Efficient Fabrication Process Research Articles

Interplay between Amphiphilic Stabilizers and Cholesterol in the Stabilization of Itraconazole Nanoparticles Prepared by Flash Nanoprecipitation.

While flash nanoprecipitation (FNP) has proven to be an extremely rapid and highly efficient nanoparticle fabrication process for hydrophobic drugs, physical instability associated with nonequilibrium molecular orientation of amphiphilic stabilizers (ASs) in nanoparticles remains a major snag in the general application of this nanotechnology, particularly for a drug with ACDLog P in the range of ∼2-9. This study was aimed at elucidating the costabilizing role of cholesterol (CLT) in the FNP of AS-stabilized nanoparticles of itraconazole (ITZ), a model drug with an ACDLog P of 4.35 ± 1.22 and log P of 5.66. The presence of CLT was shown to reduce the initial particle size and markedly improve the short-term storage stability of ITZ nanoparticles. The stability-enhancement by CLT can be linked to its higher miscibility or stronger interaction with the AS hydrophobic moiety than with ITZ (as reflected by the absolute differences of their solubility parameter values). Surface analyses employing X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) suggest that, through the coprecipitation of CLT with ITZ to form a mixed hydrophobic drug core, the CLT molecules that are exposed on the core surface serve to afford a stronger and more timely surface anchorage of the AS hydrophobic moieties, thereby facilitating the rearrangement of AS molecules toward the stable micelle-like structure. The present findings offer a mechanistic insight into the interplay between amphiphilic stabilizer and costabilizer in enhancing the physical stability of drug nanoparticles and may carry important implications for the development of more stable and efficacious nanoparticle therapeutics.

Development of efficient fabrication processes for highly functional silicon nitride ceramics: a review

Development of efficient fabrication processes for highly functional silicon nitride ceramics: a review

Nanocomposite polyester fabric based on graphene/titanium dioxide for conducting and UV protection functionality

An efficient process for fabrication of electroconductive, antistatic, ultraviolet rays protective polyester fabric using a graphene/titanium dioxide (graphene/TiO2) nanocomposite is prepared. Polyester fabric was treated with graphene oxide (GO) using a simple exhaust method. The GO-treated polyester fabric was then immersed in TiCl3 aqueous solution which acted as reducing agent to yield a fabric coated with graphene/TiO2 nanocomposite. The treated fabric was characterised by X-ray diffraction and Fourier transform infrared spectroscopy. Surface resistivity, volume resistivity, static charge decay time and ultraviolet protection factor of treated fabric were also assessed. The electrical conductivity of the graphene/TiO2 nanocomposite-coated fabrics was improved significantly by the presence of graphene on the surface of polyester fabrics. Nanocomposite fabric also showed excellent mechanical properties and hydrophobicity. It also exhibited protection from UV radiations as shown by higher UPF due to the presence of titanium on the fabric surface.

Low-cost scalable printing of carbon nanotube electrodes on elastomeric substrates: Towards the industrial production of EAP transducers

Dielectric elastomer transducers are promising devices for a growing field of applications. However, to be competitive with established electromechanical transducer technologies, low-cost and efficient fabrication process is needed. In particular, the electrode composition and deposition method seem to be the key elements in this context. In this paper, authors use gravure printing for the deposition of thin and compliant MWCNT electrodes on PDMS films. Gravure printing is a high through put deposition method which allows printing complex electrode patterns whit high resolution and, therefore, is well suited for large scale production of dielectric elastomer transducers. Special attention was given to the adaptation of the MWCNT-based ink to the specific requirements of the gravure printing process in order to achieve stable and high quality printing. Furthermore, the effect of oxygen plasma treatment of the silicone substrate on the electro-mechanical behavior of electrode was investigated. In this context a comprehensive characterization of the electrodes behavior under uniaxial and biaxial strain was carried out. Two mechanisms that explain specific aspects of electro-mechanical behavior of electrodes are proposed.

