bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Quartz Crystal Microbalance Cell Biosensor: Detecting Nocodazole Dependent Microtubule Disruption Dynamics In Living Cells
Authors: Marx Kenneth A. , Zhou Tiean , Montrone Anne , Braunhut Susan J. 
Published: April 2011

ABSTRACTA Quartz Crystal Microbalance (QCM) was used to create a biosensor utilizing living adherent endothelial cells (ECs) as the biological sensing element. This EC QCM biosensor detected the effect of varying concentrations of nocodazole, a microtubule binding and disrupting drug, on the adherent cells as they altered the underlying QCM device state frequency, Δf, and motional Resistance, ΔR, shift values. Over the dose range 0.11-15 μM nocodazole, the Δf shift values decreased significantly in magnitude in a dose dependent fashion over a 5-6 hr incubation period following drug addition to a limiting value, with a 900 nM midpoint. This effect is consistent with nocodazole's known dose dependent effect on the disruption of microtubules. At all drug concentrations, the relative Δf decrease with time was found to be very similar and well fit by a single exponential decay equation. For all nocodazole doses, t 0.5 was invariant, averaging t 0.5 = 0.83 ± 0.14 hr. These data demonstrate that a single dynamic sensing system within the cell, the microtubules, responds to the addition of nocodazole and its response can be quantified by the biosensor. These results indicate that the EC QCM biosensor can be used to detect EC cytoskeletal alterations and dynamics and may be a valuable screening method for all classes of biologically active drugs or biological macromolecules that affect cytoskeleton perturbations or cellular attachment.
Characterisation of Biomedical Materials, Cells & Interfaces using Environmental SEM (ESEM)
Authors: Stokes D.J. , Rea S.M. , Porter A. E. , Best S. M. , Bonfield W. 
Published: April 2011

ABSTRACTThe ability of Environmental Scanning Electron Microscopy (ESEM) to image insulating and/or moist specimens without the need for the removal of volatile components or the application of a conductive coating has significantly increased the potential range of experiments and observations that can be performed at the high resolution of electron microscopy. Such a technological advance has particularly important implications for the study of soft matter, complex fluids and biological specimens [1]. Thus an important field of research to which ESEM can be applied is the study of materials for biomedical applications such as tissue engineering. The bioactivity of these materials is dependent upon such factors as phase composition, chemical composition, surface activity, crystallinity and microstructure. Using ESEM it is possible to obtain surface-sensitive, specimen-dependent secondary electron images (in the absence of specimen coating), yielding potentially new perspectives on microstructure to complement information derived from other techniques. We have used ESEM to study the apposition of bone on hydroxyapatite-based biomedical materials, from both in vitro and in vivo investigations.
Optical Characterization of Biological and Other Systems
Authors: Bezrukova Alexandra G. 
Published: April 2011

ABSTRACTMultiparametric optical analysis (MOA) can provide further progress in characterization and on-line control of biological and other disperse systems with nanoparticles as the disperse phase in various dispersive media. MOA includes the nondestructive simultaneous testing of disperse systems by different compatible optical methods such as refractometry, absorption, fluorescence, light scattering (integral and differential, static and dynamic, unpolarized and polarized). For the solution of inverse optical problems various techniques can be applied. By optical methods it is possible to determine parameters of disperse system's state (mean equivalent diameter and number of particles, mean refractive index and mass of disperse phase, number and mass distributions) and parameters of particle's structure. This paper is devoted to characterization of biological particles that can be approximated as bilayered spheres (blood-substitutes, liposomes, etc.) and to polarization measurements of disperse systems (viruses, bacterial cells, etc.) which can help to develop on-line control of environment.
Characterization of Chemically and Topographically Modified Siloxane Elastomer for Controlled Cell Growth
Authors: Gibson Amy L. , Wilson Leslie H. , Wilkerson Wade R. , Feinberg Adam W. , Seegert Charles A. , Baney Ronald H. , Brennan Anthony B. 
Published: April 2011

