Use In Many Applications Research Articles

Large-Angle, Broadband, and Multifunctional Directive Waveguide Scatterer Gratings

Conventional surface-relief gratings are inefficient at deflecting normally incident light by large angles. This limits the overall efficiency of grating-based optical instruments and also restricts their use in many applications. Here, we demonstrate a simple approach for the design of diffraction gratings that can be highly efficient for large deflection angles, while also offering additional functionality. Such gratings are composed of a unit cell comprising a vertically oriented asymmetric slot waveguide. The unit cell shows oscillating unidirectional scattering behavior that can be precisely tuned as a function of the waveguide length. This occurs due to interference between multiple modes excited in the structure by the incident light. In contrast to metasurface-based gratings with multiple resonant subelements, a periodic arrangement of such nonresonant diffracting elements allows for broadband operation and a strong tolerance for variations in angle of incidence. Full-wave simulations show that our grating designs can exhibit diffraction efficiencies ranging from 94% for a deflection angle of 47° to 80% for a deflection angle of 80°. To show the multifunctionality of our approach, we also demonstrate a flat polarization beamsplitter and a polarization insensitive grating.

3D Printing of Powder‐Based Inks into Functional Hierarchical Porous TiO2 Materials

Integrating multifunctional semiconducting metal oxide powders into a 3D printing technique to construct hierarchical porous structures is highly desirable and remains a significant challenge. Herein, an extrusion‐based 3D printing strategy is developed that can assemble TiO2 powders into hierarchical porous structures with multiscale pores at both the macro‐ and microscale. Powder‐based TiO2 inks with a significant shear‐thinning behavior and adequate storage modulus and yield stress are developed to meet the requirements of 3D printing of TiO2 in an air environment without the need for an additional solidification treatment, which provides good printing flexibility. The hierarchical porous structures with a relatively high compressive strength provide the 3D‐printed TiO2 structures with great potential for use in many applications, including filtration, thermal insulation, biomedical scaffolds, catalyst supports, and energy conversion. Compared with scaffolds with a compact morphology, the hierarchical porous TiO2 scaffold as a photoelectrode achieves a higher nitrogen photofixation yield due to its high surface adsorption and activation capacity caused by its porous morphology. Importantly, the powder‐based ink design and extrusion‐based 3D printing approach are readily extended to other semiconducting metal oxides such as ZnO and their composites.

Speed Control of BLDC Motor using Open Loop, PID Controller and Neural Network

The low cost of manufacturing having higher performance is main goal of upcoming and present applications. However, its possible to achive these aims using brushless DC motors (BLDC), due to its use in many applications. The applications such as sppining, drilling, elevators, lathes, etc can be exicuted using BLDC motor and can replace conventional DC brush motor. The effective vechiel control required for applications of variable speed can be achived using BLDC motors. This paper presents speed control of BLDC motor for open loop using PID and neural network techniques and their comparative study. From the simulation study it is observed that neural network gives better performance compaiered to other technique.

Improving impact, tensile and thermal properties of thermoset unsaturated polyester via mixing with thermoset vinyl ester and methyl methacrylate

The brittleness of thermoset unsaturated polyester (UP) limits its usefulness in many applications. Use of appropriate additives may improve the toughness of this material. The aim of this present study is to characterize the mechanical and thermal properties of the toughened UP and to relate these properties to the fracture surface morphology of the UP before and after adding various loadings of thermoset vinyl ester (VE) with 10% methyl methacrylate (MMA). VE loadings chosen were 10, 20, 30, and 40 wt%. UP mixed with 30%VE and 10%MMA displayed the best performance with a maximum impact strength of 314 kJ/m2, a 17.6% increase compared to that of neat UP. This sample also had the highest tensile strength of 64 MPa (an increase of 45.5%), higher elongation at the break of 13% (an increase of 27%), and higher thermal resistance. Addition of 30% VE and 10% MMA significantly improves a range of important properties of UP. This blend has a high potential to be used in UP resin applications where toughness is required.

3D Printed Injection Molding for Prototyping Batch Fabrication of Macroscale Graphene/Paraffin Spheres for Thermal Energy Management

Paraffin is a phase change material that can store thermal energy, and it has been used in a variety of applications. However, the low thermal conductivity of paraffin hinders the further expansion of its use in many applications. Thus, it is of great interest to identify and develop composites that can improve the thermal conductivity of paraffin to maximize its heat capacity. Here, we report a facile fabrication method for producing spherical paraffin/graphene composites with thermal conductivities enhanced by 57%. We used fused deposition 3D printing to build a prototype mold in which spherical paraffin/graphene composites were successfully fabricated.