A synergistic strategy for stable lithium metal anodes using 3D fluorine-doped graphene shuttle-implanted porous carbon networks

It remains a challenging task to solve the imperative problems facing lithium metal anodes for next-generation rechargeable batteries. Herein, a synergistic strategy is developed to suppress lithium dendrite growth, facilitate solid electrolyte interphase stabilization, and consequently improve lithium metal anode performance, through using a self-supporting three-dimensional fluorine-doped graphene shuttle-implanted porous carbon network as the multifunctional host matrix for lithium. The methodology emphasizes structural and interfacial synergism in controlling the nucleation and growth of lithium deposits, which can enable lithium dendrite-free deposition and high-efficiency lithium plating/stripping. Such a structure and interface-engineered electrode matrix not only acts as a favorable lithium reservoir to enable the electrode-level stability, as a current density regulator to manage the initial nucleation and subsequent growth of lithium, but also as an interfacial modifier to stabilize solid electrolyte interphase layers. As a result, the developed anode exhibits excellent electrochemical performance, retaining an average Coulombic efficiency as high as 99% over 300 cycles. Combined with a simple and efficient fabrication process, the study presented here offers a viable option for fabricating dendrite-free lithium metal anodes for lithium metal battery systems and at the same time, sheds light on other high-performance metal battery construction.

A Highly Sensitive Flexible Pressure Sensor Based on Polystyrene@Graphene Core-Shell Nanoballs

Many novel building highly sensitive flexible pressure sensors have achieved high development in recent years, showing their potential applications in the field of electronic skin and wearable health monitors. In this work, we report a fabrication of flexible film-shaped resistive-type pressure sensor with high performance and versatile applications by sandwiching PS balls@rGO core-shell nanomaterials film layer between two thin flexible polydimethylsiloxane sheets. The preparation of materials and the fabrication process of the sensor devices is simple, efficient and economy. Our PS balls@rGO based pressure sensors are able to detect pressing forces as low as 3.1 Pa, and have a low energy consumption (~1 μW) at a low bias voltage of 1V, fast response time of 50 ms, high sensitivity (50.9 kPa-1) in 3.1 Pa ~ 20 kPa, and high stability during 20,000 loading–unloading cycles. In addition, our flexible sensor can detect pressing, blood pulse, swallowing, skin pulling and joint activities when attached on human bodies. By an efficient scalable fabrication process, large-area integrated pressure sensors array was manufactured, enabling patterning for mapping spatial pressure distribution to large-area monitoring of body pressure, pulses and human actions.

Layer-by-layer self-assembly of reduced graphene oxide on bamboo timber surface with improved decay resistance

Because bamboo is easily attacked by many fungi, and conventional preservatives have many disadvantages including environmental pollution and human health damage, bamboo products should be protected with environmentally friendly methods. Herein, a novel and efficient process for fabrication of antifungal bamboo timber by coating with graphene materials is presented. The crystal phase, morphology, microstructure and other physicochemical properties of the as-prepared samples were characterized by XRD, Raman, SEM, EDX, XPS and FTIR. XRD studies and Raman spectrum confirmed that graphene oxide was reduced to graphene aggregates in the one-step hydrothermal reduction process. SEM images proved that reduced graphene oxide (RGO) nanoplates were deposited on bamboo timber surface by layer-by-layer self-assembly. EDX proved the carbon element composition of RGO coating on the bamboo surface. XPS and FTIR indicated strong interaction of hydrogen bond between bamboo substrate and RGO coating. The anti-fungal activity of bamboo timber with RGO coating was improved significantly when bamboo was infected by Gloeophyllum trabeum and Panerochaete chrysosporium.

A novel MEMS S-springs vibrating ring gyroscope with atmosphere package

This study presents a new MEMS vibrating ring gyroscope (VRG), which is driven by electrostatic force and detected by capacitance. A novel ring resonator with eight S-shaped symmetrical supporting springs is developed based on the advantageous characteristics of a thin-shell vibrating gyroscope. The capacitance electrodes, including the drive electrodes, the sense electrodes and the mode control electrodes, are designed according to the vibration characteristics of the ring resonator and the shape of the supporting springs. In addition, the operational principle of these electrode capacitors and the electrostatic force of the drive electrodes are discussed in detail. The gyroscope with high aspect-ratio structures is manufactured through an efficient fabrication process. Finally, the performance characteristics of the fabricated VRG are tested, and the experimentally obtained the zero-bias instability is about 0.0167°/s and angle random walk (ARW) is about 0.1363°/s1/2 at room temperature. Experimental results show that the VRG has a simple structure and relatively better performance characteristics for low and medium angular velocity measurements.

