bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Electrospun Dendrimer-Gelatin Hybrid Nanofiber Scaffold for Tissue Regeneration and Drug Delivery
Authors: Smith-Freshwater Alicia P , Bowlin Gary L , Yang Hu 
Published: April 2011

AbstractGelatin has been widely used to develop tissue engineering scaffolds because it has many attractive properties. Dendrimer provides a versatile, compositionally and structurally controlled architecture to construct nanomedicine. This study was aimed at developing a novel electrospun dendrimer-gelatin nanofiber scaffold to best mimic natural extracellular matrix (ECM) to promote tissue formation and serve as a reservoir for controlled drug delivery. Starburst™ polyamidoamine (PAMAM) dendrimer G3.5 was covalently bonded to the gelatin backbone and electrospun into nanofibers. Doxycycline (DC), which is an effective antibiotic that has the ability to inhibit matrix metalloproteinase, was encapsulated into the nanofiber scaffold. The electrospun DC-gelatin scaffold provides a bacterial free environment for cell growth and tissue regeneration. The resulting dendrimer-gelatin nanofiber scaffold achieved a unique structural configuration where covalently bound three-dimensional dendritic nanospheres were evenly distributed along the elongated dimension of the nanofiber, and both dendrimer and gelatin had numerous functional groups suitable for accommodating multiple functional entities and high payload of drugs. The development of this new scaffold with the capability of delivering multiple functional entities was an important step towards the use of bioactive nanofibers to facilitate tissue regeneration and controlled drug release.
Nanomonitors: Nanomaterial Based Devices Towards Clinical Immunoassays
Authors: Prasad Shalini , Bothara Manish , Reddy Ravikiran , Carruthers John , Barrett Thomas 
Published: April 2011

AbstractThe immobilization of biomolecules on a solid substrate and their localization in “small” regions are major requirements for a variety of biomedical diagnostic applications, where rapid and accurate identification of multiple biomolecules is essential. In this specific application we have fabricated nanomitors for identifying specific protein biomarkers based on the electrical detection of antibody-antigen binding events.The nanomonitor, lab-on-a-chip device technology is based on electrical detection of protein biomarkers. It is based on developing high density, low volume multi-well plate devices. The scientific core of this technology lies in integrating nanomaterial with micro fabricated chip platforms and exploiting the improve surface area to volume to improve the detection.The devices that have been developed utilize electrical detection mechanisms where capacitance and conductance changes due to protein binding are used as “signatures” for biomarker profiling. In comparison to optical methods, the electrical detection technique is non-invasive as well as a label free. The signal acquisition is simple and it uses the existing data acquisition and signal analysis methods
Culture of Insect Heart Muscle Tissue and Its Applicability to Bio-Actuators
Authors: Akiyama Yoshitake , Iwabuchi Kikuo , Furukawa Yuji , Morishima Keisume 
Published: April 2011

AbstractAn insect heart (dorsal vessel) is well suited as an environmentally robust bioactuator since insect tissue is generally robust over culture conditions compared with mammalian tissue. In this paper, the applicability of a caterpillar dorsal vessel to a bioactuator was assessed by fabricating a micropillar actuator driven by dorsal vessel tissue and evaluating the response to electrical pulse stimuli. The actuator worked autonomously for more than 90 days at 25 °C without any maintenance. The average frequency and displacement for 30 s on the 28th day of culturing were 0.83 Hz and 41 μm, respectively. Furthermore, as a regulation method for the dorsal vessel, electrical pulse stimuli were applied to the micropillar actuator. The contractile delay was about 50 ms. A twitch contraction was evoked by electrical pulse stimulus at 20 ms in duration and 10 volts in amplitude. A tetanic contraction was observed when stimuli over 10 Hz were applied.
Fabrication of Ring-shaped Bioactuator Powered by Cardiomyocytes
Authors: Horiguchi Hiroshi , Akiyama Yoshitake , Morishima Keisuke 
Published: April 2011