Fluorine doping of nanostructured TiO2 using microwave irradiation and polyvinylidene fluoride

Fluorine doped metal oxides have shown great promise for use in many applications including Li-ion batteries (LiBs), photocatalysis and dye-sensitized solar cells. Both F-TiO2 and TiOF2 have been studied extensively for this purpose. However, fabrication of fluorine doped titanium oxide requires the use of dangerous fluorinated chemicals such as trifluoroacetic acid, hydrofluoric acid and fluorine gas which are both difficult to handle and create significant waste detrimental for the environment. Additionally, current procedures for fabrication of F-TiO2 and TiOF2 require long heating times which are inefficient, wasting large amounts of energy. Because of these factors, fabrication of F-TiO2, TiOF2 and of other important fluorine doped metal oxides is expensive and dangerous to make. In this work, two new methods were used to greatly improve the safety and efficiency of synthesis. First, the fluorinated waste was eliminated by using the safe and inert polymer, polyvinylidene fluoride (PVDF), as the fluorine source. Second, microwave (MW) irradiation was used to reduce the time and energy required for synthesis by addition of the MW absorber, graphene, into the precursor material. The results show that when using the PVDF fluorine source with conventional oven heating it results in low levels of F-TiO2 which are dependent on heating temperatures. However, when using microwave irradiation high levels of doping were achieved creating both F-TiO2 and TiOF2 in as little as 6 min compared to several hours. This work has shown that by combining both PVDF and microwave irradiation fabrication of F-TiO2 and TiOF2 can now be done safely and efficiently with greatly reduced environmental impact.

The Impact of Selectively Plasticized Poly (ethylene oxide) (PEO) Block in Nanostructured Polystyrene−PEO−Polystyrene Triblock Copolymer Electrolytes

All polymer electrolytes, including block polymer (BP) electrolytes exhibit low ionic conductivity compared to liquid electrolytes. For homopolymer electrolytes, the ionic conductivity can be increased by incorporating plasticizer into the polymer network. However, the subsequent weakened mechanical structure of the network precludes its use in many practical applications. In this work, we selectively plasticize the PEO block in a polystyrene PS-PEO-PS triblock copolymer electrolyte using a PEO-like plasticizer: tetraethylene glycol dimethyl ether (TEGDME). Unlike its homopolymer (PEO) electrolyte counterpart, the mechanical properties of the PS-PEO-PS triblock copolymer electrolyte are not drastically degraded by this plasticizer because it is immiscible in the nonpolar PS block domains. Polymer electrolyte membranes were cast from lithium trifluoromethanesulfonate (LiTFS) solutions with the corresponding polymers. The molar ratio of ethylene oxide to Li+ is 16 for all electrolytes (nEO:nLi = 16:1). The ionic conductivity of the PS-PEO-PS electrolyte at 80 °C is about one order of magnitude lower than that of the homopolymer (PEO) counterpart at the same temperature. However, the shear modulus (G’) of the PS-PEO-PS electrolyte is about three orders of magnitude higher than the homopolymer, indicating the mechanical properties of the copolymer electrolyte is primarily dominated by the PS phase. The addition of TEGDME plasticizer to the PEO homopolymer electrolyte resulted in a ~10% increase in conductivity. The addition of same amount of TEGDME to the PS-PEO-PS electrolyte resulted in ~100% increase in conductivity. Compared to the dry electrolyte counterpart, the low isothermal frequency (ω = 0.1 rad/s) elastic modulus, G’ of the TEGDME plastized PS-PEO-PS was reduced to half at 80 °C (on the order of 106 Pa). Surprisingly, G’ of the plastized membrane surpassed its dry PS-PEO-PS counterpart at higher frequency values (17 < ω < 100 rad/s). This counter intuitive result is further explored using: 1) Fourier-transform infrared spectroscopy (FTIR) to elucidate the salt solvation and coordination to ether oxygens, and 2) small angle X-ray scattering (SAXS) to decipher the domain spacing of the adjacent copolymer blocks. Acknowledgment This work is supported by Dr. Imre Gyuk, Manager, Energy Storage Program, Office of Electricity Delivery and Reliability, Department of Energy. CC acknowldge partial financial support by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

