Phonon Avoided and Scalable Cascade Lasers (PASCAL)

DTIC Science & Technology

2008-11-01

up We fully developed the mask-less nanolithography technique. The SEM micrographs show that highly uniform nanoholes and nanopillars array can be...by the technique and we produced a large area of high uniform nanoholes perforated in Al films, which is a big step towards making quantum dot...spheres on photoresist ’ • A. W A - " > EN • • • ^Ti—i Figure 14 - SEM images series showing nanoholes generated with

Economic consequences of high throughput maskless lithography

NASA Astrophysics Data System (ADS)

Hartley, John G.; Govindaraju, Lakshmi

2005-11-01

Many people in the semiconductor industry bemoan the high costs of masks and view mask cost as one of the significant barriers to bringing new chip designs to market. All that is needed is a viable maskless technology and the problem will go away. Numerous sites around the world are working on maskless lithography but inevitably, the question asked is "Wouldn't a one wafer per hour maskless tool make a really good mask writer?" Of course, the answer is yes, the hesitation you hear in the answer isn't based on technology concerns, it's financial. The industry needs maskless lithography because mask costs are too high. Mask costs are too high because mask pattern generators (PG's) are slow and expensive. If mask PG's become much faster, mask costs go down, the maskless market goes away and the PG supplier is faced with an even smaller tool demand from the mask shops. Technical success becomes financial suicide - or does it? In this paper we will present the results of a model that examines some of the consequences of introducing high throughput maskless pattern generation. Specific features in the model include tool throughput for masks and wafers, market segmentation by node for masks and wafers and mask cost as an entry barrier to new chip designs. How does the availability of low cost masks and maskless tools affect the industries tool makeup and what is the ultimate potential market for high throughput maskless pattern generators?

High sensitive virus and bacteria detection using plasma-surface-functionalized and antibody-integrated carbon nanomaterials

NASA Astrophysics Data System (ADS)

Nagatsu, Masaaki

2015-09-01

In this study we will present our recent results on the virus and bacteria detection system using the surface-functionalized carbon-encapsulated magnetic nanoparticles (NPs) fabricated by dc arc discharge, and carbon nanotube(CNT) dot-array prepared with a combined thermal and plasma CVD system. Surface functionalization of their surfaces has been carried out by plasma chemical modification using a low-pressure RF plasma for carbon-encapsulated magnetic NPs, and an ultrafine atmospheric pressure plasma jet(APPJ) for CNT dot-array substrate. After immobilization of the relevant biomolecules onto the surface of nano-structured materials, we have carried out the experiments on virus or bacteria detection using these surface-functionalized nano-structured materials. From the preliminary experiments with carbon-encapsulated magnetic NPs, we confirmed that influenza A (H1N1) virus concentration of 17.3-fold was achieved by using anti-influenza A virus hemagglutinin (HA) antibody. We have also confirmed a rapid and sensitive detection of Salmonella using the proposed method. The feasibility of CNT dot-array as a microarray biosensor has been studied by maskless functionalization of amino (-NH2) and carboxyl (-COOH) groups onto CNTs by using a ultrafine APPJ with a micro-capillary. The experimental results of chemical derivatization with the fluorescent dye showed that the CNT dot-array was not only functionalized with amino group and carboxyl group, but was also functionalized without any interference between functional groups. The success of maskless functionalization in the line pattern provides a feasibility of a multi-functionalization CNT dot-array device for future application of a microarray biosensor. This work has been supported in part by Grant-in-Aid for Scientific Research (Nos. 21110010 and 25246029) from the JSPS and the International Research Collaboration and Scientific Publication Grant (DIPA-23.04.1.673453/2015) from DGHE Indonesia.

OML: optical maskless lithography for economic design prototyping and small-volume production

NASA Astrophysics Data System (ADS)

Sandstrom, Tor; Bleeker, Arno; Hintersteiner, Jason; Troost, Kars; Freyer, Jorge; van der Mast, Karel

2004-05-01

The business case for Maskless Lithography is more compelling than ever before, due to more critical processes, rising mask costs and shorter product cycles. The economics of Maskless Lithography gives a crossover volume from Maskless to mask-based lithography at surprisingly many wafers per mask for surprisingly few wafers per hour throughput. Also, small-volume production will in many cases be more economical with Maskless Lithography, even when compared to "shuttle" schemes, reticles with multiple layers, etc. The full benefit of Maskless Lithography is only achievable by duplicating processes that are compatible with volume production processes on conventional scanners. This can be accomplished by the integration of pattern generators based on spatial light modulator technology with state-of-the-art optical scanner systems. This paper reports on the system design of an Optical Maskless Scanner in development by ASML and Micronic: small-field optics with high demagnification, variable NA and illumination schemes, spatial light modulators with millions of MEMS mirrors on CMOS drivers, a data path with a sustained data flow of more than 250 GPixels per second, stitching of sub-fields to scanner fields, and rasterization and writing strategies for throughput and good image fidelity. Predicted lithographic performance based on image simulations is also shown.

Silver nanowire/polymer composite soft conductive film fabricated by large-area compatible coating for flexible pressure sensor array

NASA Astrophysics Data System (ADS)

Chen, Sujie; Li, Siying; Peng, Sai; Huang, Yukun; Zhao, Jiaqing; Tang, Wei; Guo, Xiaojun

2018-01-01

Soft conductive films composed of a silver nanowire (AgNW) network, a neutral-pH PEDOT:PSS over-coating layer and a polydimethylsiloxane (PDMS) elastomer substrate are fabricated by large area compatible coating processes. The neutral-pH PEDOT:PSS layer is shown to be able to significantly improve the conductivity, stretchability and air stability of the conductive films. The soft conductive films are patterned using a simple maskless patterning approach to fabricate an 8 × 8 flexible pressure sensor array. It is shown that such soft conductive films can help to improve the sensitivity and reduce the signal crosstalk over the pressure sensor array. Project supported by the Science and Technology Commission of Shanghai Municipality (No. 16JC1400603).

Lossless compression techniques for maskless lithography data

NASA Astrophysics Data System (ADS)

Dai, Vito; Zakhor, Avideh

2002-07-01

Future lithography systems must produce more dense chips with smaller feature sizes, while maintaining the throughput of one wafer per sixty seconds per layer achieved by today's optical lithography systems. To achieve this throughput with a direct-write maskless lithography system, using 25 nm pixels for 50 nm feature sizes, requires data rates of about 10 Tb/s. In a previous paper, we presented an architecture which achieves this data rate contingent on consistent 25 to 1 compression of lithography data, and on implementation of a decoder-writer chip with a real-time decompressor fabricated on the same chip as the massively parallel array of lithography writers. In this paper, we examine the compression efficiency of a spectrum of techniques suitable for lithography data, including two industry standards JBIG and JPEG-LS, a wavelet based technique SPIHT, general file compression techniques ZIP and BZIP2, our own 2D-LZ technique, and a simple list-of-rectangles representation RECT. Layouts rasterized both to black-and-white pixels, and to 32 level gray pixels are considered. Based on compression efficiency, JBIG, ZIP, 2D-LZ, and BZIP2 are found to be strong candidates for application to maskless lithography data, in many cases far exceeding the required compression ratio of 25. To demonstrate the feasibility of implementing the decoder-writer chip, we consider the design of a hardware decoder based on ZIP, the simplest of the four candidate techniques. The basic algorithm behind ZIP compression is Lempel-Ziv 1977 (LZ77), and the design parameters of LZ77 decompression are optimized to minimize circuit usage while maintaining compression efficiency.

Simple fabrication of closed-packed IR microlens arrays on silicon by femtosecond laser wet etching

NASA Astrophysics Data System (ADS)

Meng, Xiangwei; Chen, Feng; Yang, Qing; Bian, Hao; Du, Guangqing; Hou, Xun

2015-10-01

We demonstrate a simple route to fabricate closed-packed infrared (IR) silicon microlens arrays (MLAs) based on femtosecond laser irradiation assisted by wet etching method. The fabricated MLAs show high fill factor, smooth surface and good uniformity. They can be used as optical devices for IR applications. The exposure and etching parameters are optimized to obtain reproducible microlens with hexagonal and rectangular arrangements. The surface roughness of the concave MLAs is only 56 nm. This presented method is a maskless process and can flexibly change the size, shape and the fill factor of the MLAs by controlling the experimental parameters. The concave MLAs on silicon can work in IR region and can be used for IR sensors and imaging applications.

Optofluidic encapsulation and manipulation of silicon microchips using image processing based optofluidic maskless lithography and railed microfluidics.

PubMed

Chung, Su Eun; Lee, Seung Ah; Kim, Jiyun; Kwon, Sunghoon

2009-10-07

We demonstrate optofluidic encapsulation of silicon microchips using image processing based optofluidic maskless lithography and manipulation using railed microfluidics. Optofluidic maskless lithography is a dynamic photopolymerization technique of free-floating microstructures within a fluidic channel using spatial light modulator. Using optofluidic maskless lithography via computer-vision aided image processing, polymer encapsulants are fabricated for chip protection and guiding-fins for efficient chip conveying within a fluidic channel. Encapsulated silicon chips with guiding-fins are assembled using railed microfluidics, which is an efficient guiding and heterogeneous self-assembly system of microcomponents. With our technology, externally fabricated silicon microchips are encapsulated, fluidically guided and self-assembled potentially enabling low cost fluidic manipulation and assembly of integrated circuits.

M3: Microscope-based maskless micropatterning with dry film photoresist

PubMed Central

Leigh, Steven Y.; Tattu, Aashay; Mitchell, Joseph S. B.

2011-01-01

We present a maskless micropatterning system that utilizes a fluorescence microscope with programmable X-Y stage and dry film photoresist to realize feature sizes in the sub-millimeter range (40–700 μm). The method allows for flexible in-house maskless photolithography without a dedicated microfabrication facility and is well-suited for rapid prototyping of microfluidic channels, scaffold templates for protein/cell patterning or optically-guided cell encapsulation for biomedical applications. PMID:21190086

Manufacture of Micromirror Arrays Using a CMOS-MEMS Technique

PubMed Central

Kao, Pin-Hsu; Dai, Ching-Liang; Hsu, Cheng-Chih; Wu, Chyan-Chyi

2009-01-01

In this study we used the commercial 0.35 μm CMOS (complementary metal oxide semiconductor) process and simple maskless post-processing to fabricate an array of micromirrors exhibiting high natural frequency. The micromirrors were manufactured from aluminum; the sacrificial layer was silicon dioxide. Because we fabricated the micromirror arrays using the standard CMOS process, they have the potential to be integrated with circuitry on a chip. For post-processing we used an etchant to remove the sacrificial layer and thereby suspend the micromirrors. The micromirror array contained a circular membrane and four fixed beams set symmetrically around and below the circular mirror; these four fan-shaped electrodes controlled the tilting of the micromirror. A MEMS (microelectromechanical system) motion analysis system and a confocal 3D-surface topography were used to characterize the properties and configuration of the micromirror array. Each micromirror could be rotated in four independent directions. Experimentally, we found that the micromirror had a tilting angle of about 2.55° when applying a driving voltage of 40 V. The natural frequency of the micromirrors was 59.1 kHz. PMID:22454581

Manufacture of Micromirror Arrays Using a CMOS-MEMS Technique.

PubMed

Kao, Pin-Hsu; Dai, Ching-Liang; Hsu, Cheng-Chih; Wu, Chyan-Chyi

2009-01-01

In this study we used the commercial 0.35 μm CMOS (complementary metal oxide semiconductor) process and simple maskless post-processing to fabricate an array of micromirrors exhibiting high natural frequency. The micromirrors were manufactured from aluminum; the sacrificial layer was silicon dioxide. Because we fabricated the micromirror arrays using the standard CMOS process, they have the potential to be integrated with circuitry on a chip. For post-processing we used an etchant to remove the sacrificial layer and thereby suspend the micromirrors. The micromirror array contained a circular membrane and four fixed beams set symmetrically around and below the circular mirror; these four fan-shaped electrodes controlled the tilting of the micromirror. A MEMS (microelectromechanical system) motion analysis system and a confocal 3D-surface topography were used to characterize the properties and configuration of the micromirror array. Each micromirror could be rotated in four independent directions. Experimentally, we found that the micromirror had a tilting angle of about 2.55° when applying a driving voltage of 40 V. The natural frequency of the micromirrors was 59.1 kHz.

Diamond field emitter array cathodes and possibilities of employing additive manufacturing for dielectric laser accelerating structures

NASA Astrophysics Data System (ADS)

Simakov, Evgenya I.; Andrews, Heather L.; Herman, Matthew J.; Hubbard, Kevin M.; Weis, Eric

2017-03-01

Demonstration of a stand-alone practical dielectric laser accelerator (DLA) requires innovation in two major critical components: high-current ultra-low-emittance cathodes and efficient laser accelerator structures. LANL develops two technologies that in our opinion are applicable to the novel DLA architectures: diamond field emitter array (DFEA) cathodes and additive manufacturing of photonic band-gap (PBG) structures. This paper discusses the results of testing of DFEA cathodes in the field-emission regime and the possibilities for their operation in the photoemission regime, and compares their emission characteristics to the specific needs of DLAs. We also describe recent advances in additive manufacturing of dielectric woodpile structures using a Nanoscribe direct laser-writing device capable of maskless lithography and additive manufacturing, and the development of novel infrared dielectric materials compatible with additive manufacturing.

Advances in maskless and mask-based optical lithography on plastic flexible substrates

NASA Astrophysics Data System (ADS)

Barbu, Ionut; Ivan, Marius G.; Giesen, Peter; Van de Moosdijk, Michel; Meinders, Erwin R.

2009-12-01

Organic flexible electronics is an emerging technology with huge potential growth in the future which is likely to open up a complete new series of potential applications such as flexible OLED-based displays, urban commercial signage, and flexible electronic paper. The transistor is the fundamental building block of all these applications. A key challenge in patterning transistors on flexible plastic substrates stems from the in-plane nonlinear deformations as a consequence of foil expansion/shrinkage, moisture uptake, baking etc. during various processing steps. Optical maskless lithography is one of the potential candidates for compensating for these foil distortions by in-situ adjustment prior to exposure of the new layer image with respect to the already patterned layers. Maskless lithography also brings the added value of reducing the cost-of-ownership related to traditional mask-based tools by eliminating the need for expensive masks. For the purpose of this paper, single-layer maskless exposures at 355 nm were performed on gold-coated poly(ethylenenaphthalate) (PEN) flexible substrates temporarily attached to rigid carriers to ensure dimensional stability during processing. Two positive photoresists were employed for this study and the results on plastic foils were benchmarked against maskless as well as mask-based (ASML PAS 5500/100D stepper) exposures on silicon wafers.

Stitch overlap via coloring technique enables maskless via

NASA Astrophysics Data System (ADS)

Civay, D.; Laffosse, E.

2017-03-01

Lithographic patterning limits can be a cost-barrier that delays advancement to new nodes. This paper introduces a cost-saving design method that enables a maskless via. Multi-patterning or coloring of a design is a technique that is used at advanced nodes to aid in patterning. Coloring allows designers to designate different patterns on one level to be printed with different masks. Stitch overlap via (SOV) is a coloring technique introduced herein. SOV utilizes via-aware coloring and a unique process flow to print a maskless via. Identification of qualifying design structures is achieved through a custom program. The program inputs the design level of the multipatterned layer and the via levels above and below to determine the coloring decomposition. Vias are a particularly challenging layer to print due to the dimensions required for these pillars. SOV is a methodology for identifying qualifying multi-patterned layouts and replacing them with a new design that enables a maskless via layer.

Maskless, reticle-free, lithography

DOEpatents

Ceglio, N.M.; Markle, D.A.

1997-11-25

A lithography system in which the mask or reticle, which usually carries the pattern to be printed onto a substrate, is replaced by a programmable array of binary (i.e. on/off) light valves or switches which can be programmed to replicate a portion of the pattern each time an illuminating light source is flashed. The pattern of light produced by the programmable array is imaged onto a lithographic substrate which is mounted on a scanning stage as is common in optical lithography. The stage motion and the pattern of light displayed by the programmable array are precisely synchronized with the flashing illumination system so that each flash accurately positions the image of the pattern on the substrate. This is achieved by advancing the pattern held in the programmable array by an amount which corresponds to the travel of the substrate stage each time the light source flashes. In this manner the image is built up of multiple flashes and an isolated defect in the array will only have a small effect on the printed pattern. The method includes projection lithographies using radiation other than optical or ultraviolet light. The programmable array of binary switches would be used to control extreme ultraviolet (EUV), x-ray, or electron, illumination systems, obviating the need for stable, defect free masks for projection EUV, x-ray, or electron, lithographies. 7 figs.

Maskless, reticle-free, lithography

DOEpatents

Ceglio, Natale M.; Markle, David A.

1997-11-25

A lithography system in which the mask or reticle, which usually carries the pattern to be printed onto a substrate, is replaced by a programmable array of binary (i.e. on/off) light valves or switches which can be programmed to replicate a portion of the pattern each time an illuminating light source is flashed. The pattern of light produced by the programmable array is imaged onto a lithographic substrate which is mounted on a scanning stage as is common in optical lithography. The stage motion and the pattern of light displayed by the programmable array are precisely synchronized with the flashing illumination system so that each flash accurately positions the image of the pattern on the substrate. This is achieved by advancing the pattern held in the programmable array by an amount which corresponds to the travel of the substrate stage each time the light source flashes. In this manner the image is built up of multiple flashes and an isolated defect in the array will only have a small effect on the printed pattern. The method includes projection lithographies using radiation other than optical or ultraviolet light. The programmable array of binary switches would be used to control extreme ultraviolet (EUV), x-ray, or electron, illumination systems, obviating the need for stable, defect free masks for projection EUV, x-ray, or electron, lithographies.

Design and fabrication of a diffractive beam splitter for dual-wavelength and concurrent irradiation of process points.

PubMed

Amako, Jun; Shinozaki, Yu

2016-07-11

We report on a dual-wavelength diffractive beam splitter designed for use in parallel laser processing. This novel optical element generates two beam arrays of different wavelengths and allows their overlap at the process points on a workpiece. To design the deep surface-relief profile of a splitter using a simulated annealing algorithm, we introduce a heuristic but practical scheme to determine the maximum depth and the number of quantization levels. The designed corrugations were fabricated in a photoresist by maskless grayscale exposure using a high-resolution spatial light modulator. We characterized the photoresist splitter, thereby validating the proposed beam-splitting concept.

Scalable maskless patterning of nanostructures using high-speed scanning probe arrays

NASA Astrophysics Data System (ADS)

Chen, Chen; Akella, Meghana; Du, Zhidong; Pan, Liang

2017-08-01

Nanoscale patterning is the key process to manufacture important products such as semiconductor microprocessors and data storage devices. Many studies have shown that it has the potential to revolutionize the functions of a broad range of products for a wide variety of applications in energy, healthcare, civil, defense and security. However, tools for mass production of these devices usually cost tens of million dollars each and are only affordable to the established semiconductor industry. A new method, nominally known as "pattern-on-the- y", that involves scanning an array of optical or electrical probes at high speed to form nanostructures and offers a new low-cost approach for nanoscale additive patterning. In this paper, we report some progress on using this method to pattern self-assembled monolayers (SAMs) on silicon substrate. We also functionalize the substrate with gold nanoparticle based on the SAM to show the feasibility of preparing amphiphilic and multi-functional surfaces.

Optimization of printing techniques for electrochemical biosensors

NASA Astrophysics Data System (ADS)

Zainuddin, Ahmad Anwar; Mansor, Ahmad Fairuzabadi Mohd; Rahim, Rosminazuin Ab; Nordin, Anis Nurashikin

2017-03-01

Electrochemical biosensors show great promise for point-of-care applications due to their low cost, portability and compatibility with microfluidics. The miniature size of these sensors provides advantages in terms of sensitivity, specificity and allows them to be mass produced in arrays. The most reliable fabrication technique for these sensors is lithography followed by metal deposition using sputtering or chemical vapor deposition techniques. This technique which is usually done in the cleanroom requires expensive masking followed by deposition. Recently, cheaper printing techniques such as screen-printing and ink-jet printing have become popular due to its low cost, ease of fabrication and mask-less method. In this paper, two different printing techniques namely inkjet and screen printing are demonstrated for an electrochemical biosensor. For ink-jet printing technique, optimization of key printing parameters, such as pulse voltages, drop spacing and waveform setting, in-house temperature and cure annealing for obtaining the high quality droplets, are discussed. These factors are compared with screen-printing parameters such as mesh size, emulsion thickness, minimum spacing of lines and curing times. The reliability and reproducibility of the sensors are evaluated using scotch tape test, resistivity and profile-meter measurements. It was found that inkjet printing is superior because it is mask-less, has minimum resolution of 100 µm compared to 200 µm for screen printing and higher reproducibility rate of 90% compared to 78% for screen printing.

Direct-write maskless lithography using patterned oxidation of Si-substrate Induced by femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Kiani, Amirkianoosh; Venkatakrishnan, Krishnan; Tan, Bo

2013-03-01

In this study we report a new method for direct-write maskless lithography using oxidized silicon layer induced by high repetition (MHz) ultrafast (femtosecond) laser pulses under ambient condition. The induced thin layer of predetermined pattern can act as an etch stop during etching process in alkaline etchants such as KOH. The proposed method can be leading to promising solutions for direct-write maskless lithography technique since the proposed method offers a higher degree of flexibility and reduced time and cost of fabrication which makes it particularly appropriate for rapid prototyping and custom scale manufacturing. A Scanning Electron Microscope (SEM), Micro-Raman, Energy Dispersive X-ray (EDX), optical microscope and X-ray diffraction spectroscopy (XRD) were used to evaluate the quality of oxidized layer induced by laser pulses.

Inkjet-Print Micromagnet Array on Glass Slides for Immunomagnetic Enrichment of Circulating Tumor Cells

PubMed Central

Chen, Peng; Huang, Yu-Yen; Bhave, Gauri; Hoshino, Kazunori; Zhang, Xiaojing

2015-01-01

We report an inkjet-printed microscale magnetic structure that can be integrated on regular glass slides for the immunomagnetic screening of rare Circulating Tumor Cells (CTCs). CTCs detach from the primary tumor site, circulate with the bloodstream, and initiate the cancer metastasis process. Therefore, a liquid biopsy in the form of capturing and analyzing CTCs may provide key information for cancer prognosis and diagnosis. Inkjet printing technology provides a non-contact, layer-by-layer and mask-less approach to deposit defined magnetic patterns on an arbitrary substrate. Such thin film patterns, when placed in an external magnetic field, significantly enhance the attractive force in the near-field close to the CTCs to facilitate the separation. We demonstrated the efficacy of the inkjet-print micromagnet array integrated immunomagnetic assay in separating COLO205 (human colorectal cancer cell line) from whole blood samples. The micromagnets increased the capture efficiency by 26% compared with using plain glass slide as the substrate. PMID:26289942

Flexible fabrication of biomimetic compound eye array via two-step thermal reflow of simply pre-modeled hierarchic microstructures

NASA Astrophysics Data System (ADS)

Huang, Shengzhou; Li, Mujun; Shen, Lianguan; Qiu, Jinfeng; Zhou, Youquan

2017-06-01

A flexible fabrication method for the biomimetic compound eye (BCE) array is proposed. In this method, a triple-layer sandwich-like coating configuration was introduced, and the required hierarchic microstructures are formed with a simple single-scan exposure in maskless digital lithography. Taking advantage of the difference of glass transition point (Tg) between photoresists of each layer, the pre-formed hierarchic microstructures are in turn reflowed to the curved substrate and the BCE ommatidia in a two-step thermal reflow process. To avoid affecting the spherical substrate formed in the first thermal reflow, a non-contact strategy was proposed in the second reflow process. The measurement results were in good agreement with the designed BCE profiles. Results also showed that the fabricated BCE had good performances in optical test. The presented method is flexible, convenient, low-cost and can easily adapt to the fabrications of other optical elements with hierarchic microstructures.

Morphology modulating the wettability of a diamond film.

PubMed

Tian, Shibing; Sun, Weijie; Hu, Zhaosheng; Quan, Baogang; Xia, Xiaoxiang; Li, Yunlong; Han, Dong; Li, Junjie; Gu, Changzhi

2014-10-28

Control of the wetting property of diamond surface has been a challenge because of its maximal hardness and good chemical inertness. In this work, the micro/nanoarray structures etched into diamond film surfaces by a maskless plasma method are shown to fix a surface's wettability characteristics, and this means that the change in morphology is able to modulate the wettability of a diamond film from weakly hydrophilic to either superhydrophilic or superhydrophobic. It can be seen that the etched diamond surface with a mushroom-shaped array is superhydrophobic following the Cassie mode, whereas the etched surface with nanocone arrays is superhydrophilic in accordance with the hemiwicking mechnism. In addition, the difference in cone densities of superhydrophilic nanocone surfaces has a significant effect on water spreading, which is mainly derived from different driving forces. This low-cost and convenient means of altering the wetting properties of diamond surfaces can be further applied to underlying wetting phenomena and expand the applications of diamond in various fields.

Fabrication of high quality aspheric microlens array by dose-modulated lithography and surface thermal reflow

NASA Astrophysics Data System (ADS)

Huang, Shengzhou; Li, Mujun; Shen, Lianguan; Qiu, Jinfeng; Zhou, Youquan

2018-03-01

A novel fabrication method for high quality aspheric microlens array (MLA) was developed by combining the dose-modulated DMD-based lithography and surface thermal reflow process. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography. And the dose modulation mainly depends on the distribution of exposure dose of photoresist. Then the pre-shaped aspheric microlens is polished by a following non-contact thermal reflow (NCTR) process. Different from the normal process, the reflow process here is investigated to improve the surface quality while keeping the pre-modeled shape unchanged, and thus will avoid the difficulties in generating the aspheric surface during reflow. Fabrication of a designed aspheric MLA with this method was demonstrated in experiments. Results showed that the obtained aspheric MLA was good in both shape accuracy and surface quality. The presented method may be a promising approach in rapidly fabricating high quality aspheric microlens with complex surface.

Electrochemically induced maskless metal deposition on micropore wall.

PubMed

Liu, Jie; Hébert, Clément; Pham, Pascale; Sauter-Starace, Fabien; Haguet, Vincent; Livache, Thierry; Mailley, Pascal

2012-05-07

By applying an external electric field across a micropore via an electrolyte, metal ions in the electrolyte can be reduced locally onto the inner wall of the micropore, which was fabricated in a silica-covered silicon membrane. This maskless metal deposition on the silica surface is a result of the pore membrane polarization in the electric field. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Maskless Lithography Using Negative Photoresist Material: Impact of UV Laser Intensity on the Cured Line Width

NASA Astrophysics Data System (ADS)

Mohammed, Mohammed Ziauddin; Mourad, Abdel-Hamid I.; Khashan, Saud A.

2018-06-01

The application of maskless lithography technique on negative photoresist material is investigated in this study. The equipment used in this work is designed and built especially for maskless lithography applications. The UV laser of 405 nm wavelength with 0.85 Numerical Aperture is selected for direct laser writing. All the samples are prepared on a glass substrate. Samples are tested at different UV laser intensities and different stage velocities in order to study the impact on patterned line width. Three cases of spin coated layers of thickness 90 μm, 40 μm, and 28 μm on the substrate are studied. The experimental results show that line width has a generally increasing trend with intensity. However, a decreasing trend was observed for increasing velocity. The overall performance shows that the mr-DWL material is suitable for direct laser writing systems.

Maskless Lithography Using Negative Photoresist Material: Impact of UV Laser Intensity on the Cured Line Width

NASA Astrophysics Data System (ADS)

Mohammed, Mohammed Ziauddin; Mourad, Abdel-Hamid I.; Khashan, Saud A.

2018-04-01

The application of maskless lithography technique on negative photoresist material is investigated in this study. The equipment used in this work is designed and built especially for maskless lithography applications. The UV laser of 405 nm wavelength with 0.85 Numerical Aperture is selected for direct laser writing. All the samples are prepared on a glass substrate. Samples are tested at different UV laser intensities and different stage velocities in order to study the impact on patterned line width. Three cases of spin coated layers of thickness 90 μm, 40 μm, and 28 μm on the substrate are studied. The experimental results show that line width has a generally increasing trend with intensity. However, a decreasing trend was observed for increasing velocity. The overall performance shows that the mr-DWL material is suitable for direct laser writing systems.

Modulated grayscale UV pattern for uniform photopolymerization based on a digital micromirror device system

NASA Astrophysics Data System (ADS)

Yoon, Jinsik; Kim, Kibeom; Park, Wook

2017-07-01

We present an essential method for generating microparticles uniformly in a single ultraviolet (UV) light exposure area for optofluidic maskless lithography. In the optofluidic maskless lithography process, the productivity of monodisperse microparticles depends on the size of the UV exposure area. An effective fabrication area is determined by the size of the UV intensity profile map, satisfying the required uniformity of UV intensity. To increase the productivity of monodisperse microparticles in optofluidic maskless lithography, we expanded the effective UV exposure area by modulating the intensity of the desired UV light pattern based on the premeasured UV intensity profile map. We verified the improvement of the uniformity of the microparticles generated by the proposed modulation technique, providing histogram analyses of the conjugated fluorescent intensities and the sizes of the microparticles. Additionally, we demonstrated the generation of DNA uniformly encapsulated in microparticles.

Toward all-carbon electronics: fabrication of graphene-based flexible electronic circuits and memory cards using maskless laser direct writing.

PubMed

Liang, Jiajie; Chen, Yongsheng; Xu, Yanfei; Liu, Zhibo; Zhang, Long; Zhao, Xin; Zhang, Xiaoliang; Tian, Jianguo; Huang, Yi; Ma, Yanfeng; Li, Feifei

2010-11-01

Owing to its extraordinary electronic property, chemical stability, and unique two-dimensional nanostructure, graphene is being considered as an ideal material for the highly expected all-carbon-based micro/nanoscale electronics. Herein, we present a simple yet versatile approach to constructing all-carbon micro/nanoelectronics using solution-processing graphene films directly. From these graphene films, various graphene-based microcosmic patterns and structures have been fabricated using maskless computer-controlled laser cutting. Furthermore, a complete system involving a prototype of a flexible write-once-read-many-times memory card and a fast data-reading system has been demonstrated, with infinite data retention time and high reliability. These results indicate that graphene could be the ideal material for fabricating the highly demanded all-carbon and flexible devices and electronics using the simple and efficient roll-to-roll printing process when combined with maskless direct data writing.

Ion beam lithography system

DOEpatents

Leung, Ka-Ngo

2005-08-02

A maskless plasma-formed ion beam lithography tool provides for patterning of sub-50 nm features on large area flat or curved substrate surfaces. The system is very compact and does not require an accelerator column and electrostatic beam scanning components. The patterns are formed by switching beamlets on or off from a two electrode blanking system with the substrate being scanned mechanically in one dimension. This arrangement can provide a maskless nano-beam lithography tool for economic and high throughput processing.

Maskless micro-ion-beam reduction lithography system

DOEpatents

Leung, Ka-Ngo; Barletta, William A.; Patterson, David O.; Gough, Richard A.

2005-05-03

A maskless micro-ion-beam reduction lithography system is a system for projecting patterns onto a resist layer on a wafer with feature size down to below 100 nm. The MMRL system operates without a stencil mask. The patterns are generated by switching beamlets on and off from a two electrode blanking system or pattern generator. The pattern generator controllably extracts the beamlet pattern from an ion source and is followed by a beam reduction and acceleration column.

Digital selective growth of a ZnO nanowire array by large scale laser decomposition of zinc acetate.

PubMed

Hong, Sukjoon; Yeo, Junyeob; Manorotkul, Wanit; Kang, Hyun Wook; Lee, Jinhwan; Han, Seungyong; Rho, Yoonsoo; Suh, Young Duk; Sung, Hyung Jin; Ko, Seung Hwan

2013-05-07

We develop a digital direct writing method for ZnO NW micro-patterned growth on a large scale by selective laser decomposition of zinc acetate. For ZnO NW growth, by replacing the bulk heating with the scanning focused laser as a fully digital local heat source, zinc acetate crystallites can be selectively activated as a ZnO seed pattern to grow ZnO nanowires locally on a larger area. Together with the selective laser sintering process of metal nanoparticles, more than 10,000 UV sensors have been demonstrated on a 4 cm × 4 cm glass substrate to develop all-solution processible, all-laser mask-less digital fabrication of electronic devices including active layer and metal electrodes without any conventional vacuum deposition, photolithographic process, premade mask, high temperature and vacuum environment.

Strong light absorption capability directed by structured profile of vertical Si nanowires

NASA Astrophysics Data System (ADS)

Chaliyawala, Harsh A.; Ray, Abhijit; Pati, Ranjan K.; Mukhopadhyay, Indrajit

2017-11-01

Si nanowire arrays (SiNWAs) with random fractal geometry was fabricated using fast, mask-less, non-lithographic and facile approach by incorporating metal assisted electroless etching of n-type Si (111) substrates. The FESEM images demonstrate the formation of nano-porous surfaces that provide effective path for the incoming light to get trapped into the cavity of nanowires. The length of NWs increases from ∼1 to 10 μm with increase in the etching time having a diameter in the range of ∼25-82 nm. A transformation from zero to first order kinetics after a prolonged etching has been determined. The synthesized SiNWAs show high light trapping properties, including a maximum photon absorption across the entire visible and near IR range below the band gap of Si. The SiNWAs etched for 15 min exhibit extremely low specular and total reflectance of ∼0.2% and 4.5%, respectively over a broadband of wavelength. The reduction in the reflection loss is accompanied with the gradient of refractive index from air to Si substrate as well as due to the sub-wavelength structures, which manifests the light scattering effect. The COMSOL multiphysics simulation has been performed to study the high broadband light absorption capability in terms of the strong localized light field confinement by varying the length of the nanowire. Moreover, the SiNWs induces the dewetting ability at the solid/liquid interface and enhances the superhydrophobicity. Furthermore, a maximum length scale of 100-200 nm manifests a strong heterogeneity along the planar section of the surface of SiNWs. The study thus provides an insight on the light propagation into the random fractal geometries of Si nanowires. These outstanding properties should contribute to the structural optimization of various optoelectronic and photonic devices.

High brightness--multiple beamlets source for patterned X-ray production

DOEpatents

Leung, Ka-Ngo [Hercules, CA; Ji, Qing [Albany, CA; Barletta, William A [Oakland, CA; Jiang, Ximan [El Cerrito, CA; Ji, Lili [Albany, CA

2009-10-27

Techniques for controllably directing beamlets to a target substrate are disclosed. The beamlets may be either positive ions or electrons. It has been shown that beamlets may be produced with a diameter of 1 .mu.m, with inter-aperture spacings of 12 .mu.m. An array of such beamlets, may be used for maskless lithography. By step-wise movement of the beamlets relative to the target substrate, individual devices may be directly e-beam written. Ion beams may be directly written as well. Due to the high brightness of the beamlets from extraction from a multicusp source, exposure times for lithographic exposure are thought to be minimized. Alternatively, the beamlets may be electrons striking a high Z material for X-ray production, thereafter collimated to provide patterned X-ray exposures such as those used in CAT scans. Such a device may be used for remote detection of explosives.

Selective sintering of metal nanoparticle ink for maskless fabrication of an electrode micropattern using a spatially modulated laser beam by a digital micromirror device.

PubMed

An, Kunsik; Hong, Sukjoon; Han, Seungyong; Lee, Hyungman; Yeo, Junyeob; Ko, Seung Hwan

2014-02-26

We demonstrate selective laser sintering of silver (Ag) nanoparticle (NP) ink using a digital micromirror device (DMD) for the facile fabrication of 2D electrode pattern without any conventional lithographic means or scanning procedure. An arbitrary 2D pattern at the lateral size of 25 μm × 25 μm with 160 nm height is readily produced on a glass substrate by a short exposure of 532 nm Nd:YAG continuous wave laser. The resultant metal pattern exhibits low electrical resistivity of 10.8 uΩ · cm and also shows a fine edge sharpness by the virtue of low thermal conductivity of Ag NP ink. Furthermore, 10 × 10 star-shaped micropattern arrays are fabricated through a step-and-repeat scheme to ensure the potential of this process for the large-area metal pattern fabrication.

One-step Maskless Fabrication and Optical Characterization of Silicon Surfaces with Antireflective Properties and a White Color Appearance

PubMed Central

Schneider, Ling; Feidenhans’l, Nikolaj A.; Telecka, Agnieszka; Taboryski, Rafael J.

2016-01-01

We report a simple one-step maskless fabrication of inverted pyramids on silicon wafers by reactive ion etching. The fabricated surface structures exhibit excellent anti-reflective properties: The total reflectance of the nano inverted pyramids fabricated by our method can be as low as 12% without any anti-reflective layers, and down to only 0.33% with a silicon nitride coating. The results from angle resolved scattering measurements indicate that the existence of triple reflections is responsible for the reduced reflectance. The surfaces with the nano inverted pyramids also exhibit a distinct milky white color. PMID:27725703

Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

PubMed

Motrescu, Iuliana; Nagatsu, Masaaki

2016-05-18

With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

And There Was Light: Prospects for the Creation of Micro- and Nanostructures through Maskless Photolithography.

PubMed

Rühe, J

2017-09-26

In photolithographic processes, the light inducing the photochemical reactions is confined to a small volume, which enables direct writing of micro- and nanoscale features onto solid surfaces without the need of a predefined photomask. The direct writing process can be used to generate topographic patterns through photopolymerization or photo-cross-linking or can be employed to use light to generate chemical patterns on the surface with high spatial control, which would make such processes attractive for bioapplications. The prospects of maskless photolithography technologies with a focus on two-photon lithography and scanning-probe-based photochemical processes based on scanning near-field optical microscopy or beam pen lithography are discussed.

Development of new maskless manufacturing method for anti-reflection structure and application to large-area lens with curved surface

NASA Astrophysics Data System (ADS)

Yamamoto, Kazuya; Takaoka, Toshimitsu; Fukui, Hidetoshi; Haruta, Yasuyuki; Yamashita, Tomoya; Kitagawa, Seiichiro

2016-03-01

In general, thin-film coating process is widely applied on optical lens surface as anti-reflection function. In normal production process, at first lens is manufactured by molding, then anti-reflection is added by thin-film coating. In recent years, instead of thin-film coating, sub-wavelength structures adding on surface of molding die are widely studied and development to keep anti-reflection performance. As merits, applying sub-wavelength structure, coating process becomes unnecessary and it is possible to reduce man-hour costs. In addition to cost merit, these are some technical advantages on this study. Adhesion of coating depends on material of plastic, and it is impossible to apply anti-reflection function on arbitrary surface. Sub-wavelength structure can solve both problems. Manufacturing method of anti-reflection structure can be divided into two types mainly. One method is with the resist patterning, and the other is mask-less method that does not require patterning. What we have developed is new mask-less method which is no need for resist patterning and possible to impart an anti-reflection structure to large area and curved lens surface, and can be expected to apply to various market segments. We report developed technique and characteristics of production lens.

Maskless micro/nanofabrication on GaAs surface by friction-induced selective etching

PubMed Central

2014-01-01

In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface. PMID:24495647

Nonvacuum, maskless fabrication of a flexible metal grid transparent conductor by low-temperature selective laser sintering of nanoparticle ink.

PubMed

Hong, Sukjoon; Yeo, Junyeob; Kim, Gunho; Kim, Dongkyu; Lee, Habeom; Kwon, Jinhyeong; Lee, Hyungman; Lee, Phillip; Ko, Seung Hwan

2013-06-25

We introduce a facile approach to fabricate a metallic grid transparent conductor on a flexible substrate using selective laser sintering of metal nanoparticle ink. The metallic grid transparent conductors with high transmittance (>85%) and low sheet resistance (30 Ω/sq) are readily produced on glass and polymer substrates at large scale without any vacuum or high-temperature environment. Being a maskless direct writing method, the shape and the parameters of the grid can be easily changed by CAD data. The resultant metallic grid also showed a superior stability in terms of adhesion and bending. This transparent conductor is further applied to the touch screen panel, and it is confirmed that the final device operates firmly under continuous mechanical stress.

A versatile diffractive maskless lithography for single-shot and serial microfabrication.

PubMed

Jenness, Nathan J; Hill, Ryan T; Hucknall, Angus; Chilkoti, Ashutosh; Clark, Robert L

2010-05-24

We demonstrate a diffractive maskless lithographic system that is capable of rapidly performing both serial and single-shot micropatterning. Utilizing the diffractive properties of phase holograms displayed on a spatial light modulator, arbitrary intensity distributions were produced to form two and three dimensional micropatterns/structures in a variety of substrates. A straightforward graphical user interface was implemented to allow users to load templates and change patterning modes within the span of a few minutes. A minimum resolution of approximately 700 nm is demonstrated for both patterning modes, which compares favorably to the 232 nm resolution limit predicted by the Rayleigh criterion. The presented method is rapid and adaptable, allowing for the parallel fabrication of microstructures in photoresist as well as the fabrication of protein microstructures that retain functional activity.

Demonstration of lithography patterns using reflective e-beam direct write

NASA Astrophysics Data System (ADS)

Freed, Regina; Sun, Jeff; Brodie, Alan; Petric, Paul; McCord, Mark; Ronse, Kurt; Haspeslagh, Luc; Vereecke, Bart

2011-04-01

Traditionally, e-beam direct write lithography has been too slow for most lithography applications. E-beam direct write lithography has been used for mask writing rather than wafer processing since the maximum blur requirements limit column beam current - which drives e-beam throughput. To print small features and a fine pitch with an e-beam tool requires a sacrifice in processing time unless one significantly increases the total number of beams on a single writing tool. Because of the uncertainty with regards to the optical lithography roadmap beyond the 22 nm technology node, the semiconductor equipment industry is in the process of designing and testing e-beam lithography tools with the potential for high volume wafer processing. For this work, we report on the development and current status of a new maskless, direct write e-beam lithography tool which has the potential for high volume lithography at and below the 22 nm technology node. A Reflective Electron Beam Lithography (REBL) tool is being developed for high throughput electron beam direct write maskless lithography. The system is targeting critical patterning steps at the 22 nm node and beyond at a capital cost equivalent to conventional lithography. Reflective Electron Beam Lithography incorporates a number of novel technologies to generate and expose lithographic patterns with a throughput and footprint comparable to current 193 nm immersion lithography systems. A patented, reflective electron optic or Digital Pattern Generator (DPG) enables the unique approach. The Digital Pattern Generator is a CMOS ASIC chip with an array of small, independently controllable lens elements (lenslets), which act as an array of electron mirrors. In this way, the REBL system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The lens elements on the DPG are fabricated at IMEC (Leuven, Belgium) under IMEC's CMORE program. The CMOS fabricated DPG contains ~ 1,000,000 lens elements, allowing for 1,000,000 individually controllable beamlets. A single lens element consists of 5 electrodes, each of which can be set at controlled voltage levels to either absorb or reflect the electron beam. A system using a linear movable stage and the DPG integrated into the electron optics module was used to expose patterns on device representative wafers. Results of these exposure tests are discussed.

Development of a poly(dimethylacrylamide) based matrix material for solid phase high density peptide array synthesis employing a laser based material transfer

NASA Astrophysics Data System (ADS)

Ridder, Barbara; Foertsch, Tobias C.; Welle, Alexander; Mattes, Daniela S.; von Bojnicic-Kninski, Clemens M.; Loeffler, Felix F.; Nesterov-Mueller, Alexander; Meier, Michael A. R.; Breitling, Frank

2016-12-01

Poly(dimethylacrylamide) (PDMA) based matrix materials were developed for laser-based in situ solid phase peptide synthesis to produce high density arrays. In this specific array synthesis approach, amino acid derivatives are embedded into a matrix material, serving as a ;solid; solvent material at room temperature. Then, a laser pulse transfers this mixture to the target position on a synthesis slide, where the peptide array is synthesized. Upon heating above the glass transition temperature of the matrix material, it softens, allowing diffusion of the amino acid derivatives to the synthesis surface and serving as a solvent for peptide bond formation. Here, we synthesized PDMA six-arm star polymers, offering the desired matrix material properties, using atom transfer radical polymerization. With the synthesized polymers as matrix material, we structured and synthesized arrays with combinatorial laser transfer. With densities of up to 20,000 peptide spots per cm2, the resolution could be increased compared to the commercially available standard matrix material. Time-of-Flight Secondary Ion Mass Spectrometry experiments revealed the penetration behavior of an amino acid derivative into the prepared acceptor synthesis surface and the effectiveness of the washing protocols.

Identification of transcribed sequences in Arabidopsis thaliana by using high-resolution genome tiling arrays

PubMed Central

Stolc, Viktor; Samanta, Manoj Pratim; Tongprasit, Waraporn; Sethi, Himanshu; Liang, Shoudan; Nelson, David C.; Hegeman, Adrian; Nelson, Clark; Rancour, David; Bednarek, Sebastian; Ulrich, Eldon L.; Zhao, Qin; Wrobel, Russell L.; Newman, Craig S.; Fox, Brian G.; Phillips, George N.; Markley, John L.; Sussman, Michael R.

2005-01-01

Using a maskless photolithography method, we produced DNA oligonucleotide microarrays with probe sequences tiled throughout the genome of the plant Arabidopsis thaliana. RNA expression was determined for the complete nuclear, mitochondrial, and chloroplast genomes by tiling 5 million 36-mer probes. These probes were hybridized to labeled mRNA isolated from liquid grown T87 cells, an undifferentiated Arabidopsis cell culture line. Transcripts were detected from at least 60% of the nearly 26,330 annotated genes, which included 151 predicted genes that were not identified previously by a similar genome-wide hybridization study on four different cell lines. In comparison with previously published results with 25-mer tiling arrays produced by chromium masking-based photolithography technique, 36-mer oligonucleotide probes were found to be more useful in identifying intron–exon boundaries. Using two-dimensional HPLC tandem mass spectrometry, a small-scale proteomic analysis was performed with the same cells. A large amount of strongly hybridizing RNA was found in regions “antisense” to known genes. Similarity of antisense activities between the 25-mer and 36-mer data sets suggests that it is a reproducible and inherent property of the experiments. Transcription activities were also detected for many of the intergenic regions and the small RNAs, including tRNA, small nuclear RNA, small nucleolar RNA, and microRNA. Expression of tRNAs correlates with genome-wide amino acid usage. PMID:15755812

Identification of transcribed sequences in Arabidopsis thaliana by using high-resolution genome tiling arrays

NASA Technical Reports Server (NTRS)

Stolc, Viktor; Samanta, Manoj Pratim; Tongprasit, Waraporn; Sethi, Himanshu; Liang, Shoudan; Nelson, David C.; Hegeman, Adrian; Nelson, Clark; Rancour, David; Bednarek, Sebastian;

Waveform synthesizer

DOEpatents

Franks, Larry A.; Nelson, Melvin A.

1981-01-01

A method of producing optical and electrical pulses of desired shape. An optical pulse of arbitrary but defined shape illuminates one end of an array of optical fiber waveguides of differing lengths to time differentiate the input pulse. The optical outputs at the other end of the array are combined to form a synthesized pulse of desired shape.

Method for Synthesizing Metal Nanowires in Anodic Alumina Membranes Using Solid State Reduction

NASA Technical Reports Server (NTRS)

Martinez-Inesta, Maria M (Inventor); Feliciano, Jennie (Inventor); Quinones-Fontalvo, Leonel (Inventor)

2016-01-01

The invention proposes a novel method for the fabrication of regular arrays of MNWs using solid-state reduction (SSR). Using this method copper (Cu), silver (Ag), and palladium (Pd) nanowire (NWs) arrays were synthesized using anodic alumina membranes (AAMs) as templates. Depending on the metal loading used the NWs reached different diameters.

Evolution and characteristics of GaN nanowires produced via maskless reactive ion etching.

PubMed

Haab, Anna; Mikulics, Martin; Sutter, Eli; Jin, Jiehong; Stoica, Toma; Kardynal, Beata; Rieger, Torsten; Grützmacher, Detlev; Hardtdegen, Hilde

2014-06-27

The formation of nanowires (NWs) by reactive ion etching (RIE) of maskless GaN layers was investigated. The morphological, structural and optical characteristics of the NWs were studied and compared to those of the layer they evolve from. It is shown that the NWs are the result of a defect selective etching process. The evolution of density and length with etching time is discussed. Densely packed NWs with a length of more than 1 μm and a diameter of ∼60 nm were obtained by RIE of a ∼2.5 μm thick GaN layer. The NWs are predominantly free of threading dislocations and show an improvement of optical properties compared to their layer counterpart. The production of NWs via a top down process on non-masked group III-nitride layers is assessed to be very promising for photovoltaic applications.

Mask-less patterning of organic light emitting diodes using electrospray and selective biasing on pixel electrodes

NASA Astrophysics Data System (ADS)

Lee, Sangyeob; Koo, Hyun; Cho, Sunghwan

2015-04-01

Wet process of soluble organic light emitting diode (OLED) materials has attracted much attention due to its potential as a large-area manufacturing process with high productivity. Electrospray (ES) deposition is one of candidates of organic thin film formation process for OLED. However, to fabricate red, green, and blue emitters for color display, a fine metal mask is required during spraying emitter materials. We demonstrate a mask-less color pixel patterning process using ES of soluble OLED materials and selective biasing on pixel electrodes and a spray nozzle. We show red and green line patterns of OLED materials. It was found that selective patterning can be allowed by coulomb repulsion between nozzle and pixel. Furthermore, we fabricated blue fluorescent OLED devices by vacuum evaporation and ES processes. The device performance of ES processed OLED showed nearly identical current-voltage characteristics and slightly lower current efficiency compared to vacuum processed OLED.

Mapper: high throughput maskless lithography

NASA Astrophysics Data System (ADS)

Kuiper, V.; Kampherbeek, B. J.; Wieland, M. J.; de Boer, G.; ten Berge, G. F.; Boers, J.; Jager, R.; van de Peut, T.; Peijster, J. J. M.; Slot, E.; Steenbrink, S. W. H. K.; Teepen, T. F.; van Veen, A. H. V.

2009-01-01

Maskless electron beam lithography, or electron beam direct write, has been around for a long time in the semiconductor industry and was pioneered from the mid-1960s onwards. This technique has been used for mask writing applications as well as device engineering and in some cases chip manufacturing. However because of its relatively low throughput compared to optical lithography, electron beam lithography has never been the mainstream lithography technology. To extend optical lithography double patterning, as a bridging technology, and EUV lithography are currently explored. Irrespective of the technical viability of both approaches, one thing seems clear. They will be expensive [1]. MAPPER Lithography is developing a maskless lithography technology based on massively-parallel electron-beam writing with high speed optical data transport for switching the electron beams. In this way optical columns can be made with a throughput of 10-20 wafers per hour. By clustering several of these columns together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives. In 2007 MAPPER obtained its Proof of Lithography milestone by exposing in its Demonstrator 45 nm half pitch structures with 110 electron beams in parallel, where all the beams where individually switched on and off [2]. In 2008 MAPPER has taken a next step in its development by building several tools. A new platform has been designed and built which contains a 300 mm wafer stage, a wafer handler and an electron beam column with 110 parallel electron beams. This manuscript describes the first patterning results with this 300 mm platform.

Tuning micropillar tapering for optimal friction performance of thermoplastic gecko-inspired adhesive.

PubMed

Kim, Yongkwan; Chung, Yunsie; Tsao, Angela; Maboudian, Roya

2014-05-14

We present a fabrication method and friction testing of a gecko-inspired thermoplastic micropillar array with control over the tapering angle of the pillar sidewall. A combination of deep reactive ion etching of vertical silicon pillars and subsequent maskless chemical etching produces templates with various widths and degrees of taper, which are then replicated with low-density polyethylene. As the silicon pillars on the template are chemically etched in a bath consisting of hydrofluoric acid, nitric acid, and acetic acid (HNA), the pillars are progressively thinned, then shortened. The replicated polyethylene pillar arrays exhibit a corresponding increase in friction as the stiffness is reduced with thinning and then a decrease in friction as the stiffness is again increased. The dilution of the HNA bath in water influences the tapering angle of the silicon pillars. The friction of the replicated pillars is maximized for the taper angle that maximizes the contact area at the tip which in turn is influenced by the stiffness of the tapered pillars. To provide insights on how changes in microscale geometry and contact behavior may affect friction of the pillar array, the pillars are imaged by scanning electron microscopy after friction testing, and the observed deformation behavior from shearing is related to the magnitude of the macroscale friction values. It is shown that the tapering angle critically changes the pillar compliance and the available contact area. Simple finite element modeling calculations are performed to support that the observed deformation is consistent with what is expected from a mechanical analysis. We conclude that friction can be maximized via proper pillar tapering with low stiffness that still maintains enough contact area to ensure high adhesion.

High-throughput NGL electron-beam direct-write lithography system

NASA Astrophysics Data System (ADS)

Parker, N. William; Brodie, Alan D.; McCoy, John H.

2000-07-01

Electron beam lithography systems have historically had low throughput. The only practical solution to this limitation is an approach using many beams writing simultaneously. For single-column multi-beam systems, including projection optics (SCALPELR and PREVAIL) and blanked aperture arrays, throughput and resolution are limited by space-charge effects. Multibeam micro-column (one beam per column) systems are limited by the need for low voltage operation, electrical connection density and fabrication complexities. In this paper, we discuss a new multi-beam concept employing multiple columns each with multiple beams to generate a very large total number of parallel writing beams. This overcomes the limitations of space-charge interactions and low voltage operation. We also discuss a rationale leading to the optimum number of columns and beams per column. Using this approach we show how production throughputs >= 60 wafers per hour can be achieved at CDs

Optical synthesizer for a large quadrant-array CCD camera: Center director's discretionary fund

NASA Technical Reports Server (NTRS)

Hagyard, Mona J.

1992-01-01

The objective of this program was to design and develop an optical device, an optical synthesizer, that focuses four contiguous quadrants of a solar image on four spatially separated CCD arrays that are part of a unique CCD camera system. This camera and the optical synthesizer will be part of the new NASA-Marshall Experimental Vector Magnetograph, and instrument developed to measure the Sun's magnetic field as accurately as present technology allows. The tasks undertaken in the program are outlined and the final detailed optical design is presented.

Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Ximan

The shrinking of IC devices has followed the Moore's Law for over three decades, which states that the density of transistors on integrated circuits will double about every two years. This great achievement is obtained via continuous advance in lithography technology. With the adoption of complicated resolution enhancement technologies, such as the phase shifting mask (PSM), the optical proximity correction (OPC), optical lithography with wavelength of 193 nm has enabled 45 nm printing by immersion method. However, this achievement comes together with the skyrocketing cost of masks, which makes the production of low volume application-specific IC (ASIC) impractical. In ordermore » to provide an economical lithography approach for low to medium volume advanced IC fabrication, a maskless ion beam lithography method, called Maskless Micro-ion-beam Reduction Lithography (MMRL), has been developed in the Lawrence Berkeley National Laboratory. The development of the prototype MMRL system has been described by Dr. Vinh Van Ngo in his Ph.D. thesis. But the resolution realized on the prototype MMRL system was far from the design expectation. In order to improve the resolution of the MMRL system, the ion optical system has been investigated. By integrating a field-free limiting aperture into the optical column, reducing the electromagnetic interference and cleaning the RF plasma, the resolution has been improved to around 50 nm. Computational analysis indicates that the MMRL system can be operated with an exposure field size of 0.25 mm and a beam half angle of 1.0 mrad on the wafer plane. Ion-ion interactions have been studied with a two-particle physics model. The results are in excellent agreement with those published by the other research groups. The charge-interaction analysis of MMRL shows that the ion-ion interactions must be reduced in order to obtain a throughput higher than 10 wafers per hour on 300-mm wafers. In addition, two different maskless lithography strategies have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3δ CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator.« less

Maskless direct laser writing with visible light: Breaking through the optical resolving limit with cooperative manipulations of nonlinear reverse saturation absorption and thermal diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Jingsong, E-mail: weijingsong@siom.ac.cn; Wang, Rui; University of Chinese Academy of Sciences, Beijing 100049

In this work, the resolving limit of maskless direct laser writing is overcome by cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion, where the nonlinear reverse saturation absorption can induce the formation of below diffraction-limited energy absorption spot, and the thermal diffusion manipulation can make the heat quantity at the central region of energy absorption spot propagate along the thin film thickness direction. The temperature at the central region of energy absorption spot transiently reaches up to melting point and realizes nanolithography. The sample “glass substrate/AgInSbTe” is prepared, where AgInSbTe is taken as nonlinear reverse saturation absorption thinmore » film. The below diffraction-limited energy absorption spot is simulated theoretically and verified experimentally by near-field spot scanning method. The “glass substrate/Al/AgInSbTe” sample is prepared, where the Al is used as thermal conductive layer to manipulate the thermal diffusion channel because the thermal diffusivity coefficient of Al is much larger than that of AgInSbTe. The direct laser writing is conducted by a setup with a laser wavelength of 650 nm and a converging lens of NA=0.85, the lithographic marks with a size of about 100 nm are obtained, and the size is only about 1/10 the incident focused spot. The experimental results indicate that the cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion is a good method to realize nanolithography in maskless direct laser writing with visible light.« less

Experimental Study on Ultrasonic Computed Tomography Using Transducers Arrayed on the Internal Surface of a Cylinder

NASA Astrophysics Data System (ADS)

Kim, Jung-Soon; Kim, Moo-Joon; Kim, Jung-Ho; Ha, Kang-Lyeol

2005-06-01

In this study, ultrasonic array transducers with 32 vibrators arranged on the internal surface of a part of a cylinder were fabricated. The vibrators were operated by the piezoelectric transverse effect. By controlling the phase of the input signal for every vibrator, a quasi plane wave was synthesized. Using the fabricated array, inverse scattering ultrasonic computed tomography (UCT) was carried out with a phantom specimen after checking the plane wave generation. It was confirmed that the plane wave was synthesized successfully and a sound velocity image of the phantom was obtained by the plane wave. Consequently, it was noted that the array could be employed as a transmitter and receiver for data acquisition in UCT.

Controllable synthesis and optical properties of novel ZnO cone arrays via vapor transport at low temperature.

PubMed

Han, Xinhai; Wang, Guanzhong; Jie, Jiansheng; Choy, Wallace C H; Luo, Yi; Yuk, T I; Hou, J G

2005-02-24

Novel ZnO cone arrays with controllable morphologies have been synthesized on silicon (100) substrates by thermal evaporation of metal Zn powder at a low temperature of 570 degrees C without a metal catalyst. Clear structure evolutions were observed using scanning electron microscopy: well-aligned ZnO nanocones, double-cones with growing head cones attached by stem cones, and cones with straight hexagonal pillar were obtained as the distance between the source and the substrates was increased. X-ray diffraction shows that all cone arrays grow along the c-axis. Raman and photoluminescence spectra reveal that the optical properties of the buffer layer between the ZnO cone arrays and the silicon substrates are better than those of the ZnO cone arrays due to high concentration of Zn in the heads of the ZnO cone arrays and higher growth temperature of the buffer layer. The growth of ZnO arrays reveals that the cone arrays are synthesized through a self-catalyzed vapor-liquid-solid (VLS) process.

A rapid, maskless 3D prototyping for fabrication of capillary circuits: Toward urinary protein detection.

PubMed

Yan, Sheng; Zhu, Yuanqing; Tang, Shi-Yang; Li, Yuxing; Zhao, Qianbin; Yuan, Dan; Yun, Guolin; Zhang, Jun; Zhang, Shiwu; Li, Weihua

2018-04-01

Proteinuria is an established risk marker for progressive renal function loss and patients would significantly benefit from a point-of-care testing. Although extensive work has been done to develop the microfluidic devices for the detection of urinary protein, they need the complicated operation and bulky peripherals. Here, we present a rapid, maskless 3D prototyping for fabrication of capillary fluidic circuits using laser engraving. The capillary circuits can be fabricated in a short amount of time (<10 min) without the requirements of clean-room facilities and photomasks. The advanced capillary components (e.g., trigger valves, retention valves and retention bursting valves) were fabricated, enabling the sequential liquid delivery and sample-reagent mixing. With the integration of smartphone-based detection platform, the microfluidic device can quantify the urinary protein via a colorimetric analysis. By eliminating the bulky and expensive equipment, this smartphone-based detection platform is portable for on-site quantitative detection. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Directed Nanopatterning with Nonlinear Laser Lithography

NASA Astrophysics Data System (ADS)

Tokel, Onur; Yavuz, Ozgun; Ergecen, Emre; Pavlov, Ihor; Makey, Ghaith; Ilday, Fatih Omer

In spite of the successes of maskless optical nanopatterning methods, it remains extremely challenging to create any isotropic, periodic nanopattern. Further, available optical techniques lack the long-range coverage and high periodicity demanded by photonics and photovoltaics applications. Here, we provide a novel solution with Nonlinear Laser Lithography (NLL) approach. Notably, we demonstrate that self-organized nanopatterns can be produced in all possible Bravais lattice types. Further, we show that carefully chosen defects or structued noise can direct NLL symmetries. Exploitation of directed self-organizatio to select or guide to predetermined symmetries is a new capability. Predictive capabilities for such far-from-equilibrium, dissipative systems is very limited due to a lack of experimental systems with predictive models. Here we also present a completely predictive model, and experimentally confirm that the emergence of motifs can be regulated by engineering defects, while the polarization of the ultrafast laser prescribes lattice symmetry, which in turn reinforces translational invariance. Thus, NLL enables a novel, maskless nanofabrication approach, where laser-induced nanopatterns can be rapidly created in any lattice symmetry

Synthesis of multiple shaped beam antenna patterns

NASA Technical Reports Server (NTRS)

Stutzman, W. L.; Coffey, E. L.

1973-01-01

Results are presented of research into the problem of finding an excitation of a given antenna such that the desired radiation pattern is approximated to within acceptable limits. This is to be done in such a fashion that boundary conditions involving hardware limitations may be inserted into the problem. The intended application is synthesis of multiple shaped beam antennas. Since this is perhaps the most difficult synthesis problem an antenna engineer is likely to encounter, the approach taken was to include as a by-product capability for synthesizing simpler patterns. The synthesis technique has been almost totally computerized. The class of antennas which may be synthesized with the computer program are those which may be represented as planar (continuous or discrete) current distributions. The technique is not limited in this sense and could indeed by extended to include, for example, the synthesis of conformal arrays or current distributions on the surface of reflectors. The antenna types which the program is set up to synthesize are: line source, rectangular aperture, circular aperture, linear array, rectangular array, and arbitrary planar array.

Room temperature synthesis and optical properties of small diameter (5 nm) ZnO nanorod arrays.

PubMed

Cho, Seungho; Jang, Ji-Wook; Lee, Jae Sung; Lee, Kun-Hong

2010-10-01

We report a simple wet-chemical synthesis of ∼5 nm diameter ZnO nanorod arrays at room temperature (20 °C) and normal atmospheric pressure (1 atm) and their optical properties. They were single crystalline in nature, and grew in the [001] direction. These small diameter ZnO nanorod arrays can also be synthesized at 0 °C. Control experiments were also conducted. On the basis of the results, we propose a mechanism for the spontaneous growth of the small diameter ZnO structures. The optical properties of the 5 nm diameter ZnO nanorod arrays synthesized using this method were probed by UV-Visible diffuse reflectance spectroscopy. A clear blue-shift, relative to the absorption band from 50 nm diameter ZnO nanorod arrays, was attributed to the quantum confinement effects caused by the small nanocrystal size in the 5 nm diameter ZnO nanorods.

Optical Analysis of Power Distribution in Top-Emitting Organic Light Emitting Diodes Integrated with Nanolens Array Using Finite Difference Time Domain.

PubMed

Han, Kyung-Hoon; Park, Young-Sam; Cho, Doo-Hee; Han, Yoonjay; Lee, Jonghee; Yu, Byounggon; Cho, Nam Sung; Lee, Jeong-Ik; Kim, Jang-Joo

2018-06-06

Recently, we have addressed that a formation mechanism of a nanolens array (NLA) fabricated by using a maskless vacuum deposition is explained as the increase in surface tension of organic molecules induced by their crystallization. Here, as another research using finite difference time domain simulations, not electric field intensities but transmitted energies of electromagnetic waves inside and outside top-emitting blue organic light-emitting diodes (TOLEDs), without and with NLAs, are obtained, to easily grasp the effect of NLA formation on the light extraction of TOLEDs. Interestingly, the calculations show that NLA acts as an efficient light extraction structure. With NLA, larger transmitted energies in the direction from emitting layer to air are observed, indicating that NLAs send more light to air otherwise trapped in the devices by reducing the losses by waveguide and absorption. This is more significant for higher refractive index of NLA. Simulation and measurement results are consistent. A successful increase in both light extraction efficiency and color stability of blue TOLEDs, rarely reported before, is accomplished by introducing the highly process-compatible NLA technology using the one-step dry process. Blue TOLEDs integrated with a N, N'-di(1-naphthyl)- N, N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine NLA with a refractive index of 1.8 show a 1.55-times-higher light extraction efficiency, compared to those without it. In addition, viewing angle characteristics are enhanced and image blurring is reduced, indicating that the manufacturer-adaptable technology satisfies the requirements of highly efficient and color-stable top-emission displays.

