Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Fabrication

  • bottom-up fabrication
  • controlled fabrication
  • device fabrication
  • direct fabrication
  • facile fabrication
  • rapid fabrication

  • Terms modified by Fabrication

  • fabrication condition
  • fabrication cost
  • fabrication method
  • fabrication methods
  • fabrication procedure
  • fabrication process
  • fabrication route
  • fabrication step
  • fabrication technique
  • fabrication techniques
  • fabrication technology

  • Selected Abstracts

    Drifters and the Dancing Mad: The Public School Music Curriculum and the Fabrication of Boundaries for Participation

    CURRICULUM INQUIRY, Issue 3 2008
    ABSTRACT Recent reforms in the general music curriculum have, for the most part, failed to lessen the attrition rates of African Americans from public school music programs. In this article I assert that an embodied ideal of cultural nobility, exemplified by Auguste Rodin's famous statue, The Thinker, has unconsciously operated as a template for participation. As a model comportment in the Western musical tradition, The Thinker has a broader relevance insofar as other school subjects emerged from similar cultural ideals. Beginning with the early period of public music instruction up to the present, I examine the construction of racial boundaries by linking a specific body comportment hailed as worthy by the music curriculum to historically constructed notions of Whiteness. This issue has been underexplored in research in both music and general education. For that reason, this article examines overlapping systems of reasoning about music, comportment, class, religion, language, nationality, and race in professional and popular texts from the early 1800s to the present. This positions public music instruction as authored, not by pedagogical insight alone, but through changes in musical taste, social practices, strategies of governing populations, and definitions of worthy citizenship. There are three levels of analysis. The first is a personal account of the early manifestations of attrition of African Americans from school music programs. The second level of analysis brings the problem of equity into proximity with the tradition of genteel comportment that permeated the training of the good ear or listener and the fabrication of the bona fide citizen. These, I argue are congruent with the historical construction of Whiteness as a standard mark of worthiness. At the third level of analysis, I take up present-day curriculum designs. This section discusses how the language of the music curriculum continues to draw boundaries for participation through protocols that regulate musical response. Here, I argue that the exclusion of popular genres such as hip-hop should be rethought in light of the evidence that shifting historical definitions for music fabricated an overly restrictive template for comportment, recognizing the prototype of Whiteness as the sole embodiment of merit. [source]

    Fabrication of a Sensitive Cholesterol Biosensor Based on Cobalt-oxide Nanostructures Electrodeposited onto Glassy Carbon Electrode

    ELECTROANALYSIS, Issue 24 2009
    Abdollah Salimi
    Abstract Electrodeposited cobalt oxide (CoOx) nanomaterials are not only used for immobilization of cholesterol oxidase (ChOx) but also as electron transfer mediator for oxidation of H2O2 generated in the enzymatic reaction. Voltammetry and flow injection analysis (FIA) were used for determination of cholesterol. FIA determination of cholesterol with biosensors yielded a calibration curve with the following characteristics: linear range up to 50,,M, sensitivity of 43.5,nA ,M,1 cm,2 and detection limit of 4.2,,M. The apparent Michaelis-Menten constant and the response time of the biosensor are 0.49,mM and 15,s, respectively. This biosensor also exhibits good stability, reproducibility and long life time. [source]

    Fabrication of Nanoporous Copper Film for Electrochemical Detection of Glucose

    ELECTROANALYSIS, Issue 21 2009
    Sirilak Sattayasamitsathit
    Abstract A nanoporous copper film was fabricated on a copper wire by electrodeposition of copper/zinc alloy and chemically etching of zinc. The surface morphology was investigated by SEM. When applied to detect glucose in an amperometric flow injection system the porous copper electrode provided 12 times higher sensitivity than solid copper. It could be continuously used up to 50 times (%RSD=5.7). Different preparations of the porous film provided reproducible responses (P<0.05). Detection of glucose in E. coli cultivation medium compared well with spectrophotometric technique (P<0.05). This simple technique can produce a nanoporous electrode with good performances and can easily be applied to other metals and analytes. [source]

    Fabrication, Characterization, and Application of ,Sandwich-Type' Electrode Based on Single-Walled Carbon Nanotubes and Room Temperature Ionic Liquid