Fabrication of new polypyrrole/silicon nitride hybrid materials for potential applications in electrochemical sensors: Synthesis and characterization

ABSTRACTIn this research, an efficient fabrication process of conducting polypyrrole (PPy)/silicon nitride (Si3N4) hybrid materials were developed in order to be employed as transducers in electrochemical sensors used in various environmental and biomedical applications. The fabrication process was assisted by oxidative polymerization of pyrrole (Py) monomer on the surface of Si/SiO2/Si3N4 substrate in presence of FeCl3 as oxidant. To improve the adhesion of PPy layer to Si3N4 surface, a pyrrole-silane (SPy) was chemically bonded through silanization process onto the Si3N4 surface before deposition of PPy layer. After Py polymerization, Si/SiO2/Si3N4-(SPy-PPy) substrate was formed. The influence of SPy concentration and temperature of silanization process on chemical composition and surface morphology of the prepared Si/SiO2/Si3N4-(SPy-PPy) substrates was studied by FTIR and SEM. In addition, the electrical properties of the prepared substrates were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that the best silanization reaction conditions to get Si/SiO2/Si3N4-(SPy-PPy) substrate with high PPy adhesion and good electrical conductivity were obtained by using SPy at low concentration (4.3 mM) at 90°C. These promising findings open the way for fabrication of new hybrid materials which can be used as transducers in miniaturized sensing devices for various environmental and biomedical applications.

P‐181: Highly Efficient OLED Panels Based on Coated Porous Polymer Film as the Light‐Extraction Layer

We present the simple and efficient fabrication process of porous poly imide films for the light extraction layer of OLEDs. With a single coating process and a conventional immersion precipitation method, 1.4 times higher values of power efficiency and external quantum efficiency were achieved than the reference device. Also, we demonstrate the angular distribution of emitted light can be controlled through the process condition.

New opportunities for custom-shape patterning using polarization control in confocal laser beam interference setup

Fabrication of photonic devices requires fast and reliable microstructuring approach. For example, efficient generation of fine 2D patterns in thin metal films is needed in plasmonic metamaterial devices. In this paper, the authors present an approach for the flexible generation of the periodic pattern using a laser beam interference patterning setup. So far, interference patterning was mostly limited to the periodic patterns of lines and dots. A variety of interference patterns can be significantly increased by controlling the polarization orientation of each interfering beam. The authors demonstrate the experimental setup for polarization control in the confocal six-beam interference configuration. Various periodic intensity patterns were generated and observed with a CCD camera using this setup. Additionally, the generated patterns were replicated in a thin metal film experimentally. Efficient and simple fabrication process and relatively high patterning flexibility suggest that interference patterning with polarization control may become an important tool in metamaterial fabrication.

Mechanical and microstructural behavior of friction stir welded similar and dissimilar sheets of AA2219 and AA7475 aluminium alloys

Friction stir welding process has been employed to join similar and dissimilar 2.5 mm thick sheets of AA2219-O and AA 7475-T761 aluminium alloys. AA2219 and AA7475 Al alloys are utilized in the components of space shuttles and aircraft, respectively that require efficient fabrication process. Friction stir welding is a clean welding process capable of joining difficult to weld aerospace aluminium alloys. Tensile properties, microstructure, micro-hardness, and fracture surfaces of the friction stir welded joints were analyzed. Grain refinement is observed at the stir zone due to dynamic recrystallization caused by severe plastic deformation. Lowest strength for dissimilar joint is observed primarily due to non homogeneous movement of base materials consequent to differences in mechanical and physical properties. Minimum hardness was found at TMAZ retreating side for all joints due to the thermal softening. Fractured surfaces of the similar joints showed more ductile fracture compared to dissimilar joint which resulted in lower elongation of the dissimilar joints.