Maskless laser writing of microscopic metallic interconnects

DOEpatents

Maya, Leon

1995-01-01

A method of forming a metal pattern on a substrate. The method includes depositing an insulative nitride film on a substrate and irradiating a laser beam onto the nitride film, thus decomposing the metal nitride into a metal constituent and a gaseous constituent, the metal constituent remaining in the nitride film as a conductive pattern.

Suppression of imaging crack caused by the gap between micromirrors in maskless lithography

NASA Astrophysics Data System (ADS)

Liang, Liwen; Zhou, Jinyun; Lei, Liang; Wang, Bo; Wang, Qu; Wen, Kunhua

2017-10-01

The digital micromirror device (DMD) is the key device in maskless lithography. However, because of the machinery manufacturing limit of DMDs, the gap between the micromirrors may destroy the continuity of the graphic. This work presents a simple way to fill the imaging crack by controlling the partial coherence factor σ of the light source. A crack can be regarded as the image of a dark space. By considering the resolving power for such cracks under partially coherent illumination, the images of such dark spaces can be covered, preventing them from being imaged on the substrate. By using mathematical derivations of the light intensity distribution exposed to the substrate, and by utilizing the diffraction effect induced by the finite aperture of the optical projection system, an appropriate σ value can be determined for eliminating the image of the crack in an actual scene. The numerical simulation results demonstrate that this method can ensure the continuity of the graphic at the critical partial coherence factor σc regardless of the shape of the target graphic.

Nanowall formation by maskless wet-etching on a femtosecond laser irradiated silicon surface

NASA Astrophysics Data System (ADS)

Lee, Siwoo; Jo, Kukhyun; Keum, Hee-sung; Chae, Sangmin; Kim, Yonghyeon; Choi, Jiyeon; Lee, Hyun Hwi; Kim, Hyo Jung

2018-04-01

We found that micro-cells surrounded by nanowalls can be formed by a maskless wet-etching process on Si (100) surfaces possessing Laser Induced Periodic Surface Structure (LIPSS) by femtosecond laser irradiation. The LIPSS process could produce periodic one-dimensional micron scale ripples on a Si surface, which could be developed into micro-cells by a subsequent etching process. The solution etching conditions strongly affected both the micro-cell and nanowall shapes such as the height and the thickness of nanowalls. The tetramethylammonium hydroxide solution created thin nanowalls and the resulting micro-cells with a well-flattened bottom while the KOH solution formed thick walls and incomplete micro-cells. The bottoms of micro-cells surrounded by the nanowalls were considerably flat with a 3.10 nm surface roughness. A pentacene layer was deposited on the micro-cells of a Si surface to evaluate the film properties by grazing incidence wide angle x-ray scattering measurements. The pentacene film on the micro-cell Si surface showed a strong film phase, which was comparable to the film phase grown on the atomically flat Si surface.

MAPPER: high-throughput maskless lithography

NASA Astrophysics Data System (ADS)

Wieland, M. J.; de Boer, G.; ten Berge, G. F.; Jager, R.; van de Peut, T.; Peijster, J. J. M.; Slot, E.; Steenbrink, S. W. H. K.; Teepen, T. F.; van Veen, A. H. V.; Kampherbeek, B. J.

2009-03-01

Maskless electron beam lithography, or electron beam direct write, has been around for a long time in the semiconductor industry and was pioneered from the mid-1960s onwards. This technique has been used for mask writing applications as well as device engineering and in some cases chip manufacturing. However because of its relatively low throughput compared to optical lithography, electron beam lithography has never been the mainstream lithography technology. To extend optical lithography double patterning, as a bridging technology, and EUV lithography are currently explored. Irrespective of the technical viability of both approaches, one thing seems clear. They will be expensive [1]. MAPPER Lithography is developing a maskless lithography technology based on massively-parallel electron-beam writing with high speed optical data transport for switching the electron beams. In this way optical columns can be made with a throughput of 10-20 wafers per hour. By clustering several of these columns together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives. In 2007 MAPPER obtained its Proof of Lithography milestone by exposing in its Demonstrator 45 nm half pitch structures with 110 electron beams in parallel, where all the beams where individually switched on and off [2]. In 2008 MAPPER has taken a next step in its development by building several tools. The objective of building these tools is to involve semiconductor companies to be able to verify tool performance in their own environment. To enable this, the tools will have a 300 mm wafer stage in addition to a 110-beam optics column. First exposures at 45 nm half pitch resolution have been performed and analyzed. On the same wafer it is observed that all beams print and based on analysis of 11 beams the CD for the different patterns is within 2.2 nm from target and the CD uniformity for the different patterns is better than 2.8 nm.

Towards frameless maskless SRS through real-time 6DoF robotic motion compensation.

PubMed

Belcher, Andrew H; Liu, Xinmin; Chmura, Steven; Yenice, Kamil; Wiersma, Rodney D

2017-11-13

Stereotactic radiosurgery (SRS) uses precise dose placement to treat conditions of the CNS. Frame-based SRS uses a metal head ring fixed to the patient's skull to provide high treatment accuracy, but patient comfort and clinical workflow may suffer. Frameless SRS, while potentially more convenient, may increase uncertainty of treatment accuracy and be physiologically confining to some patients. By incorporating highly precise robotics and advanced software algorithms into frameless treatments, we present a novel frameless and maskless SRS system where a robot provides real-time 6DoF head motion stabilization allowing positional accuracies to match or exceed those of traditional frame-based SRS. A 6DoF parallel kinematics robot was developed and integrated with a real-time infrared camera in a closed loop configuration. A novel compensation algorithm was developed based on an iterative closest-path correction approach. The robotic SRS system was tested on six volunteers, whose motion was monitored and compensated for in real-time over 15 min simulated treatments. The system's effectiveness in maintaining the target's 6DoF position within preset thresholds was determined by comparing volunteer head motion with and without compensation. Comparing corrected and uncorrected motion, the 6DoF robotic system showed an overall improvement factor of 21 in terms of maintaining target position within 0.5 mm and 0.5 degree thresholds. Although the system's effectiveness varied among the volunteers examined, for all volunteers tested the target position remained within the preset tolerances 99.0% of the time when robotic stabilization was used, compared to 4.7% without robotic stabilization. The pre-clinical robotic SRS compensation system was found to be effective at responding to sub-millimeter and sub-degree cranial motions for all volunteers examined. The system's success with volunteers has demonstrated its capability for implementation with frameless and maskless SRS treatments, potentially able to achieve the same or better treatment accuracies compared to traditional frame-based approaches.

Towards frameless maskless SRS through real-time 6DoF robotic motion compensation

NASA Astrophysics Data System (ADS)

Belcher, Andrew H.; Liu, Xinmin; Chmura, Steven; Yenice, Kamil; Wiersma, Rodney D.

2017-12-01

Stereotactic radiosurgery (SRS) uses precise dose placement to treat conditions of the CNS. Frame-based SRS uses a metal head ring fixed to the patient’s skull to provide high treatment accuracy, but patient comfort and clinical workflow may suffer. Frameless SRS, while potentially more convenient, may increase uncertainty of treatment accuracy and be physiologically confining to some patients. By incorporating highly precise robotics and advanced software algorithms into frameless treatments, we present a novel frameless and maskless SRS system where a robot provides real-time 6DoF head motion stabilization allowing positional accuracies to match or exceed those of traditional frame-based SRS. A 6DoF parallel kinematics robot was developed and integrated with a real-time infrared camera in a closed loop configuration. A novel compensation algorithm was developed based on an iterative closest-path correction approach. The robotic SRS system was tested on six volunteers, whose motion was monitored and compensated for in real-time over 15 min simulated treatments. The system’s effectiveness in maintaining the target’s 6DoF position within preset thresholds was determined by comparing volunteer head motion with and without compensation. Comparing corrected and uncorrected motion, the 6DoF robotic system showed an overall improvement factor of 21 in terms of maintaining target position within 0.5 mm and 0.5 degree thresholds. Although the system’s effectiveness varied among the volunteers examined, for all volunteers tested the target position remained within the preset tolerances 99.0% of the time when robotic stabilization was used, compared to 4.7% without robotic stabilization. The pre-clinical robotic SRS compensation system was found to be effective at responding to sub-millimeter and sub-degree cranial motions for all volunteers examined. The system’s success with volunteers has demonstrated its capability for implementation with frameless and maskless SRS treatments, potentially able to achieve the same or better treatment accuracies compared to traditional frame-based approaches.

Fabrication of Aligned Polyaniline Nanofiber Array via a Facile Wet Chemical Process.

PubMed

Sun, Qunhui; Bi, Wu; Fuller, Thomas F; Ding, Yong; Deng, Yulin

2009-06-17

In this work, we demonstrate for the first time a template free approach to synthesize aligned polyaniline nanofiber (PN) array on a passivated gold (Au) substrate via a facile wet chemical process. The Au surface was first modified using 4-aminothiophenol (4-ATP) to afford the surface functionality, followed subsequently by an oxidation polymerization of aniline (AN) monomer in an aqueous medium using ammonium persulfate as the oxidant and tartaric acid as the doping agent. The results show that a vertically aligned PANI nanofiber array with individual fiber diameters of ca. 100 nm, heights of ca. 600 nm and a packing density of ca. 40 pieces·µm(-2) , was synthesized. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A mask manufacturer's perspective on maskless lithography

NASA Astrophysics Data System (ADS)

Buck, Peter; Biechler, Charles; Kalk, Franklin

2005-11-01

Maskless Lithography (ML2) is again being considered for use in mainstream CMOS IC manufacturing. Sessions at technical conferences are being devoted to ML2. A multitude of new companies have been formed in the last several years to apply new concepts to breaking the throughput barrier that has in the past prevented ML2 from achieving the cost and cycle time performance necessary to become economically viable, except in rare cases. Has Maskless Lithography's (we used to call it "Direct Write Lithography") time really come? If so, what is the expected impact on the mask manufacturer and does it matter? The lithography tools used today in mask manufacturing are similar in concept to ML2 except for scale, both in throughput and feature size. These mask tools produce highly accurate lithographic images directly from electronic pattern files, perform multi-layer overlay, and mix-n-match across multiple tools, tool types and sites. Mask manufacturers are already accustomed to the ultimate low volume - one substrate per design layer. In order to achieve the economically required throughput, proposed ML2 systems eliminate or greatly reduce some of the functions that are the source of the mask writer's accuracy. Can these ML2 systems meet the demanding lithographic requirements without these functions? ML2 may eliminate the reticle but many of the processes and procedures performed today by the mask manufacturer are still required. Examples include the increasingly complex mask data preparation step and the verification performed to ensure that the pattern on the reticle is accurately representing the design intent. The error sources that are fixed on a reticle are variable with time on an ML2 system. It has been proposed that if ML2 is successful it will become uneconomical to be in the mask business - that ML2, by taking the high profit masks will take all profitability out of mask manufacturing and thereby endanger the entire semiconductor industry. Others suggest that a successful ML2 system solves the mask cost issue and thereby reduces the need and attractiveness of ML2. Are these concerns valid? In this paper we will present a perspective on maskless lithography from the considerable "direct write" experience of a mask manufacturer. We will examine the various business models proposed for ML2 insertion as well as the key technical challenges to achieving simultaneously the throughput and the lithographic quality necessary to become economically viable. We will consider the question of the economic viability of the mask industry in a post-ML2 world and will propose possible models where the mask industry can meaningfully participate.

Organized one dimensional nanomaterials: From preparations to applications

NASA Astrophysics Data System (ADS)

Wen, Xiaogang

This thesis is mainly concerned with the development of organized one dimensional (1D) nanomaterials and their applications. We have synthesized Ag2S, Cu2S nanowires, Fe2O3 nanobelt and nanowire arrays and ZnO nanobelt arrays from corresponding metal substrate respectively via gas solid reaction methods under different growth conditions. The effect of various parameters including temperature, reaction time, composition of gas, surface pre-oxidation, size of source materials etc. on the growth of metal oxide/sulfide 1D nanostructure have been studied systemically. The size and morphology of these 1D nanomaterials could be rationally controlled by adjusting the growth conditions. A tip growth mechanism has been confirmed based our results. The properties including PL, Raman, field effect transistors, and field emission of these materials have been measured. Cu(OH)2 nanoribbons have been synthesized by a solution solid reaction method using Cu and Cu2S nanowires as precursors. Cu(OH) 2 nanoribbons can form well-aligned arrays on Cu substrate. Low temperature facilitate the formation of Cu(OH)2 nanoribbon arrays. Reaction conditions affect the morphology, crystal structure, even composition of the products much. CuO nanorod arrays of several nm in diameter could be synthesis in changed condition. Cu(OH)2 nanoribbon arrays are good sacrifice template for synthesizing other Cu-based 1D nanomaterials. It has been converted to CuO, Cu2O, Cu8S9, Cu etc. 1D nanostructure through different physical and chemical reaction process. Au/Cu2S core/sheath nanowires have been synthesized in solution phase via a simple template-induced redox deposition process, after removing the Cu2S template, Au nanotubes have been formed. The photoelectrochemistry (PEC) properties of it have been studied. Ag dendritic nanostructures have been prepared via solution reaction. We have revealed that the stem, branch, and sub-branch grow along <100>, <111> and <100> directions, respectively. Such a preferential growth pattern along <100> and <111> alternately lead to the formation of the Ag nanodendrites. In another development, we have synthesized unltrathin Zn nanowires (<5nm) by a vapor transport method. Small molecules are induced into the gas phase as capping reagents. In this process, the small molecules serve as capping reagents or templates to confine the lateral growth and facilitate the formation of ultrathin 1D nanostructures. (Abstract shortened by UMI.)

Maskless laser writing of microscopic metallic interconnects

DOEpatents

Maya, L.

1995-10-17

A method of forming a metal pattern on a substrate is disclosed. The method includes depositing an insulative nitride film on a substrate and irradiating a laser beam onto the nitride film, thus decomposing the metal nitride into a metal constituent and a gaseous constituent, the metal constituent remaining in the nitride film as a conductive pattern. 4 figs.

Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study.

PubMed

Pimentel, Ana; Ferreira, Sofia Henriques; Nunes, Daniela; Calmeiro, Tomas; Martins, Rodrigo; Fortunato, Elvira

2016-04-20

The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C.

Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study

PubMed Central

Pimentel, Ana; Ferreira, Sofia Henriques; Nunes, Daniela; Calmeiro, Tomas; Martins, Rodrigo; Fortunato, Elvira

2016-01-01

The present work reports the influence of zinc oxide (ZnO) seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C. PMID:28773423

Conformal Robotic Stereolithography

PubMed Central

Stevens, Adam G.; Oliver, C. Ryan; Kirchmeyer, Matthieu; Wu, Jieyuan; Chin, Lillian; Polsen, Erik S.; Archer, Chad; Boyle, Casey; Garber, Jenna

2016-01-01

Abstract Additive manufacturing by layerwise photopolymerization, commonly called stereolithography (SLA), is attractive due to its high resolution and diversity of materials chemistry. However, traditional SLA methods are restricted to planar substrates and planar layers that are perpendicular to a single-axis build direction. Here, we present a robotic system that is capable of maskless layerwise photopolymerization on curved surfaces, enabling production of large-area conformal patterns and the construction of conformal freeform objects. The system comprises an industrial six-axis robot and a custom-built maskless projector end effector. Use of the system involves creating a mesh representation of the freeform substrate, generation of a triangulated toolpath with curved layers that represents the target object to be printed, precision mounting of the substrate in the robot workspace, and robotic photopatterning of the target object by coordinated motion of the robot and substrate. We demonstrate printing of conformal photopatterns on spheres of various sizes, and construction of miniature three-dimensional objects on spheres without requiring support features. Improvement of the motion accuracy and development of freeform toolpaths would enable construction of polymer objects that surpass the size and support structure constraints imparted by traditional SLA systems. PMID:29577062

Maskless and low-destructive nanofabrication on quartz by friction-induced selective etching

PubMed Central

2013-01-01

A low-destructive friction-induced nanofabrication method is proposed to produce three-dimensional nanostructures on a quartz surface. Without any template, nanofabrication can be achieved by low-destructive scanning on a target area and post-etching in a KOH solution. Various nanostructures, such as slopes, hierarchical stages and chessboard-like patterns, can be fabricated on the quartz surface. Although the rise of etching temperature can improve fabrication efficiency, fabrication depth is dependent only upon contact pressure and scanning cycles. With the increase of contact pressure during scanning, selective etching thickness of the scanned area increases from 0 to 2.9 nm before the yield of the quartz surface and then tends to stabilise after the appearance of a wear. Refabrication on existing nanostructures can be realised to produce deeper structures on the quartz surface. Based on Arrhenius fitting of the etching rate and transmission electron microscopy characterization of the nanostructure, fabrication mechanism could be attributed to the selective etching of the friction-induced amorphous layer on the quartz surface. As a maskless and low-destructive technique, the proposed friction-induced method will open up new possibilities for further nanofabrication. PMID:23531381

Controlled assembly of high-order nanoarray metal structures on bulk copper surface by femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Qin, Wanwan; Yang, Jianjun

2017-07-01

We report a new one-step maskless method to fabricate high-order nanoarray metal structures comprising periodic grooves and particle chains on a single-crystal Cu surface using femtosecond laser pulses at the central wavelength of 400 nm. Remarkably, when a circularly polarized infrared femtosecond laser pulse (spectrally centered at 800 nm) pre-irradiates the sample surface, the geometric dimensions of the composite structure can be well controlled. With increasing the energy fluence of the infrared laser pulse, both the groove width and particle diameter are observed to reduce, while the measured spacing-to-diameter ratio of the nanoparticles tends to present an increasing tendency. A physical scenario is proposed to elucidate the underlying mechanisms: as the infrared femtosecond laser pulse pre-irradiates the target, the copper surface is triggered to display anomalous transient physical properties, on which the subsequently incident Gaussian blue laser pulse is spatially modulated into fringe-like energy depositions via the excitation of ultrafast surface plasmon. During the following relaxation processes, the periodically heated thin-layer regions can be transferred into the metastable liquid rivulets and then they break up into nanodroplet arrays owing to the modified Rayleigh-like instability. This investigation indicates a simple integrated approach for active designing and large-scale assembly of complexed functional nanostructures on bulk materials.

MnO 2 nanotube and nanowire arrays by electrochemical deposition for supercapacitors

NASA Astrophysics Data System (ADS)

Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li

Highly ordered MnO 2 nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO 2 nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO 2 nanotube array electrode has superior capacitive behaviour to that of the MnO 2 nanowire array electrode. In addition to high specific capacitance, the MnO 2 nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors.

Nucleic acid arrays and methods of synthesis

DOEpatents

Sabanayagam, Chandran R.; Sano, Takeshi; Misasi, John; Hatch, Anson; Cantor, Charles

2001-01-01

The present invention generally relates to high density nucleic acid arrays and methods of synthesizing nucleic acid sequences on a solid surface. Specifically, the present invention contemplates the use of stabilized nucleic acid primer sequences immobilized on solid surfaces, and circular nucleic acid sequence templates combined with the use of isothermal rolling circle amplification to thereby increase nucleic acid sequence concentrations in a sample or on an array of nucleic acid sequences.

Solvothermal transformation of a calcium oleate precursor into large-sized highly ordered arrays of ultralong hydroxyapatite microtubes.

PubMed

Lu, Bing-Qiang; Zhu, Ying-Jie; Chen, Feng; Qi, Chao; Zhao, Xin-Yu; Zhao, Jing

2014-06-02

Hydroxyapatite (HAP), a well-known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge. In this work, inspired by the ordered structure of tooth enamel, we have successfully synthesized three-dimensional bulk materials with large sizes (millimeter scale) that are made of highly ordered arrays of ultralong HAP microtubes (HOAUHMs) by solvothermal transformation of calcium oleate precursor. The core-shell-structured oblate sphere consists of a core that is composed of HAP nanorods and a shell that consists of highly ordered HAP microtube arrays. The prepared HOAUHMs are large: 6.0 mm in diameter and up to 1.4 mm in thickness. With increasing solvothermal reaction time, the HOAUHMs grow larger; the microtubes become more uniform and more ordered. This work provides a new synthetic method for synthesizing highly ordered arrays of uniform HAP ultralong microtubes that are promising for biomedical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrated residential photovoltaic array development

NASA Astrophysics Data System (ADS)

Shepard, N. F., Jr.

1981-12-01

An advanced, universally-mountable, integrated residential photovoltaic array concept was defined based upon an in-depth formulation and evaluation of three candidate approaches which were synthesized from existing or proposed residential array concepts. The impact of module circuitry and process sequence is considered and technology gaps and performance drivers associated with residential photovoltaic array concepts are identified. The actual learning experience gained from the comparison of the problem areas of the hexagonal shingle design with the rectangular module design led to what is considered an advanced array concept. Building the laboratory mockup provided actual experience and the opportunity to uncover additional technology gaps.

Integrated residential photovoltaic array development

NASA Technical Reports Server (NTRS)

Shepard, N. F., Jr.

1981-01-01

An advanced, universally-mountable, integrated residential photovoltaic array concept was defined based upon an in-depth formulation and evaluation of three candidate approaches which were synthesized from existing or proposed residential array concepts. The impact of module circuitry and process sequence is considered and technology gaps and performance drivers associated with residential photovoltaic array concepts are identified. The actual learning experience gained from the comparison of the problem areas of the hexagonal shingle design with the rectangular module design led to what is considered an advanced array concept. Building the laboratory mockup provided actual experience and the opportunity to uncover additional technology gaps.

Transfer of vertically aligned carbon nanofibers to polydimethylsiloxane (PDMS) while maintaining their alignment and impalefection functionality.

PubMed

Pearce, Ryan C; Railsback, Justin G; Anderson, Bryan D; Sarac, Mehmet F; McKnight, Timothy E; Tracy, Joseph B; Melechko, Anatoli V

2013-02-01

Vertically aligned carbon nanofibers (VACNFs) are synthesized on Al 3003 alloy substrates by direct current plasma-enhanced chemical vapor deposition. Chemically synthesized Ni nanoparticles were used as the catalyst for growth. The Si-containing coating (SiN(x)) typically created when VACNFs are grown on silicon was produced by adding Si microparticles prior to growth. The fiber arrays were transferred to PDMS by spin coating a layer on the grown substrates, curing the PDMS, and etching away the Al in KOH. The fiber arrays contain many fibers over 15 μm (long enough to protrude from the PDMS film and penetrate cell membranes) and SiN(x) coatings as observed by SEM, EDX, and fluorescence microscopy. The free-standing array in PDMS was loaded with pVENUS-C1 plasmid and human brain microcapillary endothelial (HBMEC) cells and was successfully impalefected.

Integrated residential photovoltaic array development

NASA Technical Reports Server (NTRS)

Shepard, N. F., Jr.

1981-01-01

Three basic module design concepts were analyzed with respect to both production and installation costs. The results of this evaluation were used to synthesize a fourth design which incorporates the best features of these initial concepts to produce a module/array design approach which offers the promise of a substantial reduction in the installed cost of a residential array. A unique waterproofing and mounting scheme was used to reduce the cost of installing an integral array while still maintaining a high probability that the installed array will be watertight for the design lifetime of the system. This recommended concept will also permit the array to be mounted as a direct or stand-off installation with no changes to the module design.

Synthesis and characterization of beta-Ga2O3 nanorod array clumps by chemical vapor deposition.

PubMed

Shi, Feng; Wei, Xiaofeng

2012-11-01

beta-Ga2O3 nanorod array clumps were successfully synthesized on Si (111) substrates by chemical vapor deposition. The composition, microstructure, morphology, and light-emitting property of these clumps were characterized by X-ray diffraction, Fourier transform infrared spectrophotometry, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and photoluminescence. The results demonstrate that the sample synthesized at 1050 degrees C for 15 min was composed of monoclinic beta-Ga2O3 nanorod array clumps, where each single nanorod was about 300 nm in diameter with some nano-droplets on its tip. These results reveal that the growth mechanism agrees with the vapor-liquid-solid (VLS) process. The photoluminescence spectrum shows that the Ga2O3 nanorods have a blue emission at 438 nm, which may be attributed to defects, such as oxygen vacancies and gallium-oxygen vacancy pairs. Defect-energy aggregation confinement growth theory was proposed to explain the growth mechanism of Ga2O3 nanorod array clumps collaborated with the VLS mechanism.

The design and development of an automatic control system for the in-duct cancellation of spinning modes of sound. M.S. Thesis

NASA Technical Reports Server (NTRS)

Harrington, W. W.

1973-01-01

The reduction is discussed of the discrete tones generated by jet engines which is essential for jet aircraft to meet present and proposed noise standards. The discrete tones generated by the blades and vanes propagate in the inlet and exhaust duct in the form of spiraling acoustic waves, or spinning modes. The reduction of these spinning modes by the cancellation effect of the combination of two acoustic fields was investigated. The spinning mode synthesizer provided the means for effective study of this noise reduction scheme. Two sets of electrical-acoustical transducers located in an equally-spaced circular array simultaneously generate a specified spinning mode and the cancelling mode. Analysis of the wave equation for the synthesizer established the optimum cancelling array acoustic parameters for maximum sound pressure level reduction. The parameter dependence of the frequency ranges of propagation of single, specified circumferential modes generated by a single array, and of effective cancellation of the modes generated by two arrays, was determined. Substantial sound pressure level reduction was obtained for modes within these limits.

Maskless Nanoscale Writing of Nanoparticle-Polymer Composites and Nanoparticle Assemblies using Thermal Nanoprobes

DTIC Science & Technology

2009-09-14

the otherwise difficult to deposit Alq3 using a p(VDF-TrFE) carrier. The Alq3 retains its ability to fluoresce after deposition. (h) SEM of the...aluminum tris(8-hydroxyquinoline) ( Alq3 ) ∼0.9 P(VDF-TrFE) 1 zinc diethyldithiocarbamate ∼1.2 P(VDF-TrFE) 1 CdSe-ZnS core-shell 2-4 PE 1 dodecanethiol

Free-standing bimetallic nanorings and nanoring arrays made by on-wire lithography.

PubMed

Liusman, Cipto; Li, Shuzhou; Chen, Xiaodong; Wei, Wei; Zhang, Hua; Schatz, George C; Boey, Freddy; Mirkin, Chad A

2010-12-28

This paper describes a new strategy for synthesizing free-standing bimetallic nanorings and nanoring arrays based upon on-wire lithography and a galvanic replacement reaction. The strategy allows one to tune the diameter, length, and therefore aspect ratio of the nanorings. In addition, it can be used to produce arrays of nanorings in high yield with control over number and spacing. Spectroscopic studies and discrete dipole approximation calculations show that nanoring dimers exhibit greater surface enhanced Raman scattering than the analogous nanodisk dimers.

Next Generation Non-Vacuum, Maskless, Low Temperature Nanoparticle Ink Laser Digital Direct Metal Patterning for a Large Area Flexible Electronics

PubMed Central

Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P.; Ko, Seung Hwan

2012-01-01

Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition– and photolithography-based conventional metal patterning processes. The “digital” nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays. PMID:22900011

Next generation non-vacuum, maskless, low temperature nanoparticle ink laser digital direct metal patterning for a large area flexible electronics.

PubMed

Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P; Ko, Seung Hwan

2012-01-01

Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition- and photolithography-based conventional metal patterning processes. The "digital" nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays.

Mastering multi-depth bio-chip patterns with DVD LBRs

NASA Astrophysics Data System (ADS)

Carson, Doug

2017-08-01

Bio chip and bio disc are rapidly growing technologies used in medical, health and other industries. While there are numerous unique designs and features, these products all rely on precise three-dimensional micro-fluidic channels or arrays to move, separate and combine samples under test. These bio chip and bio disc consumables are typically manufactured by molding these parts to a precise three-dimensional pattern on a negative metal stamper, or they can be made in smaller quantities using an appropriate curable resin and a negative mold/stamper. Stampers required for bio chips have been traditionally made using either micro machining or XY stepping lithography. Both of these technologies have their advantages as well as limitations when it comes to creating micro-fluidic patterns. Significant breakthroughs in continuous maskless lithography have enabled accurate and efficient manufacturing of micro-fluidic masters using LBRs (Laser Beam Recorders) and DRIE (Deep Reactive Ion Etching). The important advantages of LBR continuous lithography vs. XY stepping lithography and micro machining are speed and cost. LBR based continuous lithography is >100x faster than XY stepping lithography and more accurate than micro machining. Several innovations were required in order to create multi-depth patterns with sub micron accuracy. By combining proven industrial LBRs with DCA's G3-VIA pattern generator and DRIE, three-dimensional bio chip masters and stampers are being manufactured efficiently and accurately.

Innovative Technologies for Maskless Lithography and Non-Conventional Patterning

DTIC Science & Technology

2008-08-01

wave sources are used and quantitative data is produced on the local field intensities and scattered plane and plasmon wave amplitudes and phases...transistors”, Transducers 2007, Lyon, France, 3EH5.P, 2007. 9. D. Huang and V. Subramanian “Iodine-doped pentacene schottky diodes for high-frequency RFID...wave sources are used and quantitative data is produced on the local field intensities and scattered plane and plasmon wave amplitudes and phases

Co3O4 nanowire@NiO nanosheet arrays for high performance asymmetric supercapacitors.

PubMed

Xing, Lei; Dong, Yidi; Hu, Fang; Wu, Xiang; Umar, Ahmad

2018-04-24

Herein, we report a simple and facile sequential hydrothermal process for the synthesis of Co3O4 nanowire@NiO nanosheet arrays (CNAs). The as-synthesized CNAs were characterized in detail using various analytical techniques, which confirmed the high crystallinity, purity, and high-density growth of these nanomaterials. From an application point of view, the as-synthesized CNAs were directly used as supercapacitor electrodes, revealing a specific capacitance of up to 2018 mF cm-2 at a current density of 2 mA cm-2. Furthermore, a flexible asymmetric supercapacitor was fabricated using the as-synthesized CNAs as the anode and activated carbon as the cathode, which revealed a specific capacitance of 134.6 mF cm-2 at a current density of 2 mA cm-2. In addition, the supercapacitor showed excellent capacity retention of 73.5% after 10 000 cycles at a current density of 10 mA cm-2.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Railsback, Justin; Pearce, Ryan; Sarac, Mehmet

Vertically aligned carbon nanofibers (VACNFs) are synthesized on 3003 aluminum substrates by direct current plasma enhanced chemical vapor deposition. Chemically synthesized nickel nanoparticles were used as the catalyst for growth. The silicon containing coating (SiNx) typically produced when VACNFs are grown on silicon was produced by adding silicon microparticles prior to growth. The fiber array was transferred to PDMS by spin casting a layer on the grown substrates, curing the PDMS, and etching away the aluminum in KOH. Energy dispersive x-ray spectroscopy, scanning electron microscopy, and fluorescence microscopy data are provided. The free standing array in PDMS was then loadedmore » with pVENUS-C1 plasmid and human brain microcapillary endothelial cells (HCMECHBMEC)/d3 cells were successfully impalefected with the plasmid.« less

Self-Ordered Titanium Dioxide Nanotube Arrays: Anodic Synthesis and Their Photo/Electro-Catalytic Applications

PubMed Central

Smith, York R.; Ray, Rupashree S.; Carlson, Krista; Sarma, Biplab; Misra, Mano

2013-01-01

Metal oxide nanotubes have become a widely investigated material, more specifically, self-organized titania nanotube arrays synthesized by electrochemical anodization. As a highly investigated material with a wide gamut of applications, the majority of published literature focuses on the solar-based applications of this material. The scope of this review summarizes some of the recent advances made using metal oxide nanotube arrays formed via anodization in solar-based applications. A general methodology for theoretical modeling of titania surfaces in solar applications is also presented. PMID:28811415

Glyco-Immune Diagnostic Signatures and Therapeutic Targets of Mesothelioma

DTIC Science & Technology

2015-09-01

Mesothelioma; Glycan Array; Immunoprofiles; Robotic Arrayer 16. SECURITY CLASSIFICATION OF: U 17. LIMITATION OF ABSTRACT: UU 18. NUMBER OF PAGES 19 19a...PROJECT SUMMARY: General Comments: This project involved novel technology in which biochemically synthesized glycans were robotically printed on glass...include 386 glycans and the platform was known as the PGA-400. (Figure 1) A standard robotic technology for printing a large range of

REBL: design progress toward 16 nm half-pitch maskless projection electron beam lithography

NASA Astrophysics Data System (ADS)

McCord, Mark A.; Petric, Paul; Ummethala, Upendra; Carroll, Allen; Kojima, Shinichi; Grella, Luca; Shriyan, Sameet; Rettner, Charles T.; Bevis, Chris F.

2012-03-01

REBL (Reflective Electron Beam Lithography) is a novel concept for high speed maskless projection electron beam lithography. Originally targeting 45 nm HP (half pitch) under a DARPA funded contract, we are now working on optimizing the optics and architecture for the commercial silicon integrated circuit fabrication market at the equivalent of 16 nm HP. The shift to smaller features requires innovation in most major subsystems of the tool, including optics, stage, and metrology. We also require better simulation and understanding of the exposure process. In order to meet blur requirements for 16 nm lithography, we are both shrinking the pixel size and reducing the beam current. Throughput will be maintained by increasing the number of columns as well as other design optimizations. In consequence, the maximum stage speed required to meet wafer throughput targets at 16 nm will be much less than originally planned for at 45 nm. As a result, we are changing the stage architecture from a rotary design to a linear design that can still meet the throughput requirements but with more conventional technology that entails less technical risk. The linear concept also allows for simplifications in the datapath, primarily from being able to reuse pattern data across dies and columns. Finally, we are now able to demonstrate working dynamic pattern generator (DPG) chips, CMOS chips with microfabricated lenslets on top to prevent crosstalk between pixels.

Exposure strategy and crystallization of Ge-Sb-Te thin film by maskless phase-change lithography

NASA Astrophysics Data System (ADS)

Ni, Ri Wen; Zeng, Bi Jian; Huang, Jun Zhu; Luo, Teng; Li, Zhen; Miao, Xiang Shui

2015-04-01

Maskless phase-change lithographic technology is developed as a photoresist of phase-change materials. The controllable growth behavior of the crystallization region on an amorphous thin film of Ge2Sb2Te5 (GST) irradiated by a laser beam is investigated; the GST thin film is deposited on a silicon substrate by the sputtering method. The results of a series of the experiments and the simulations all show that the width of a crystalline pattern is not only closely related to laser power and pulse duration, but also is apparently affected by the interactive area between the focused laser spot and thin film. The width maintains a nonlinear growth with the enhancement of the laser power until the thin film approaches melting, whereas it gradually reaches a constant value due to the local thermal equilibrium. This equilibrium makes the width irrelevant to the moving velocity with certain constraints when the laser works in continuous-wave mode. Within a defocus range of 15 μm, the widths of the crystalline patterns are obtained in a broad range from 690 nm to 8.13 μm under a 0.4-NA objective lens. By adjusting the defocus amount, some crystalline square patterns with expected widths in a wide range are fabricated, and the mean percentage error between the expected and fabricated widths is only 1.495%.

A novel design for maskless direct laser writing nanolithography: Combination of diffractive optical element and nonlinear absorption inorganic resists

NASA Astrophysics Data System (ADS)

Zha, Yikun; Wei, Jingsong; Gan, Fuxi

2013-09-01

Maskless laser direct writing lithography has been applied in the fabrication of optical elements and electric-optical devices. With the development of technology, the feature size of the elements and devices is required to reduce down to nanoscale. Increasing the numerical aperture of converging lens and shortening the laser wavelength are good methods to obtain the small spot and reduce the feature size to nanoscale, while this will cause the reduction of the depth of focus. The reduction of depth of focus will lead to some difficulties in the focusing and tracking servo controlling during the high speed laser direct writing lithography. In this work, the combination of the diffractive optical elements and the nonlinear absorption inorganic resist thin films cannot only extend the depth of focus, but also reduce the feature size of the lithographic marks down to nanoscale. By using the five-zone annular phase-only binary pupil filter as the diffractive optical elements and AgInSbTe as the nonlinear absorption inorganic resist thin film, the depth of focus cannot only extend to 7.39 times that of the focused spot, but also reduce the lithographic feature size down to 54.6 nm. The ill-effect of sidelobe on the lithography is also eliminated by the nonlinear reverse saturable absorption and the phase change threshold lithographic characteristics.

Light-emitting silicon nanowires obtained by metal-assisted chemical etching

NASA Astrophysics Data System (ADS)

Irrera, Alessia; Josè Lo Faro, Maria; D'Andrea, Cristiano; Alessio Leonardi, Antonio; Artoni, Pietro; Fazio, Barbara; Picca, Rosaria Anna; Cioffi, Nicola; Trusso, Sebastiano; Franzò, Giorgia; Musumeci, Paolo; Priolo, Francesco; Iacona, Fabio

2017-04-01

This review reports on a new process for the synthesis of Si nanowires (NWs), based on the wet etching of Si substrates assisted by a thin metal film. The approach exploits the thickness-dependent morphology of the metal layers to define uncovered nanometric Si regions, which behave as precursor sites for the formation of very dense (up to 1 × 1012 NW cm-2) arrays of long (up to several μm) and ultrathin (diameter of 5-9 nm) NWs. Intense photoluminescence (PL) peaks, characterized by maxima in the 640-750 nm range and by an external quantum efficiency of 0.5%, are observed when the Si NWs are excited at room temperature. The spectra show a blueshift if the size of the NW is decreased, in agreement with the occurrence of quantum confinement effects. The same etching process can be used to obtain ultrathin Si/Ge NWs from a Si/Ge multi-quantum well. The Si/Ge NWs exhibit—in addition to the Si-related PL peak—a signal at about 1240 nm due to Ge nanostructures. The huge surface area of the Si NW arrays can be exploited for sensing and analytical applications. The dependence of the PL intensity on the chemical composition of the surface indeed suggests interesting perspectives for the detection of gaseous molecules. Moreover, Si NWs decorated with Ag nanoparticles can be effectively employed in the interference-free laser desorption-ionization mass spectrometry of low-molecular-weight analytes. A device based on conductive Si NWs, showing intense and stable electroluminescence at an excitation voltage as low as 2 V, is also presented. The unique features of the proposed synthesis (the process is cheap, fast, maskless and compatible with Si technology) and the unusual optical properties of the material open the route towards new and unexpected perspectives for semiconductor NWs in photonics.

Photocatalytic degradation effect of malachite green and catalytic hydrogenation by UV-illuminated CeO2/CdO multilayered nanoplatelet arrays: Investigation of antifungal and antimicrobial activities.

PubMed

Maria Magdalane, C; Kaviyarasu, K; Judith Vijaya, J; Jayakumar, C; Maaza, M; Jeyaraj, B

2017-04-01

CeO 2 /CdO multi-layered nanoplatelet arrays have been synthesized by sol-gel method at two different temperatures using Citrus limonum fruit extract and the effect of particle size on the photocatalytic performance is studied. The particle size and phases was analysed by X-ray diffraction pattern (XRD) which brought out the formation of cubic phase in the synthesized samples. Field Emission Scanning electron microscopy (FESEM) revealed the surface morphology and made up of cumulative form of platelet shaped arrays with an average size of 10nm. The elemental composition and the purity of the nanomaterials were confirmed by Energy Dispersive X-ray spectroscopy (EDX). CeO 2 /CdO multilayered binary metal oxide nanoplatelet arrays were formed which was further explored with Fourier transform infrared spectroscopy (FTIR), it reveals that the nanocomposites contain CeO and CdO bonds. Determination of the direct and indirect bandgap energy of the nanoplatelet arrays was carried out by UV-Vis-DRS studies. In MG degradation, both the hole (h + ) and hydroxyl radical (OH) played a major role than the superoxide radical (O 2 - ). Possible photo degradation mechanisms are proposed and discussed in this article. CeO 2 /CdO multi-layered nanoplatelet arrays showed antibacterial activity and among the tested ones, it showed better growth inhibition towards P. aeruginosa MTCC73. Thus, this greener synthetic procedure was a highly effective method due to low-cost, highly effective UV light responsive material for environmental safety. Copyright © 2017. Published by Elsevier B.V.

Electrical and optical properties of binary CNx nanocone arrays synthesized by plasma-assisted reaction deposition.

PubMed

Liu, Xujun; Guan, Leilei; Fu, Xiaoniu; Zhao, Yu; Wu, Jiada; Xu, Ning

2014-03-21

Light-absorbing and electrically conductive binary CNx nanocone (CNNC) arrays have been fabricated using a glow discharge plasma-assisted reaction deposition method. The intact CNNCs with amorphous structure and central nickel-filled pipelines could be vertically and neatly grown on nickel-covered substrates according to the catalyst-leading mode. The morphologies and composition of the as-grown CNNC arrays can be well controlled by regulating the methane/nitrogen mixture inlet ratio, and their optical absorption and resistivity strongly depend on their morphologies and composition. Beside large specific surface area, the as-grown CNNC arrays demonstrate high wideband absorption, good conduction, and nice wettability to polymer absorbers.

Synthesis of ultrawideband radiation of combined antenna arrays excited by nanosecond bipolar voltage pulses

NASA Astrophysics Data System (ADS)

Koshelev, V. I.; Plisko, V. V.; Sevostyanov, E. A.

2017-05-01

To broaden the spectrum of high-power ultrawideband radiation, it is suggested to synthesize an electromagnetic pulse summing the pulses of different length in free space. On the example of model pulses corresponding to radiation of combined antennas excited by bipolar voltage pulses of the length of 2 and 3 ns, the possibility of twofold broadening of the radiation spectrum was demonstrated. Radiation pulses with the spectrum width exceeding three octaves were obtained. Pattern formation by the arrays of different geometry excited by the pulses having different time shifts was considered. Optimum array structure with the pattern maximum in the main direction was demonstrated on the example of a 2×2 array.

Ring-Opening Copolymerization of Epoxides and Cyclic Anhydrides with Discrete Metal Complexes: Structure-Property Relationships.

PubMed

Longo, Julie M; Sanford, Maria J; Coates, Geoffrey W

2016-12-28

Polyesters synthesized through the alternating copolymerization of epoxides and cyclic anhydrides compose a growing class of polymers that exhibit an impressive array of chemical and physical properties. Because they are synthesized through the chain-growth polymerization of two variable monomers, their syntheses can be controlled by discrete metal complexes, and the resulting materials vary widely in their functionality and physical properties. This polymer-focused review gives a perspective on the current state of the field of epoxide/anhydride copolymerization mediated by discrete catalysts and the relationships between the structures and properties of these polyesters.

Laser assisted deposition

NASA Technical Reports Server (NTRS)

Dutta, S.

1983-01-01

Applications of laser-based processing techniques to solar cell metallization are discussed. Laser-assisted thermal or photolytic maskless deposition from organometallic vapors or solutions may provide a viable alternative to photovoltaic metallization systems currently in use. High power, defocused excimer lasers may be used in conjunction with masks as an alternative to direct laser writing to provide higher throughput. Repeated pulsing with excimer lasers may eliminate the need for secondary plating techniques for metal film buildup. A comparison between the thermal and photochemical deposition processes is made.

Design and fabrication of multimode interference couplers based on digital micro-mirror system

NASA Astrophysics Data System (ADS)

Wu, Sumei; He, Xingdao; Shen, Chenbo

2008-03-01

Multimode interference (MMI) couplers, based on the self-imaging effect (SIE), are accepted popularly in integrated optics. According to the importance of MMI devices, in this paper, we present a novel method to design and fabricate MMI couplers. A technology of maskless lithography to make MMI couplers based on a smart digital micro-mirror device (DMD) system is proposed. A 1×4 MMI device is designed as an example, which shows the present method is efficient and cost-effective.

Characterization of photochromic computer-generated holograms for optical testing

NASA Astrophysics Data System (ADS)

Pariani, Giorgio; Bertarelli, Chiara; Bianco, Andrea; Schaal, Frederik; Pruss, Christof

2012-09-01

We investigate the possibility to produce photochromic CGHs with maskless lithography methods. For this purpose, optical properties and requirements of photochromic materials will be shown. A diarylethene-based polyurethane is developed and characterized. The resolution limit and the in uence of the writing parameters on the produced patterns, namely speed rate and light power, have been determined. After the optimization of the writing process, gratings and Fresnel Zone Plates are produced on the photochromic layer and diraction eciencies are measured. Improvements and perspectives will be discussed.

High performance hybrid silicon micropillar solar cell based on light trapping characteristics of Cu nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Yulong; Fan, Zhiqiang; Zhang, Weijia; Ma, Qiang; Jiang, Zhaoyi; Ma, Denghao

2018-05-01

High performance silicon combined structure (micropillar with Cu nanoparticles) solar cell has been synthesized from N-type silicon substrates based on the micropillar array. The combined structure solar cell exhibited higher short circuit current rather than the silicon miropillar solar cell, which the parameters of micropillar array are the same. Due to the Cu nanoparticles were decorated on the surface of silicon micropillar array, the photovoltaic properties of cells have been improved. In addition, the optimal efficiency of 11.5% was measured for the combined structure solar cell, which is better than the silicon micropillar cell.

Synthesis and high catalytic properties of mesoporous Pt nanowire array by novel conjunct template method

NASA Astrophysics Data System (ADS)

Zhong, Yi; Xu, Cai-Ling; Kong, Ling-Bin; Li, Hu-Lin

2008-12-01

A novel conjunct template method for fabricating mesoporous Pt nanowire array through direct current (DC) electrodeposition of Pt into the pores of anodic aluminum oxide (AAO) template on Ti/Si substrate from hexagonal structured lyotropic liquid crystalline phase is demonstrated in this paper. The morphology and structure of as-prepared Pt nanowire array are characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrocatalytic properties of Pt nanowire array for methanol are also investigated in detail. The results indicate that Pt nanowire array has the unique mesoporous structure of approximate 40-50 nm in diameter, which resulted in the high surface area and greatly improved electrocatalytic activity for methanol. The mesoporous Pt nanowire array synthesized by the new conjunct template method has a very promising application in portable fuel cell power sources.

Development and functional evaluation of biomimetic silicone surfaces with hierarchical micro/nano-topographical features demonstrates favourable in vitro foreign body response of breast-derived fibroblasts.

PubMed

Kyle, Daniel J T; Oikonomou, Antonios; Hill, Ernie; Bayat, Ardeshir

2015-06-01

Reproducing extracellular matrix topographical cues, such as those present within acellular dermal matrix (ADM), in synthetic implant surfaces, may augment cellular responses, independent of surface chemistry. This could lead to enhanced implant integration and performance while reducing complications. In this work, the hierarchical micro and nanoscale features of ADM were accurately and reproducibly replicated in polydimethylsiloxane (PDMS), using an innovative maskless 3D grayscale fabrication process not previously reported. Human breast derived fibroblasts (n=5) were cultured on PDMS surfaces and compared to commercially available smooth and textured silicone implant surfaces, for up to one week. Cell attachment, proliferation and cytotoxicity, in addition to immunofluorescence staining, SEM imaging, qRT-PCR and cytokine array were performed. ADM PDMS surfaces promoted cell adhesion, proliferation and survival (p=<0.05), in addition to increased focal contact formation and spread fibroblast morphology when compared to commercially available implant surfaces. PCNA, vinculin and collagen 1 were up-regulated in fibroblasts on biomimetic surfaces while IL8, TNFα, TGFβ1 and HSP60 were down-regulated (p=<0.05). A reduced inflammatory cytokine response was also observed (p=<0.05). This study represents a novel approach to the development of functionalised biomimetic prosthetic implant surfaces which were demonstrated to significantly attenuate the acute in vitro foreign body reaction to silicone. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Investigation on the Plasma-Induced Emission Properties of Large Area Carbon Nanotube Array Cathodes with Different Morphologies

PubMed Central

2011-01-01

Large area well-aligned carbon nanotube (CNT) arrays with different morphologies were synthesized by using a chemical vapor deposition. The plasma-induced emission properties of CNT array cathodes with different morphologies were investigated. The ratio of CNT height to CNT-to-CNT distance has considerable effects on their plasma-induced emission properties. As the ratio increases, emission currents of CNT array cathodes decrease due to screening effects. Under the pulse electric field of about 6 V/μm, high-intensity electron beams of 170–180 A/cm2 were emitted from the surface plasma. The production mechanism of the high-intensity electron beams emitted from the CNT arrays was plasma-induced emission. Moreover, the distribution of the electron beams was in situ characterized by the light emission from the surface plasma. PMID:27502662

Investigation on the Plasma-Induced Emission Properties of Large Area Carbon Nanotube Array Cathodes with Different Morphologies.

PubMed

Liao, Qingliang; Qin, Zi; Zhang, Zheng; Qi, Junjie; Zhang, Yue; Huang, Yunhua; Liu, Liang

2011-12-01

Large area well-aligned carbon nanotube (CNT) arrays with different morphologies were synthesized by using a chemical vapor deposition. The plasma-induced emission properties of CNT array cathodes with different morphologies were investigated. The ratio of CNT height to CNT-to-CNT distance has considerable effects on their plasma-induced emission properties. As the ratio increases, emission currents of CNT array cathodes decrease due to screening effects. Under the pulse electric field of about 6 V/μm, high-intensity electron beams of 170-180 A/cm(2) were emitted from the surface plasma. The production mechanism of the high-intensity electron beams emitted from the CNT arrays was plasma-induced emission. Moreover, the distribution of the electron beams was in situ characterized by the light emission from the surface plasma.

Substituent effects in double-helical hydrogen-bonded AAA-DDD complexes.

PubMed

Wang, Hong-Bo; Mudraboyina, Bhanu P; Wisner, James A

2012-01-27

Two series of DDD and AAA hydrogen-bond arrays were synthesized that form triply-hydrogen-bonded double-helical complexes when combined in CDCl(3) solution. Derivatization of the DDD arrays with electron-withdrawing groups increases the complex association constants by up to a factor of 30 in those arrays examined. Derivatization of the AAA arrays with electron donating substituents reveals a similar magnitude effect on the complex stabilities. The effect of substitution on both types of arrays are modeled quite satisfactorily (R(2) > 0.96 in all cases) as free energy relationships with respect to the sums of their Hammett substituent constants. In all, the complex stabilities can be manipulated over more than three orders of magnitude (>20 kJ mol(-1)) using this type of modification. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishiyama, Takeshi, E-mail: ishiyama@ee.tut.ac.jp; Nakane, Takaya, E-mail: ishiyama@ee.tut.ac.jp; Fujii, Tsutomu, E-mail: ishiyama@ee.tut.ac.jp

Arrays of single-crystal zinc oxide (ZnO) nanowires have been synthesized on silicon substrates by vapor-liquid-solid growth techniques. The effect of growth conditions including substrate temperature and Ar gas flow rate on growth properties of ZnO nanowire arrays were studied. Structural and optical characterization was performed using scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. SEM images of the ZnO nanowire arrays grown at various Ar gas flow rates indicated that the alignment and structural features of ZnO nanowires were affected by the gas flow rate. The PL of the ZnO nanowire arrays exhibited strong ultraviolet (UV) emission at 380 nmmore » and green emission around 510 nm. Moreover, the green emission reduced in Ga-doped sample.« less

Fabrication and Characterization of Vertically Aligned ZnO Nanorod Arrays via Inverted Monolayer Colloidal Crystals Mask

NASA Astrophysics Data System (ADS)

Chen, Cheng; Ding, Taotao; Qi, Zhiqiang; Zhang, Wei; Zhang, Jun; Xu, Juan; Chen, Jingwen; Dai, Jiangnan; Chen, Changqing

2018-04-01

The periodically ordered ZnO nanorod (NR) arrays have been successfully synthesized via a hydrothermal approach on the silicon substrates by templating of the TiO2 ring deriving from the polystyrene (PS) nanosphere monolayer colloidal crystals (MCC). With the inverted MCC mask, sol-gel-derived ZnO seeds could serve as the periodic nucleation positions for the site-specific growth of ZnO NRs. The large-scale patterned arrays of single ZnO NR with good side-orientation can be readily produced. According to the experimental results, the as-integrated ZnO NR arrays showed an excellent crystal quality and optical property, very suitable for optoelectronic applications such as stimulated emitters and ZnO photonic crystal devices.

Diffractive optical variable image devices generated by maskless interferometric lithography for optical security

NASA Astrophysics Data System (ADS)

Cabral, Alexandre; Rebordão, José M.

2011-05-01

In optical security (protection against forgery and counterfeit of products and documents) the problem is not exact reproduction but the production of something sufficiently similar to the original. Currently, Diffractive Optically Variable Image Devices (DOVID), that create dynamic chromatic effects which may be easily recognized but are difficult to reproduce, are often used to protect important products and documents. Well known examples of DOVID for security are 3D or 2D/3D holograms in identity documents and credit cards. Others are composed of shapes with different types of microstructures yielding by diffraction to chromatic dynamic effects. A maskless interferometric lithography technique to generate DOVIDs for optical security is presented and compared to traditional techniques. The approach can be considered as a self-masking focused holography on planes tilted with respect to the reference optical axes of the system, and is based on the Scheimpflug and Hinge rules. No physical masks are needed to ensure optimum exposure of the photosensitive film. The system built to demonstrate the technique relies on the digital mirrors device MOEMS technology from Texas Instruments' Digital Light Processing. The technique is linear on the number of specified colors and does not depend either on the area of the device or the number of pixels, factors that drive the complexity of dot-matrix based systems. The results confirmed the technique innovation and capabilities in the creation of diffractive optical elements for security against counterfeiting and forgery.

Porous nC-Si/SiOx nanostructured layer on Si substrate with tunable photoluminescent properties fabricated by direct, precursor-free microplasma irradiation in air

NASA Astrophysics Data System (ADS)

Wang, Tao; Hu, Mingshan; Yang, Bin; Wang, Xiaolin; Liu, Jingquan

2018-03-01

Porous nC-Si/SiOx photoluminescent nanostructured layer is fabricated by direct, precursor-free microplasma irradiation on Si substrate in air. It is confirmed that the deposited layer has porous and cluster-like structures by scanning electron microscopy (SEM) and profile scanning. Fourier transform infrared transmission (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) results indicate the produced layer is actually composed of nanocrystalline silicon (nC-Si) embedded in SiOx matrix. Transmission electron microscopy (TEM) and Raman results show the mean particle size of nC-Si is mainly between 2 and 4 nm and the highest crystalline volume fraction reaches 86.9%. The photoluminescence (PL) measurement of nC-Si/SiOx layer exhibited a broad band centered at 1.7-1.9 eV, ranging from 1.2-2.4 eV, and could be tuned by varying the applied voltage. The synthetical mechanisms are discussed to explain the PL properties of the layers. We propose that the energetic ions bombing induced by high compressed electric field near the Si surface is the main reason for porous nC-Si/SiOx formation. Maskless deposition of the line pattern of nC-Si/SiOx layer was also successfully fabricated. This simple, maskless, vacuum-free and precursor-free technique could be used in various potential optoelectronics and biological applications in the future.

Fabrication of heterogeneous nanomaterial array by programmable heating and chemical supply within microfluidic platform towards multiplexed gas sensing application

PubMed Central

Yang, Daejong; Kang, Kyungnam; Kim, Donghwan; Li, Zhiyong; Park, Inkyu

2015-01-01

A facile top-down/bottom-up hybrid nanofabrication process based on programmable temperature control and parallel chemical supply within microfluidic platform has been developed for the all liquid-phase synthesis of heterogeneous nanomaterial arrays. The synthesized materials and locations can be controlled by local heating with integrated microheaters and guided liquid chemical flow within microfluidic platform. As proofs-of-concept, we have demonstrated the synthesis of two types of nanomaterial arrays: (i) parallel array of TiO2 nanotubes, CuO nanospikes and ZnO nanowires, and (ii) parallel array of ZnO nanowire/CuO nanospike hybrid nanostructures, CuO nanospikes and ZnO nanowires. The laminar flow with negligible ionic diffusion between different precursor solutions as well as localized heating was verified by numerical calculation and experimental result of nanomaterial array synthesis. The devices made of heterogeneous nanomaterial array were utilized as a multiplexed sensor for toxic gases such as NO2 and CO. This method would be very useful for the facile fabrication of functional nanodevices based on highly integrated arrays of heterogeneous nanomaterials. PMID:25634814

5'to 3' nucleic acid synthesis using 3'-photoremovable protecting group

DOEpatents

Pirrung, Michael C.; Shuey, Steven W.; Bradley, Jean-Claude

1999-01-01

The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5' to 3' nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5' end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

Si-H induced synthesis of Si/Cu2O nanowire arrays for photoelectrochemical water splitting

NASA Astrophysics Data System (ADS)

Zhang, Shaoyang; She, Guangwei; Li, Shengyang; Mu, Lixuan; Shi, Wensheng

2018-01-01

We report a facile and low-cost method to synthesize Si/Cu2O heterojunction nanowire arrays, without SiOx, at the Si/Cu2O interface. The reductive Si-H bonds on the surface of Si nanowires plays a key role in situ by reducing Cu(II) ions to Cu2O nanocubes and avoiding the SiOx interface layer. Different pH values would vary the electrochemical potential of reactions and as a result, different products would be formed. Utilized as a photoanode for water splitting, Si/Cu2O nanowire arrays exhibit good photoelectrochemical performance.

Printing Peptide arrays with a complementary metal oxide semiconductor chip.

PubMed

Loeffler, Felix F; Cheng, Yun-Chien; Muenster, Bastian; Striffler, Jakob; Liu, Fanny C; Ralf Bischoff, F; Doersam, Edgar; Breitling, Frank; Nesterov-Mueller, Alexander

2013-01-01

: In this chapter, we discuss the state-of-the-art peptide array technologies, comparing the spot technique, lithographical methods, and microelectronic chip-based approaches. Based on this analysis, we describe a novel peptide array synthesis method with a microelectronic chip printer. By means of a complementary metal oxide semiconductor chip, charged bioparticles can be patterned on its surface. The bioparticles serve as vehicles to transfer molecule monomers to specific synthesis spots. Our chip offers 16,384 pixel electrodes on its surface with a spot-to-spot pitch of 100 μm. By switching the voltage of each pixel between 0 and 100 V separately, it is possible to generate arbitrary particle patterns for combinatorial molecule synthesis. Afterwards, the patterned chip surface serves as a printing head to transfer the particle pattern from its surface to a synthesis substrate. We conducted a series of proof-of-principle experiments to synthesize high-density peptide arrays. Our solid phase synthesis approach is based on the 9-fluorenylmethoxycarbonyl protection group strategy. After melting the particles, embedded monomers diffuse to the surface and participate in the coupling reaction to the surface. The method demonstrated herein can be easily extended to the synthesis of more complicated artificial molecules by using bioparticles with artificial molecular building blocks. The possibility of synthesizing artificial peptides was also shown in an experiment in which we patterned biotin particles in a high-density array format. These results open the road to the development of peptide-based functional modules for diverse applications in biotechnology.

LIPID BIOMARKER CHARACTERIZATION OF BLOOM-RELATED DINOFLAGELLATES

EPA Science Inventory

Marine eukaryotic algae synthesize an array of lipids of chemotaxonomic utility that are potentially valuable in characterizing phytoplankton communities. Sterols and photopigments characteristic of dinoflagellates are rarely found in other algal classes. Long chain (C28) highly ...

Synthesis and Characteristics of Large-Area and High-Filling CdS Nanowire Arrays in AAO Template.

PubMed

Lv, Xiao-Yi; Hou, Jun-Wei; Gao, Zhi-Xian; Liu, Hong-Fei

2018-05-01

CdS nanowires arrays were successfully synthesized by a simple solvothermal process using AAO as templates. The phase structures, morphologies, and optical properties of the products were investigated by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. It was found that the nanowires were composed of hexagonal structure CdS nanoparticles and the average diameters is about 60-70 nm. A strong green emission with a maximum around 505 nm was observed from the synthesized CdS nanowires at room temperature, which was attributed to near-band-edge emission. A 3D self-seed nucleation coalescent process was proposed for the formation of CdS nanowires structures. The present synthetic route is expected to be applied to the synthesis of other II-VI groups or other group's 1D semiconducting materials.

A General Method for the Chemical Synthesis of Large-Scale, Seamless Transition Metal Dichalcogenide Electronics.

PubMed

Li, Li; Guo, Yichuan; Sun, Yuping; Yang, Long; Qin, Liang; Guan, Shouliang; Wang, Jinfen; Qiu, Xiaohui; Li, Hongbian; Shang, Yuanyuan; Fang, Ying

2018-03-01

The capability to directly build atomically thin transition metal dichalcogenide (TMD) devices by chemical synthesis offers important opportunities to achieve large-scale electronics and optoelectronics with seamless interfaces. Here, a general approach for the chemical synthesis of a variety of TMD (e.g., MoS 2 , WS 2 , and MoSe 2 ) device arrays over large areas is reported. During chemical vapor deposition, semiconducting TMD channels and metallic TMD/carbon nanotube (CNT) hybrid electrodes are simultaneously formed on CNT-patterned substrate, and then coalesce into seamless devices. Chemically synthesized TMD devices exhibit attractive electrical and mechanical properties. It is demonstrated that chemically synthesized MoS 2 -MoS 2 /CNT devices have Ohmic contacts between MoS 2 /CNT hybrid electrodes and MoS 2 channels. In addition, MoS 2 -MoS 2 /CNT devices show greatly enhanced mechanical stability and photoresponsivity compared with conventional gold-contacted devices, which makes them suitable for flexible optoelectronics. Accordingly, a highly flexible pixel array based on chemically synthesized MoS 2 -MoS 2 /CNT photodetectors is applied for image sensing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plasmonic nanorod arrays of a two-segment dimer and a coaxial cable with 1 nm gap for large field confinement and enhancement

NASA Astrophysics Data System (ADS)

Cheng, Zi-Qiang; Nan, Fan; Yang, Da-Jie; Zhong, Yu-Ting; Ma, Liang; Hao, Zhong-Hua; Zhou, Li; Wang, Qu-Quan

2015-01-01

Seeking plasmonic nanostructures with large field confinement and enhancement is significant for photonic and electronic nanodevices with high sensitivity, reproducibility, and tunability. Here, we report the synthesis of plasmonic arrays composed of two-segment dimer nanorods and coaxial cable nanorods with ~1 nm gap insulated by a self-assembled Raman molecule monolayer. The gap-induced plasmon coupling generates an intense field in the gap region of the dimer junction and the cable interlayer. As a result, the longitudinal plasmon resonance of nanorod arrays with high tunability is obviously enhanced. Most interestingly, the field enhancement of dimer nanorod arrays can be tuned by the length ratio L1/L2 of the two segments, and the maximal enhancement appears at L1/L2 = 1. In that case, the two-photon luminescence (TPL) of dimer nanorod arrays and the Raman intensity in the dimer junction is enhanced by 27 and 30 times, respectively, under resonant excitation. In the same way, the Raman intensity in the gap region is enhanced 16 times for the coaxial cable nanorod arrays. The plasmonic nanorod arrays synthesized by the facile method, having tunable plasmon properties and large field enhancement, indicate an attractive pathway to the photonic nanodevices.Seeking plasmonic nanostructures with large field confinement and enhancement is significant for photonic and electronic nanodevices with high sensitivity, reproducibility, and tunability. Here, we report the synthesis of plasmonic arrays composed of two-segment dimer nanorods and coaxial cable nanorods with ~1 nm gap insulated by a self-assembled Raman molecule monolayer. The gap-induced plasmon coupling generates an intense field in the gap region of the dimer junction and the cable interlayer. As a result, the longitudinal plasmon resonance of nanorod arrays with high tunability is obviously enhanced. Most interestingly, the field enhancement of dimer nanorod arrays can be tuned by the length ratio L1/L2 of the two segments, and the maximal enhancement appears at L1/L2 = 1. In that case, the two-photon luminescence (TPL) of dimer nanorod arrays and the Raman intensity in the dimer junction is enhanced by 27 and 30 times, respectively, under resonant excitation. In the same way, the Raman intensity in the gap region is enhanced 16 times for the coaxial cable nanorod arrays. The plasmonic nanorod arrays synthesized by the facile method, having tunable plasmon properties and large field enhancement, indicate an attractive pathway to the photonic nanodevices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05544f

Chemical growth of ZnO nanorod arrays on textured nanoparticle nanoribbons and its second-harmonic generation performance

NASA Astrophysics Data System (ADS)

Gui, Zhou; Wang, Xian; Liu, Jian; Yan, Shanshan; Ding, Yanyan; Wang, Zhengzhou; Hu, Yuan

2006-07-01

On the basis of the highly oriented ZnO nanoparticle nanoribbons as the growth seed layer (GSL) and solution growth technique, we have synthesized vertical ZnO nanorod arrays with high density over a large area and multi-teeth brush nanostructure, respectively, according to the density degree of the arrangement of nanoparticle nanoribbons GSL on the glass substrate. This controllable and convenient technique opens the possibility of creating nanostructured film for industrial fabrication and may represent a facile way to get similar structures of other compounds by using highly oriented GSL to promote the vertical arrays growth. The growth mechanism of the formation of the ordered nanorod arrays is also discussed. The second-order nonlinear optical coefficient d31 of the vertical ZnO nanorod arrays measured by the Maker fringes technique is 11.3 times as large as that of d36 KH 2PO 4 (KDP).

Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Wei, Xing; Sugri Nbelayim, Pascal; Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2017-03-01

A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC-AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.

Enhanced photoemission from glancing angle deposited SiOx-TiO2 axial heterostructure nanowire arrays

NASA Astrophysics Data System (ADS)

Dhar, J. C.; Mondal, A.; Singh, N. K.; Chattopadhyay, K. K.

2013-05-01

The glancing angle deposition technique has been employed to synthesize SiOx-TiO2 heterostructure nanowire (NW) arrays on indium tin oxide (ITO) coated glass substrate. A field emission gun scanning electron microscopic image shows that the average diameter of the NWs is ˜50 nm. Transmission electron microscopy images show the formation of heterostructure NWs, which consist of ˜180 nm SiOx and ˜210 nm long TiO2. The selected-area electron diffraction shows the amorphous nature of the synthesized NWs, which was also confirmed by X-ray diffraction method. The main band absorption edges at 3.5 eV were found for both the SiOx-TiO2 and TiO2 NW arrays on ITO coated glass plate from optical absorption measurement. Ti3+ defect related sub-band gap transition at 2.5 eV was observed for TiO2 NWs, whereas heterostructure NWs revealed the SiOx optical band gap related transition at ˜2.2 eV. Two fold improved photon absorption as well as five times photoluminescence emission enhancement were observed for the SiOx-TiO2 multilayer NWs compared to TiO2 NWs.

Reconfigurable Microfluidic Magnetic Valve Arrays: Towards a Radiotherapy-Compatible Spheroid Culture Platform for the Combinatorial Screening of Cancer Therapies

PubMed Central

Labelle, Frédérique; Wong, Philip

2017-01-01

We introduce here a microfluidic cell culture platform or spheroid culture chamber array (SCCA) that can synthesize, culture, and enable fluorescence imaging of 3D cell aggregates (typically spheroids) directly on-chip while specifying the flow of reagents in each chamber via the use of an array of passive magnetic valves. The SCCA valves demonstrated sufficient resistance to burst (above 100 mBar), including after receiving radiotherapy (RT) doses of up to 8 Gy combined with standard 37 °C incubation for up to 7 days, enabling the simultaneous synthesis of multiple spheroids from different cell lines on the same array. Our results suggest that SCCA would be an asset in drug discovery processes, seeking to identify combinatorial treatments. PMID:28976942

A new strategy for array optimization applied to Brazilian Decimetric Array

NASA Astrophysics Data System (ADS)

Faria, C.; Stephany, S.; Sawant, H. S.

Radio interferometric arrays measure the Fourier transform of the sky brightness distribution in a finite set of points that are determined by the cross-correlation of different pairs of antennas of the array The sky brightness distribution is reconstructed by the inverse Fourier transform of the sampled visibilities The quality of the reconstructed images strongly depends on the array configuration since it determines the sampling function and therefore the points in the Fourier Plane This work proposes a new optimization strategy for the array configuration that is based on the entropy of the distribution of the samples points in the Fourier plane A stochastic optimizer the Ant Colony Optimization employs entropy of the point distribution in the Fourier plane to iteratively refine the candidate solutions The proposed strategy was developed for the Brazilian Decimetric Array BDA a radio interferometric array that is currently being developed for solar observations at the Brazilian Institute for Space Research Configurations results corresponding to the Fourier plane coverage synthesized beam and side lobes levels are shown for an optimized BDA configuration obtained with the proposed strategy and compared to the results for a standard T array configuration that was originally proposed

Analysis and Modeling of Shear Waves Generated by Explosions at the San Andreas Fault Observatory at Depth

DTIC Science & Technology

2011-09-01

No. BAA09-69 ABSTRACT Using multiple deployments of an 80-element, three-component borehole seismic array stretching from the surface to 2.3 km...NNSA). 14. ABSTRACT Using multiple deployments of an 80-element, three-component borehole seismic array stretching from the surface to 2.3 km depth...generated using the direct Green’s function (DGF) method of Friederich and Dalkolmo (1995). This method synthesizes the seismic wavefield for a spherically

5[prime] to 3[prime] nucleic acid synthesis using 3[prime]-photoremovable protecting group

DOEpatents

Pirrung, M.C.; Shuey, S.W.; Bradley, J.C.

1999-06-01

The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5[prime] to 3[prime] nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5[prime] end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

Differently ordered TiO2 nanoarrays regulated by solvent polarity, and their photocatalytic performances

NASA Astrophysics Data System (ADS)

Hu, Wenyuan; Dong, Faqin; Zhang, Jing; Liu, Mingxue; He, Huichao; Wu, Yadong; Yang, Dingming; Deng, Hongquan

2018-06-01

Special TiO2 arrays with exposed facets were prepared in different solvents by low- temperature solvothermal synthesis. The morphology, phase and photocatalytic performance influenced by the various solvent polarities were characterized using field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectra and electrochemical testing. The results show that differences of solvent polarity are the main force driving differences in array growth; therefore, anatase TiO2 arrays with different crystal facets can be synthesized by tuning solvent polarity. TiO2 arrays prepared in cyclohexane are the best at oxidizing methyl orange through photocatalysis, followed by arrays prepared in toluene and ethanol. Arrays prepared in toluene are the best at reducing Cr(VI) photocatalytically, followed by those prepared in cyclohexane and ethanol. These differences in photocatalytic power are due to the ratio among the different crystal facets that are exposed, which affects the migration behavior of the photogenerated electrons and holes. In addition, the probable growth mechanisms of self-assembled ordered TiO2 arrays in different solvents are described.

LIPID BIOMARKER CHARACTERIZATION OF BLOOM-RELATED DINOFLAGELLATES AND OTHER EUKARYOTIC ALGAE

EPA Science Inventory

Marine eukaryotic algae synthesize an array of lipids of chemotaxonomic utility that are potentially valuable in characterizing phytoplankton communities. Sterols and photopigments characteristic of dinoflagellates are rarely found in other algal classes. Long chain (C28) highly ...

Ordered Array of Gold Nanoparticles Promoted by Functional Peptides

NASA Astrophysics Data System (ADS)

Matsukawa, Nozomu; Yamashita, Ichiro

2011-05-01

It was successfully demonstrated that 5-nm-diameter gold nanoparticles (GNPs) with 15% size distribution, the surface of which was modified by the synthesized peptides composed of the carbonaceous material affinity peptide (NHBP-1), linker of 11 amino acids and C-terminal cysteine, self-assembled into a two-dimensional (2D) ordered array on a silicon substrate in a spin drying process. NHBP-1 generated an attractive force large enough for the GNP to make 2D collections of GNPs in the course of the spin drying process, and the long linker of 11 amino acids cancelled out the ill effect of size distribution of GNP on the 2D ordered array formation.

Reproduction of a higher-order circular harmonic field using a linear array of loudspeakers.

PubMed

Lee, Jung-Min; Choi, Jung-Woo; Kim, Yang-Hann

2015-03-01

This paper presents a direct formula for reproducing a sound field consisting of higher-order circular harmonics with polar phase variation. Sound fields with phase variation can be used for synthesizing various spatial attributes, such as the perceived width or the location of a virtual sound source. To reproduce such a sound field using a linear loudspeaker array, the driving function of the array is derived in the format of an integral formula. The proposed function shows fewer reproduction errors than a conventional formula focused on magnitude variations. In addition, analysis of the sweet spot reveals that its shape can be asymmetric, depending on the order of harmonics.

Photolithographic Synthesis of High-Density DNA and RNA Arrays on Flexible, Transparent, and Easily Subdivided Plastic Substrates.

PubMed

Holden, Matthew T; Carter, Matthew C D; Wu, Cheng-Hsien; Wolfer, Jamison; Codner, Eric; Sussman, Michael R; Lynn, David M; Smith, Lloyd M

2015-11-17

The photolithographic fabrication of high-density DNA and RNA arrays on flexible and transparent plastic substrates is reported. The substrates are thin sheets of poly(ethylene terephthalate) (PET) coated with cross-linked polymer multilayers that present hydroxyl groups suitable for conventional phosphoramidite-based nucleic acid synthesis. We demonstrate that by modifying array synthesis procedures to accommodate the physical and chemical properties of these materials, it is possible to synthesize plastic-backed oligonucleotide arrays with feature sizes as small as 14 μm × 14 μm and feature densities in excess of 125 000/cm(2), similar to specifications attainable using rigid substrates such as glass or glassy carbon. These plastic-backed arrays are tolerant to a wide range of hybridization temperatures, and improved synthetic procedures are described that enable the fabrication of arrays with sequences up to 50 nucleotides in length. These arrays hybridize with S/N ratios comparable to those fabricated on otherwise identical arrays prepared on glass or glassy carbon. This platform supports the enzymatic synthesis of RNA arrays and proof-of-concept experiments are presented showing that the arrays can be readily subdivided into smaller arrays (or "millichips") using common laboratory-scale laser cutting tools. These results expand the utility of oligonucleotide arrays fabricated on plastic substrates and open the door to new applications for these important bioanalytical tools.

One-pot synthesis of NiO/Mn2O3 nanoflake arrays and their application in electrochemical biosensing

NASA Astrophysics Data System (ADS)

Wang, Yao; Cui, Jiewu; Luo, Lan; Zhang, Jingcheng; Wang, Yan; Qin, Yongqiang; Zhang, Yong; Shu, Xia; Lv, Jun; Wu, Yucheng

2017-11-01

The exploration of novel nanomaterials employed as substrate to construct glucose biosensors is still of significance in the field of clinical diagnosis. In this work, NiO/Mn2O3 nanoflake arrays were synthesized by hydrothermal approach in combination with calcination process. As-prepared NiO/Mn2O3 nanoflake arrays were utilized to construct electrochemical biosensors for glucose detection. NiO/Mn2O3 nanoflake arrays were investigated systematically by scanning electron microscopy (SEM), X-ray diffractionmeter (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy, the formation mechanism of NiO/Mn2O3 nanoflake arrays was proposed. As-prepared glucose biosensors based on NiO/Mn2O3 nanoflake arrays were characterized by cyclic voltammgrams and chronoamperometry. The results indicated that glucose biosensors based on optimized NiO/Mn2O3 nanoflake arrays exhibited a high sensitivity of 167.0 μA mM-1 Cm-2 and good anti-interference ability, suggesting the NiO/Mn2O3 nanoflake arrays are an attractive substrate for the construction of oxidase-based biosensors.

Protein assay structured on paper by using lithography

NASA Astrophysics Data System (ADS)

Wilhelm, E.; Nargang, T. M.; Al Bitar, W.; Waterkotte, B.; Rapp, B. E.

2015-03-01

There are two main challenges in producing a robust, paper-based analytical device. The first one is to create a hydrophobic barrier which unlike the commonly used wax barriers does not break if the paper is bent. The second one is the creation of the (bio-)specific sensing layer. For this proteins have to be immobilized without diminishing their activity. We solve both problems using light-based fabrication methods that enable fast, efficient manufacturing of paper-based analytical devices. The first technique relies on silanization by which we create a flexible hydrophobic barrier made of dimethoxydimethylsilane. The second technique demonstrated within this paper uses photobleaching to immobilize proteins by means of maskless projection lithography. Both techniques have been tested on a classical lithography setup using printed toner masks and on a lithography system for maskless lithography. Using these setups we could demonstrate that the proposed manufacturing techniques can be carried out at low costs. The resolution of the paper-based analytical devices obtained with static masks was lower due to the lower mask resolution. Better results were obtained using advanced lithography equipment. By doing so we demonstrated, that our technique enables fabrication of effective hydrophobic boundary layers with a thickness of only 342 μm. Furthermore we showed that flourescine-5-biotin can be immobilized on the non-structured paper and be employed for the detection of streptavidinalkaline phosphatase. By carrying out this assay on a paper-based analytical device which had been structured using the silanization technique we proofed biological compatibility of the suggested patterning technique.

Maskless selective laser patterning of PEDOT:PSS on barrier/foil for organic electronics applications

NASA Astrophysics Data System (ADS)

Karnakis, Dimitris; Stephens, Tim; Chabrol, Gregoire

2013-03-01

Rapid developments in organic electronics promise low cost devices for applications such as OLED, organic transistors and organic photovoltaics on large-area glass or flexible substrates in the near future. The technology is very attractive as most device layers can be solution printed. But when directly patterned deposition is impossible, a post-patterning step is required and laser processing is gradually emerging as a key-enabling tool. DPSS lasers offer several advantages including maskless, non-contact, dry patterning, but also scalable large area processing, well suited to roll-to-roll manufacturing at μm resolutions. However, very few reports discuss in detail the merits of DPSS laser patterning technology, especially on flexible substrates. This paper describes the potential of ultrafast DPSS laser technology for OLED fabrication on foil and, specifically, picosecond laser ablation of PEDOT:PSS on multilayered barrier/foil or metal grids aimed as a synthetic alternative to inorganic transparent conductive electrodes. Key requirements include: (a) the complete removal of PEDOT layers without residue, (b) the complete absence of surface contamination from redeposited laser debris to avoid short circuiting and (c) no loss in performance of from laser exposure. We will demonstrate that with careful optimisation and appropriate choice of ultrafast laser, the above criteria can be fulfilled. A suitable process window exists resulting in clean laser structuring without damage to the underlying heat sensitive barrier layers whilst also containing laser debris. A low temperature ablation most likely proceeds via a stress-assisted (film fracture and ejection) process as opposed to vaporisation or other phase change commonly encountered with longer pulse lasers.

High speed, mask-less, laser controlled deposition of microscale tungsten tracks using 405 nm wavelength diode laser

NASA Astrophysics Data System (ADS)

Ten, Jyi Sheuan; Sparkes, Martin; O'Neill, William

2017-02-01

A rapid, mask-less deposition technique for the deposition of conductive tracks to nano- and micro-devices has been developed. The process uses a 405 nm wavelength laser diode for the direct deposition of tungsten tracks on silicon substrates via laser assisted chemical vapour deposition. Unlike lithographic processes this technique is single step and does not require chemical masks that may contaminate the substrate. To demonstrate the process, tungsten was deposited from tungsten hexacarbonyl precursors to produce conductive tracks with widths of 1.7-28 μm and heights of 0.05-35 μm at laser scan speeds up to 40 μm/s. The highest volumetric deposition rate achieved is 1×104 μm3/s, three orders of magnitude higher than that of focused ion beam deposition and on par with a 515 nm wavelength argon ion laser previously reported as the laser source. The microstructure and elemental composition of the deposits are comparable to that of largearea chemical vapour deposition methods using the same chemical precursor. The contact resistance and track resistance of the deposits has been measured using the transfer length method to be 205 μΩ cm. The deposition temperature has been estimated at 334 °C from a laser heat transfer model accounting for temperature dependent optical and physical properties of the substrate. The peak temperatures achieved on silicon and other substrates are higher than the thermal dissociation temperature of numerous precursors, indicating that this technique can also be used to deposit other materials such as gold and platinum on various substrates.

Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

PubMed Central

Li, Zhiyang; Leung, Calvin; Gao, Fan; Gu, Zhiyong

2015-01-01

In this paper, vertically aligned Pt nanowire arrays (PtNWA) with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H2O2) detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO) template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM−1·cm−2) among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water) was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors. PMID:26404303

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

PubMed

Hansen, Lajla Bruntse; Buus, Soren; Schafer-Nielsen, Claus

2013-01-01

We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2). Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA) as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids) at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA) and from rabbit serum albumin (RSA) were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Plasmonic resonances in ordered and disordered aluminum nanocavities arrays.

NASA Astrophysics Data System (ADS)

Campuzano, R. G.; Mendoza, D.

2017-01-01

Nanocavities arrays were synthesized by electrochemical anodization of aluminum using oxalic and phosphoric acids as electrolytes. The morphology and topography of these structures were evaluated by SEM and AFM. Plasmonic properties of Al cavities arrays with different ordering and dimensions were analysed based on specular reflectivity. Al cavities arrays fabricated with phosphoric acid dramatically reduced the optical reflectivity as compared with unstructured Al. At the same time pronounced reflectivity dips were detectable in the 300nm-400nm range, which were ascribed to (0,1) plasmonic mode, and also a colored appearance in the samples is noticeably depending on the observation angle. These changes are not observed in samples made with oxalic acid and this fact was explained, based on a theoretical model, in terms that the surface plasmons are excited far in the UV range.

Si/InGaN core/shell hierarchical nanowire arrays and their photoelectrochemical properties.

PubMed

Hwang, Yun Jeong; Wu, Cheng Hao; Hahn, Chris; Jeong, Hoon Eui; Yang, Peidong

2012-03-14

Three-dimensional hierarchical nanostructures were synthesized by the halide chemical vapor deposition of InGaN nanowires on Si wire arrays. Single phase InGaN nanowires grew vertically on the sidewalls of Si wires and acted as a high surface area photoanode for solar water splitting. Electrochemical measurements showed that the photocurrent density with hierarchical Si/InGaN nanowire arrays increased by 5 times compared to the photocurrent density with InGaN nanowire arrays grown on planar Si (1.23 V vs RHE). High-resolution transmission electron microscopy showed that InGaN nanowires are stable after 15 h of illumination. These measurements show that Si/InGaN hierarchical nanostructures are a viable high surface area electrode geometry for solar water splitting. © 2012 American Chemical Society

Lessons from 455 Fusarium polyketide synthases

USDA-ARS?s Scientific Manuscript database

In fungi, polyketide synthases (PKSs) synthesize a structurally diverse array of secondary metabolites (SMs) with a range of biological activities. The most studied SMs are toxic to animals and/or plants, alter plant growth, have beneficial pharmaceutical activities, and/or are brightly colored pigm...

Metamaterial absorber for molecular detection and identification (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tanaka, Takuo

2017-03-01

Metamaterial absorber was used for a background-suppressed surface-enhanced molecular detection technique. By utilizing the resonant coupling between plasmonic modes of a metamaterial absorber and infrared (IR) vibrational modes of a self-assembled monolayer (SAM), attomole level molecular sensitivity was experimentally demonstrated. IR absorption spectroscopy of molecular vibrations is of importance in chemical, material, medical science and so on, since it provides essential information of the molecular structure, composition, and orientation. In the vibrational spectroscopic techniques, in addition to the weak signals from the molecules, strong background degrades the signal-to-noise ratio, and suppression of the background is crucial for the further improvement of the sensitivity. Here, we demonstrate low-background resonant Surface enhanced IR absorption (SEIRA) by using the metamaterial IR absorber that offers significant background suppression as well as plasmonic enhancement. By using mask-less laser lithography technique, metamaterial absorber which consisted of 1D array of Au micro-ribbons on a thick Au film separated by a transparent gap layer made of MgF2 was fabricated. This metamaterial structure was designed to exhibit an anomalous IR absorption at 3000 cm-1, which spectrally overlapped with C-H stretching vibrational modes. 16-Mercaptohexadecanoic acid (16-MHDA) was used as a test molecule, which formed a 2-nm thick SAM with their thiol head-group chemisorbed on the Au surface. In the FTIR measurements, the symmetric and asymmetric C-H stretching modes were clearly observed as reflection peaks within a broad plasmonic absorption of the metamaterial, and 1.8 attomole molecular sensitivity was experimentally demonstrated.

Single conducting polymer nanowire based conductometric sensors

NASA Astrophysics Data System (ADS)

Bangar, Mangesh Ashok

The detection of toxic chemicals, gases or biological agents at very low concentrations with high sensitivity and selectivity has been subject of immense interest. Sensors employing electrical signal readout as transduction mechanism offer easy, label-free detection of target analyte in real-time. Traditional thin film sensors inherently suffered through loss of sensitivity due to current shunting across the charge depleted/added region upon analyte binding to the sensor surface, due to their large cross sectional area. This limitation was overcome by use of nanostructure such as nanowire/tube as transducer where current shunting during sensing was almost eliminated. Due to their benign chemical/electrochemical fabrication route along with excellent electrical properties and biocompatibility, conducting polymers offer cost-effective alternative over other nanostructures. Biggest obstacle in using these nanostructures is lack of easy, scalable and cost-effective way of assembling these nanostructures on prefabricated micropatterns for device fabrication. In this dissertation, three different approaches have been taken to fabricate individual or array of single conducting polymer (and metal) nanowire based devices and using polymer by itself or after functionalization with appropriate recognition molecule they have been applied for gas and biochemical detection. In the first approach electrochemical fabrication of multisegmented nanowires with middle functional Ppy segment along with ferromagnetic nickel (Ni) and end gold segments for better electrical contact was studied. This multi-layered nanowires were used along with ferromagnetic contact electrode for controlled magnetic assembly of nanowires into devices and were used for ammonia gas sensing. The second approach uses conducting polymer, polypyrrole (Ppy) nanowires using simple electrophoretic alignment and maskless electrodeposition to anchor nanowire which were further functionalized with antibodies against cancer marker protein (Cancer Antigen, CA 125) using covalent immobilization for detection of CA 125 in buffer and human blood plasma. Third approach combined electrochemical deposition of conducting polymer and assembly steps into a single step fabrication & functionalization using e-beam lithographically patterned nano-channels. Using this method array of Ppy nanowires were fabricated. Further during fabrication step, by entrapping recognition molecule (avidin) biofunctionalization was achieved. Subsequently these sensors were used for detection of biotinylated single stranded DNA.

A new method to synthesize complicated multi-branched carbon nanotubes with controlled architecture and composition.

PubMed

Wei, Dacheng; Liu, Yunqi; Cao, Lingchao; Fu, Lei; Li, Xianglong; Wang, Yu; Yu, Gui; Zhu, Daoben

2006-02-01

Here we develop a simple method by using flow fluctuation to synthesize arrays of multi-branched carbon nanotubes (CNTs) that are far more complex than those previously reported. The architectures and compositions can be well controlled, thus avoiding any template or additive. A branching mechanism of fluctuation-promoted coalescence of catalyst particles is proposed. This finding will provide a hopeful approach to the goal of CNT-based integrated circuits and be valuable for applying branched junctions in nanoelectronics and producing branched junctions of other materials.

Electron microscopy investigation of gallium oxide micro/nanowire structures synthesized via vapor phase growth.

PubMed

Wang, Y; Xu, J; Wang, R M; Yu, D P

2004-01-01

Large-scale micro/nanosized Ga(2)O(3) structures were synthesized via a simple vapor p9hase growth method. The morphology of the as-grown structures varied from aligned arrays of smooth nano/microscale wires to composite and complex microdendrites. We present evidence that the formation of the observed structure depends strongly on its position relative to the source materials (the concentration distribution) and on the growth temperature. A growth model is proposed, based on the vapor-solid (VS) mechanism, which can explain the observed morphologies.

Template-assisted fabrication of tin and antimony based nanowire arrays

NASA Astrophysics Data System (ADS)

Zaraska, Leszek; Kurowska, Elżbieta; Sulka, Grzegorz D.; Jaskuła, Marian

2012-10-01

Antimony nanowires with diameters ranging from 35 nm to 320 nm were successfully prepared by simple, galvanostatic electrodeposition inside the pores of anodic alumina membranes from a citrate based electrolyte. The use of the potassium antimonyl tartrate electrolyte for electrodeposition results in the formation of Sb/Sb2O3 nanowires. The structural features of the nanowire arrays were investigated by FE-SEM, and the nanowire composition was confirmed by EDS and XRD measurements. A distinct peak at about 27.5° in the XRD pattern recorded for nanowires formed in the tartrate electrolyte was attributed to the presence of co-deposited Sb2O3. Three types of dense arrays of Sn-SnSb nanowires with diameters ranging from 82 nm to 325 nm were also synthesized by DC galvanostatic electrodeposition into the anodic aluminum oxide (AAO) membranes for the first time. Only Sn and SnSb peaks appeared in the XRD pattern and both phases seem to have a relatively high degree of crystallinity. The influence of current density applied during electrodeposition on the composition of nanowires was investigated. It was found that the Sb content in fabricated nanowires decreases with increasing current density. The diameters of all synthesized nanowires roughly correspond to the dimensions of the nanochannels of AAO templates used for electrodeposition.

Structural and optical properties of glancing angle deposited In2O3 columnar arrays and Si/In2O3 photodetector

NASA Astrophysics Data System (ADS)

Mondal, A.; Shougaijam, B.; Goswami, T.; Dhar, J. C.; Singh, N. K.; Choudhury, S.; Chattopadhay, K. K.

2014-04-01

Ordered and perpendicular columnar arrays of In2O3 were synthesized on conducting ITO electrode by a simple glancing angle deposition (GLAD) technique. The as-deposited In2O3 columns were investigated by field emission gun-scanning electron microscope (FEG-SEM). The average length and diameter of the columns were estimated ˜400 nm and ˜100 nm, respectively. The morphology of the structure was examined by transmission electron microscopy (TEM). X-ray diffraction (XRD) analysis shows the polycrystalline nature of the sample which was verified by selective area electron diffraction (SAED) analysis. The growth mechanism and optical properties of the columns were also discussed. Optical absorption shows that In2O3 columns have a high band to band transition at ˜3.75 eV. The ultraviolet and green emissions were obtained from the In2O3 columnar arrays. The P-N junction was formed between In2O3 and P-type Si substrate. The GLAD synthesized In2O3 film exhibits low current conduction compared to In2O3 TF. However, the Si/GLAD-In2O3 detector shows ˜1.5 times enhanced photoresponsivity than that of Si/In2O3 TF.

Magnetic-optical bifunctional CoPt3/Co multilayered nanowire arrays

NASA Astrophysics Data System (ADS)

Su, Yi-Kun; Yan, Zhi-Long; Wu, Xi-Ming; Liu, Huan; Ren, Xiao; Yang, Hai-Tao

2015-10-01

CoPt3/Co multilayered nanowire (NW) arrays are synthesized by pulsed electrodeposition into nanoporous anodic aluminum oxide (AAO) templates. The electrochemistry deposition parameters are determined by cyclic voltammetry to realize the well control of the ratio of Co to Pt and the length of every segment. The x-ray diffraction (XRD) patterns show that both Co and CoPt3 NWs exhibit face-centered cubic (fcc) structures. In the UV-visible absorption spectra, CoPt3/Co NW arrays show a red-shift with respect to pure CoPt3NWs. Compared with the pure Co nanowire arrays, the CoPt3/Co multilayered nanowire arrays show a weak shape anisotropy and well-modulated magnetic properties. CoPt3/Co multilayered nanowires are highly encouraging that new families of bimetallic nanosystems may be developed to meet the needs of nanomaterials in emerging multifunctional nanotechnologies. Project supported by the National Natural Science Foundation of China (Grant Nos. 51472165, 51471185, and 11274370).

One-dimensional ferromagnetic array compound [Co3(SBA)2(OH)2(H2O)2]n, (SBA = 4-sulfobenzoate)

NASA Astrophysics Data System (ADS)

Honda, Zentaro; Nomoto, Naoyuki; Fujihara, Takashi; Hagiwara, Masayuki; Kida, Takanori; Sawada, Yuya; Fukuda, Takeshi; Kamata, Norihiko

2018-06-01

We report on the syntheses, crystal structure, and magnetic properties of the transition metal coordination polymer [Co3(SBA)2(OH)2(H2O)2]n, (SBA = 4-sulfobenzoate) in which CoO6 octahedra are linked through their edges, forming one-dimensional (1D) Co(II) arrays running along the crystal a-axis. These arrays are further perpendicularly bridged by SBA ligand to construct a three-dimensional framework. Its magnetic properties have been investigated, and ferromagnetic interactions within the arrays have been found. From heat capacity measurements, we have found that this compound exhibits a three-dimensional ferromagnetic phase transition at TC = 1.54 K, and the specific heat just above TC shows a Schottky anomaly which originates from an energy gap caused by uniaxial magnetic anisotropy. These results suggest that [Co3(SBA)2(OH)2(H2O)2]n consists of weakly coupled 1D ferromagnetic Ising arrays.

A software framework for pipelined arithmetic algorithms in field programmable gate arrays

NASA Astrophysics Data System (ADS)

Kim, J. B.; Won, E.

2018-03-01

Pipelined algorithms implemented in field programmable gate arrays are extensively used for hardware triggers in the modern experimental high energy physics field and the complexity of such algorithms increases rapidly. For development of such hardware triggers, algorithms are developed in C++, ported to hardware description language for synthesizing firmware, and then ported back to C++ for simulating the firmware response down to the single bit level. We present a C++ software framework which automatically simulates and generates hardware description language code for pipelined arithmetic algorithms.

Synthesis of high crystallinity ZnO nanowire array on polymer substrate and flexible fiber-based sensor.

PubMed

Liu, Jinmei; Wu, Weiwei; Bai, Suo; Qin, Yong

2011-11-01

Well aligned ZnO nanowire (NW) arrays are grown on Kevlar fiber and Kapton film via the chemical vapor deposition (CVD) method. These NWs have better crystallinity than those synthesized through the low-temperature hydrothermal method. The average length and diameter of ZnO NWs grown on Kevlar fiber can be controlled from 0.5 to 2.76 μm and 30 to 300 nm, respectively. A flexible ultraviolet (UV) sensor based on Kevlar fiber/ZnO NWs hybrid structure is made to detect UV illumination quantificationally.

Hierarchical sinuous-antenna phased array for millimeter wavelengths

NASA Astrophysics Data System (ADS)

Cukierman, Ari; Lee, Adrian T.; Raum, Christopher; Suzuki, Aritoki; Westbrook, Benjamin

2018-03-01

We present the design, fabrication, and measured performance of a hierarchical sinuous-antenna phased array coupled to superconducting transition-edge-sensor (TES) bolometers for millimeter wavelengths. The architecture allows for dual-polarization wideband sensitivity with a beam width that is approximately frequency-independent. We report on measurements of a prototype device, which uses three levels of triangular phased arrays to synthesize beams that are approximately constant in width across three frequency bands covering a 3:1 bandwidth. The array element is a lens-coupled sinuous antenna. The device consists of an array of hemispherical lenses coupled to a lithographed wafer, which integrates TESs, planar sinuous antennas, and microwave circuitry including band-defining filters. The approximately frequency-independent beam widths improve coupling to telescope optics and keep the sensitivity of an experiment close to optimal across a broad frequency range. The design can be straightforwardly modified for use with non-TES lithographed cryogenic detectors such as kinetic inductance detectors. Additionally, we report on the design and measurements of a broadband 180° hybrid that can simplify the design of future multichroic focal planes including but not limited to hierarchical phased arrays.

Brazilian Decimetric Array (BDA) project - Phase II

NASA Astrophysics Data System (ADS)

Faria, C.; Stephany, S.; Sawant, H. S.; Cecatto, J. R.; Fernandes, F. C. R.

2010-02-01

The configuration of the second phase of the Brazilian Decimetric Array (BDA), installed at Cachoeira Paulista, Brazil (Longitude 45° 0‧ 20″ W and Latitude 22° 41‧ 19″ S), is a T-shaped array where 21 antennas are being added to existing 5 antennas of the first phase. In the third phase, in each arm of the T array, four more antennas will be added and baselines will be increased to 2.5 × 1.25 km in east-west and south directions, respectively. The antennas will be equally spaced at the distances of 250 meters from the central antenna of the T-array. Also, the frequency range will be increased to 1.2-1.7, 2.8 and 5.6 GHz. The Second phase of the BDA should be operational by the middle of 2010 and will operate in the frequency range of (1.2-1.7) GHz for solar and non solar observations. Here, we present the characteristics of the second phase of the BDA project, details of the array configuration, the u-v coverage, the synthesized beam obtained for the proposed configuration.

Particle-Based Microarrays of Oligonucleotides and Oligopeptides.

PubMed

Nesterov-Mueller, Alexander; Maerkle, Frieder; Hahn, Lothar; Foertsch, Tobias; Schillo, Sebastian; Bykovskaya, Valentina; Sedlmayr, Martyna; Weber, Laura K; Ridder, Barbara; Soehindrijo, Miriam; Muenster, Bastian; Striffler, Jakob; Bischoff, F Ralf; Breitling, Frank; Loeffler, Felix F

2014-10-28

In this review, we describe different methods of microarray fabrication based on the use of micro-particles/-beads and point out future tendencies in the development of particle-based arrays. First, we consider oligonucleotide bead arrays, where each bead is a carrier of one specific sequence of oligonucleotides. This bead-based array approach, appearing in the late 1990s, enabled high-throughput oligonucleotide analysis and had a large impact on genome research. Furthermore, we consider particle-based peptide array fabrication using combinatorial chemistry. In this approach, particles can directly participate in both the synthesis and the transfer of synthesized combinatorial molecules to a substrate. Subsequently, we describe in more detail the synthesis of peptide arrays with amino acid polymer particles, which imbed the amino acids inside their polymer matrix. By heating these particles, the polymer matrix is transformed into a highly viscous gel, and thereby, imbedded monomers are allowed to participate in the coupling reaction. Finally, we focus on combinatorial laser fusing of particles for the synthesis of high-density peptide arrays. This method combines the advantages of particles and combinatorial lithographic approaches.

Particle-Based Microarrays of Oligonucleotides and Oligopeptides

PubMed Central

Nesterov-Mueller, Alexander; Maerkle, Frieder; Hahn, Lothar; Foertsch, Tobias; Schillo, Sebastian; Bykovskaya, Valentina; Sedlmayr, Martyna; Weber, Laura K.; Ridder, Barbara; Soehindrijo, Miriam; Muenster, Bastian; Striffler, Jakob; Bischoff, F. Ralf; Breitling, Frank; Loeffler, Felix F.

2014-01-01

In this review, we describe different methods of microarray fabrication based on the use of micro-particles/-beads and point out future tendencies in the development of particle-based arrays. First, we consider oligonucleotide bead arrays, where each bead is a carrier of one specific sequence of oligonucleotides. This bead-based array approach, appearing in the late 1990s, enabled high-throughput oligonucleotide analysis and had a large impact on genome research. Furthermore, we consider particle-based peptide array fabrication using combinatorial chemistry. In this approach, particles can directly participate in both the synthesis and the transfer of synthesized combinatorial molecules to a substrate. Subsequently, we describe in more detail the synthesis of peptide arrays with amino acid polymer particles, which imbed the amino acids inside their polymer matrix. By heating these particles, the polymer matrix is transformed into a highly viscous gel, and thereby, imbedded monomers are allowed to participate in the coupling reaction. Finally, we focus on combinatorial laser fusing of particles for the synthesis of high-density peptide arrays. This method combines the advantages of particles and combinatorial lithographic approaches. PMID:27600347

Biostable beta-amino acid PK/PBAN analogs: Agonist and antagonist properties

USDA-ARS?s Scientific Manuscript database

The pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) family plays a significant role in a multifunctional array of important physiological processes in insects. PK/PBAN analogs incorporating beta-amino acids were synthesized and evaluated in a pheromonotropic assay in Heliothis pe...

Method of Forming Textured Silicon Substrate by Maskless Cryogenic Etching

NASA Technical Reports Server (NTRS)

Yee, Karl Y. (Inventor); Homyk, Andrew P. (Inventor)

2014-01-01

Disclosed herein is a textured substrate comprising a base comprising silicon, the base having a plurality of needle like structures depending away from the base, wherein at least one of the needle like structures has a depth of greater than or equal to about 50 micrometers determined perpendicular to the base, and wherein at least one of the needle like structures has a width of less than or equal to about 50 micrometers determined parallel to the base. An anode and a lithium ion battery comprising the textured substrate, and a method of producing the textured substrate are also disclosed.

An array of Eiffel-tower-shape AlN nanotips and its field emission properties

NASA Astrophysics Data System (ADS)

Tang, Yongbing; Cong, Hongtao; Chen, Zhigang; Cheng, Huiming

2005-06-01

An array of Eiffel-tower-shape AlN nanotips has been synthesized and assembled vertically with Si substrate by a chemical vapor deposition method at 700 °C. The single-crystalline AlN nanotips along [001] direction, including sharp tips with 10-100 nm in diameter and submicron-sized bases, are distributed uniformly with density of 106-107tips/cm2. Field emission (FE) measurements show that its turn on field is 4.7 V/μm, which is comparable to that of carbon nanotubes, and the fluctuation of FE current is as small as 0.74% for 4 h. It is revealed this nanostructure is available to optimize the FE properties and make the array a promising field emitter.

Soft-solution route to ZnO nanowall array with low threshold power density

NASA Astrophysics Data System (ADS)

Jang, Eue-Soon; Chen, Xiaoyuan; Won, Jung-Hee; Chung, Jae-Hun; Jang, Du-Jeon; Kim, Young-Woon; Choy, Jin-Ho

2010-07-01

ZnO nanowall array (ZNWA) has been directionally grown on the buffer layer of ZnO nanoparticles dip-coated on Si-wafer under a soft solution process. Nanowalls on substrate are in most suitable shape and orientation not only as an optical trap but also as an optical waveguide due to their unique growth habit, V[011¯0]≫V[0001]≈V[0001¯]. Consequently, the stimulated emission at 384 nm through nanowalls is generated by the threshold power density of only 25 kW/cm2. Such UV lasing properties are superior to those of previously reported ZnO nanorod arrays. Moreover, there is no green (defect) emission due to the mild procedure to synthesize ZNWA.

Synthesis and photoluminescence properties of ZnS nanobowl arrays via colloidal monolayer template

PubMed Central

2014-01-01

Two-dimensional Zinc sulfide (ZnS) nanobowl arrays were synthesized via self-assembled monolayer polystyrene sphere template floating on precursor solution surface. A facile approach was proposed to investigate the morphology evolution of nanobowl arrays by post-annealing procedure. Photoluminescence (PL) measurement of as-grown nanoarrays shows that the spectrum mainly includes two parts: a purple emission peak at 382 nm and a broad blue emission band centering at 410 nm with a shoulder around 459 nm, and a blue emission band at 440 nm was obtained after the annealing procedure. ZnS nanoarrays with special morphologies and PL emission are benefits to their promising application in novel photoluminescence nanodevice. PMID:25246857

Fabrication of highly ordered 2D metallic arrays with disc-in-hole binary nanostructures via a newly developed nanosphere lithography

NASA Astrophysics Data System (ADS)

Yang, Xi; Guo, Wei; Wang, Xixi; Liao, Mingdun; Gao, Pingqi; Ye, Jichun

2017-11-01

2D metallic arrays with binary nanostructures derived from a nanosphere lithography (NSL) method have been rarely reported. Here, we demonstrate a novel NSL strategy to fabricate highly ordered 2D gold arrays with disc-in-hole binary (DIHB) nanostructures in large scale by employing a sacrificing layer combined with a three-step lift-off process. The structural parameters of the resultant DIHB arrays, such as periodicity, hole diameter, disc diameter and thicknesses can be facilely controlled by tuning the nanospheres size, etching condition, deposition angle and duration, respectively. Due to the intimate interactions between two subcomponents, the DIHB arrays exhibit both an extraordinary high surface-enhanced Raman scattering enhancement factor up to 5 × 108 and a low sheet resistance down to 1.7 Ω/sq. Moreover, the DIHB array can also be used as a metal catalyzed chemical etching catalytic pattern to create vertically-aligned Si nano-tube arrays for anti-reflectance application. This strategy provides a universal route for synthesizing other diverse binary nanostructures with controlled morphology, and thus expands the applications of the NSL to prepare ordered nanostructures with multi-function.

Hierarchical Mesoporous Zinc-Nickel-Cobalt Ternary Oxide Nanowire Arrays on Nickel Foam as High-Performance Electrodes for Supercapacitors.

PubMed

Wu, Chun; Cai, Junjie; Zhang, Qiaobao; Zhou, Xiang; Zhu, Ying; Shen, Pei Kang; Zhang, Kaili

2015-12-09

Nickel foam supported hierarchical mesoporous Zn-Ni-Co ternary oxide (ZNCO) nanowire arrays are synthesized by a simple two-step approach including a hydrothermal method and subsequent calcination process and directly utilized for supercapacitive investigation for the first time. The nickel foam supported hierarchical mesoporous ZNCO nanowire arrays possess an ultrahigh specific capacitance value of 2481.8 F g(-1) at 1 A g(-1) and excellent rate capability of about 91.9% capacitance retention at 5 A g(-1). More importantly, an asymmetric supercapacitor with a high energy density (35.6 Wh kg(-1)) and remarkable cycle stability performance (94% capacitance retention over 3000 cycles) is assembled successfully by employing the ZNCO electrode as positive electrode and activated carbon as negative electrode. The remarkable electrochemical behaviors demonstrate that the nickel foam supported hierarchical mesoporous ZNCO nanowire array electrodes are highly desirable for application as advanced supercapacitor electrodes.

Continuous needleless electrospinning of magnetic nanofibers from magnetization-induced self-assembling PVA/ferrofluid cone array

NASA Astrophysics Data System (ADS)

Wang, Hongjian; Liu, Bin; Huang, Weilong; Lin, Zi; Luo, Jie; Li, Yan; Zhuang, Lin; Wang, Wei; Jiang, Lelun

2018-04-01

A novel approach, continuous needleless electrospinning from the tips of magnetization-induced self-assembling PVA/ferrofluid cone array, was proposed to prepare magnetic nanofibers. A PVA/ferrofluid was synthesized, the needleless electrospinning process was observed, and the morphology and magnetic properties of magnetic nanofibers were investigated. The results showed that the PVA/ferrofluid could remain stable and homogeneous for 21 days under the magnetic field gradient (2.2 mT/mm). "Taylor cone" array of PVA/ferrofluid was self-assembled under both the magnetic and electric fields. As the electric voltage reached 25 kV, the jets were emitted from the "Taylor cone" array, resulting in needleless electrospinning of magnetic nanofibers. Magnetic nanofibers were homogeneous and continuous with an average diameter of 73.6 nm. Magnetic nanofibers showed a good magnetic response property and relatively high saturated magnetization (1.71 emu/g), which is expected to be applied in the biomedical field.

Multidirectional flexible force sensors based on confined, self-adjusting carbon nanotube arrays

NASA Astrophysics Data System (ADS)

Lee, J.-I.; Pyo, Soonjae; Kim, Min-Ook; Kim, Jongbaeg

2018-02-01

We demonstrate a highly sensitive force sensor based on self-adjusting carbon nanotube (CNT) arrays. Aligned CNT arrays are directly synthesized on silicon microstructures by a space-confined growth technique which enables a facile self-adjusting contact. To afford flexibility and softness, the patterned microstructures with the integrated CNTs are embedded in polydimethylsiloxane structures. The sensing mechanism is based on variations in the contact resistance between the facing CNT arrays under the applied force. By finite element analysis, proper dimensions and positions for each component are determined. Further, high sensitivities up to 15.05%/mN of the proposed sensors were confirmed experimentally. Multidirectional sensing capability could also be achieved by designing multiple sets of sensing elements in a single sensor. The sensors show long-term operational stability, owing to the unique properties of the constituent CNTs, such as outstanding mechanical durability and elasticity.

Plasmonic nanoantenna arrays for surface-enhanced Raman spectroscopy of lipid molecules embedded in a bilayer membrane.

PubMed

Kühler, Paul; Weber, Max; Lohmüller, Theobald

2014-06-25

We demonstrate a strategy for surface-enhanced Raman spectroscopy (SERS) of supported lipid membranes with arrays of plasmonic nanoantennas. Colloidal lithography refined with plasma etching is used to synthesize arrays of triangular shaped gold nanoparticles. Reducing the separation distance between the triangle tips leads to plasmonic coupling and to a strong enhancement of the electromagnetic field in the nanotriangle gap. As a result, the Raman scattering intensity of molecules that are located at this plasmonic "hot-spot" can be increased by several orders of magnitude. The nanoantenna array is then embedded with a supported phospholipid membrane which is fluid at room temperature and spans the antenna gap. This configuration offers the advantage that molecules that are mobile within the bilayer membrane can enter the "hot-spot" region via diffusion and can therefore be measured by SERS without static entrapment or adsorption of the molecules to the antenna itself.

Vocabulary Acquisition: Implications for Reading Comprehension

ERIC Educational Resources Information Center

Wagner, Richard K., Ed.; Muse, Andrea E., Ed.; Tannenbaum, Kendra R., Ed.

2006-01-01

Understanding a text requires more than the ability to read individual words: it depends greatly on vocabulary knowledge. This important book brings together leading literacy scholars to synthesize cutting-edge research on vocabulary development and its connections to reading comprehension. The volume also reviews an array of approaches to…

High-Resolution Graphene Films for Electrochemical Sensing via Inkjet Maskless Lithography.

PubMed

Hondred, John A; Stromberg, Loreen R; Mosher, Curtis L; Claussen, Jonathan C

2017-10-24

Solution-phase printing of nanomaterial-based graphene inks are rapidly gaining interest for fabrication of flexible electronics. However, scalable manufacturing techniques for high-resolution printed graphene circuits are still lacking. Here, we report a patterning technique [i.e., inkjet maskless lithography (IML)] to form high-resolution, flexible, graphene films (line widths down to 20 μm) that significantly exceed the current inkjet printing resolution of graphene (line widths ∼60 μm). IML uses an inkjet printed polymer lacquer as a sacrificial pattern, viscous spin-coated graphene, and a subsequent graphene lift-off to pattern films without the need for prefabricated stencils, templates, or cleanroom technology (e.g., photolithography). Laser annealing is employed to increase conductivity on thermally sensitive, flexible substrates [polyethylene terephthalate (PET)]. Laser annealing and subsequent platinum nanoparticle deposition substantially increases the electroactive nature of graphene as illustrated by electrochemical hydrogen peroxide (H 2 O 2 ) sensing [rapid response (5 s), broad linear sensing range (0.1-550 μm), high sensitivity (0.21 μM/μA), and low detection limit (0.21 μM)]. Moreover, high-resolution, complex graphene circuits [i.e., interdigitated electrodes (IDE) with varying finger width and spacing] were created with IML and characterized via potassium chloride (KCl) electrochemical impedance spectroscopy (EIS). Results indicated that sensitivity directly correlates to electrode feature size as the IDE with the smallest finger width and spacing (50 and 50 μm) displayed the largest response to changes in KCl concentration (∼21 kΩ). These results indicate that the developed IML patterning technique is well-suited for rapid, solution-phase graphene film prototyping on flexible substrates for numerous applications including electrochemical sensing.

Printed Graphene Electrochemical Biosensors Fabricated by Inkjet Maskless Lithography for Rapid and Sensitive Detection of Organophosphates.

PubMed

Hondred, John A; Breger, Joyce C; Alves, Nathan J; Trammell, Scott A; Walper, Scott A; Medintz, Igor L; Claussen, Jonathan C

2018-04-04

Solution phase printing of graphene-based electrodes has recently become an attractive low-cost, scalable manufacturing technique to create in-field electrochemical biosensors. Here, we report a graphene-based electrode developed via inkjet maskless lithography (IML) for the direct and rapid monitoring of triple-O linked phosphonate organophosphates (OPs); these constitute the active compounds found in chemical warfare agents and pesticides that exhibit acute toxicity as well as long-term pollution to soils and waterways. The IML-printed graphene electrode is nano/microstructured with a 1000 mW benchtop laser engraver and electrochemically deposited platinum nanoparticles (dia. ∼25 nm) to improve its electrical conductivity (sheet resistance decreased from ∼10 000 to 100 Ω/sq), surface area, and electroactive nature for subsequent enzyme functionalization and biosensing. The enzyme phosphotriesterase (PTE) was conjugated to the electrode surface via glutaraldehyde cross-linking. The resulting biosensor was able to rapidly measure (5 s response time) the insecticide paraoxon (a model OP) with a low detection limit (3 nM), and high sensitivity (370 nA/μM) with negligible interference from similar nerve agents. Moreover, the biosensor exhibited high reusability (average of 0.3% decrease in sensitivity per sensing event), stability (90% anodic current signal retention over 1000 s), longevity (70% retained sensitivity after 8 weeks), and the ability to selectively sense OP in actual soil and water samples. Hence, this work presents a scalable printed graphene manufacturing technique that can be used to create OP biosensors that are suitable for in-field applications as well as, more generally, for low-cost biosensor test strips that could be incorporated into wearable or disposable sensing paradigms.

Mask-less deposition of Au-SnO2 nanocomposites on CMOS MEMS platform for ethanol detection.

PubMed

Santra, S; Sinha, A K; De Luca, A; Ali, S Z; Udrea, F; Guha, P K; Ray, S K; Gardner, J W

2016-03-29

Here we report on the mask-less deposition of Au-SnO2 nanocomposites with a silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) micro electro mechanical system (MEMS) platform through the use of dip pen nanolithography (DPN) to create a low-cost ethanol sensor. MEMS technology is used in order to achieve low power consumption, by the employment of a membrane structure formed using deep reactive ion etching technique. The device consists of an embedded tungsten micro-heater with gold interdigitated electrodes on top of the SOI membrane. The tungsten micro-heater is used to raise the membrane temperature up to its operating temperature and the electrodes are used to measure the resistance of the nanocomposite sensing layer. The CMOS MEMS devices have high electro-thermal efficiency, with 8.2 °C temperature increase per mW power of consumption. The sensing material (Au-SnO2 nanocomposite) was synthesised starting from SnO nanoplates, then Au nanoparticles were attached chemically to the surface of SnO nanoplates, finally the mixture was heated at 700 °C in an oven in air for 4 h. This composite material was sonicated for 2 h in terpineol to make a viscous homogeneous slurry and then 'written' directly across the electrode area using the DPN technique without any mask. The devices were characterised by exposure to ethanol vapour in humid air in the concentration range of 100-1000 ppm. The sensitivity varied from 1.2 to 0.27 ppm(-1) for 100-1000 ppm of ethanol at 10% relative humid air. Selectivity measurements showed that the sensors were selective towards ethanol when they were exposed to acetone and toluene.

Mask-less deposition of Au-SnO2 nanocomposites on CMOS MEMS platform for ethanol detection

NASA Astrophysics Data System (ADS)

Santra, S.; Sinha, A. K.; De Luca, A.; Ali, S. Z.; Udrea, F.; Guha, P. K.; Ray, S. K.; Gardner, J. W.

2016-03-01

Here we report on the mask-less deposition of Au-SnO2 nanocomposites with a silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) micro electro mechanical system (MEMS) platform through the use of dip pen nanolithography (DPN) to create a low-cost ethanol sensor. MEMS technology is used in order to achieve low power consumption, by the employment of a membrane structure formed using deep reactive ion etching technique. The device consists of an embedded tungsten micro-heater with gold interdigitated electrodes on top of the SOI membrane. The tungsten micro-heater is used to raise the membrane temperature up to its operating temperature and the electrodes are used to measure the resistance of the nanocomposite sensing layer. The CMOS MEMS devices have high electro-thermal efficiency, with 8.2 °C temperature increase per mW power of consumption. The sensing material (Au-SnO2 nanocomposite) was synthesised starting from SnO nanoplates, then Au nanoparticles were attached chemically to the surface of SnO nanoplates, finally the mixture was heated at 700 °C in an oven in air for 4 h. This composite material was sonicated for 2 h in terpineol to make a viscous homogeneous slurry and then ‘written’ directly across the electrode area using the DPN technique without any mask. The devices were characterised by exposure to ethanol vapour in humid air in the concentration range of 100-1000 ppm. The sensitivity varied from 1.2 to 0.27 ppm-1 for 100-1000 ppm of ethanol at 10% relative humid air. Selectivity measurements showed that the sensors were selective towards ethanol when they were exposed to acetone and toluene.

Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim

We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm -3 carrier density, and ~0.1 cm 2 V -1 s -1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstratemore » the potential application of infiltration synthesis in fabricating metal oxide electronic devices.« less

Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

DOE PAGES

Chang-Yong Nam; Stein, Aaron; Kisslinger, Kim; ...

2015-11-17

We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ~1019 cm -3 carrier density, and ~0.1 cm 2 V -1 s -1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstratemore » the potential application of infiltration synthesis in fabricating metal oxide electronic devices.« less

Free-standing, well-aligned ordered mesoporous carbon nanofibers on current collectors for high-power micro-supercapacitors.

PubMed

Kang, Eunae; Jeon, Gumhye; Kim, Jin Kon

2013-07-21

The mesoporous carbon nanofiber arrays that stand on carbon-gold double-layer current collectors are synthesized by self-assembly of a PS-b-PEO copolymer and resol in AAO templates for a high-power micro-supercapacitor at high current densities.

Hierarchical Branched Vanadium Oxide Nanorod@Si Nanowire Architecture for High Performance Supercapacitors.

PubMed

Li, Zhaodong; Wang, Fei; Wang, Xudong

2017-01-01

Vanadium oxide (VO x ) nanorods are uniformly synthesized on dense Si nanowire arrays. This 3D hierarchical nanoarchitecture offers a novel high-performance supercapacitor electrode design with significantly improved specific capacitance and high-rate capability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

PubMed

Peled, Itay; Kaminsky, Ron; Kotler, Zvi

2015-06-01

In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%.

Static inverter with synchronous output waveform synthesized by time-optimal-response feedback

NASA Technical Reports Server (NTRS)

Kernick, A.; Stechschulte, D. L.; Shireman, D. W.

1976-01-01

Time-optimal-response 'bang-bang' or 'bang-hang' technique, using four feedback control loops, synthesizes static-inverter sinusoidal output waveform by self-oscillatory but yet synchronous pulse-frequency-modulation (SPFM). A single modular power stage per phase of ac output entails the minimum of circuit complexity while providing by feedback synthesis individual phase voltage regulation, phase position control and inherent compensation simultaneously for line and load disturbances. Clipped sinewave performance is described under off-limit load or input voltage conditions. Also, approaches to high power levels, 3-phase arraying and parallel modular connection are given.

Large-area zinc oxide nanorod arrays templated by nanoimprint lithography: control of morphologies and optical properties

NASA Astrophysics Data System (ADS)

Zhang, Chen; Huang, Xiaohu; Liu, Hongfei; Chua, Soo Jin; Ross, Caroline A.

2016-12-01

Vertically aligned, highly ordered, large area arrays of nanostructures are important building blocks for multifunctional devices. Here, ZnO nanorod arrays are selectively synthesized on Si substrates by a solution method within patterns created by nanoimprint lithography. The growth modes of two dimensional nucleation-driven wedding cakes and screw dislocation-driven spirals are inferred to determine the top end morphologies of the nanorods. Sub-bandgap photoluminescence of the nanorods is greatly enhanced by the manipulation of the hydrogen donors via a post-growth thermal treatment. Lasing behavior is facilitated in the nanorods with faceted top ends formed from wedding cakes growth mode. This work demonstrates the control of morphologies of oxide nanostructures in a large scale and the optimization of the optical performance.

Density-controlled, solution-based growth of ZnO nanorod arrays via layer-by-layer polymer thin films for enhanced field emission

NASA Astrophysics Data System (ADS)

Weintraub, Benjamin; Chang, Sehoon; Singamaneni, Srikanth; Han, Won Hee; Choi, Young Jin; Bae, Joonho; Kirkham, Melanie; Tsukruk, Vladimir V.; Deng, Yulin

2008-10-01

A simple, scalable, and cost-effective technique for controlling the growth density of ZnO nanorod arrays based on a layer-by-layer polyelectrolyte polymer film is demonstrated. The ZnO nanorods were synthesized using a low temperature (T = 90 °C), solution-based method. The density-control technique utilizes a polymer thin film pre-coated on the substrate to control the mass transport of the reactant to the substrate. The density-controlled arrays were investigated as potential field emission candidates. The field emission results revealed that an emitter density of 7 nanorods µm-2 and a tapered nanorod morphology generated a high field enhancement factor of 5884. This novel technique shows promise for applications in flat panel display technology.

Tunable growth of TiO2 nanostructures on Ti substrates

NASA Astrophysics Data System (ADS)

Peng, Xinsheng; Wang, Jingpeng; Thomas, Dan F.; Chen, Aicheng

2005-10-01

A simple and facile method is described to directly synthesize TiO2 nanostructures on titanium substrates by oxidizing Ti foil using small organic molecules as the oxygen source. The effect of reaction temperature and oxygen source on the formation of the TiO2 nanostructures has been studied using scanning electron microscopy, x-ray diffraction, transmission electron microscopy, Raman spectroscopy and water contact angle measurement. Polycrystalline grains are formed when pure oxygen and formic acid are used as the oxygen source; elongated micro-crystals are produced when water vapour is used as the oxygen source; oriented and aligned TiO2 nanorod arrays are synthesized when ethanol, acetaldehyde or acetone are used as the oxygen source. The growth mechanism of the TiO2 nanostructures is discussed. The diffusion of Ti atoms to the oxide/gas interface via the network of the grain boundaries of the thin oxide layer is the determining factor for the formation of well-aligned TiO2 nanorod arrays. The wetting properties of the TiO2 nanostructured surfaces formed are dictated by their structure, varying from a hydrophilic surface to a strongly hydrophobic surface as the surface structure changes from polycrystalline grains to well-aligned nanorod arrays. This tunable growth of TiO2 nanostructures is desirable for promising applications of TiO2 nanostructures in the development of optical devices, sensors, photo-catalysts and self-cleaning coatings.

Ultra-fast microwave-assisted hydrothermal synthesis of long vertically aligned ZnO nanowires for dye-sensitized solar cell application.

PubMed

Mahpeykar, S M; Koohsorkhi, J; Ghafoori-Fard, H

2012-04-27

Long vertically aligned ZnO nanowire arrays were synthesized using an ultra-fast microwave-assisted hydrothermal process. Using this method, we were able to grow ZnO nanowire arrays at an average growth rate as high as 200 nm min(-1) for maximum microwave power level. This method does not suffer from the growth stoppage problem at long growth times that, according to our investigations, a normal microwave-assisted hydrothermal method suffers from. Longitudinal growth of the nanowire arrays was investigated as a function of microwave power level and growth time using cross-sectional FESEM images of the grown arrays. Effect of seed layer on the alignment of nanowires was also studied. X-ray diffraction analysis confirmed c-axis orientation and single-phase wurtzite structure of the nanowires. J-V curves of the fabricated ZnO nanowire-based mercurochrome-sensitized solar cells indicated that the short-circuit current density is increased with increasing the length of the nanowire array. According to the UV-vis spectra of the dyes detached from the cells, these increments were mainly attributed to the enlarged internal surface area and therefore dye loading enhancement in the lengthened nanowire arrays.

Antenna-coupled TES bolometers used in BICEP2, Keck Array, and SPIDER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aikin, R. W.; Amiri, M.

We have developed antenna-coupled transition-edge sensor bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including Bicep2, Keck Array, and the balloon borne Spider. These detectors have reached maturity and this paper reports on their design principles, overall performance, and key challenges associated with design and production. Our detector arrays repeatedly produce spectral bands with 20%–30% bandwidth at 95, 150, or 230 GHz. The integrated antenna arrays synthesize symmetric co-aligned beams with controlled side-lobe levels. Cross-polarized response on boresight is typicallymore » $$\\sim 0.5\\%$$, consistent with cross-talk in our multiplexed readout system. End-to-end optical efficiencies in our cameras are routinely 35% or higher, with per detector sensitivities of NET ~ 300 $$\\mu {{\\rm{K}}}_{\\mathrm{CMB}}\\sqrt{{\\rm{s}}}$$. Thanks to the scalability of this design, we have deployed 2560 detectors as 1280 matched pairs in Keck Array with a combined instantaneous sensitivity of $$\\sim 9\\;\\mu {{\\rm{K}}}_{\\mathrm{CMB}}\\sqrt{{\\rm{s}}}$$, as measured directly from CMB maps in the 2013 season. Furthermore, similar arrays have recently flown in the Spider instrument, and development of this technology is ongoing.« less

Antenna-coupled TES bolometers used in BICEP2, Keck Array, and SPIDER

DOE PAGES

Ade, P. A. R.; Aikin, R. W.; Amiri, M.; ...

2015-10-20

We have developed antenna-coupled transition-edge sensor bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including Bicep2, Keck Array, and the balloon borne Spider. These detectors have reached maturity and this paper reports on their design principles, overall performance, and key challenges associated with design and production. Our detector arrays repeatedly produce spectral bands with 20%–30% bandwidth at 95, 150, or 230 GHz. The integrated antenna arrays synthesize symmetric co-aligned beams with controlled side-lobe levels. Cross-polarized response on boresight is typicallymore » $$\\sim 0.5\\%$$, consistent with cross-talk in our multiplexed readout system. End-to-end optical efficiencies in our cameras are routinely 35% or higher, with per detector sensitivities of NET ~ 300 $$\\mu {{\\rm{K}}}_{\\mathrm{CMB}}\\sqrt{{\\rm{s}}}$$. Thanks to the scalability of this design, we have deployed 2560 detectors as 1280 matched pairs in Keck Array with a combined instantaneous sensitivity of $$\\sim 9\\;\\mu {{\\rm{K}}}_{\\mathrm{CMB}}\\sqrt{{\\rm{s}}}$$, as measured directly from CMB maps in the 2013 season. Furthermore, similar arrays have recently flown in the Spider instrument, and development of this technology is ongoing.« less

Plasmonic nanorod arrays of a two-segment dimer and a coaxial cable with 1 nm gap for large field confinement and enhancement.

PubMed

Cheng, Zi-Qiang; Nan, Fan; Yang, Da-Jie; Zhong, Yu-Ting; Ma, Liang; Hao, Zhong-Hua; Zhou, Li; Wang, Qu-Quan

2015-01-28

Seeking plasmonic nanostructures with large field confinement and enhancement is significant for photonic and electronic nanodevices with high sensitivity, reproducibility, and tunability. Here, we report the synthesis of plasmonic arrays composed of two-segment dimer nanorods and coaxial cable nanorods with ∼1 nm gap insulated by a self-assembled Raman molecule monolayer. The gap-induced plasmon coupling generates an intense field in the gap region of the dimer junction and the cable interlayer. As a result, the longitudinal plasmon resonance of nanorod arrays with high tunability is obviously enhanced. Most interestingly, the field enhancement of dimer nanorod arrays can be tuned by the length ratio L1/L2 of the two segments, and the maximal enhancement appears at L1/L2 = 1. In that case, the two-photon luminescence (TPL) of dimer nanorod arrays and the Raman intensity in the dimer junction is enhanced by 27 and 30 times, respectively, under resonant excitation. In the same way, the Raman intensity in the gap region is enhanced 16 times for the coaxial cable nanorod arrays. The plasmonic nanorod arrays synthesized by the facile method, having tunable plasmon properties and large field enhancement, indicate an attractive pathway to the photonic nanodevices.

Real-time PCR array as a universal platform for the detection of genetically modified crops and its application in identifying unapproved genetically modified crops in Japan.

PubMed

Mano, Junichi; Shigemitsu, Natsuki; Futo, Satoshi; Akiyama, Hiroshi; Teshima, Reiko; Hino, Akihiro; Furui, Satoshi; Kitta, Kazumi

2009-01-14

We developed a novel type of real-time polymerase chain reaction (PCR) array with TaqMan chemistry as a platform for the comprehensive and semiquantitative detection of genetically modified (GM) crops. Thirty primer-probe sets for the specific detection of GM lines, recombinant DNA (r-DNA) segments, endogenous reference genes, and donor organisms were synthesized, and a 96-well PCR plate was prepared with a different primer-probe in each well as the real-time PCR array. The specificity and sensitivity of the array were evaluated. A comparative analysis with the data and publicly available information on GM crops approved in Japan allowed us to assume the possibility of unapproved GM crop contamination. Furthermore, we designed a Microsoft Excel spreadsheet application, Unapproved GMO Checker version 2.01, which helps process all the data of real-time PCR arrays for the easy assumption of unapproved GM crop contamination. The spreadsheet is available free of charge at http://cse.naro.affrc.go.jp/jmano/index.html .

Wafer-Scale Hierarchical Nanopillar Arrays Based on Au Masks and Reactive Ion Etching for Effective 3D SERS Substrate.

PubMed

Men, Dandan; Wu, Yingyi; Wang, Chu; Xiang, Junhuai; Yang, Ganlan; Wan, Changjun; Zhang, Honghua

2018-02-04

Two-dimensional (2D) periodic micro/nanostructured arrays as SERS substrates have attracted intense attention due to their excellent uniformity and good stability. In this work, periodic hierarchical SiO₂ nanopillar arrays decorated with Ag nanoparticles (NPs) with clean surface were prepared on a wafer-scale using monolayer Au NP arrays as masks, followed by reactive ion etching (RIE), depositing Ag layer and annealing. For the prepared SiO₂ nanopillar arrays decorated with Ag NPs, the size of Ag NPs was tuned from ca. 24 to 126 nanometers by controlling the deposition thickness of Ag film. Importantly, the SiO₂ nanopillar arrays decorated with Ag NPs could be used as highly sensitive SERS substrate for the detection of 4-aminothiophenol (4-ATP) and rhodamine 6G (R6G) due to the high loading of Ag NPs and a very uniform morphology. With a deposition thickness of Ag layer of 30 nm, the SiO₂ nanopillar arrays decorated with Ag NPs exhibited the best sensitive SERS activity. The excellent SERS performance of this substrate is mainly attributed to high-density "hotspots" derived from nanogaps between Ag NPs. Furthermore, this strategy might be extended to synthesize other nanostructured arrays with a large area, which are difficult to be prepared only via conventional wet-chemical or physical methods.