    ELECTROANALYSIS, Issue 17 2008
    Xuzhi Zhang
    Abstract The much-enhanced electrochemical responses of potassium ferricyanide and methylene blue (MB) were firstly explored at the glassy carbon electrode modified with single-walled carbon nanotubes (SWNT/GCE), indicating the distinct electrochemical activity of SWNTs towards electroactive molecules. A hydrophobic room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), was used as electrode modification material, which presented wide electrochemical windows, proton permeation and selective extraction ability. In consideration with the advantages of SWNTs and RTIL in detecting target molecules (TMs), a novel strategy of ,sandwich,type' electrode was established with TMs confined by RTIL between the SWNT/GCE and the RTIL membrane. The strategy was used for electrochemical detection of ascorbic acid (AA) and dopamine (DA), and detection limits of 400 and 80 fmol could be obtained, respectively. The selective detection of DA in the presence of high amount of AA could also be realized. This protocol presented many attractive advantages towards voltammetric detection of TMs, such as low sample demand, low cost, high sensitivity, and good stability. [source]

    Fabrication and Application of a Novel Modified Electrode Based on Multiwalled Nanotubes/Cerium(III) 12-Tungstophosphoric Acid Nanocomposite

    ELECTROANALYSIS, Issue 11 2008
    Bin Fang
    Abstract A novel multiwalled nanotubes (MWNTs)/Cerium(III) 12 - tungstophosphoric acid (CePW) nanocomposite film glassy carbon electrode was prepared in this paper. Electrochemical behaviors of the CePW/MWNTs modified electrode were investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). This modified electrode brought new capabilities for electrochemical devices by combining the advantages of carbon nanotubes, rare-earth, and heteropoly-acids. The results demonstrated that the CePW/MWNTs modified electrode exhibited enhanced electrocatalytic behavior and good stability for the detection of guanine and adenine in 0.1,M PBS (pH,7.0). The experimental parameters were optimized and a direct electrochemical method for the simultaneous determination of guanine and adenine was proposed. The detection limit (S/N=3) for guanine and adenine was 2.010,8,M and 3.010,8,M, respectively. Further, the acid-denatured calf thymus DNA was also detected and the result was satisfied. [source]

    Fabrication of Active Horseradish Peroxidase Micropatterns with a High Resolution by Scanning Electrochemical Microscopy

    ELECTROANALYSIS, Issue 16 2007
    Xuemei Li
    Abstract We used a new reactive species OH, to fabricate active horseradish peroxidase (HRP) micropatterns with a high resolution by scanning electrochemical microscopy (SECM) coupled with a carbon fiber disk electrode as the SECM tip. In this method, except for active HRP micropatterns predesigned other regions on a HRP-immobilized substrate were deactivated by OH, generated at the tip held at ,1.7,V in 1.0,mol/L KCl containing 2.010,3 mol/L benzoquinone (BQ) (pH,8.0). The feedback mode of SECM with a tip potential of ,0.2,V was used to characterize the active HRP micropatterns in 1.0,mol/L KCl containing 2.010,3 mol/L BQ and 2.010,3 mol/L H2O2. [source]

    Carbon Ceramic Electrodes Modified with Laccase from Trametes hirsuta: Fabrication, Characterization and Their Use for Phenolic Compounds Detection

    ELECTROANALYSIS, Issue 9 2007
    Behzad Haghighi
    Abstract Fungal laccase (Lc) from the basidiomycete Trametes hirsuta was immobilized on top of a carbon ceramic electrode using physical absorption. Direct, unmediated heterogeneous electron transfer between Lc and the carbon ceramic electrode (CCE) under aerobic conditions was shown. The bioelectrocatalytic reduction of oxygen on Lc-CCE started at about 430,mV vs. Ag|AgCl|KClsat at pH,3.5 and moved with about 57,mV in the cathodic region per pH unit. The Lc-modified CCE was then used as a biosensing detection element in a single line flow injection system for the amperometric determination of a variety of phenolic substrates of the enzyme. The experimental conditions were studied and optimized for catechol serving as a model compound. Statistical aspects were applied and the sensor characteristics and Michaelis-Menten constants of the investigated phenolic compounds were calculated and compared with those obtained for solid graphite electrodes modified with Trametes hirsuta laccase. The results showed that the CCE based biosensor in comparison with the solid graphite based biosensor offers a lower detection limit, a wider linear dynamic range, and excellent operational stability with no sensor passivation, indicating that the sol,gel lattice improves the electrochemical behavior of the biosensor. [source]