AbstractWe have proposed a novel use of pulsating living cells as a driving source for a micro bio-actuator. Cardiyomyocytes contract autonomously using chemical energy. But, contractile force of a single cardiomyocyte is not enough to actuate a micro robot or a mechanical system. So it is necessary to reconstruct cardiomyocytes to increase the ability to contract. We focused on the reconstruction of cardiomyocytes using a basement membrane protein mixture. In this paper, we fabricated a prototype cardiomyocyte gel structure. We confirmed that the ring-shaped cardiomyocyte gel structure condensed around the central cylinder within the PDMS mold and contracted synchronously and autonomously.
Zone-Specific Changes in Micromechanical, Biochemical, and Structural Properties in Articular Cartilage from a Rabbit Joint Flexion Model
Authors: Li Cheng , King Karen B. , Pruitt Lisa A. 
Published: April 2011

AbstractMetacarpophalangeal (MCP) joint proximal bone-cartilage specimens from the fourth digit were collected from repetitively flexed and non-flexed (control) paws of four New Zealand White rabbits. The specimens were cryo-fractured to reveal a sagittal cut containing the cartilage zones of different collagen microstructure. Nanoindentation, Fourier Transform infrared microspectroscopic imaging (FTIRMI), and histology were performed on a region of interest (ROI) ∼400 microns wide and through the thickness of the cartilage with two goals in mind: (1) to examine the effect of collagen network structure (random in the mid zone versus organized in the deep zone) on the biomechanical and biochemical properties of cartilage; and (2) to understand the changes in these properties due to physical forces. We found that zone microstructure significantly affected the measurement of the local relaxed modulus measured by nanoindentation. The deep zone had a higher modulus than the mid zone (Wilcoxon paired test, p<0.05). We also found that flexion significantly decreased the proteoglycan content in both the mid and deep zones (Wilcoxon paired test, p<0.05), suggesting indirect repetitive loading in the rabbit paw can be damaging to the joint via down regulating proteoglycan synthesis in the mid and deep zone cartilage. This is the first study to simultaneously report the local zone-specific mechanical and biochemical properties in the rabbit joint flexion model.
Characterisation of Cell Adhesion to Substrate Materials and the Resistance to Enzymatic and Mechanical Cell-Removal
Authors: Griffiths Helen Jane , Harvey John G , Dean James , Curran James A , Markaki Athina E , Clyne T William 
Published: April 2011

AbstractCell-implant adhesive strength is important for prostheses. In this paper, an investigation is described into the adhesion of bovine chondrocytes to Ti6Al4V-based substrates with different surface roughnesses and compositions. Cells were cultured for 2 or 5 days, to promote adhesion. The ease of cell removal was characterised, using both biochemical (trypsin) and mechanical (accelerated buoyancy and liquid flow) methods. Computational fluid dynamics (CFD) modelling has been used to estimate the shear forces applied to the cells by the liquid flow. A comparison is presented between the ease of cell detachment indicated using these methods, for the three surfaces investigated.
Three Dimensional Morphology and Compressive Behaviour of Sintered Biodegradable Composite Scaffolds
Authors: Ghassemieh Elaheh 
Published: April 2011

AbstractPorous poly-L-lactide acid (PLA) scaffolds are prepared using polymer sintering and porogen leaching method. Different weight fractions of the Hydroxyapatite (HA) are added to the PLA to control the acidity and degradation rate. The three dimensional morphology and surface porosity are tested using micro CT, optical microscopy and scanning electron microscopy (SEM). Results indicate that the surface porosity does not change by addition of HA. The micro Ct examinations show slight decrease in the pore size and increase in wall thickness accompanied with reduced anisotropy for the scaffolds containing HA. SEM micrographs show detectable interconnected pores for the scaffold with pure PLA. Addition of the HA results in agglomeration of the HA which blocks some of the pores. Compression tests of the scaffold identify three stages in the stress-strain curve. The addition of HA adversely affects the modulus of the scaffold at the first stage, but this was reversed for the second and third stages of the compression. The results of these tests are compared with the cellular material model. The manufactured scaffold have acceptable properties for a scaffold, however improvement to the mixing of the phases of PLA and HA is required to achieve better integrity of the composite scaffolds.
Microstructures in the Formation of Chemical Gardens
Authors: Sainz-Diaz C. Ignacio , Escribano Bruno , Cartwright Julyan 
Published: April 2011