ABSTRACTA main limitation of biomedical devices is the inability to start, stop, and control cell growth making it crucial to develop biomaterial surfaces that induce a desired cellular response. Micropatterns of ridges and pillars were created in a siloxane elastomer (Dow Corning) by casting against epoxy replicates of a micromachined silicon wafer. Silicone oils were incorporated to determine the change in modulus and surface energy caused by these additives. SEM and white light interference profilometry verified that the micropatterning process produced high fidelity, low defect micropatterns. Mechanical analysis indicated that varying the viscosity, weight percent and functionality of the added silicone oil could change the elastic modulus by over an order of magnitude (0.1-2.3 MPa). As a self-wetting resin, silicone oils migrate to the surface, hence changing the surface properties from the bulk. Both topographical and chemical features define the surface energy, which in combination with elastic modulus, dictate biological activity. The results imply that the morphology, mechanical properties and surface energy of the siloxane elastomer can be modified to elicit a specific cell response as a function of engineered topographical and chemical functionalization.
Polymeric Tissue Culture Substrates patterned by UV Irradiation
Authors: Welle Alexander , Gottwald Eric , Weibezahn Karl-Friedrich , Dertinger Herman 
Published: April 2011

ABSTRACTWe studied the physico/chemical effects of deep UV irradiation of polystyrene, PMMA and polycarbonate with respect to cell adhesion and protein immobilization. Photochemical modifications of the polymer surfaces yielded unstable peroxides and carboxylic acid groups. Patterned protein adsorbates were realized by coupling via carbodiimid activation of the COOH moieties. We have immobilized enzymes and antibodies. It was observed that hepatoma cells (HepG2) and fibroblasts (L929) adhered in the presence of serum proteins in the culture medium on the irradiated regions of the substrate without any further treatment.
Controlled Growth Factor Delivery By Mechanical Stimulation
Authors: Lee Kuen Yong , Peters Martin C. , Anderson Kenneth W. , Mooney David J. 
Published: April 2011

ABSTRACTGrowth factor delivery using polymer matrices is one exciting approach to replace or regenerate tissues. Most growth factor delivery systems, however, have been designed to operate under static conditions, regardless of dynamic environments in the body. Considering the dynamic environment of our body (e.g., bone, muscle, and blood vessel), mechanical stimulation is an important signal that could be readily exploited. We hypothesize that polymer matrices, which release growth factors in response to mechanical stimulation, could provide a novel approach to engineer tissues in mechanically stressed environments. We report here a model system, comprised of alginate hydrogel and vascular endothelial growth factor (VEGF), which upregulates the release of the growth factor in response to mechanical stimulation and subsequently promotes granulation tissue formation in animals. This approach may find a number of potential applications in tissue engineering, as well as in drug delivery.
An In Vitro Study of Nano-fiber Polymers for Guided Vascular Regeneration
Authors: Miller Derick C. , Thapa Anil , Haberstroh Karen M. , Webster Thomas J. 
Published: April 2011

ABSTRACTBiomaterials that successfully integrate into surrounding tissue should match not only the tissue's mechanical properties, but also the dimensions of the associated nano-structured extra-cellular matrix (ECM) components. The goal of this research was to use these ideals to develop a synthetic, nano-structured, polymeric biomaterial that has cytocompatible and mechanical behaviors similar to that of natural vascular tissue. In a novel manner, poly-lactic acid/polyglycolic acid (PLGA) (50/50 wt.% mix) and polyurethane were separately synthesized to possess a range of fiber dimensions in the micron and nanometer regime. Preliminary results indicated that decreasing fiber diameter on both PLGA and PU enhanced arterial smooth muscle cell adhesion; specifically, arterial smooth muscle cell adhesion increased 23% when PLGA fiber dimensions decreased from 500 to 50 nm and increased 76% on nano-structured, compared to conventional structured, polyurethane. However, nano-structured PLGA decreased endothelial cell adhesion by 52%, whereas adhesion of these same cells was increased by 50% on polyurethane. For these reasons, the present in vitro study provides the first evidence that polymer fiber dimensions can be used to selectively control cell functions for vascular prosthesis.
Enhanced Cytocompatibility Properties of Hydroxyapatite Doped with Trivalent Ions
Authors: Massa Elizabeth A. , Slamovich Elliott B. , Webster Thomas J. 
Published: April 2011