    Fabrication and Properties of Conducting Polypyrrole/SWNT-PABS Composite Films and Nanotubes

    ELECTROANALYSIS, Issue 11 2006

    Abstract We report the electropolymerization and characterization of polypyrrole films doped with poly(m-aminobenzene sulfonic acid (PABS) functionalized single-walled nanotubes (SWNT) (PPy/SWNT-PABS). The negatively charged water-soluble SWNT-PABS served as anionic dopant during the electropolymerization to synthesize PPy/SWNT-PABS composite films. The synthetic, morphological and electrical properties of PPy/SWNT-PABS films and chloride doped polypyrrole (PPy/Cl) films were compared. Characterization was performed by cyclic voltammetry, atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy. SEM and AFM images revealed that the incorporation of SWNT-PABS significantly altered the morphology of the PPy. Cyclic voltammetry showed improved electrochemical properties of PPy/SWNT-PABS films as compared to PPy/Cl films. Raman Spectroscopy confirmed the presence of SWNT-PABS within composite films. Field effect transistor (FET) and electrical characterization studies show that the incorporation of the SWNT-PABS increased the electronic performance of PPy/SWNT-PABS films when compared to PPy/Cl films. Finally, we fabricated PPy/SWNT-PABS nanotubes which may lead to potential applications to sensors and other electronic devices. [source]

    Comparison of Different Strategies on DNA Chip Fabrication and DNA-Sensing: Optical and Electrochemical Approaches

    ELECTROANALYSIS, Issue 22 2005
    Sabine Szunerits
    Abstract New strategies for the construction of DNA chips and the detection of DNA hybridization will be discussed in this review. The focus will be on the use of polypyrrole as a linker between a substrate and oligonucleotide probes. The modification step is based on the electrochemical copolymerization of pyrrole and oligonucleotides bearing a pyrrole group on its 5, end. This strategy was employed for the immobilization of oligonucleotides on millimeter-sized electrodes, microelectrode arrays, as well as for the local structuring of homogeneous gold surfaces. Our approaches for the localized patterning of gold surfaces will be also discussed. Localized immobilization was achieved by using an electrospotting technique, where a micropipette served as an electrochemical cell where spot sizes with 800,,m diameters were fabricated. The use of a microcell using a Teflon covered metal needle with a cavity of 100,,m resulted in immobilized probe spots of 300,,m. Scanning electrochemical microscopy (SECM) was also used, and surface modifications of 100,,m were obtained depending on the experimental conditions. Different detection methods were employed for the reading of the hybridization event: fluorescence imaging, surface plasmon resonance imaging (SPRI), photocurrent measurements, and voltamperometric measurements using intercalators. Their advantages concerning the various immobilization strategies will also be discussed. [source]

    Fabrication and Characterization of DNA/QPVP-Os Redox-Active Multilayer Film

    ELECTROANALYSIS, Issue 23 2004
    Jianyun Liu
    Abstract Calf thymus DNA was immobilized on functionalized glassy carbon, gold and quartz substrates, respectively, by the layer-by-layer (LBL) assembly method with a polycation QPVP-Os, a quaternized poly(4-vinylpyridine) partially complexed with osmium bis(2,2,-bipyridine) as counterions. UV-visible absorption and surface plasmon resonance spectroscopy (SPR) showed that the resulting film was uniform with the average thickness 3.4,nm for one bilayer. Cyclic voltammetry (CV) showed that the total surface coverage of the polycations increases as each QPVP-Os/DNA bilayer added to the electrode surface, but the surface formal potential of Os-centered redox reaction shifts negatively, which is mainly attributed to the intercalation of redox-active complex to DNA chain. The electron transfer kinetics of electroactive QPVP-Os in the multilayer film was investigated by electrochemical impedance experiment for the first time. The permeability of Fe(CN) in the solution into the multilayer film depends on the number of bilayers in the film. It is worth noting that when the multilayer film is up to 4 bilayers, the CV curves of the multilayer films display the typical characteristic of a microelectrode array. The nanoporous structure of the multilayer film was further confirmed by the surface morphology analysis using atomic force microscopy (AFM). [source]

    Microdimensional Polyaniline: Fabrication and Characterization of Dynamics of Charge Propagation at Microdisk Electrodes