Formation of newly synthesized adeno-associated virus capsids in the cell nucleus.

PubMed

Bell, Peter; Vandenberghe, Luk H; Wilson, James M

2014-06-01

Adeno-associated virus (AAV) particles inside the nucleus of a HEK 293 cell are shown by electron microscopy. Cells have been triple-transfected for vector production and were analyzed for capsid formation three days later. Newly assembled particle are visible as seemingly unstructured conglomerates or crystal-like arrays.

Two-Volt Josephson Arbitrary Waveform Synthesizer Using Wilkinson Dividers.

PubMed

Flowers-Jacobs, Nathan E; Fox, Anna E; Dresselhaus, Paul D; Schwall, Robert E; Benz, Samuel P

2016-09-01

The root-mean-square (rms) output voltage of the NIST Josephson arbitrary waveform synthesizer (JAWS) has been doubled from 1 V to a record 2 V by combining two new 1 V chips on a cryocooler. This higher voltage will improve calibrations of ac thermal voltage converters and precision voltage measurements that require state-of-the-art quantum accuracy, stability, and signal-to-noise ratio. We achieved this increase in output voltage by using four on-chip Wilkinson dividers and eight inner-outer dc blocks, which enable biasing of eight Josephson junction (JJ) arrays with high-speed inputs from only four high-speed pulse generator channels. This approach halves the number of pulse generator channels required in future JAWS systems. We also implemented on-chip superconducting interconnects between JJ arrays, which reduces systematic errors and enables a new modular chip package. Finally, we demonstrate a new technique for measuring and visualizing the operating current range that reduces the measurement time by almost two orders of magnitude and reveals the relationship between distortion in the output spectrum and output pulse sequence errors.

Template directed synthesis of plasmonic gold nanotubes with tunable IR absorbance.

PubMed

Bridges, Colin R; Schon, Tyler B; DiCarmine, Paul M; Seferos, Dwight S

2013-04-01

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates, as well as a wide range of other fields such as photo-thermal heating, permselective transport, catalysis, microfluidics, and electrochemical sensing. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening.

Construction of a Quantum Matter Synthesizer

NASA Astrophysics Data System (ADS)

Trisnadi, Jonathan; McDonald, Mickey; Chin, Cheng

2017-04-01

We report progress on the construction of a new platform to manipulate ultracold atoms. The ``Quantum Matter Synthesizer (QMS)'' will have the capability of deterministically preparing large 2D arrays of atoms with single site addressability. Cesium atoms are first transferred into a science cell (specially textured to reduce reflectance to 0.1% across a wide range of wavelengths and incident angles) via a moving 1D lattice, where they are loaded into a magic-wavelength, far-detuned 2D optical lattice. Two NA=0.8 microscope objectives surround the science cell from above and below. The lower objective will be used to project an array of optical tweezers created via a digital micromirror device (DMD) onto the atom-trapping plane, which will be used to rearrange atoms into a desired configuration after first taking a site-resolved fluorescence image of the initial atomic distribution with the upper objective. We provide updates on our magnetic-optical trap and Raman-sideband cooling performance, characterization of the resolution of our microscope objectives, and stability tests for the objective mounting structure.

Fabrication of free-standing aligned multiwalled carbon nanotube array for Li-ion batteries

NASA Astrophysics Data System (ADS)

Bulusheva, L. G.; Arkhipov, V. E.; Fedorovskaya, E. O.; Zhang, Su; Kurenya, A. G.; Kanygin, M. A.; Asanov, I. P.; Tsygankova, A. R.; Chen, Xiaohong; Song, Huaihe; Okotrub, A. V.

2016-04-01

We show that a high-temperature CCl4 vapor treatment of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) grown on silicon substrate allows carefully detach the array from the substrate. Moreover, this procedure partially purifies the VA-MWCNTs from the residual iron catalyst. To improve electrical connectivity of free-standing VA-MWCNTs in an electrochemical cell, the array was placed between the layers of Ni foam. Such assembly demonstrated the better performance in Li-battery as compared to the disordered MWCNTs. After 50 cycles, the specific capacity of VA-MWCNT array synthesized from 0.5 wt% ferrocene solution in toluene was 350 mAh g-1 at a current density of 0.1 A g-1, while the battery with the disordered MWCNTs achieved 197 mAh g-1 only. By the results of electrochemical impedance spectroscopy, the higher capacity of VA-MWCNTs was attributed to larger surface area available for electrolyte and Li ions due to the absence of binder coating.

Digital processing of array seismic recordings

USGS Publications Warehouse

Ryall, Alan; Birtill, John

1962-01-01

This technical letter contains a brief review of the operations which are involved in digital processing of array seismic recordings by the methods of velocity filtering, summation, cross-multiplication and integration, and by combinations of these operations (the "UK Method" and multiple correlation). Examples are presented of analyses by the several techniques on array recordings which were obtained by the U.S. Geological Survey during chemical and nuclear explosions in the western United States. Seismograms are synthesized using actual noise and Pn-signal recordings, such that the signal-to-noise ratio, onset time and velocity of the signal are predetermined for the synthetic record. These records are then analyzed by summation, cross-multiplication, multiple correlation and the UK technique, and the results are compared. For all of the examples presented, analysis by the non-linear techniques of multiple correlation and cross-multiplication of the traces on an array recording are preferred to analyses by the linear operations involved in summation and the UK Method.

An artificial tongue fluorescent sensor array for identification and quantitation of various heavy metal ions.

PubMed

Xu, Wang; Ren, Changliang; Teoh, Chai Lean; Peng, Juanjuan; Gadre, Shubhankar Haribhau; Rhee, Hyun-Woo; Lee, Chi-Lik Ken; Chang, Young-Tae

2014-09-02

Herein, a small-molecule fluorescent sensor array for rapid identification of seven heavy metal ions was designed and synthesized, with its sensing mechanism mimicking that of a tongue. The photoinduced electron transfer and intramolecular charge transfer mechanism result in combinatorial interactions between sensor array and heavy metal ions, which lead to diversified fluorescence wavelength shifts and emission intensity changes. Upon principle component analysis (PCA), this result renders clear identification of each heavy metal ion on a 3D spatial dispersion graph. Further exploration provides a concentration-dependent pattern, allowing both qualitative and quantitative measurements of heavy metal ions. On the basis of this information, a "safe-zone" concept was proposed, which provides rapid exclusion of versatile hazardous species from clean water samples based on toxicity characteristic leaching procedure standards. This type of small-molecule fluorescent sensor array could open a new avenue for multiple heavy metal ion detection and simplified water quality analysis.

Renewable Lignosulfonate-Assisted Synthesis of Hierarchical Nanoflake-Array-Flower ZnO Nanomaterials in Mixed Solvents and Their Photocatalytic Performance

NASA Astrophysics Data System (ADS)

Li, Yue; Zuo, Hong-Fen; Guo, Yuan-Ru; Miao, Ting-Ting; Pan, Qing-Jiang

2016-05-01

With the assistance of sodium lignosulfonate, hierarchical nanoflake-array-flower nanostructure of ZnO has been fabricated by a facile precipitation method in mixed solvents. The sodium lignosulfonate amount used in our synthetic route is able to fine-tune ZnO morphology and an abundance of pores have been observed in the nanoflake-array-flower ZnO, which result in specific surface area reaching as high as 82.9 m2 · g-1. The synthesized ZnO exhibits superior photocatalytic activity even under low-power UV illumination (6 W). It is conjectured that both nanoflake-array structure and plenty of pores embedded in ZnO flakes may provide scaffold microenvironments to enhance photocatalytic activity. Additionally, this catalyst can be used repeatedly without a significant loss in photocatalytic activity. The low-cost, simple synthetic approach as well as high photocatalytic and recycling efficiency of our ZnO nanomaterials allows for application to treat wastewater containing organic pollutants in an effective way.

Fabrication and characterization of hexagonally patterned quasi-1D ZnO nanowire arrays

PubMed Central

2014-01-01

Quasi-one-dimensional (quasi-1D) ZnO nanowire arrays with hexagonal pattern have been successfully synthesized via the vapor transport process without any metal catalyst. By utilizing polystyrene microsphere self-assembled monolayer, sol–gel-derived ZnO thin films were used as the periodic nucleation sites for the growth of ZnO nanowires. High-quality quasi-1D ZnO nanowires were grown from nucleation sites, and the original hexagonal periodicity is well-preserved. According to the experimental results, the vapor transport solid condensation mechanism was proposed, in which the sol–gel-derived ZnO film acting as a seed layer for nucleation. This simple method provides a favorable way to form quasi-1D ZnO nanostructures applicable to diverse fields such as two-dimensional photonic crystal, nanolaser, sensor arrays, and other optoelectronic devices. PMID:24521308

Small nickel nanoparticle arrays from long chain imidazolium ionic liquids

DOE PAGES

Yang, Mei; Campbell, Paul S.; Santini, Catherine C.; ...

2013-11-08

A series of six long chain alkyl mono- and bi-cationic imidazolium based salts with bis(trifluoromethylsulfonyl)imide (NTf 2–) as the anion were synthesized and characterized. Single crystal structure of 1-methyl-3-octadecylimidazolium bis(trifluoromethylsulfonyl)imide could be obtained by X-ray analysis. All these long chain alkyl imidazolium based ILs were applied in the synthesis of nickel nanoparticles via chemical decomposition of an organometallic precursor of nickel. In these media, spontaneous decomposition of Ni(COD) 2 (COD = 1,5-cyclooctadiene) in the absence of H 2 occurred giving small NPs (≤4 nm) with narrow size distributions. Interestingly, formation of regularly interspaced NP arrays was also observed in longmore » chain ILs. Lastly, such array formation could be interesting for potential applications such as carbon nanotube growth.« less

Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms.

PubMed

Pruttivarasin, Thaned; Katori, Hidetoshi

2015-11-01

We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

Silicon nanostructure arrays prepared by single step metal assisted chemical etching from single crystal wafer

NASA Astrophysics Data System (ADS)

Sarkar, Kalyan; Das, Debajyoti

2018-04-01

Arrays of silicon nanostructures have been produced by single step Metal Assisted Chemical Etching (MACE) of single crystal Si-wafers at room temp and normal atmospheric condition. By studying optical and structural properties of the silicon nanowire like structures synthesized by Ag catalyst assisted chemical etching, a significant change in the reflectance spectra has been obtained leading to a gross reduction in reflectance from ˜31% to less than 1%. In comparison with bulk c-Si, the surface areas of the nanostructured samples have been increased significantly with the etching time, leading to an efficient absorption of light, favorable for photovoltaic applications.

A distance-controlled nanoparticle array using PEGylated ferritin

NASA Astrophysics Data System (ADS)

He, Chao; Uenuma, Mutsunori; Okamoto, Naofumi; Kamitake, Hiroki; Ishikawa, Yasuaki; Yamashita, Ichiro; Uraoka, Yukiharu

2014-12-01

A distance-controlled nanoparticle (NP) array was investigated using a simple spin coating process. It was found that the separation distance of NPs was controlled at the nanoscale by using polyethylene glycols (PEGs). Ferritin was used to synthesize NPs and carry them to a substrate by using the different molecular weight of PEGs. In order to control the distance of the NPs, PEGs with molecular weights of 2k, 5k, 10k and 20k were modified on ferritin with 10 mM ion strength and 0.01 mg ml-1 ferritin concentration. The separated distances of NPs increased along with increase in PEG molecular weight.

Competing Liquid Phase Instabilities during Pulsed Laser Induced Self-Assembly of Copper Rings into Ordered Nanoparticle Arrays on SiO 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Y.; Fowlkes, J. D.; Roberts, N. A.

Nanoscale copper rings of different radii, thicknesses, and widths were synthesized on silicon dioxide thin films and were subsequently liquefied via a nanosecond pulse laser treatment. During the nanoscale liquid lifetimes, the rings experience competing retraction dynamics and thin film and/or Rayleigh-Plateau types of instabilities, which lead to arrays of ordered nanodroplets. Surprisingly, the results are significantly different from those of similar experiments carried out on a Si surface.(1) We use hydrodynamic simulations to elucidate how the different liquid/solid interactions control the different instability mechanisms in the present problem.

Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pruttivarasin, Thaned, E-mail: thaned.pruttivarasin@riken.jp; Katori, Hidetoshi; Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656

We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

Opto-VLSI-based photonic true-time delay architecture for broadband adaptive nulling in phased array antennas.

PubMed

Juswardy, Budi; Xiao, Feng; Alameh, Kamal

2009-03-16

This paper proposes a novel Opto-VLSI-based tunable true-time delay generation unit for adaptively steering the nulls of microwave phased array antennas. Arbitrary single or multiple true-time delays can simultaneously be synthesized for each antenna element by slicing an RF-modulated broadband optical source and routing specific sliced wavebands through an Opto-VLSI processor to a high-dispersion fiber. Experimental results are presented, which demonstrate the principle of the true-time delay unit through the generation of 5 arbitrary true-time delays of up to 2.5 ns each. (c) 2009 Optical Society of America

The effects of GaN nanocolumn arrays and thin SixNy buffer layers on the morphology of GaN layers grown by plasma-assisted molecular beam epitaxy on Si(111) substrates

NASA Astrophysics Data System (ADS)

Shubina, K. Yu; Pirogov, E. V.; Mizerov, A. M.; Nikitina, E. V.; Bouravleuv, A. D.

2018-03-01

The effects of GaN nanocolumn arrays and a thin SixNy layer, used as buffer layers, on the morphology of GaN epitaxial layers are investigated. Two types of samples with different buffer layers were synthesized by PA-MBE. The morphology of the samples was characterized by SEM. The crystalline quality of the samples was assessed by XRD. The possibility of synthesis of continuous crystalline GaN layers on Si(111) substrates without the addition of other materials such as aluminum nitride was demonstrated.

Single step synthesis of rutile TiO{sub 2} nanoflower array film by chemical bath deposition method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhandayuthapani, T.; Sivakumar, R.; Ilangovan, R., E-mail: rilangovan@yahoo.com

2016-05-06

Titanium oxide (TiO{sub 2}) nanostructures such as nanorod arrays, nanotube arrays and nanoflower arrays have been extensively investigated by the researchers. Among them nanoflower arrays has shown superior performance than other nanostructures in Dye sensitized solar cell, photocatalysis and energy storage applications. Herein, a single step synthesis for rutile TiO{sub 2} nanoflower array films suitable for device applications has been reported. Rutile TiO{sub 2} nanoflower thin film was synthesized by chemical bath deposition method using NaCl as an additive. Bath temperature induced evolution of nanoflower thin film arrays was observed from the morphological study. X-ray diffraction study confirmed the presencemore » of rutile phase polycrystalline TiO{sub 2}. Micro-Raman study revealed the presence of surface phonon mode at 105 cm{sup −1} due to the phonon confinement effect (finite size effect), in addition with the rutile Raman active modes of B{sub 1}g (143 cm{sup −1}), Eg (442 cm{sup −1}) and A{sub 1}g (607 cm{sup −1}). Further, the FTIR spectrum confirmed the presence of Ti-O-Ti bonding vibration. The Tauc plot showed the direct energy band gap nature of the film with the value of 2.9 eV.« less

Method and apparatus for synthesis of arrays of DNA probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cerrina, Francesco; Sussman, Michael R.; Blattner, Frederick R.

The synthesis of arrays of DNA probes sequences, polypeptides, and the like is carried out using a patterning process on an active surface of a substrate. An image is projected onto the active surface of the substrate utilizing an image former that includes a light source that provides light to a micromirror device comprising an array of electronically addressable micromirrors, each of which can be selectively tilted between one of at least two positions. Projection optics receives the light reflected from the micromirrors along an optical axis and precisely images the micromirrors onto the active surface of the substrate, whichmore » may be used to activate the surface of the substrate. The first level of bases may then be applied to the substrate, followed by development steps, and subsequent exposure of the substrate utilizing a different pattern of micromirrors, with further repeats until the elements of a two dimensional array on the substrate surface have an appropriate base bound thereto. The micromirror array can be controlled in conjunction with a DNA synthesizer supplying appropriate reagents to a flow cell containing the active substrate to control the sequencing of images presented by the micromirror array in coordination of the reagents provided to the substrate.« less

Photoelectrochemical Water Oxidation by GaAs Nanowire Arrays Protected with Atomic Layer Deposited NiO x Electrocatalysts

NASA Astrophysics Data System (ADS)

Zeng, Joy; Xu, Xiaoqing; Parameshwaran, Vijay; Baker, Jon; Bent, Stacey; Wong, H.-S. Philip; Clemens, Bruce

2018-02-01

Photoelectrochemical (PEC) hydrogen production makes possible the direct conversion of solar energy into chemical fuel. In this work, PEC photoanodes consisting of GaAs nanowire (NW) arrays were fabricated, characterized, and then demonstrated for the oxygen evolution reaction (OER). Uniform and periodic GaAs nanowire arrays were grown on a heavily n-doped GaAs substrates by metal-organic chemical vapor deposition selective area growth. The nanowire arrays were characterized using cyclic voltammetry and impedance spectroscopy in a non-aqueous electrochemical system using ferrocene/ferrocenium (Fc/Fc+) as a redox couple, and a maximum oxidation photocurrent of 11.1 mA/cm2 was measured. GaAs NW arrays with a 36 nm layer of nickel oxide (NiO x ) synthesized by atomic layer deposition were then used as photoanodes to drive the OER. In addition to acting as an electrocatalyst, the NiO x layer served to protect the GaAs NWs from oxidative corrosion. Using this strategy, GaAs NW photoanodes were successfully used for the oxygen evolution reaction. This is the first demonstration of GaAs NW arrays for effective OER, and the fabrication and protection strategy developed in this work can be extended to study any other nanostructured semiconductor materials systems for electrochemical solar energy conversion.

Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nam, Chang-Yong, E-mail: cynam@bnl.gov; Stein, Aaron; Kisslinger, Kim

We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼10{sup 19 }cm{sup −3} carrier density, and ∼0.1 cm{sup 2} V{sup −1} s{sup −1} electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate themore » potential application of infiltration synthesis in fabricating metal oxide electronic devices.« less

Titanium(IV) isopropoxide mediated solution phase reductive amination on an automated platform: application in the generation of urea and amide libraries.

PubMed

Bhattacharyya, S; Fan, L; Vo, L; Labadie, J

2000-04-01

Amine libraries and their derivatives are important targets for high throughput synthesis because of their versatility as medicinal agents and agrochemicals. As a part of our efforts towards automated chemical library synthesis, a titanium(IV) isopropoxide mediated solution phase reductive amination protocol was successfully translated to automation on the Trident(TM) library synthesizer of Argonaut Technologies. An array of 24 secondary amines was prepared in high yield and purity from 4 primary amines and 6 carbonyl compounds. These secondary amines were further utilized in a split synthesis to generate libraries of ureas, amides and sulfonamides in solution phase on the Trident(TM). The automated runs included 192 reactions to synthesize 96 ureas in duplicate and 96 reactions to synthesize 48 amides and 48 sulfonamides. A number of polymer-assisted solution phase protocols were employed for parallel work-up and purification of the products in each step.

Fabrication of Metallic Quantum Dot Arrays For Nanoscale Nonlinear Optics

NASA Astrophysics Data System (ADS)

McMahon, M. D.; Hmelo, A. B.; Lopez Magruder, R., III; Weller Haglund, R. A., Jr.; Feldman, L. C.

2003-03-01

Ordered arrays of metal nanocrystals embedded in or sequestered on dielectric hosts have potential applications as elements of nonlinear or near-field optical circuits, as sensitizers for fluorescence emitters and photo detectors, and as anchor points for arrays of biological molecules. Metal nanocrystals are strongly confined electronic systems with size-, shape and spatial orientation-dependent optical responses. At the smallest scales (below about 15 nm diameter), their band structure is drastically altered by the small size of the system, and the reduced population of conduction-band electrons. Here we report on the fabrication of two-dimensional ordered metallic nanocrystal arrays, and one-dimensional nanocrystal-loaded waveguides for optical investigations. We have employed strategies for synthesizing metal nanocrystal composites that capitalize on the best features of focused ion beam (FIB) machining and pulsed laser deposition (PLD). The FIB generates arrays of specialized sites; PLD vapor deposition results in the directed self-assembly of Ag nanoparticles nucleated at the FIB generated sites on silicon substrates. We present results based on the SEM, AFM and optical characterization of prototype composites. This research has been supported by the U.S. Department of Energy under grant DE-FG02-01ER45916.

Hierarchical NiCo2 S4 Nanotube@NiCo2 S4 Nanosheet Arrays on Ni Foam for High-Performance Supercapacitors.

PubMed

Chen, Haichao; Chen, Si; Shao, Hongyan; Li, Chao; Fan, Meiqiang; Chen, Da; Tian, Guanglei; Shu, Kangying

2016-01-01

Hierarchical NiCo2 S4 nanotube@NiCo2 S4 nanosheet arrays on Ni foam have been successfully synthesized. Owing to the unique hierarchical structure, enhanced capacitive performance can be attained. A specific capacitance up to 4.38 F cm(-2) is attained at 5 mA cm(-2) , which is much higher than the specific capacitance values of NiCo2 O4 nanosheet arrays, NiCo2 S4 nanosheet arrays and NiCo2 S4 nanotube arrays on Ni foam. The hierarchical NiCo2 S4 nanostructure shows superior cycling stability; after 5000 cycles, the specific capacitance still maintains 3.5 F cm(-2) . In addition, through the morphology and crystal structure measurement after cycling stability test, it is found that the NiCo2 S4 electroactive materials are gradually corroded; however, the NiCo2 S4 phase can still be well-maintained. Our results show that hierarchical NiCo2 S4 nanostructures are suitable electroactive materials for high performance supercapacitors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ZnO/Er2O3 core-shell nanorod arrays: Synthesis, properties and growth mechanism

NASA Astrophysics Data System (ADS)

Yang, Jun; Wang, Yongqian; Jiang, Tingting; Li, Yinchang; Yang, Xiande

2015-01-01

In this study, we demonstrated large-scale ZnO/Er2O3 core-shell nanorod arrays, which were successfully synthesized by a facile and simple electrodeposition method. The effect of varying the amount of Er2O3 in the range from 0.2 g to 1.0 g on morphology of ZnO nanorod arrays has been thoroughly investigated. The results indicate that the growth pattern of all the ZnO/Er2O3 shell-core nanorod arrays were along c-axis and perpendicular to the substrate as before, even more vertical. Photoluminescence measurement was carried out and the PL peaks at 382 nm, 438 nm and 462 nm were observed, which are considered to be due to free excitons and donor-bound excitons, respectively. The ZnO/Er2O3 core-shell nanorods exhibited improved optical property, which can be attributed to the enhanced donor density by the covered Er2O3. Finally, a possible growth mechanism of the ZnO nanostructures is discussed. The electrochemical deposition of ZnO/Er2O3 core-shell nanorod arrays including two stages, namely nucleation and growth process.

Ultraviolet-assisted direct patterning and low-temperature formation of flexible ZrO2 resistive switching arrays on PET/ITO substrates

NASA Astrophysics Data System (ADS)

Li, Lingwei; Chen, Yuanqing; Yin, Xiaoru; Song, Yang; Li, Na; Niu, Jinfen; Wu, Huimin; Qu, Wenwen

2017-12-01

We demonstrate a low-cost and facile photochemical solution method to prepare the ZrO2 resistive switching arrays as memristive units on flexible PET/ITO substrates. ZrO2 solution sensitive to UV light of 337 nm was synthesized using zirconium n-butyl alcohol as the precursor, and benzoylacetone as the complexing agent. After the dip-coated ZrO2 gel films were irradiated through a mask under the UV lamp (with wavelength of 325-365 nm) at room temperature and rinsed in ethanol, the ZrO2 gel arrays were obtained on PET/ITO substrates. Subsequently, the ZrO2 gel arrays were irradiated by deep UV light of 254 and 185 nm at 150 °C, resulting in the amorphous ZrO2 memristive micro-arrays. The ZrO2 units on flexible PET/ITO substrates exhibited excellent memristive properties. A high ratio of 104 of on-state and off-state resistance was obtained. The resistive switching behavior of the flexible device remained stable after being bent for 103 times. The device showed stable flexibility up to a minimum bending diameter of 1.25 cm.

Maskless writing of a flexible nanoscale transistor with Au-contacted carbon nanotube electrodes

NASA Astrophysics Data System (ADS)

Dockendorf, Cedric P. R.; Poulikakos, Dimos; Hwang, Gilgueng; Nelson, Bradley J.; Grigoropoulos, Costas P.

2007-12-01

A flexible polymer field effect transistor with a nanoscale carbon nanotube channel is conceptualized and realized herein. Carbon nanotubes (CNTs) were dispersed on a polyimide substrate and marked in an scanning electron microscope with focused ion beam such that they could be contacted with gold nanoink. The CNTs were divided into two parts forming the source and drain of the transistor. A micropipette writing method was used to contact the carbon nanotube electrodes with gold nanoink and to deposit the poly(3-hexylthiophene) as an active layer. The mobility of the transistors is of the order of 10-5cm/Vs. After fabrication, the flexible transistors can be peeled off the substrate.

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Fukutake, Naoyuki; Miyoshi, Nozomi; Takasawa, Yuya; Urakawa, Tatsuya; Gowa, Tomoko; Okamoto, Kazumasa; Oshima, Akihiro; Tagawa, Seiichi; Washio, Masakazu

2010-06-01

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 µm and 90 nm, respectively. Their aspect ratio was about 17.

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Naoyuki Fukutake,; Nozomi Miyoshi,; Yuya Takasawa,; Tatsuya Urakawa,; Tomoko Gowa,; Kazumasa Okamoto,; Akihiro Oshima,; Seiichi Tagawa,; Masakazu Washio,

2010-06-01

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 μm and 90 nm, respectively. Their aspect ratio was about 17.

Fabrication of the planar angular rotator using the CMOS process

NASA Astrophysics Data System (ADS)

Dai, Ching-Liang; Chang, Chien-Liu; Chen, Hung-Lin; Chang, Pei-Zen

2002-05-01

In this investigation we propose a novel planar angular rotator fabricated by the conventional complementary metal-oxide semiconductor (CMOS) process. Following the 0.6 μm single poly triple metal (SPTM) CMOS process, the device is completed by a simple maskless, post-process etching step. The rotor of the planar angular rotator rotates around its geometric center with electrostatic actuation. The proposed design adopts an intelligent mechanism including the slider-crank system to permit simultaneous motion. The CMOS planar angular rotator could be driven with driving voltages of around 40 V. The design proposed here has a shorter response time and longer life, without problems of friction and wear, compared to the more common planar angular micromotor.

A simple and cost-effective molecular diagnostic system and DNA probes synthesized by light emitting diode photolithography

NASA Astrophysics Data System (ADS)

Oleksandrov, Sergiy; Kwon, Jung Ho; Lee, Ki-chang; Sujin-Ku; Paek, Mun Cheol

2014-09-01

This work introduces a novel chip to be used in the future as a simple and cost-effective method for creating DNA arrays using light emission diode (LED) photolithography. The DNA chip platform contains 24 independent reaction sites, which allows for the testing of a corresponding amount of patients' samples in hospital. An array of commercial UV LEDs and lens systems was combined with a microfluidic flow system to provide patterning of 24 individual reaction sites, each with 64 independent probes. Using the LED array instead of conventional laser exposure systems or micro-mirror systems significantly reduces the cost of equipment. The microfluidic system together with microfluidic flow cells drastically reduces the amount of used reagents, which is important due to the high cost of commercial reagents. The DNA synthesis efficiency was verified by fluorescence labeling and conventional hybridization.

Hierarchical Nanocomposites of Polyaniline Nanowire Arrays on Reduced Graphene Oxide Sheets for Supercapacitors

PubMed Central

Wang, Li; Ye, Yinjian; Lu, Xingping; Wen, Zhubiao; Li, Zhuang; Hou, Haoqing; Song, Yonghai

2013-01-01

Here we reported a novel route to synthesize a hierarchical nanocomposite (PANI-frGO) of polyaniline (PANI) nanowire arrays covalently bonded on reduced graphene oxide (rGO). In this strategy, nitrophenyl groups were initially grafted on rGO via C-C bond, and then reduced to aminophenyl to act as anchor sites for the growth of PANI arrays on rGO. The functionalized process was confirmed by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The electrochemical properties of the PANI-frGO as supercapacitor materials were investigated. The PANI-frGO nanocomposites showed high capacitance of 590 F g−1 at 0.1 A g−1, and had no loss of capacitance after 200 cycles at 2 A g−1. The improved electrochemical performance suggests promising application of the PANI-frGO nanocomposites in high-performance supercapacitors. PMID:24356535

Enhanced photoelectrochemical property of ZnO nanorods array synthesized on reduced graphene oxide for self-powered biosensing application.

PubMed

Kang, Zhuo; Gu, Yousong; Yan, Xiaoqin; Bai, Zhiming; Liu, Yichong; Liu, Shuo; Zhang, Xiaohui; Zhang, Zheng; Zhang, Xueji; Zhang, Yue

2015-02-15

We have realized the direct synthesis of ZnO nanorods (ZnO NRs) array on reduced graphene layer (rGO), and demonstrated the enhanced photoelectrochemical (PEC) property of the rGO/ZnO based photoanode under UV irradiation compared with the pristine ZnO NRs array. The introduction of the rGO layer resulted in a favorable energy band structure for electron migration, which finally led to the efficient photoinduced charge separation. Such nanostructure was subsequently employed for self-powered PEC biosensing of glutathione in the condition of 0 V bias, with a linear range from 10 to 200 µM, a detection limit of 2.17 µM, as well as excellent selectivity, reproducibility and stability. The results indicated the rGO/ZnO nanostructure is a competitive candidate in the PEC biosensing field. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental vibroacoustic testing of plane panels using synthesized random pressure fields.

PubMed

Robin, Olivier; Berry, Alain; Moreau, Stéphane

2014-06-01

The experimental reproduction of random pressure fields on a plane panel and corresponding induced vibrations is studied. An open-loop reproduction strategy is proposed that uses the synthetic array concept, for which a small array element is moved to create a large array by post-processing. Three possible approaches are suggested to define the complex amplitudes to be imposed to the reproduction sources distributed on a virtual plane facing the panel to be tested. Using a single acoustic monopole, a scanning laser vibrometer and a baffled simply supported aluminum panel, experimental vibroacoustic indicators such as the Transmission Loss for Diffuse Acoustic Field, high-speed subsonic and supersonic Turbulent Boundary Layer excitations are obtained. Comparisons with simulation results obtained using a commercial software show that the Transmission Loss estimation is possible under both excitations. Moreover and as a complement to frequency domain indicators, the vibroacoustic behavior of the panel can be studied in the wave number domain.

Hierarchical Nanocomposites of Polyaniline Nanowire Arrays on Reduced Graphene Oxide Sheets for Supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Li; Ye, Yinjian; Lu, Xingping; Wen, Zhubiao; Li, Zhuang; Hou, Haoqing; Song, Yonghai

2013-12-01

Here we reported a novel route to synthesize a hierarchical nanocomposite (PANI-frGO) of polyaniline (PANI) nanowire arrays covalently bonded on reduced graphene oxide (rGO). In this strategy, nitrophenyl groups were initially grafted on rGO via C-C bond, and then reduced to aminophenyl to act as anchor sites for the growth of PANI arrays on rGO. The functionalized process was confirmed by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The electrochemical properties of the PANI-frGO as supercapacitor materials were investigated. The PANI-frGO nanocomposites showed high capacitance of 590 F g-1 at 0.1 A g-1, and had no loss of capacitance after 200 cycles at 2 A g-1. The improved electrochemical performance suggests promising application of the PANI-frGO nanocomposites in high-performance supercapacitors.

Hierarchical nanocomposites of polyaniline nanowire arrays on reduced graphene oxide sheets for supercapacitors.

PubMed

Wang, Li; Ye, Yinjian; Lu, Xingping; Wen, Zhubiao; Li, Zhuang; Hou, Haoqing; Song, Yonghai

2013-12-20

Here we reported a novel route to synthesize a hierarchical nanocomposite (PANI-frGO) of polyaniline (PANI) nanowire arrays covalently bonded on reduced graphene oxide (rGO). In this strategy, nitrophenyl groups were initially grafted on rGO via C-C bond, and then reduced to aminophenyl to act as anchor sites for the growth of PANI arrays on rGO. The functionalized process was confirmed by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The electrochemical properties of the PANI-frGO as supercapacitor materials were investigated. The PANI-frGO nanocomposites showed high capacitance of 590 F g(-1) at 0.1 A g(-1), and had no loss of capacitance after 200 cycles at 2 A g(-1). The improved electrochemical performance suggests promising application of the PANI-frGO nanocomposites in high-performance supercapacitors.

An Undergraduate Laboratory Exercise to Study the Effect of Darkness on Plant Gene Expression Using DNA Microarray

ERIC Educational Resources Information Center

Chang, Ming-Mei; Briggs, George M.

2007-01-01

DNA microarrays are microscopic arrays on a solid surface, typically a glass slide, on which DNA oligonucleotides are deposited or synthesized in a high-density matrix with a predetermined spatial order. Several types of DNA microarrays have been developed and used for various biological studies. Here, we developed an undergraduate laboratory…

Top-Down Chemoenzymatic Approach to Synthesizing Diverse High-Mannose N-Glycans and Related Neoglycoproteins for Carbohydrate Microarray Analysis.

PubMed

Toonstra, Christian; Wu, Lisa; Li, Chao; Wang, Denong; Wang, Lai-Xi

2018-05-22

High-mannose-type N-glycans are an important component of neutralizing epitopes on HIV-1 envelope glycoprotein gp120. They also serve as signals for protein folding, trafficking, and degradation in protein quality control. A number of lectins and antibodies recognize high-mannose-type N-glycans, and glycan array technology has provided an avenue to probe these oligomannose-specific proteins. We describe in this paper a top-down chemoenzymatic approach to synthesize a library of high-mannose N-glycans and related neoglycoproteins for glycan microarray analysis. The method involves the sequential enzymatic trimming of two readily available natural N-glycans, the Man 9 GlcNAc 2 Asn prepared from soybean flour and the sialoglycopeptide (SGP) isolated from chicken egg yolks, coupled with chromatographic separation to obtain a collection of a full range of natural high-mannose N-glycans. The Asn-linked N-glycans were conjugated to bovine serum albumin (BSA) to provide neoglycoproteins containing the oligomannose moieties. The glycoepitopes displayed were characterized using an array of glycan-binding proteins, including the broadly virus-neutralizing agents, glycan-specific antibody 2G12, Galanthus nivalis lectin (GNA), and Narcissus pseudonarcissus lectin (NPA).

Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

2011-05-01

Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g-1 at 1 A g-1, which remained at 543 F g-1 when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg-1) was maintained even at a high power density of 6000 W kg-1. An excellent long cycle life of the electrode was observed with a retention of ~86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO2 nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications.

Synthesis of NiMn-LDH Nanosheet@Ni3S2 Nanorod Hybrid Structures for Supercapacitor Electrode Materials with Ultrahigh Specific Capacitance.

PubMed

Yu, Shuai; Zhang, Yingxi; Lou, Gaobo; Wu, Yatao; Zhu, Xinqiang; Chen, Hao; Shen, Zhehong; Fu, Shenyuan; Bao, Binfu; Wu, Limin

2018-03-27

One of the key challenges for pseudocapacitive electrode materials with highly effective capacitance output and future practical applications is how to rationally construct hierarchical and ordered hybrid nanoarchitecture through the simple process. Herein, we design and synthesize a novel NiMn-layered double hydroxide nanosheet@Ni 3 S 2 nanorod hybrid array supported on porous nickel foam via a one-pot hydrothermal method. Benefited from the ultrathin and rough nature, the well-defined porous structure of the hybrid array, as well as the synergetic effect between NiMn-layered double hydroxide nanosheets and Ni 3 S 2 nanorods, the as-fabricated hybrid array-based electrode exhibits an ultrahigh specific capacitance of 2703 F g -1 at 3 A g -1 . Moreover, the asymmetric supercapacitor with this hybrid array as a positive electrode and wood-derived activated carbon as a negative electrode demonstrates high energy density (57 Wh Kg -1 at 738 W Kg -1 ) and very good electrochemical cycling stability.

Substrate morphology induced self-organization into carbon nanotube arrays, ropes, and agglomerates.

PubMed

Huang, Jia-Qi; Zhang, Qiang; Xu, Guang-Hui; Qian, Wei-Zhong; Wei, Fei

2008-10-29

In this paper, hydrophobic carbon nanotube (CNT) arrays, ropes, and agglomerates were synthesized through self-organization on quartz substrates with different micro-structures under the same growth condition. On a flat substrate, a uniform woven structure was formed which resulted in a synchronous growth into an array. When the substrate with 10 µm round concaves distributed on the surface was adopted, the woven structure was sporadic and a CNT cluster was grown in the concave. With further growth, CNT ropes were self-organized. Subsequently, when the substrate consisting of irregular ∼100 nm gaps was used, the initial woven structure was high density, thus resulting in the formation of CNT agglomerates. Study results showed that CNT arrays grown on the flat substrate were of the highest purity and had a contact angle of 153.8 ± 0.9°. Thus, the self-organization behavior among CNTs was in situ modulated by different substrate morphology without further treatments. This provides us with an additional understanding of the self-organization of CNTs during growth, as well as strategies for the controllable synthesis of CNTs with fixed properties.

Synthesis and characterization of barium silicide (BaSi2) nanowire arrays for potential solar applications.

PubMed

Pokhrel, Ankit; Samad, Leith; Meng, Fei; Jin, Song

2015-11-07

In order to utilize nanostructured materials for potential solar and other energy-harvesting applications, scalable synthetic techniques for these materials must be developed. Herein we use a vapor phase conversion approach to synthesize nanowire (NW) arrays of semiconducting barium silicide (BaSi2) in high yield for the first time for potential solar applications. Dense arrays of silicon NWs obtained by metal-assisted chemical etching were converted to single-crystalline BaSi2 NW arrays by reacting with Ba vapor at about 930 °C. Structural characterization by X-ray diffraction and high-resolution transmission electron microscopy confirm that the converted NWs are single-crystalline BaSi2. The optimal conversion reaction conditions allow the phase-pure synthesis of BaSi2 NWs that maintain the original NW morphology, and tuning the reaction parameters led to a controllable synthesis of BaSi2 films on silicon substrates. The optical bandgap and electrochemical measurements of these BaSi2 NWs reveal a bandgap and carrier concentrations comparable to previously reported values for BaSi2 thin films.

Thermal Conduction in Vertically Aligned Copper Nanowire Arrays and Composites.

PubMed

Barako, Michael T; Roy-Panzer, Shilpi; English, Timothy S; Kodama, Takashi; Asheghi, Mehdi; Kenny, Thomas W; Goodson, Kenneth E

2015-09-02

The ability to efficiently and reliably transfer heat between sources and sinks is often a bottleneck in the thermal management of modern energy conversion technologies ranging from microelectronics to thermoelectric power generation. These interfaces contribute parasitic thermal resistances that reduce device performance and are subjected to thermomechanical stresses that degrade device lifetime. Dense arrays of vertically aligned metal nanowires (NWs) offer the unique combination of thermal conductance from the constituent metal and mechanical compliance from the high aspect ratio geometry to increase interfacial heat transfer and device reliability. In the present work, we synthesize copper NW arrays directly onto substrates via templated electrodeposition and extend this technique through the use of a sacrificial overplating layer to achieve improved uniformity. Furthermore, we infiltrate the array with an organic phase change material and demonstrate the preservation of thermal properties. We use the 3ω method to measure the axial thermal conductivity of freestanding copper NW arrays to be as high as 70 W m(-1) K(-1), which is more than an order of magnitude larger than most commercial interface materials and enhanced-conductivity nanocomposites reported in the literature. These arrays are highly anisotropic, and the lateral thermal conductivity is found to be only 1-2 W m(-1) K(-1). We use these measured properties to elucidate the governing array-scale transport mechanisms, which include the effects of morphology and energy carrier scattering from size effects and grain boundaries.

Ultra-thin g-C{sub 3}N{sub 4} nanosheets wrapped silicon nanowire array for improved chemical stability and enhanced photoresponse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Beibei; Yu, Hongtao; Quan, Xie, E-mail: quanxie@dlut.edu.cn

2014-11-15

Highlights: • g-C{sub 3}N{sub 4}, as an oxygen free and metal free protective material for Si, was proposed. • g-C{sub 3}N{sub 4} nanosheets wrapped Si nanowire array was synthesized. • SiNW/g-C{sub 3}N{sub 4} exhibited enhancement of photoelectrochemical stability and photocurrent. - Abstract: In order to inhibit the oxidation of Si materials in aqueous solution, Si nanowire array was wrapped by ultra-thin g-C{sub 3}N{sub 4} nanosheets via an electrophoresis process. Scanning electron microscopy and transmission electron microscopy images showed that g-C{sub 3}N{sub 4} nanosheets were evenly distributed on the surface of Si nanowire array. X-ray diffraction patterns indicated that Si nanowiremore » array/g-C{sub 3}N{sub 4} nanosheets were composed of Si (4 0 0 crystal plane) and g-C{sub 3}N{sub 4} (0 0 2 and 1 0 0 crystal planes). The cyclic voltammetry curves revealed that the corrosion of Si nanowire array was restrained under the protection of g-C{sub 3}N{sub 4} nanosheets. Furthermore, the photocurrent density of Si nanowire array/g-C{sub 3}N{sub 4} nanosheets increased by nearly 3 times compared to that of bare Si nanowire array due to the effective charge separation caused by the built-in electric field at the interface. This work will facilitate the applications of Si materials in aqueous solution, such as solar energy harvest and photocatalytic pollution control.« less

Hydrothermally formed three-dimensional hexagon-like P doped Ni(OH)2 rod arrays for high performance all-solid-state asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Li, Kunzhen; Li, Shikuo; Huang, Fangzhi; Lu, Yan; Wang, Lei; Chen, Hong; Zhang, Hui

2018-01-01

Three dimensional hexagon-like phosphrous (P) doped Ni(OH)2 rod arrays grown on Ni foam (NF) are fabricated by a facile and green one-step hydrothermal process. Ni foam is only reacted in a certain concentration of P containing H2O2 aqueous solution. The possible growth mechanism of the P doped Ni(OH)2 rod arrays is discussed. As a battery-type electrode material in situ formed on Ni foam, the binder-free P doped Ni(OH)2 rod arrays electrode displays a ultrahigh specific areal capacitance of 2.11C cm-2 (3.51 F cm-2) at 2 mA cm-2, and excellent cycling stability (95.5% capacitance retention after 7500 cycles). The assembled all-solid-state asymmetric supercapacitor (AAS) based on such P doped Ni(OH)2 rod arrays as the positive electrode and activated carbon as the negative electrode achieves an energy density of 81.3 Wh kg-1 at the power density of 635 W kg-1. The AAS device also exhibits excellent practical performance, which can easily drive an electric fan (3 W rated power) when two AAS devices are assembled in series. Thus, our synthesized P doped Ni(OH)2 rod arrays has a lot of potential applications in future energy storage prospects.

In situ fabrication of Ni-Co (oxy)hydroxide nanowire-supported nanoflake arrays and their application in supercapacitors.

PubMed

Zheng, Xiaoyu; Quan, Honglin; Li, Xiaoxin; He, Hai; Ye, Qinglan; Xu, Xuetang; Wang, Fan

2016-09-29

Three-dimensional (3D) hybrid nanostructured arrays grown on a flexible substrate have recently attracted great attention owing to their potential application as supercapacitor electrodes in portable and wearable electronic devices. Here, we report an in situ conversion of Ni-Co active electrode materials for the fabrication of high-performance electrodes. Ni-Co carbonate hydroxide nanowire arrays on carbon cloth were initially synthesized via a hydrothermal method, and they were gradually converted to Ni-Co (oxy)hydroxide nanowire-supported nanoflake arrays after soaking in an alkaline solution. The evolution of the supercapacitor performance of the soaked electrode was investigated in detail. The areal capacitance increases from 281 mF cm -2 at 1 mA cm -2 to 3710 and 3900 mF cm -2 after soaking for 36 h and 48 h, respectively. More interestingly, the electrode also shows an increased capacitance with charge/discharge cycles due to the long-time soaking in KOH solution, suggesting novel cycling durability. The enhancement in capacitive performance should be related to the formation of a unique nanowire-supported nanoflake array architecture, which controls the agglomeration of nanoflakes, making them fully activated. As a result, the facile in situ fabrication of the hybrid architectural design in this study provides a new approach to fabricate high-performance Ni/Co based hydroxide nanostructure arrays for next-generation energy storage devices.

Supramolecular Control over the Interparticle Distance in Gold Nanoparticle Arrays by Cyclodextrin Polyrotaxanes

PubMed Central

Paulo Coelho, Joao; Osío Barcina, José; Aicart, Emilio; Tardajos, Gloria; Cruz-Gil, Pablo; Salgado, Cástor; Díaz-Núñez, Pablo

2018-01-01

Amphiphilic nonionic ligands, synthesized with a fixed hydrophobic moiety formed by a thiolated alkyl chain and an aromatic ring, and with a hydrophilic tail composed of a variable number of oxyethylene units, were used to functionalize spherical gold nanoparticles (AuNPs) in water. Steady-state and time-resolved fluorescence measurements of the AuNPs in the presence of α-cyclodextrin (α-CD) revealed the formation of supramolecular complexes between the ligand and macrocycle at the surface of the nanocrystals. The addition of α-CD induced the formation of inclusion complexes with a high apparent binding constant that decreased with the increasing oxyethylene chain length. The formation of polyrotaxanes at the surface of AuNPs, in which many α-CDs are trapped as hosts on the long and linear ligands, was demonstrated by the formation of large and homogeneous arrays of self-assembled AuNPs with hexagonal close packing, where the interparticle distance increased with the length of the oxyethylene chain. The estimated number of α-CDs per polyrotaxane suggests a high rigidization of the ligand upon complexation, allowing for nearly perfect control of the interparticle distance in the arrays. This degree of supramolecular control was extended to arrays formed by AuNPs stabilized with polyethylene glycol and even to binary arrays. Electromagnetic simulations showed that the enhancement and distribution of the electric field can be finely controlled in these plasmonic arrays. PMID:29547539

Correlation of lattice defects and thermal processing in the crystallization of titania nanotube arrays

NASA Astrophysics Data System (ADS)

Hosseinpour, Pegah M.; Yung, Daniel; Panaitescu, Eugen; Heiman, Don; Menon, Latika; Budil, David; Lewis, Laura H.

2014-12-01

Titania nanotubes have the potential to be employed in a wide range of energy-related applications such as solar energy-harvesting devices and hydrogen production. As the functionality of titania nanostructures is critically affected by their morphology and crystallinity, it is necessary to understand and control these factors in order to engineer useful materials for green applications. In this study, electrochemically-synthesized titania nanotube arrays were thermally processed in inert and reducing environments to isolate the role of post-synthesis processing conditions on the crystallization behavior, electronic structure and morphology development in titania nanotubes, correlated with the nanotube functionality. Structural and calorimetric studies revealed that as-synthesized amorphous nanotubes crystallize to form the anatase structure in a three-stage process that is facilitated by the creation of structural defects. It is concluded that processing in a reducing gas atmosphere versus in an inert environment provides a larger unit cell volume and a higher concentration of Ti3+ associated with oxygen vacancies, thereby reducing the activation energy of crystallization. Further, post-synthesis annealing in either reducing or inert atmospheres produces pronounced morphological changes, confirming that the nanotube arrays thermally transform into a porous morphology consisting of a fragmented tubular architecture surrounded by a network of connected nanoparticles. This study links explicit data concerning morphology, crystallization and defects, and shows that the annealing gas environment determines the details of the crystal structure, the electronic structure and the morphology of titania nanotubes. These factors, in turn, impact the charge transport and consequently the functionality of these nanotubes as photocatalysts.

Two-dimensional parallel array technology as a new approach to automated combinatorial solid-phase organic synthesis

PubMed

Brennan; Biddison; Frauendorf; Schwarcz; Keen; Ecker; Davis; Tinder; Swayze

1998-01-01

An automated, 96-well parallel array synthesizer for solid-phase organic synthesis has been designed and constructed. The instrument employs a unique reagent array delivery format, in which each reagent utilized has a dedicated plumbing system. An inert atmosphere is maintained during all phases of a synthesis, and temperature can be controlled via a thermal transfer plate which holds the injection molded reaction block. The reaction plate assembly slides in the X-axis direction, while eight nozzle blocks holding the reagent lines slide in the Y-axis direction, allowing for the extremely rapid delivery of any of 64 reagents to 96 wells. In addition, there are six banks of fixed nozzle blocks, which deliver the same reagent or solvent to eight wells at once, for a total of 72 possible reagents. The instrument is controlled by software which allows the straightforward programming of the synthesis of a larger number of compounds. This is accomplished by supplying a general synthetic procedure in the form of a command file, which calls upon certain reagents to be added to specific wells via lookup in a sequence file. The bottle position, flow rate, and concentration of each reagent is stored in a separate reagent table file. To demonstrate the utility of the parallel array synthesizer, a small combinatorial library of hydroxamic acids was prepared in high throughput mode for biological screening. Approximately 1300 compounds were prepared on a 10 μmole scale (3-5 mg) in a few weeks. The resulting crude compounds were generally >80% pure, and were utilized directly for high throughput screening in antibacterial assays. Several active wells were found, and the activity was verified by solution-phase synthesis of analytically pure material, indicating that the system described herein is an efficient means for the parallel synthesis of compounds for lead discovery. Copyright 1998 John Wiley & Sons, Inc.

Nanogrid rolling circle DNA sequencing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Church, George M.; Porreca, Gregory J.; Shendure, Jay

The present invention relates to methods for sequencing a polynucleotide immobilized on an array having a plurality of specific regions each having a defined diameter size, including synthesizing a concatemer of a polynucleotide by rolling circle amplification, wherein the concatemer has a cross-sectional diameter greater than the diameter of a specific region, immobilizing the concatemer to the specific region to make an immobilized concatemer, and sequencing the immobilized concatemer.

Glyco-Immune Diagnostic Signatures and Therapeutic Targets of Mesothelioma

DTIC Science & Technology

2015-09-01

Immunoprofiles; Robotic Arrayer 16. SECURITY CLASSIFICATION OF: U 17. LIMITATION OF ABSTRACT: UU 18. NUMBER OF PAGES 19 19a. NAME OF RESPONSIBLE...General Comments: This project involved novel technology in which biochemically synthesized glycans were robotically printed on glass slides...glycans and the platform was known as the PGA-400. (Figure 1) A standard robotic technology for printing a large range of aminefunctionalized

1D Ni-Co oxide and sulfide nanoarray/carbon aerogel hybrid nanostructures for asymmetric supercapacitors with high energy density and excellent cycling stability.

PubMed

Hao, Pin; Tian, Jian; Sang, Yuanhua; Tuan, Chia-Chi; Cui, Guanwei; Shi, Xifeng; Wong, C P; Tang, Bo; Liu, Hong

2016-09-15

The fabrication of supercapacitor electrodes with high energy density and excellent cycling stability is still a great challenge. A carbon aerogel, possessing a hierarchical porous structure, high specific surface area and electrical conductivity, is an ideal backbone to support transition metal oxides and bring hope to prepare electrodes with high energy density and excellent cycling stability. Therefore, NiCo 2 S 4 nanotube array/carbon aerogel and NiCo 2 O 4 nanoneedle array/carbon aerogel hybrid supercapacitor electrode materials were synthesized by assembling Ni-Co precursor needle arrays on the surface of the channel walls of hierarchical porous carbon aerogels derived from chitosan in this study. The 1D nanostructures grow on the channel surface of the carbon aerogel vertically and tightly, contributing to the enhanced electrochemical performance with ultrahigh energy density. The energy density of NiCo 2 S 4 nanotube array/carbon aerogel and NiCo 2 O 4 nanoneedle array/carbon aerogel hybrid asymmetric supercapacitors can reach up to 55.3 Wh kg -1 and 47.5 Wh kg -1 at a power density of 400 W kg -1 , respectively. These asymmetric devices also displayed excellent cycling stability with a capacitance retention of about 96.6% and 92% over 5000 cycles.

An artificial light-harvesting array constructed from multiple Bodipy dyes.

PubMed

Ziessel, Raymond; Ulrich, Gilles; Haefele, Alexandre; Harriman, Anthony

2013-07-31

An artificial light-harvesting array, comprising 21 discrete chromophores arranged in a rational manner, has been synthesized and characterized fully. The design strategy follows a convergent approach that leads to a molecular-scale funnel, having an effective chromophore concentration of 0.6 M condensed into ca. 55 nm(3), able to direct the excitation energy to a focal point. A cascade of electronic energy-transfer steps occurs from the rim to the focal point, with the rate slowing down as the exciton moves toward its ultimate target. Situated midway along each branch of the V-shaped array, two chromophoric relays differ only slightly in terms of their excitation energies, and this situation facilitates reverse energy transfer. Thus, the excitation energy becomes spread around the array, a situation reminiscent of a giant holding pattern for the photon that can sample many different chromophores before being trapped by the terminal acceptor. At high photon flux under conditions of relatively slow off-load to a device, such as a solar cell, electronic energy transfer encounters one or more barriers that hinder forward progress of the exciton and thereby delays arrival of the second photon. Preliminary studies have addressed the ability of the array to function as a sensitizer for amorphous silicon solar cells.

Nanocrystalline diamond micro-anvil grown on single crystal diamond as a generator of ultra-high pressures

DOE PAGES

Samudrala, Gopi K.; Moore, Samuel L.; Velisavljevic, Nenad; ...

2016-09-29

By combining mask-less lithography and chemical vapor deposition (CVD) techniques, a novel two-stage diamond anvil has been fabricated. A nanocrystalline diamond (NCD) micro-anvil 30 μm in diameter was grown at the center of a [100]-oriented, diamond anvil by utilizing microwave plasma CVD method. The NCD micro-anvil has a diamond grain size of 115 nm and micro-focused Raman and X-ray Photoelectron spectroscopy analysis indicate sp3-bonded diamond content of 72%. Lastly, these CVD grown NCD micro-anvils were tested in an opposed anvil configuration and the transition metals osmium and tungsten were compressed to high pressures of 264 GPa in a diamond anvilmore » cell.« less

Dynamically reconfigurable holographic metasurface aperture for a Mills-Cross monochromatic microwave camera.

PubMed

Yurduseven, Okan; Marks, Daniel L; Fromenteze, Thomas; Smith, David R

2018-03-05

We present a reconfigurable, dynamic beam steering holographic metasurface aperture to synthesize a microwave camera at K-band frequencies. The aperture consists of a 1D printed microstrip transmission line with the front surface patterned into an array of slot-shaped subwavelength metamaterial elements (or meta-elements) dynamically tuned between "ON" and "OFF" states using PIN diodes. The proposed aperture synthesizes a desired radiation pattern by converting the waveguide-mode to a free space radiation by means of a binary modulation scheme. This is achieved in a holographic manner; by interacting the waveguide-mode (reference-wave) with the metasurface layer (hologram layer). It is shown by means of full-wave simulations that using the developed metasurface aperture, the radiated wavefronts can be engineered in an all-electronic manner without the need for complex phase-shifting circuits or mechanical scanning apparatus. Using the dynamic beam steering capability of the developed antenna, we synthesize a Mills-Cross composite aperture, forming a single-frequency all-electronic microwave camera.

Design of novel artemisinin-like derivatives with cytotoxic and anti-angiogenic properties

PubMed Central

Soomro, Shahid; Langenberg, Tobias; Mahringer, Anne; Konkimalla, V Badireenath; Horwedel, Cindy; Holenya, Pavlo; Brand, Almut; Cetin, Canan; Fricker, Gert; Dewerchin, Mieke; Carmeliet, Peter; Conway, Edward M; Jansen, Herwig; Efferth, Thomas

2011-01-01

Abstract Artemisinins are plant products with a wide range of medicinal applications. Most prominently, artesunate is a well tolerated and effective drug for treating malaria, but is also active against several protozoal and schistosomal infections, and additionally exhibits anti-angiogenic, anti-tumorigenic and anti-viral properties. The array of activities of the artemisinins, and the recent emergence of malaria resistance to artesunate, prompted us to synthesize and evaluate several novel artemisinin-like derivatives. Sixteen distinct derivatives were therefore synthesized and the in vitro cytotoxic effects of each were tested with different cell lines. The in vivo anti-angiogenic properties were evaluated using a zebrafish embryo model. We herein report the identification of several novel artemisinin-like compounds that are easily synthesized, stable at room temperature, may overcome drug-resistance pathways and are more active in vitro and in vivo than the commonly used artesunate. These promising findings raise the hopes of identifying safer and more effective strategies to treat a range of infections and cancer. PMID:20629994

The flow separation delay in the boundary layer by induced vortices.

PubMed

Chaudhry, Ishtiaq A; Sultan, Tipu; Siddiqui, Farrukh A; Farhan, M; Asim, M

2017-01-01

A series of experiments involving the particle image velocimetry technique are carried out to analyse the quantitative effectiveness of the synthesized vortical structures towards actual flow separation control. The streamwise vortices are synthesized from the synthetic jet actuator and introduced into the attached and separating boundary layer developed on the flat plate surface. Two types of actuators with different geometrical set-ups are used to analyse the evolution of vortical structures in the near wall region and their impact towards achieving separation delay in the boundary layer. First, a single circular jet is synthesized by varying actuator operating parameters and issued into the boundary layer to evaluate the dynamics of the interaction between the vortical structures and the near wall low momentum fluid in the separated region. Second, an array of jets has been issued into the artificially separated region to assess the effectiveness of various vortical structures towards achieving the reattachment of the separated flow in the streamwise direction.

The synthesis of graphene from palm oil at different annealing time of nickel substrate via thermal chemical vapor deposition

NASA Astrophysics Data System (ADS)

Salifairus, M. J.; Soga, T.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Graphene has shown a plethora potential of applications with its extraordinary electronic and mechanical properties. It is a 2D carbon allotrope which carbon atoms are arrayed in a hexagonal honeycomb lattice. Graphene was synthesized on the polycrystalline nickel substrate with a dimension of 0.10 mm × 10 mm × 10 mm via thermal chemical vapor deposition (TCVD). The carbon precursor was obtained from a commercial palm oil as a natural carbon source. The D, G, and 2D bands described the vibration of graphitic layer and overtone of the D band at 1357, 1595 and 2703 cm-1 respectively. The lowest G band full width at half maximum (FWHM) was 42.95 cm-1 at 15 minutes annealing time. Raman spectroscopy, UV-vis spectrophotometry, atomic force microscopy, XRD and field emission scanning microscopy characterized the synthesized graphene. Multi-layer graphene was successfully synthesized from the palm oil via TCVD.

Toward Evolvable Hardware Chips: Experiments with a Programmable Transistor Array

NASA Technical Reports Server (NTRS)

Stoica, Adrian

1998-01-01

Evolvable Hardware is reconfigurable hardware that self-configures under the control of an evolutionary algorithm. We search for a hardware configuration can be performed using software models or, faster and more accurate, directly in reconfigurable hardware. Several experiments have demonstrated the possibility to automatically synthesize both digital and analog circuits. The paper introduces an approach to automated synthesis of CMOS circuits, based on evolution on a Programmable Transistor Array (PTA). The approach is illustrated with a software experiment showing evolutionary synthesis of a circuit with a desired DC characteristic. A hardware implementation of a test PTA chip is then described, and the same evolutionary experiment is performed on the chip demonstrating circuit synthesis/self-configuration directly in hardware.

Structural and optical properties of glancing angle deposited TiO2 nanowires array.

PubMed

Chinnamuthu, P; Mondal, A; Singh, N K; Dhar, J C; Das, S K; Chattopadhyay, K K

2012-08-01

TiO2 nanowires (NWs) have been synthesized by glancing angle deposition technique using e-beam evaporator. The average length 490 nm and diameter 80 nm of NWs were examined by field emission-scanning electron microscopy. Transmission electron microscopy emphasized that the NWs were widely dispersed at the top. X-ray diffraction has been carried out on the TiO2 thin film (TF) and NW array. A small blue shift of 0.03 eV was observed in Photoluminescence (PL) main band emission for TiO2 NW as compared to TiO2 TF. The high temperature annealing at 980 degrees C partially removed the oxygen vacancy from the sample, which was investigated by PL and optical absorption measurements.

Enhanced performance of core-shell structured polyaniline at helical carbon nanotube hybrids for ammonia gas sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Xin; Wang, Qiang; Chen, Xiangnan

2014-11-17

A core-shell structured hybrid of polyaniline at helical carbon nanotubes was synthesized using in situ polymerization, which the helical carbon nanotubes were uniformly surrounded by a layer of polyaniline nanorods array. More interestingly, repeatable responses were experimentally observed that the sensitivity to ammonia gas of the as-prepared helical shaped core-shell hybrid displays an enhancement of more than two times compared to those of only polyaniline or helical carbon nanotubes sensors because of the peculiar structures with high surface area. This kind of hybrid comprising nanorod arrays of conductive polymers covering carbon nanotubes and related structures provide a potential in sensorsmore » of trace gas detection for environmental monitoring and safety forecasting.« less

One-dimensional array of gold nanoparticles fabricated using biotemplate and its application to fine FET

NASA Astrophysics Data System (ADS)

Ban, Takahiko; Uenuma, Mutsunori; Migita, Shinji; Okamoto, Naofumi; Ishikawa, Yasuaki; Uraoka, Yukiharu; Yamashita, Ichiro; Yamamoto, Shin-ichi

2018-06-01

By synthesizing AuS nanoparticles (NPs) with spherical shell protein (ferritin) and using a V-groove, a one-dimensional array of NPs was formed at the bottom of the V-groove. It has been reported that AuS NPs are converted to Au NPs by UV/ozone treatment. Floating gate memory (FGM) was fabricated by applying this one-dimensional array to V-grooved junctionless (JL) FETs, V-grooved nin-like-type FETs, and pip-like-type FETs, which are fine FETs. In JL-FETs, it is considered that conversion occurred because of good charge storage efficiency, and operation in the opposite direction to normal FGM operation was seen. In the nin-like and pip-like types devices, the same operation as in conventional FGM was shown, and the width of the memory window was about the same size as when one electron entered one NP. The one-dimensional arrangement of the metal NPs used in this study is considered to be applicable to various fields of nanotechnology.

Arrays of Molecular Rotors with Triptycene Stoppers: Surface Inclusion in Hexagonal Tris(o-phenylenedioxy)cyclotriphosphazene.

PubMed

Kaleta, Jiří; Dron, Paul I; Zhao, Ke; Shen, Yongqiang; Císařová, Ivana; Rogers, Charles T; Michl, Josef

2015-06-19

A new generation of rod-shaped dipolar molecular rotors designed for controlled insertion into channel arrays in the surface of hexagonal tris(o-phenylenedioxy)cyclotriphosphazene (TPP) has been designed and synthesized. Triptycene is used as a stopper intended to prevent complete insertion, forcing the formation of a surface inclusion. Two widely separated (13)C NMR markers are present in the shaft for monitoring the degree of insertion. The structure of the two-dimensional rotor arrays contained in these surface inclusions was examined by solid-state NMR and X-ray powder diffraction. The NMR markers and the triptycene stopper functioned as designed, but half of the guest molecules were not inserted as deeply into the TPP channels as the other half. As a result, the dipolar rotators were distributed equally in two planes parallel to the crystal surface instead of being located in a single plane as would be required for ferroelectricity. Dielectric spectroscopy revealed rotational barriers of ∼4 kcal/mol but no ferroelectric behavior.

Nano-engineering of three-dimensional core/shell nanotube arrays for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Grote, Fabian; Wen, Liaoyong; Lei, Yong

2014-06-01

Large-scale arrays of core/shell nanostructures are highly desirable to enhance the performance of supercapacitors. Here we demonstrate an innovative template-based fabrication technique with high structural controllability, which is capable of synthesizing well-ordered three-dimensional arrays of SnO2/MnO2 core/shell nanotubes for electrochemical energy storage in supercapacitor applications. The SnO2 core is fabricated by atomic layer deposition and provides a highly electrical conductive matrix. Subsequently a thin MnO2 shell is coated by electrochemical deposition onto the SnO2 core, which guarantees a short ion diffusion length within the shell. The core/shell structure shows an excellent electrochemical performance with a high specific capacitance of 910 F g-1 at 1 A g-1 and a good rate capability of remaining 217 F g-1 at 50 A g-1. These results shall pave the way to realize aqueous based asymmetric supercapacitors with high specific power and high specific energy.