Fabrication of Metallic Nanodot Arrays Using Nano-Chemical Stamping Technique with a Polymer Stamp

The aim of this study is to develop metallic nanodot arrays with controlled morphology and alignment. To produce gold nanodot arrays with high throughput, the authors propose a new efficient fabrication process based on the templated thermal dewetting method, using a nano-chemical stamping technique with a polymer mold. This process comprises four steps: sputter etching on a quartz glass substrate, patterning of micrometer size by printing with acetone on the substrate by stamping with a polymer film stamp, deposition of a thin Au film on the substrate, and self-organization of the metal nanodot arrays by thermal dewetting. A new method, using a cyclo-olefin polymer film mold for chemical patterning by nano-chemical stamping, was examined. Since the acetone stamped on the substrate reduces the surface energy and affects the contact angle of the gold nanodots, the gold nanodots are distributed along the stamped pattern. It is found that the pattern stamped with acetone on the substrate works as a template for the thermal dewetting process. The nano-chemical stamping technique is useful in controlling the size and distribution of the nanodots.

A simple fabrication process for SiNx/SiO2 waveguide based on sidewall oxidation of patterned silicon substrate

A novel and efficient fabrication process based on sidewall oxidation of patterned silicon substrate is proposed and experimentally demonstrated for SiN/SiO waveguides on silicon substrate. The fabrication time of a 5.5 m-thick lower SiO cladding formed by the proposed sidewall oxidation method is only 1/3 of that required by conventional flat surface oxidation process. Thermal annealing process is carried out to reduce the propagation loss of the waveguide due to material absorption in the SiN core and the SiO upper cladding formed by plasma enhanced chemical vapour deposition. Furthermore, it is confirmed that waveguides fabricated by sidewall oxidation exhibit similar propagation loss as those obtained with conventional surface oxidation process.

Ink-jet printing assisted fabrication of thin film composite membranes

Modern printing techniques may facilitate membrane fabrication methods for the creation of novel polymer compositions and coatings. The interfacial polymerization reaction between diamine and triacyl chloride monomers is a highly efficient method to achieve currently used RO and NF thin film composite membranes. Here we present our investigation of the interfacial polymerization process using an ink jet printer for the application of an amine monomer to an ultrafiltration (UF) support as part of the polymerization method. In this study, single and multiple coatings of m-phenylene diamine (m-PDA) were applied to the UF support, without a draining step, before application of trimesoyl chloride (TMC). The resulting polymer films were characterized using FTIR and correlated to the amount of m-PDA printed on the UF support. The amount of crosslinking in the polyamide thin film increased as more m-PDA was printed on the support as indicated by XPS oxygen/nitrogen ratios. Also, the hydrophilicity of the surfaces could be explained with respect to the amount of polyamide crosslinking. SEM images of the membrane surfaces showed the progressive morphological changes to the surface as more m-PDA was printed. Salt rejection increased and the flux decreased as the amount of printed m-PDA increased, and was explained by amount of polymer crosslinking, surface hydrophobicity, and polyamide layer thickness. Further development of ink-jet printing within the context of interfacial polymerization methods, or for other membrane coating applications may accelerate the discovery of novel membranes, and lead to deeper understanding of membrane processes. Printing as a coating method exhibits higher accuracy and controllability compared to dip coating methods, that require removal of excess liquid or droplets via difficult to control draining or other steps, and which may eventually result in an overall more efficient fabrication process.

(Invited) Growth of Ordered ZnO Nanorods Arrays Using Anodic Porous Alumina Templates

The fabrication of ordered semiconductor nanostructures has attracted increasing interest due to its applicability to various functional devices. Among them, the semiconductor nanorods array is one of typical nanostructures available for the functional optical devices including solar cells, and display devices due to its unique physical properties originated from the geometrical structures. Although various fabrication processes for the nanorod arrays have been reported, the efficient fabrication process of the ordered semiconductor nanorods array has not been established so far [1]. In the present report, the formation of the highly ordered semiconductor (ZnO) nanorods array based on anodic porous alumina templates will be presented. The anodic porous alumina, which is formed by anodization of Al in acidic electrolyte, is one of typical self-ordered material with highly ordered hole arrangement [2]. The advantage of this material is its high controllability of the geometrical structures based on the anodizing conditions. Especially, under the appropriate low voltage anodization condition, the highly ordered hole array structures with small hole interval and hole size can be obtained [3]. The hole interval and hole size in this highly ordered porous alumina were typically 25 nm and 10 nm, respectively. In the present work, ZnO nanorods arrays were fabricated through the hydrothermal reaction [4] using the anodic porous alumina as a template for the synthesis. Based on the present process, the highly ordered arrays of ZnO nanorods could be fabricated on the substrates. The geometrical structures of the ZnO nanorods arrays were controlled by changing the structures of the porous alumina templates. The obtained nanostructures will be applied to the fabrication of various kinds of energy conversion devices, which require the highly ordered nanostructures of semiconductors. 1. W. I. Park, D. H. Kim, S.-W. Jung, G.-C. Yi, Appl. Phys. Lett., 80, 4232 (2002). 2. H. Masuda and K. Fukuda, Science, 268, 1466 (1995). 3. H. Masuda, K. Takenaka, T. Ishii, K. Nishio, Jpn. J. Appl. Phys., 45, L1165 (2006). 4. T. Shinagawa, S. Watase, M. Izaki, Cryst. Growth Des., 11, 5533 (2011).