AbstractChemical gardens are biomimetic structures in the form of plants formed by a combination of salts which precipitate by a combination of convection forced by osmosis, free convection and chemical reactions. Chemical gardens may be implicated in other phenomena of industrial interest which involve precipitation across a colloidal gel membrane which separates two different aqueous solutions, for example, in cement technology and metal corrosion process. However, the variation in chemical composition, morphology and mechanical properties of the different surfaces of these formations is not well known yet. Several salts in different concentrations and conditions have been explored under terrestrial gravity and microgravity. The chemical garden structures have been characterised by morphology analysis, scanning electron microscopy, chemical analysis and x-ray diffraction, correlating these data with the biomimetic growth and the physical-chemical nanoprocesses involved in it. This approach can also be useful for the analysis of biomaterials with interesting biomechanical properties.
The Hydrolysis and Oxidation Behavior of Lithium Borohydride and Magnesium Hydride Determined by Calorimetry
Authors: Brinkman Kyle , Gray Joshua R. , Hardy Bruce , Anton Donald L. 
Published: April 2011

AbstractLithium borohydride, magnesium hydride and the 2:1 “destabilized” ball milled mixtures (2LiBH4:MgHM2) underwent liquid phase hydrolysis, gas phase hydrolysis and air oxidation reactions monitored by isothermal calorimetry. The experimentally determined heats of reaction and resulting products were compared with those theoretically predicted using thermodynamic databases. Results showed a discrepancy between the predicted and observed hydrolysis and oxidation products due to both kinetic limitations and to the significant amorphous character of observed reaction products. Gas phase and liquid phase hydrolysis were the dominant reactions in 2LiBH4:MgH2 with approximately the same total energy release and reaction products; liquid phase hydrolysis displayed the maximum heat flow for likely environmental exposure with a peak energy release of 6 (mW/mg).
Hydrogen Storage Properties of a Combined Li3AlH6-LiBH4 System
Authors: Choi Young Joon , Lu Jun , Sohn Hong Yong , Fang Zak 
Published: April 2011

AbstractLithium based complex hydrides, including lithium aluminum hydrides and lithium borohydride (LiAlH4, Li3AlH6 and LiBH4), are among the most promising materials due to their high hydrogen contents. In the present work, we investigated the hydrogen storage properties of a new combined system of Li3AlH6-LiBH4. The samples were made with small amounts of catalyst under low energy milling conditions. Thermogravimetric analysis (TGA) of a Ti-doped Li3AlH6/2LiBH4 indicated that the degree of hydrogen release reached 7.3 wt. % by the time the sample reached 450iÆc under a heating rate of 2iÆC/min. This increased to 8.8 wt. % when the sample was held at 450iÆCfor additional 8 hours minutes under this condition. The dehydrogenation product was a mixture of LiH and AlB2. This product could be rehydrogenated up to 3.8 wt. % under 24.1 MPa hydrogen pressure and 450iÆC.
Surface Enhanced Raman Spectroscopy and Cyclic Voltammetry Studies of Ni-rich Oxide Nanowires as Electrode Materials
Authors: Nguyen Que Anh , Bhargava Yash V. , Thorne Shawn A. , Cohen-Hyams Tzipi , Devine Thomas M. 
Published: April 2011

AbstractA novel electrode material for Ni metal hydride batteries, composed of electrochemically synthesized, Ni-rich oxide nanowires, was investigated in this study. The nanowires, grown on Alloy 600 in a high-temperature, high-pressure aqueous electrolyte, are typically 25nm in diameter and 5-10um long. Cyclic voltammetry, with surface enhanced Raman spectroscopy (SERS) suggests that anodic polarization of the wires converts Ni2+ species to Ni3+, present as γ–-NiOOH, the chemical phase involved in the charge/discharge reaction in Ni-MH batteries. The reversibility of the reaction was confirmed via multiple polarization cycles and SEM imaging. In addition, the current density and polarization behavior of the nanowires in 0.01M KOH solution is compared to that of planar NiO and Alloy 600. Results suggest that the nanowires, due to their higher surface area, achieves at least 10 times the current density (for a given apparent area) of the non-nanowire samples.
Thermoelectric Properties of YbBiPt and YBiPt Thin Films
Authors: Guner Sadik , Budak Satilmis , Muntele Claudiu I , Ila Daryush 
Published: April 2011