Design and application of a small size SAFT imaging system for concrete structure

NASA Astrophysics Data System (ADS)

Shao, Zhixue; Shi, Lihua; Shao, Zhe; Cai, Jian

2011-07-01

A method of ultrasonic imaging detection is presented for quick non-destructive testing (NDT) of concrete structures using synthesized aperture focusing technology (SAFT). A low cost ultrasonic sensor array consisting of 12 market available low frequency ultrasonic transducers is designed and manufactured. A channel compensation method is proposed to improve the consistency of different transducers. The controlling devices for array scan as well as the virtual instrument for SAFT imaging are designed. In the coarse scan mode with the scan step of 50 mm, the system can quickly give an image display of a cross section of 600 mm (L) × 300 mm (D) by one measurement. In the refined scan model, the system can reduce the scan step and give an image display of the same cross section by moving the sensor array several times. Experiments on staircase specimen, concrete slab with embedded target, and building floor with underground pipe line all verify the efficiency of the proposed method.

Flexible ultraviolet photodetectors based on ZnO-SnO2 heterojunction nanowire arrays

NASA Astrophysics Data System (ADS)

Lou, Zheng; Yang, Xiaoli; Chen, Haoran; Liang, Zhongzhu

2018-02-01

A ZnO-SnO2 nanowires (NWs) array, as a metal oxide semiconductor, was successfully synthesized by a near-field electrospinning method for the applications as high performance ultraviolet photodetectors. Ultraviolet photodetectors based on a single nanowire exhibited excellent photoresponse properties to 300 nm ultraviolet light illumination including ultrahigh I on/I off ratios (up to 103), good stability and reproducibility because of the separation between photo-generated electron-hole pairs. Moreover, the NWs array shows an enhanced photosensing performance. Flexible photodetectors on the PI substrates with similar tendency properties were also fabricated. In addition, under various bending curvatures and cycles, the as-fabricated flexible photodetectors revealed mechanical flexibility and good stable electrical properties, showing that they have the potential for applications in future flexible photoelectron devices. Project supported by the National Science Foundation of China (No. 61504136) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine and Physics, Chinese Academy of Sciences.

Building one-dimensional oxide nanostructure arrays on conductive metal substrates for lithium-ion battery anodes.

PubMed

Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

2011-01-01

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

Correlation processing for correction of phase distortions in subaperture imaging.

PubMed

Tavh, B; Karaman, M

1999-01-01

Ultrasonic subaperture imaging combines synthetic aperture and phased array approaches and permits low-cost systems with improved image quality. In subaperture processing, a large array is synthesized using echo signals collected from a number of receive subapertures by multiple firings of a phased transmit subaperture. Tissue inhomogeneities and displacements in subaperture imaging may cause significant phase distortions on received echo signals. Correlation processing on reference echo signals can be used for correction of the phase distortions, for which the accuracy and robustness are critically limited by the signal correlation. In this study, we explore correlation processing techniques for adaptive subaperture imaging with phase correction for motion and tissue inhomogeneities. The proposed techniques use new subaperture data acquisition schemes to produce reference signal sets with improved signal correlation. The experimental test results were obtained using raw radio frequency (RF) data acquired from two different phantoms with 3.5 MHz, 128-element transducer array. The results show that phase distortions can effectively be compensated by the proposed techniques in real-time adaptive subaperture imaging.

Building one-dimensional oxidenanostructure arrays on conductive metal substrates for lithium-ion battery anodes

NASA Astrophysics Data System (ADS)

Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

2011-01-01

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized aluminamembrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

Gene chips and arrays revealed: a primer on their power and their uses.

PubMed

Watson, S J; Akil, H

1999-03-01

This article provides an overview and general explanation of the rapidly developing area of gene chips and expression array technology. These are methods targeted at allowing the simultaneous study of thousands of genes or messenger RNAs under various physiological and pathological states. Their technical basis grows from the Human Genome Project. Both methods place DNA strands on glass computer chips (or microscope slides). Expression arrays start with complementary DNA (cDNA) clones derived from the EST data base, whereas Gene Chips synthesize oligonucleotides directly on the chip itself. Both are analyzed using image analysis systems, are capable of reading values from two different individuals at any one site, and can yield quantitative data for thousands of genes or mRNAs per slide. These methods promise to revolutionize molecular biology, cell biology, neuroscience and psychiatry. It is likely that this technology will radically open up our ability to study the actions and structure of the multiple genes involved in the complex genetics of brain disorders.

GaAs nanopillar-array solar cells employing in situ surface passivation

PubMed Central

Mariani, Giacomo; Scofield, Adam C.; Hung, Chung-Hong; Huffaker, Diana L.

2013-01-01

Arrays of III–V direct-bandgap semiconductor nanopillars represent promising photovoltaic candidates due to their inherent high optical absorption coefficients and minimized reflection arising from light trapping, efficient charge collection in the radial direction and the ability to synthesize them on low-cost platforms. However, the increased surface area results in surface states that hamper the power conversion efficiency. Here, we report the first demonstration of GaAs nanopillar-array photovoltaics employing epitaxial passivation with air mass 1.5 global power conversion efficiencies of 6.63%. High-bandgap epitaxial InGaP shells are grown in situ and cap the radial p–n junctions to alleviate surface-state effects. Under light, the photovoltaic devices exhibit open-circuit voltages of 0.44 V, short-circuit current densities of 24.3 mA cm−2 and fill factors of 62% with high external quantum efficiencies >70% across the spectral regime of interest. A novel titanium/indium tin oxide annealed alloy is exploited as transparent ohmic anode. PMID:23422665

Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors.

PubMed

Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

2011-05-01

Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g(-1) at 1 A g(-1), which remained at 543 F g(-1) when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg(-1)) was maintained even at a high power density of 6000 W kg(-1). An excellent long cycle life of the electrode was observed with a retention of ∼86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO(2) nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications. © The Royal Society of Chemistry 2011

High precision computing with charge domain devices and a pseudo-spectral method therefor

NASA Technical Reports Server (NTRS)

Barhen, Jacob (Inventor); Toomarian, Nikzad (Inventor); Fijany, Amir (Inventor); Zak, Michail (Inventor)

1997-01-01

The present invention enhances the bit resolution of a CCD/CID MVM processor by storing each bit of each matrix element as a separate CCD charge packet. The bits of each input vector are separately multiplied by each bit of each matrix element in massive parallelism and the resulting products are combined appropriately to synthesize the correct product. In another aspect of the invention, such arrays are employed in a pseudo-spectral method of the invention, in which partial differential equations are solved by expressing each derivative analytically as matrices, and the state function is updated at each computation cycle by multiplying it by the matrices. The matrices are treated as synaptic arrays of a neural network and the state function vector elements are treated as neurons. In a further aspect of the invention, moving target detection is performed by driving the soliton equation with a vector of detector outputs. The neural architecture consists of two synaptic arrays corresponding to the two differential terms of the soliton-equation and an adder connected to the output thereof and to the output of the detector array to drive the soliton equation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Anguo, E-mail: hixiaoanguo@126.com; Zhou, Shibiao; Zuo, Chenggang

Graphical abstract: CuO nanotube array electrodes prepared by electrodeposition method exhibit an excellent lithium ion storage ability as anode of Li-ion battery. - Highlights: • CuO nanotube arrays are synthesized by an electrodeposition method. • CuO nanotube shows a high-rate performance. • CuO nanotube shows an excellent cycling performance. - Abstract: We report a facile strategy to prepared CuO nanotube arrays directly grown on Cu plate through the electrodeposition method. The as-prepared CuO nanotubes show a quasi-cylinder nanostructure with internal diameters of ca. ∼100 nm, external diameters of ca. ∼120 nm, and average length of ∼3 μm. As an anodemore » for lithium ion batteries, the electrochemical properties of the CuO nanotube arrays are investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. Due to the unique nanotube nanostructure, the as-prepared CuO electrodes exhibit good rate performance (550 mAh g{sup −1} at 0.1 C and 464 mAh g{sup −1} at 1 C) and cycling performance (581 mAh g{sup −1} at 0.1 C and 538 mAh g{sup −1} at 0.5 C)« less

Biological properties of nanostructured Ti incorporated with Ca, P and Ag by electrochemical method.

PubMed

Li, Baoe; Hao, Jingzu; Min, Yang; Xin, Shigang; Guo, Litong; He, Fei; Liang, Chunyong; Wang, Hongshui; Li, Haipeng

2015-06-01

TiO2 nanotube arrays were synthesized on Ti surface by anodic oxidation. The elements of Ca and P were simultaneously incorporated during nanotubes growth in SBF electrolyte, and then Ag was introduced to nanotube arrays by cathodic deposition, which endowed the good osseointegration and antibacterial property of Ti. The bioactivity of the Ti surface was evaluated by simulated body fluid soaking test. The biocompatibility was investigated by in vitro cell culture test. And the antibacterial effect against Staphylococcus aureus was examined by the bacterial counting method. The results showed that the incorporation of Ca, P and Ag elements had no significant influence on the formation of nanotube arrays on Ti surface during electrochemical treatment. Compared to the polished or nanotubular Ti surface, TiO2 nanotube arrays incorporated with Ca, P and Ag increased the formation of bone-like apatite in simulated body fluid, enhanced cell adhesion and proliferation, and inhibited the bacterial growth. Based on these results, it can be concluded that the nanostructured Ti incorporated with Ca, P and Ag by electrochemical method has promising applications as implant material. Copyright © 2015 Elsevier B.V. All rights reserved.

Logic Nanocells Within 3-Terminal Ordered Arrays

DTIC Science & Technology

2007-02-28

DISTRIBUTION/AVAILABILITY STATEMENT DISTRIBUTION STATEMEN A: UNLIMITED AFRL- SR -AR-TR-07-0494 13. SUPPLEMENTARY NOTES 14. ABSTRACT ON SEPARATE SHEET... sputter -coating a 200 nm Au layer. Molecular grafting. Compounds 1, 2 and 3 were synthesized according to literature methods.24 26 The synthesis of 4...neutral (no counter ions ). In order to facilitate molecular conduction, the molecule was designed to be small and contain a continuous Tr-electron system

Fillers: from the past to the future.

PubMed

Glogau, Richard G

2012-06-01

Modern medical use of injectable soft-tissue augmentation fillers has evolved from the introduction of bovine collage implants to an array of synthesized materials in the current domestic and foreign markets. The concept of augmentation has moved from simple lines, scars, and wrinkles to revolumizing the aging face. A brief overview of the past, present, and future injectable fillers is presented. Copyright © 2012 Elsevier Inc. All rights reserved.

Naturally occurring anti-glycan antibodies binding to Globo H-expressing cells identify ovarian cancer patients.

PubMed

Pochechueva, Tatiana; Alam, Shahidul; Schötzau, Andreas; Chinarev, Alexander; Bovin, Nicolai V; Hacker, Neville F; Jacob, Francis; Heinzelmann-Schwarz, Viola

2017-02-10

Glycosphingolipids are important compounds of the plasma membrane of mammalian cells and a number of them have been associated with malignant transformation and progression, reinforcing tumour aggressiveness and metastasis. Here we investigated the levels of naturally occurring anti-glycan antibodies to Globo H in blood plasma obtained from high-grade serous ovarian cancer patients (SOC) and women without gynaecological malignancies (control) using suspension glycan array technology employing chemically synthesized glycans as antibody targets. We found that anti-human Globo H IgG antibodies were able to significantly discriminate SOC from controls (P < 0.05). A combination with the clinically used tumour marker CA125 increased the diagnostic performance (AUC 0.8711). We next compared suspension array with standard flow cytometry in plasma samples and found that the level of anti-Globo H antibodies highly correlated (r = 0.992). The incubation of plasma-derived anti-glycan antibodies with chemically synthesized (presented on fluorescence microspheres) and native Globo H (expressed on Globo H-positive cell lines) revealed strong reactivity of naturally occurring human anti-Globo H antibodies towards its antigen expressed on ovarian cancer cells. Our data demonstrate that human plasma-derived antibodies to Globo H as well as the presence of the antigen might be considered as therapeutic option in ovarian cancer.

Flexible asymmetric supercapacitors based upon Co9S8 nanorod//Co3O4@RuO2 nanosheet arrays on carbon cloth.

PubMed

Xu, Jing; Wang, Qiufan; Wang, Xiaowei; Xiang, Qingyi; Liang, Bo; Chen, Di; Shen, Guozhen

2013-06-25

We have successfully fabricated flexible asymmetric supercapacitors (ASCs) based on acicular Co9S8 nanorod arrays as positive materials and Co3O4@RuO2 nanosheet arrays as negative materials on woven carbon fabrics. Co9S8 nanorod arrays were synthesized by a hydrothermal sulfuration treatment of acicular Co3O4 nanorod arrays, while the RuO2 was directly deposited on the Co3O4 nanorod arrays. Carbon cloth was selected as both the substrate and the current collector for its good conductivity, high flexibility, good physical strength, and lightweight architecture. Both aqueous KOH solutions and polyvinyl alcohol (PVA)/KOH were employed as electrolyte for electrochemical measurements. The as-fabricated ASCs can be cycled reversibly in the range of 0-1.6 V and exhibit superior electrochemical performance with an energy density of 1.21 mWh/cm(3) at a power density of 13.29 W/cm(3) in aqueous electrolyte and an energy density of 1.44 mWh/cm(3) at the power density of 0.89 W/cm(3) in solid-state electrolyte, which are almost 10-fold higher than those reported in early ASC work. Moreover, they present excellent cycling performance at multirate currents and large currents after thousands of cycles. The high-performance nanostructured ASCs have significant potential applications in portable electronics and electrical vehicles.

Sunlight-Driven Hydrogen Formation by Membrane-Supported Photoelectrochemical Water Splitting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Nathan S.

2014-03-26

This report describes the significant advances in the development of the polymer-supported photoelectrochemical water-splitting system that was proposed under DOE grant number DE-FG02-05ER15754. We developed Si microwire-array photoelectrodes, demonstrated control over the material and light-absorption properties of the microwire-array photoelectrodes, developed inexpensive processes for synthesizing the arrays, and doped the arrays p-type for use as photocathodes. We also developed techniques for depositing metal-nanoparticle catalysts of the hydrogen-evolution reaction (HER) on the wire arrays, investigated the stability and catalytic performance of the nanoparticles, and demonstrated that Ni-Mo alloys are promising earth-abundant catalysts of the HER. We also developed methods that allowmore » reuse of the single-crystalline Si substrates used for microwire growth and methods of embedding the microwire photocathodes in plastic to enable large-scale processing and deployment of the technology. Furthermore we developed techniques for controlling the structure of WO3 films, and demonstrated that structural control can improve the quantum yield of photoanodes. Thus, by the conclusion of this project, we demonstrated significant advances in the development of all components of a sunlight-driven membrane-supported photoelectrochemical water-splitting system. This final report provides descriptions of some of the scientific accomplishments that were achieved under the support of this project and also provides references to the peer-reviewed publications that resulted from this effort.« less

Self-Supported CoP Nanorod Arrays Grafted on Stainless Steel as an Advanced Integrated Anode for Stable and Long-Life Lithium-Ion Batteries.

PubMed

Xu, Xijun; Liu, Jun; Hu, Renzong; Liu, Jiangwen; Ouyang, Liuzhang; Zhu, Min

2017-04-19

To alleviate the capacity degradation of anode materials for Li-ion batteries, caused by serious volume expansion and particle aggregation, intensive attention has been devoted to the rational design and fabrication of novel anode architectures. Herein, self-supported CoP nanorod arrays have been facilely synthesized using hydrothemally deposited Co(CO 3 ) 0.5 (OH)⋅0.11 H 2 O nanorod arrays as the precursor, through a gas-phase phosphidation method. As the anode for Li-ion batteries, such 3D interconnected CoP nanorod arrays show an initial discharge capacity of 1067 mAh g -1 and a high reversible charge capacity of 737 mAh g -1 at 0.4 Ag -1 . After 400 cycles, their specific capacity can reach 510 mAh g -1 ; even after 900 cycles, they can still deliver a specific capacity of 390 mAh g -1 . CoP//LiCoO 2 full-cells also exhibit a high reversible capacity of 400 mAh g -1 after 50 cycles. These unique 3D interconnected CoP nanorod arrays also show ultrastable cycling performance over 500 cycles when used as the anode in a Na-ion battery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of TiO2/functionalized graphene sheets (FGSs) nanocomposites in super critical CO2

NASA Astrophysics Data System (ADS)

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chen, Bo; Charpentier, Paul A.

2010-06-01

Highly ordered TiO2 nanowire arrays were prepared on the surface of Functionalized Graphene sheets (FGSs) by solgel method using titanium isopropoxide monomer with acetic acid as the polycondensation agent in the green solvent, supercritical carbon dioxide (sc-CO2). Morphology of synthesized materials was studied by SEM and TEM. Optical properties of the nanocomposites studied by UV spectroscopy which showed high absorption in visible area as well as reduction in their band gap compared to TiO2. By high resolution XPS, chelating bidentate structure of TiO2 with carboxylic group on the surface of graphene sheets can be confirmed. Improvement in the optical properties of the synthesized composites compared to TiO2 alone was confirmed by photocurrent measurements.

Preparation, characterization and photocatalytic activities of TiO2-SrTiO3 composites

NASA Astrophysics Data System (ADS)

Wang, Yan; Zhu, Lianjie; Gao, Fubo; Xie, Hanjie

2017-01-01

Series of TiO2-SrTiO3 composites were synthesized by hydrothermal method, using TiO2 nanotube array as a precursor and Sr(OH)2 as a Sr source material. TiO2-SrTiO3 products with various composition were obtained by simply changing the reaction time. The as-synthesized products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical properties were studied by means of UV-Vis absorption spectroscopy and photoluminescence (PL) spectra. Their photocatalytic activities were assessed by photodegradation of rhodamine B (RhB) solution and the photocatalytic reaction mechanism was discussed. The TiO2-SrTiO3 composites obtained at 2 h exhibits the highest activity for photodegradation of RhB.

Manganese oxide arrays on carbon fiber paper and its application for PEMFC

NASA Astrophysics Data System (ADS)

Lu, Lu; Zhao, Yu; Deng, Han; Xu, Bing

2018-02-01

C-MnO2 was synthesized by direct hydrothermal decomposition of KMnO4. The structure and morphology of C-MnO2 was characterized by XRD and SEM, electrochemical performances were investigated by cyclic voltammetry. The effects of hydrothermal temperatures, and time were systemat ically investigated. The XRD pattern can be identified as a α-types space group, and it matches well with Bragg reflection of the standard α-MnO2, suggesting that a targeted α-MnO2 has been successfully synthesized. The results show that pure phase MnO2 nanorods can be obtained in 160 °C. C-MnO2 composites show a larger current response and C-MnO2 composite material has improved the efficiency of the large current charge and discharge.

Synthesis of Antiproliferative Cephalotaxus Esters and Their Evaluation against Several Human Hematopoietic and Solid Tumor Cell Lines: Uncovering Differential Susceptibilities to Multidrug Resistance

PubMed Central

Eckelbarger, Joseph D.; Wilmot, Jeremy T.; Epperson, Matthew T.; Thakur, Chandar S.; Shum, David; Antczak, Christophe; Tarassishin, Leonid; Djaballah, Hakim; Gin, David Y.

2008-01-01

Deoxyharringtonine (2), homoharringtonine (3), homodeoxyharringtonine (4), and anhydroharringtonine (5) are reported to be among the most potent members of the antileukemia alkaloids isolated from the Cephalotaxus genus. Convergent syntheses of these four natural products are described, each involving novel synthetic methods and strategies. These syntheses enabled evaluation of several advanced natural and non-natural compounds against an array of human hematopoietic and solid tumor cells. Potent cytotoxicity was observed in several cell lines previously not challenged with these alkaloids. Variations in the structure of the ester chain within this family of alkaloids confer differing activity profiles against vincristine-resistant HL-60/RV+, signalling new avenues for molecular design of these natural products to combat multi-drug resistance. PMID:18366032

Morphological evolution and characterization of GaN pyramid arrays fabricated by photo-assisted chemical etching

NASA Astrophysics Data System (ADS)

Zhang, Shiying; Xiu, Xiangqian; Xu, Qingjun; Li, Yuewen; Hua, Xuemei; Chen, Peng; Xie, Zili; Liu, Bin; Zhou, Yugang; Han, Ping; Zhang, Rong; Zheng, Youdou

2016-12-01

GaN pyramid arrays have been successfully synthesized by selective photo-assisted chemical etching in a K2S2O8/KOH solution. A detailed analysis of time evolution of surface morphology has been conducted, which describes an etching process of GaN pyramids. Room temperature cathodoluminescence images indicate that these pyramids are composed of crystalline GaN surrounding dislocations, which is caused by the greater recombination rate of electrons and holes at dislocation than that of crystalline GaN. The Raman results show a stress relaxation in GaN pyramids compared with unetched GaN. The optical property of both unetched GaN and GaN pyramids has been studied by photoluminescence. The formation mechanism and feature of GaN pyramids are also rationally explained.

MAGIC: a European program to push the insertion of maskless lithography

NASA Astrophysics Data System (ADS)

Pain, L.; Icard, B.; Tedesco, S.; Kampherbeek, B.; Gross, G.; Klein, C.; Loeschner, H.; Platzgummer, E.; Morgan, R.; Manakli, S.; Kretz, J.; Holhe, C.; Choi, K.-H.; Thrum, F.; Kassel, E.; Pilz, W.; Keil, K.; Butschke, J.; Irmscher, M.; Letzkus, F.; Hudek, P.; Paraskevopoulos, A.; Ramm, P.; Weber, J.

2008-03-01

With the willingness of the semiconductor industry to push manufacturing costs down, the mask less lithography solution represents a promising option to deal with the cost and complexity concerns about the optical lithography solution. Though a real interest, the development of multi beam tools still remains in laboratory environment. In the frame of the seventh European Framework Program (FP7), a new project, MAGIC, started January 1st 2008 with the objective to strengthen the development of the mask less technology. The aim of the program is to develop multi beam systems from MAPPER and IMS nanofabrication technologies and the associated infrastructure for the future tool usage. This paper draws the present status of multi beam lithography and details the content and the objectives of the MAGIC project.

Influence of the morphology of ZnO nanostructures on luminescent and photovoltaic properties

NASA Astrophysics Data System (ADS)

Ibrayev, N. Kh.; Ilyassov, B. R.; Afanasyev, D. A.

2017-03-01

Arrays of ZnO nanorods and nanoplates are synthesized by the hydrothermal and electrochemical methods, respectively. The photoluminescence spectra indicate that the nanoplates have a more defective structure than the nanorods. The obtained ZnO nanostructures are used as the basis to construct dye-sensitized solar cells. The influence of morphology and defectiveness of ZnO nanostructures on the luminescent and photovoltaic properties of the cells is studied.

Vapor deposition routes to conformal polymer thin films

PubMed Central

Moni, Priya; Al-Obeidi, Ahmed

2017-01-01

Vapor phase syntheses, including parylene chemical vapor deposition (CVD) and initiated CVD, enable the deposition of conformal polymer thin films to benefit a diverse array of applications. This short review for nanotechnologists, including those new to vapor deposition methods, covers the basic theory in designing a conformal polymer film vapor deposition, sample preparation and imaging techniques to assess film conformality, and several applications that have benefited from vapor deposited, conformal polymer thin films. PMID:28487816

“Click, Click, Cyclize”: A DOS Approach to Sultams Utilizing Vinyl Sulfonamide Linchpins

PubMed Central

Zhou, Aihua; Rayabarapu, Dinesh; Hanson, Paul R.

2009-01-01

A diversity-oriented synthesis (DOS) strategy termed “Click, Click, Cyclize” is reported. This approach relies on functional group (FG) pairing between a vinyl sulfonamide and an array of functional groups to synthesize skeletally diverse sultams. Several FG pairing pathways on central tertiary vinyl sulfonamide linchpins have been developed including intramolecular Heck, aza-Michael, ring-closing enyne metathesis, Pauson—Khand, and chemoselective oxidation/Baylis—Hillman reactions. PMID:19115841

Efficient Förster resonance energy transfer in 1,2,3-triazole linked BODIPY-Zn(II) meso-tetraphenylporphyrin donor-acceptor arrays.

PubMed

Leonardi, Matthew J; Topka, Michael R; Dinolfo, Peter H

2012-12-17

Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC) reactivity was successfully employed to synthesize three donor-acceptor energy transfer (EnT) arrays that contain one (Dyad), three (Tetrad) and four (Pentad) 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) donors connected to a Zn-tetraphenylporphyrin acceptor via 1,2,3-triazole linkages. The photophysical properties of the three arrays, along with individual donor and acceptor chromophores, were investigated by UV-vis absorption and emission spectroscopy, fluorescence lifetimes, and density functional theory (DFT) electronic structure modeling. Comparison of the UV-vis absorption spectra and frontier molecular orbitals from DFT calculations of the three arrays with ZnTPP, ZnTTrzlP, and Trzl-BODIPY shows that the electronic structure of the chromophores is essentially unperturbed by the 1,2,3-triazole linkage. Time-dependent DFT (TDDFT) calculations on the Dyad reproduce the absorption spectra in THF and show no evidence of excited state mixing of the donor and acceptor. The BODIPY singlet excited state emission is significantly quenched in all three arrays, consistent with EnT to the porphyrin core, with efficiencies of 95.8, 97.5, and 97.2% for the Dyad, Tetrad, and Pentad, respectively. Fluorescence excitation spectra of the three arrays, measured at the porphyrin emission, mirror the absorption profile of both the porphyrin and BODIPY chromophores and are consistent with the Förster resonance energy transfer (FRET) mechanism. Applying Förster theory to the spectroscopic data of the chromophores gives EnT efficiency estimates that are in close agreement with experimental values, suggesting that the through-space mechanism plays a dominant role in the three arrays.

Top-down synthesized TiO2 nanowires as a solid matrix for surface-assisted laser desorption/ionization time-of-flight (SALDI-TOF) mass spectrometry.

PubMed

Kim, Jo-Il; Park, Jong-Min; Hwang, Seung-Ju; Kang, Min-Jung; Pyun, Jae-Chul

2014-07-11

Top-down synthesized TiO2 nanowires are presented as an ideal solid matrix to analyze small biomolecules at a m/z of less than 500. The TiO2 nanowires were synthesized as arrays using a modified hydrothermal process directly on the surface of a Ti plate. Finally, the feasibility of the TiO2 nanowires in the anatase phase as a solid matrix. The crystal and electronic structures of the top-down TiO2 nanowires were analyzed at each step of the hydrothermal process, and the optimal TiO2 nanowires were identified by checking their performance toward the ionization of analytes in surface-assisted laser desorption/ionization time-of-flight (SALDI-TOF) mass spectrometry. Finally, the feasibility of the TiO2 nanowires in the anatase phase as a solid matrix for SALDI-TOF mass spectrometry was demonstrated using eight types of amino acids and peptides as model analytes. Copyright © 2014 Elsevier B.V. All rights reserved.

Fe doped TiO2 nanofibers on the surface of graphene sheets for photovoltaics applications

NASA Astrophysics Data System (ADS)

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Charpentier, Paul A.

2011-08-01

Highly ordered, visible light driven TiO2 nanowire arrays doped with Fe photocatalysts were grown on the surface of functionalized graphene sheets (FGSs) using a sol-gel method with titanium isopropoxide (TIP) monomer, acetic acid (HAc) as the polycondensation agent and iron chloride in the green solvent, supercritical carbon dioxide (scCO2). The morphology of the synthesized materials was studied by SEM and TEM, which showed uniform formation of Fe doped TiO2 nanofibers on the surface of graphene sheets, which acted as a template for nanowire growth through surface -COOH functionalities. Increasing Fe content in the nanowires did not change the morphology significantly. Optical properties of the synthesized composites were examined by UV spectroscopy which showed a significant reduction in band gap with increasing Fe content, i.e. 2.25 eV at 0.6% Fe. The enhancement of the optical properties of synthesized materials was confirmed by photocurrent measurement. The optimum sample containing 0.6% Fe doped TiO2 on the graphene sheets increased the power conversation efficiency by 6-fold in comparison to TiO2 alone.

Cellulose Microfibril Formation by Surface-Tethered Cellulose Synthase Enzymes.

PubMed

Basu, Snehasish; Omadjela, Okako; Gaddes, David; Tadigadapa, Srinivas; Zimmer, Jochen; Catchmark, Jeffrey M

2016-02-23

Cellulose microfibrils are pseudocrystalline arrays of cellulose chains that are synthesized by cellulose synthases. The enzymes are organized into large membrane-embedded complexes in which each enzyme likely synthesizes and secretes a β-(1→4) glucan. The relationship between the organization of the enzymes in these complexes and cellulose crystallization has not been explored. To better understand this relationship, we used atomic force microscopy to visualize cellulose microfibril formation from nickel-film-immobilized bacterial cellulose synthase enzymes (BcsA-Bs), which in standard solution only form amorphous cellulose from monomeric BcsA-B complexes. Fourier transform infrared spectroscopy and X-ray diffraction techniques show that surface-tethered BcsA-Bs synthesize highly crystalline cellulose II in the presence of UDP-Glc, the allosteric activator cyclic-di-GMP, as well as magnesium. The cellulose II cross section/diameter and the crystal size and crystallinity depend on the surface density of tethered enzymes as well as the overall concentration of substrates. Our results provide the correlation between cellulose microfibril formation and the spatial organization of cellulose synthases.

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

NASA Astrophysics Data System (ADS)

Lin, Burn J.

2007-03-01

Microlithography patterning employs one of three media; electron, ion, and photon. They are in a way like horses, racing towards the mainstream. Some horses such as electrons run fast but repel each other. Ion beams behave like electron beams but are less developed. The photon beam is the undisputed workhorse, taking microlithography from the 5-μm minimum feature size to 32-nm half pitch. This paper examines the history of microlithography in pattern generation, proximity printing, and projection printing, then identifies the strong and weak points of each technology. In addition to ion-beam and e-beam lithography, the coverage of optical lithography spans the wavelength from 436 to 13.5 nm. Our learning from history helps us prevent mistakes in the future. In almost all cases, making or using the mask presents one of the limiting problems, no matter the type of beams or the replication method. Only the maskless method relieves us from mask-related problems. A way to overcome the low throughput handicap of maskless systems is to use multiple e-beam direct writing, whose imaging lens can be economically and compactly fabricated using MEMS techniques. In a way, the history of microlithography parallels that of aviation. Proximity printing is like the Wright-Brothers' plane; 1X projection printing, single-engine propeller plane with unitized body; reduction step-and-repeat projection printing, multi-engine commercial airliner; scanners, jet airliners. Optical lithography has improved in many ways than just increasing NA and reducing wavelength just as the commercial airliners improving in many other areas than just the speed. The SST increased the speed of airliners by more than a factor of two just as optical resolution doubled with double exposures. EUV lithography with the wavelength reduced by an order of magnitude is similar to the space shuttle increasing its speed to more than 10 times that of the SST. Multiple-beam direct write systems are like helicopters. They do not need airports(masks) but we need a lot of beams to carry the same payload.

SU-E-J-12: An Image-Guided Soft Robotic Patient Positioning System for Maskless Head-And-Neck Cancer Radiotherapy: A Proof-Of-Concept Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogunmolu, O; Gans, N; Jiang, S

Purpose: We propose a surface-image-guided soft robotic patient positioning system for maskless head-and-neck radiotherapy. The ultimate goal of this project is to utilize a soft robot to realize non-rigid patient positioning and real-time motion compensation. In this proof-of-concept study, we design a position-based visual servoing control system for an air-bladder-based soft robot and investigate its performance in controlling the flexion/extension cranial motion on a mannequin head phantom. Methods: The current system consists of Microsoft Kinect depth camera, an inflatable air bladder (IAB), pressured air source, pneumatic valve actuators, custom-built current regulators, and a National Instruments myRIO microcontroller. The performance ofmore » the designed system was evaluated on a mannequin head, with a ball joint fixed below its neck to simulate torso-induced head motion along flexion/extension direction. The IAB is placed beneath the mannequin head. The Kinect camera captures images of the mannequin head, extracts the face, and measures the position of the head relative to the camera. This distance is sent to the myRIO, which runs control algorithms and sends actuation commands to the valves, inflating and deflating the IAB to induce head motion. Results: For a step input, i.e. regulation of the head to a constant displacement, the maximum error was a 6% overshoot, which the system then reduces to 0% steady-state error. In this initial investigation, the settling time to reach the regulated position was approximately 8 seconds, with 2 seconds of delay between the command start of motion due to capacitance of the pneumatics, for a total of 10 seconds to regulate the error. Conclusion: The surface image-guided soft robotic patient positioning system can achieve accurate mannequin head flexion/extension motion. Given this promising initial Result, the extension of the current one-dimensional soft robot control to multiple IABs for non-rigid positioning control will be pursued.« less

Microfluidic technology platforms for synthesizing, labeling and measuring the kinetics of transport and biochemical reactions for developing molecular imaging probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phelps, Michael E.

2009-09-01

Radiotracer techniques are used in environmental sciences, geology, biology and medicine. Radiotracers with Positron Emission Tomography (PET) provided biological examinations of ~3 million patients 2008. Despite the success of positron labeled tracers in many sciences, there is limited access in an affordable and convenient manner to develop and use new tracers. Integrated microfluidic chips are a new technology well matched to the concentrations of tracers. Our goal is to develop microfluidic chips and new synthesis approaches to enable wide dissemination of diverse types of tracers at low cost, and to produce new generations of radiochemists for which there are manymore » unfilled jobs. The program objectives are to: 1. Develop an integrated microfluidic platform technology for synthesizing and 18F-labeling diverse arrays of different classes of molecules. 2. Incorporate microfluidic chips into small PC controlled devices (“Synthesizer”) with a platform interfaced to PC for electronic and fluid input/out control. 3. Establish a de-centralized model with Synthesizers for discovering and producing molecular imaging probes, only requiring delivery of inexpensive [18F]fluoride ion from commercial PET radiopharmacies vs the centralized approach of cyclotron facilities synthesizing and shipping a few different types of 18F-probes. 4. Develop a position sensitive avalanche photo diode (PSAPD) camera for beta particles embedded in a microfluidic chip for imaging and measuring transport and biochemical reaction rates to valid new 18F-labeled probes in an array of cell cultures. These objectives are met within a research and educational program integrating radio-chemistry, synthetic chemistry, biochemistry, engineering and biology in the Crump Institute for Molecular Imaging. The Radiochemistry Training Program exposes PhD and post doctoral students to molecular imaging in vitro in cells and microorganisms in microfluidic chips and in vivo with PET, from new technologies for radiochemistry (macro to micro levels), biochemistry and biology to imaging principles, tracer kinetics, pharmacokinetics and biochemical assays. New generations of radiochemists will be immersed in the biochemistry and biology for which their labeled probes are being developed for assays of these processes. In this program engineers and radio-chemists integrate the principles of microfluidics and radiolabeling along with proper system design and chemistry rule sets to yield Synthesizers enabling biological and pharmaceutical scientists to develop diverse arrays of probes to pursue their interests. This progression would allow also radiochemists to focus on the further evolution of rapid, high yield synthetic reactions with new enabling technologies, rather than everyday production of radiotracers that should be done by technologists. The invention of integrated circuits in electronics established a platform technology that allowed an evolution of ideas and applications far beyond what could have been imagined at the beginning. Rather than provide a technology for the solution to a single problem, it is hoped that microfluidic radiochemistry will be an enabling platform technology for others to solve many problems. As part of this objective, another program goal is to commercialize the technologies that come from this work so that they can be provided to others who wish to use it.« less

From GaN to ZnGa(2)O(4) through a low-temperature process: nanotube and heterostructure arrays.

PubMed

Lu, Ming-Yen; Zhou, Xiang; Chiu, Cheng-Yao; Crawford, Samuel; Gradečak, Silvija

2014-01-22

We demonstrate a method to synthesize GaN-ZnGa2O4 core-shell nanowire and ZnGa2O4 nanotube arrays by a low-temperature hydrothermal process using GaN nanowires as templates. Transmission electron microscopy and X-ray photoelectron spectroscopy results show that a ZnGa2O4 shell forms on the surface of GaN nanowires and that the shell thickness is controlled by the time of the hydrothermal process and thus the concentration of Zn ions in the solution. Furthermore, ZnGa2O4 nanotube arrays were obtained by depleting the GaN core from GaN-ZnGa2O4 core-shell nanowire arrays during the reaction and subsequent etching with HCl. The GaN-ZnGa2O4 core-shell nanowires exhibit photoluminescence peaks centered at 2.60 and 2.90 eV attributed to the ZnGa2O4 shell, as well as peaks centered at 3.35 and 3.50 eV corresponding to the GaN core. We also demonstrate the synthesis of GaN-ZnGa2O4 heterojunction nanowires by a selective formation process as a simple route toward development of heterojunction nanodevices for optoelectronic applications.

Piezo-phototronic effect enhanced photo-detector based on ZnO nano-arrays/NiO structure

NASA Astrophysics Data System (ADS)

Sun, Jingchang; Li, Peida; Gao, Ruixue; Lu, Xue; Li, Chengren; Lang, Yueyi; Zhang, Xiwen; Bian, Jiming

2018-01-01

A photo-detector with n-ZnO nano-arrays/p-NiO film structure was synthesized on flexible Ni foil substrate. In contrast to conventional detectors that detect only the photon energies greater than the band gap of working materials, the visible light with smaller photon energies (3.0 eV) than the band gap of both ZnO (3.3 eV) and NiO (3.7 eV) can be sensitively detected by this detector due to the spatially indirect type-II transition between ZnO nano-arrays and NiO film. The increase in output currents of the photo-detector with illumination density was observed at both forward and reverse bias, and it can be further enhanced by exerting external compressive strain along the c axis of ZnO nano-arrays by piezo-phototronic effect. A maximum enhancement of 1020% of the responsivity (R) was achieved under external compressive strain. The similar behaviors were demonstrated at four different excitation wavelengths (325, 365, 388 and 405 nm), providing compelling evidence that the responses performance of the photo-detector can be effectively enhanced using piezo-phototronic effect. Moreover, the piezo-phototronic effect enhanced performance can be well elucidated by the corresponding energy band diagram.

Carbon nanotube collimator fabrication and application

DOEpatents

Chow, Lee; Chai, Guangyu; Schenkel, Thomas

2010-07-06

Apparatus, methods, systems and devices for fabricating individual CNT collimators. Micron size fiber coated CNT samples are synthesized with chemical vapor deposition method and then the individual CNT collimators are fabricated with focused ion beam technique. Unfocused electron beams are successfully propagated through the CNT collimators. The CNT nano-collimators are used for applications including single ion implantation and in high-energy physics, and allow rapid, reliable testing of the transmission of CNT arrays for transport of molecules.

MoSe2 modified TiO2 nanotube arrays with superior photoelectrochemical performance

NASA Astrophysics Data System (ADS)

Zhang, Yaping; Zhu, Haifeng; Yu, Lianqing; He, Jiandong; Huang, Chengxing

2018-04-01

TiO2 nanotube arrays (TNTs) are first prepared by anodization Ti foils in ethylene glycol electrolyte. Then, MoSe2 deposites electrochemically on TNTs. The as-synthesized MoSe2/TiO2 composite has a much higher photocurrent density of 1.07 mA cm‑2 at 0 V than pure TNTs of 0.38 mA cm‑2, which suggests that the MoSe2/TiO2 composite film has optimum photoelectrocatalysis properties. The electron transport resistances of the MoSe2/TiO2 decreases to half of pure TiO2, at 295.6 ohm/cm2. Both photocurrent-time and Mott-Schottky plots indicate MoSe2 a p-type semiconductor characteristics. MoSe2/TiO2 composite can achieve a maximum 5 orders of magnitude enhancement in carrier density (4.650 × 1027 cm‑3) than that of pure TiO2 arrays. It can be attributed to p-n heterojunction formed between MoSe2 and TiO2, and the composite can be potentially applied in photoelectrochemical, photocatalysis fields.

Effect of Size-Dependent Thermal Instability on Synthesis of Zn2 SiO4-SiOx Core–Shell Nanotube Arrays and Their Cathodoluminescence Properties

PubMed Central

2010-01-01

Vertically aligned Zn2SiO4-SiOx(x < 2) core–shell nanotube arrays consisting of Zn2SiO4-nanoparticle chains encapsulated into SiOx nanotubes and SiOx-coated Zn2SiO4 coaxial nanotubes were synthesized via one-step thermal annealing process using ZnO nanowire (ZNW) arrays as templates. The appearance of different nanotube morphologies was due to size-dependent thermal instability and specific melting of ZNWs. With an increase in ZNW diameter, the formation mechanism changed from decomposition of “etching” to Rayleigh instability and then to Kirkendall effect, consequently resulting in polycrystalline Zn2SiO4-SiOx coaxial nanotubes, single-crystalline Zn2SiO4-nanoparticle-chain-embedded SiOx nanotubes, and single-crystalline Zn2SiO4-SiOx coaxial nanotubes. The difference in spatially resolved optical properties related to a particular morphology was efficiently documented by means of cathodoluminescence (CL) spectroscopy using a middle-ultraviolet emission at 310 nm from the Zn2SiO4 phase. PMID:20672064

Electrodeposition synthesis of MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposites and their visible light photocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Xuyao; Zhou, Xiaosong, E-mail: zxs801213@163.com; Li, Xiaoyu, E-mail: lixiaoyu@iga.ac.cn

2014-11-15

Highlights: • MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposites are prepared by electrodeposition. • MnO{sub 2}/TiO{sub 2} exhibits high visible light photocatalytic activity. • The results of XRD show the depositions are attributed to α-MnO{sub 2}. • A photocatalytic mechanism is discussed under visible light irradiation. - Abstract: MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposite photocatalysts have been synthesized through an electrodeposition method. X-ray powder diffraction analysis and X-ray photoelectron spectroscopy measurements reveal that the products of electrodeposition method are MnO{sub 2}. Scanning electron microscopy measurements suggest that the depositions are deposited on the surface or internal of the nanotube. UV–vis lightmore » absorbance spectra demonstrate the excellent adsorption properties of MnO{sub 2}/TiO{sub 2} over the whole region of visible light, which enables this novel photocatalytic material to possess remarkable activity in the photocatalytic degradation of acid Orange II under visible light radiation. Moreover, a possible photocatalytic mechanism is discussed.« less

Liquid-phase synthesis of vertically aligned carbon nanotubes and related nanomaterials on preheated alloy substrates

NASA Astrophysics Data System (ADS)

Yamagiwa, Kiyofumi

2018-02-01

Carbon nanotubes (CNTs) and related nanocarbons were selectively synthesized on commercially available alloy substrates by a simple liquid-phase technique. Fe- and Ni-rich stainless-steel (JIS SUS316L and Inconel®600, respectively) and Ni-Cu alloy (Monel®400) substrates were used for the synthesis, and each substrate was preheated in air to promote the self-formation of catalyst nanolayers on the surface. The substrates were resistance heated in ethanol without any addition of catalysts to grow CNTs. The yield of the CNTs effectively increased when the preheating process was employed. Highly aligned CNT arrays grew on the SUS316L substrate, while non-aligned CNTs and distinctive twisted fibers were observed on the other substrates. An Fe oxide layer was selectively formed on the preheated SUS316L substrate promoting the growth of the CNT arrays. Characterizations including cyclic voltammetry for the arrays revealed that the CNTs possess a comparatively defect-rich surface, which is a desirable characteristic for its application such as electrode materials for capacitors.

Construction of porous CuCo2S4 nanorod arrays via anion exchange for high-performance asymmetric supercapacitor.

PubMed

Cheng, Siyi; Shi, Tielin; Chen, Chen; Zhong, Yan; Huang, Yuanyuan; Tao, Xiangxu; Li, Junjie; Liao, Guanglan; Tang, Zirong

2017-07-27

To push the energy density limit of supercapacitors, proper pseudocapacitive materials with favorable nanostructures are urgently pursued. Ternary transition metal sulfides are promising electrode materials due to the better conductivity and higher electrochemical activity in comparison to the single element sulfides and transition metal oxides. In this work, we have successfully synthesized porous CuCo 2 S 4 nanorod array (NRAs) on carbon textile through a stepwise hydrothermal method, including the growth of the Cu-Co precursor nanowire arrays and subsequent conversion into CuCo 2 S 4 NRAs via anion exchange reaction. The CuCo 2 S 4 NRAs electrode exhibits a greatly enhanced specific capacitance and an outstanding cycling stability. Moreover, an asymmetric supercapacitor using the CuCo 2 S 4 NRAs as positive electrode and activated carbon as negative electrode delivers a high energy density of 56.96 W h kg -1 . Such superior performance demonstrate that the CuCo 2 S 4 NRAs are promising materials for future energy storage applications.

Titanium plate supported MoS2 nanosheet arrays for supercapacitor application

NASA Astrophysics Data System (ADS)

Wang, Lina; Ma, Ying; Yang, Min; Qi, Yanxing

2017-02-01

A promising new concept is to apply binder-free supercapacitor electrode by directly growing active materials on current collectors. However, there are many challenges to be solved, such as fabrication of well quality electronic contact and good mechanical stability films through a simple and feasible method. In this study, MoS2 nanosheet arrays supported on titanium plate has been synthesized by a hydrothermal method without other additives, surface active agents and toxic reagents. As the supercapacitor electrode, a good capacitance of 133 F g-1 is attained at a discharge current density of 1 A g-1. The specific energy density is 11.11 Wh kg-1 at a power density of 0.53 kW kg-1. Moreover, the electrode shows an excellent cyclic stability. The loss of capacity is only 7% even after 1000 cycles. In addition, the formation mechanism is proposed. The facile method of fabricating MoS2 nanosheet arrays on titanium plate affords an green and effective way to prepare other metal sulfides for the application in electrochemical capacitors.

Plasmonic resonances in hybrid systems of aluminum nanostructured arrays and few layer graphene within the UV-IR spectral range

NASA Astrophysics Data System (ADS)

González-Campuzano, R.; Saniger, J. M.; Mendoza, D.

2017-11-01

The size-controllable and ordered Al nanocavities and nanodomes arrays were synthesized by electrochemical anodization of aluminum using phosphoric acid, citric acid and mixture both acids. Few layer graphene (FLG) was transferred directly on top of Al nanostructures and their morphology were evaluated by scanning electron microscopy. The interaction between FLG and the plasmonic properties of Al nanostructures arrays were investigated based on specular reflectivity in the ultraviolet-visible-infrared range and Raman spectroscopy. We found that their optical reflectivity was dramatically reduced as compared with unstructured Al. At the same time pronounced reflectivity dips were detectable in the 200-896 nm wavelength range, which were ascribed to plasmonic resonances. The plasmonic properties of these nanostructures do not exhibit evident changes by the presence of FLG in the UV-vis range of the electromagnetic spectrum. By contrast, the surface-enhanced Raman spectroscopy of FLG was observed in nanocavities and nanodomes structures that result in an intensity increase of the characteristic G and 2D bands of FLG induced by the plasmonic properties of Al nanostructures.

Preparation and UV-Vis photodegradation of gaseous benzene by TiO2 nanotube arrays supporting V2O5 nanoparticles

NASA Astrophysics Data System (ADS)

Zhao, Chunxia; Song, Yanbao; Yang, Yunxia; Chen, Wen; Li, Xiaoyu; Wang, Zongsheng

2015-07-01

TiO2-based catalysts effective in visible radiation for eliminating organic pollutants have attracted intense research activity as a future generation photocatalytic material. However, recombination of electron-hole pairs through trapping/de-trapping as well as the disadvantages of recycling and separation/filtration of powders lead to the limitation of powder TiO2 materials. TiO2 nanotube array films supporting vanadium pentoxide nanoparticles (VTNTs) were synthesized by electrophoresis deposition method with the prepared TiO2 nanotube arrays as the cathode and V2O5 sol as the electrolyte. The results indicate that the formation of Ti-O-V bonds and intimate interaction between host-guest interfaces help to enhance the hybrids’ photodegradation activity of gaseous benzene. Importantly, hybrid film catalysts prepared with 0.05 mol/L V2O5 sol for 10 min electrophoresis deposition perform a 98% conversion rate of benzene and 1028.8 mg/m3CO2 production in 80 min under UV-Vis irradiation.

Design of Pd/PANI/Pd sandwich-structured nanotube array catalysts with special shape effects and synergistic effects for ethanol electrooxidation.

PubMed

Wang, An-Liang; Xu, Han; Feng, Jin-Xian; Ding, Liang-Xin; Tong, Ye-Xiang; Li, Gao-Ren

2013-07-24

Low cost, high activity, and long-term durability are the main requirements for commercializing fuel cell electrocatalysts. Despite tremendous efforts, developing non-Pt anode electrocatalysts with high activity and long-term durability at low cost remains a significant technical challenge. Here we report a new type of hybrid Pd/PANI/Pd sandwich-structured nanotube array (SNTA) to exploit shape effects and synergistic effects of Pd-PANI composites for the oxidation of small organic molecules for direct alcohol fuel cells. These synthesized Pd/PANI/Pd SNTAs exhibit significantly improved electrocatalytic activity and durability compared with Pd NTAs and commercial Pd/C catalysts. The unique SNTAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Besides the merits of nanotube arrays, the improved electrocatalytic activity and durability are especially attributed to the special Pd/PANI/Pd sandwich-like nanostructures, which results in electron delocalization between Pd d orbitals and PANI π-conjugated ligands and in electron transfer from Pd to PANI.

Hierarchical nanorods constructed by Mn2Mo3O8@reduced graphene oxide nanosheet arrays with enhanced lithium storage properties

NASA Astrophysics Data System (ADS)

Zhang, Lifeng; Shen, Kechao; He, Wenjie; Liu, Yi; Yin, Lixiong; Guo, Shouwu

2018-10-01

3D hierarchical nanorods of Mn2Mo3O8@reduced graphene oxide (rGO) nanohybrid assembled with nanosheet arrays have been fabricated via a facile solvothermal process combined with subsequent anneal. It is identified that the annealing temperature and the input amount of graphene oxide (GO) are critical to form such unique Mn2Mo3O8@rGO nanostructure, whose hierarchical nanorods (ca. 470 nm of diameter) are constructed by vertical nanosheet arrays (30 ± 5 nm average thickness for individual nanosheet). As an anode material for lithium ion batteries, the hierarchical Mn2Mo3O8@rGO electrode delivers superior capability and rate properties to the compared nanostructure synthesized at different annealing temperature. The enhanced electrochemical performance is attributed to the rational combination of 3D nanorods and 2D nanosheets, which is beneficial to the fast penetration of electrolytes and thus provide more reactive facets, shorten the diffusion paths of Li+ and facilitate the electron conduction.

Three-Dimensional Porous Iron Vanadate Nanowire Arrays as a High-Performance Lithium-Ion Battery.

PubMed

Cao, Yunhe; Fang, Dong; Liu, Ruina; Jiang, Ming; Zhang, Hang; Li, Guangzhong; Luo, Zhiping; Liu, Xiaoqing; Xu, Jie; Xu, Weilin; Xiong, Chuanxi

2015-12-23

Development of three-dimensional nanoarchitectures on current collectors has emerged as an effective strategy for enhancing rate capability and cycling stability of the electrodes. Herein, a new type of three-dimensional porous iron vanadate (Fe0.12V2O5) nanowire arrays on a Ti foil has been synthesized by a hydrothermal method. The as-prepared Fe0.12V2O5 nanowires are about 30 nm in diameter and several micrometers in length. The effect of reaction time on the resulting morphology is investigated and the mechanism for the nanowire formation is proposed. As an electrode material used in lithium-ion batteries, the unique configuration of the Fe0.12V2O5 nanowire arrays presents enhanced capacitance, satisfying rate capability and good cycling stability, as evaluated by cyclic voltammetry and galvanostatic discharge-charge cycling. It delivers a high discharge capacity of 293 mAh·g(-1) at 2.0-3.6 V or 382.2 mAh·g(-1) at 1.0-4.0 V after 50 cycles at 30 mA·g(-1).

Evolution of the composition, structure, and piezoelectric performance of (K1-xNax)NbO3 nanorod arrays with hydrothermal reaction time

NASA Astrophysics Data System (ADS)

Jin, Wenchao; Wang, Zhao; Li, Meng; He, Yahua; Hu, Xiaokang; Li, Luying; Gao, Yihua; Hu, Yongming; Gu, Haoshuang; Wang, Xiaolin

2018-04-01

Lead-free (K,Na)NbO3 (KNN) nanorod arrays were synthesized with the assistance of a Nb: SrTiO3 single-crystal substrate through the hydrothermal process. The evolutions of the morphology, composition, and structure of the as-synthesized KNN nanorods with the increase in reaction time were investigated. The results confirmed that the increase in reaction time up to 3 h led to the increase in the length and aspect ratio of the well-aligned KNN nanorods. All samples have K-rich orthorhombic crystal structures, while the diffraction peaks shifted towards a higher degree. The peak shifts should be attributed to the increase in the Na content in the KNN lattice, which could decrease the lattice parameters owing to the small ionic radius of Na+ than that of K+. Moreover, the increase in reaction time also resulted in the suppression of oxygen vacancies on the surface of the KNN nanorods. These evolutions of the composition and crystal structure, as well as the decrease in the defect content, lead to great enhancement of the nanorod's piezoelectric response, as their d33 value was increased from 19 to 64 pm/V. These results demonstrated the significant impact of reaction time on the hydrothermal growth of high-performance lead-free KNN one-dimensional nanomaterials.

Original 2-(3-Alkoxy-1H-pyrazol-1-yl)azines Inhibitors of Human Dihydroorotate Dehydrogenase (DHODH)

PubMed Central

2016-01-01

Following our discovery of human dihydroorotate dehydrogenase (DHODH) inhibition by 2-(3-alkoxy-1H-pyrazol-1-yl)pyrimidine derivatives as well as 2-(4-benzyl-3-ethoxy-5-methyl-1H-pyrazol-1-yl)-5-methylpyridine, we describe here the syntheses and evaluation of an array of azine-bearing analogues. As in our previous report, the structure–activity study of this series of human DHODH inhibitors was based on a phenotypic assay measuring measles virus replication. Among other inhibitors, this round of syntheses and biological evaluation iteration led to the highly active 5-cyclopropyl-2-(4-(2,6-difluorophenoxy)-3-isopropoxy-5-methyl-1H-pyrazol-1-yl)-3-fluoropyridine. Inhibition of DHODH by this compound was confirmed in an array of in vitro assays, including enzymatic tests and cell-based assays for viral replication and cellular growth. This molecule was found to be more active than the known inhibitors of DHODH, brequinar and teriflunomide, thus opening perspectives for its use as a tool or for the design of an original series of immunosuppressive agent. Moreover, because other series of inhibitors of human DHODH have been found to also affect Plasmodium falciparum DHODH, all the compounds were assayed for their effect on P. falciparum growth. However, the modest in vitro inhibition solely observed for two compounds did not correlate with their inhibition of P. falciparum DHODH. PMID:26079043

Hierarchical Co-based Porous Layered Double Hydroxide Arrays Derived via Alkali Etching for High-performance Supercapacitors

NASA Astrophysics Data System (ADS)

Abushrenta, Nasser; Wu, Xiaochao; Wang, Junnan; Liu, Junfeng; Sun, Xiaoming

2015-08-01

Hierarchical nanoarchitecture and porous structure can both provide advantages for improving the electrochemical performance in energy storage electrodes. Here we report a novel strategy to synthesize new electrode materials, hierarchical Co-based porous layered double hydroxide (PLDH) arrays derived via alkali etching from Co(OH)2@CoAl LDH nanoarrays. This structure not only has the benefits of hierarchical nanoarrays including short ion diffusion path and good charge transport, but also possesses a large contact surface area owing to its porous structure which lead to a high specific capacitance (23.75 F cm-2 or 1734 F g-1 at 5 mA cm-2) and excellent cycling performance (over 85% after 5000 cycles). The enhanced electrode material is a promising candidate for supercapacitors in future application.

Hierarchical Co-based Porous Layered Double Hydroxide Arrays Derived via Alkali Etching for High-performance Supercapacitors

PubMed Central

Abushrenta, Nasser; Wu, Xiaochao; Wang, Junnan; Liu, Junfeng; Sun, Xiaoming

2015-01-01

Hierarchical nanoarchitecture and porous structure can both provide advantages for improving the electrochemical performance in energy storage electrodes. Here we report a novel strategy to synthesize new electrode materials, hierarchical Co-based porous layered double hydroxide (PLDH) arrays derived via alkali etching from Co(OH)2@CoAl LDH nanoarrays. This structure not only has the benefits of hierarchical nanoarrays including short ion diffusion path and good charge transport, but also possesses a large contact surface area owing to its porous structure which lead to a high specific capacitance (23.75 F cm−2 or 1734 F g−1 at 5 mA cm−2) and excellent cycling performance (over 85% after 5000 cycles). The enhanced electrode material is a promising candidate for supercapacitors in future application. PMID:26278334

Double-side illuminated titania nanotubes for high volume hydrogen generation by water splitting

NASA Astrophysics Data System (ADS)

Mohapatra, Susanta K.; Mahajan, Vishal K.; Misra, Mano

2007-11-01

A sonoelectrochemical anodization method is proposed to synthesize TiO2 nanotubular arrays on both sides of a titanium foil (TiO2/Ti/TiO2). Highly ordered TiO2 nanotubular arrays of 16 cm2 area with uniform surface distribution can be obtained using this anodization procedure. These double-sided TiO2/Ti/TiO2 materials are used as both photoanode (carbon-doped titania nanotubes) and cathode (Pt nanoparticles dispersed on TiO2 nanotubes; PtTiO2/Ti/PtTiO2) in a specially designed photoelectrochemical cell to generate hydrogen by water splitting at a rate of 38 ml h-1. The nanomaterials are characterized by FESEM, HRTEM, STEM, EDS, FFT, SAED and XPS techniques. The present approach can be used for large-scale hydrogen generation using renewable energy sources.

A coherent through-wall MIMO phased array imaging radar based on time-duplexed switching

NASA Astrophysics Data System (ADS)

Chen, Qingchao; Chetty, Kevin; Brennan, Paul; Lok, Lai Bun; Ritchie, Matthiew; Woodbridge, Karl

2017-05-01

Through-the-Wall (TW) radar sensors are gaining increasing interest for security, surveillance and search and rescue applications. Additionally, the integration of Multiple-Input, Multiple-Output (MIMO) techniques with phased array radar is allowing higher performance at lower cost. In this paper we present a 4-by-4 TW MIMO phased array imaging radar operating at 2.4 GHz with 200 MHz bandwidth. To achieve high imaging resolution in a cost-effective manner, the 4 Tx and 4 Rx elements are used to synthesize a uniform linear array (ULA) of 16 virtual elements. Furthermore, the transmitter is based on a single-channel 4-element time-multiplexed switched array. In transmission, the radar utilizes frequency modulated continuous wave (FMCW) waveforms that undergo de-ramping on receive to allow digitization at relatively low sampling rates, which then simplifies the imaging process. This architecture has been designed for the short-range TW scenarios envisaged, and permits sufficient time to switch between antenna elements. The paper first outlines the system characteristics before describing the key signal processing and imaging algorithms which are based on traditional Fast Fourier Transform (FFT) processing. These techniques are implemented in LabVIEW software. Finally, we report results from an experimental campaign that investigated the imaging capabilities of the system and demonstrated the detection of personnel targets. Moreover, we show that multiple targets within a room with greater than approximately 1 meter separation can be distinguished from one another.

Direct electrodeposition of gold nanotube arrays of rough and porous wall by cyclic voltammetry and its applications of simultaneous determination of ascorbic acid and uric acid.

PubMed

Yang, Guangming; Li, Ling; Jiang, Jinhe; Yang, Yunhui

2012-08-01

Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02×10(-7)-5.23×10(-4) mol L(-1) and 1.43×10(-7)-4.64×10(-4) mol L(-1), the detection limits were 1.12×10(-8) mol L(-1) and 2.24×10(-8) mol L(-1), respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. Copyright © 2012 Elsevier B.V. All rights reserved.

Aerosol jet printed silver nanowire transparent electrode for flexible electronic application

NASA Astrophysics Data System (ADS)

Tu, Li; Yuan, Sijian; Zhang, Huotian; Wang, Pengfei; Cui, Xiaolei; Wang, Jiao; Zhan, Yi-Qiang; Zheng, Li-Rong

2018-05-01

Aerosol jet printing technology enables fine feature deposition of electronic materials onto low-temperature, non-planar substrates without masks. In this work, silver nanowires (AgNWs) are proposed to be printed into transparent flexible electrodes using a Maskless Mesoscale Material Deposition Aerosol Jet® printing system on a glass substrate. The influence of the most significant process parameters, including printing cycles, printing speed, and nozzle size, on the performance of AgNW electrodes was systematically studied. The morphologies of printed patterns were characterized by scanning electron microscopy, and the transmittance was evaluated using an ultraviolet-visible spectrophotometer. Under optimum conditions, high transparent AgNW electrodes with a sheet resistance of 57.68 Ω/sq and a linewidth of 50.9 μm were obtained, which is an important step towards a higher performance goal for flexible electronic applications.

Method and system using power modulation for maskless vapor deposition of spatially graded thin film and multilayer coatings with atomic-level precision and accuracy

DOEpatents

Montcalm, Claude [Livermore, CA; Folta, James Allen [Livermore, CA; Tan, Swie-In [San Jose, CA; Reiss, Ira [New City, NY

2002-07-30

A method and system for producing a film (preferably a thin film with highly uniform or highly accurate custom graded thickness) on a flat or graded substrate (such as concave or convex optics), by sweeping the substrate across a vapor deposition source operated with time-varying flux distribution. In preferred embodiments, the source is operated with time-varying power applied thereto during each sweep of the substrate to achieve the time-varying flux distribution as a function of time. A user selects a source flux modulation recipe for achieving a predetermined desired thickness profile of the deposited film. The method relies on precise modulation of the deposition flux to which a substrate is exposed to provide a desired coating thickness distribution.

Humidity Sensing Properties of Paper Substrates and Their Passivation with ZnO Nanoparticles for Sensor Applications

PubMed Central

Niarchos, Georgios; Dubourg, Georges; Afroudakis, Georgios; Georgopoulos, Markos; Tsouti, Vasiliki; Makarona, Eleni; Crnojevic-Bengin, Vesna; Tsamis, Christos

2017-01-01

In this paper, we investigated the effect of humidity on paper substrates and propose a simple and low-cost method for their passivation using ZnO nanoparticles. To this end, we built paper-based microdevices based on an interdigitated electrode (IDE) configuration by means of a mask-less laser patterning method on simple commercial printing papers. Initial resistive measurements indicate that a paper substrate with a porous surface can be used as a cost-effective, sensitive and disposable humidity sensor in the 20% to 70% relative humidity (RH) range. Successive spin-coated layers of ZnO nanoparticles then, control the effect of humidity. Using this approach, the sensors become passive to relative humidity changes, paving the way to the development of ZnO-based gas sensors on paper substrates insensitive to humidity. PMID:28273847

Rhodium-Catalyzed Asymmetric Conjugate Alkynylation/Aldol Cyclization Cascade for the Formation of α-Propargyl-β-hydroxyketones.

PubMed

Choo, Ken-Loon; Lautens, Mark

2018-03-02

A rhodium-catalyzed conjugate alkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)-C(sp 3 ) bond, a C(sp 3 )-C(sp 3 ) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic utility of the newly installed alkynyl moiety was exhibited by subjecting the products to an array of derivatizations.

Fly-By-Light/Power-By-Wire Fault-Tolerant Fiber-Optic Backplane

NASA Technical Reports Server (NTRS)

Malekpour, Mahyar R.

2002-01-01

The design and development of a fault-tolerant fiber-optic backplane to demonstrate feasibility of such architecture is presented. The simulation results of test cases on the backplane in the advent of induced faults are presented, and the fault recovery capability of the architecture is demonstrated. The architecture was designed, developed, and implemented using the Very High Speed Integrated Circuits (VHSIC) Hardware Description Language (VHDL). The architecture was synthesized and implemented in hardware using Field Programmable Gate Arrays (FPGA) on multiple prototype boards.

Controlled growth of ordered nanopore arrays in GaN.

PubMed

Wildeson, Isaac H; Ewoldt, David A; Colby, Robert; Stach, Eric A; Sands, Timothy D

2011-02-09

High-quality, ordered nanopores in semiconductors are attractive for numerous biological, electrical, and optical applications. Here, GaN nanorods with continuous pores running axially through their centers were grown by organometallic vapor phase epitaxy. The porous nanorods nucleate on an underlying (0001)-oriented GaN film through openings in a SiN(x) template that are milled by a focused ion beam, allowing direct placement of porous nanorods. Nanopores with diameters ranging from 20-155 nm were synthesized with crystalline sidewalls.