Manufacturing of Peptide Microarrays Based on Catalyst-Free Click Chemistry.

Immobilization of peptides to a solid surface is frequently an important first step before they can be probed with a variety of biological samples in a heterogeneous assay format for research and clinical diagnostic purposes. Peptides can be derivatized in many ways to subsequently covalently attach them to an activated solid surface such as epoxy-functionalized glass slides. Here, we describe a clean, efficient, and reproducible fabrication process based on catalyst-free click chemistry compatible with the construction of low- to high-density peptide microarrays.

Laser-assisted Machining of Zirconia Ceramics using a Diamond Bur

Yttria-stabilized tetragonal zirconia polycrystal is a promising material for dental restoratives. The dominant manufacturing method of the dental restoratives comprises three steps. (1) Pressing (2) machining (3) final sintering. The method has disadvantages such as low geometrical accuracy and long process time in the final sintering stage. Thus, the direct machining method of the fully sintered Y-TZP which is difficult to machine is desired to realize an accurate, efficient and inexpensive fabrication process of the dental restoratives. We applied the laser-assisted machining process to machine fully sintered Y-TZP blocks. The tool adopted was diamond burs. A series of grinding experiments were conducted to assess the effectiveness of the laser assistance. The results revealed that the grinding force was reduced and the tool damage was reduced in the assisted processes while microcracks were observed on the surface. The conditions for the crack initiation was discussed. The laser-assisted grinding of Y-TZP was revealed to be effective for an efficient and relatively rough grinding process.

Influence of Composition and Chemical Arrangement on the Kinetic Stability of 147-Atom Au–Ag Bimetallic Nanoclusters

High calcination temperatures are often required in nanoparticle synthesis and an understanding of how heating affects the structure and chemical arrangement of bimetallic nanoclusters is essential to design efficient fabrication processes. We have investigated the kinetic stability of 147-atom Au–Ag nanoalloys with varying composition and chemical ordering using ensemble molecular dynamics simulations to replicate these high temperature conditions. Ag-rich mixed alloys undergo a diffusion-less “martensitic” structural transition from cuboctahedral to icosahedral; the melting temperature (Tm) of the subsequent icosahedra is dependent on the Au:Ag stoichiometry. Core@shell chemical arrangements do not behave in a similar manner: Tm strongly depends on the shell component; additionally Au55@Ag92 exhibits increased stability as a result of its icosahedral Au core. We also report a novel dependence of nanocluster phase transitions on the chemical arrangement, as shown by low temperature nonmartensitic atomic ...

Tactical grade MEMS vibrating ring gyroscope with high shock reliability

This study presents a microelectromechanical systems (MEMS) vibrating ring gyroscope (VRG), which can survive high shocks and then maintains the level of performance required for tactical navigation. The mechanical structure was designed using a combination of mathematical analysis and the finite element method. The high-aspect-ratio structures were then manufactured through an efficient fabrication process using a silicon-on-aluminum patterned glass (SOPG) wafer. To demonstrate the high shock resistance of the fabricated VRG, a shock of 15,000g was applied by a gas-gun, and its performance parameters were measured. The VRG, which has an operating frequency of 17kHz, demonstrated performance satisfying the tactical grade requirements, i.e., bias instability, scale factor accuracy, and angular random walk less than 1°/h, 50ppm, and 0.1°/h1/2, respectively. The test results show that the proposed VRG can be used effectively in tactical navigation systems, especially when both performance and high shock reliability are crucial, such as in guided munitions.