    ELECTROANALYSIS, Issue 17 2004
    Karolina Caban
    Abstract We describe fabrication of microdimensional polyanilne films in a controlled manner by voltammetric potential cycling or controlled potential electrolysis on platinum microdisk electrodes. The film grows in a form of hemispherical microdeposits, and its size largely exceeds the size of a Pt microdisk. Consequently, the film covers both the Pt substrate as well as the surrounding glass seal. Since the adhering polyaniline layer is conducting, the latter situation may lead to an increase in the effective electrode surface area. The lateral growth of polyaniline films outside the microdisk has also been demonstrated by performing diagnostic voltammetric experiments with use of a double microdisk set-up in which independent polarization of each disk is feasible. Microelectrode-based chronocoulometry, that involves an uncomplicated well-defined reduction potential step starting from the emeraldine (conducting) form and ending at leucoemeraldine (nonconducting) form, yields (upon application of a sufficiently short pulse) a well-defined linear response of charge versus square root of time that is consistent with the linear effective diffusion as the predominant charge propagation mechanism. When describing the system kinetics in terms of the effective (apparent) diffusion coefficient, we expect this parameter to be on the level of 10,8,cm2 s,1 or lower. The relative changes in dynamics of charge transport are discussed with respect to the polyaniline film loading, the size of microdisk electrode, expansion of the active electrode area, and the choice of electrolyte (strong acid) anion. The results are consistent with the view that when Pt microelectrode is modified with PANI deposit exceeding the size of the microdisk substrate, it behaves in a way as if its surface area is effectively much larger than the geometric area of Pt microdisk. [source]

    Using the Aggregation of Latex Polymers in the Fabrication of Reproducible Enzyme Electrodes

    ELECTROANALYSIS, Issue 17 2003
    Wibowo Rahmat
    Abstract An enzyme electrode for glucose is described as a model system to demonstrate a fabrication method using latex aggregation and entrapment of enzyme. Electrosterically-stabilized latex particles synthesized by emulsion polymerization in batch from acrylic acid, methyl methacrylate and butyl acrylate, and glucose oxidase were coagulated together at pH,5.5 with ethanol. A platinum disk electrode dipped in the solution becomes coated with latex/enzyme. The relative thickness of the film and relative amount of enzyme may be controlled by the time the electrode is in contact with the solution. The enzyme was then immobilized by covalent attachment of amine groups to carboxylic moieties in the polymer using 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide hydrochloride and N -hydroxysuccinimide. Five minutes contact with the latex/enzyme solution and subsequent amide coupling, gave electrodes with a reproducibility of 5.7% RSD, a wide dynamic range (0,100,mM) and good storage properties. [source]

    Fabrication and evaluation of complementary logic circuits using zinc oxide and pentacene thin film transistor

    Hiroyuki Iechi
    Abstract We fabricated hybrid complementary inverters with n-channel zinc oxide (ZnO) transistors as the n-type inorganic material and p-channel organic transistors using pentacene as the p-type organic material. The complementary inverter exhibited a large voltage gain of 10 to 12 and a cutoff frequency of 0.5 kHz. ZnO thin film transistors show n-type semiconducting properties having field-effect mobility of 2.110,3 cm2/Vs. On the other hand, pentacene thin film transistors show p-type semiconducting properties having field-effect mobility of 3.210,2 cm2/Vs. We describe basic charge transfer characteristics of ZnO thin films. The results obtained here demonstrate that it is important for the transistor using ZnO to be injected charge from electrode to semiconducting material effectively. 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(9): 36,42, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10085 [source]

    Fabrication of enclosed SU-8 tips for electrospray ionization-mass spectrometry

    ELECTROPHORESIS, Issue 24 2005
    Santeri Tuomikoski Dr.
    Abstract We describe a novel electrospray tip design for MS which is fabricated completely out of SU-8 photoepoxy. A three-layer SU-8 fabrication process provides fully enclosed channels and tips. The tip shape and alignment of all SU-8 layers is done lithographically and is therefore very accurate. Fabrication process enables easy integration of additional fluidic functions on the same chip. Separation channels can be made with exactly the same process. Fluidic inlets are made in SU-8 during the fabrication process and no drilling or other postprocessing is needed. Channels have been fabricated and tested in the size range of 10,,m10,,m,50,,m200,,m. Mass spectrometric performance of the tips has been demonstrated with both pressure-driven flow and EOF. SU-8 microtips have been shown to produce stable electrospray with EOF in a timescale of tens of minutes. With pressure driven flow stable spray is maintained for hours. Taylor cone was shown to be small in volume and well defined even with the largest channel cross section. The spray was also shown to be well directed with our tip design. [source]