Noble Metal Decorated Anodic TiO2 Nanotubes: Excellent (Electro)Catalyst

The synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The most established member of this group of materials is nanoporous Al2O3, which has been prepared two decades ago by anodic oxidation of Al into perfectly ordered, honeycomb-like porous structures employing suitable electrochemical conditions [1]. Owing to the flexibility of the pore diameter/length and the relative ease of the Al2O3 dissolution, its porous membranes have been since than widely used as template material of choice for a range of materials [2-4]. Self-organized TiO2 nanotube layers have received the highest attention after Al2O3 motivated by its range of applications, including photocatalysis, water splitting, solar cells and biomedical uses. Very significant research efforts have led to reproducible synthesis of self-organized TiO2 nanotube layers by means of anodic oxidation, during which the starting Ti substrate is converted into a highly-ordered nanotubular layer by anodization in suitable electrolytes [5-8]. Many new applications can be derived upon modification of the nanotubes by decoration, filling or coating by secondary materials [9]. Atomic layer deposition (ALD) has been shown to be an effective technique to coat TiO2 nanotube layers homogenously with secondary materials or to decorate them with noble metals [9]. The resulting structures offer many advantages and opportunities in various applications. TiO2 nanotubes in particular appeal as highly ordered electron-conductive supports for noble metal particles. This presentation will focus in detail on the decoration of the nanotube layers of different aspect ratios by noble metals using ALD. We will show and discuss our recent catalytic results on water splitting [10] and electrocatalytic results on the oxidation of methanol [11].

Mussel-Inspired pH-Switched Assembly of Capsules with an Ultrathin and Robust Nanoshell.

Enclosed films, also called capsules, bearing an ultrathin and robust nanoshell have sparked much interest for use in many applications, for which facile preparation methods are urgently pursued. Inspired by the pH-programmed adhesion/cohesion of mussel-secreted foot proteins, polyphenol/polyamine capsules with an ultrathin and robust nanoshell are fabricated through a pH-switched assembly on sacrificial calcium carbonate (CaCO3) templates. Polyphenols adhere to the templates at pH 6.0 and rapidly cohere with polyamines at pH 8.0. The pH-switched assembly process is accomplished in only a few minutes where multiple instances of electrostatic interactions and chemical conjugation between polyphenols and polyamines occur. As a result, the capsules exhibit a nanoshell thickness of ∼10 nm and a superior mechanical strength of ∼1.575 GPa (elasticity modulus). Cell mimics are prepared through encasing enzymes in the lumen and present an activity recovery of ∼70% along with little activity decline during reuse. Amine or phenolic groups on the nanoshell of capsules are then applied to induce the generation of titania or silver nanoparticles, which may expand the applications of the capsules to the photo- and biorelated realms. Our study not only deepens the understanding of the adhering process of mussels but also offers a generic method toward functional materials for diverse applications.

Toward a Smart Compliant Robotic Gripper Equipped with 3D‐Designed Cellular Fingers

Usual lightweight soft robotic bodies built with elastomer materials show lack of structural stiffness that limits their use in many practical applications. Herein, an architectured robotic body design with deformable cellular structures, which is easy to fabricate, lightweight, mechanically durable, and compliant while maintaining its resilience, is proposed. The cellular body design overcomes not only the stiffness limitation but also other drawbacks of most common soft bodies that may damage from high pressure or impact. An artificial cellular finger is printed together with embedded pressure sensors on the fingertip to form a functional system in a single‐building process with the advantage of multi‐material 3D printing. The integrated architectured grippers, composed of cellular fingers with a repeatable, reliable bending profile, demonstrate maximum gripping force as 16 N on actuation, with gripping capability of various objects. 3D cellular designs open up new possibilities for architectured robotic bodies that can immensely widen their space of applications.