AbstractMonolayer thin films of YbBiPt and YBiPt have been produced with 560 nm and 394 nm thick respectively in house and their thermoelectric properties were measured before and after MeV ion bombardment. The energy of the ions were selected such that the bombarding Si ions stop in the silicon substrate and deposit only electronic energy by ionization in the deposited thin film. The bombardment by 5.0 MeV Si ions at various fluences changed the homogeneity as well as reducing the internal stress in the films thus affecting the thermal, electrical and Seebeck coefficient of thin films. The stoichiometry of the thin films was determined using Rutherford Backscattering Spectrometry, the thickness has been measured using interferometry and the electrical conductivity was measured using Van der Pauw method. Thermal conductivity of the thin films was measured using an in-house built 3ω thermal conductivity measurement system. Using the measured Seebeck coefficient, thermal conductivity and electrical conductivity we calculated the figure of merit (ZT). We will report our findings of change in the measured figure of merit as a function of bombardment fluence.
Effects of Mg Content on Zn1-xMgxO:Al Transparent Conducting Films
Authors: Li Xiaonan , Ray Hannah , Perkins Craig L. , Noufi Rommel 
Published: April 2011

AbstractConductive zinc oxide (ZnO) films are used extensively as transparent electrodes in thin-film photovoltaic solar cells. Compared with the widely used indium tin oxide (ITO) and tin oxide (SnO2), ZnO has a smaller optical bandgap. ZnO is commonly used as a front contact for copper indium gallium diselenide (CIGS) solar cells, but it forms a small, unfavorable conduction-band offset with the CdS layer. The optical bandgap of ZnO could easily be engineering by alloying with MgO or CdO. In this work, we try to optimize the ZnO for CIGS solar cells. The optical and electrical properties of Zn1-xMgxO:Al films fabricated by co-sputtering were studied. Two targets: ZnO:Al and MgO, were used. The ratio of ZnO/MgO was varied continuously on the 6”x6” glass substrate, and the effects of composition on the properties of the Zn1-xMgxO:Al films were investigated. The carrier concentration and mobility of the Zn1-xMgxO:Al films decreased quickly with increasing Mg content. However, the optical properties of the Zn1-xMgxO:Al films do not vary linearly with Mg content, as reported by most papers. The observed optical bandgap of Zn1-xMgxO:Al films is actually first narrowed, then increased with the Mg content. The shift in optical bandgap from narrow to wide occurs at around a composition of x = 0.07. After the point of x = 0.07, the bandgap width star increase but film sheet resistance already too low. Our result therefore suggests that the alloyed Zn1-xMgxO:Al does not benefit the CIGS solar cell.
Light management issues in intermediate band solar cells
Authors: Martí Antonio , Antolín Elisa , Cánovas Enrique , Linares Pablo García , Luque Antonio 
Published: April 2011

AbstractThis paper discusses several topics related to light management that improve our understanding of the performance and potential of the intermediate band solar cell (IBSC). These topics are photon recycling, photon selectivity and light confinement. It is found that neglecting photon recycling leads to underestimate the limiting efficiency of the IBSC in 7 points (56.1 % vs 63.2 %). Light trapping allows to effectively absorbing photons whose energy is associated to the weakest of the optical transitions in the IBSC, allowing also for higher efficiencies with lower device thickness. The impact of photon selectivity on the cell performance is also discussed.
Up Conversion for Photovoltaics
Authors: Conibeer Gavin , Shalav Avi , Trupke Thorsten , Green Martin 
Published: April 2011