ABSTRACTHydroxyapatite (HA) is a bone-like ceramic used as a coating for dental and orthopedic implants. It is well known for its good cytocompatibility properties, but is limited in use due to its high solubility within the body and mechanical properties that differ from surrounding tissue and bone. The present in vitro study investigated a variety of dopants as a way to further enhance the good cytocompatibility properties of HA as well as address these problematic properties. The dopants investigated were divalent (magnesium and zinc) and trivalent (yttrium, lanthanum, indium, and bismuth) ions. Of the trivalent ions, yttrium and indium have smaller ionic radii than calcium. The present study showed osteoblast adhesion to be statistically greater (p < 0.1) on yttrium-doped HA and indium-doped HA than on undoped HA. Since yttrium and indium are both trivalent ions of a smaller ionic radius than calcium, and other ions of different size and charge did not show significant changes in osteoblast adhesion, these results suggest that substituting divalent calcium with a trivalent ion of smaller size encourages osteoblast adhesion.
Complex Material Using β-Cyclodextrins and Nickel-Zinc Ferrite to Obtain a Magnetically Targetable Drug Carrier
Authors: Bocanegra Alberto , Mohallem Nelcy D. S. , Sinisterra Rubén D. 
Published: April 2011

ABSTRACTIn this study we describe the preparation and the characterization of a complex material using β-cyclodextrin covalently bound to Ni-Zn ferrite to obtain a magnetically targetable drug carrier. The physical-chemical characterization was performed through Fourier transformed infrared spectroscopy, X-ray diffraction, XRD, thermal analysis (TG/DTA), and atomic absorption spectroscopy. The results pointed out that β-cyclodextrin is externally covalently bound to Ni-Zn ferrite. However it was also verified that the β-cyclodextrin cavity is free and can include bioactive agents. The most interesting feature of this approach is the combination of magnetic properties and the host:guest technology to obtain an efficient targetable drug carrier system.
Polypeptide Ultrathin Films by Vacuum Deposition: Preparation and Characterization
Authors: Fulghum Timothy M. , Yamagami Hiroyuki , Tanaka Kuniaki , Usui Hiroaki , Shigehara Kiyotaka , Advincula Rigoberto C. 
Published: April 2011

ABSTRACTPolypeptide ultrathin films covalently grafted on solid substrates have attracted considerable attention in the interfacial polymer science community over the past couple of years. The potential applications of these films ranges from applications in liquid crystal displays, biosensors, optical devices, etc.. Their study may address important biocompatibility issues. We have synthesized polypeptide ultrathin films through the use of the physical vapor deposition technique. We expect to gain better insight into the polymerization process of the NCA monomers, as well as, possible control of the secondary structure.Through use of the vapor deposition technique and the amino acid n-carboxy anhydride (NCA) benzyl serine we have been able to prepare polymeric amino acids for analysis. Benzyl serine NCA was evaporated in high vacuum at a temperature of 95-130°C. Different substrates have been used to examine the effects of chemical binding sites on polymerization and secondary structure formation. From IR-spectroscopy and optical microscopy it was evident that without a free amine initiator on the surface of the substrate, polymerization would not occur. Analysis of the films with IR and optical microscopy were used to determine optimum deposition and polymerization conditions. The methyl peak around 3000 cm-1, amide peak at 1650 cm-1 and the carbonyl stretching at 1750 cm-1 evidence of the monomer are greatly reduced or disappear in the deposition range of 40-100nm/min.Analysis of the films with attenuated total reflectance (ATR) Infrared spectroscopy was used to examine the secondary structure. Values of amide 1 peak at 1632 cm-1, representing the carbonyl stretching, and the peak at 1530 cm-1, representing the carbon nitrogen stretching, match with literature values of beta sheet conformation.
The Technological Analysis of RMS Titanic's Coal: The Enhancement of Archaeological Research
Authors: Sheehan Michael S. , Sickels-Taves Lauren B. 
Published: April 2011