    A General Process for the Fabrication of Air-Stable Metallic Particles (Cd, Zn and Al) by the Decomposition of Alkyl,Metal Compounds

    Aharon Gedanken
    Abstract The thermolysis of alkyl,metal compounds under autogenic pressure, with the three metals Cd, Zn, and Al as examples, suggest that this might become a general method for preparing a composite where the metal is the core and carbon the shell. The air-stability of these composites is also demonstrated. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

    Low Temperature Fabrication of ,-TCP,PCL Nanocomposites for Bone Implants,

    Michael Bernstein
    Abstract A method to fabricate strong bioresorbable calcium phosphate,polymer nanocomposites with low polymer content without exposing the material to excessively high-processing temperatures is reported. Dense ,-TCP-based nanocomposites containing 5 or 15,vol% of uniformly distributed polycaprolactone (PCL) polymer were obtained by mixing ,-TCP nanopowder with PCL dissolved in chloroform followed by room temperature consolidation at the high pressure of 2.5,GPa (cold sintering). The composites had an attractive combination of compressive strength and ductility, and their dissolution behavior was similar to that of pure cold sintered ,-TCP. The immersion of ,-TCP,PCL composites in simulated body fluid (SBF) yielded in vitro deposition of a bone-like apatite layer suggesting the ability of these materials to bind to native bone tissue upon implantation. [source]

    Fabrication of Load-Bearing NiTi Scaffolds for Bone Ingrowth by Ni Foam Conversion,

    Irena Gotman
    Highly porous NiTi scaffolds for bone ingrowth were fabricated by reactive conversion (PIRAC) of commercially available Ni foams. These open cell ,trabecular NiTi' scaffolds possess high strength and ductility and exhibit low Ni ion release. PIRAC deposition of a thin titanium nitride (TiN) layer further improves the corrosion characteristics of "trabecular NiTi" and allows for material bioactivation by alkali treatment or biomimetic Ca phosphate deposition. [source]

    Fabrication and Microstructure of C/Cu Composites,

    Yiwen Liu
    C/Cu composites were prepared by a melting infiltration technique in vacuum. In order to improve the wettability between Cu and carbon fibers, Ti (8,wt.-%) and Cr (1,wt.-%) were added to the Cu alloy. Microstructures of the composites and interface between C and Cu were investigated by XRD, SEM, EDS and HRTEM. The results show that the Ti and Cr improved the wettability between Cu and CC preform and the infiltration ability of Cu into CC preform greatly. The prepared C/Cu composites are characterized as having good interface bonding and high density. In the process of infiltration, Ti and Cr concentrate on the boundary of carbon fiber. Formation of TiC results from the reaction of Ti and C between Cu and carbon fiber. [source]

    Process Cost Comparison for Conventional and Near-Net-Shape Cermet Fabrication,

    Yuhong Xiong
    Tungsten carbide,cobalt (WC,Co) is a widely used cermet that is generally fabricated into bulk parts via conventional powder metallurgy (P/M) methods. Because this material (and other cermets) is very hard and wear resistant, diamond grinding is generally required to fabricate complex parts. As an alternative, studies have shown the Laser Engineering Net Shaping (LENS) process to be a technically feasible method, allowing for fabrication of near-net-shape parts. The economic trade-offs, however, have not been previously characterized. In this work, technical cost modeling (TCM) is applied to compare the costs of fabricating WC,Co parts with the P/M process to those of the LENS process. Cost drivers are identified and sensitivity analysis is conducted. Results reveal that the uncertainty in functional unit has a significant effect on relative process costs, and the cost is sensitive to order size only if less than ten parts are produced. It is concluded that the LENS process is economically preferable if part size is small or part shape is complex. The P/M process is more suitable to produce large parts in simple shapes. [source]

    Powder Metallurgical Near-Net-Shape Fabrication of Porous NiTi Shape Memory Alloys for Use as Long-Term Implants by the Combination of the Metal Injection Molding Process with the Space-Holder Technique,