Vertically aligned ZnO nanorod core-polypyrrole conducting polymer sheath and nanotube arrays for electrochemical supercapacitor energy storage

PubMed Central

2014-01-01

Nanocomposite electrodes having three-dimensional (3-D) nanoscale architecture comprising of vertically aligned ZnO nanorod array core-polypyrrole (PPy) conducting polymer sheath and the vertical PPy nanotube arrays have been investigated for supercapacitor energy storage. The electrodes in the ZnO nanorod core-PPy sheath structure are formed by preferential nucleation and deposition of PPy layer over hydrothermally synthesized vertical ZnO nanorod array by controlled pulsed current electropolymerization of pyrrole monomer under surfactant action. The vertical PPy nanotube arrays of different tube diameter are created by selective etching of the ZnO nanorod core in ammonia solution for different periods. Cyclic voltammetry studies show high areal-specific capacitance approximately 240 mF.cm-2 for open pore and approximately 180 mF.cm-2 for narrow 30-to-36-nm diameter PPy nanotube arrays attributed to intensive faradic processes arising from enhanced access of electrolyte ions through nanotube interior and exterior. Impedance spectroscopy studies show that capacitive response extends over larger frequency domain in electrodes with PPy nanotube structure. Simulation of Nyquist plots by electrical equivalent circuit modeling establishes that 3-D nanostructure is better represented by constant phase element which accounts for the inhomogeneous electrochemical redox processes. Charge-discharge studies at different current densities establish that kinetics of the redox process in PPy nanotube electrode is due to the limitation on electron transport rather than the diffusive process of electrolyte ions. The PPy nanotube electrodes show deep discharge capability with high coulomb efficiency and long-term charge-discharge cyclic studies show nondegrading performance of the specific areal capacitance tested for 5,000 cycles. PMID:25246867

High-Performance 2.6 V Aqueous Asymmetric Supercapacitors based on In Situ Formed Na0.5 MnO2 Nanosheet Assembled Nanowall Arrays.

PubMed

Jabeen, Nawishta; Hussain, Ahmad; Xia, Qiuying; Sun, Shuo; Zhu, Junwu; Xia, Hui

2017-08-01

The voltage limit for aqueous asymmetric supercapacitors is usually 2 V, which impedes further improvement in energy density. Here, high Na content Birnessite Na 0.5 MnO 2 nanosheet assembled nanowall arrays are in situ formed on carbon cloth via electrochemical oxidation. It is interesting to find that the electrode potential window for Na 0.5 MnO 2 nanowall arrays can be extended to 0-1.3 V (vs Ag/AgCl) with significantly increased specific capacitance up to 366 F g -1 . The extended potential window for the Na 0.5 MnO 2 electrode provides the opportunity to further increase the cell voltage of aqueous asymmetric supercapacitors beyond 2 V. To construct the asymmetric supercapacitor, carbon-coated Fe 3 O 4 nanorod arrays are synthesized as the anode and can stably work in a negative potential window of -1.3 to 0 V (vs Ag/AgCl). For the first time, a 2.6 V aqueous asymmetric supercapacitor is demonstrated by using Na 0.5 MnO 2 nanowall arrays as the cathode and carbon-coated Fe 3 O 4 nanorod arrays as the anode. In particular, the 2.6 V Na 0.5 MnO 2 //Fe 3 O 4 @C asymmetric supercapacitor exhibits a large energy density of up to 81 Wh kg -1 as well as excellent rate capability and cycle performance, outperforming previously reported MnO 2 -based supercapacitors. This work provides new opportunities for developing high-voltage aqueous asymmetric supercapacitors with further increased energy density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoresponsive peptide azobenzene conjugates that specifically interact with platinum surfaces

NASA Astrophysics Data System (ADS)

Dinçer, S.; Tamerler, C.; Sarıkaya, M.; Pişkin, E.

2008-05-01

The aim of this study is to prepare photoresponsive peptide-azobenzene compounds which interacts with platinum surfaces specifically, in order to create smart surfaces for further novel applications in design of smart biosensors and array platforms. Here, a water-soluble azobenzene molecule, 4-hydroxyazo benzene,4-sulfonic acid was synthesized by diazo coupling reaction. A platinum-specific peptide, originally selected by a phage display technique was chemically synthesized/purchased, and conjugated with the azobenzene compound activated with carbonyldiimidazole. Both azobenzene and its conjugate were characterized (including photoresponsive properties) by FTIR, NMR, and UV-spectrophotometer. The yield of conjugation reaction estimated by ninhydrin assay was about 65%. Peptide incorporation did not restrict the light-sensitivity of azobenzene. Adsorption of both the peptide and its azobenzene conjugate was followed by Quartz Crystal Microbalance (QCM) system. The kinetic evaluations exhibited that both molecules interact platinum surfaces, quite rapidly and strongly.

Synthesis of nanostructured bio-related materials by hybridization of synthetic polymers with polysaccharides or saccharide residues.

PubMed

Kaneko, Yoshiro; Kadokawa, Jun-Ichi

2006-01-01

In the first part of this review, we describe the synthesis of nanostructured hybrid materials composed of polysaccharides and synthetic polymers. Amylose-synthetic polymer inclusion complexes were synthesized by amylose-forming polymerization using phosphorylase enzyme in the presence of synthetic polymers such as polyethers and polyesters. Alginate-polymethacrylate hybrid materials were prepared by free-radical polymerization of cationic methacrylate in the presence of sodium alginate. These methods allow the simultaneous control of the nanostructure with polymerization, giving well-defined hybrid materials. In the second part of this review, we describe the synthesis of novel glycopolymers with rigid structures. Polyaniline-based glycopolymers were synthesized by means of oxidative polymerization of N-glycosylaniline. Polysiloxane-based glycopolymers were prepared by means of introduction of sugar-lactone to the rodlike polysiloxane. These glycopolymers had regular higher-ordered structures due to their rigid polymer backbones, resulting in control of the three-dimensional array of sugar-residues.

The composition of the primitive atmosphere and the synthesis of organic compounds on the early Earth

NASA Technical Reports Server (NTRS)

Bada, J. L.; Miller, S. L.

1985-01-01

The generally accepted theory for the origin of life on the Earth requires that a large variety of organic compounds be present to form the first living organisms and to provide the energy sources for primitive life either directly or through various fermentation reactions. This can provide a strong constraint on discussions of the formation of the Earth and on the composition of the primitive atmosphere. In order for substantial amounts of organic compounds to have been present on the prebiological Earth, certain conditions must have existed. There is a large body of literature on the prebiotic synthesis of organic compounds in various postulated atmospheres. In this mixture of abiotically synthesized organic compounds, the amino acids are of special interest since they are utilized by modern organisms to synthesize structural materials and a large array of catalytic peptides.

Adenosine Monophosphate Forms Ordered Arrays in Multilamellar Lipid Matrices: Insights into Assembly of Nucleic Acid for Primitive Life

PubMed Central

Toppozini, Laura; Dies, Hannah; Deamer, David W.; Rheinstädter, Maikel C.

2013-01-01

A fundamental question of biology is how nucleic acids first assembled and then were incorporated into the earliest forms of cellular life 4 billion years ago. The polymerization of nucleotides is a condensation reaction in which phosphodiester bonds are formed. This reaction cannot occur in aqueous solutions, but guided polymerization in an anhydrous lipid environment could promote a non-enzymatic condensation reaction in which oligomers of single stranded nucleic acids are synthesized. We used X-ray scattering to investigate 5′-adenosine monophosphate (AMP) molecules captured in a multilamellar phospholipid matrix composed of dimyristoylphosphatidylcholine. Bragg peaks corresponding to the lateral organization of the confined AMP molecules were observed. Instead of forming a random array, the AMP molecules are highly entangled, with the phosphate and ribose groups in close proximity. This structure may facilitate polymerization of the nucleotides into RNA-like polymers. PMID:23667523

Adenosine monophosphate forms ordered arrays in multilamellar lipid matrices: insights into assembly of nucleic acid for primitive life.

PubMed

Toppozini, Laura; Dies, Hannah; Deamer, David W; Rheinstädter, Maikel C

2013-01-01

A fundamental question of biology is how nucleic acids first assembled and then were incorporated into the earliest forms of cellular life 4 billion years ago. The polymerization of nucleotides is a condensation reaction in which phosphodiester bonds are formed. This reaction cannot occur in aqueous solutions, but guided polymerization in an anhydrous lipid environment could promote a non-enzymatic condensation reaction in which oligomers of single stranded nucleic acids are synthesized. We used X-ray scattering to investigate 5'-adenosine monophosphate (AMP) molecules captured in a multilamellar phospholipid matrix composed of dimyristoylphosphatidylcholine. Bragg peaks corresponding to the lateral organization of the confined AMP molecules were observed. Instead of forming a random array, the AMP molecules are highly entangled, with the phosphate and ribose groups in close proximity. This structure may facilitate polymerization of the nucleotides into RNA-like polymers.

Vertically-aligned BCN Nanotube Arrays with Superior Performance in Electrochemical capacitors

PubMed Central

Zhou, Junshuang; Li, Na; Gao, Faming; Zhao, Yufeng; Hou, Li; Xu, Ziming

2014-01-01

Electrochemical capacitors (EC) have received tremendous interest due to their high potential to satisfy the urgent demand in many advanced applications. The development of new electrode materials is considered to be the most promising approach to enhance the EC performance substantially. Herein, we present a high-capacity capacitor material based on vertically-aligned BC2N nanotube arrays (VA-BC2NNTAs) synthesized by low temperature solvothermal route. The obtained VA-BC2NNTAs display the good aligned nonbuckled tubular structure, which could indeed advantageously enhance capacitor performance. VA-BC2NNTAs exhibit an extremely high specific capacitance, 547 Fg−1, which is about 2–6 times larger than that of the presently available carbon-based materials. Meanwhile, VA-BC2NNTAs maintain an excellent rate capability and high durability. All these characteristics endow VA-BC2NNTAs an alternative promising candidate for an efficient electrode material for electrochemical capacitors (EC). PMID:25124300

Chemical Vapor Deposition for Ultra-lightweight Thin-film Solar Arrays for Space

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Raffaelle, Ryne P.; Banger, Kulbinder K.; Jin, Michael H.; Lau, Janice E.; Harris, Jerry D.; Cowen, Jonathan E.; Duraj, Stan A.

2002-01-01

The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. A key technical issues outlined in the 2001 U.S. Photovoltaic Roadmap, is the need to develop low cost, high throughput manufacturing for high-efficiency thin film solar cells. At NASA GRC we have focused on the development of new single-source-precursors (SSPs) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV devices.

Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors

DOE PAGES

Han, Catherine Y.; Xiao, Zhi-Li; Wang, H. Hau; ...

2009-01-01

We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbonmore » nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.« less

Patterned carbon nanotubes fabricated by the combination of microcontact printing and diblock copolymer micelles.

PubMed

Xu, Peng; Ji, Xin; Qi, Junlei; Yang, Hongmin; Zheng, Weitao; Abetz, Volker; Jiang, Shimei; Shen, Jiacong

2010-01-01

A convenient approach to synthesize patterned carbon nanotubes (CNTs) of three morphologies on printed substrates by combination of microcontact printing (microCP) and a plasma-enhanced chemical vapor deposition (PECVD) process is presented. Micelles of polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) in toluene were used as nanoreactors to fabricate FeCl3 in the core domains, and the complex solution was used as an ink to print films with polydimethylsiloxane (PDMS) stamps, different morphologies (porous, dots and stripes patterns) of the FeCl3-loaded micellar films were left onto silicon substrates after printed. After removing the polymer by thermal decomposition, the left iron oxide cluster arrays on the substrate were used as catalysts for the growth of CNTs by the process of PECVD, where the CNTs uniformly distributed on the substrates according to the morphologies of patterned catalysts arrays.

Conformal drug delivery and instantaneous monitoring based on an inverse synthesis method at a diagnostic ultrasound platform

NASA Astrophysics Data System (ADS)

Xu, Shanshan; Zong, Yujin; Liu, Xiaodong; Lu, Mingzhu; Wan, Mingxi

2017-03-01

In this paper, based on a programmable diagnostic ultrasound scanner, a combined approach was proposed, in which a variable-sized focal region wherein the acoustic pressure is above the ultrasound contrast agents (UCA) fragmentation threshold is synthesized by reasonably matching the excitation voltage and the transmit aperture of the linear array at 5MHz, the UCAs' temporal and spatial distribution before and after the microbubbles fragmentation is monitored using the plane-wave transmission and reception at 400Hz and, simultaneously, the broadband noise emission during the microbubbles fragmentation is extracted using the backscattering of focused release bursts (destruction pulse) themselves on the linear array. Then, acquired radio frequency (RF) data are processed to draw parameters which can be correlated with the indicator of broadband noise emission level, namely inertial cavitation dose (ICD) and microbubble fragmentation efficiency, namely decay rate of microbubbles.

A 45 ps time digitizer with a two-phase clock and dual-edge two-stage interpolation in a field programmable gate array device

NASA Astrophysics Data System (ADS)

Szplet, R.; Kalisz, J.; Jachna, Z.

2009-02-01

We present a time digitizer having 45 ps resolution, integrated in a field programmable gate array (FPGA) device. The time interval measurement is based on the two-stage interpolation method. A dual-edge two-phase interpolator is driven by the on-chip synthesized 250 MHz clock with precise phase adjustment. An improved dual-edge double synchronizer was developed to control the main counter. The nonlinearity of the digitizer's transfer characteristic is identified and utilized by the dedicated hardware code processor for the on-the-fly correction of the output data. Application of presented ideas has resulted in the measurement uncertainty of the digitizer below 70 ps RMS over the time interval ranging from 0 to 1 s. The use of the two-stage interpolation and a fast FIFO memory has allowed us to obtain the maximum measurement rate of five million measurements per second.

Effect of the polymeric coating thickness on the photocurrent performance of titanium dioxide nanorod arrays-polyaniline composite-based UV photosensor

NASA Astrophysics Data System (ADS)

Yusoff, M. M.; Mamat, M. H.; Malek, M. F.; Othman, , N.; Ismail, A. S.; Saidi, S. A.; Mohamed, R.; Suriani, A. B.; Khusaimi, Z.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) nanorod arrays (TNAs) were synthesized and deposited on fluorine tin oxide (FTO)-coated glass substrate using a one-step immersion method in a glass container. The effect of the polymeric coating thickness of p-type polyaniline (PANI) on the n-type TNAs was investigated in the p-n heterojunction photodiode (PD) for the application of ultraviolet (UV) photosensor. The fabricated photosensor demonstrated an increased photocurrent under UV irradiation in correlation with the thickness layer of PANI. The measured UV response showed the highest photocurrent of 0.014 µA at 1.0 V of reverse bias with low dark current under the UV radiation (365 nm, 750 µW/cm2). The thickness of the PANI film improved the photocurrent of the fabricated TNAs/PANI composite-based UV photosensor.

Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor

NASA Astrophysics Data System (ADS)

Wu, Di; Lou, Zhenhua; Wang, Yuange; Xu, Tingting; Shi, Zhifeng; Xu, Junmin; Tian, Yongtao; Li, Xinjian

2017-10-01

Few-layer MoS2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS2/Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS2/SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS2-based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ˜50% RH), with good repeatability and selectivity of the MoS2/SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS2/SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

Synthesis of p-type nickel oxide nanosheets on n-type titanium dioxide nanorod arrays for p-n heterojunction-based UV photosensor

NASA Astrophysics Data System (ADS)

Yusoff, M. M.; Mamat, M. H.; Malek, M. F.; Abdullah, M. A. R.; Ismail, A. S.; Saidi, S. A.; Mohamed, R.; Suriani, A. B.; Khusaimi, Z.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) nanorod arrays (TNAs) were synthesized and deposited on fluorine tin oxide (FTO)-coated glass substrate using a novel and facile immersion method in a glass container. The synthesis and deposition of p-type nickel oxide (NiO) nanosheets (NS) on the n-type TNAs was investigated in the p-n heterojunction photodiode (PD) for the application of ultraviolet (UV) photosensor. The fabricated TNAs/NiO NS based UV photosensor exhibited a highly increased photocurrent of 4.3 µA under UV radiation (365 nm, 750 µW/cm2) at 1.0 V reverse bias. In this study, the fabricated TNAs/NiO NS p-n heterojunction based photodiode showed potential applications for UV photosensor based on the stable photo-generated current attained under UV radiation.

Nanobiodevices for Biomolecule Analysis and Imaging

NASA Astrophysics Data System (ADS)

Yasui, Takao; Kaji, Noritada; Baba, Yoshinobu

2013-06-01

Nanobiodevices have been developed to analyze biomolecules and cells for biomedical applications. In this review, we discuss several nanobiodevices used for disease-diagnostic devices, molecular imaging devices, regenerative medicine, and drug-delivery systems and describe the numerous advantages of nanobiodevices, especially in biological, medical, and clinical applications. This review also outlines the fabrication technologies for nanostructures and nanomaterials, including top-down nanofabrication and bottom-up molecular self-assembly approaches. We describe nanopillar arrays and nanowall arrays for the ultrafast separation of DNA or protein molecules and nanoball materials for the fast separation of a wide range of DNA molecules, and we present examples of applications of functionalized carbon nanotubes to obtain information about subcellular localization on the basis of mobility differences between free fluorophores and fluorophore-labeled carbon nanotubes. Finally, we discuss applications of newly synthesized quantum dots to the screening of small interfering RNA, highly sensitive detection of disease-related proteins, and development of cancer therapeutics and diagnostics.

In Situ Synthesis of Vertical Standing Nanosized NiO Encapsulated in Graphene as Electrodes for High-Performance Supercapacitors.

PubMed

Lin, Jinghuang; Jia, Henan; Liang, Haoyan; Chen, Shulin; Cai, Yifei; Qi, Junlei; Qu, Chaoqun; Cao, Jian; Fei, Weidong; Feng, Jicai

2018-03-01

NiO is a promising electrode material for supercapacitors. Herein, the novel vertically standing nanosized NiO encapsulated in graphene layers (G@NiO) are rationally designed and synthesized as nanosheet arrays. This unique vertical standing structure of G@NiO nanosheet arrays can enlarge the accessible surface area with electrolytes, and has the benefits of short ion diffusion path and good charge transport. Further, an interconnected graphene conductive network acts as binder to encapsulate the nanosized NiO particles as core-shell structure, which can promote the charge transport and maintain the structural stability. Consequently, the optimized G@NiO hybrid electrodes exhibit a remarkably enhanced specific capacity up to 1073 C g -1 and excellent cycling stability. This study provides a facial strategy to design and construct high-performance metal oxides for energy storage.

Improvement of the electrochemical properties via poly(3,4-ethylenedioxythiophene) oriented micro/nanorods

NASA Astrophysics Data System (ADS)

Li, Yu; Wang, Bichen; Chen, Huimin; Feng, Wei

Arrays of oriented poly(3,4-ethylenedioxythiophene) (PEDOT) micro/nanorods are synthesized by electrochemical galvanostatic method at the current density of 1 mA cm -2 in the cetyltrimethylammonium bromide (CTAB) aqueous solution whose pH value is 1. The CTAB is used both as the surfactant and the supporting salt in the electrolyte solution. The electrochemical properties of PEDOT films are characterized by cyclic voltammetry and galvanostatic charge/discharge techniques, which indicate that the arrays of oriented PEDOT micro/nanorods can be applied as the electrode materials of supercapacitors. In addition, the cycling performance of PEDOT micro/nanorods is much better than that of traditional PEDOT particles. The effects of the concentration of CTAB, the current density, and pH value of electrolyte solutions on the morphologies and electrochemical properties of PEDOT films are investigated. The mechanism of different morphologies formation is discussed in this study as well.

Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor.

PubMed

Wu, Di; Lou, Zhenhua; Wang, Yuange; Xu, Tingting; Shi, Zhifeng; Xu, Junmin; Tian, Yongtao; Li, Xinjian

2017-10-27

Few-layer MoS 2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS 2 /Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS 2 /SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS 2 -based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ∼50% RH), with good repeatability and selectivity of the MoS 2 /SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS 2 /SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

Fast reconstruction of off-axis digital holograms based on digital spatial multiplexing.

PubMed

Sha, Bei; Liu, Xuan; Ge, Xiao-Lu; Guo, Cheng-Shan

2014-09-22

A method for fast reconstruction of off-axis digital holograms based on digital multiplexing algorithm is proposed. Instead of the existed angular multiplexing (AM), the new method utilizes a spatial multiplexing (SM) algorithm, in which four off-axis holograms recorded in sequence are synthesized into one SM function through multiplying each hologram with a tilted plane wave and then adding them up. In comparison with the conventional methods, the SM algorithm simplifies two-dimensional (2-D) Fourier transforms (FTs) of four N*N arrays into a 1.25-D FTs of one N*N arrays. Experimental results demonstrate that, using the SM algorithm, the computational efficiency can be improved and the reconstructed wavefronts keep the same quality as those retrieved based on the existed AM method. This algorithm may be useful in design of a fast preview system of dynamic wavefront imaging in digital holography.

Pt/Ni(OH)2–NiOOH/Pd multi-walled hollow nanorod arrays as superior electrocatalysts for formic acid electrooxidation† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5sc02544c Click here for additional data file.

PubMed Central

Xu, Han; Ding, Liang-Xin; Feng, Jin-Xian

2015-01-01

The catalytic activity and durability are crucial for the development of high-performance electrocatalysts. To design electrocatalysts with excellent electroactivity and durability, the structure and composition are two important guiding principles. In this work, novel Pt/Ni(OH)2–NiOOH/Pd multi-walled hollow nanorod arrays (MHNRAs) are successfully synthesized. The unique MHNRAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Because of the special surface and synergistic effects, the Pt/Ni(OH)2–NiOOH/Pd MHNRA electrocatalysts exhibit high catalytic activity, high durability and superior CO poisoning tolerance for the electrooxidation of formic acid in comparison with Pt@Pd MHNRAs, commercial Pt/C, Pd/C and PtRu/C catalysts. PMID:28757980

GPU-Powered Coherent Beamforming

NASA Astrophysics Data System (ADS)

Magro, A.; Adami, K. Zarb; Hickish, J.

2015-03-01

Graphics processing units (GPU)-based beamforming is a relatively unexplored area in radio astronomy, possibly due to the assumption that any such system will be severely limited by the PCIe bandwidth required to transfer data to the GPU. We have developed a CUDA-based GPU implementation of a coherent beamformer, specifically designed and optimized for deployment at the BEST-2 array which can generate an arbitrary number of synthesized beams for a wide range of parameters. It achieves ˜1.3 TFLOPs on an NVIDIA Tesla K20, approximately 10x faster than an optimized, multithreaded CPU implementation. This kernel has been integrated into two real-time, GPU-based time-domain software pipelines deployed at the BEST-2 array in Medicina: a standalone beamforming pipeline and a transient detection pipeline. We present performance benchmarks for the beamforming kernel as well as the transient detection pipeline with beamforming capabilities as well as results of test observation.

Strongly hydrogen-bond acidic polymer and methods of making and using

DOEpatents

Grate, Jay W.; Kaganove, Steven N.

2000-01-01

The present invention is a sorbent polymer with the (AB)n sequence where the fluorinated interactive A segment is fluoroalkyl-substituted bisphenol and the oligosiloxane B segment is an oligodimethylsiloxane. More specifically, the fluoroalkyl-substituted bisphenol contains two allyl groups and the oligodimethylsiloxane has terminal Si--H groups. The sorbent polymer may be used as thin films on a variety of chemical sensors, or as a component of a thin film on a chemical sensor. Crosslinked sorbent polymers are processable into stable thin films on sensor devices. Sorbent polymers are also useful in sensor arrays, in surface acoustic wave sensors, and in cladding of optical fibers. Sensor arrays provide better selectivity than single sensors and permit identification and quantification of more than one species in a mixture. The sorbent polymer is synthesized by hydrosilylation polymerization which is achieved by catalyzed heating.

Quantifying highly efficient incoherent energy transfer in perylene-based multichromophore arrays.

PubMed

Webb, James E A; Chen, Kai; Prasad, Shyamal K K; Wojciechowski, Jonathan P; Falber, Alexander; Thordarson, Pall; Hodgkiss, Justin M

2016-01-21

Multichromophore perylene arrays were designed and synthesized to have extremely efficient resonance energy transfer. Using broadband ultrafast photoluminescence and transient absorption spectroscopies, transfer timescales of approximately 1 picosecond were resolved, corresponding to efficiencies of up to 99.98%. The broadband measurements also revealed spectra corresponding to incoherent transfer between localized states. Polarization resolved spectroscopy was used to measure the dipolar angles between donor and acceptor chromophores, thereby enabling geometric factors to be fixed when assessing the validity of Förster theory in this regime. Förster theory was found to predict the correct magnitude of transfer rates, with measured ∼2-fold deviations consistent with the breakdown of the point-dipole approximation at close approach. The materials presented, along with the novel methods for quantifying ultrahigh energy transfer efficiencies, will be valuable for applications demanding extremely efficient energy transfer, including fluorescent solar concentrators, optical gain, and photonic logic devices.

Annealing effect on the photoluminescence properties of ZnO nanorod array prepared by a PLD-assistant wet chemical method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei Sufeng; Lian Jianshe; Wu Hua, E-mail: weisufeng@gmail.com

2010-11-15

Well-aligned ZnO nanorod arrays were synthesized by a wet chemical method on the glass substrate with ZnO thin film as seed layer prepared by pulsed laser deposition. The effect of annealing temperature on the luminescence characteristics was investigated. As the annealing temperature increased, the photoluminescence properties show a general enhancing tendency. The nanorod array with high ultraviolet emission and negligible visible light emission (designated by the photoluminescence intensity ratio of ultraviolet to visible emission of 66.4) is obtained by annealing the sample at 700 deg. C for 1 h. Based on the results of X-ray photoelectron spectroscopy and photoluminescence spectra,more » the mechanisms of visible emission were discussed. - Research Highlights: {yields} ZnO nanorod array with good crystallography, low defects concentration and good optical property was obtained after annealed at 700 deg. C for 1 h. {yields} The transition from the conduction band to the O{sub i} level may be responsible for the yellow-green emission. {yields} The yellow emission may originate from the presence of Zn(OH){sub 2} on the surface or the band transition from conduction band to V{sub o}Zn{sub i} level. {yields} The transition from the Zn{sub i} level to the level should produce an orange emission or an orange-red emission.« less

Two-dimensional systolic-array architecture for pixel-level vision tasks

NASA Astrophysics Data System (ADS)

Vijverberg, Julien A.; de With, Peter H. N.

2010-05-01

This paper presents ongoing work on the design of a two-dimensional (2D) systolic array for image processing. This component is designed to operate on a multi-processor system-on-chip. In contrast with other 2D systolic-array architectures and many other hardware accelerators, we investigate the applicability of executing multiple tasks in a time-interleaved fashion on the Systolic Array (SA). This leads to a lower external memory bandwidth and better load balancing of the tasks on the different processing tiles. To enable the interleaving of tasks, we add a shadow-state register for fast task switching. To reduce the number of accesses to the external memory, we propose to share the communication assist between consecutive tasks. A preliminary, non-functional version of the SA has been synthesized for an XV4S25 FPGA device and yields a maximum clock frequency of 150 MHz requiring 1,447 slices and 5 memory blocks. Mapping tasks from video content-analysis applications from literature on the SA yields reductions in the execution time of 1-2 orders of magnitude compared to the software implementation. We conclude that the choice for an SA architecture is useful, but a scaled version of the SA featuring less logic with fewer processing and pipeline stages yielding a lower clock frequency, would be sufficient for a video analysis system-on-chip.

Discrimination of saturated alkanes and relevant volatile compounds via the utilization of a conceptual fluorescent sensor array based on organoboron-containing polymers.

PubMed

Qi, Yanyu; Xu, Wenjun; Kang, Rui; Ding, Nannan; Wang, Yelei; He, Gang; Fang, Yu

2018-02-21

This work reports a conceptual sensor array for the highly discriminative analysis of 20 clinically and environmentally relevant volatile small organic molecules (VSOMs), including saturated alkanes and common solvents, in the air at room temperature. For the construction of the sensor array, a four coordinated, non-planar mono-boron complex and four relevant polymers are synthesized. Based on the polymers and the use of different substrates, 8 fluorescent films have been fabricated. Integration of the film-based sensors results in the sensor array, which demonstrates unprecedented discriminating capability toward the VSOMs. Moreover, for the signal molecule of lung cancer, n -pentane, the response time is less than 1 s, the experimental detection limit is lower than 3.7 ppm, and after repeating the tests over 50 times no observable degradation was observed. The superior sensing performance is partially ascribed to the tetrahedral structure of the boron centers in the polymers as it may produce molecular channels in the films, which are a necessity for fast and reversible sensing. In addition, the polarity of the micro-channels may endow the films with additional selectivity towards the analytes. The design as demonstrated provides an effective strategy to improve the sensing performance of fluorescent films to very challenging analytes, such as saturated alkanes.

Unique Three-Dimensional InP Nanopore Arrays for Improved Photoelectrochemical Hydrogen Production.

PubMed

Li, Qiang; Zheng, Maojun; Ma, Liguo; Zhong, Miao; Zhu, Changqing; Zhang, Bin; Wang, Faze; Song, Jingnan; Ma, Li; Shen, Wenzhong

2016-08-31

Ordered three-dimensional (3D) nanostructure arrays hold promise for high-performance energy harvesting and storage devices. Here, we report the fabrication of InP nanopore arrays (NPs) in unique 3D architectures with excellent light trapping characteristic and large surface areas for use as highly active photoelectrodes in photoelectrochemical (PEC) hydrogen evolution devices. The ordered 3D NPs were scalably synthesized by a facile two-step etching process of (1) anodic etching of InP in neutral 3 M NaCl electrolytes to realize nanoporous structures and (2) wet chemical etching in HCl/H3PO4 (volume ratio of 1:3) solutions for removing the remaining top irregular layer. Importantly, we demonstrated that the use of neutral electrolyte of NaCl instead of other solutions, such as HCl, in anodic etching of InP can significantly passivate the surface states of 3D NPs. As a result, the maximum photoconversion efficiency obtained with ∼15.7 μm thick 3D NPs was 0.95%, which was 7.3 and 1.4 times higher than that of planar and 2D NPs. Electrochemical impedance spectroscopy and photoluminescence analyses further clarified that the improved PEC performance was attributed to the enhanced charge transfer across 3D NPs/electrolyte interfaces, the improved charge separation at 3D NPs/electrolyte junction, and the increased PEC active surface areas with our unique 3D NP arrays.

A high-power synthesized ultrawideband radiation source

NASA Astrophysics Data System (ADS)

Efremov, A. M.; Koshelev, V. I.; Plisko, V. V.; Sevostyanov, E. A.

2017-09-01

A high-power ultrawideband radiation source has been developed which is capable of synthesizing electromagnetic pulses with different frequency bands in free space. To this end, a new circuit design comprising a four-channel former of bipolar pulses of durations 2 and 3 ns has been elaborated and conditions for the stable operation of gas gaps of independent channels without external control pulses have been determined. Each element of the 2 × 2 array of combined antennas is driven from an individual channel of the pulse former. Antennas excited by pulses of the same duration are arranged diagonally. Two radiation synthesis modes have been examined: one aimed to attain ultimate field strength and the other aimed to attain an ultimate width of the radiation spectrum. The modes were changed by changing the time delay between the 2-ns and 3-ns pulses. For the first mode, radiation pulses with a frequency band of 0.2-0.8 GHz and an effective potential of 500 kV have been obtained. The synthesized radiation pulses produced in the second mode had an extended frequency band (0.1-1 GHz) and an effective potential of 220 kV. The pulse repetition frequency was 100 Hz.

Group tele-immersion:enabling natural interactions between groups at distant sites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Christine L.; Stewart, Corbin; Nashel, Andrew

2005-08-01

We present techniques and a system for synthesizing views for video teleconferencing between small groups. In place of replicating one-to-one systems for each pair of users, we create a single unified display of the remote group. Instead of performing dense 3D scene computation, we use more cameras and trade-off storage and hardware for computation. While it is expensive to directly capture a scene from all possible viewpoints, we have observed that the participants viewpoints usually remain at a constant height (eye level) during video teleconferencing. Therefore, we can restrict the possible viewpoint to be within a virtual plane without sacrificingmore » much of the realism, and in cloning so we significantly reduce the number of required cameras. Based on this observation, we have developed a technique that uses light-field style rendering to guarantee the quality of the synthesized views, using a linear array of cameras with a life-sized, projected display. Our full-duplex prototype system between Sandia National Laboratories, California and the University of North Carolina at Chapel Hill has been able to synthesize photo-realistic views at interactive rates, and has been used to video conference during regular meetings between the sites.« less

Wide Tuning Capability for Spacecraft Transponders

NASA Technical Reports Server (NTRS)

Lux, James; Mysoor, Narayan; Shah, Biren; Cook, Brian; Smith, Scott

2007-01-01

A document presents additional information on the means of implementing a capability for wide tuning of microwave receiver and transmitter frequencies in the development reported in the immediately preceding article, VCO PLL Frequency Synthesizers for Spacecraft Transponders (NPO- 42909). The reference frequency for a PLL-based frequency synthesizer is derived from a numerically controlled oscillator (NCO) implemented in digital logic, such that almost any reference frequency can be derived from a fixed crystal reference oscillator with microhertz precision. The frequency of the NCO is adjusted to track the received signal, then used to create another NCO frequency used to synthesize the transmitted signal coherent with, and at a specified frequency ratio to, the received signal. The frequencies can be changed, even during operation, through suitable digital programming. The NCOs and the related tracking loops and coherent turnaround logic are implemented in a field-programmable gate array (FPGA). The interface between the analog microwave receiver and transmitter circuits and the FPGA includes analog-to-digital and digital-toanalog converters, the sampling rates of which are chosen to minimize spurious signals and otherwise optimize performance. Several mixers and filters are used to properly route various signals.

Surface analysis and mechanical behaviour mapping of vertically aligned CNT forest array through nanoindentation

NASA Astrophysics Data System (ADS)

Koumoulos, Elias P.; Charitidis, C. A.

2017-02-01

Carbon nanotube (CNT) based architectures have increased the scientific interest owning to their exceptional performance rendering them promising candidates for advanced industrial applications in the nanotechnology field. Despite individual CNTs being considered as one of the most known strong materials, much less is known about other CNT forms, such as CNT arrays, in terms of their mechanical performance (integrity). In this work, thermal chemical vapor deposition (CVD) method is employed to produce vertically aligned multiwall (VA-MW) CNT carpets. Their structural properties were studied by means of scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Raman spectroscopy, while their hydrophobic behavior was investigated via contact angle measurements. The resistance to indentation deformation of VA-MWCNT carpets was investigated through nanoindentation technique. The synthesized VA-MWCNTs carpets consisted of well-aligned MWCNTs. Static contact angle measurements were performed with water and glycerol, revealing a rather super-hydrophobic behavior. The structural analysis, hydrophobic behavior and indentation response of VA-MWCNTs carpets synthesized via CVD method are clearly demonstrated. Additionally, cycle indentation load-depth curve was applied and hysteresis loops were observed in the indenter loading-unloading cycle due to the local stress distribution. Hardness (as resistance to applied load) and modulus mapping, at 200 nm of displacement for a grid of 70 μm2 is presented. Through trajection, the resistance is clearly divided in 2 regions, namely the MWCNT probing and the in-between area MWCNT - MWCNT interface.

Analysis of residual products in benzyl chloride used for the industrial synthesis of quaternary compounds by liquid chromatography with diode-array detection.

PubMed

Prieto-Blanco, M C; López-Mahía, P; Prada-Rodríguez, D

2009-02-01

In industrial and pharmaceutical processes, the study of residual products becomes essential to guarantee the quality of compounds and to eliminate or minimize toxic residual products. Knowledge about the origin of impurities (raw materials, processes, the contamination of industrial plants, etc.) is necessary in preventive treatment and in the control of a product's lifecycle. Benzyl chloride is used as raw material to synthesize several quaternary ammonium compounds, such as benzalkonium chloride, which may have pharmaceutical applications. Benzaldehyde, benzyl alcohol, toluene, chloro derivatives of toluene, and dibenzyl ether are compounds that may be found as impurities in technical benzyl chloride. We proposed a high-performance liquid chromatography method for the separation of these compounds, testing two stationary phases with different dimensions and particle sizes, with the application of photodiode array-detection. The linearity for four possible impurities (benzaldehyde, toluene, alpha,alpha-dichlorotoluene, and 2-chlorotoluene) ranged from 0.1 to 10 microg/mL, limits of detection from 11 to 34 ng/mL, and repeatability from 1% to 2.9% for a 0.3-1.2 microg/mL concentration range. The method was applied to samples of technical benzyl chloride, and alpha,alpha-dichlorotoluene and benzaldehyde were identified by spectral analysis and quantitated. The selection of benzyl chloride with lower levels of impurities is important to guarantee the reduction of residual products in further syntheses.

Charge Transport in Semiconductor Nanocrystal Solids

NASA Astrophysics Data System (ADS)

Talapin, Dmitri; Shevchenko, Elena; Lee, Jong Soo; Urban, Jeffrey; Mitzi, David; Murray, Christopher

2007-03-01

Self-assembly of chemically-synthesized nanocrystals can yield complex long-range ordered structures which can be used as model systems for studying transport phenomena in low-dimensional materials [1]. Treatment of close-packed PbSe nanocrystal arrays with hydrazine enhanced exchange coupling between the nanocrystals and improved conductance by more than ten orders of magnitude compared to native nanocrystal films [2]. The conductivity of PbSe nanocrystal solids can be switched between n- and p-type transports by controlling the saturation of electronic states at nanocrystal surfaces. Nanocrystal arrays form the n- and p-channels of field-effect transistors with electron and hole mobilities of 2.5 cm^2V-1s-1 and 0.3 cm^2V-1s-1, respectively, and current modulation Ion/Ioff˜10^3-10^4. The field-effect mobility in PbSe nanocrystal arrays is higher than the mobility of organic transistors while the easy switch between n- and p-transport allows realization of complimentary circuits and p-n junctions for nanocrystal-based solar cells and thermoelectric devices. [1] E. V. Shevchenko, D. V. Talapin, N. A. Kotov, S. O'Brien, C. B. Murray. Nature 439, 55 (2006). [2] D. V. Talapin, C. B. Murray. Science 310, 86 (2005).

Sodium fluoride-assisted modulation of anodized TiO₂ nanotube for dye-sensitized solar cells application.

PubMed

Yun, Jung-Ho; Ng, Yun Hau; Ye, Changhui; Mozer, Attila J; Wallace, Gordon G; Amal, Rose

2011-05-01

This work reports the use of sodium fluoride (in ethylene glycol electrolyte) as the replacement of hydrofluoric acid and ammonium fluoride to fabricate long and perpendicularly well-aligned TiO₂ nanotube (TNT) (up to 21 μm) using anodization. Anodizing duration, applied voltage and electrolyte composition influenced the geometry and surface morphologies of TNT. The growth mechanism of TNT is interpreted by analyzing the current transient profile and the total charge density generated during anodization. The system with low water content (2 wt %) yielded a membrane-like mesoporous TiO₂ film, whereas high anodizing voltage (70 V) resulted in the unstable film of TNT arrays. An optimized condition using 5 wt % water content and 60 V of anodizing voltage gave a stable array of nanotube with controllable length and pore diameter. Upon photoexcitation, TNTs synthesized under this condition exhibited a slower charge recombination rate as nanotube length increased. When made into cis-diisothiocyanato-bis(2,2̀-bipyridyl-4,4̀-dicarboxylato) ruthenium(II) bis (tetrabutyl-ammonium)(N719) dye-sensitized solar cells, good device efficiency at 3.33 % based on the optimized TNT arrays was achieved with longer electron time compared with most mesoporous TiO₂ films.

Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection.

PubMed

Cui, Jiewu; Adeloju, Samuel B; Wu, Yucheng

2014-01-27

A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO(x)) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA-BSA-GLA-GO(x) nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm(-2) mM(-1) for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5-6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Hierarchical Oriented Anatase TiO2 Nanostructure arrays on Flexible Substrate for Efficient Dye-sensitized Solar Cells

PubMed Central

Wu, Wu-Qiang; Rao, Hua-Shang; Xu, Yang-Fan; Wang, Yu-Fen; Su, Cheng-Yong; Kuang, Dai-Bin

2013-01-01

The vertically oriented anatase single crystalline TiO2 nanostructure arrays (TNAs) consisting of TiO2 truncated octahedrons with exposed {001} facets or hierarchical TiO2 nanotubes (HNTs) consisting of numerous nanocrystals on Ti-foil substrate were synthesized via a two-step hydrothermal growth process. The first step hydrothermal reaction of Ti foil and NaOH leads to the formation of H-titanate nanowire arrays, which is further performed the second step hydrothermal reaction to obtain the oriented anatase single crystalline TiO2 nanostructures such as TiO2 nanoarrays assembly with truncated octahedral TiO2 nanocrystals in the presence of NH4F aqueous or hierarchical TiO2 nanotubes with walls made of nanocrystals in the presence of pure water. Subsequently, these TiO2 nanostructures were utilized to produce dye-sensitized solar cells in a backside illumination pattern, yielding a significant high power conversion efficiency (PCE) of 4.66% (TNAs, JSC = 7.46 mA cm−2, VOC = 839 mV, FF = 0.75) and 5.84% (HNTs, JSC = 10.02 mA cm−2, VOC = 817 mV, FF = 0.72), respectively. PMID:23715529

A software controllable modular RF signal generator with multichannel transmission capabilities.

PubMed

Shaw, Z; Feilner, W; Esser, B; Dickens, J C; Neuber, A A

2017-09-01

A software controllable system which generates and transmits user defined RF signals is discussed. The system is implemented with multiple, modular transmitting channels that allow the user to easily replace parts such as amplifiers or antennas. Each channel is comprised of a data pattern generator (DPG), a digital to analog converter (DAC), a power amplifier, and a transmitting antenna. All channels are controlled through a host PC and synchronized through a master clock signal provided to each DAC by an external clock source. Signals to be transmitted are generated through the DPG control software on the PC or can be created by the user in a numerical computing environment. Three experiments are discussed using a two- and four-channel antenna array incorporating Chebyshev tapered TEM horn antennas. Transmitting distinct sets of nonperiodic bipolar impulses through each of the antennas in the array enabled synthesizing a sinusoidal signal of specific frequency in free space. Opposite to the standard phased array approach, each antenna radiates a distinctly different signal rather than the same signal simply phase shifted. The presented approach may be employed as a physical layer of encryption dependent on the position of the receiving antenna.

CMOS detector arrays in a virtual 10-kilopixel camera for coherent terahertz real-time imaging.

PubMed

Boppel, Sebastian; Lisauskas, Alvydas; Max, Alexander; Krozer, Viktor; Roskos, Hartmut G

2012-02-15

We demonstrate the principle applicability of antenna-coupled complementary metal oxide semiconductor (CMOS) field-effect transistor arrays as cameras for real-time coherent imaging at 591.4 GHz. By scanning a few detectors across the image plane, we synthesize a focal-plane array of 100×100 pixels with an active area of 20×20 mm2, which is applied to imaging in transmission and reflection geometries. Individual detector pixels exhibit a voltage conversion loss of 24 dB and a noise figure of 41 dB for 16 μW of the local oscillator (LO) drive. For object illumination, we use a radio-frequency (RF) source with 432 μW at 590 GHz. Coherent detection is realized by quasioptical superposition of the image and the LO beam with 247 μW. At an effective frame rate of 17 Hz, we achieve a maximum dynamic range of 30 dB in the center of the image and more than 20 dB within a disk of 18 mm diameter. The system has been used for surface reconstruction resolving a height difference in the μm range.

High optical switching speed and flexible electrochromic display based on WO3 nanoparticles with ZnO nanorod arrays' supported electrode

NASA Astrophysics Data System (ADS)

Wang, Mingjun; Fang, Guojia; Yuan, Longyan; Huang, Huihui; Sun, Zhenhua; Liu, Nishuang; Xia, Shanhong; Zhao, Xingzhong

2009-05-01

The electrochromic (EC) property of WO3 nanoparticles grown on vertically self-aligned ZnO nanorods (ZNRs) is reported. An electrochromic character display based on WO3 nanoparticle-modified ZnO nanorod arrays on a flexible substrate has been fabricated and demonstrated. The ZNRs were first synthesized on ZnO-seed-coated In2O3:Sn (ITO) glass (1 cm2 cell) and polyethylene terephthalate (PET) (4 cm2 cell) substrates by a low temperature hydrothermal method, and then amorphous WO3 nanoparticles were grown directly on the surface of the ZNRs by the pulsed laser deposition (PLD) method. The ZNR-based EC device shows high transparence, good electrochromic stability and fast switching speed (4.2 and 4 s for coloration and bleaching, respectively, for a 1 cm2 cell). The good performance of the ZNR electrode-based EC display can be attributed to the large surface area, high crystallinity and good electron transport properties of the ZNR arrays. Its high contrast, fast switching, good memory and flexible characteristics indicate it is a promising candidate for flexible electrochromic displays or electronic paper.

Fabrication of CoFe2O4 ferrite nanowire arrays in porous silicon template and their local magnetic properties

NASA Astrophysics Data System (ADS)

Hui, Zheng; Man-Gui, Han; Long-Jiang, Deng

2016-02-01

CoFe2O4 ferrite nanowire arrays are fabricated in porous silicon templates. The porous silicon templates are prepared via metal-assisted chemical etching with gold (Au) nanoparticles as the catalyst. Subsequently, CoFe2O4 ferrite nanowires are successfully synthesized into porous silicon templates by the sol-gel method. The magnetic hysteresis loop of nanowire array shows an isotropic feature of magnetic properties. The coercivity and squareness ratio (Mr/Ms) of ensemble nanowires are found to be 630 Oe (1 Oe, = 79.5775 A·m-1 and 0.4 respectively. However, the first-order reversal curve (FORC) is adopted to reveal the probability density function of local magnetostatic properties (i.e., interwire interaction field and coercivity). The FORC diagram shows an obvious distribution feature for interaction field and coercivity. The local coercivity with a value of about 1000 Oe is found to have the highest probability. Project supported by the National Natural Science Foundation of China (Grant No. 61271039), the Scientific Projects of Sichuan Province, China (Grant No. 2015HH0016), and the Natural Science Foundations of Zhejiang Province, China (Grant Nos. LQ12E02001 and Y107255).

One-step hydrothermal synthesis of feather duster-like NiS@MoS2 with hierarchical array structure for the Pt-free dye-sensitized solar cell

NASA Astrophysics Data System (ADS)

Su, Lijun; Xiao, Yaoming; Han, Gaoyi; Lin, Jeng-Yu

2018-04-01

Novel feather duster-like nickel sulfide (NiS) @ molybdenum sulfide (MoS2) with hierarchical array structure is synthesized via a simple one-step hydrothermal method, in which a major structure of rod-like NiS in the center and a secondary structure of MoS2 nanosheets with a thickness of about 15-55 nm on the surface. The feather duster-like NiS@MoS2 is employed as the counter electrode (CE) material for the dye-sensitized solar cell (DSSC), which exhibits superior electrocatalytic activity due to its feather duster-like hierarchical array structure can not only support the fast electron transfer and electrolyte diffusion channels, but also can provide high specific surface area (238.19 m2 g-1) with abundant active catalytic sites and large electron injection efficiency from CE to electrolyte. The DSSC based on the NiS@MoS2 CE achieves a competitive photoelectric conversion efficiency of 8.58%, which is higher than that of the NiS (7.13%), MoS2 (7.33%), and Pt (8.16%) CEs under the same conditions. [Figure not available: see fulltext.

Morphology, stability, and X-ray absorption spectroscopic study of iron oxide (Hematite) nanoparticles prepared by micelle nanolithography

NASA Astrophysics Data System (ADS)

Bera, Anupam; Bhattacharya, Atanu; Tiwari, N.; Jha, S. N.; Bhattacharyya, D.

2018-03-01

Currently, considerable effort is being made towards synthesis and characterization of iron oxide nanoparticles. In this article, we report on the preparation and characterization of iron oxide nanoparticle (NP) arrays supported on natively oxidized Si(100) surface. The NPs are synthesized by reverse micelle nanolithography technique and are then deposited onto natively oxidized Si(100) surface via spin-coating. Plasma oxidation followed by high temperature annealing results in a unimodal size distribution of pseudohexagonally-ordered array of iron oxide NPs (with ∼14 nm mean diameter and ∼5 nm mean height). High temperature annealing does not fragment the NPs. Particles are sinter-resistant: the unimodal arrays are robust with respect to thermal treatment. X-ray absorption spectroscopy (XAS), including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS), reveals that structure of the iron oxide particle resembles closely the hematite α-Fe2O3 structure. Furthermore, with the help of EXAFS spectra, we eliminate the possibility of γ-Fe2O3, Fe3O4, FeO and FeO(OH) structures for the NPs.

High Discharge Energy Density at Low Electric Field Using an Aligned Titanium Dioxide/Lead Zirconate Titanate Nanowire Array.

PubMed

Zhang, Dou; Liu, Weiwei; Guo, Ru; Zhou, Kechao; Luo, Hang

2018-02-01

Polymer-based capacitors with high energy density have attracted significant attention in recent years due to their wide range of potential applications in electronic devices. However, the obtained high energy density is predominantly dependent on high applied electric field, e.g., 400-600 kV mm -1 , which may bring more challenges relating to the failure probability. Here, a simple two-step method for synthesizing titanium dioxide/lead zirconate titanate nanowire arrays is exploited and a demonstration of their ability to achieve high discharge energy density capacitors for low operating voltage applications is provided. A high discharge energy density of 6.9 J cm -3 is achieved at low electric fields, i.e., 143 kV mm -1 , which is attributed to the high relative permittivity of 218.9 at 1 kHz and high polarization of 23.35 µC cm -2 at this electric field. The discharge energy density obtained in this work is the highest known for a ceramic/polymer nanocomposite at such a low electric field. The novel nanowire arrays used in this work are applicable to a wide range of fields, such as energy harvesting, energy storage, and photocatalysis.

Large-scale fabrication of polymer/Ag core-shell nanorod array as flexible SERS substrate by combining direct nanoimprint and electroless deposition

NASA Astrophysics Data System (ADS)

Liu, Sisi; Xu, Zhimou; Sun, Tangyou; Zhao, Wenning; Wu, Xinghui; Ma, Zhichao; Xu, Haifeng; He, Jian; Chen, Cunhua

2014-06-01

We demonstrate a highly sensitive surface-enhanced Raman scattering (SERS) substrate, which consists of Ag nanoparticles (NPs) assembled on the surface of a nanopatterned polymer film. The fabrication route of a polymer/Ag core-shell nanorod (PACSN) array employed a direct nanoimprint technique to create a high-resolution polymer nanorod array. The obtained nanopatterned polymer film was subjected to electroless deposition to form a sea-cucumber-like Ag shell over the surface of the polymer nanorod. The morphology and structures of PACSNs were analyzed by using scanning electron microscopy and X-ray diffraction. The as-synthesized PACSNs exhibited a remarkable SERS activity and Raman signal reproducibility to rhodamine 6G, and a concentration down to 10-12 M can be identified. The effect of electroless deposition time of Ag NPs onto the polymer nanorod surface was investigated. It was found that the electroless deposition time played an important role in SERS activity. Our results revealed that the combination of direct nanoimprint and electroless deposition provided a convenient and cost-effective way for large-scale fabrication of reliable SERS substrates without the requirement of expensive instruments.

Nanomanufacturing of silicon surface with a single atomic layer precision via mechanochemical reactions.

PubMed

Chen, Lei; Wen, Jialin; Zhang, Peng; Yu, Bingjun; Chen, Cheng; Ma, Tianbao; Lu, Xinchun; Kim, Seong H; Qian, Linmao

2018-04-18

Topographic nanomanufacturing with a depth precision down to atomic dimension is of importance for advancement of nanoelectronics with new functionalities. Here we demonstrate a mask-less and chemical-free nanolithography process for regio-specific removal of atomic layers on a single crystalline silicon surface via shear-induced mechanochemical reactions. Since chemical reactions involve only the topmost atomic layer exposed at the interface, the removal of a single atomic layer is possible and the crystalline lattice beneath the processed area remains intact without subsurface structural damages. Molecular dynamics simulations depict the atom-by-atom removal process, where the first atomic layer is removed preferentially through the formation and dissociation of interfacial bridge bonds. Based on the parametric thresholds needed for single atomic layer removal, the critical energy barrier for water-assisted mechanochemical dissociation of Si-Si bonds was determined. The mechanochemical nanolithography method demonstrated here could be extended to nanofabrication of other crystalline materials.

Printing-assisted surface modifications of patterned ultrafiltration membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wardrip, Nathaniel C.; Dsouza, Melissa; Urgun-Demirtas, Meltem

Understanding and restricting microbial surface attachment will enhance wastewater treatment with membranes. We report a maskless lithographic patterning technique for the generation of patterned polymer coatings on ultrafiltration membranes. Polyethylene glycol, zwitterionic, or negatively charged hydrophilic polymer compositions in parallel- or perpendicular-striped patterns with respect to feed flow were evaluated using wastewater. Membrane fouling was dependent on the orientation and chemical composition of the coatings. Modifications reduced alpha diversity in the attached microbial community (Shannon indices decreased from 2.63 to 1.89) which nevertheless increased with filtration time. Sphingomonas species, which condition membrane surfaces and facilitate cellular adhesion, were depleted inmore » all modified membranes. Microbial community structure was significantly different between control, different patterns, and different chemistries. Lastly, this study broadens the tools for surface modification of membranes with polymer coatings and for understanding and optimization of antifouling surfaces.« less

Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM

PubMed Central

Bittencourt, Carla; Bals, Sara; Van Tendeloo, Gustaaf

2013-01-01

Summary Focused-electron-beam-induced deposition (FEBID) is used as a direct-write approach to decorate ultrasmall Pt nanoclusters on carbon nanotubes at selected sites in a straightforward maskless manner. The as-deposited nanostructures are studied by transmission electron microscopy (TEM) in 2D and 3D, demonstrating that the Pt nanoclusters are well-dispersed, covering the selected areas of the CNT surface completely. The ability of FEBID to graft nanoclusters on multiple sides, through an electron-transparent target within one step, is unique as a physical deposition method. Using high-resolution TEM we have shown that the CNT structure can be well preserved thanks to the low dose used in FEBID. By tuning the electron-beam parameters, the density and distribution of the nanoclusters can be controlled. The purity of as-deposited nanoclusters can be improved by low-energy electron irradiation at room temperature. PMID:23399584

Printing-assisted surface modifications of patterned ultrafiltration membranes

DOE PAGES

Wardrip, Nathaniel C.; Dsouza, Melissa; Urgun-Demirtas, Meltem; ...

2016-10-17

Understanding and restricting microbial surface attachment will enhance wastewater treatment with membranes. We report a maskless lithographic patterning technique for the generation of patterned polymer coatings on ultrafiltration membranes. Polyethylene glycol, zwitterionic, or negatively charged hydrophilic polymer compositions in parallel- or perpendicular-striped patterns with respect to feed flow were evaluated using wastewater. Membrane fouling was dependent on the orientation and chemical composition of the coatings. Modifications reduced alpha diversity in the attached microbial community (Shannon indices decreased from 2.63 to 1.89) which nevertheless increased with filtration time. Sphingomonas species, which condition membrane surfaces and facilitate cellular adhesion, were depleted inmore » all modified membranes. Microbial community structure was significantly different between control, different patterns, and different chemistries. Lastly, this study broadens the tools for surface modification of membranes with polymer coatings and for understanding and optimization of antifouling surfaces.« less

Micro sculpting technology using DPSSL

NASA Astrophysics Data System (ADS)

Chang, Won-Seok; Shin, Bosung; Kim, Jae-gu; Whang, Kyung-Hyun

2003-11-01

Multiple pulse laser ablation of polymer is performed with DPSS (Diode Pumped Solid State) 3rd harmonic Nd:YVO4 laser (355 nm) in order to fabricate three-dimensional micro components. Here we considered mechanistic aspects of the interaction between UV laser and polymer to obtain optimum process conditions for maskless photomachining using DPSSL. The photo-physical and photochemical parameters such as laser wavelength and optical characteristics of polymers are investigated by experiments to reduce plume effect, which induce the re-deposited debris on the surface of substrate. In this study, LDST (laser direct sculpting technique) are developed to gain various three-dimensional shape with size less than 500 micrometer. Main process sequences are from rapid prototyping technology such as CAD/CAM modeling of products, machining path generation, layer-by-layer machining, and so on. This method can be applied to manufacture the prototype of micro device and the polymer mould for mass production without expensive mask fabrication.

Development of a 3D printer using scanning projection stereolithography

PubMed Central

Lee, Michael P.; Cooper, Geoffrey J. T.; Hinkley, Trevor; Gibson, Graham M.; Padgett, Miles J.; Cronin, Leroy

2015-01-01

We have developed a system for the rapid fabrication of low cost 3D devices and systems in the laboratory with micro-scale features yet cm-scale objects. Our system is inspired by maskless lithography, where a digital micromirror device (DMD) is used to project patterns with resolution up to 10 µm onto a layer of photoresist. Large area objects can be fabricated by stitching projected images over a 5cm2 area. The addition of a z-stage allows multiple layers to be stacked to create 3D objects, removing the need for any developing or etching steps but at the same time leading to true 3D devices which are robust, configurable and scalable. We demonstrate the applications of the system by printing a range of micro-scale objects as well as a fully functioning microfluidic droplet device and test its integrity by pumping dye through the channels. PMID:25906401

Ink jet assisted metallization for low cost flat plate solar cells

NASA Technical Reports Server (NTRS)

Teng, K. F.; Vest, R. W.

1987-01-01

Computer-controlled ink-jet-assisted metallization of the front surface of solar cells with metalorganic silver inks offers a maskless alternative method to conventional photolithography and screen printing. This method can provide low cost, fine resolution, reduced process complexity, avoidance of degradation of the p-n junction by firing at lower temperature, and uniform line film on rough surface of solar cells. The metallization process involves belt furnace firing and thermal spiking. With multilayer ink jet printing and firing, solar cells of about 5-6 percent efficiency without antireflection (AR) coating can be produced. With a titanium thin-film underlayer as an adhesion promoter, solar cells of average efficiency 8.08 percent without AR coating can be obtained. This efficiency value is approximately equal to that of thin-film solar cells of the same lot. Problems with regard to lower inorganic content of the inks and contact resistance are noted.

Low-Cost Rapid Prototyping of Liquid Crystal Polymer Based Magnetic Microactuators for Glaucoma Drainage Devices

PubMed Central

Park, Hyunsu; John, Simon; Lee, Hyowon

2017-01-01

Glaucoma is one of the leading causes of blindness in the world. Although there is no cure for glaucoma, pharmaceutical or surgical interventions are known to delay the progression of this debilitating disease. In recent years, implantation of glaucoma drainage devices (GDD) have increased due to their ability to manage IOP better than other therapeutic approaches. However, only 50% of the implanted devices remain functional after 5 years often due to biofouling. Here, we report our latest progress towards developing self-clearing GDDs using integrated magnetic microactuators. Our hypothesis is that these magnetic microdevices can provide local mechanical perturbations to prophylactically remove biological accumulation. To reduce the cost and increase the throughput of fabrication, we utilize a maskless photolithography setup and commercially available liquid crystal polymer foils to create prototype devices. The mechanical response of the devices is reported and compared with the theoretical values. PMID:28269212

Low-cost rapid prototyping of liquid crystal polymer based magnetic microactuators for glaucoma drainage devices.

PubMed

Hyunsu Park; John, Simon; Hyowon Lee

2016-08-01

Glaucoma is one of the leading causes of blindness in the world. Although there is no cure for glaucoma, pharmaceutical or surgical interventions are known to delay the progression of this debilitating disease. In recent years, implantation of glaucoma drainage devices (GDD) have increased due to their ability to manage IOP better than other therapeutic approaches. However, only 50% of the implanted devices remain functional after 5 years often due to biofouling. Here, we report our latest progress towards developing self-clearing GDDs using integrated magnetic microactuators. Our hypothesis is that these magnetic microdevices can provide local mechanical perturbations to prophylactically remove biological accumulation. To reduce the cost and increase the throughput of fabrication, we utilize a maskless photolithography setup and commercially available liquid crystal polymer foils to create prototype devices. The mechanical response of the devices is reported and compared with the theoretical values.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, Nelson S.; Sarobol, Pylin; Cook, Adam

There is a rising interest in developing functional electronics using additively manufactured components. Considerations in materials selection and pathways to forming hybrid circuits and devices must demonstrate useful electronic function; must enable integration; and must complement the complex shape, low cost, high volume, and high functionality of structural but generally electronically passive additively manufactured components. This article reviews several emerging technologies being used in industry and research/development to provide integration advantages of fabricating multilayer hybrid circuits or devices. First, we review a maskless, noncontact, direct write (DW) technology that excels in the deposition of metallic colloid inks for electrical interconnects.more » Second, we review a complementary technology, aerosol deposition (AD), which excels in the deposition of metallic and ceramic powder as consolidated, thick conformal coatings and is additionally patternable through masking. As a result, we show examples of hybrid circuits/devices integrated beyond 2-D planes, using combinations of DW or AD processes and conventional, established processes.« less

Solution-processed all-oxide bulk heterojunction solar cells based on CuO nanaorod array and TiO2 nanocrystals.

PubMed

Wu, Fan; Qiao, Qiquan; Bahrami, Behzad; Chen, Ke; Pathak, Rajesh; Tong, Yanhua; Li, Xiaoyi; Zhang, Tiansheng; Jian, Ronghua

2018-05-25

We present a method to synthesize CuO nanorod array/TiO 2 nanocrystals bulk heterojunction (BHJ) on fluorine-tin-oxide (FTO) glass, in which single-crystalline p-type semiconductor of the CuO nanorod array is grown on the FTO glass by hydrothermal reaction and the n-type semiconductor of the TiO 2 precursor is filled into the CuO nanorods to form well-organized nano-interpenetrating BHJ after air annealing. The interface charge transfer in CuO nanorod array/TiO 2 heterojunction is studied by Kelvin probe force microscopy (KPFM). KPFM results demonstrate that the CuO nanorod array/TiO 2 heterojunction can realize the transfer of photo-generated electrons from the CuO nanorod array to TiO 2 . In this work, a solar cell with the structure FTO/CuO nanoarray/TiO 2 /Al is successfully fabricated, which exhibits an open-circuit voltage (V oc ) of 0.20 V and short-circuit current density (J sc ) of 0.026 mA cm -2 under AM 1.5 illumination. KPFM studies indicate that the very low performance is caused by an undesirable interface charge transfer. The interfacial surface potential (SP) shows that the electron concentration in the CuO nanorod array changes considerably after illumination due to increased photo-generated electrons, but the change in the electron concentration in TiO 2 is much less than in CuO, which indicates that the injection efficiency of the photo-generated electrons from CuO to TiO 2 is not satisfactory, resulting in an undesirable J sc in the solar cell. The interface photovoltage from the KPFM measurement shows that the low V oc results from the small interfacial SP difference between CuO and TiO 2 because the low injected electron concentration cannot raise the Fermi level significantly in TiO 2 . This conclusion agrees with the measured work function results under illumination. Hence, improvement of the interfacial electron injection is primary for the CuO nanorod array/TiO 2 heterojunction solar cells.

Electrodeposition of bismuth:tellurium nanowire arrays into porous alumina templates for thermoelectric applications

NASA Astrophysics Data System (ADS)

Trahey, Lynn

Bismuth telluride is a well-known thermoelectric material for refrigeration applications. Thermoelectrics possess several advantages over conventional refrigeration and power generation devices, yet are not widely-used due to low efficiencies. It has been predicted and shown experimentally that the efficiency of thermoelectric devices increases when the semiconducting materials have reduced dimensions. Therefore, the aim of this research was to show enhanced thermoelectric efficiency in one-dimensional nanowires. The nanowires were synthesized via electrochemical deposition into porous alumina templates. Electrodeposition is a versatile technique that ensures electrical continuity in the deposited material. The nanowire templates, porous alumina, were made by the double anodization of high-purity aluminum foil in oxalic acid solutions. This technique produces parallel, hexagonally packed, and nanometer-range diameter pores that can reach high aspect ratios (greater than 2000:1). The main anodization variables (electrolyte concentration, applied potential, 2nd anodization time, and temperature) were studied systematically in order to deconvolute their effects on the resulting pores and to obtain high aspect ratio pores. The porous alumina is of great importance because the pore dimensions determine the dimensions of the electrodeposited nanowires, which influence the thermoelectric performance of the nanowire arrays. Nanowire arrays were characterized in several ways. Powder X-ray diffraction was used to assess crystallinity and preferred orientation of the nanowires, revealing that the nanowires are highly crystalline and grow with strong preferred orientation such that the material is suited for optimal thermoelectric performance. Scanning electron microscopy was used to evaluate the nanowire nucleation percentage and growth-front uniformity, both of which were enhanced by pulsed-potential electrodeposition. Compositional analysis via electron microprobe indicates that the as-grown nanowires are Te-rich or Bi-deficient, which agrees with Seebeck coefficient data showing the arrays are n-type semiconductors. In collaboration with Marlow Industries, the thermoelectric performance of the arrays was gauged. The nanowire arrays were successfully contacted with robust nickel layers as revealed by the low AC resistances of the arrays. One array was incorporated into a hybrid thermoelectric device and a DeltaT of 14.8°C was measured, indicating that the measurement and electrical contact approaches were successful despite further optimization being needed.

