/cm2 pulses of 248 nm radiation incident on solid PTFE. Measurements include quadrupole and time-of-flight mass spectroscopy. We find in addition to the neutral monomer (C2F4), copious emissions of highly reactive neutral and charged radicals, e.g., CF2, CF3, CF, F, and Cx. A careful analysis of the fluence dependence of these products provides definitive evidence that their precursors are generated by a thermally driven unzipping reaction. Models for the production of the radical species with the observed energies (several eV) involving gas phase processes are presented. Implications for improving PTFE thin film growth will be discussed.
Diethyldiethoxysilane as a New Precursor for SiO2 Growth on Silicon
Authors: Wise Michael L. , Sneh Ofer , Okada Lynne A. , Dillon Anne C. , George Steven M. 
Published: March 2011

AbstractDiethyldiethoxysilane (DEDEOS) is a potential single molecular precursor for SiO2 growth. Additionally, DEDEOS may be applicable in a deposition scheme that will allow precise atomic layer control of SiO2 film thicknesses. Deposition of SiO2 on silicon using DEDEOS was studied in three regimes. In the first regime, the adsorption and decomposition of DEDEOS were studied using temperature-programmed desorption (TPD) and Fourier-transform infrared spectroscopy (FTIR) under UHV conditions. TPD and FTIR results indicated that DEDEOS deposits ethyl and ethoxy species on the surface which decompose by a β-hydride elimination mechanism. In the second regime, step-wise SiO2 growth using DEDEOS was studied by laser-induced thermal desorption (LITD) and TPD as a function of repetitive growth cycles composed of DEDEOS deposition at 300 K followed by thermal annealing to 820 K. The amount of SiO2 growth per cycle initially decreased as a function of cycle until reaching a constant value after approximately 10 cycles. Finally, DEDEOS deposition of SiO2 was studied in a high pressure chamber at surface temperatures between 873 K and 1003 K and at a pressure of 0.5 Torr. The deposition of SiO2 as a function of exposure was found to display a fast initial growth step followed by a slower step which continued indefinitely. The activation energy for SiO2 growth by DEDEOS in the slower growth step was found to be 49 ± 6 kcal/mol. This activation energy is very similar to the activation energy of 45 kcal/mol observed for SiO2 growth by tetraethoxysilane (TEOS).
Kinetics of Reactive Ion Etching of Polymers in an Oxygen Plasma: The Importance of Direct Reactive Ion Etching
Authors: Graham Sandra W. , SteinbrüChel Christoph 
Published: March 2011

AbstractThe etching of polymer films in oxygen-based plasmas has been studied between 5 and 100 mTorr in a reactive ion etch reactor using Langmuir probe and optical actinometry measurements. Results for the etch yield (the number of carbon atoms removed per incident ion) are analyzed in terms of a surface-chemical model for ion-enhanced etching proposed by Joubert et al. (J. Appl. Phys. 65, 5096 (1989)). A proper description of the results requires that this model be modified by including a term due to direct reactive ion etching and physical sputtering. The contribution by direct reactive ion etching to the overall etching turns out to be significant under all conditions and even dominant at the lowest pressures. The modified model should be applicable to the etching of polymers in other types of reactors, especially highplasma- density reactors. The relationship between these results and the anisotropic patterning of polymer films is also discussed.
Decomposition Study of Teos in Thermal Cvd
Authors: Takeuchi Hideki , Izumi Hirohiko , Kawasaki Atsushi 
Published: March 2011

AbstractThermal decomposition of tetraethoxysilane(TEOS) has been investigated in a vertical type LP-CVD reactor. The mass spectrum of reacting gas was found to have a feature corresponding to hexaethoxysiloxane ((H5C2O)3SiOSi(OC2H5)3). Trapped byproducts were found to include ethanol and ethoxy-based silica. Kinetic analysis of deposition rate profile indicated the existence of two intermediates. Feed gas residence time, as well as substrate temperature. directly affected the film quality.A vapor phase reaction model was proposed to explain these results. According to this model. TEOS decomposes into ethylene and triethoxysilanol. The latter reacts with TEOS to form hexaethoxysiloxane as observed by mass spectrometry. The triethoxysilanol, hexaethoxysiloxane and TEOS should be actual deposition precursors. Similar reaction continues to form ethoxybased siloxane polymers which are trapped from the exhaust gas.
The Role of Barium In the Heteroepitaxial Growth of Insulator and Semiconductors On Silicon
Authors: Chu T. K. , Santiago F. , Stumborg M. , Huber C. A. 
Published: March 2011

AbstractThe epitaxial growth of an insulator, BaF2, and semiconductors of the II-VI and the IV-VI families on Si substrates were carried out. In-situ XPS analyses during the growth of the first monolayers were used to study the surface chemical reactions involved. The results point to a common ingredient in these growths: that the Ba atoms are involved in forming interfacial compounds that would facilitate the heteroepitaxies. In the case of BaF2/Si, a BaSi2 compound has been identified previously. In the case of PbTe and CdTe, the heteroepitaxies on Si are made possible with the BaSi2 buffer. As a result, the impinging semiconductor molecules are broken up, and the metallic elements are ejected from the BaSi2 surface. A new surface chemical, BaTe, is thereby formed. These surface Ba compounds appear to be the dominant factors as the crystal orientations of the BaF2, CdTe, and PbTe layers are independent of those of the Si substrates.
Topographical Effects Regarding Trench Structures Covered with Rtcvd Sige Thin Films
Authors: Ritter G. , Schlote J. , Tillack B. 
Published: March 2011

AbstractThe paper presented discusses certain topographical effects being significant for the coverage of nonplanar structures with undoped and doped thin SiGe films. They are essential for new integrated heterojunction Si/SiGe devices. To investigate the coverage of topographical surfaces SiGe layers have been deposited on different trench structures in a Rapid Thermal Low Pressure single wafer CVD reactor (RTCVD) from the system SiH4, GeH4, and H2 using B2H6/ H2 and PH3/ H2 for the in-situ doping, respectively. Various deposition conditions and different film compositions have been used. The results especially the differences of the thickness distribution within trenches and on the surface have been discussed with regard to different CVD models taking into account distinguished reaction mechanisms.