    Manuel Khl
    Abstract A new method was developed for producing highly porous NiTi for use as an implant material. The combination of the space-holder technique with the metal injection molding process allows a net-shape fabrication of geometrically complex samples and the possibility of mass production for porous NiTi. Further, the porosity can be easily adjusted with respect to pore size, pore shape, and total porosity. The influence of the surface properties of powder metallurgical NiTi on the biocompatibility was first examined using human mesenchymal stem cells (hMSCs). It was found that pre-alloyed NiTi powders with an average particle size smaller than 45,,m led to the surface properties most suitable for the adhesion and proliferation of hMSCs. For the production of highly porous NiTi, different space-holder materials were investigated regarding low C- and O-impurity contents and the reproducibility of the process. NaCl was the most promising space-holder material compared to PMMA and saccharose and was used in subsequent studies. In these studies, the influence of the total porosity on the mechanical properties of NiTi is investigated in detail. As a result, bone-like mechanical properties were achieved by the choice of Ni-rich NiTi powder and a space-holder content of 50,vol% with a particle size fraction of 355,500,,m. Pseudoelasticity of up to 6% was achieved in compression tests at 37,C as well as a bone-like loading stiffness of 6.5,GPa, a sufficient plateau stress ,25 of 261,MPa and a value for ,50 of 415,MPa. The first biological tests of the porous NiTi samples produced by this method showed promising results regarding proliferation and ingrowth of mesenchymal stem cells, also in the pores of the implant material. [source]

    Fabrication and Evaluation of Chitin-Based Nerve Guidance Conduits Used to Promote Peripheral Nerve Regeneration,

    Yumin Yang
    Chitin product was prepared from the chitosan counterpart and both were found to be equally biocompatible with cultured Schwann cells. Chitin- and chitosan-based nerve guidance conduits (NGCs) were surgically implanted to bridge 10-mm-long neural defects in rat sciatic nerves. The regenerative outcome provided positive evidence that chitin- and chitosan-based NGCs produce the similar beneficial effects on peripheral nerve regeneration. [source]

    Mass Fabrication of Small Cell Spheroids by Using Micro-patterned Tissue Culture Plate,

    Akinari Iwasaki
    A newly designed micro-patterned chamber was utilized to fabricate cell spheroids with a constant size (<200,,m) and cell number. By applying cytochalasin D as a chemical to control cell adhesion and aggregation, thousands of aggregated cells were formed in each patterned chamber. Importantly, the formed cell spheroids were collected by a simple pipetting process without using proteinase. [source]

    Fabrication of Fe,Cr,Al Oxide Dispersion Strengthened PM2000 Alloy Using Selective Laser Melting,

    John C. Walker
    Rapid prototyping using the selective laser melting process has been successfully used in the manufacture of solid walls from melt sensitive mechanically alloyed PM2000 FeCrAl ODS powder. Despite melting of the powder, the technique allowed the retention of the nanoscale oxide dispersion due to the high cooling rates. Results showed that coarsening and agglomeration of ODS particles was more dependent on laser scan speed than the maximum laser power. [source]

    Fabrication of Periodic Microstructures in Pentaerythritol Triacrylate Through Femtosecond Laser Interference Two-Photon Polymerization,

    Andrs Lasagni
    Fabrication of periodic, two-dimensional microstructures in pentaerythritol triacrylate (PETIA) is demonstrated through femtosecond laser interference patterning. Planar arrayed structures of different periodicities and geometries were fabricated using three, four, and five interfering beams from an 800,nm ultrafast femtosecond laser. The periodic topography can be varied from isolated conical pillars to interconnected cellular structures by simple control of the interference pattern in combination with energy dose. [source]

    Fabrication of Galactosylated Polyethylenimine and Plasmid DNA Multilayers on poly (D,L -lactic acid) Films for in situ Targeted Gene Transfection,