Solution-processed all-oxide bulk heterojunction solar cells based on CuO nanaorod array and TiO2 nanocrystals

NASA Astrophysics Data System (ADS)

Wu, Fan; Qiao, Qiquan; Bahrami, Behzad; Chen, Ke; Pathak, Rajesh; Tong, Yanhua; Li, Xiaoyi; Zhang, Tiansheng; Jian, Ronghua

2018-05-01

We present a method to synthesize CuO nanorod array/TiO2 nanocrystals bulk heterojunction (BHJ) on fluorine-tin-oxide (FTO) glass, in which single-crystalline p-type semiconductor of the CuO nanorod array is grown on the FTO glass by hydrothermal reaction and the n-type semiconductor of the TiO2 precursor is filled into the CuO nanorods to form well-organized nano-interpenetrating BHJ after air annealing. The interface charge transfer in CuO nanorod array/TiO2 heterojunction is studied by Kelvin probe force microscopy (KPFM). KPFM results demonstrate that the CuO nanorod array/TiO2 heterojunction can realize the transfer of photo-generated electrons from the CuO nanorod array to TiO2. In this work, a solar cell with the structure FTO/CuO nanoarray/TiO2/Al is successfully fabricated, which exhibits an open-circuit voltage (V oc) of 0.20 V and short-circuit current density (J sc) of 0.026 mA cm‑2 under AM 1.5 illumination. KPFM studies indicate that the very low performance is caused by an undesirable interface charge transfer. The interfacial surface potential (SP) shows that the electron concentration in the CuO nanorod array changes considerably after illumination due to increased photo-generated electrons, but the change in the electron concentration in TiO2 is much less than in CuO, which indicates that the injection efficiency of the photo-generated electrons from CuO to TiO2 is not satisfactory, resulting in an undesirable J sc in the solar cell. The interface photovoltage from the KPFM measurement shows that the low V oc results from the small interfacial SP difference between CuO and TiO2 because the low injected electron concentration cannot raise the Fermi level significantly in TiO2. This conclusion agrees with the measured work function results under illumination. Hence, improvement of the interfacial electron injection is primary for the CuO nanorod array/TiO2 heterojunction solar cells.

Rapid and efficient hydrophilicity tuning of p53/mdm2 antagonists*

PubMed Central

Srivastava, Stuti; Beck, Barbara; Wang, Wei; Czarna, Anna; Holak, Tad A.; Dömling, Alexander

2009-01-01

The protein-protein interaction of p53 and mdm2 is an important anticancer target. The interface, however, is very hydrophobic and naturally results in very hydrophobic antagonists. We used the Orru three component reaction (O-3CR) along with a rapid and efficient, recently discovered amidation reaction to dramatically improve the water solubility of our recently discovered low molecular weight p53/mdm2 antagonists. Arrays of amides were synthesized with improved hydrophilicity and retainment and/or improvement of p53/mdm2 inhibitory activity. PMID:19548636

The Urbana coherent-scatter radar: Synthesis and first results

NASA Technical Reports Server (NTRS)

Gibbs, K. P.; Bowhill, S. A.

1979-01-01

A coherent scatter radar system was synthesized and several hundred hours of echo power and line of sight velocity data obtained. The coherent scatter radar utilizes a diode array and components from meteor radar. The receiving system permits a time resolution of one minute in the data. Echo power from the D region shows a high degree of variability from day to day. Examples of changes in power level at shorter time scales are observed. Velocity data show the existence of gravity waves and occasionally exhibit vertical standing wave characteristics.

Nano magnetic solid phase extraction for preconcentration of lead ions in environmental samples by a newly synthesized reagent.

PubMed

Golshekan, Mostafa; Shariati, Shahab

2013-01-01

In this study, magnetite nanoparticles with particle size lower than 47 nm were synthesized and were applied for preconcentration of Pb2+ ions from aqueous solutions. To preconcentrate the Pb2+ ions, the surface of the synthesized nano particles was modified with sodium dodecyl sulfate (SDS) as an anionic surfactant. A new chelating agent (2-((E)-2-amino-4,5-dinitrophenylimino)methyl)phenol) was synthesized and used to form a very stable complex with Pb2+ ions. The lead ions formed complexes and were quantitatively extracted with SDS-coated magnetite nanoparticles. After magnetic separation of adsorbent, the adsorbent was eluted with 0.5% (v/v) HC1 in dimethyl sulfoxide (DMSO) prior to analysis by flame atomic absorption spectrometry (FAAS). Orthogonal array design (OAD) was used to study and optimize the different experimental parameters. Under the optimum conditions, enhancement factor up to 63.5 was achieved for extraction from only 10 mL of sample solution and the relative standard deviation (RSD %) of the method was lower than 2.8%. The obtained calibration curve was linear in the range of 1-300 pg L-' with reasonable linearity (r2 > 0.998). The limit of detection (LOD) based on S/N = 3 was 0.04 microg L(-1) for 10 mL sample volumes. Finally, applicability of the proposed method was successfully confirmed by preconcentration and determination of trace amounts of lead ions in environmental samples and satisfactory results were obtained.

Direct write electron beam lithography: a historical overview

NASA Astrophysics Data System (ADS)

Pfeiffer, Hans C.

2010-09-01

Maskless pattern generation capability in combination with practically limitless resolution made probe-forming electron beam systems attractive tools in the semiconductor fabrication process. However, serial exposure of pattern elements with a scanning beam is a slow process and throughput presented a key challenge in electron beam lithography from the beginning. To meet this challenge imaging concepts with increasing exposure efficiency have been developed projecting ever larger number of pixels in parallel. This evolution started in the 1960s with the SEM-type Gaussian beam systems writing one pixel at a time directly on wafers. During the 1970s IBM pioneered the concept of shaped beams containing multiple pixels which led to higher throughput and an early success of e-beam direct write (EBDW) in large scale manufacturing of semiconductor chips. EBDW in a mix-and match approach with optical lithography provided unique flexibility in part number management and cycle time reduction and proved extremely cost effective in IBM's Quick-Turn-Around-Time (QTAT) facilities. But shaped beams did not keep pace with Moore's law because of limitations imposed by the physics of charged particles: Coulomb interactions between beam electrons cause image blur and consequently limit beam current and throughput. A new technology approach was needed. Physically separating beam electrons into multiple beamlets to reduce Coulomb interaction led to the development of massively parallel projection of pixels. Electron projection lithography (EPL) - a mask based imaging technique emulating optical steppers - was pursued during the 1990s by Bell Labs with SCALPEL and by IBM with PREVAIL in partnership with Nikon. In 2003 Nikon shipped the first NCR-EB1A e-beam stepper based on the PREVAIL technology to Selete. It exposed pattern segments containing 10 million pixels in single shot and represented the first successful demonstration of massively parallel pixel projection. However the window of opportunity for EPL had closed with the quick implementation of immersion lithography and the interest of the industry has since shifted back to maskless lithography (ML2). This historical overview of EBDW will highlight opportunities and limitation of the technology with particular focus on technical challenges facing the current ML2 development efforts in Europe and the US. A brief status report and risk assessment of the ML2 approaches will be provided.

Preparations, Properties, and Applications of Periodic Nano Arrays using Anodized Aluminum Oxide and Di-block Copolymer

NASA Astrophysics Data System (ADS)

Noh, Kunbae

2011-12-01

Self-ordered arrangements observed in various materials systems such as anodic aluminum oxide, polystyrene nanoparticles, and block copolymer are of great interest in terms of providing new opportunities in nanofabrication field where lithographic techniques are broadly used in general. Investigations on self-assembled nano arrays to understand how to obtain periodic nano arrays in an efficient yet inexpensive way, and how to realize advanced material and device systems thereof, can lead to significant impacts on science and technology for many forefront device applications. In this thesis, various aspects of periodic nano-arrays have been discussed including novel preparations, properties and applications of anodized aluminum oxide (AAO) and PS-b-P4VP (S4VP) di-block copolymer self-assembly. First, long-range ordered AAO arrays have been demonstrated. Nanoimprint lithography (NIL) process allowed a faithful pattern transfer of the imprint mold pattern onto Al thin film, and interesting self-healing and pattern tripling phenomena were observed, which could be applicable towards fabrication of the NIL master mold having highly dense pattern over large area, useful for fabrication of a large-area substrate for predictable positioning of arrayed devices. Second, S4VP diblock copolymer self-assembly and S4VP directed AAO self-assembly have been demonstrated in the Al thin film on Si substrate. Such a novel combination of two dissimilar self-assembly techniques demonstrated a potential as a versatile tool for nanopatterning formation on a Si substrate, capable of being integrated into Si process technology. As exemplary applications, vertically aligned Ni nanowires have been synthesized into an S4VP-guided AAO membrane on a Si substrate in addition to anti-dot structured [Co/Pd]n magnetic multilayer using S4VP self assembly. Third, a highly hexagonally ordered, vertically parallel aluminum oxide nanotube array was successfully fabricated via hard anodization technique. The Al2O3 nanotube arrays so fabricated exhibit a uniform and reproducible dimension, and a quite high aspect ratio of greater than ˜1,000. Such high-aspect-ratio, mechanically robust, large-surface-area nanotube array structure can be useful for many technical applications. As a potential application in biomedical research, drug storage/controlled drug release from such AAO nanotubes was investigated, and the advantageous potential of using AAO nanotubes for biological implant surface coatings alternative to TiO2 nanotubes has been discussed.

Binary cobalt ferrite nanomesh arrays as the advanced binder-free electrode for applications in oxygen evolution reaction and supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Li; Zhang, Huijuan; Mu, Yanping; Bai, Yuanjuan; Wang, Yu

2016-09-01

The porous CoFe2O4nanomesh arrays are successfully synthesized on nickel foam substrate through a high temperature and pressure hydrothermal method, following by the thermal post-treatment in air. The CoFe2O4 nanomesh arrays own numerous pores and large specific surface area, which is in favor of exposing more active sites. In consideration of the structural preponderances and versatility of the materials, the CoFe2O4 nanomesh arrays have been researched as the binder-free electrode materials for electrocatalysis and supercapacitors. When the CoFe2O4nanomesh arrays on nickel foam (CoFe2O4 NM-As/Ni) directly act as the free-binder catalyst toward catalyzing the oxygen evolution reaction (OER) of electrochemical water splitting, CoFe2O4 NM-As/Ni exhibits an admirable OER property with a low onset potential of 1.47 V(corresponding to the onset overpotential of 240 mV), a minimal overpotential (η10 = 253 mV), a small Tafel slope (44 mV dec-1), large anodic currents and long-term durability for 35 h in alkaline media. In addition, as an electrode of supercapacitors, CoFe2O4 NM-As/Ni obtains a desired specific capacitance (1426 F/g at the current density of 1 A/g), remarkable rate capability (1024 F/g at the current density of 20 A/g) and eminent capacitance retention (92.6% after 3000 cycles). The above results demonstrate the CoFe2O4 NM-As/Ni possesses great potential application in electrocatalysis and supercapacitors.

The Precision Array for Probing the Epoch of Re-ionization: Eight Station Results

NASA Astrophysics Data System (ADS)

Parsons, Aaron R.; Backer, Donald C.; Foster, Griffin S.; Wright, Melvyn C. H.; Bradley, Richard F.; Gugliucci, Nicole E.; Parashare, Chaitali R.; Benoit, Erin E.; Aguirre, James E.; Jacobs, Daniel C.; Carilli, Chris L.; Herne, David; Lynch, Mervyn J.; Manley, Jason R.; Werthimer, Daniel J.

2010-04-01

We are developing the Precision Array for Probing the Epoch of Re-ionization (PAPER) to detect 21 cm emission from the early universe, when the first stars and galaxies were forming. We describe the overall experiment strategy and architecture and summarize two PAPER deployments: a four-antenna array in the low radio frequency interference (RFI) environment of Western Australia and an eight-antenna array at a prototyping site at the NRAO facilities near Green Bank, WV. From these activities we report on system performance, including primary beam model verification, dependence of system gain on ambient temperature, measurements of receiver and overall system temperatures, and characterization of the RFI environment at each deployment site. We present an all-sky map synthesized between 139 MHz and 174 MHz using data from both arrays that reaches down to 80 mJy (4.9 K, for a beam size of 2.15e-5 sr at 156 MHz), with a 10 mJy (620 mK) thermal noise level that indicates what would be achievable with better foreground subtraction. We calculate angular power spectra (C ell) in a cold patch and determine them to be dominated by point sources, but with contributions from galactic synchrotron emission at lower radio frequencies and angular wavemodes. Although the sample variance of foregrounds dominates errors in these power spectra, we measure a thermal noise level of 310 mK at ell = 100 for a 1.46 MHz band centered at 164.5 MHz. This sensitivity level is approximately 3 orders of magnitude in temperature above the level of the fluctuations in 21 cm emission associated with re-ionization.

Developing high coercivity in large diameter cobalt nanowire arrays

NASA Astrophysics Data System (ADS)

Montazer, A. H.; Ramazani, A.; Almasi Kashi, M.; Zavašnik, J.

2016-11-01

Regardless of the synthetic method, developing high magnetic coercivity in ferromagnetic nanowires (NWs) with large diameters has been a challenge over the past two decades. Here, we report on the synthesis of highly coercive cobalt NW arrays with diameters of 65 and 80 nm, which are embedded in porous anodic alumina templates with high-aspect-ratio pores. Using a modified electrochemical deposition method enabled us to reach room temperature coercivity and remanent ratio up to 3000 Oe and 0.70, respectively, for highly crystalline as-synthesized hcp cobalt NW arrays with a length of 8 μm. The first-order reversal curve (FORC) analysis showed the presence of both soft and hard magnetic phases along the length of the resulting NWs. To develop higher coercive fields, the length of the NWs was then gradually reduced in order from bottom to top, thereby reaching NW sections governed by the hard phase. Consequently, this resulted in record high coercivities of 4200 and 3850 Oe at NW diameters of 65 and 80 nm, respectively. In this case, the FORC diagrams confirmed a significant reduction in interactions between the magnetic phases of the remaining sections of NWs. At this stage, x-ray diffraction (XRD) and dark-field transmission electron microscopy analyses indicated the formation of highly crystalline bamboo-like sections along the [0 0 2] direction during a progressive pulse-controlled electrochemical growth of NW arrays under optimized parameters. Our results both provide new insights into the growth process, crystalline characteristics and magnetic phases along the length of large diameter NW arrays and, furthermore, develop the performance of pure 3d transition magnetic NWs.

Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

2015-10-01

High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg-1), a high power density (27.5 kW kg-1) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg-1), a high power density (27.5 kW kg-1) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs. Electronic supplementary information (ESI) available: SEM images, XPS spectra, equivalent circuit, and CVs. See DOI: 10.1039/c5nr04449a

Three-dimensional hierarchical NiCo2O4 nanowire@Ni3S2 nanosheet core/shell arrays for flexible asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Bo; Kong, Dezhi; Huang, Zhi Xiang; Mo, Runwei; Wang, Ye; Han, Zhaojun; Cheng, Chuanwei; Yang, Hui Ying

2016-05-01

Three-dimensional (3D) hierarchical NiCo2O4@Ni3S2 core/shell arrays on Ni foam were synthesized by a facile, stepwise synthesis approach. The 3D heterogeneous NiCo2O4 nanostructure forms an interconnected web-like scaffold and serves as the core for the Ni3S2 shell. The as-prepared NiCo2O4@Ni3S2 nanowire array (NWA) electrodes exhibited excellent electrochemical performance, such as high specific areal capacitance and excellent cycling stability. The specific areal capacitance of 3.0 F cm-2 at a current density of 5 mA cm-2 is among the highest values and the only 6.7% capacitance decay after 10 000 cycles demonstrates the excellent cycling stability. A flexible asymmetric supercapacitor (ASC) was fabricated with activated carbon (AC) as the anode and the obtained NiCo2O4@Ni3S2 NWAs as the cathode. The ASC device exhibited a high energy density of 1.89 mW h cm-3 at 5.81 W cm-3 and a high power density of 56.33 W cm-3 at 0.94 mW h cm-3. As a result, the hybrid nanoarchitecture opens a new way to design high performance electrodes for electrochemical energy storage applications.Three-dimensional (3D) hierarchical NiCo2O4@Ni3S2 core/shell arrays on Ni foam were synthesized by a facile, stepwise synthesis approach. The 3D heterogeneous NiCo2O4 nanostructure forms an interconnected web-like scaffold and serves as the core for the Ni3S2 shell. The as-prepared NiCo2O4@Ni3S2 nanowire array (NWA) electrodes exhibited excellent electrochemical performance, such as high specific areal capacitance and excellent cycling stability. The specific areal capacitance of 3.0 F cm-2 at a current density of 5 mA cm-2 is among the highest values and the only 6.7% capacitance decay after 10 000 cycles demonstrates the excellent cycling stability. A flexible asymmetric supercapacitor (ASC) was fabricated with activated carbon (AC) as the anode and the obtained NiCo2O4@Ni3S2 NWAs as the cathode. The ASC device exhibited a high energy density of 1.89 mW h cm-3 at 5.81 W cm-3 and a high power density of 56.33 W cm-3 at 0.94 mW h cm-3. As a result, the hybrid nanoarchitecture opens a new way to design high performance electrodes for electrochemical energy storage applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02600a

Heat-enhanced peptide synthesis on Teflon-patterned paper.

PubMed

Deiss, Frédérique; Yang, Yang; Matochko, Wadim L; Derda, Ratmir

2016-06-14

In this report, we describe the methodology for 96 parallel organic syntheses of peptides on Teflon-patterned paper assisted by heating with an infra-red lamp. SPOT synthesis is an important technology for production of peptide arrays on a paper-based support for rapid identification of peptide ligands, epitope mapping, and identification of bio-conjugation reactions. The major drawback of the SPOT synthesis methodology published to-date is suboptimal reaction conversion due to mass transport limitations in the unmixed reaction spot. The technology developed in this report overcomes these problems by changing the environment of the reaction from static to dynamic (flow-through), and further accelerating the reaction by selective heating of the reaction support in contact with activated amino acids. Patterning paper with Teflon allows for droplets of organic solvents to be confined in a zone on the paper array and flow through the paper at a well-defined rate and provide a convenient, power-free setup for flow-through solid-phase synthesis and efficient assembly of peptide arrays. We employed an infra-red (IR) lamp to locally heat the cellulosic support during the flow-through delivery of the reagents to each zone of the paper-based array. We demonstrate that IR-heating in solid phase peptide synthesis shortened the reaction time necessary for amide bond formation down to 3 minutes; in some couplings of alpha amino acids, conversion rates increased up to fifteen folds. The IR-heating improved the assembly of difficult sequences, such as homo-oligomers of all 20 natural amino acids.

Rapid Synthesis of Thin and Long Mo17O47 Nanowire-Arrays in an Oxygen Deficient Flame

PubMed Central

Allen, Patrick; Cai, Lili; Zhou, Lite; Zhao, Chenqi; Rao, Pratap M.

2016-01-01

Mo17O47 nanowire-arrays are promising active materials and electrically-conductive supports for batteries and other devices. While high surface area resulting from long, thin, densely packed nanowires generally leads to improved performance in a wide variety of applications, the Mo17O47 nanowire-arrays synthesized previously by electrically-heated chemical vapor deposition under vacuum conditions were relatively thick and short. Here, we demonstrate a method to grow significantly thinner and longer, densely packed, high-purity Mo17O47 nanowire-arrays with diameters of 20–60 nm and lengths of 4–6 μm on metal foil substrates using rapid atmospheric flame vapor deposition without any chamber or walls. The atmospheric pressure and 1000 °C evaporation temperature resulted in smaller diameters, longer lengths and order-of-magnitude faster growth rate than previously demonstrated. As explained by kinetic and thermodynamic calculations, the selective synthesis of high-purity Mo17O47 nanowires is achieved due to low oxygen partial pressure in the flame products as a result of the high ratio of fuel to oxidizer supplied to the flame, which enables the correct ratio of MoO2 and MoO3 vapor concentrations for the growth of Mo17O47. This flame synthesis method is therefore a promising route for the growth of composition-controlled one-dimensional metal oxide nanomaterials for many applications. PMID:27271194

Electrochemical growth of controlled tip shapes of ZnO nanorod arrays on silicon substrate and enhanced photoluminescence emission from nanopyramid arrays compared with flat-head nanorods

NASA Astrophysics Data System (ADS)

Alimanesh, Mahmoud; Hassan, Z.; Zainal, Norzaini

2017-10-01

Zinc oxide (ZnO) nanorod arrays (NRAs) with different morphologies such as; perfect hexagon flat-head, pyramidal, compact pencil, nail-shaped, and high-compact ZnO nanorod thin films, were successfully grown on silicon substrates. These NRAs were formed on substrates using a simple low-temperature electrochemical method without adding any catalyst or template via the precursors of zinc nitrate hexahydrate [Zn(NO3)2·6H2O] and hexamethylenetetramine [HMT; C6H12N4] with an equal molar concentration of 0.025 mol/l. The morphologies of the ZnO nanorods (NRs) could be controlled and transformed successfully in to other morphologies by changing the growth conditions, such as; growth temperature and applied current density. Detailed structural investigations reveal that the synthesized various NRs are single crystalline with wurtzite hexagonal phase and preferentially grow along the c-axis direction. The room temperature photoluminescence spectra show that each spectrum consists of an ultraviolet (UV) band and a relative broad visible light emission and infrared emission peak. The enhanced light emission intensity at UV peak (∼375 nm) is observed significantly from ZnO nanopyramid (NP) arrays because of the conical shape of NP. The photoluminescence intensity of the UV peak from the NPs is found to be 1.5-17 times larger than those from the other various NRs.

Zinc cobalt sulfide nanosheets array derived from 2D bimetallic metal-organic frameworks for high-performance supercapacitor.

PubMed

Tao, Kai; Han, Xue; Cheng, Qiuhui; Yang, Yujing; Yang, Zheng; Ma, Qingxiang; Han, Lei

2018-04-19

Porous ternary metal sulfide integrated electrode materials with abundant electroactive sites and redox reactions are very promising for supercapacitors. Here, porous zinc cobalt sulfide nanosheets array on Ni foam (Zn-Co-S/NF) has been successfully constructed by a facile growth of 2D bimetallic zinc/cobalt-based metal-organic frameworks (Zn/Co-MOF) nanosheets with leaf-like morphology on Ni foam, followed by additional sulfurization. The Zn-Co-S/NF nanosheets array is directly acted as an electrode for supercapacitor, showing much better electrochemical performance (2354.3 F g-1 and 88.6% retention over 1000 cycles) when compared with zinc cobalt sulfide powder (355.3 F g-1 and 75.8% retention over 1000 cycles), which is originated from good electric conductivity and mechanical stability, abundant electroactive sites, and facilitated transportation of electron and electrolyte ion endowed by the unique nanosheets array structure. The asymmetric supercapacitor (ASC) device assembled from Zn-Co-S/NF and activated carbon electrodes can deliver the highest energy density of 31.9 Wh kg-1 and the maximum power density of 8.5 kW kg-1. Most importantly, this ASC also presents good cycling stability (97% retention over 1000 cycles). Furthermore, a red light-emitting diode (LED) can be illuminated by two connected ASCs, indicating that as-synthesized Zn-Co-S/NF hold great potential for practical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rational Design of Self-Supported Ni3S2 Nanosheets Array for Advanced Asymmetric Supercapacitor with a Superior Energy Density.

PubMed

Chen, Jun Song; Guan, Cao; Gui, Yang; Blackwood, Daniel John

2017-01-11

We report a rationally designed two-step method to fabricate self-supported Ni 3 S 2 nanosheet arrays. We first used 2-methylimidazole (2-MI), an organic molecule commonly served as organic linkers in metal-organic frameworks (MOFs), to synthesize an α-Ni(OH) 2 nanosheet array as a precursor, followed by its hydrothermal sulfidization into Ni 3 S 2 . The resulting Ni 3 S 2 nanosheet array demonstrated superior supercapacitance properties, with a very high capacitance of about 1,000 F g -1 being delivered at a high current density of 50 A g -1 for 20,000 charge-discharge cycles. This performance is unparalleled by other reported nickel sulfide-based supercapacitors and is also advantageous compared to other nickel-based materials such as NiO and Ni(OH) 2 . An asymmetric supercapacitor was then established, exhibiting a very stable capacitance of about 200 F g -1 at a high current density of 10 A g -1 for 10,000 cycles and a surprisingly high energy density of 202 W h kg -1 . This value is comparable to that of the lithium-ion batteries, i.e., 180 W h kg -1 . The potential of the material for practical applications was evaluated by building a quasi-solid-state asymmetric supercapacitor which showed good flexibility and power output, and two of these devices connected in series were able to power up 18 green light-emitting diodes.

Optimization of peptide arrays for studying antibodies to hepatitis C virus continuous epitopes

PubMed Central

Ruwona, Tinashe B; Mcbride, Ryan; Chappel, Rebecca; Head, Steven R; Ordoukhanian, Phillip; Burton, Dennis R.; Law, Mansun

2014-01-01

Accurate and in-depth mapping of antibody responses is of great value in vaccine and antibody research. Using hepatitis C virus (HCV) as a model, we developed an affordable and high-throughput microarray-based assay for mapping antibody specificities to continuous antibody epitopes of HCV at high resolution. Important parameters in the chemistry for conjugating peptides/antigens to the array surface, the array layout, fluorophore choice and the methods for data analysis were investigated. Microscopic glass slide pre-coated with N-Hydroxysuccinimide (NHS)-ester (Slide H) was the preferred surface for conjugation of aminooxy-tagged peptides. This combination provides a simple chemical means to orient the peptides to the conjugation surface via an orthogonal covalent linkage at the N- or C-terminus of each peptide. The addition of polyvinyl alcohol to printing buffer gave uniform spot morphology, improved sensitivity and specificity of binding signals. Libraries of overlapping peptides covering the HCV E1 and E2 glycoprotein polypeptides (15-mer, 10 amino acids overlap) of 6 major HCV genotypes and the entire polypeptide sequence of the prototypic strain H77 were synthesized and printed in quadruplets in the assays. The utility of the peptide arrays were confirmed using HCV monoclonal antibodies (mAbs) specific to known continuous epitopes and immune sera of rabbits immunized with HCV antigens. The methods developed here can be easily adapted to studying antibody responses to antigens relevant in vaccine and autoimmune research. PMID:24269751

Experimental, theoretical, and device application development of nanoscale focused electron-beam-induced deposition

NASA Astrophysics Data System (ADS)

Randolph, Steven Jeffrey

Electron-beam-induced deposition (EBID) is a highly versatile nanofabrication technique that allows for growth of a variety of materials with nanoscale precision and resolution. While several applications and studies of EBID have been reported and published, there is still a significant lack of understanding of the complex mechanisms involved in the process. Consequently, EBID process control is, in general, limited and certain common experimental results regarding nanofiber growth have yet to be fully explained. Such anomalous results have been addressed in this work both experimentally and by computer simulation. Specifically, a correlation between SiOx nanofiber deposition observations and the phenomenon of electron beam heating (EBH) was shown by comparison of thermal computer models and experimental results. Depending on the beam energy, beam current, and nanostructure geometry, the heat generated can be substantial and may influence the deposition rate. Temperature dependent EBID growth experiments qualitatively verified the results of the EBH model. Additionally, EBID was used to produce surface image layers for maskless, direct-write lithography (MDL). A single layer process used directly written SiOx features as a masking layer for amorphous silicon thin films. A bilayer process implemented a secondary masking layer consisting of standard photoresist into which a pattern---directly written by EBID tungsten---was transferred. The single layer process was found to be extremely sensitive to the etch selectivity of the plasma etch. In the bilayer process, EBID tungsten was written onto photoresist and the pattern transferred by means of oxygen plasma dry development following a brief refractory descum. Conditions were developed to reduce the spatial spread of electrons in the photoresist layer and obtain ˜ 35 nm lines. Finally, an EBID-based technique for field emitter repair was applied to the Digital Electrostatically focused e-beam Array Lithography (DEAL) parallel electron beam lithography configuration to repair damaged or missing carbon nanofiber cathodes. The I-V response and lithography results from EBID tungsten-based devices were comparable to CNF-based DEAL devices indicating a successful repair technique.

Two-dimensional ultrahigh-density X-ray optical memory.

PubMed

Bezirganyan, Hakob P; Bezirganyan, Siranush E; Bezirganyan, Hayk H; Bezirganyan, Petros H

2007-01-01

Most important aspect of nanotechnology applications in the information ultrahigh storage is the miniaturization of data carrier elements of the storage media with emphasis on the long-term stability. Proposed two-dimensional ultrahigh-density X-ray optical memory, named X-ROM, with long-term stability is an information carrier basically destined for digital data archiving. X-ROM is a semiconductor wafer, in which the high-reflectivity nanosized X-ray mirrors are embedded. Data are encoded due to certain positions of the mirrors. Ultrahigh-density data recording procedure can e.g., be performed via mask-less zone-plate-array lithography (ZPAL), spatial-phase-locked electron-beam lithography (SPLEBL), or focused ion-beam lithography (FIB). X-ROM manufactured by nanolithography technique is a write-once memory useful for terabit-scale memory applications, if the surface area of the smallest recording pits is less than 100 nm2. In this case the X-ROM surface-storage capacity of a square centimetre becomes by two orders of magnitude higher than the volumetric data density really achieved for three-dimensional optical data storage medium. Digital data read-out procedure from proposed X-ROM can e.g., be performed via glancing-angle incident X-ray micro beam (GIX) using the well-developed X-ray reflectometry technique. In presented theoretical paper the crystal-analyser operating like an image magnifier is added to the set-up of X-ROM data handling system for the purpose analogous to case of application the higher numerical aperture objective in optical data read-out system. We also propose the set-up of the X-ROM readout system based on more the one incident X-ray micro beam. Presented scheme of two-beam data handling system, which operates on two mutually perpendicular well-collimated monochromatic incident X-ray micro beams, essentially increases the reliability of the digital information read-out procedure. According the graphs of characteristic functions presented in paper, one may choose optimally the incident radiation wavelength, as well as the angle of incidence of X-ray micro beams, appropriate for proposed digital data read-out procedure.

One-Step Formation of WO3-Loaded TiO2 Nanotubes Composite Film for High Photocatalytic Performance

PubMed Central

Lee, Wai Hong; Lai, Chin Wei; Abd Hamid, Sharifah Bee

2015-01-01

High aspect ratio of WO3-loaded TiO2 nanotube arrays have been successfully synthesized using the electrochemical anodization method in an ethylene glycol electrolyte containing 0.5 wt% ammonium fluoride in a range of applied voltage of 10–40 V for 30 min. The novelty of this research works in the one-step formation of WO3-loaded TiO2 nanotube arrays composite film by using tungsten as the cathode material instead of the conventionally used platinum electrode. As compared with platinum, tungsten metal has lower stability, forming dissolved ions (W6+) in the electrolyte. The W6+ ions then move towards the titanium foil and form a coherent deposit on titanium foil. By controlling the oxidation rate and chemical dissolution rate of TiO2 during the electrochemical anodization, the nanotubular structure of TiO2 film could be achieved. In the present study, nanotube arrays were characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the results obtained, nanotube arrays with average pore diameter of up to 74 nm and length of 1.6 µm were produced. EDAX confirmed the presence of tungsten element within the nanotube arrays which varied in content from 1.06 at% to 3.29 at%. The photocatalytic activity of the nanotube arrays was then investigated using methyl orange degradation under TUV 96W UV-B Germicidal light irradiation. The nanotube with the highest aspect ratio, geometric surface area factor and at% of tungsten exhibited the highest photocatalytic activity due to more photo-induced electron-hole pairs generated by the larger surface area and because WO3 improves charge separation, reduces charge carrier recombination and increases charge carrier lifetime via accumulation of electrons and holes in the two different metal oxide semiconductor components.

Development of magnetic luminescent core/shell nanocomplex particles with fluorescence using Rhodamine 6G

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hee Uk; Song, Yoon Seok; Park, Chulhwan

2012-12-15

Graphical abstract: Display Omitted Highlights: ► A simple method was developed to synthesize Co-B/SiO{sub 2}/dye/SiO{sub 2} composite particles. ► The magnetic particle shows that highly luminescent and core/shell particles are formed. ► Such core/shell particles can be easily suspended in water. ► The magnetic particles could detect fluorescence for the application of biosensor. -- Abstract: A simple and reproducible method was developed to synthesize a novel class of Co-B/SiO{sub 2}/dye/SiO{sub 2} composite core/shell particles. Using a single cobalt core, Rhodamine 6G of organic dye molecules was entrapped in a silica shell, resulting in core/shell particles of ∼200 nm diameter. Analysesmore » using a variety of techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, vibration sample magnetometry, confocal laser scanning microscopy, and fluorescence intensity demonstrated that dye molecules were trapped inside the core/shell particles. A photoluminescence investigation showed that highly luminescent and photostable core/shell particles were formed. Such core/shell particles can be easily suspended in water. The synthesized magnetic particles could be used to detect fluorescence on glass substrate arrays for bioassay and biosensor applications.« less

CdTe quantum-dot-modified ZnO nanowire heterostructure

NASA Astrophysics Data System (ADS)

Shahi, Kanchana; Singh, R. S.; Singh, Ajaya Kumar; Aleksandrova, Mariya; Khenata, Rabah

2018-03-01

The effect of CdTe quantum-dot (QD) decoration on the photoluminescence (PL) behaviour of ZnO nanowire (NW) array is presented in the present work. Highly crystalline and vertically 40-50 nm diameter range and 1 µm in length aligned ZnO NWs are synthesized using low-cost method. The crystallinity and morphology of the NWs are studied by scanning electron microscopy and X-ray powder diffraction methods.Optical properties of the nanowires are studied using photo-response and PL spectroscopy. CdTe QDs are successfully synthesized on ZnO nanowire surface by dip-coating method. ZnO NWs are sensitized with CdTe QDs characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and PL spectroscopy. The highly quenched PL intensity indicates the charge transfer at interface between CdTe QDs and ZnO NWs and is due to the formation of type-II heterostructure between QDs and NWs. Photo-response behaviour of heterostructure of the film is also been incorporated in the present work.

Anatase TiO2 ultrathin nanobelts derived from room-temperature-synthesized titanates for fast and safe lithium storage

PubMed Central

Wen, Wei; Wu, Jin-ming; Jiang, Yin-zhu; Yu, Sheng-lan; Bai, Jun-qiang; Cao, Min-hua; Cui, Jie

2015-01-01

Lithium-ion batteries (LIBs) are promising energy storage devices for portable electronics, electric vehicles, and power-grid applications. It is highly desirable yet challenging to develop a simple and scalable method for constructions of sustainable materials for fast and safe LIBs. Herein, we exploit a novel and scalable route to synthesize ultrathin nanobelts of anatase TiO2, which is resource abundant and is eligible for safe anodes in LIBs. The achieved ultrathin nanobelts demonstrate outstanding performances for lithium storage because of the unique nanoarchitecture and appropriate composition. Unlike conventional alkali-hydrothermal approaches to hydrogen titanates, the present room temperature alkaline-free wet chemistry strategy guarantees the ultrathin thickness for the resultant titanate nanobelts. The anatase TiO2 ultrathin nanobelts were achieved simply by a subsequent calcination in air. The synthesis route is convenient for metal decoration and also for fabricating thin films of one/three dimensional arrays on various substrates at low temperatures, in absence of any seed layers. PMID:26133276

Synthesis, Spectral Characterization, In-vitro Antibacterial and Antifungal Activities of Novel (2e)-Ethyl-2-(2-(2, 4-Dinitrophenyl) Hydrazono)-4-(Naphthalen-2-yl)-6-Arylcyclohex-3-Enecarboxylates

PubMed Central

Kanagarajan, V; Thanusu, J; Gopalakrishnan, M

2011-01-01

In a search for new leads towards potent antimicrobial agents, an array of novel (2E)-ethyl-2-(2-(2,4-dinitrophenyl)hydrazono)-4-(naphthalen-2-yl)-6-arylcyclohex-3-ene carboxylates 17-24 were synthesized and characterized through their melting point, elemental analysis, MS, FT-IR, one-dimensional NMR (1H, D2O exchanged 1H and 13C), two dimensional HOMOCOR and HSQC spectroscopic data. In-vitro microbiological evaluations were carried out for all the newly synthesized compounds 17-24 against clinically isolated bacterial strains namely Salmonella typhii, Klebsiellapneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, β-Hemolytic streptococcus and Micrococcus luteusand also fungal strains namely Aspergillusflavus, Aspergillusniger, Mucor, Rhizopus and Microsporumgypseumand finally, the results of their structure activity relationship were discussed. The obtained results can be used as the key step for the building of novel chemical compounds with interesting antimicrobial profiles comparable to that of the standard drugs. PMID:24250406

Synthesis, Spectral Characterization, In-vitro Antibacterial and Antifungal Activities of Novel (2e)-Ethyl-2-(2-(2, 4-Dinitrophenyl) Hydrazono)-4-(Naphthalen-2-yl)-6-Arylcyclohex-3-Enecarboxylates.

PubMed

Kanagarajan, V; Thanusu, J; Gopalakrishnan, M

2011-01-01

In a search for new leads towards potent antimicrobial agents, an array of novel (2E)-ethyl-2-(2-(2,4-dinitrophenyl)hydrazono)-4-(naphthalen-2-yl)-6-arylcyclohex-3-ene carboxylates 17-24 were synthesized and characterized through their melting point, elemental analysis, MS, FT-IR, one-dimensional NMR ((1)H, D2O exchanged (1)H and (13)C), two dimensional HOMOCOR and HSQC spectroscopic data. In-vitro microbiological evaluations were carried out for all the newly synthesized compounds 17-24 against clinically isolated bacterial strains namely Salmonella typhii, Klebsiellapneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, β-Hemolytic streptococcus and Micrococcus luteusand also fungal strains namely Aspergillusflavus, Aspergillusniger, Mucor, Rhizopus and Microsporumgypseumand finally, the results of their structure activity relationship were discussed. The obtained results can be used as the key step for the building of novel chemical compounds with interesting antimicrobial profiles comparable to that of the standard drugs.

Hybrid NiS/CoO mesoporous nanosheet arrays on Ni foam for high-rate supercapacitors

NASA Astrophysics Data System (ADS)

Wu, Jianghong; Ouyang, Canbin; Dou, Shuo; Wang, Shuangyin

2015-08-01

A new hybrid of NiS/CoO porous nanosheets was synthesized on Ni foam by one-step electrodeposition method and used as an electrode for high-performance pseudocapacitance. The as-synthesized NiS/CoO porous nanosheets hybrid shows a high specific capacitance of 1054 F g-1 at a high current density of 6 A g-1, a good rate capability even at high current density (760 F g-1 at 20 A g-1) and a good long-term cycling stability (91.7% of the maximum specific capacitance after 3000 cycles). These excellent properties can be mainly attributed to the unique hierarchical porous structure with large surface area and interspaces which facilitate charge transfer and redox reaction. The enhancement in the interface contact between active material and substrate results in excellent conductivity of the electrode and a strong synergistic effect of NiS and CoO as individual constituents contributed to high capacitance of the hybrid electrode.

Hybrid NiS/CoO mesoporous nanosheet arrays on Ni foam for high-rate supercapacitors.

PubMed

Wu, Jianghong; Ouyang, Canbin; Dou, Shuo; Wang, Shuangyin

2015-08-14

A new hybrid of NiS/CoO porous nanosheets was synthesized on Ni foam by one-step electrodeposition method and used as an electrode for high-performance pseudocapacitance. The as-synthesized NiS/CoO porous nanosheets hybrid shows a high specific capacitance of 1054 F g(-1) at a high current density of 6 A g(-1), a good rate capability even at high current density (760 F g(-1) at 20 A g(-1)) and a good long-term cycling stability (91.7% of the maximum specific capacitance after 3000 cycles). These excellent properties can be mainly attributed to the unique hierarchical porous structure with large surface area and interspaces which facilitate charge transfer and redox reaction. The enhancement in the interface contact between active material and substrate results in excellent conductivity of the electrode and a strong synergistic effect of NiS and CoO as individual constituents contributed to high capacitance of the hybrid electrode.

Asymmetric Suzuki-Miyaura coupling of heterocycles via Rhodium-catalysed allylic arylation of racemates

PubMed Central

Schäfer, Philipp; Palacin, Thomas; Sidera, Mireia; Fletcher, Stephen P.

2017-01-01

Using asymmetric catalysis to simultaneously form carbon–carbon bonds and generate single isomer products is strategically important. Suzuki-Miyaura cross-coupling is widely used in the academic and industrial sectors to synthesize drugs, agrochemicals and biologically active and advanced materials. However, widely applicable enantioselective Suzuki-Miyaura variations to provide 3D molecules remain elusive. Here we report a rhodium-catalysed asymmetric Suzuki-Miyaura reaction with important partners including aryls, vinyls, heteroaromatics and heterocycles. The method can be used to couple two heterocyclic species so the highly enantioenriched products have a wide array of cores. We show that pyridine boronic acids are unsuitable, but they can be halogen-modified at the 2-position to undergo reaction, and this halogen can then be removed or used to facilitate further reactions. The method is used to synthesize isoanabasine, preclamol, and niraparib—an anticancer agent in several clinical trials. We anticipate this method will be a useful tool in drug synthesis and discovery. PMID:28607510

Enrichment of peptides in serum by C(8)-functionalized magnetic nanoparticles for direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis.

PubMed

Yao, Ning; Chen, Hemei; Lin, Huaqing; Deng, Chunhui; Zhang, Xiangmin

2008-03-21

Human serum contains a complex array of proteolytically derived peptides (serum peptidome), which contain biomarkers of preclinical screening and disease diagnosis. Recently, commercial C(8)-functionalized magnetic beads (1-10 microm) were widely applied to the separation and enrichment of peptides in human serum, prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. In this work, laboratory-prepared C(8)-functionalized magnetic nanoparticles (about 50 nm) were prepared and applied to the fast separation and the enrichment of peptides from serum. At first, the C(8)-magnetic nanoparticles were synthesized by modifying amine-functionalized magnetic nanoparticles with chlorodimethyloctylsilane. These synthesized C(8)-amine-functionalized magnetic particles have excellent magnetic responsibility, high dispersibility and large surface area. Finally, the C(8)-magnetic nanoparticles were successfully applied to fast and efficient enrichment of low-abundance peptides from protein tryptic digestion and human serum followed by MALDI-TOF-MS analysis.

Bioinspired Functionalized Melanin Nanovariants with a Range of Properties Provide Effective Color Matched Photoprotection in Skin.

PubMed

Vij, Manika; Grover, Ritika; Gotherwal, Vishvabandhu; Wani, Naiem Ahmad; Joshi, Prashant; Gautam, Hemlata; Sharma, Kanupriya; Chandna, Sudhir; Gokhale, Rajesh S; Rai, Rajkishor; Ganguli, Munia; Natarajan, Vivek T

2016-09-12

Melanin and related polydopamine hold great promise; however, restricted fine-tunabilility limits their usefulness in biocompatible applications. In the present study, by taking a biomimetic approach, we synthesize peptide-derived melanin with a range of physicochemical properties. Characterization of these melanin polymers indicates that they exist as nanorange materials with distinct size distribution, shapes, and surface charges. These variants demonstrate similar absorption spectra but have different optical properties that correlate with particle size. Our approach enables incorporation of chemical groups to create functionalized polyvalent organic nanomaterials and enables customization of melanin. Further, we establish that these synthetic variants are efficiently taken up by the skin keratinocytes, display appreciable photoprotection with minimal cytotoxicity, and thereby function as effective color matched photoprotective agents. In effect we demonstrate that an array of functionalized melanins with distinct properties could be synthesized using bioinspired green chemistry, and these are of immense utility in generating customized melanin/polydopamine like materials.

Synthesis, characterization and molecular docking studies of substituted 4-coumarinylpyrano[2,3-c]pyrazole derivatives as potent antibacterial and anti-inflammatory agents.

PubMed

Chougala, Bahubali M; Samundeeswari, S; Holiyachi, Megharaja; Shastri, Lokesh A; Dodamani, Suneel; Jalalpure, Sunil; Dixit, Sheshagiri R; Joshi, Shrinivas D; Sunagar, Vinay A

2017-01-05

A green, eco-friendly and efficient protocol has been developed and synthesized a series of coumarin based pyrano[2,3-c]pyrazole derivatives (3) by multi-component reaction (MCR). Unexpected 3-coumarinyl-3-pyrazolylpropanoic acids (4) have been isolated by the reaction of compound (3) in acidic conditions. Further, intramolecular cyclization of compounds (4) leads to C 4 C 4 chromons (9) and these compounds were screened for their biological activities using array of techniques. Most of the compounds exhibited promising antibacterial activity, in particular Gram-positive bacteria. The anti-inflammatory assay was evaluated against protein denaturation as well as HRBC membrane stabilization methods and compounds exhibit excellent anti-inflammatory activity in both methods. Molecular docking study has been performed for all the synthesized compounds with S. aureus dihydropteroate synthetase (DHPS) and results obtained are quite promising. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Asymmetric Suzuki-Miyaura coupling of heterocycles via Rhodium-catalysed allylic arylation of racemates

NASA Astrophysics Data System (ADS)

Schäfer, Philipp; Palacin, Thomas; Sidera, Mireia; Fletcher, Stephen P.

2017-06-01

Using asymmetric catalysis to simultaneously form carbon-carbon bonds and generate single isomer products is strategically important. Suzuki-Miyaura cross-coupling is widely used in the academic and industrial sectors to synthesize drugs, agrochemicals and biologically active and advanced materials. However, widely applicable enantioselective Suzuki-Miyaura variations to provide 3D molecules remain elusive. Here we report a rhodium-catalysed asymmetric Suzuki-Miyaura reaction with important partners including aryls, vinyls, heteroaromatics and heterocycles. The method can be used to couple two heterocyclic species so the highly enantioenriched products have a wide array of cores. We show that pyridine boronic acids are unsuitable, but they can be halogen-modified at the 2-position to undergo reaction, and this halogen can then be removed or used to facilitate further reactions. The method is used to synthesize isoanabasine, preclamol, and niraparib--an anticancer agent in several clinical trials. We anticipate this method will be a useful tool in drug synthesis and discovery.

Coupled auralization and virtual video for immersive multimedia displays

NASA Astrophysics Data System (ADS)

Henderson, Paul D.; Torres, Rendell R.; Shimizu, Yasushi; Radke, Richard; Lonsway, Brian

2003-04-01

The implementation of maximally-immersive interactive multimedia in exhibit spaces requires not only the presentation of realistic visual imagery but also the creation of a perceptually accurate aural experience. While conventional implementations treat audio and video problems as essentially independent, this research seeks to couple the visual sensory information with dynamic auralization in order to enhance perceptual accuracy. An implemented system has been developed for integrating accurate auralizations with virtual video techniques for both interactive presentation and multi-way communication. The current system utilizes a multi-channel loudspeaker array and real-time signal processing techniques for synthesizing the direct sound, early reflections, and reverberant field excited by a moving sound source whose path may be interactively defined in real-time or derived from coupled video tracking data. In this implementation, any virtual acoustic environment may be synthesized and presented in a perceptually-accurate fashion to many participants over a large listening and viewing area. Subject tests support the hypothesis that the cross-modal coupling of aural and visual displays significantly affects perceptual localization accuracy.

The Effect of Eu Doping on Microstructure, Morphology and Methanal-Sensing Performance of Highly Ordered SnO2 Nanorods Array

PubMed Central

Zhao, Yanping; Li, Yuehua; Ren, Xingping; Gao, Fan; Zhao, Heyun

2017-01-01

Layered Eu-doped SnO2 ordered nanoarrays constructed by nanorods with 10 nm diameters and several hundred nanometers length were synthesized by a substrate-free hydrothermal route using alcohol and water mixed solvent of sodium stannate and sodium hydroxide at 200 °C. The Eu dopant acted as a crystal growth inhibitor to prevent the SnO2 nanorods growth up, resulting in tenuous SnO2 nanorods ordered arrays. The X-ray diffraction (XRD) revealed the tetragonal rutile-type structure with a systematic average size reduction and unit cell volume tumescence, while enhancing the residual strain as the Eu-doped content increases. The surface defects that were caused by the incorporation of Eu ions within the surface oxide matrix were observed by high-resolution transmission electron microscope (HRTEM). The results of the response properties of sensors based on the different levels of Eu-doped SnO2 layered nanoarrays demonstrated that the 0.5 at % Eu-doped SnO2 layered nanorods arrays exhibited an excellent sensing response to methanal at 278 °C. The reasons of the enhanced sensing performance were discussed from the complicated defect surface structure, the large specific surface area, and the excellent catalytic properties of Eu dopant. PMID:29168796

High Discharge Energy Density at Low Electric Field Using an Aligned Titanium Dioxide/Lead Zirconate Titanate Nanowire Array

PubMed Central

Zhang, Dou; Liu, Weiwei; Guo, Ru; Zhou, Kechao

2017-01-01

Abstract Polymer‐based capacitors with high energy density have attracted significant attention in recent years due to their wide range of potential applications in electronic devices. However, the obtained high energy density is predominantly dependent on high applied electric field, e.g., 400–600 kV mm−1, which may bring more challenges relating to the failure probability. Here, a simple two‐step method for synthesizing titanium dioxide/lead zirconate titanate nanowire arrays is exploited and a demonstration of their ability to achieve high discharge energy density capacitors for low operating voltage applications is provided. A high discharge energy density of 6.9 J cm−3 is achieved at low electric fields, i.e., 143 kV mm−1, which is attributed to the high relative permittivity of 218.9 at 1 kHz and high polarization of 23.35 µC cm−2 at this electric field. The discharge energy density obtained in this work is the highest known for a ceramic/polymer nanocomposite at such a low electric field. The novel nanowire arrays used in this work are applicable to a wide range of fields, such as energy harvesting, energy storage, and photocatalysis. PMID:29610724

A Digital Backend for the Low Frequency All Sky Monitor

NASA Astrophysics Data System (ADS)

Dartez, L. P.

2014-04-01

The Low Frequency All Sky Monitor (LoFASM) is a distributed array of dipole antennas that are sensitive to radio frequencies from 10 to 88 MHz. The primary science goals of LoFASM are the detection and study of low-frequency radio transients, a high priority science goal as deemed by the National Research Council's decadal survey. LoFASM consists of antennas and front-end electronics that were originally developed for the Long Wavelength Array (LWA) by the U.S. Naval Research Lab, the University of New Mexico, Virginia Tech, and the Jet Propulsion Laboratory. LoFASM, funded by the U.S. Department of Defense, will initially consist of four stations, each consisting of 12 dual-polarization dipole antennas. In a single station, RF signals from each of the individual LoFASM dipoles are combined in phase in order to synthesize LoFASM's beam. The LoFASM RF signals are phased up so that the resulting beam is sensitive to radio emission that originates from the zenith and RF signals approaching from the horizon are attenuated. Digitally, this is achieved using a full Stokes 100MHz correlating spectrometer constructed using field programmable gate array (FPGA) technology. In this thesis I will describe the design and usage of the LoFASM Correlator.

A gas sensor array for the simultaneous detection of multiple VOCs.

PubMed

Zhang, Yumin; Zhao, Jianhong; Du, Tengfei; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

2017-05-16

Air quality around the globe is declining and public health is seriously threatened by indoor air pollution. Typically, indoor air pollutants are composed of a series of volatile organic compounds (VOCs) that are generally harmful to the human body, especially VOCs with low molecular weights (less than 100 Da). Moreover, in some situations, more than one type of VOC is present; thus, a device that can detect one or more VOCs simultaneously would be most beneficial. Here, we synthesized a sensor array with 4 units to detect 4 VOCs: acetone (unit 1), benzene (unit 2), methanol (unit 3) and formaldehyde (unit 4) simultaneously. All units were simultaneously exposed to 2.5 ppm of all four VOCs. The sensitivity of unit 1 was 14.67 for acetone and less than 2.54 for the other VOCs. The sensitivities of units 2, 3 and 4 to benzene, methanol and formaldehyde were 2 18.64, 20.98 and 17.26, respectively, and less than 4.01 for the other VOCs. These results indicated that the sensor array exhibited good selectivity and could be used for the real-time monitoring of indoor air quality. Thus, this device will be useful in situations requiring the simultaneous detection of multiple VOCs.

Growth of highly textured PbTiO3 films on conductive substrate under hydrothermal conditions

NASA Astrophysics Data System (ADS)

Tang, Haixiong; Zhou, Zhi; Bowland, Christopher C.; Sodano, Henry A.

2015-08-01

Perovskite structure (ABO3) thin films have wide applications in electronic devices due to their unique properties, including high dielectric permittivity, ferroelectricity and piezoelectric coupling. Here, we report an approach to grow highly textured thick lead titanate (PbTiO3) films on conductive substrates by a two-step hydrothermal reaction. Initially, vertically aligned TiO2 nanowire arrays are grown on fluorine-doped tin oxide (FTO) coated glass, which act as template crystals for conversion to the perovskite structure. The PbTiO3 films are then converted from TiO2 NW arrays by diffusing Pb2+ ions into the template through a second hydrothermal reaction. The dielectric permittivity and piezoelectric coupling coefficient (d33) of the PbTiO3 films are as high as 795 at 1 kHz and 52 pm V-1, respectively. The reported process can also potentially be expanded for the assembly of other complex perovskite ATiO3 (A = Ba, Ca, Cd, etc) films by using the highly aligned TiO2 NW arrays as templates. Therefore, the approach introduced here opens up a new door to synthesize ferroelectric thin films on conductive substrates for application in sensors, actuators, and ultrasonic transducers that are important in various industrial and scientific areas.

Room-temperature synthesis of two-dimensional ultrathin gold nanowire parallel array with tunable spacing.

PubMed

Morita, Clara; Tanuma, Hiromitsu; Kawai, Chika; Ito, Yuki; Imura, Yoshiro; Kawai, Takeshi

2013-02-05

A series of long-chain amidoamine derivatives with different alkyl chain lengths (CnAA where n is 12, 14, 16, or 18) were synthesized and studied with regard to their ability to form organogels and to act as soft templates for the production of Au nanomaterials. These compounds were found to self-assemble into lamellar structures and exhibited gelation ability in some apolar solvents. The gelation concentration, gel-sol phase transition temperature, and lattice spacing of the lamellar structures in organic solvent all varied on the basis of the alkyl chain length of the particular CnAA compound employed. The potential for these molecules to function as templates was evaluated through the synthesis of Au nanowires (NWs) in their organogels. Ultrathin Au NWs were obtained from all CnAA/toluene gel systems, each within an optimal temperature range. Interestingly, in the case of C12AA and C14AA, it was possible to fabricate ultrathin Au NWs at room temperature. In addition, two-dimensional parallel arrays of ultrathin Au NWs were self-assembled onto TEM copper grids as a result of the drying of dispersion solutions of these NWs. The use of CnAA compounds with differing alkyl chain lengths enabled precise tuning of the distance between the Au NWs in these arrays.

Crab-shell induced synthesis of ordered macroporous carbon nanofiber arrays coupled with MnCo2O4 nanoparticles as bifunctional oxygen catalysts for rechargeable Zn-air batteries.

PubMed

Bin, Duan; Guo, Ziyang; Tamirat, Andebet Gedamu; Ma, Yuanyuan; Wang, Yonggang; Xia, Yongyao

2017-08-10

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out using noble metals (such as Pt) and metal oxides (such as RuO 2 and IrO 2 ) as catalysts, respectively. Nevertheless, several key issues such as high cost, poor stability, and detrimental environmental effects limit the catalytic activity of these noble metal- and metal oxide-based catalysts. Herein, we have designed and synthesized macroporous carbon nanofiber arrays by using a natural crab shell template. Subsequently, spinel MnCo 2 O 4 nanoparticles were embedded into the nitrogen-doped macroporous carbon nanofiber arrays (NMCNAs) by a hydrothermal method. Accompanied by the good conductivity, large surface area and doping of nitrogen, the as-prepared MnCo 2 O 4 /NMCNA exhibited remarkable catalytic performance and outstanding stability for both ORR and OER in alkaline media. The macroporous superstructures play vital role in reducing the ion transport resistance and facilitating the diffusion of gaseous products (O 2 ). Finally, rechargeable Zn-air batteries using the MnCo 2 O 4 /NMCNA catalyst displayed appreciably lower overpotentials, higher power density and better stability than commercial Pt/C, thus raising the prospect of functional low-cost, non-precious-metal bifunctional catalysts in metal-air batteries.

Highly catalytic and stabilized titanium nitride nanowire array-decorated graphite felt electrodes for all vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Wei, L.; Zhao, T. S.; Zeng, L.; Zeng, Y. K.; Jiang, H. R.

2017-02-01

In this work, we prepare a highly catalytic and stabilized titanium nitride (TiN) nanowire array-decorated graphite felt electrode for all vanadium redox flow batteries (VRFBs). Free-standing TiN nanowires are synthesized by a two-step process, in which TiO2 nanowires are first grown onto the surface of graphite felt via a seed-assisted hydrothermal method and then converted to TiN through nitridation reaction. When applied to VRFBs, the prepared electrode enables the electrolyte utilization and energy efficiency to be 73.9% and 77.4% at a high current density of 300 mA cm-2, which are correspondingly 43.3% and 15.4% higher than that of battery assembled with a pristine electrode. More impressively, the present battery exhibits good stability and high capacity retention during the cycle test. The superior performance is ascribed to the significant improvement in the electrochemical kinetics and enlarged active sites toward V3+/V2+ redox reaction.

Preparation and screening of crystalline zeolite and hydrothermally-synthesized materials

DOEpatents

Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy; Briceno, Gabriel; Sun, Xiao-Dong; Wang, Kai-An

2005-03-08

Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

Electrodeposition of Rhodium Nanowires Arrays and Their Morphology-Dependent Hydrogen Evolution Activity

PubMed Central

Zhang, Liqiu; Liu, Lichun; Wang, Hongdan; Shen, Hongxia; Cheng, Qiong; Yan, Chao; Park, Sungho

2017-01-01

This work reports on the electrodeposition of rhodium (Rh) nanowires with a controlled surface morphology synthesized using an anodic aluminum oxide (AAO) template. Vertically aligned Rh nanowires with a smooth and coarse morphology were successfully deposited by adjusting the electrode potential and the concentration of precursor ions and by involving a complexing reagent in the electrolyte solution. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were used to follow the morphological evolution of Rh nanowires. As a heterogeneous electrocatalyst for hydrogen evolution reactions (HER), the coarse Rh nanowire array exhibited an enhanced catalytic performance respect to smooth ones due to the larger surface area to mass ratio and the higher density of catalytically active defects, as evidenced by voltammetric measurements and TEM. Results suggest that the morphology of metallic nanomaterials could be readily engineered by electrodeposition. The controlled electrodeposition offers great potential for the development of an effective synthesis tool for heterogeneous catalysts with a superior performance for wide applications. PMID:28467375

Ultraviolet detection using TiO2 nanowire array with Ag Schottky contact

NASA Astrophysics Data System (ADS)

Chinnamuthu, P.; Dhar, J. C.; Mondal, A.; Bhattacharyya, A.; Singh, N. K.

2012-04-01

The glancing angle deposition technique has been employed to synthesize TiO2 nanowire (NW) arrays which have been characterized by x-ray diffraction, field emission-scanning electron microscopy and high resolution transmission electron microscopy. Optical absorption measurements show the absorption edge at 3.42 eV and 3.48 eV for TiO2 thin film (TF) and NW, respectively. The blue shift in absorption band is attributed to quantum confinement in NW structures. Photoluminescence measurement revealed oxygen-defect-related emission at 425 nm (˜2.9 eV). Ag/TiO2 (NW) and Ag/TiO2 (TF) contacts exhibit Schottky behaviour, and a higher turn-on voltage (˜6.5 V) was observed for NW devices than that of TF devices (˜5.25 V) under dark condition. In addition, TiO2-NW-based devices show twofold improvement in photodetection efficiency in the UV region, compared with TiO2-TF-based devices.

Separation and reconstruction of high pressure water-jet reflective sound signal based on ICA

NASA Astrophysics Data System (ADS)

Yang, Hongtao; Sun, Yuling; Li, Meng; Zhang, Dongsu; Wu, Tianfeng

2011-12-01

The impact of high pressure water-jet on the different materials target will produce different reflective mixed sound. In order to reconstruct the reflective sound signals distribution on the linear detecting line accurately and to separate the environment noise effectively, the mixed sound signals acquired by linear mike array were processed by ICA. The basic principle of ICA and algorithm of FASTICA were described in detail. The emulation experiment was designed. The environment noise signal was simulated by using band-limited white noise and the reflective sound signal was simulated by using pulse signal. The reflective sound signal attenuation produced by the different distance transmission was simulated by weighting the sound signal with different contingencies. The mixed sound signals acquired by linear mike array were synthesized by using the above simulated signals and were whitened and separated by ICA. The final results verified that the environment noise separation and the reconstruction of the detecting-line sound distribution can be realized effectively.

Large-area, flexible imaging arrays constructed by light-charge organic memories

PubMed Central

Zhang, Lei; Wu, Ti; Guo, Yunlong; Zhao, Yan; Sun, Xiangnan; Wen, Yugeng; Yu, Gui; Liu, Yunqi

2013-01-01

Existing organic imaging circuits, which offer attractive benefits of light weight, low cost and flexibility, are exclusively based on phototransistor or photodiode arrays. One shortcoming of these photo-sensors is that the light signal should keep invariant throughout the whole pixel-addressing and reading process. As a feasible solution, we synthesized a new charge storage molecule and embedded it into a device, which we call light-charge organic memory (LCOM). In LCOM, the functionalities of photo-sensor and non-volatile memory are integrated. Thanks to the deliberate engineering of electronic structure and self-organization process at the interface, 92% of the stored charges, which are linearly controlled by the quantity of light, retain after 20000 s. The stored charges can also be non-destructively read and erased by a simple voltage program. These results pave the way to large-area, flexible imaging circuits and demonstrate a bright future of small molecular materials in non-volatile memory. PMID:23326636

Magnetic field directed assembly of superstructures of ferrite-ferroelectric core-shell nanoparticles and studies on magneto-electric interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srinivasan, G., E-mail: srinivas@oakland.edu; Sreenivasulu, G.; Benoit, Crystal

2015-05-07

Composites of ferromagnetic and ferroelectric are of interest for studies on mechanical strain mediated magneto-electric (ME) interactions and for useful technologies. Here, we report on magnetic-field-assisted-assembly of barium titanate (BTO)-nickel ferrite (NFO) core-shell particles into linear chains and 2D/3D arrays and measurements of ME effects in such assemblies. First, we synthesized the core-shell nano-particles with 50–600 nm BTO and 10–200 nm NFO by chemical self-assembly by coating the ferroic particles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst via the “click” reaction. The core-shell structure was confirmed with electron microscopy and scanning probe microscopy. Wemore » obtained superstructure of the core-shell particles by subjecting them to a magnetic field gradient that exerts an attractive force on the particles and align them toward the regions of high field strengths. At low particle concentration, linear chains were formed and they evolved into 2D and 3D arrays at high particle concentrations. Magnetoelectric characterization on unassembled films and assembled arrays has been performed through measurements of low-frequency ME voltage coefficient (MEVC) by subjecting the sample to a bias magnetic field and an ac magnetic field. The MEVC is higher for field-assembled samples than for unassembled films and is found to be sensitive to field orientation with a higher MEVC for magnetic fields parallel to the array direction than for magnetic fields perpendicular to the array. A maximum MEVC of 20 mV/cm Oe, one of the highest reported for any bulk nanocomposite, is measured across the array thickness. A model is provided for ME coupling in the superstructures of BTO-NFO particulate composites. First, we estimated the MEVC for a free-standing BTO-NFO core-shell particle and then extended the model to include an array of linear chains of the particles. The theoretical estimates are in qualitative agreement with the data.« less

Magnetic field directed assembly of superstructures of ferrite-ferroelectric core-shell nanoparticles and studies on magneto-electric interactions

NASA Astrophysics Data System (ADS)

Srinivasan, G.; Sreenivasulu, G.; Benoit, Crystal; Petrov, V. M.; Chavez, F.

2015-05-01

Composites of ferromagnetic and ferroelectric are of interest for studies on mechanical strain mediated magneto-electric (ME) interactions and for useful technologies. Here, we report on magnetic-field-assisted-assembly of barium titanate (BTO)-nickel ferrite (NFO) core-shell particles into linear chains and 2D/3D arrays and measurements of ME effects in such assemblies. First, we synthesized the core-shell nano-particles with 50-600 nm BTO and 10-200 nm NFO by chemical self-assembly by coating the ferroic particles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst via the "click" reaction. The core-shell structure was confirmed with electron microscopy and scanning probe microscopy. We obtained superstructure of the core-shell particles by subjecting them to a magnetic field gradient that exerts an attractive force on the particles and align them toward the regions of high field strengths. At low particle concentration, linear chains were formed and they evolved into 2D and 3D arrays at high particle concentrations. Magnetoelectric characterization on unassembled films and assembled arrays has been performed through measurements of low-frequency ME voltage coefficient (MEVC) by subjecting the sample to a bias magnetic field and an ac magnetic field. The MEVC is higher for field-assembled samples than for unassembled films and is found to be sensitive to field orientation with a higher MEVC for magnetic fields parallel to the array direction than for magnetic fields perpendicular to the array. A maximum MEVC of 20 mV/cm Oe, one of the highest reported for any bulk nanocomposite, is measured across the array thickness. A model is provided for ME coupling in the superstructures of BTO-NFO particulate composites. First, we estimated the MEVC for a free-standing BTO-NFO core-shell particle and then extended the model to include an array of linear chains of the particles. The theoretical estimates are in qualitative agreement with the data.