Synthesis, characterization and electrochemical properties of isoflavone substituted zinc(II), cobalt(II), and metal-free phthalocyanines

In this study, novel tetrasubstituted metallo- and metal-free phthalocyanines containing 7-hydroxy-4′-methoxyisoflavonoxy moieties at peripheral and non-peripheral positions have been prepared by cyclotetramerization of corresponding phthalonitriles. The most obvious feature of these quaternized complexes is their extensive solubility and non-aggregated species (especially non-peripherally substituted) in organic solvents such as chloroform, tetrahydrofuran, dimethylformamide and dimethylsulfoxide, which makes them candidates for use in many applications in different fields. The new compounds have been characterized by elemental analysis, FT-IR, UV-vis, 1H and [Formula: see text]C NMR and MS (Maldi-TOF MS). Voltammetric and in situ spectroelectrochemical measurements have been performed with the aim of characterizing the electron transfer properties of the compounds on Pt in dimethylsulfoxide/tetrabutylammonium perchlorate, compared to those of previously reported corresponding compounds with tetra 6-hydroxyflavonoxy substituents. The effect of aggregation on the redox character of these complexes was also discussed.

Extraction, chemical composition, and characterization of potential lignocellulosic biomasses and polymers from corn plant parts

Corn is a plant that can be used as a potential source of biomass for various biomaterial applications. Thermoplastic corn starch and corn hull, husk, and stalk fibers were extracted from different corn plant parts. The chemical composition, physical properties, thermal stability, crystallinity index, and surface morphology of the extracted samples were characterized on a powder basis. The corn husk and corn starch revealed an excellent combination of properties. Corn husk provided the highest cellulose content as well as the most favorable surface morphology. Corn starch revealed acceptable amylose content and tolerable thermal stability. The cellulose and starch demonstrated an excellent correlation between the function and structure of biomolecules. Hence, both corn starch and husk have potential for use in many applications of the biomaterial.

Acoustomicrofluidic assembly of oriented and simultaneously activated metal\u2013organic frameworks

The high surface area and porosity, and limitless compound and network combinations between the metal ions and organic ligands making up metal–organic frameworks (MOFs) offer tremendous opportunities for their use in many applications. While numerous methods have been proposed for the synthesis of MOF powders, it is often difficult to obtain oriented crystals with these techniques. Further, the need for additional post-synthesis steps to activate the crystals and release them from the substrate presents a considerable production challenge. Here, we report an acoustically-driven microcentrifugation platform that facilitates fast convective solutal transport, allowing the synthesis of MOF crystals in as short as five minutes. The crystals are not only oriented due to long-range out-of-plane superlattice ordering aided by molecular dipole polarization under the acoustoelectric coupling, but also simultaneously activated during the synthesis process.

Facile synthesis of nanostructured polyaniline in ionic liquids for high solubility and enhanced electrochemical properties

As one of the most investigated conducting polymers, polyaniline (PANI) is considered to be of practical use in many applications. In this study, two new ionic liquids, 1-methylimidazolium hydrogen sulfate ([Hmim]HSO4) and 1-methyl-3-n-butylimidazopersulfate ([C4mim]2S2O8), which were synthesized from 1-methylimidazole ([Hmim]), were used as solvent and dopant, oxidizer, respectively, for in situ polymerization of aniline. Because of the application of the unique structure of ionic liquid, we obtained the ionic liquid–doped polyaniline (IL-PANI) with high solubility (25 mg mL−1 in dimethyl sulfoxide (DMSO)). And by adjusting the ratio of [C4mim]2S2O8 to aniline monomer, the preferred PANI nanofibers could be controlled to form a three-dimensional porous structure. It was found that the ion/electron transport channels could be formed inside the 3D structure. Thus, the redox reactions could occur both at the surface and inside the PANI electrode. Electrochemical characterization showed that the fabricated PANI electrode exhibited a specific capacitance of 489 F g−1 at a current density of 0.5 A g−1. Also, the capacity retention rate reached up to 81% after 4000 cycles investigated at 2 A g−1. In addition, a high-energy density of 80.2 Wh kg−1 was measured when [Hmim]HSO4 was used as an electrolyte. Thus, the present work suggested a new strategy for fabricating high-performance PANI electrode for supercapacitor applications.

All-Silicon On-Chip Optical Nanoantennas as Efficient Interfaces for Plasmonic Devices

Plasmonic technology promises to unfold new advanced on-chip functionalities with direct applications in photovoltaics, light–matter interaction, and the miniaturization of optical interconnects at the nanoscale. In this scenario, it is crucial to efficiently drive light to/from plasmonic devices. However, typically used plasmonic wires introduce prohibitive losses, hampering their use for many applications. Recently, plasmonic nanoantennas have been proposed to overcome this drawback, not only providing a notable loss reduction, but also an enhanced on-chip flexibility and reconfigurability. Nevertheless, these devices still perform poorly for long-reach interconnects, owing to their low-directive radiation and low efficiency. Here, we introduce a class of slot-waveguide-based silicon nanoantennas that lift all these limitations and show their feasibility to be connected directly and efficiently to plasmonic devices. To test the performance of these antennae, an on-chip plasmonic-dielectric interconnect ...