    Yan Hu
    This study presents surface-mediated targeted in situ gene delivery from gene-tagged poly(D,L -lactic acid) (PDLLA) films, which were fabricated via a layer-by-layer (LbL) assembly technique with galactosylated polyethylenimine (GP) and plasmid DNA (pDNA, pSV-,-galactosidase). A linear growth of GP/pDNA multilayered films was observed. The pDNA was continuously released from multilayered films for over 32,h. The multilayered structure degraded and simultaneously formed GP/pDNA complexes in situ when exposing to a physiological environment. The pDNA was well protected by GP against DNase I digestion within formed GP/pDNA complexes. Our results demonstrated that GP contributes to receptor-mediated targeting for cell uptake and in situ gene transfection. The results reported here are potentially important for gene therapy, surface engineering of biomaterials, tissue engineering and implant technology. [source]

    A Soft Molding Process for Fabrication of Micromachine Parts from Stainless Steel Powder,

    Mohamed Imbaby
    This work introduces a valid approach to fabricate high quality micromachine parts from stainless steel powder using soft molding and powder metallurgy techniques. In soft molding, SU-8 and negative replicas micromolds are produced. A mixture of Duramax B-10007 and B-1000 is successfully used as a binder in the preparation of stainless steel slurry. Sintering in forming gas atmosphere is very effective of preventing the oxidation of the stainless. [source]

    Fabrication of Al2O3/SiC Composite Microcomponents using Non-aqueous Suspension,

    Hany Hassanin
    This paper introduces a new process for fabrication of high resolution Al2O3/SiC composite microcomponents using softlithography and non-aqueous ceramic suspension. Polysilazane is used to provide both binding force and SiC composition. The shape retention and dimensions of the microcomponents were analyzed using a scanning electron microscope. Surface roughness, shrinkage, and density of the resultant sintered components were also discussed. [source]

    Hot-Pressed Glass Matrix Composites Containing Pyrochlore Phase Particles for Nuclear Waste Encapsulation,

    A.R. Boccaccini
    As alternative immobilization materials for Pu-bearing nuclear waste, lead-containing glass matrix composites with homogeneously distributed lanthanum zirconate pyrochlore particles (up to 30,% by volume) have been developed. Fabrication by hot pressing at the relatively mild temperature of 610,C leaves the pyrochlore structure of the La zirconate unchanged, which is crucial for the containment of radioactive nuclei. The Figure, an SEM image of a polished sample with 30,% La2Zr2O7, demonstrates the homogeneous particle distribution and absence of pores. [source]

    Inkjet-Printed Single-Droplet Organic Transistors Based on Semiconductor Nanowires Embedded in Insulating Polymers

    Jung Ah Lim
    Fabrication of organic field-effect transistors (OFETs) using a high-throughput printing process has garnered tremendous interest for realizing low-cost and large-area flexible electronic devices. Printing of organic semiconductors for active layer of transistor is one of the most critical steps for achieving this goal. The charge carrier transport behavior in this layer, dictated by the crystalline microstructure and molecular orientations of the organic semiconductor, determines the transistor performance. Here, it is demonstrated that an inkjet-printed single-droplet of a semiconducting/insulating polymer blend holds substantial promise as a means for implementing direct-write fabrication of organic transistors. Control of the solubility of the semiconducting component in a blend solution can yield an inkjet-printed single-droplet blend film characterized by a semiconductor nanowire network embedded in an insulating polymer matrix. The inkjet-printed blend films having this unique structure provide effective pathways for charge carrier transport through semiconductor nanowires, as well as significantly improve the on-off current ratio and the environmental stability of the printed transistors. [source]

    Fabrication and Characterization of Superhydrophobic Surfaces with Dynamic Stability

    Xi Yao
    Abstract Superhydrophobic surfaces of dynamic stability are crucial for applications in water-repellent materials. In this work, a hierarchical structure composed of a dendritic microporous surface with nanostructured porosity is demonstrated that shows robust superhydrophobicity with dynamic stability. The hierarchical structures are obtained on both copper foils and wires by a dynamic gas-bubble template-assisted electrochemical deposition method. The substrates can then be modified with alkyl thiols to obtain the surface superhydrophobicity. A new kind of testing, mechanical monitor-assisted continuous water surface strokes, is developed to reveal the dynamic stability of the as-prepared superhydrophobic copper wires. The as-prepared superhydrophobic copper wires can exert a high propulsive force, and particularly, show little adhesive force in the process of continuous strokes on the water surface, exhibiting robust superhydrophobicity with dynamic stability. The approach allows a strategy for the fabrication of superhydrophobic surfaces with dynamic stability, and suggests a new method to evaluate the dynamic stability of superhydrophobic surfaces. [source]