AbstractAn up-converter (UC) absorbs two or more low-energy photons and emits a single high-energy photon. A down-converter (DC) absorbs a single high-energy photon and emits two or more low energy photons. The current work extends previous limiting efficiency analysis to a combination of UC and DC; an up converter with two levels; and to compare analyses using real air mass data with that modelling the sun as a blackbody. Analysis has been carried out both with the band gap of the cell as an optimized parameter and at a fixed value of 1.1eV. All of UC, DC and two level UC are shown to improve efficiencies for both spectra. Combined UC/DC improves the efficiency further for the 1.1eV band gap but gives a lower efficiency for the optimised band gap. The explanation for this unexpected result is presented based on the small coupling losses that result from absorption/re-emission in the DC. The limiting efficiencies of such an approach are very similar to several other third generation concepts such as impurity PV, Intermediate Band solar cells or three level tandems. However in practice the UC (or DC) approach has the advantage that the optical properties of the UC are decoupled from the electrical properties of the PV cell, and hence each can be optimised independently. This means that it may be the simplest third generation approach to implement using existing PV cells, if a reasonable UC efficiency can be obtained. Nonetheless experimental work on realising UC is at an early stage. Some of the work on rare earth doped UC is reviewed together with the potential to improve the spectral sensitivity to below band gap radiation.
Light Trapping in μc-Si:H Thin-film Solar Cells by Back Surface Reflector with Grating Structure Fabricated by Self-ordering Process
Authors: Sai Hitoshi , Fujiwara Hiroyuki , Kondo Michio 
Published: April 2011

AbstractBack surface reflectors (BSRs) with grating structures have been developed to enhance light trapping in thin-film microcrystalline Si (μc-Si:H) solar cells. As a grating structure, a periodic honeycomb-like dimple pattern with periods of 100 ˜ 450 nm has been fabricated on Al substrates by a self-ordering process using anodic oxidation of Al. A clear diffraction effect by the grating structure has been confirmed on the patterned Al using angle-dependent reflection measurement. From quantum efficiency measurements, we found that the periodically patterned BSR can confine the incident light effectively, especially at longer wavelengths. Nevertheless, short circuit current densities obtained from the patterned BSRs are rather comparable to that obtained from the random textured substrate. For further improvement of the light-trapping effect by the grating structure, it is necessary to realize higher diffraction efficiencies while maintaining high total reflectivity on the BSR structure.
Nanoimprint Lithography of Light Trapping Structures in Sol-gel Coatings for Thin Film Silicon Solar Cells
Authors: Heijna Maurits , Loffler Jochen , Van Aken Bas , Soppe Wim , Borg Herman , Peeters Patrick 
Published: April 2011

AbstractFor thin-film silicon solar cells, light trapping schemes are of uppermost importance to harvest all available sunlight. Typically, superstrates with randomly textured TCO front layers are used to scatter the light diffusively in pin-cells on glass. Here, we investigate methods to texture opaque substrates with both random and periodic textures, for use in nip-cells on metal foil. We applied an electrically insulating SiOx-polymer coating on a stainless steel substrate, and textured this barrier layer by nanoimprint. On this barrier layer the back contact is deposited for further use in the solar cell stack. Replication of masters with various random and periodic sub-micron patterns was tested, and, using scanning electron microscopy, replicas were found to compare well with the originals. The embossing of the barrier layer does not diminish its electrically isolating properties, and thus adds extra functionality to this layer. Masters with U-grooves of various sub-micrometer widths have been used to investigate the optimal dimensions of regular patterns for light trapping in the silicon layers. Angular reflection distributions were measured to evaluate the light scattering properties of both periodic and random patterns. These periodic patterns, comprising diffraction gratings, show promising results in scattering the light to specific angles, enhancing the total internal reflection in the solar cell.
Highly Conductive In4Sn3O12 Films Prepared by Pulsed Laser Deposition
Authors: O'Neil David H , Kuznetsov Vladimir , Jacobs Robert , Jones Martin O , Edwards Peter P 
Published: April 2011

AbstractHighly conductive (> 103 Ω-1cm-1) and transparent (∼ 90%) In4Sn3O12 films have been deposited using pulsed laser deposition (PLD) on glass substrates held at a temperature of 500°C under varying pressures of oxygen (2.5 mTorr ≤ PO2 ≤ 15 mTorr). The crystallinity and the roughness of the films were found to increase with the pressure of oxygen used during deposition. Electron concentrations of the order of 5×1020 cm-3 and mobilities as high as 30 cm2V-1s-1 were derived from the measurement of Hall coefficients. Both the electronic transport and optical properties of the films were found to be strongly sensitive to the pressure of oxygen used during deposition.