Recent Progress with Next Generation High-Speed Ethernet Optical Device Technology

Ethernet has become an indispensable technology for communications, and has come into use for many applications. At the IEEE, high-speed standardization has been discussed and has seen the adoption of new technologies such as multi-level modulation formats, high baud rate modulation and dense wave length division multiplexing. The MSA transceiver form factor has also been discussed following IEEE standardization. Optical devices such as TOSA and ROSA have been required to become more compact and higher-speed, because each transceiver form factor has to be miniaturized for high-density construction. We introduce the technologies for realizing 100GbE and those applicable to 400GbE. We also discuss future packages for optical devices. There are many similarities between optical device packages and electrical device packages, and we predict that optical device packages will follow the trends seen in electrical devices. But there are also differences between optical and electrical devices. It is necessary to utilize new technology for specific optical issues to employ advanced electrical packaging and catch up the trends.

The Role of Ligands in the Chemical Synthesis and Applications of Inorganic Nanoparticles.

The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

GPU acceleration of the KAZE image feature extraction algorithm

The recently proposed, KAZE image feature detection and description algorithm (Alcantarilla et al. in Proceedings of the British machine vision conference. LNCS, vol 7577, no 6, pp 13.1–13.11, 2013) offers significantly improved robustness in comparison to conventional algorithms like SIFT (scale-invariant feature transform) and SURF (speeded-up robust features). The improved robustness comes at a significant computational cost, however, limiting its use for many applications. We report a GPU acceleration of the KAZE algorithm that is significantly faster than its CPU counterpart. Unlike previous reports, our acceleration does not resort to binary descriptors and can serve as a drop-in replacement for CPU-KAZE, SIFT, SURF etc. By achieving nearly tenfold speedup (for a 1920 by 1200 sized image, our Compute Unified Device Architecture (CUDA)-C implementation took around 245 ms on a single GPU in comparison to nearly 2400 ms for a 16-threaded CPU version) without degradation in feature extraction performance, our work expands the applicability of the KAZE algorithm. Additionally, the strategies described here could also prove useful for the GPU implementation of other nonlinear scale-space-based image processing algorithms.

Bioengineering adult human heart tissue: How close are we?

Human pluripotent stem cells (hPSCs) have extensive applications in fundamental biology, regenerative medicine, disease modelling, and drug discovery/toxicology. Whilst large numbers of cardiomyocytes can be generated from hPSCs, extensive characterization has revealed that they have immature cardiac properties. This has raised potential concerns over their usefulness for many applications and has led to the pursuit of driving maturation of hPSC-cardiomyocytes. Currently, the best approach for driving maturity is the use of tissue engineering to generate highly functional three-dimensional heart tissue. Although we have made significant progress in this area, we have still not generated heart tissue that fully recapitulates all the properties of an adult heart. Deciphering the processes driving cardiomyocyte maturation will be instrumental in uncovering the mechanisms that govern optimal heart function and identifying new therapeutic targets for heart disease.

Electrical Properties of Ultrathin Platinum Films by Plasma-Enhanced Atomic Layer Deposition

The ability to deposit thin and conformal films has become of great importance because of downscaling of devices. However, because of nucleation difficulty, depositing an electrically stable and thin conformal platinum film on an oxide nucleation layer has proven challenging. By using plasma-enhanced atomic layer deposition (PEALD) and TiO2 as a nucleation layer, we achieved electrically continuous PEALD platinum films down to a thickness of 3.7 nm. Results show that for films as thin as 5.7 nm, the Mayadas–Shatzkes (MS) model for electrical conductivity and the Tellier–Tosser model for temperature coefficient of resistance hold. Although the experimental values start to deviate from the MS model below 5.7 nm because of incomplete Pt coverage, the films still show root mean square electrical stability better than 50 ppm over time, indicating that these films are not only electrically continuous but also sufficiently reliable for use in many practical applications.