ABSTRACTThis research focuses on coal recovered from the debris field created when R.M.S. Titanic sank on 15 April 1912. The primary objectives are to evaluate the variety of different sources of coal represented in the Titanic sample, and to identify the specific location of these sources. The methods used to evaluate the research objectives include a variety of trace element, petrographic, and palynological analyses. The results of this study provide critical insight into the socioeconomic circumstances that contributed to the enormity of the disaster.
Technological investigation of luster decorated ancient majolicas
Authors: Padeletti G. , Fermo P. , Gilardoni S. 
Published: April 2011

ABSTRACTIn this work some luster decorated ancient ceramics have been analyzed in order to acquire knowledge about technological procedures in luster production during the Renaissance period in Italy. Luster is a thin decorative metallic film present on the surfaces of some previously glazed ancient majolicas. It was obtained by applying on the majolica surface a mixture containing silver and copper compounds. Subsequently the object was fired in a reducing atmosphere.It was found that the luster color, red-like or gold-like, depends not only on the chemical composition, determined by Inductively Coupled Plasma Emission Spectroscopy (ICP-OES), but on the dimensions of silver and copper metallic nanoparticles forming the luster too. Nanocrystals' dimensions and structural characteristics were determined by Transmission Electron Microscopy (TEM).As obtaining a satisfactory luster depends on the composition of the underlying glaze too, the chemical composition of the glazes have been determined and the analytical data were submitted to statistical multivariate analysis.
The Early History of Glassmaking in the Venetian Lagoon: A Microchemical Investigation
Authors: Mass Jennifer L. , Hunt John A. 
Published: April 2011

ABSTRACTThe compositions of well-dated archaeological glasses from the Northern Adriatic have been determined to learn more about the origins of the Renaissance Venetian glassmaking industry. Electron probe microanalysis (EPMA) was used to characterize thirty-seven late antiquity (5th – 7th centuries) glass finds from Torcello, an island located five miles to the northwest of the Rialtine islands that make up modern Venice. The late antiquity glass data was used in conjunction with two groups of medieval glass data, a predominately 6th –10th centuries Torcello group analyzed by Brill and an 8th-14th centuries Venetian lagoon group analyzed by Verità to gain insight into the technological evolution of glassmaking in the lagoon. The three data sets were then examined within the context of archaeological evidence for a medieval glass furnace complex at Torcello. Our data on the late antiquity glasses reveals that a decline in Roman-style glassmaking technology during this period may have contributed to Venice's late medieval and Renaissance glassmaking innovations.
Analysis of Electromigration Extrusion Failure Mode in Damascene Copper Interconnects
Authors: Arnaud Lucile , Tartavel Gérard , Berger Thierry , Mondon François , Truche Robert 
Published: April 2011

ABSTRACTThe electromigration performance of copper damascene interconnects has been studied with respect to hillock formation and is compared to void formation failure mode. The metal lines consisted of Chemical Vapor Deposition (CVD) copper deposited on CVD TiN and capped with SiN. SiO2 was used for copper lines insulation and final passivation. Two line widths (0.5 and 3µm) have been characterized. It is shown that higher activation energy values are obtained for void formation failure mode, respectively Ea = 0.86 eV for wide lines (poly-grain microstructure) and Ea =1.04 eV for narrow lines (quasi-bamboo microstructure) than for extrusion failure mode. Failure analysis performed with a Scanning Electron Microscope (SEM) showed that grain boundaries are active diffusion paths in polycrystalline copper lines whereas interface diffusion is believed to be the main diffusion path in narrow lines. Extrusions are shown to occur at the upper interface of copper damascene lines and to extend laterally as a consequence of cracks in dielectric layers and are thus responsible for short circuit between adjacent lines. Implications on extrapolated lifetimes at operating conditions are discussed.
The Effect of Initial Void Configuration on the Morphological Evolution Under the Action of Normalized Electron Wind Forces
Authors: Oren Ersin Emre , Ogurtani Tarik Omer 
Published: April 2011