Programming Recognition Arrays through Double Chalcogen-Bonding Interactions.

PubMed

Biot, Nicolas; Bonifazi, Davide

2018-04-11

In this work, we have programmed and synthesized a recognition motif constructed around a chalcogenazolo-pyridine scaffold (CGP) that, through the formation of frontal double chalcogen-bonding interactions, associates into dimeric EX-type complexes. The reliability of the double chalcogen-bonding interaction has been shown at the solid-state by X-ray analysis, depicting the strongest recognition persistence for a Te-congener. The high recognition fidelity, chemical and thermal stability and easy derivatization at the 2-position makes CGP a convenient motif for constructing supramolecular architectures through programmed chalcogen-bonding interactions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Proceedings of the Antenna Applications Symposium Held in Hanscom AFB, Massachusetts on 23-25 September 1987. Volume 2

DTIC Science & Technology

1988-07-01

iv BROADBAND ANTENNAS Contents 21. "Performance Characteristics of Notch Array Elements Over a 6/1 263 Frequoncy Band," C. J. Monser * 22. " Broadband ...synthesized RF signal is taken from the output port of the Hewlett-Packard 8408B Microvae Network Alnalyzer to a 20-watt TWT anplifier, and then to...j kr -Sinn H 0 = -jk 47rjk ° a 2 H r4 0 r 406 4. Helix antenna The cur-ent distribution of a helix antenna as shown in Fig. 2.11 of [33 may be

Shot noise limits to sensitivity of optical interferometry

NASA Technical Reports Server (NTRS)

Prasad, Sudhakar

1992-01-01

By arguing that the limiting noise is the photoelectron shot noise, we show that the sensitivity of image synthesis by an ideal optical interferometer is independent of the details of beam-splitting and recombination. The signal-to-noise ratio of the synthesized image is proportional to the square root of the total number of photoelectrons detected by the entire array. For non-ideal interferometers, which are forced to employ a closure-phase method of indirect inference of the visibility data, essentially the same result holds for strong sources, but at weak light levels beam-splitting degrades sensitivity.

An Optimized Configuration for the Brazilian Decimetric Array

NASA Astrophysics Data System (ADS)

Sawant, Hanumant; Faria, Claudio; Stephany, Stephan

The Brazilian Decimetric Array (BDA) is a radio interferometer designed to operate in the frequency range of 1.2-1.7, 2.8 and 5.6 GHz and to obtain images of radio sources with high dynamic range. A 5-antenna configuration is already operational being implemented in BDA phase I. Phase II will provide a 26-antenna configuration forming a compact T-array, whereas phase III will include further 12 antennas. However, the BDA site has topographic constraints that preclude the placement of these antennas along the lines defined by the 3 arms of the T-array. Therefore, some antennas must be displaced in a direction that is slightly transverse tothese lines. This work presents the investigation of possible optimized configurations for all 38 antennas spread over the distances of 2.5 x 1.25 km. It was required to determine the optimal position of the last 12 antennas.A new optimization strategy was then proposed in order to obtain the optimal array configuration. It is based on the entropy of the distribution of the sampled points in the Fourier plane. A stochastic model, Ant Colony Optimization, uses the entropy of the such distribution to iteratively refine the candidate solutions. The proposed strategy can be used to determine antenna locations for free-shape arrays in order to provide uniform u-v coverage with minimum redundancy of sampled points in u-v plane that are less susceptible to errors due to unmeasured Fourier components. A different distribution could be chosen for the coverage. It also allows to consider the topographical constraints of the available site. Furthermore, it provides an optimal configuration even considering the predetermined placement of the 26 antennas that compose the central T-array. In this case, the optimal location of the last 12 antennas was determined. Performance results corresponding to the Fourier plane coverage, synthesized beam and sidelobes levels are shown for this optimized BDA configuration and are compared to the results of the standard T-array configuration that cannot be implemented due to site constraints. —————————————————————————————-

Variable deflection response of sensitive CNT-on-fiber artificial hair sensors from CNT synthesis in high aspect ratio microcavities

NASA Astrophysics Data System (ADS)

Slinker, Keith; Maschmann, Matthew R.; Kondash, Corey; Severin, Benjamin; Phillips, David; Dickinson, Benjamin T.; Reich, Gregory; Baur, Jeff

2015-03-01

Crickets, locusts, bats, and many other animals detect changes in their environment with distributed arrays of flow-sensitive hairs. Here we discuss the fabrication and characterization of a relatively new class of pore-based, artificial hair sensors that take advantage of the mechanical properties of structural microfibers and the electromechanical properties of self-aligned carbon nanotube arrays to rapidly transduce changes in low speed air flow. The radially aligned nanotubes are able to be synthesized along the length of the fibers inside the high aspect ratio cavity between the fiber surface and the wall of a microcapillary pore. The growth self-positions the fibers within the capillary and forms a conductive path between detection electrodes. As the hair is deflected, nanotubes are compressed to produce a typical resistance change of 1-5% per m/s of air speed which we believe are the highest sensitivities reported for air velocities less than 10 m/s. The quasi-static response of the sensors to point loads is compared to that from the distributed loads of air flow. A plane wave tube is used to measure their dynamic response when perturbed at acoustic frequencies. Correlation of the nanotube height profile inside the capillary to a diffusion transport model suggests that the nanotube arrays can be controllably tapered along the fiber. Like their biological counterparts, many applications can be envisioned for artificial hair sensors by tailoring their individual response and incorporating them into arrays for detecting spatio-temporal flow patterns over rigid surfaces such as aircraft.

Creating new superconducting & semiconducting nanomaterials and investigating the effect of reduced dimensionality on their properties

NASA Astrophysics Data System (ADS)

Mishra, Sukhada

The field of nanomaterials has continued to attract researchers to understand the fundamentals and to investigate potential applications in the fields of semiconductor physics, microfabrication, nanomedicine, surface sciences etc. One of the most critical aspects of the nanomaterials research is to establish synthetic protocols, which can address the underlying product requirements of reproducibility, homogenous morphology and controlled elemental composition. We have focused our research in exploring synthetic routes for the synthesis of superconducting and semiconducting nanomaterials and analyze their structure---property relationship through detailed characterizations. The first part of dissertation is focused on the synthesis of superconducting FeSe nanostructures using catalyst assisted chemical vapor deposition (CVD) technique. The effect of catalyst---FeSe interphase on the d spacing of the FeSe nanostructures has been analyzed, and the internal pressure effect on the Tc has been investigated further through in depth characterizations. The emphasis of second part is on the development of a simple yet versatile protocol for the synthesis of vertically aligned nanorod arrays on conducting substrate by combining electron beam lithography technique with electrochemical deposition. The technique has been utilized to fabricate photovoltaic CdTe nanorod arrays on conducting substrate and further extended to devise CdS---CdTe nanorod arrays to create radial and lateral p---n junction assembly. Using photo---electrochemical analysis, it was observed that, the nanorod arrays yielded higher photo---electrochemical current compared to the thin film counterpart. The third part of dissertation describes the CVD protocol to synthesize multifunctional, dumbbell shaped Au---CoSe nanoparticles, which possess potential applications in ' theronostic' biological examinations.

Astronomical Verification of a Stabilized Frequency Reference Transfer System for the Square Kilometer Array

NASA Astrophysics Data System (ADS)

Gozzard, David R.; Schediwy, Sascha W.; Dodson, Richard; Rioja, María J.; Hill, Mike; Lennon, Brett; McFee, Jock; Mirtschin, Peter; Stevens, Jamie; Grainge, Keith

2017-07-01

In order to meet its cutting-edge scientific objectives, the Square Kilometre Array (SKA) telescope requires high-precision frequency references to be distributed to each of its antennas. The frequency references are distributed via fiber-optic links and must be actively stabilized to compensate for phase noise imposed on the signals by environmental perturbations on the links. SKA engineering requirements demand that any proposed frequency reference distribution system be proved in “astronomical verification” tests. We present results of the astronomical verification of a stabilized frequency reference transfer system proposed for SKA-mid. The dual-receiver architecture of the Australia Telescope Compact Array was exploited to subtract the phase noise of the sky signal from the data, allowing the phase noise of observations performed using a standard frequency reference, as well as the stabilized frequency reference transfer system transmitting over 77 km of fiber-optic cable, to be directly compared. Results are presented for the fractional frequency stability and phase drift of the stabilized frequency reference transfer system for celestial calibrator observations at 5 and 25 GHz. These observations plus additional laboratory results for the transferred signal stability over a 166 km metropolitan fiber-optic link are used to show that the stabilized transfer system under test exceeds all SKA phase-stability requirements within a broad range of observing conditions. Furthermore, we have shown that alternative reference dissemination systems that use multiple synthesizers to supply reference signals to sub-sections of an array may limit the imaging capability of the telescope.

Extraction of 3D Information from Circular Array Measurements for Auralization with Wave Field Synthesis

NASA Astrophysics Data System (ADS)

de Vries, Diemer; Hörchens, Lars; Grond, Peter

2007-12-01

The state of the art of wave field synthesis (WFS) systems is that they can reproduce sound sources and secondary (mirror image) sources with natural spaciousness in a horizontal plane, and thus perform satisfactory 2D auralization of an enclosed space, based on multitrace impulse response data measured or simulated along a 2D microphone array. However, waves propagating with a nonzero elevation angle are also reproduced in the horizontal plane, which is neither physically nor perceptually correct. In most listening environments to be auralized, the floor is highly absorptive since it is covered with upholstered seats, occupied during performances by a well-dressed audience. A first-order ceiling reflection, reaching the floor directly or via a wall, will be severely damped and will not play a significant role in the room response anymore. This means that a spatially correct WFS reproduction of first-order ceiling reflections, by means of a loudspeaker array at the ceiling of the auralization reproduction room, is necessary and probably sufficient to create the desired 3D spatial perception. To determine the driving signals for the loudspeakers in the ceiling array, it is necessary to identify the relevant ceiling reflection(s) in the multichannel impulse response data and separate those events from the data set. Two methods are examined to identify, separate, and reproduce the relevant reflections: application of the Radon transform, and decomposition of the data into cylindrical harmonics. Application to synthesized and measured data shows that both methods in principle are able to identify, separate, and reproduce the relevant events.

Highly flexible, all solid-state micro-supercapacitors from vertically aligned carbon nanotubes.

PubMed

Hsia, Ben; Marschewski, Julian; Wang, Shuang; In, Jung Bin; Carraro, Carlo; Poulikakos, Dimos; Grigoropoulos, Costas P; Maboudian, Roya

2014-02-07

We report a highly flexible planar micro-supercapacitor with interdigitated finger electrodes of vertically aligned carbon nanotubes (VACNTs). The planar electrode structures are patterned on a thin polycarbonate substrate with a facile, maskless laser-assisted dry transfer method. Sputtered Ni is used to reduce the in-plane resistance of the VACNT electrodes. An ionogel, an ionic liquid in a semi-solid matrix, is used as an electrolyte to form a fully solid-state device. We measure a specific capacitance of 430 μF cm(-2) for a scan rate of 0.1 V s(-1) and achieve rectangular cyclic voltammograms at high scan rates of up to 100 V s(-1). Minimal change in capacitance is observed under bending. Mechanical fatigue tests with more than 1000 cycles confirm the high flexibility and durability of the novel material combination chosen for this device. Our results indicate that this scalable and facile fabrication technique shows promise for application in integrated energy storage for all solid-state flexible microdevices.

Fabrication of diamond based sensors for use in extreme environments

DOE PAGES

Samudrala, Gopi K.; Moore, Samuel L.; Vohra, Yogesh K.

2015-04-23

Electrical and magnetic sensors can be lithographically fabricated on top of diamond substrates and encapsulated in a protective layer of chemical vapor deposited single crystalline diamond. This process when carried out on single crystal diamond anvils employed in high pressure research is termed as designer diamond anvil fabrication. These designer diamond anvils allow researchers to study electrical and magnetic properties of materials under extreme conditions without any possibility of damaging the sensing elements. We describe a novel method for the fabrication of designer diamond anvils with the use of maskless lithography and chemical vapor deposition in this paper. This methodmore » can be utilized to produce diamond based sensors which can function in extreme environments of high pressures, high and low temperatures, corrosive and high radiation conditions. Here, we demonstrate applicability of these diamonds under extreme environments by performing electrical resistance measurements during superconducting transition in rare earth doped iron-based compounds under high pressures to 12 GPa and low temperatures to 10 K.« less

Fabrication of diamond based sensors for use in extreme environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samudrala, Gopi K.; Moore, Samuel L.; Vohra, Yogesh K.

Electrical and magnetic sensors can be lithographically fabricated on top of diamond substrates and encapsulated in a protective layer of chemical vapor deposited single crystalline diamond. This process when carried out on single crystal diamond anvils employed in high pressure research is termed as designer diamond anvil fabrication. These designer diamond anvils allow researchers to study electrical and magnetic properties of materials under extreme conditions without any possibility of damaging the sensing elements. We describe a novel method for the fabrication of designer diamond anvils with the use of maskless lithography and chemical vapor deposition in this paper. This methodmore » can be utilized to produce diamond based sensors which can function in extreme environments of high pressures, high and low temperatures, corrosive and high radiation conditions. Here, we demonstrate applicability of these diamonds under extreme environments by performing electrical resistance measurements during superconducting transition in rare earth doped iron-based compounds under high pressures to 12 GPa and low temperatures to 10 K.« less

Highly Stable Nanolattice Structures using Nonlinear Laser Lithography

NASA Astrophysics Data System (ADS)

Yavuz, Ozgun; Tokel, Onur; Ergecen, Emre; Pavlov, Ihor; Makey, Ghaith; Ilday, Fatih Omer

Periodic nanopatterning is crucial for multiple technologies, including photovoltaics and display technologies. Conventional optical lithography techniques require complex masks, while e-beam and ion-beam lithography require expensive equipment. With the Nonlinear Laser Lithography (NLL) technique, we had recently shown that various surfaces can be covered with extremely periodic nanopatterns with ultrafast lasers through a single-step, maskless and inexpensive method. Here, we expand NLL nanopatterns to flexible materials, and also present a fully predictive model for the formation of NLL nanostructures as confirmed with experiments. In NLL, a nonlocal positive feedback mechanism (dipole scattering) competes with a rate limiting negative feedback mechanism. Here, we show that judicious use of the laser polarisation can constrain the lattice symmetry, while the nonlinearities regulate periodicity. We experimentally demonstrate that in addition to one dimensional periodic stripes, two dimensional lattices can be produced on surfaces. In particular, hexagonal and square lattices were produced, which are highly desired for display technologies. Notably, with this approach, we can tile flexible substrates, which can find applications in next generation display technologies.

New frontiers of atomic layer etching

NASA Astrophysics Data System (ADS)

Sherpa, Sonam D.; Ranjan, Alok

2018-03-01

Interest in atomic layer etching (ALE) has surged recently because it offers several advantages over continuous or quasicontinuous plasma etching. These benefits include (1) independent control of ion energy, ion flux, and radical flux, (2) flux-independent etch rate that mitigates the iso-dense loading effects, and (3) ability to control the etch rate with atomic or nanoscale precision. In addition to these benefits, we demonstrate an area-selective etching for maskless lithography as a new frontier of ALE. In this paper, area-selective etching refers to the confinement of etching into the specific areas of the substrate. The concept of area-selective etching originated during our studies on quasi-ALE of silicon nitride which consists of sequential exposure of silicon nitride to hydrogen and fluorinated plasma. The findings of our studies reported in this paper suggest that it may be possible to confine the etching into specific areas of silicon nitride without using any mask by replacing conventional hydrogen plasma with a localized source of hydrogen ions.

Genome-wide transcriptional analysis of flagellar regeneration in Chlamydomonas reinhardtii identifies orthologs of ciliary disease genes

NASA Technical Reports Server (NTRS)

Stolc, Viktor; Samanta, Manoj Pratim; Tongprasit, Waraporn; Marshall, Wallace F.

2005-01-01

The important role that cilia and flagella play in human disease creates an urgent need to identify genes involved in ciliary assembly and function. The strong and specific induction of flagellar-coding genes during flagellar regeneration in Chlamydomonas reinhardtii suggests that transcriptional profiling of such cells would reveal new flagella-related genes. We have conducted a genome-wide analysis of RNA transcript levels during flagellar regeneration in Chlamydomonas by using maskless photolithography method-produced DNA oligonucleotide microarrays with unique probe sequences for all exons of the 19,803 predicted genes. This analysis represents previously uncharacterized whole-genome transcriptional activity profiling study in this important model organism. Analysis of strongly induced genes reveals a large set of known flagellar components and also identifies a number of important disease-related proteins as being involved with cilia and flagella, including the zebrafish polycystic kidney genes Qilin, Reptin, and Pontin, as well as the testis-expressed tubby-like protein TULP2.

Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

PubMed Central

Schröder, Tim; Trusheim, Matthew E.; Walsh, Michael; Li, Luozhou; Zheng, Jiabao; Schukraft, Marco; Sipahigil, Alp; Evans, Ruffin E.; Sukachev, Denis D.; Nguyen, Christian T.; Pacheco, Jose L.; Camacho, Ryan M.; Bielejec, Edward S.; Lukin, Mikhail D.; Englund, Dirk

2017-01-01

The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ∼32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ∼2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ∼51 GHz and close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ∼1.4 times the natural linewidth. This method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors. PMID:28548097

Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

DOE PAGES

Schroder, Tim; Trusheim, Matthew E.; Walsh, Michael; ...

2017-05-26

The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ~32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ~2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ~51 GHz andmore » close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ~1.4 times the natural linewidth. Furthermore, this method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.« less

Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroder, Tim; Trusheim, Matthew E.; Walsh, Michael

The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ~32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ~2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ~51 GHz andmore » close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ~1.4 times the natural linewidth. Furthermore, this method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.« less

Vacuum-free, maskless patterning of Ni electrodes by laser reductive sintering of NiO nanoparticle ink and its application to transparent conductors.

PubMed

Lee, Daeho; Paeng, Dongwoo; Park, Hee K; Grigoropoulos, Costas P

2014-10-28

We introduce a method for direct patterning of Ni electrodes through selective laser direct writing (LDW) of NiO nanoparticle (NP) ink. High-resolution Ni patterns are generated from NiO NP thin films by a vacuum-free, lithography-free, and solution-processable route. In particular, a continuous wave laser is used for the LDW reductive sintering of the metal oxide under ambient conditions with the aid of reducing agents in the ink solvent. Thin (∼ 40 nm) Ni electrodes of glossy metallic surfaces with smooth morphology and excellent edge definition can be fabricated. By applying this method, we demonstrate a high transmittance (>87%), electrically conducting panel for a touch screen panel application. The resistivity of the Ni electrode is less than an order of magnitude higher compared to that of the bulk Ni. Mechanical bending test, tape-pull test, and ultrasonic bath test confirm the robust adhesion of the electrodes on glass and polymer substrates.

Additive manufacturing of hybrid circuits

DOE PAGES

Bell, Nelson S.; Sarobol, Pylin; Cook, Adam; ...

2016-03-26

There is a rising interest in developing functional electronics using additively manufactured components. Considerations in materials selection and pathways to forming hybrid circuits and devices must demonstrate useful electronic function; must enable integration; and must complement the complex shape, low cost, high volume, and high functionality of structural but generally electronically passive additively manufactured components. This article reviews several emerging technologies being used in industry and research/development to provide integration advantages of fabricating multilayer hybrid circuits or devices. First, we review a maskless, noncontact, direct write (DW) technology that excels in the deposition of metallic colloid inks for electrical interconnects.more » Second, we review a complementary technology, aerosol deposition (AD), which excels in the deposition of metallic and ceramic powder as consolidated, thick conformal coatings and is additionally patternable through masking. As a result, we show examples of hybrid circuits/devices integrated beyond 2-D planes, using combinations of DW or AD processes and conventional, established processes.« less

Nano-textured high sensitivity ion sensitive field effect transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hajmirzaheydarali, M.; Sadeghipari, M.; Akbari, M.

2016-02-07

Nano-textured gate engineered ion sensitive field effect transistors (ISFETs), suitable for high sensitivity pH sensors, have been realized. Utilizing a mask-less deep reactive ion etching results in ultra-fine poly-Si features on the gate of ISFET devices where spacing of the order of 10 nm and less is achieved. Incorporation of these nano-sized features on the gate is responsible for high sensitivities up to 400 mV/pH in contrast to conventional planar structures. The fabrication process for this transistor is inexpensive, and it is fully compatible with standard complementary metal oxide semiconductor fabrication procedure. A theoretical modeling has also been presented to predict themore » extension of the diffuse layer into the electrolyte solution for highly featured structures and to correlate this extension with the high sensitivity of the device. The observed ultra-fine features by means of scanning electron microscopy and transmission electron microscopy tools corroborate the theoretical prediction.« less

Maskless deposition technique for the physical vapor deposition of thin film and multilayer coatings with subnanometer precision and accuracy

DOEpatents

Vernon, Stephen P.; Ceglio, Natale M.

2000-01-01

The invention is a method for the production of axially symmetric, graded and ungraded thickness thin film and multilayer coatings that avoids the use of apertures or masks to tailor the deposition profile. A motional averaging scheme permits the deposition of uniform thickness coatings independent of the substrate radius. Coating uniformity results from an exact cancellation of substrate radius dependent terms, which occurs when the substrate moves at constant velocity. If the substrate is allowed to accelerate over the source, arbitrary coating profiles can be generated through appropriate selection and control of the substrate center of mass equation of motion. The radial symmetry of the coating profile is an artifact produced by orbiting the substrate about its center of mass; other distributions are obtained by selecting another rotation axis. Consequently there is a direct mapping between the coating thickness and substrate equation of motion which can be used to tailor the coating profile without the use of masks and apertures.

Wafer-scale self-organized InP nanopillars with controlled orientation for photovoltaic devices.

PubMed

Sanatinia, Reza; Berrier, Audrey; Dhaka, Veer; Perros, Alexander P; Huhtio, Teppo; Lipsanen, Harri; Anand, Srinivasan

2015-10-16

A unique wafer-scale self-organization process for generation of InP nanopillars is demonstrated, which is based on maskless ion-beam etching (IBE) of InP developed to obtain the nanopillars, where the height, shape, and orientation of the nanopillars can be varied by controlling the processing parameters. The fabricated InP nanopillars exhibit broadband suppression of the reflectance, 'black InP,' a property useful for solar cells. The realization of a conformal p-n junction for carrier collection, in the fabricated solar cells, is achieved by a metalorganic vapor phase epitaxy (MOVPE) overgrowth step on the fabricated pillars. The conformal overgrowth retains the broadband anti-reflection property of the InP nanopillars, indicating the feasibility of this technology for solar cells. Surface passivation of the formed InP nanopillars using sulfur-oleylamine solution resulted in improved solar-cell characteristics. An open-circuit voltage of 0.71 V and an increase of 0.13 V compared to the unpassivated device were achieved.

Self-supported Zn3P2 nanowire arrays grafted on carbon fabrics as an advanced integrated anode for flexible lithium ion batteries

NASA Astrophysics Data System (ADS)

Li, Wenwu; Gan, Lin; Guo, Kai; Ke, Linbo; Wei, Yaqing; Li, Huiqiao; Shen, Guozhen; Zhai, Tianyou

2016-04-01

We, for the first time, successfully grafted well-aligned binary lithium-reactive zinc phosphide (Zn3P2) nanowire arrays on carbon fabric cloth by a facile CVD method. When applied as a novel self-supported binder-free anode for lithium ion batteries (LIBs), the hierarchical three-dimensional (3D) integrated anode shows excellent electrochemical performances: a highly reversible initial lithium storage capacity of ca. 1200 mA h g-1 with a coulombic efficiency of up to 88%, a long lifespan of over 200 cycles without obvious decay, and a high rate capability of ca. 400 mA h g-1 capacity retention at an ultrahigh rate of 15 A g-1. More interestingly, a flexible LIB full cell is assembled based on the as-synthesized integrated anode and the commercial LiFePO4 cathode, and shows striking lithium storage performances very close to the half cells: a large reversible capacity over 1000 mA h g-1, a long cycle life of over 200 cycles without obvious decay, and an ultrahigh rate performance of ca. 300 mA h g-1 even at 20 A g-1. Considering the excellent lithium storage performances of coin-type half cells as well as flexible full cells, the as-prepared carbon cloth grafted well-aligned Zn3P2 nanowire arrays would be a promising integrated anode for flexible LIB full cell devices.We, for the first time, successfully grafted well-aligned binary lithium-reactive zinc phosphide (Zn3P2) nanowire arrays on carbon fabric cloth by a facile CVD method. When applied as a novel self-supported binder-free anode for lithium ion batteries (LIBs), the hierarchical three-dimensional (3D) integrated anode shows excellent electrochemical performances: a highly reversible initial lithium storage capacity of ca. 1200 mA h g-1 with a coulombic efficiency of up to 88%, a long lifespan of over 200 cycles without obvious decay, and a high rate capability of ca. 400 mA h g-1 capacity retention at an ultrahigh rate of 15 A g-1. More interestingly, a flexible LIB full cell is assembled based on the as-synthesized integrated anode and the commercial LiFePO4 cathode, and shows striking lithium storage performances very close to the half cells: a large reversible capacity over 1000 mA h g-1, a long cycle life of over 200 cycles without obvious decay, and an ultrahigh rate performance of ca. 300 mA h g-1 even at 20 A g-1. Considering the excellent lithium storage performances of coin-type half cells as well as flexible full cells, the as-prepared carbon cloth grafted well-aligned Zn3P2 nanowire arrays would be a promising integrated anode for flexible LIB full cell devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08467a

The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers

DOE PAGES

Olek, Anna T.; Rayon, Catherine; Makowski, Lee; ...

2014-07-10

Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice ( Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain,more » elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. As a result, the arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.« less

Fabrication and magnetic properties of Fe nanostructures in anodic alumina membrane

NASA Astrophysics Data System (ADS)

Lim, J.-H.; Chae, W.-S.; Lee, H.-O.; Malkinski, L.; Min, S.-G.; Wiley, J. B.; Jun, J.-H.; Lee, S.-H.; Jung, J.-S.

2010-05-01

Several Fe nanostructures with different lengths, diameters, and separations of the constituting magnetic components have been synthesized using anodized alumina membranes (AAMs) to understand the influence of these parameters on their magnetic properties. Fe nanostructures with high crystallinity and (110) orientation were synthesized by electrodeposition at room temperature in regular AAMs and mild-hard AAM (Mi-Ha AAM). Fe nanostructures with different aspect ratios (1:1, 1:10, and 1:75) in the form of nanodots, nanorods, or nanowires were synthesized in regular AAMs with the 100 nm interpore distance. Mi-Ha AAMs with two different pore sizes (70 and 120 nm) and 250 nm interpore distances were used to investigate the effect of the interactions and of the diameter of the wires on their magnetic behavior. Nearly linear magnetization characteristics with small coercivity, observed for Fe nanowires, suggest the magnetization rotation to be the predominant magnetization process for the field applied transverse to the wires. The anisotropy of the arrays was governed by the shape anisotropy of the magnetic objects with different aspect ratios. Reduced interactions between the nanowires grown in Mi-Ha AAMs resulted in enhancement of the average anisotropy. It is believed that due to difference in spin configuration, the increased diameter of the nanowires led to reduction in the coercivity in the case of the field applied along the wires.

The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers.

PubMed

Olek, Anna T; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; Himmel, Michael E; Bolin, Jeffrey T; Carpita, Nicholas C

2014-07-01

Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. The arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize. © 2014 American Society of Plant Biologists. All rights reserved.

Growth control of carbon nanotubes using by anodic aluminum oxide nano templates.

PubMed

Park, Yong Seob; Choi, Won Seek; Yi, Junsin; Lee, Jaehyeong

2014-05-01

Anodic Aluminum Oxide (AAO) template prepared in acid electrolyte possess regular and highly anisotropic porous structure with pore diameter range from five to several hundred nanometers, and with a density of pores ranging from 10(9) to 10(11) cm(-2). AAO can be used as microfilters and templates for the growth of CNTs and metal or semiconductor nanowires. Varying anodizing conditions such as temperature, electrolyte, applied voltage, anodizing and widening time, one can control the diameter, the length, and the density of pores. In this work, we deposited Al thin film by radio frequency magnetron sputtering method to fabricate AAO nano template and synthesized multi-well carbon nanotubes on a glass substrate by microwave plasma-enhanced chemical vapor deposition (MPECVD). AAO nano-porous templates with various pore sizes and depths were introduced to control the dimension and density of CNT arrays. The AAO nano template was synthesize on glass by two-step anodization technique. The average diameter and interpore distance of AAO nano template are about 65 nm and 82 nm. The pore density and AAO nano template thickness are about 2.1 x 10(10) pores/cm2 and 1 microm, respectively. Aligned CNTs on the AAO nano template were synthesized by MPECVD at 650 degrees C with the Ni catalyst layer. The length and diameter of CNTs were grown 2 microm and 50 nm, respectively.

Reproducible, high-throughput synthesis of colloidal nanocrystals for optimization in multidimensional parameter space.

PubMed

Chan, Emory M; Xu, Chenxu; Mao, Alvin W; Han, Gang; Owen, Jonathan S; Cohen, Bruce E; Milliron, Delia J

2010-05-12

While colloidal nanocrystals hold tremendous potential for both enhancing fundamental understanding of materials scaling and enabling advanced technologies, progress in both realms can be inhibited by the limited reproducibility of traditional synthetic methods and by the difficulty of optimizing syntheses over a large number of synthetic parameters. Here, we describe an automated platform for the reproducible synthesis of colloidal nanocrystals and for the high-throughput optimization of physical properties relevant to emerging applications of nanomaterials. This robotic platform enables precise control over reaction conditions while performing workflows analogous to those of traditional flask syntheses. We demonstrate control over the size, size distribution, kinetics, and concentration of reactions by synthesizing CdSe nanocrystals with 0.2% coefficient of variation in the mean diameters across an array of batch reactors and over multiple runs. Leveraging this precise control along with high-throughput optical and diffraction characterization, we effectively map multidimensional parameter space to tune the size and polydispersity of CdSe nanocrystals, to maximize the photoluminescence efficiency of CdTe nanocrystals, and to control the crystal phase and maximize the upconverted luminescence of lanthanide-doped NaYF(4) nanocrystals. On the basis of these demonstrative examples, we conclude that this automated synthesis approach will be of great utility for the development of diverse colloidal nanomaterials for electronic assemblies, luminescent biological labels, electroluminescent devices, and other emerging applications.

A high performance DAC /DDS daughter module for the RHIC LLRF platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, T.; Harvey, M.; Narayan, G.

The RHIC LLRF upgrade is a flexible, modular system. Output signals are generated by a custom designed XMC card with 4 high speed digital to analog (DAC) converters interfaced to a high performance field programmable gate array (FPGA). This paper discusses the hardware details of the XMC DAC board as well as the implementation of a low noise rf synthesizer with digital IQ modulation. This synthesizer also provides injection phase cogging and frequency hop rebucketing capabilities. A new modular RHIC LLRF system was recently designed and commissioned based on custom designed XMC cards. As part of that effort a highmore » speed, four channel DAC board was designed. The board uses Maxim MAX5891 16 bit DACs with a maximum update rate of 600 Msps. Since this module is intended to be used for many different systems throughout the Collider Accelerator complex, it was designed to be as generic as possible. One major application of this DAC card is to implement digital synthesizers to provide drive signals to the various cavities at RHIC. Since RHIC is a storage ring with stores that typically last many hours, extremely low RF noise is a critical requirement. Synchrotron frequencies at RHIC range from a few hertz to several hundred hertz depending on the species and point in the acceleration cycle so close in phase noise is a major concern. The RHIC LLRF system uses the Update Link, a deterministic, high speed data link that broadcasts the revolution frequency and the synchronous phase angle. The digital synthesizers use this data to generate a properly phased analog drive signal. The synthesizers must also provide smooth phase shifts for cogging and support frequency shift rebucketing. One additional feature implemented in the FPGA is a digital waveform generator (WFG) that generates I and Q data pairs based on a user selected amplitude and phase profile as a function of time.« less

Seesaw-like polarized transmission behavior of silver nanowire arrays aligned by off-center spin-coating

NASA Astrophysics Data System (ADS)

Kang, Lu; Chen, Hui; Yang, Zhong-Jian; Yuan, Yongbo; Huang, Han; Yang, Bingchu; Gao, Yongli; Zhou, Conghua

2018-05-01

Straight silver nanowires were synthesized by accelerated oxidization and then aligned into ordered arrays by off-center spin-coating. Seesaw-like behavior was observed in the polarized transmission spectra of the arrays. With the increment of polarization angle (θP, defined as the angle between axis of nanowires and direction of electric field of light), transmission changed repeatedly with a period of 180°, but it moved to opposite directions between the two regions separated by supporting points locating at 494 nm. The behavior is ascribed to the competition between the extinction behaviors of the two modes of surface plasma polaritons on silver nanowires. One is the longitudinal mode which is excited by long wavelengths and tuned by function of cos2( θ p ) and the other is the transverse mode that is excited by short wavelengths and tuned by function of sin2( θ p ). Simulation was performed based on the finite-difference time domain method. The effect of the nanowire diameter and length (aspect ratio) on the position of the supporting point was studied. As nanowire width increased from 20 nm to 350 nm, the supporting point moved from 400 to 500 nm. While it changed slightly when the nanowire length increased from 3 μm to infinitely long (width fixed at 260 nm). In current study, the position of the supporting point is mainly determined by the nanowire width.

H-TiO2/C/MnO2 nanocomposite materials for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Di, Jing; Fu, Xincui; Zheng, Huajun; Jia, Yi

2015-06-01

Functionalized TiO2 nanotube arrays with decoration of MnO2 nanoparticles (denoted as H-TiO2/C/MnO2) have been synthesized in the application of electrochemical capacitors. To improve both areal and gravimetric capacitance, hydrogen treatment and carbon coating process were conducted on TiO2 nanotube arrays. By scanning electron microscopy and X-ray photoelectron spectroscopy, it is confirmed that the nanostructure is formed by the uniform incorporation of MnO2 nanoparticles growing round the surface of the TiO2 nanotube arrays. Impedance analysis proves that the enhanced capacitive is due to the decrease of charge transfer resistance and diffusion resistance. Electrochemical measurements performed on this H-TiO2/C/MnO2 nanocomposite when used as an electrode material for an electrochemical pseudocapacitor presents quasi-rectangular shaped cyclic voltammetry curves up to 100 mV/s, with a large specific capacitance (SC) of 299.8 F g-1 at the current density of 0.5 A g-1 in 1 M Na2SO4 electrolyte. More importantly, the electrode also exhibits long-term cycling stability, only 13 % of SC loss after 2000 continuous charge-discharge cycles. Based on the concept of integrating active materials on highly ordered nanostructure framework, this method can be widely applied to the synthesis of high-performance electrode materials for energy storage.

A facile one-step electrochemical strategy of doping iron, nitrogen, and fluorine into titania nanotube arrays with enhanced visible light photoactivity.

PubMed

Hua, Zulin; Dai, Zhangyan; Bai, Xue; Ye, Zhengfang; Gu, Haixin; Huang, Xin

2015-08-15

Highly ordered iron, nitrogen, and fluorine tri-doped TiO2 (Fe, (N, F)-TiO2) nanotube arrays were successfully synthesized by a facile one-step electrochemical method in an NH4F electrolyte containing Fe ions. The morphology, structure, composition, and photoelectrochemical property of the as-prepared nanotube arrays were characterized by various methods. The photoactivities of the samples were evaluated by the degradation of phenol in an aqueous solution under visible light. Tri-doped TiO2 showed higher photoactivities than undoped TiO2 under visible light. The optimum Fe(3+) doping amount at 0.005M exhibited the highest photoactivity and exceeded that of undoped TiO2 by a factor of 20 times under visible light. The formation of N 2p level near the valence band (VB) contributed to visible light absorption. Doping fluorine and appropriate Fe(3+) ions reduced the photogenerated electrons-holes recombination rate and enhanced visible light photoactivity. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results indicated the presence of synergistic effects in Fe, N, and F tri-doped TiO2, which enhanced visible light photoactivity. The Fe, (N, F)-TiO2 photocatalyst exhibited high stability. Copyright © 2015 Elsevier B.V. All rights reserved.

Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors.

PubMed

Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

2015-10-28

High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (∼1470 F g(-1) at 5 mV s(-1)) and excellent cycling stability with ∼98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg(-1)), a high power density (27.5 kW kg(-1)) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.

Fabrication and investigation of the bionic curved visual microlens array films

NASA Astrophysics Data System (ADS)

Kuo, Wen-Kai; Lin, Syuan-You; Hsu, Sheng-Wei; Yu, Hsin Her

2017-04-01

The compound eyes of insects are smaller, lighter, and have a wider field of view and high sensitivity to moving targets. In recent years, these advantages have attracted many researchers to develop minimized optical devices. In this study, a high performance microlens was fabricated, mimicking the biological visual feature. Polystyrene (PS) microspheres were synthesized by dispersion polymerization first, and then a close-packed monolayer of PS microspheres was assembled by the Langmuir-Blodgett (LB) deposition method. Following this, a 2D polydimethylsiloxane (PDMS) concave mold was fabricated by a soft lithography technique. Different aperture sizes of poly(methyl methacrylate) (PMMA) curved microlens array replicated films were prepared using traditional Chinese medicine cupping tool with a temperature-controllable hot plate, which eliminated the need for inconvenient metal modeling. The optical performance of the curved microlens films were evaluated by a system of optical microscopy (OM) and a home-made image capture charge-coupled device (CCD). The field of view (FOV) and the light intensity distribution of the curved microlens array were also investigated. We found that a broader field of view corresponded to a smaller aperture size of the curved microlens films, as the convex heights of the films are identical. The resolution of the curved microlens films was not affected by their aperture sizes, but was determined by their interommatidial angle and the diameter of the microlens.

Inkjet Printed Surface Enhanced Raman Spectroscopy Array on Cellulose Paper

PubMed Central

Yu, Wei W.; White, Ian M.

2011-01-01

A novel, ultra low-cost surface enhanced Raman spectroscopy (SERS) substrate has been developed by modifying the surface chemistry of cellulose paper and patterning nanoparticle arrays, all with a consumer inkjet printer. Micro/nanofabrication of SERS substrates for on-chip chemical and biomolecular analysis has been under intense investigation. However, the high cost of producing these substrates and the limited shelf life severely limit their use, especially for routine laboratory analysis and for point-of-sample analysis in the field. Paper-based microfluidic biosensing systems have shown great potential as low-cost disposable analysis tools. In this work, this concept is extended to SERS-based detection. Using an inexpensive consumer inkjet printer, cellulose paper substrates are modified to be hydrophobic in the sensing regions. Synthesized silver nanoparticles are printed onto this hydrophobic paper substrate with microscale precision to form sensing arrays. The hydrophobic surface prevents the aqueous sample from spreading throughout the paper and thus concentrates the analyte within the sensing region. A SERS fingerprint signal for Rhodamine 6G dye was observed for samples with as low as 10 femtomoles of analyte in a total sample volume of 1 μL. This extraordinarily simple technique can be used to construct SERS microarrays immediately before sample analysis, enabling ultra low-cost chemical and biomolecular detection in the lab as well as in the field at the point of sample collection. PMID:21058689

MICRONERVA: A Novel Approach to Large Aperture Astronomical Spectroscopy

NASA Astrophysics Data System (ADS)

Hall, Ryan; Plavchan, Peter; Geneser, Claire; Giddens, Frank; Spangler, Sophia

2016-06-01

MICRONERVA (MICRO Novel Exoplanet Radial Velocity Array) is a project to measure precise spectroscopic radial velocities. The cost of telescopes are a strong function of diameter, and light gathering power as opposed to angular resolution is the fundamental driver for telescope design for many spectroscopic science applications. By sacrificing angular resolution, many multiple smaller fiber-fed telescopes can be combined to synthesize the light gathering power of a larger diameter telescope at a lower effective cost. For our MICRONERVA prototype, based upon the larger MINERVA project, we will attempt to demonstrate that an array of four 8-inch CPC Celestron telescopes can be automated with sufficient active guiding precision for robust nightly robotic operations. The light from each telescope is coupled into single mode fibers, which are conveniently matched to the point spread function of 8-inch telescopes, which can be diffraction limited at red wavelengths in typical seeing at good observing sites. Additionally, the output from an array of single mode fibers provides stable output illumination of a spectrograph, which is a critical requirement of future precise radial velocity instrumentation. All of the hardware from the system is automated using Python programs and ASCOM and MaxIm DL software drivers. We will present an overview of the current status of the project and plans for future work. The detection of exoplanets using the techniques of MICRONERVA could potentially enable cost reductions for many types of spectroscopic research.

Smart Construction of Integrated CNTs/Li4Ti5O12 Core/Shell Arrays with Superior High-Rate Performance for Application in Lithium-Ion Batteries.

PubMed

Yao, Zhujun; Xia, Xinhui; Zhou, Cheng-Ao; Zhong, Yu; Wang, Yadong; Deng, Shengjue; Wang, Weiqi; Wang, Xiuli; Tu, Jiangping

2018-03-01

Exploring advanced high-rate anodes is of great importance for the development of next-generation high-power lithium-ion batteries (LIBs). Here, novel carbon nanotubes (CNTs)/Li 4 Ti 5 O 12 (LTO) core/shell arrays on carbon cloth (CC) as integrated high-quality anode are constructed via a facile combined chemical vapor deposition-atomic layer deposition (ALD) method. ALD-synthesized LTO is strongly anchored on the CNTs' skeleton forming core/shell structures with diameters of 70-80 nm the combined advantages including highly conductive network, large surface area, and strong adhesion are obtained in the CC-LTO@CNTs core/shell arrays. The electrochemical performance of the CC-CNTs/LTO electrode is completely studied as the anode of LIBs and it shows noticeable high-rate capability (a capacity of 169 mA h g -1 at 1 C and 112 mA h g -1 at 20 C), as well as a stable cycle life with a capacity retention of 86% after 5000 cycles at 10 C, which is much better than the CC-LTO counterpart. Meanwhile, excellent cycling stability is also demonstrated for the full cell with LiFePO 4 cathode and CC-CNTs/LTO anode (87% capacity retention after 1500 cycles at 10 C). These positive features suggest their promising application in high-power energy storage areas.

CuO-induced signal amplification strategy for multiplexed photoelectrochemical immunosensing using CdS sensitized ZnO nanotubes arrays as photoactive material and AuPd alloy nanoparticles as electron sink.

PubMed

Sun, Guoqiang; Zhang, Yan; Kong, Qingkun; Zheng, Xiaoxiao; Yu, Jinghua; Song, Xianrang

2015-04-15

In this work, multiplexed photoelectrochemical (PEC) immunoassays are introduced into an indium tin oxide (ITO) device. Firstly, the ITO device is fabricated using a simple acid etch treatment method. Secondly, AuPd alloy nanoparticles are electro-deposited on ITO working electrodes as electron sink to construct the immunosensor platform. After that, ZnO nanotubes (ZNTs) arrays are synthesized via chemical etching of ZnO nanorods that are grown on AuPd surface by electrochemical deposition method. Subsequently, CdS is electro-deposited on ZNTs arrays and used as photoactive material. Then, CuO nanoseeds are labeled with signal antibodies and firstly used as PEC signal amplification label. The introduction of CuO brings signal amplification because of the conduction band (CB) of both CuO and ZnO are lower than that of CdS, CuO will compete the photo-induced electrons in CB of CdS with ZnO, leading to the decrease of the photocurrent intensity. Using cancer antigen 125, prostate specific antigen and α-fetoprotein as model analytes, the proposed immunoassay exhibits excellent precision and sensitivity. Meanwhile, this work provides a promising, addressable and simple strategy for the multi-detection of tumor markers. Copyright © 2014 Elsevier B.V. All rights reserved.

High index glass thin film processing for photonics and photovoltaic (PV) applications

NASA Astrophysics Data System (ADS)

Ogbuu, Okechukwu Anthony

To favorably compete with fossil-fuel technology, the greatest challenge for thin film solar-cells is to improve efficiency and reduce material cost. Thickness scaling to thin film reduces material cost but affects the light absorption in the cells; therefore a concept that traps incident photons and increases its optical path length is needed to boost absorption in thin film solar cells. One approach is the integration of low symmetric gratings (LSG), using high index material, on either the front-side or backside of 30 um thin c-Si cells. In this study, Multicomponent TeO2--Bi2O 3--ZnO (TBZ) glass thin films were prepared using RF magnetron sputtering under different oxygen flow rates. The influences of oxygen flow rate on the structural and optical properties of the resulting thin films were investigated. The structural origin of the optical property variation was studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman Spectroscopy, and transmission electron microscopy. The results indicate that TBZ glass thin film is a suitable material for front side LSG material photovoltaic and photonics applications due to their amorphous nature, high refractive index (n > 2), broad band optical transparency window, low processing temperature. We developed a simple maskless method to pattern sputtered tellurite based glass thin films using unconventional agarose hydrogel mediated wet etching. Conventional wet etching process, while claiming low cost and high throughput, suffers from reproducibility and pattern fidelity issues due to the isotropic nature of wet chemical etching when applied to glasses and polymers. This method overcomes these challenges by using an agarose hydrogel stamp to mediate a conformal etching process. In our maskless method, agarose hydrogel stamps are patterned following a standard soft lithography and replica molding process from micropatterned masters and soaked in a chemical etchant. The micro-scale features on the stamp are subsequently transferred into glass and polymer thin films via conformal wet etching. High refractive index chalcogenide glass (n = 2.6) thin films with composition As20Se80 was selected for backside LSG material due to their attractive properties. We developed an optimized integration protocol for LSG integration and successfully integrated these LSG structures at the back side of both 30 microm c-Si solar cells and standalone 30 microm c-Si wafers. Optical and electrical characterization of LSG on thin c-Si cells shows that LSG structures create higher absorption enhancement and external quantum efficiency at long wavelengths.

Antimicrobial activity and physical characterization of silver nanoparticles green synthesized using nitrate reductase from Fusarium oxysporum.

PubMed

Gholami-Shabani, Mohammadhassan; Akbarzadeh, Azim; Norouzian, Dariush; Amini, Abdolhossein; Gholami-Shabani, Zeynab; Imani, Afshin; Chiani, Mohsen; Riazi, Gholamhossein; Shams-Ghahfarokhi, Masoomeh; Razzaghi-Abyaneh, Mehdi

2014-04-01

Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of -34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine.

Optimization of Microphone Locations for Acoustic Liner Impedance Eduction

NASA Technical Reports Server (NTRS)

Jones, M. G.; Watson, W. R.; June, J. C.

2015-01-01

Two impedance eduction methods are explored for use with data acquired in the NASA Langley Grazing Flow Impedance Tube. The first is an indirect method based on the convected Helmholtz equation, and the second is a direct method based on the Kumaresan and Tufts algorithm. Synthesized no-flow data, with random jitter to represent measurement error, are used to evaluate a number of possible microphone locations. Statistical approaches are used to evaluate the suitability of each set of microphone locations. Given the computational resources required, small sample statistics are employed for the indirect method. Since the direct method is much less computationally intensive, a Monte Carlo approach is employed to gather its statistics. A comparison of results achieved with full and reduced sets of microphone locations is used to determine which sets of microphone locations are acceptable. For the indirect method, each array that includes microphones in all three regions (upstream and downstream hard wall sections, and liner test section) provides acceptable results, even when as few as eight microphones are employed. The best arrays employ microphones well away from the leading and trailing edges of the liner. The direct method is constrained to use microphones opposite the liner. Although a number of arrays are acceptable, the optimum set employs 14 microphones positioned well away from the leading and trailing edges of the liner. The selected sets of microphone locations are also evaluated with data measured for ceramic tubular and perforate-over-honeycomb liners at three flow conditions (Mach 0.0, 0.3, and 0.5). They compare favorably with results attained using all 53 microphone locations. Although different optimum microphone locations are selected for the two impedance eduction methods, there is significant overlap. Thus, the union of these two microphone arrays is preferred, as it supports usage of both methods. This array contains 3 microphones in the upstream hard wall section, 14 microphones opposite the liner, and 3 microphones in the downstream hard wall section.

Free-standing 3D graphene/polyaniline composite film electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Wang, Shiyong; Ma, Li; Gan, Mengyu; Fu, Shenna; Dai, Wenqin; Zhou, Tao; Sun, Xiaowu; Wang, Huihui; Wang, Huining

2015-12-01

The research paper describes polyaniline (PANI) nanowires array on flexible polystyrene microsphere/reduced graphene (PS/rGN) film is synthesized by dilute polymerization, and then the PS microspheres are removed to form free-standing three-dimensional (3D) rGN/PANI composite film. The chemical and structural properties of the 3D rGN/PANI film are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET), and the results confirm the 3D rGN/PANI film is synthesized successfully. When the film is used as a supercapacitor electrode, the maximum specific capacitance is as high as 740 F g-1 (or 581 F cm-3 for volumetric capacitance) at a current density of 0.5 A g-1 and the specific capacitance retains 87% of the initial after constant charge-discharge 1000 cycles at current density of 10 A g-1. It is believed that the free-standing 3D rGN/PANI film will have a great potential for application in supercapacitors.

Thickness limitations in carbon nanotube reinforced silicon nitride coatings synthesized by vapor infiltration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eres, Gyula

Chemical vapor infiltration is a convenient method for synthesizing carbon nanotube (CNT)-reinforced ceramic coatings. The thickness over which infiltration is relatively uniform is limited by gas phase diffusion in the pore structure. These effects were investigated in two types of silicon nitride matrix composites. With CNTs that were distributed uniformly on the substrate surface dense coatings were limited to thicknesses of several microns. With dual structured CNT arrays produced by photolithography coatings up to 400 gm thick were obtained with minimal residual porosity. Gas transport into these dual structured materials was facilitated by creating micron sized channels between "CNT pillars"more » (i.e. each pillar consisted of a large number of individual CNTs). The experimental results are consistent with basic comparisons between the rates of gas diffusion and silicon nitride growth in porous structures. This analysis also provides a general insight into optimizing infiltration conditions during the fabrication of thick CNT-reinforced composite coatings. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.« less

Disintegration of Nascent Replication Bubbles during Thymine Starvation Triggers RecA- and RecBCD-dependent Replication Origin Destruction*

PubMed Central

Kuong, Kawai J.; Kuzminov, Andrei

2012-01-01

Thymineless death strikes cells unable to synthesize DNA precursor dTTP, with the nature of chromosomal damage still unclear. Thymine starvation stalls replication forks, whereas accumulating evidence indicates the replication origin is also affected. Using a novel DNA labeling technique, here we show that replication slowly continues in thymine-starved cells, but the newly synthesized DNA becomes fragmented and degraded. This degradation apparently releases enough thymine to sustain initiation of new replication bubbles from the chromosomal origin, which destabilizes the origin in a RecA-dependent manner. Marker frequency analysis with gene arrays 1) reveals destruction of the origin-centered chromosomal segment in RecA+ cells; 2) confirms origin accumulation in the recA mutants; and 3) identifies the sites around the origin where destruction initiates in the recBCD mutants. We propose that thymineless cells convert persistent single-strand gaps behind replication forks into double-strand breaks, using the released thymine for new initiations, whereas subsequent disintegration of small replication bubbles causes replication origin destruction. PMID:22621921

Synthesis and surface activity properties of alkylphenol polyoxyethylene nonionic trimeric surfactants

NASA Astrophysics Data System (ADS)

Yang, Fang; Li, Gang; Qi, Jian; Zhang, Song-Mei; Liu, Rong

2010-10-01

A series of trimeric n-alkylphenol polyoxyethylene surfactants (TAP) were successfully synthesized and the molecular structure were confirmed by NMR, FTIR spectrum and elemental analysis. Using the same synthesis route, the trimeric nonylphenol polyoxyethylene surfactant (TNP) was synthesized using industrial product nonylphenol and paraformaldehyde, and its molecular structure was characterized by 1HNMR, FTIR spectrum and elemental analysis. The optimal reaction conditions were established. The surface activity properties of TAP and TNP (such as the critical micelle concentration (cmc), the values of surface tension at the cmc ( γcmc), the maximum surface excess concentration ( Γcmc), and the minimum surface area per surfactant molecule ( Acmc)), were determined by means of Wilhelmy plate method and steady-state fluorescence probe method, respectively. The experimental results show that the lengths of the hydrophilic group oxyethylene (EO) chains and hydrophobic group methylene chains have an influence on the cmc, γcmc, Γcmc, and Acmc of series of surfactants. Furthermore, TAP are arranged to staggered three-dimensional array mode at the air-water interface, which has exhibited better surface properties, such as low cmc values, strong adsorption affinities and wet abilities.

a Search for Interstellar Urea with Carma

NASA Astrophysics Data System (ADS)

Kuo, H.-L.; Snyder, L. E.; Friedel, D. N.; Looney, L. W.; McCall, B. J.; Remijan, A. J.; Lovas, F. J.; Hollis, J. M.

2009-06-01

Urea, a molecule discovered in human urine by H. M Rouelle in 1773, also plays a significant role in prebiotic chemistry. Previous BIMA observations have suggested that interstellar urea [(NH_2)_2CO] is a compact hot core molecule such as the other large molecules methyl formate and acetic acid (2008, 63rd OSU Symposium On Molecular Spectroscopy, RF11). We have conducted an extensive search for urea toward the high mass hot molecular core Sgr B2(N-LMH) using the CARMA array. The resolution at 1 mm enables favorable coupling of source size and synthesized beam size, which was found to be essential for flux measurements and detection limits of weak signals. The 2.5^''×2^'' synthesized beam of CARMA significantly resolves out the extended emission and reveals the weak lines that were previously blended with nearby transitions. Our analysis indicates that these lines are likely to be urea since they are now less contaminated, the resulting observed line frequencies are coincident with a set of overlapping connecting urea lines, and the observed line intensities are consistent with expected line strengths of urea.

Peptide arrays on cellulose support: SPOT synthesis, a time and cost efficient method for synthesis of large numbers of peptides in a parallel and addressable fashion.

PubMed

Hilpert, Kai; Winkler, Dirk F H; Hancock, Robert E W

2007-01-01

Peptide synthesis on cellulose using SPOT technology allows the parallel synthesis of large numbers of addressable peptides in small amounts. In addition, the cost per peptide is less than 1% of peptides synthesized conventionally on resin. The SPOT method follows standard fluorenyl-methoxy-carbonyl chemistry on conventional cellulose sheets, and can utilize more than 600 different building blocks. The procedure involves three phases: preparation of the cellulose membrane, stepwise coupling of the amino acids and cleavage of the side-chain protection groups. If necessary, peptides can be cleaved from the membrane for assays performed using soluble peptides. These features make this method an excellent tool for screening large numbers of peptides for many different purposes. Potential applications range from simple binding assays, to more sophisticated enzyme assays and studies with living microbes or cells. The time required to complete the protocol depends on the number and length of the peptides. For example, 400 9-mer peptides can be synthesized within 6 days.

High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, J. C.; Department of Engineering Physics, Polytechnique Montréal, Montreal, Quebec H3A 3A7; Jha, S. K., E-mail: skylec@gmail.com, E-mail: apwjzh@cityu.edu.hk

2014-11-10

Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B{sub 4}C target in an Ar/N{sub 2} gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

Hardware Prototyping of Neural Network based Fetal Electrocardiogram Extraction

NASA Astrophysics Data System (ADS)

Hasan, M. A.; Reaz, M. B. I.

2012-01-01

The aim of this paper is to model the algorithm for Fetal ECG (FECG) extraction from composite abdominal ECG (AECG) using VHDL (Very High Speed Integrated Circuit Hardware Description Language) for FPGA (Field Programmable Gate Array) implementation. Artificial Neural Network that provides efficient and effective ways of separating FECG signal from composite AECG signal has been designed. The proposed method gives an accuracy of 93.7% for R-peak detection in FHR monitoring. The designed VHDL model is synthesized and fitted into Altera's Stratix II EP2S15F484C3 using the Quartus II version 8.0 Web Edition for FPGA implementation.

Methods of nanoassembly of a fractal polymer and materials formed thereby

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newkome, George R; Moorefield, Charles N

2012-07-24

The invention relates to the formation of synthesized fractal constructs and the methods of chemical self-assembly for the preparation of a non-dendritic, nano-scale, fractal constructs or molecules. More particularly, the invention relates to fractal constructs formed by molecular self-assembly, to create synthetic, nanometer-scale fractal shapes. In an embodiment, a nanoscale Sierpinski hexagonal gasket is formed. This non-dendritic, perfectly self-similar fractal macromolecule is comprised of bisterpyridine building blocks that are bound together by coordination to 36 Ru and 6 Fe ions to form a nearly planar array of increasingly larger hexagons around a hollow center.

Methods of nanoassembly of a fractal polymer and materials formed thereby

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newkome, George R; Moorefield, Charles N

2014-09-23

The invention relates to the formation of synthesized fractal constructs and the methods of chemical self-assembly for the preparation of a non-dendritic, nano-scale, fractal constructs or molecules. More particularly, the invention relates to fractal constructs formed by molecular self-assembly, to create synthetic, nanometer-scale fractal shapes. In an embodiment, a nanoscale Sierpinski hexagonal gasket is formed. This non-dendritic, perfectly self-similar fractal macromolecule is comprised of bisterpyridine building blocks that are bound together by coordination to (36) Ru and (6) Fe ions to form a nearly planar array of increasingly larger hexagons around a hollow center.

Catechin prodrugs and analogs: a new array of chemical entities with improved pharmacological and pharmacokinetic properties.

PubMed

Bansal, Sumit; Vyas, Sandeep; Bhattacharya, Shoumyo; Sharma, Manu

2013-10-11

Extensive research on tea catechins, mainly (-)-epigallocatechin gallate, has shown numerous health promoting effects. However, various clinical studies demonstrated several issues associated with tea catechins which account for their poor systemic bioavailability. In order to improve pharmacological activity and bioavailability of natural tea catechins, two major strategies have been adopted to date which include synthesizing catechin analogs/prodrugs and the development of novel drug delivery systems. In this review, we provide a detailed account of novel synthetic analogs/prodrugs as well as novel drug delivery approaches used for natural tea catechins to make them therapeutically potent drug-like molecules.

Micromagnetic simulation study of a disordered model for one-dimensional granular perovskite manganite oxide nanostructures

NASA Astrophysics Data System (ADS)

Longone, P.; Romá, F.

2018-06-01

Chemical techniques are an efficient method to synthesize one-dimensional perovskite manganite oxide nanostructures with a granular morphology, that is, formed by arrays of monodomain magnetic nanoparticles. Integrating the stochastic Landau-Lifshitz-Gilbert equation, we simulate the dynamics of a simple disordered model for such materials that only takes into account the morphological characteristics of their nanograins. We show that it is possible to describe reasonably well experimental hysteresis loops reported in the literature for single La0.67Ca0.33MnO3 nanotubes and powders of these nanostructures, simulating small systems consisting of only 100 nanoparticles.

Multispectral high-resolution hologram generation using orthographic projection images

NASA Astrophysics Data System (ADS)

Muniraj, I.; Guo, C.; Sheridan, J. T.

2016-08-01

We present a new method of synthesizing a digital hologram of three-dimensional (3D) real-world objects from multiple orthographic projection images (OPI). A high-resolution multiple perspectives of 3D objects (i.e., two dimensional elemental image array) are captured under incoherent white light using synthetic aperture integral imaging (SAII) technique and their OPIs are obtained respectively. The reference beam is then multiplied with the corresponding OPI and integrated to form a Fourier hologram. Eventually, a modified phase retrieval algorithm (GS/HIO) is applied to reconstruct the hologram. The principle is validated experimentally and the results support the feasibility of the proposed method.

Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array

PubMed Central

Xie, Yangbo; Shen, Chen; Wang, Wenqi; Li, Junfei; Suo, Dingjie; Popa, Bogdan-Ioan; Jing, Yun; Cummer, Steven A.

2016-01-01

Acoustic holographic rendering in complete analogy with optical holography are useful for various applications, ranging from multi-focal lensing, multiplexed sensing and synthesizing three-dimensional complex sound fields. Conventional approaches rely on a large number of active transducers and phase shifting circuits. In this paper we show that by using passive metamaterials as subwavelength pixels, holographic rendering can be achieved without cumbersome circuitry and with only a single transducer, thus significantly reducing system complexity. Such metamaterial-based holograms can serve as versatile platforms for various advanced acoustic wave manipulation and signal modulation, leading to new possibilities in acoustic sensing, energy deposition and medical diagnostic imaging. PMID:27739472

Synthesis and Characterization of Manganese Sponge doped with TiO2

NASA Astrophysics Data System (ADS)

Mallikarjun, patil

2017-06-01

The aviation and mechanical industry has seen tremendous growth in recent years. While these trends only continue, the materials on development of better fabrication technologies. Spongy materials are projected as favourable materials for the future as porous in nature. The current paper devotes to enhance mechanical properties by the use of Manganese sponge doped with TiO2 possess an outstanding array of properties not readily achievable with other materials. Samples were synthesized by Kroll process and solid-state reaction. The specified materials compares well with the presently used aeromechanical materials in all terms. The scope for further research work in this area will be outlined.

Enhanced Structural and Luminescent Properties of Carbon-Assisted ZnO Nanorod Arrays on (100) Si Substrate

NASA Astrophysics Data System (ADS)

Yoon, Im Taek; Cho, Hak Dong; Lee, Sejoon; Roshchupkin, Dmitry V.

2018-02-01

We have fabricated as-grown ZnO nanorods (NRs) and carbon-assisted NR arrays on semi-insulating (100)-oriented Si substrates. We compared the structural and luminescent properties of them. High-resolution transmission microscopy, field emission scanning electron microscopy, x-ray diffraction and energy-dispersive x-ray revealed that the as-grown ZnO NRs and carbon-assisted ZnO NRs were single crystals with a hexagonal wurtzite structure, and grew with a c-axis orientation perpendicular to the Si substrate. These measurements show that the carbon-assisted ZnO NRs were better synthesized vertically on an Si substrate compared to the as-grown ZnO NRs. Photoluminescence measurements showed that luminescence intensity of the carbon-assisted ZnO NRs was enhanced compared to the as-grown ZnO NRs. The enhanced luminescence intensity of the carbon-assisted ZnO demonstrates the possible improvement in the performance of photovoltaic nanodevices based on ZnO-like materials. This method can be applied to the fabrication of well-aligned ZnO NRs used widely in optoelectronic devices.

Stereo matching and view interpolation based on image domain triangulation.

PubMed

Fickel, Guilherme Pinto; Jung, Claudio R; Malzbender, Tom; Samadani, Ramin; Culbertson, Bruce

2013-09-01

This paper presents a new approach for stereo matching and view interpolation problems based on triangular tessellations suitable for a linear array of rectified cameras. The domain of the reference image is initially partitioned into triangular regions using edge and scale information, aiming to place vertices along image edges and increase the number of triangles in textured regions. A region-based matching algorithm is then used to find an initial disparity for each triangle, and a refinement stage is applied to change the disparity at the vertices of the triangles, generating a piecewise linear disparity map. A simple post-processing procedure is applied to connect triangles with similar disparities generating a full 3D mesh related to each camera (view), which are used to generate new synthesized views along the linear camera array. With the proposed framework, view interpolation reduces to the trivial task of rendering polygonal meshes, which can be done very fast, particularly when GPUs are employed. Furthermore, the generated views are hole-free, unlike most point-based view interpolation schemes that require some kind of post-processing procedures to fill holes.

TiO2 Nanotube Arrays: Fabricated by Soft-Hard Template and the Grain Size Dependence of Field Emission Performance

NASA Astrophysics Data System (ADS)

Yang, Xuxin; Ma, Pei; Qi, Hui; Zhao, Jingxin; Wu, Qiang; You, Jichun; Li, Yongjin

2017-11-01

Highly ordered TiO2 nanotube (TNT) arrays were successfully synthesized by the combination of soft and hard templates. In the fabrication of them, anodic aluminum oxide membranes act as the hard template while the self-assembly of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) complexed with titanium-tetraisopropoxide (TTIP, the precursor of TiO2) provides the soft template to control the grain size of TiO2 nanotubes. Our results indicate that the field emission (FE) performance depends crucially on the grain size of the calcinated TiO2 which is dominated by the PS-b-PEO and its blending ratio with TTIP. The optimized sample (with the TTIP/PEO ratio of 3.87) exhibits excellent FE performances involving both a low turn-on field of 3.3 V/um and a high current density of 7.6 mA/cm2 at 12.7 V/μm. The enhanced FE properties can be attributed to the low effective work function (1.2 eV) resulted from the smaller grain size of TiO2.