ABSTRACTIn these studies a comprehensive picture of void shape evolution dynamics and its strong dependence on the initial configuration has been thoroughly investigated by utilizing hypocycloid algebra to generate four different shapes of main interest. Our mathematical model on the isotropic diffusion and mass accumulation on void surfaces, under the action of applied electrostatic potential and capillary effects, follows a novel irreversible but discrete thermodynamic formalism of interphases and surfaces.As a result during the intragranual motion, in addition to the crescent-like slit formation, very rich and also unusual void morphological variations such as fragmentations into the daughter voids or inner island generation have been observed under the severe (normalized) electron wind intensities or very long exposure times. In these numerical experiments, the Euler's method of finite differences with an automatic time step self-adjustment has been utilized in combination with a rather powerful and fast indirect boundary element method (IBEM) for the solution of the Laplace equation.
Comparative Study on Wafer-Level and Package-Level Electromigration Reliability for Sub-Quarter Micron Logic Devices
Authors: Park Young B. , Lee Duk W. 
Published: April 2011

ABSTRACTThe effects of Al underlayer between Ti and TiN on the electromigration (EM) lifetime of Al stack film were compared by the package-level and conventional wafer-level EM tests. The higher EM resistance of the Al stacks prepared with Ti underlayer can be best explained by their better Al (111) texture and grain size distribution than those with TiN underlayer. The surface roughness of the underlayer is related to the grain size distribution and surface roughness of Al film.
The Electronic Structure and other Properties of Amorphous Silicon Nitride Investigated with Density Functional Theory
Authors: Kroll Peter 
Published: April 2011

AbstractStructural models of amorphous silcon nitride, a-Si3N4. consisting of 112-448 atoms were studied using density functional methods. We used continuous random alterating networks with well-defined topology for the respersentation of chemical order in the material as theoretical precursors. The models were optimized within the DFT framework and compared them to one “ab inito derived” model obtained from quenching a hypothetical melt. The strong chemical order is maintained in the network models even after Car-Parrinello molecular dynamic (CPMD) simulations at elevated temperatures for several pico-seconds, In contrast, the “ab initio derived” model exhibits n-N bonds.The optimized strutures of Si3N4 have between 2.6 and 3.2 g/vm3 and comprise few topological defects only. The dominant defects are ever over-coordinated Si and N atoms and the 2-connected is averaged over a dozen modles is, averaged over a dozen models, about 1%. Some models are even free of three-connected Si. The calculated bulk moduli decrease with decreasing density of the a-Si3N4 model. We furthermore investigated the properties of the material ater alloying elements such as H and O, espically their capacity to reduces interal strain.
Effect of Pulsed Magnetic Fields on Crystallization of Polymers
Authors: Levin Mark N. 
Published: April 2011

ABSTRACTThe effect of pre-crystallization pulsed magnetic field (PMF) treatment of linear flexible-chain polymers on kinetics of their crystallization and structure in the crystalline state has been studied in polydimethylsiloxane (PDMS) and polyethylene oxide (PEO). It was established that the PMF treatment can destruct the initial net of non-chemically bonded “physical nodes” of the polymer and thus turn the melt into a metastable state with the increased sensitivity to regimes of crystallization. The effect revealed can lay the foundation for the development of new effective methods of controlled crystallization of the flexible-chain polymers, including fractionation and crystallization of polymorphic polymers in the chosen structural modification.
Molecular Modeling of Defect Structures in Pentacene
Authors: Miska Paul K. , Drummy Lawrence F. , Martin David C. 
Published: April 2011

ABSTRACTWe have studied defect structures in the crystalline organic molecular semiconductor pentacene. Our investigations included the calculation of free surface energies on low index planes. It was found that that the (001) surface had the lowest energy ∼50 mJ/m2, roughly half that of the other low index planes, (100) and (010) ∼120 mJ/m2 and ∼140 mJ/m2 respectively. These calculations were then compared to experimental data from vapor grown crystals using optical microscopy, Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM). We also modeled dislocations dipoles of varying Burgers vector and dipole length. It was found that dislocations were accommodated by extensive molecular deformation near the defect core, as well as a well defined stacking fault that occurred down the length of the dipole. Finally, we investigated low angle tilt grain boundaries. It was seen that low angle boundaries relaxed through molecular deformation in the first layer of molecules at the boundary as well as bending of the (001) planes.